FI123194B - Reactor water level measurement system and reactor water level measurement method - Google Patents

Description

Reactor water level measurement system and reactor water level measurement method

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a technique for measuring the level of a liquid in a container.

Description of the Related Art

Many nuclear power plants use a light water reactor, such as a boiling water reactor and a pressurized water reactor. Referring to Figure 26, an exemplary boiling water reactor configuration is described.

The Boiling Water Reactor 200 has a solid reactor pressure vessel 201 containing high temperature and high pressure water (for example, an internal pressure of 72.1 kg / cm 2 * g and a temperature of 287 ° C).

The reactor pressure vessel 201 includes a reactor core 202 which is a source of fission energy generated by a plurality of uranium, plutonium, or similar fuel assemblies, a housing 203 enclosing and supporting the reactor core 202, an internal pump 205 forcibly circulating the reactor to recover water a water separator 206 which removes water from the water vapor obtained from the reactor water by a centrifuge function, a steam dryer 207 mounted on a steam water separator 206 also to remove water from the steam produced by the steam water separator 20 206 to adjust the control rod 208.

The high temperature and high pressure dry steam, from which the water depleting the turbine efficiency has been removed by the steam dryer 207, is removed from the reactor pressure vessel 201 via the main steam pipe 210 and fed to the steam turbine (not pre-set).

Outside the reactor pressure vessel 201, a biological shield i ^ 211 is mounted to prevent radiation leakage from the reactor core 202, such as neutron radiation and x gamma rays, reducing the radiation dose in the immediate area. Reactor pressure vessel 201

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The thermal insulation 212 is arranged to surround the entire side of the reactor pressure vessel o.

In normal operation, the core of the reactor pressure vessel 201 is divided into two parts at the top of the reactor core 202 or at the middle of the steam / water separator. The part below the level is the water part of the reactor filled with the reactor water, and the part above the level is the steam part filled with steam from the reactor water. The water level L (reactor water level) of reactor pressure vessel 201 is significant for power control and reactor safety. To detect the deviation of the water level L, a reactor water level measurement system 5 is installed which continuously monitors the reactor water level.

For the boiling water reactor, a differential water level meter (see, for example, Patent Document 1 (Japanese Patent Publication No. 5-302840)) is usually used to measure the reactor pressure vessel water level. The Differential Water Level Gauge has been proven to be very safe and reliable. 10 Reactor water level is a very important parameter for reactor control and safety. Accordingly, several types of reactor water level measurement systems based on different principles are preferably used together to improve measurement reliability. The following are examples of common water level measurement techniques.

15 (1) The container containing the liquid has a water level measuring tube installed outside it. The water level measuring tube has a Driving portion communicating with the gas phase region of the vessel and a Driving portion communicating with the liquid phase region of the vessel. Ultrasonic waves are transmitted from the liquid phase to the gas phase in a water level measuring tube, and the water level in the vessel is measured from the propagation times of the reflected gas and other reflected ultrasonic particles at the gas-liquid interface (see Patent Document 2 (Japanese Patent No. 3-289520)).

(2) The system for checking vehicle diesel engine lubricating oil or the like comprises a floating oil float, a demarcation unit that limits the horizontal deviation of the float, and a position detection unit that detects the vertical position of the float. The system detects the amount of lubricating oil at the position of the float (see Patent Document 3 (Japanese Published Pa-5 Examination No. 2005-308563)).

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(3) The reduction in reflection at the reflection point of the inner surface of the liquid tank of the ultrasonic waves determines whether the reflection point 00 30 is in the gas phase or the liquid phase (see Patent Document 4 (Japanese Patent Publication No. 11-218436)).

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Summary of the Invention Water Level Measurement Techniques described in Patent Documents 2 and 3 improve the accuracy of water level measurement by preparing an object in the liquid phase region of the water level tube and calculating the density of the liquid phase from the propagation time of the ultrasound waves. As a result, the structure in the water level measuring tube is complicated.

The present invention has been invented from a circumferential point of view, and the first object of the present invention is to provide a reactor water level measurement system and a reactor water level measurement method that can accurately measure the reactor water level without the need for an ultrasonic reflector in a water level measuring tube.

Furthermore, in connection with the technique described in Patent Document 4, the reflectance of the ultrasonic wave from the reflection point on the inner or outer surface of the liquid tank is greatly influenced by the surface factors on the inner or outer surface. Thus, the measurement of the water level is affected by environmental changes that cause changes in surface factors, aging or displacement of the reflection point.

Thus, another object of the present invention is to provide a fluid level measuring system that maintains good reliability even if the system is significantly affected by environmental changes, aging, or shifting of the reflection point causing changes in surface factors.

Of course, a water level measuring system other than a differential pressure type must maintain good measurement accuracy for a long period of time. In addition, the water level measurement system preferably has a simple configuration in terms of cost and ease of maintenance.

Reactor water level measurement techniques described in Patent Document 1 and the like are based on the concept of a water level measuring tube communicating with the reactor pressure vessel core at at least two locations at different levels and containing reactor water and steam taken from the reactor pressure vessel and measuring the water level in the water level measuring tube. The reactor water taken from the reactor pressure vessel into the water level measuring tube differs in temperature and pressure from the reactor water in the reactor pressure vessel, and thus the water level measuring tubes

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The water level in the vessel cannot be directly considered as the water level in the reactor pressure vessel.

T Thus, accurate estimation of the water level in the reactor pressure vessel from the water level in the water level measuring tube requires various corrections and complexities. These techniques make the process and system used complicated.

Thus, a third object of the present invention is to provide a reactor water level measurement system of a different type from a differential pressure type which can measure the water level of the reactor in a precisely simplified configuration.

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To achieve the first object, the water level measuring system of the present invention is a reactor water level measuring system that measures the reactor pressure vessel water level, comprising: a water level measuring tube mounted outside the reactor pressure vessel and having a puller portion communicating with a saturated vapor phase region a Driving portion communicating with the aqueous phase region of a reactor in a pressure vessel; gas phase side of the detection unit, which transmits an ultrasonic wave or the microwave from the gas phase to the liquid phase water level Measuring Stick-pipe with receiving reflection waves the gas-liquid interface and produces a 10-refl tusaaltosignaalin; The liquid phase side of the detection unit, which transmits an ultrasonic wave from the liquid phase to the gas phase the water level in the measuring tube, receives reflection waves the gas-liquid interface and produce heijastusaaltosignaalin; and water-level calculation unit that calculates the water level in the reactor using a gas-phase produced heijastusaaltosignaalia side detection unit and the liquid phase side heijastusaaltosignaalia produced ilmaisuyk-15 coker.

Further, the reactor water level measuring method of the present invention is a reactor water level measuring method that measures the level of water in a reactor pressure vessel, comprising: providing a water level measuring tube outside the reactor pressure vessel having a pull portion communicating with a saturated vapor phase region in the reactor pressure vessel; a pulling portion communicating with the reactor water vessel region in the reactor pressure vessel; Vapor-side detection step of transmitting the ultrasonic wave from the gas phase into the liquid phase the water level in the measuring tube, receiving refl-tusaalto gas-liquid interface and generating heijastusaaltosignaali; a liquid-side detection step 25 of transmitting the ultrasonic wave from the liquid phase to the gas phase the water level in the measuring tube, receiving a reflection wave of gas-liquid boundary surface, and five-produced heijastusaaltosignaali; and calculating the reactor water level

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They ^ which uses the produced gas phase side of the detecting step in heijastusaaltosig- margin and heijastusaaltosignaalia produced in a liquid phase side of the detecting step.

In order to achieve another object, according to the present invention the measuring system is a liquid level measuring system comprising: an ultrasonic transmitter unit mounted on the outer surface of a tube and transmitting and receiving an ultrasonic wave; a control unit which transmits an instruction signal to the ultrasonic transceiver unit for transmitting the ultrasonic wave into the tube; a receiver unit receiving an ultrasound wave receiving signal from the ultrasonic transceiver unit; and a calculating unit which determines, based on the reception signal received by the receiver unit, whether the ultrasonic wave received by the ultrasonic transceiver unit includes a reflection wave from a portion of the inner surface of the tube facing the ultrasonic transceiver unit.

Further, the liquid level measuring system of the present invention is a liquid level measuring system comprising: an ultrasonic transceiver unit mounted on the outer surface of a tube and transmitting and receiving an ultrasonic wave; a second ultrasonic transceiver unit mounted on the outer surface of the tube at a position opposite the ultrasonic transceiver unit; A control unit which transmits to the ultrasonic transceiver unit a command signal for transmitting the ultrasonic wave to the tube; a receiver unit receiving an ultrasound wave receiving signal from another ultrasonic transceiver unit; and a calculating unit which determines, based on the ultrasonic wave receiving signal received by the receiver unit, whether the ultrasonic wave received by the second ultrasonic transceiver receiving unit includes a transmitted wave transmitted by the ultrasonic transceiver unit and transmitted through a tube.

Further, the liquid level measuring system of the present invention is a liquid level measuring system comprising: a first ultrasonic transceiver unit mounted on the outer surface of a tube and transmitting and receiving an ultrasonic wave; a second ultrasonic transceiver unit mounted on the outer surface of the tube at a position opposite the first ultrasonic transceiver unit; a third ultrasonic transceiver unit mounted on the outer surface of the tube at a position displaced from the position of the first ultrasonic transceiver unit in the direction of the tube axis; a fourth ultrasonic transceiver unit mounted on the outer surface of the tube at a position opposite the third ultrasonic transceiver unit; a control unit transmitting to each of the first ultrasonic transceiver units, the second ultrasound transceiver unit;

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an audio transceiver unit, a third ultrasonic transceiver unit v, and a fourth ultrasonic transceiver unit for transmitting a command signal ultrasound wave 00 30 to a tube; a receiver unit receiving the ultrasonic wave receiving a signal from each of the first ultrasonic transceiver units, the second ultrasonic transceiver unit, the third ultrasonic transceiver unit and the fourth ultrasonic transceiver unit; and a calculating unit calculating for each of the first ultrasound transceiver units, the second ultrasound transceiver unit, the third ultrasound transceiver unit and the fourth ultrasound transceiver unit, based on an ultrasonic sound receiving signal, and a transmitted wave coming from an ultrasound transceiver unit mounted on the outer surface of the tube at an opposite location displaced in the direction of the tube axis.

To achieve the third purpose of the water level of the reactor measurement system that measures the water level in the reactor pressure vessel of the reactor, comprising: a water level in the measurement pipe, which is embedded in the pressure vessel of the reactor to the surrounding heat insulation, which communicates with the reactor pressure vessel, the interior of the with-one ection at least two locations at different levels, and includes a reactor pressure vessel water and steam taken up by the reactor; an ultrasonic transceiver unit, which transmits an ultrasonic wave to the water surface in the water level measuring tube, receives a reflection wave from the water surface and outputs a reflection wave signal; and a water level calculating unit which calculates the level of water in the water measuring tube as the intracellular water level using the reflection time between the ultrasound transmitting and the reflection wave and the acoustic velocity of the ultrasonic wave using the reflection wave signal produced by the ultrasonic transceiver unit water level.

A first advantage of the present invention is that the water level of the reactor can be measured very accurately without the use of an ultrasonic reflector in the water level measuring tube.

Another advantage of the present invention is that the location of the relevant point in the gas phase or liquid phase is determined by the presence or absence of a reflection wave or the like in the water level measuring tube so that water level measurement is less affected by surface factor changes.

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A third advantage of the present invention is that the water level in the water level measuring tube is kept close to the water level in the reactor pressure vessel, and the water level in the reactor pressure vessel can be very accurately measured by a simple system | configuration.

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g Description of the drawings

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? Fig. 1 is a diagram illustrating a reactor water level measurement system according to the first embodiment of the present invention; Figure 2 is a diagram (in perspective) of a float of the water level measurement system of the reactor of the first embodiment; Fig. 3 is a diagram illustrating a reactor water level measurement system according to a second embodiment of the invention; Fig. 4 is a diagram (in perspective) of the water level measuring tube of the reactor water level measurement system of the second embodiment; Figure 5 is a graph showing the signal strength of a microwave before and after reflection from a gas-liquid interface; Fig. 6 is a diagram illustrating a reactor water level measurement system according to a third embodiment of the invention; Fig. 7 is a diagram (in perspective) of a magnetized float of a reactor water level measuring system according to a third embodiment; Fig. 8 is a diagram (longitudinal cross-section) of a float position reader of a reactor water level measuring system according to a third embodiment; Fig. 9 is a schematic longitudinal cross-sectional view of a water level measuring tube with a fluid level measuring system according to the fourth embodiment attached; Fig. 10 is an enlarged partial longitudinal cross-sectional view of a water level measuring tube with a fluid level measuring system according to the fourth embodiment attached thereto; Fig. 11 shows enlarged partial longitudinal cross-sectional views of a water level measuring tube to illustrate the operation of a liquid level measuring system according to a fourth embodiment; Fig. 12 (a) is a graph showing a reception signal when the reflection point is in the gas phase; Fig. 12 (b) is a graph showing a receive signal when the reflection point is in the liquid phase; Fig. 13 shows enlarged partial longitudinal views of the water level measuring tube

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^ cross-sectional views to illustrate the operation of the fluid level measuring system of the fourth embodiment; FIG. 14 includes enlarged partial longitudinal sections of the water level measuring tube full cross-sectional views to illustrate the operation of the fluid level measuring system of the fourth embodiment; Fig. 15 is an enlarged partial longitudinal cross-sectional view of the water from a level measuring tube fitted with a 00 35 liquid level measuring system according to a fifth embodiment; Fig. 16 (a) is a front view of the reflector 24; Figure 16 (b) is a cross-sectional view taken along line A-A of Figure 16 (a); Fig. 17 is a partial longitudinal cross-sectional view of a water level measuring tube with a fluid level measuring system according to a sixth embodiment; Fig. 18 is a partial longitudinal cross-sectional view of a water level measuring tube with a fluid level measuring system according to a seventh embodiment; Fig. 19 is a diagram illustrating a reactor water level measurement system according to an eighth embodiment of the invention; Figure 20 is a graph showing a pattern matching in the water level calculation process performed by the water level calculation unit shown in Figure 2; Figure 21 is a graph showing a pattern matching in the water level calculation process performed by the water level calculation unit shown in Figure 2; Fig. 22 is a diagram illustrating a reactor water level measurement system according to a ninth embodiment of the invention; Fig. 23 is a diagram showing a water level measurement system for a reactor according to a tenth embodiment of the invention; Figure 24 is a diagram illustrating a reactor water level measurement system according to an eleventh embodiment of the invention; Fig. 25 is a diagram showing a water level measurement system for a reactor according to a twelfth embodiment of the invention; and Fig. 26 is a diagram showing a boiling water reactor for which the reactor water level measurement system of the present invention is used.

Detailed Description of Preferred Embodiments

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Referring to the figures, embodiments of the present invention are described with reference to boiling water reactor applications.

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^ (First Embodiment) g Fig. 1 is a diagram illustrating a first embodiment of the present invention

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30 according to the embodiment of the present invention. boiling

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§ a pressure vessel 21 is installed in the reactor tank (not shown) in the water reactor.

The reactor core shell 24 forming the reactor core is mounted in the reactor pressure vessel 21, and the reactor core shell 21 in the reactor pressure vessel 21 is submerged in cooling water 25.

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An angled U-shaped water level measuring tube 26 is mounted in an upright position on the outer side wall of the reactor pressure vessel 21. The water level measuring tube 26 serves as a reference arm. The water level measuring tube 26 passes through the outer wall of the reactor pressure vessel and thus communicates with its interior, and the cooling water 25 in the pressure vessel 21 of the reactor 5 is introduced into the water level measuring tube 26.

As shown in Figure 1, the water level of the reactor measurement system 20 is a gas phase side of the detection unit (40a, 43a, 41), a liquid phase side of the detection unit (20b, 43b, 41), the float 58, the water level calculation unit 31 and neck-co-driver (32, 33).

As shown in Fig. 1, the water level measuring tube 26 has a conductive portion 26a communicating with a saturated vapor phase G1 in the reactor pressure vessel 21 and a conductive portion 26b communicating with the aqueous phase L1 of the reactor, and the inside of the water measuring tube 26 is divided into gaseous phase G2 and which rises and lowers to reactor water level.

The water level measuring tube 26 is mounted outside the reactor pressure vessel 21, for example between the reactor pressure vessel 21 and the biological containment wall 37, and is formed by a vertical elongated tube. The water level measuring tube 26 is designed to withstand the reactor pressure vessel 21 under conditions of 20 (for example 72.1 kg / cm 2 * g and 287 ° C) and is made of stainless steel (SUS304 or SUS316, for example), carbon steel or the like. The total length of the water level measuring tube 26 is determined by the range of measurement of the water level in the reactor. The thickness of the water level measuring tube 26 is configured to prevent its wall from disintegrating as water consumes and decreases in thickness as a result of fluctuations in the liquid phase L2 level.

The water level measuring tube 26 has an inside diameter of several centimeters or less, for example 1 inch or less, to prevent the coolant from rising.

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The leakage from the reactor pressure vessel 21 and the water level measuring tube 26 acts as a pressure limiter as the upper conductive portion 26a and lower conductive portion 26b attached to the outer wall of the reactor pressure vessel 21 disintegrate.

| Further, to improve the response of the gas / liquid interface at the water level measuring tube 26 to fluctuations of the gas / liquid interface at the reactor pressure vessel 21 and reduce the accumulation of flammable non-condensable gas such as O2 and H2 is inclined 00 35 upwardly from the water level measuring tube 26 towards the reactor pressure vessel 21, and the lower conductive portion 26b is inclined downward from the water level measuring tube 26 towards the reactor pressure vessel 21.

The gas phase side detection unit (40a, 43a, 41) is kaasufaasipuo-len ultrasonic transducer 40a, the cable transmission unit 43a and the ultrasonic transmitter 41. The ultrasound-5 nilähetin 41 produces an electrical signal to ultrasonic transducers 40a and 40b by a predetermined period.

The gas phase side ultrasonic transducer 40a is placed in the water level of the MIT influx tube pass through an opening 26 formed in the water level in the measuring tube 26 upper end and fixed to conductive member 26a in the above paragraph. The gas phase 10 side of the ultrasonic transducer 40a and a feed opening (not shown) in the space between the periphery of the blank is sealed by welding in order to maintain the water level in the measurement pipe 26 and the reactor pressure vessel 21 of internal pressure.

The gas phase side ultrasonic transducer 40a includes a piezoelectric element (not shown). In response to the electrical signal from the ultrasonic transmitter 41, the piezoelectric element transmits an ultrasonic wave at a frequency from tens of Hz to several hundred kHz, and the ultrasonic wave propagates through the water level measuring tube 26 from the gas phase G2 to the liquid phase L2. The piezoelectric element also receives a reflection wave from the gas-liquid interface W1 and produces a reflection wave signal. The gas phase side ultrasonic transducer piezoelectric element 20 is made of a material 40a, which has a high thermal resistance and radiation resistance, such as lithium niobate.

Cable transfer unit 43a sends an electrical signal 41 produced by gas-phase ultrasonic transducer side of the ultrasonic transducers 40a. The cable transfer unit 43a also sends the produced gas phase side of the ultrasound transducer heijastusaal-25 signal of an ultrasonic transducer 41. The ultrasonic transmitter 41 transfers the received hello-jastusaaltosignaalin water level calculating unit 31. At least part of the cable transfer unit 43a-o near the gas phase side of the ultrasonic transducer 40a is mounted in a

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in a stable shielded tube filled with an inorganic insulating material having a high radiation shielding capability.

30 m liquid phase side detection unit (40b, 43b, 41) is a liquid phase side | an ultrasonic converter 40b, a cable transfer unit 43b, and an ultrasonic transmitter.

The liquid phase cm-side ultrasonic transducer 40b is fixed to the water-level measuring No G conductive portion 26b below the outer surface of the influx tube 26 in place of the liquid metal or the two power adapter. The liquid phase side 40b of the ultrasonic transducer 35 includes ^ a piezoelectric element (not shown). In response to the electrical signal from the ultrasonic transmitter 41, the piezoelectric element transmits an ultrasonic wave at frequency 11 from several MHz to several tens of MHZ, and the ultrasonic wave propagates through the water level measuring tube 26 from the liquid phase L2 to the gas phase G2. The liquid phase piezoelectric element side also receives reflection waves the gas-liquid interface W1 and produce heijastusaaltosignaalin. The gas phase side ultrasonic transducer 5 of the piezoelectric element 40a is made of a material having high thermal resistance and radiation resistance, such as lithium niobate. The cable transfer unit 43b has the same configuration as the cable transfer unit 43a.

The remote control unit (32, 33) has an information transmitting unit 32 and a remote control unit 33. The remote control unit 33 is connected to the water level calculating unit 31 via the information transmitting unit 32 to remotely control the water level calculating unit 31. The remote control unit 33 may be mounted so that it is not adversely affected by radiation. In this case, the information transmitting unit 32 is mounted to pass through the electrical passage (not shown) of the reactor container.

As shown in Figure 1, the float 58 is mounted in the water level measuring tube 26. Figure 2 is a diagram (in perspective) of the float 58. The float has a hollow cylinder shape which has an outer diameter larger than the opening width of the conductive portions 26a and 26b. The hollow structure provides the float 58 with sufficient lift to float in the liquid phase L2 in the water level measuring tube 26. Reference numeral 58a denotes a hollow 20 parts, reference numeral 58b denotes an inner surface, and reference numeral 58c denotes an outer surface. The float 58 is made of a material having high corrosion resistance and radiation resistance and capable of reflecting ultrasonic waves, such as stainless steel (e.g. SUS304 or SUS316).

The water level calculating unit 31 receives the reflection waves from the ultrasonic transducers 40a and 40b through the cable transfer units 43a and 43b and calculates the water level of the reactor based on the reflection wave signals.

5 The water level calculator 31 and the ultrasonic transmitter 41 are installed

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the main cab or outside the reactor vessel and coupled to the ultrasonic transducers 40a and 40b by cable transfer units 43a 43b which are inserted into openings 37a formed in the biological screening wall 37.

| In the boiling water reactor, the reactor coolant 25 circulates in the reactor pressure vessel 21, and the density of the coolant 25 varies between the water level measuring spout 26 and the reactor pressure vessel due to the velocity of the coolant circulating (velocity effect). The water level calculator 31 compensates for the difference in coolant density based on the value of reactor power supplied to it.

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In addition, the water temperature difference between the reactor pressure vessel 21 and the water level measuring tube 26 also causes a difference in the water densities therebetween. The water level calculating unit 31 also corrects this density based on the temperature difference.

In addition, in the case of a non-gas wave-liquid interface W1, the ultrasonic wave detection of a portion inside the water level measuring tube 26 sets a certain dead time for the ultrasonic signal processor.

The operation of the reactor water level measurement system 20 will now be described.

10 In the reactor water level measurement system 20, the ultrasonic transmitter 41 produces an electrical signal for a predetermined period. The electrical signal is supplied to the ultrasonic transducers 40a and 40b through the cable transfer units 43a and 43b.

The gas phase side ultrasonic transducer 40a transmits ultrasonic liquid phase L2 at a frequency of several tens Hz to several hundred kHz to flood page will incorporate an 15 receives reflection waves the gas-liquid interface W1 and heijastusaal-wave signal produced by receiving the reflection waves. On the other hand, the liquid phase side of the ultrasonic transducer 40b to the gas phase G 2 transmits the ultrasonic wave at a frequency of several MHz to several tens MHz flood page will incorporate an receives reflection waves the gas-liquid interface W1 and produce heijastusaaltosignaalin receiving the hi-20 jastusaallon.

The reflection wave signals produced from the ultrasonic transducers 40a and 40b are fed to the water level calculator 31 via the cable transfer units 43a and 43b, and the water level calculator 31 calculates the reactor water level through steps 1-3 described below.

25 Step 1: gas phase propagation time (t G) is calculated from the gas phase side of the ultrasonic transducer 40a transmits ultrasonic wave to the gas-phase five-side ultrasonic transducer 40a receives the reflection waves.

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^ In addition, the liquid side of the phase propagation time (t L) is calculated from the liquid phase in a half 40b of the ultrasonic transducer transmits the ultrasonic wave to the liquid phase 00 30-side ultrasonic transducer 40b receives the reflection waves.

| Step 2: Calculate the length of the gas phase according to the following formula (1) using the ultrasonic wave velocity VG (T) in the gas phase G2.

o | Lg = ~ V0 (1) O 1

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Further, the liquid phase length is calculated according to the following formula (2) 35 using the ultrasonic wave velocity V 1 - (T) in the liquid phase L 2.

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Ll = Y ^ 'l (2)

Step 3: The water level of the reactor is calculated from the gas phase length LG and the liquid phase length l_i_.

The gas phase length LG and 5 used to calculate the water level of the reactor water and the liquid phase length l_L are calculated from the propagation time of the ultrasonic gas phase G2 and the liquid phase cycle. This gives a good time resolution of the gas-liquid interface variation. For example, the reactor water level is immediately detected and measured when an anomaly occurs, such as when the reactor water circulation system pump system fails and when an earthquake or other accident occurs, or when the reactor pressure vessel 21 reactor water capacity changes, such as reactor activation. In addition, the water level of the reactor can be measured very accurately without an ultrasonic reflector installed in the water level measuring tube.

At frequencies from several MHZs to several tens of MHz, an ultrasonic wave is used to measure the liquid phase length L1. 15 within this range the frequencies of the ultrasonic waves propagate easily through the metal, and hence the liquid-phase side of the ultrasonic transducer 40b need not be positioned in the liquid phase L2, but it can be installed in the water level in the measuring tube 26 outside. Accordingly, the liquid-phase side of the ultrasonic transducer can be attached to and maintained easily, and nestefaasipuo-len ultrasonic transducer 40b due to radiation degradation can be reduced. As the frequency of the ultrasonic wave increases, the accuracy of the measurement improves, although the ultrasonic wave attenuates more in the gas phase G2. Thus, in the measurement of the gas phase length LG, from the point of view of reducing the ultrasonic wave attenuation, the frequency of the ultrasonic wave is preferably set from several tens of Hz to several hundreds of kHz.

Furthermore, since the water level measuring tube is installed outside the reactor pressure stage Tian 21, the internal temperature of the water level measuring tube 26 is slightly lower than the internal temperature of the reactor pressure vessel 21, and thus the saturated vapor content of the gas phase G2 is reduced. As a result, the gas-liquid interface disturbances of the liquid phase L2 00 and the horizontal and vertical fluctuations of the float 58

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£ 30 is reduced so that the water level can be measured with greater reliability.

In addition, ultrasonic transducers 40a and 40b and other components do not need to be installed in a reactor pressure vessel 21 having extreme environmental conditions including high temperature, high pressure and high level of radioactivity. In addition, the ultrasonic transducers 40a and 40b and other components 35 do not require a control mechanism. Thus, the reactor water level measurement system 14 and the reactor are simplified, and the deterioration of the water level measurement reliability and reactor power stability due to the deterioration of the structures is reduced.

(Second Embodiment) Figure 3 is a diagram illustrating a reactor water level measurement system according to another embodiment. The reactor water measuring system according to this embodiment is a modification of the reactor water measuring system 20 according to the first embodiment, the same parts as in the first embodiment are denoted by the same reference numerals and their descriptions 10 are omitted. Modified or new parts shall be identified by reference numbers bearing an "A".

As shown in Figure 3, the reactor according to this embodiment of the water in the measuring system 20A is the water level in the measurement pipe 26A, the gas-phase side of the detection unit (27A, 28A, 29A, 30A), the liquid phase side of the detection unit (40b, 43b, 41), the temperature calculating unit 59Aja remote control ( 32A, 33A). Figure 4 is a diagram (in perspective) of a water level measuring tube 26A.

To increase the surface area to improve the thermal radiation effect, the water level measuring tube 26A has a plurality of barbs 57A on the outer surface as shown in Figure 4.

The studs 57A are designed to withstand conditions near the reactor pressure vessel 20 21 (e.g., an internal pressure of 72.1 kg / cm 2 * g and a temperature of 287 ° C) and are made of stainless steel (SUS304 or SUS316, for example) or carbon steel. The studs 57A are welded to the water level measuring tube 26A. The number of barbs 57A can be any one considering the effect of thermal radiation.

25 Gas-phase half-detecting unit (27A, 30A, 28A, 29A) is a microwave

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£ source 27A, antenna unit 29A and cable transfer unit 28A.

The microwave source 27A produces a microwave. For example, a microwave source? V 27A contains an electron tube such as a klystrone, a magnetron and a waveguide, or a semiconductor device such as a GUNN diode. The microwave frequency is less sensitive to ab- | 30 for sorption or scattering in steam, for example, at a frequency from several GHz to several tens of GHz. The microwave source 27A and the water level measuring tube 26A are heat-emitted and electrically insulated.

The microwave detection unit 30A detects the reflected microwave and produces a reflection wave signal. For example, the microwave detection unit 30A includes a detection element such as a detection diode, a bolometer, and a thermistor.

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The antenna unit 29A transmits the microwave generated by the microwave source 27A to the liquid phase through the gas phase in the water level measuring tube 26A, and receives a reflection wave from the gas-liquid interface W1. The antenna unit 29A is made of a metal material which has a high thermal resistance and a high radiation resistance and is an electromagnetic horn or parabolic antenna unit. The antenna unit 29A is disposed in the gas phase G2 through an inlet formed at the upper end of the water level measuring tube 26A, and the gap between the antenna unit 29A and the inlet opening is completely sealed by welding or the like.

The cable transfer unit 28A serves as a transmission path for the microwave and reflection wave between the microwave source 27A and the antenna unit 29A. The cable transfer unit 28A is made of a metal material of high thermal resistance formed of a hollow conductor capable of transmitting microwave at high efficiency and having a circular or rectangular cross-section.

The liquid phase side detection unit (40b, 43b, 41) is the same as Ensim 15 in the first embodiment, and a description thereof will be omitted.

The temperature calculator 59A may communicate with the water level calculator 31 via a wire or a radio path. The temperature calculating unit 59A calculates the internal temperature of the water level measuring tube 26A according to the following formula (3).

20 tG-V (; (t) + t L-V L {t) 2 tG: microwave propagation time in gas phase G2 from the transmission of the microwave by the antenna unit 29A to the reception of the reflection wave by the antenna unit 29A.

t1: the propagation time of the ultrasound wave in the liquid phase L2 from the transmission of the ultrasound transducer 40b to the reception of the reflection wave by the ultrasound transducer 40b.

0 7 T: internal temperature of water level measuring tube 26A, c0 Vg (T): microwave velocity in gas phase of water level measuring tube 1 26A only as a function of internal temperature T of water level measuring tube 26A.

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30 Vl (T): ultrasonic wave velocity in liquid phase in water level measuring tube 26A as a function of internal temperature T of water level measuring tube 26A only.

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° L: sum of the gas phase length and the liquid phase length in the water level measuring tube 26A (known value).

The water level calculator 31 calculates the water level of the reactor in the same steps 1 to 3 as in the first embodiment, using the microwave speed Vg (T) for gas phase G2 in the water level measuring tube 26A and the ultrasonic wave velocity L2 for the 59A from the internal temperature T of the water level measuring tube 26A.

In some cases, however, the microwave transmitted from the upper end of the water measuring tube 26A to the gas-liquid interface W1 or the ultrasonic wave transmitted from the lower end of the water measuring tube 26A to the gas-liquid interface W1 may be diffused before the gas-liquid interface W1 can receive a scattered microwave or ultrasound wave.

The scattered reflected microwave or ultrasonic wave travels a shorter distance than the reflected microwave or reflected ultrasonic wave at the gas-liquid interface W1 of the coolant, and is thus detected rather than the reflected microwave or ultrasonic wave. Fragmented reflected microwave or ultrasonic wave 15 is eliminated by utilizing this fact. In particular, the water level calculating unit 31 is configured to use a certain dead time to remove any waves detected prior to the reflection microwave or ultrasonic wave from the gas-liquid interface W1 of the coolant. In this way, the microwave and ultrasonic wave reflected from the gas-liquid interface W1 are separated from the scattered microwave and the ultrasonic wave, and the microwave and ultrasonic wave reflected from the water level measuring tube 26A other than the gas-liquid interface is dispersed.

The water level counting unit 31, the temperature counting unit 59A, the microwave source 27A, and the microwave detection unit 30A are mounted in the main cockpit 25 or outside the reactor pressure vessel 21. These elements are connected to the antenna 29A and the liquid phase side of the ultrasonic transducer 40b, the cable transfer unit 28A and 43b, which are 5-propelled biological protection wall 37 through the openings 37a.

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The remote controller (32A, 33A) has an information transmitting unit 32A and a v remote control unit 33A. Like the remote control unit 33 in the first embodiment, the remote control unit 33A can remotely control the water level calculation | unit 31. The remote control unit 33A is further coupled to a microwave source cm 27A, a microwave detection unit 30A, and a water level calculating unit 31 with an information transmission unit 32A, and can remotely control some of these devices. you or the whole device. The remote control unit 33A may be mounted outside the reactor vessel ™ 35 so that it is not adversely affected by radiation. In this case, the information transmitting unit 32A is installed to pass through the electrical passage (not shown) of the reactor container.

For the boiling water reactor, the temperature of the coolant varies between the water level measuring tube 26A, which serves as a reference branch exposed in a dry source, and the reactor pressure vessel 21, and therefore also the density of the coolant. Although the microwave detection unit 30A detects a microwave signal reflected from the gas-liquid interface W1 in the water level measurement tube 26A, the water level in the water level measurement tube 26A may be inaccurately measured due to variation in coolant density.

10, the microwave detection unit 30A calculates the water level (gas-liquid interface W1 level) in the water level measuring tube 26A, i.e. the reactor water level of the reactor pressure vessel 21 by making the necessary temperature and density adjustments for the reflected reflection microwaves eliminates the effect of diffused reflected waves in the water level measuring tube 26A. The microwave detection unit 30A corrects the density based on the difference in water temperature between the reactor pressure vessel 21 and the water level measuring tube 26A.

The reactor water level measurement system 20A will now be described

activity.

In the reactor water level measurement system, a microwave source 27A

produces a microwave for a preset period. The microwave is transmitted to the antenna unit 29A via the cable transfer unit 28A. In addition, an ultrasonic transmitter 41 mounted outside the reactor pressure vessel 21 produces an electrical signal for a preset period. The electrical signal is supplied to the liquid phase side 40b, an ultrasonic transducer cable 25 via the transfer unit 43b.

The antenna unit 29A transmits at a microwave frequency from several GHz to several tens of GHz to liquid phase L2 and receives gas-liquid

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^ at the interface W1 a reflection wave. The reflection wave is supplied to the microwave detection unit 30A via the cable transfer unit 28A. In normal operation the reactor 00 30 pressure vessel 21 has a core of high temperature and high pressure environment, and | therefore, cooling water and steam may mix and the intensity of detection may decrease.

In this case, the remote control unit 33 changes the frequency of the microwave so that the transmission loss of the microwave is reduced, thereby increasing the intensity of the detected signal.

When the detected signal is weak, the detection result displayed on the display of the water level calculator 31 (not shown) exhibits a point of discontinuity P 18 as shown in FIG. The discontinuity point P represents the interface between two different di-electrical constant phases, especially the vapor phase and the aqueous phase, more particularly the gas-liquid interface W1 in this case.

When it is difficult to identify a point of discontinuity, the microwave source 27A is adjusted to change the frequency of the microwave to make a discontinuity point identifiable as described above. The water level can be determined from the microwave propagation rate and the time at which the point of discontinuity P occurs.

The determined water level as well as time, location, microwave source 27A settings, and any other necessary information are communicated via the information transmitting unit 32A to the main cockpit or any other location outside the controlled area and displayed on the display unit (not shown) level and any other information is effectively and economically available at that location.

15 On the other hand, the liquid phase side 40b of the ultrasonic transducer transmits the ultrasonic wave at a frequency of several MHz to several tens MHz flood page will incorporate an gaseous phase G2 receives the reflection waves the gas-liquid interface W1 and produce refl-tusaaltosignaalin receiving the reflection waves. The reflection wave signal is supplied to the water level calculating unit 31 via the cable transfer unit 43b.

In a vapor environment, the ultrasonic wave oscillated by the ultrasonic transducer 40b may be diffused and thus attenuated, which may have a detrimental effect on the measurement. However, in the reactor water level measuring system, the ultrasonic wave is oscillated at the lower end of the water level measuring tube 26A and propagates through the water and therefore the attenuations are reduced.

The temperature calculating unit 59A calculates the microwave gas phase propagation time from the time the microwave source 27A generates the microwave to the microwave detection unit 30A receiving the reflection wave signal as an example. In addition, the temperature calculating unit 59A calculates the liquid phase propagation time ti of the ultrasound wave. the time between the time when the ultrasonic converter 41 produces the electrical signal, 00 and the time when the reflection wave signal is received on the basis. Then the formula (3)

| accordingly, the temperature calculating unit 59A calculates the water level measuring tube 26A

cvj internal temperature, o g The water level calculating unit 31 then calculates the ultrasonic wave velocity V1 (T) in the liquid phase L2 based on the internal temperature of the water level ^ 35 measured by the water calculating unit 26A calculated by the temperature calculating unit 59A. Then, using the speed of the ultrasound wave V1 (T), the water level of the reactor is calculated in the same steps 1 to 3 as described in the first embodiment.

In addition to the advantages (1) to (3) of the first embodiment, the reactor water level measurement system 20A has the advantages described below.

Because the water level measuring tube 26A has barbs 57a on the outer surface, the water level measuring tube 26A has a larger surface area and improved heat radiation. As a result, the internal temperature of the water level measuring tube 26A is lower than the internal temperature of the reactor pressure vessel 21, and the vapor volume of the gas phase G2 is reduced such that microwaves are less likely to scatter or subside and the water level is more reliably measured.

(Third Embodiment)

Figure 6 is a diagram illustrating a reactor water level measurement system according to a third embodiment. The reactor water level measuring system according to this embodiment is a modification of the reactor water level measuring system 20 according to the first embodiment. The same parts as in the first embodiment are denoted by the same reference numerals and their description is omitted. Modified or new parts are identified by an additional 'B' in the reference numerals.

according to this embodiment, the water level of the reactor mittausjär-20 SYSTEM 20B is a gas phase side of the detection unit (27B, 28B, 29B, 30B), NES tefaasipuolen detection unit (40bB, 43bB, 41), temperature calculation unit 59B and the gas-liquid interface in the reading unit (60B; 61B, 62B, 63B). The gas phase side detection unit, the liquid phase side of the detection unit and the temperature calculating unit are the same as in the second embodiment, and the description thereof will be omitted. 25 The gas-liquid interface of the reactor water level measuring system 20B

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The £ nan read position unit has a magnetized float 60B, a float guide waveguide ™ 61B, a float position reader 62B, and a cable transfer unit 63B.

Fig. 7 is a diagram (in perspective) of a magnetized float. magnesium

cö the floated float 60B has the shape of a hollow donut and contains a hollow portion 60aB

| 30 magnetized parts. For example, the magnetized part consists of a magnet. Reference numeral 60bB denotes the outer surface, and reference numeral 60cB denotes the inner surface, o The magnetized float 60B is mounted on the water level measuring tube 26, and

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? the diameter is greater than the width of the openings in the conductive portions 26a and 26b of the water level measuring tube 26.

The float guide waveguide 61B is formed of a hollow tube made of a metal material having a high heat resistance, including a waveguide for the microwave transmitted from the antenna unit 29B. The float guide on the waveguide 61B has an opening (not shown) that allows gas or liquid in the water level measuring tube 26 to drain into the float guide on the waveguide 61B. The float guide waveguide 61B is secured by welding, for example, the portion 5 of the antenna unit 29B disposed in the water level measuring tube (see section P in Figure 6).

Fig. 8 is a diagram (longitudinal cross-sectional view) of a float position reader 62B. The float position reader 62B has a housing 62aB, a plurality of magnetic frames 62bB, and a mounting magnetic frame 62cB, and is disposed along the outer surface of the water level measuring tube 26. The float position reader 62B is configured to produce a float position signal in response to the magnetism of the magnetic float 60B.

The magnetic frames 52bB and the mounting magnetic frame 62cB are mounted in the housing 62aB. The magnetic bodies 62bB are oriented in one direction by the magnetic force of the magnetic body 62cB, and are supported to be horizontally rotatable in response to the magnetic force of the magnetic float 60B. The float position reader 62B generates a float position signal as the magnetic bodies 62bB rotate horizontally in response to the magnetic float magnetic force and transmits the signal through the cable transfer unit 63B. The float position reader 62B is configured to provide a float position signal 20 when the float position indicator portion (not shown) detects rotation of the magnetic bodies 62bB by mechanical contact or an optical unit.

The cable transfer unit 63B transmits the generated float position signal to the water level calculator 31. The water level calculator 31 calculates the position of the gas-liquid interface W1 and the float position signal received through the reactor water level cable transfer unit 63B 25.

The reactor water level measurement system 20B will now be described

5 activities.

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In the reactor water level measuring system 20B, the microwave source v 27B produces a microwave over a preset period. The microwave is transmitted to the antenna unit 29B via the cable transfer unit 28B. Antenna unit 29A transmits | at a microwave frequency from a plurality of GHz to a plurality of tens of GHz of a float c \ j guide to the liquid phase L2 in the waveguide 61B and receive a reflection wave

g Ion from the gas-liquid interface W1. The reflection wave received by the antenna unit 29B is fed to the microwave detection unit 30B by the cable transfer unit 28B

00 35. The reactor water level is then calculated in the same process as in the second embodiment.

21

On the other hand, in the position reading unit of the gas-liquid interface (60B, 61B, 62B, 63B), the magnetic body 62bB against the magnetized float 60B rotates in response to the magnetic force of the magnetized float 60B, and the float position signal is produced in response to rotation. The float position signal is supplied to the water level calculator 31 via the cable transfer unit 63B. The water level calculating unit 31 then calculates the water level of the reactor based on the float position signal by a predetermined rule.

Reactor water level measurement systems according to first to third embodiments of the invention have been described above. However, the present invention is not limited to certain configurations of these embodiments, and various modifications and additions may be made to the design without departing from the spirit of the invention. For example, components of reactor water level measurement systems of various embodiments may be used in combination.

Alternatively, the water level measuring tube may be a window providing an inside view thereof, the imaging device for capturing a float in the water measuring tube may be arranged outside the water measuring tube, and the reactor water level may be lowered from the float position in the image.

Alternatively, radiation such as X-rays and neutron radiation can be used and transmitted to the water level measuring tube to take a picture of the float in the water level measuring tube 20 and reactor water level can be calculated from the position of the float in the image.

Further, the magnetized float described above is formed by placing a magnetized portion in the float. Instead, the float itself may be formed of a magnetic body. Alternatively, the float may produce an acoustic wave for a predetermined period, and the float position may be detected by detecting an acoustic wave.

In addition, the water level calculating unit 31 may perform a process to improve the reliability of the water level measurements, such as time correlation,

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Frequency analysis of changes, measurement of water level certification by reactor T water level wave analysis and estimation by checking the reactor water level 00 30 tables. In addition, the water level calculating unit 31 can correct the length of the gas phase and the length of the liquid phase according to environmental conditions such as temperature, pressure, and dose, o g. back-up systems are used for the boiling water reactor. However, the uses of the invention are not limited to the boiling water reactor.

(Fourth embodiment) 22

A fourth embodiment of the present invention will now be described with reference to the figures. Fig. 9 is a schematic longitudinal cross-section of a reactor pressure vessel water level measuring tube to which a fluid level measuring system according to this embodiment is connected. As shown in Fig. 9, the boiling water reactor pressure vessel is provided with an upper tube 120, a lower tube 130 and a water level measuring tube 140 which interconnect the upper tube 120 and lower tube 130 to measure the water level in the pressure vessel. A plurality of ultrasonic transceiver units 112 are mounted on the lateral surface of the water level measuring tube 140. The reactor pressure vessel 100 contains water that acts as a coolant.

Referring to Figure 10, a configuration of a liquid level measurement system of the present invention is described. Fig. 10 is an enlarged longitudinal cross-section of a water level measuring tube to which a fluid level measuring system according to this embodiment is connected. The ultrasonic transceiver-15 units 111a, 111b and 111c are attached to the side surface of the water level measuring tube 140. The ultrasonic transceiver units 111a, 111b and 111c are arranged on one side of the water level measuring tube 140 along its axis. The ultrasonic transceiver units 112a, 112b and 112c are mounted on a side surface 20 opposite to the ultrasonic transceiver units 111a, 111b and 111c of the water level measuring tube 140. The ultrasonic transceiver units 111a, 111b and 111c and the ultrasonic transceiver units 112a, 112b and 112c are arranged opposite each other on opposite sides of the water level measuring tube 140.

The ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 112c transmit an ultrasonic pulse to the water level measuring tube 140 and receive 25 ultrasonic reflection waves from the inner walls 140a and 140b of the water level measuring tube 140. In addition, the ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b, and 112c receive the ultrasonic transceiver unit facing them, transmitting this ultrasonic pulse transmitted through the water level measuring tube 140. For example, the ultrasonic transceiver unit 111a receives its own transmitter 00 from the inner walls 140 and 140b of the reflection wave of this ultrasonic pulse as well as the ultrasonic pulse transmitted by the ultrasonic transceiver unit 112a. Although Fig. 10g shows only three pairs of ultrasonic transceiver units 111a, 111b, 111c, 112a, §112b and 112c, the number of ultrasonic transceiver units is not limited to any particular value, but the number of ultrasonic transceiver units can be grow. The axial distance between the ultrasonic transceiver units is an indicator of the accuracy of the water level measurement, and the number of axially arranged ultrasonic transceiver units is an indicator of the water level measurement interval. Thus, for example, the number of ultrasonic transceiver units can be determined by taking into account the accuracy and measurement interval of the water level measurement. Alternatively, the number of ultrasonic transmitter-5 receiver units may be determined based on the number of waterline lines marked on the water level measuring tube 140. Alternatively, one pair of ultrasonic transceiver units may be arranged in each of two locations above and below the current water level.

The ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 10 112c are mounted on a control unit 121 which transmits an electrical signal and receives an electrical signal from each ultrasonic transceiver unit. Modulator unit 122 is mounted between the ultrasonic transceiver unit and the control unit. Modulation unit 122 modulates the amplitude, duration, and number of cycles of the electrical signal transmitted from the control unit 121 to the ultrasonic transceiver unit. The control unit 121 is coupled to the water level calculating unit 123, which determines whether the inside of the water level measuring tube is a gas phase or a liquid phase, based on the signal received from the ultrasonic transceiver unit.

The electrical signal transmitted from the control unit 121 to the ultrasonic transceiver unit 20 is a signal that instructs the ultrasonic transceiver unit to transmit an ultrasonic wave (hereinafter referred to as a command signal). The electrical signal received by the control unit 121 from the ultrasonic transceiver unit is a signal produced when the ultrasonic transceiver unit receives an ultrasonic wave (hereinafter referred to as the receiving signal).

The control unit 121, the modulation unit 122 and the water level calculating unit 123 are mounted outside the reactor pressure vessel such as the main cab 5 or outside the controlled area. Control unit 121, modulation unit 122 and

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The water level calculating unit 123 is electrically coupled to transmit electrical signals to the ultrasonic transceiver unit and to receive electrical signals from the ultrasonic transceiver unit 00 through a container-passing tube.

The upper tube 120, the lower tube 130, and the water level measuring tube 140 are made of stainless steel, nickel-based alloy, low-gauge cassette steel, carbon steel or the like. Water level measuring tubes-? The overall length of the ken 140 is determined by the desired water level measurement interval. The inside diameter of the water level measuring tube is not limited to any particular value.

The outer diameter of the water level measuring tube 140 is determined such that the water level measuring tube 140 is not damaged or broken even under abnormal conditions of high temperature or high pressure. The upper tube 120 and the lower tube 130 have no limit to the outer diameter, inner diameter, or length. The upper tube 120 and lower tube 130 are inclined to prevent the accumulation of non-condensable gas. Although the water level measuring tube 140, the upper tube 120 and the lower tube 130 have a circular cross-section in this embodiment, these tubes may have any internal and external shape such as an oval shape or a polygonal shape. More specifically, these tubes may have a circular inner cross-section and a hexagonal outer cross-section. In addition, the water level measuring tube 140, the upper tube 120 and the lower tube may have different internal and external cross sections depending on the part. For example, the water level measuring tube 140 may in principle have a circular shape, and only parts having ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 112c may have a polygonal shape such that the ultrasonic transceiver units 111a, 1511b, 111c, 112a, 112b and 112c can be coupled to a planar surface.

The ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b, and 112c are ultrasonic transducers that form a heat-resistant and radiation-resistant material such as a lithium niobate oscillator. The ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 112c are attached to the inner surface of the water level measuring tube 140 through a metal or liquid medium. The frequency of the ultrasonic pulse is set between several hundreds of kHz and several hundred MHz, so that the ultrasonic pulse can pass through the water level measuring tube 140 and the liquid phase. The ultrasonic sensors may be separate oscillators or a common oscillator array such as a phased array sensor.

The control unit 121 has a high voltage generating circuit which provides a command signal to the ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 112c, and a voltage amplification circuit which detects an ultrasonic transmitter.

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a receiving signal from the receiver units 111a, 111b, 111c, 112a, 112b and 112c.

The modulation unit 122 is a voltage modulation circuit connected to a | a high voltage generating circuit of the sensing unit 121 and generating a pulse which is produced by varying the voltage, duration, and number of cycles of the electrical signal. The ultrasonic pulses transmitted from the ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 112c are determined by the voltage of the command signal or the like. Therefore, the modulation unit 122 modulates the command signal thereby modulating the ultrasonic pulses transmitted from the ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 112c. Modulation unit 122 may individually modulate the command signal transmitted to each ultrasonic transceiver unit. Thus, the ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b and 112c can transmit ultrasonic pulses at different frequencies, amplitudes and the like.

The water level calculating unit 123 determines whether the inner gas phase of the water level measuring tube 140 is only a liquid phase by calculating on the basis of the reception signal detected by the voltage amplification circuit of the control unit 121 and determining the presence or absence of reflection and transmitted waves in each ultrasonic transceiver. For example, the water level calculating unit 123 performs a calculation of the receiving signal of the ultrasound transceiver unit 111a to determine whether the signal received by the ultrasound transceiver unit 111a is self-transmitting and reflecting from the inner wall 140a 140 transmitted waves (near-15 waves). If the reception signal contains a significant amount of noise, preprocessing such as noise reduction or waveform discrimination is performed using an analog or digital filter circuit or frequency filtering software before determining whether the ultrasonic wave is a reflection wave or a transmission wave.

The ultrasonic pulse experiences multiple reflections or deformations in the wall of the water measuring tube 140, the liquid phase in the water measuring tube 140 and the like. However, the determination can be made using a reflection wave or a transmitting wave that has undergone multiple reflections or deformations. However, in the following description of this embodiment, it is assumed that the reflection wave and the transmitting wave do not experience multiple reflections or deformations.

The water level calculating unit 123 may be implemented as a computing program or application specific hardware included in a conventional computer.

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In particular, the operation of the liquid level measuring system of this embodiment will now be described. First, with respect to the ultrasonic transceiver unit 111a, reference will be made, with reference to Figure 11, to the measurement of the water level using | This reflects the reflection waves from the inner walls 140a and 140b. Figures 11 are enlarged diagrams of Fig. 10c and showing paths of ultrasonic pulses transmitted from an ultrasonic transceiver unit 111a to g and their reflection waves. Figures 11 (a) and 11 (b) show different water levels. Several components are not shown in these figures.

The command signal from the control unit 121 is modulated by the modulation unit 122, and the modulated command signal is transmitted to the ultrasonic transceiver unit 111a. The ultrasonic transceiver unit 111a transmits an ultrasonic pulse 131a to the water level measuring tube 140.

As shown in Fig. 11 (a), when the reflection point of the ultrasonic pulse 131a on the inner wall 140a is in the gas phase in the water level measuring tube 140, the ultra-5 pulse 131a does not pass through the inner wall 140a and the ultrasonic transceiver unit 111a receives a reflection wave 131b from the inner wall 140a. The term '' reflection point '' refers to a point on the inner wall of a water level measuring tube 140 from which an ultrasonic pulse 131a is reflected.

On the other hand, as shown in Figure 11 (b), when the reflection point of the ultrasonic pulse 131a 10 on the inner wall 140a is in liquid phase in the water level measuring tube 140, the ultrasonic pulse 131a is partially reflected from the inner wall 140a and partially passes through the inner wall 140a. The ultrasonic pulse 131 entering the liquid phase then reaches and is reflected by the inner wall 140b. The ultrasonic transceiver unit 111a receives the reflection wave 131b from the inner wall 140a and the reflection wave 131c from the inner wall 140b.

The water level calculating unit 123 performs a calculation for the reception signal received from the ultrasonic transceiver unit 111a of the control unit 121 and determines whether the ultrasonic wave received by the ultrasound transceiver unit 111a includes a reflection wave 131b and a reflection wave 131c. In particular, noise is first removed from the receiving signal by frequency filtering. Then, reflection waves 131b and 131c are identified based on the ultrasonic pulse modulation mode or detection time. Since the ultrasonic pulse is modulated individually for each ultrasonic transceiver unit, it is possible to determine which ultrasonic transceiver unit has transmitted an ultrasonic pulse from which the relevant reflection wave is derived based on the frequency of the 25 ultrasound waves or the like. Further, because the reflection waves 131b and 5 131c of the ultrasonic pulse transmitted from the ultrasonic transceiver unit 111a travel along paths of different lengths before being received by the ultrasonic transceiver.

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In the hin receiver unit 111a, the reflection wave 131c is received after the reflection wave 131b. Thus, based on the ultrasonic pulse modulation mode or detection time, reflection waves 131b and 131c can be identified.

| Figure 12 shows an example of a reception signal. Fig. 12 (a) illustrates a receive signal when the reflection point is in the gas phase, and only the reflection wave g 131b exists. Figure 12 (b) shows a reflection signal when the reflection point is in the liquid phase, and both reflection waves 131b and 131c exist. In both 00 35 in Fig. 12 (a) and 12 (b), the y-coordinate indicates the intensity of the signal amplitude, and the x-axis indicates the time.

27

As the reflection point is in the gas phase, as shown in Fig. 12 (a), a single amplitude increase is observed, which indicates ultrasonic wave reception. Figure 12 (b) again shows two amplitude bumps indicating ultrasonic wave reception. The first amplitude bump indicates the reflection wave 131c, and the second amplitude bump indicates the reflection wave 131c. Other signals are noise. As can be seen, the amplitude gain indicating the reception of the reflection wave 131b is smaller in Figure 12 (b) than in Figure 12 (a).

A binary determination is then performed. Specifically, a threshold is set for the amplitude of the received signal, and it is determined that the ultrasonic wave is received if the waveform amplitude is greater than the threshold, and that the ultrasonic wave is not received if the waveform amplitude is less than the threshold. The threshold is suitably set so that noise is not detected as a reception signal, and when receiving a reflection wave, the received reception signal is detected as a reception signal without error. In other words, the threshold is set to a value that the noise 15 does not exceed but the receive signal exceeds. If the binary determination indicates that there is no reflection wave 131c, it is determined that the reflection point is in the gas phase. If the binary determination indicates that the reflection wave 131c exists, it is determined that the reflection point is in the liquid phase. When the reflection point is in the liquid phase, the threshold may be greater than the amplitude of the reflection wave 131b if the amplitude of the reflection wave 131b is smaller than the amplitude of the reflection wave 131c, as shown in Fig. 12 (b). This is because it is important to determine the presence or absence of the reflection wave 131c, and it is only essential that the amplitude of the reflection wave 131c is greater than the threshold.

Binary detection can avoid misidentification of other weak signals caused by noise or ultrasound wave as reflection waves 131b or 131c.

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As an alternative to the binary determination described above, determining whether the reflection point is in the gas phase or the liquid phase can be determined by comparing the reception signals of the reflection waves 131b and 131c.

In particular, it is assumed that the reception signal of the reflection wave 131b is denoted Ua,

The reception signal of the reflection wave 131c is denoted LT a and the amplitude ratio V

c \ j is determined according to the following formula (4).

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§ V = (U'a) / Ua (4) ° A threshold is then set for the specified amplitude ratio V, and a binary determination is performed using the threshold. If it is determined that the reflection point is in the gas phase if V = 0, and that the reflection point is in the liquid phase if V = 1. The amplitude ratio determination of the reception signals can be used in combination with the method using the reflection wave 131b or 131c described above. Using multiple determination criteria together can improve measurement reliability.

As described above, whether the reflection point is in the gas phase or the liquid phase can be determined by determining whether the ultrasonic transceiver unit 111a receives reflection waves from the inner walls 140a and 140b. Since the determination is not based on the reflection of the ultrasonic waves, the determination is less influenced by the state of the inner surface of the water level measuring tube 140, thus providing good reliability with the uneven surface of the measuring level 140

The determination using the reflection waves described above can be done using a single ultrasonic transceiver unit. In addition, the wave 15 transmitted through the inner wall 140b and reflected from the outer surface of the water level measuring tube 140 may also be used instead of the reflection wave 131c.

Similarly, the ultrasonic transceiver units 112a, 112b, and 112c are determined to have a reflection point in the gas phase if the computation by the water level calculating unit 123 indicates that no reflection wave has been received from the inner wall 140a or transmitted through the inner wall 140a and determining that the reflection point is in the liquid phase if the result of the calculation indicates that this reflection wave has been received.

Finally, the water level calculating unit 123 performs this determination on all ultrasonic transceiver units mounted on the water level measuring tube 140 along its axis and determines the water level based on the results. For example, if the assay results for the ultrasonic transceiver units 111a and 5 112a indicate that the reflection point is in the gas phase, and the assay results

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The ultrasonic transceiver units 111b, 111c, 112b and 112c indicate that the reflection point is in the liquid phase, the water level is located between the ultrasonic transceiver unit 111a and the ultrasonic transceiver unit 111b. Thus water | As the number of ultrasonic transceiver units mounted along the axis of the son measuring tube 140 increases, the water level can be measured more reliably, og The axial distance between the ultrasonic transceiver units is thus an indicator of the water level measurement accuracy and the number of ultrasonic transducer units is 35 indicator. When the ultrasonic transceiver units 111a, 111b, 111c, 112a, 112b, and 112c are mounted as needed on the water level lines 140 on the water level measuring tube 140, the liquid level measurement method is intended to indicate whether the water level reaches each of the designated water level lines. When the ultrasonic transceiver units 111a, 111b, 112a and 112b are installed above and below the current water level, the liquid-5 level measurement method is intended to indicate whether the water level is changing. The axial distance between the ultrasonic transceiver units 111a and 111b and the ultrasonic transceiver units 112a and 112b is an indicator of the accuracy of detection of whether the water level changes or not.

Next, a measurement of the water level using the opposite wave emitted from the ultrasonic transceiver unit, associated with the ultrasonic transceiver units 111a and 112a, will be described. FIG. 13 are enlarged diagrams of FIG. 10 showing paths of ultrasound pulses transmitted from the ultrasound transceiver unit 111a. Figures 13 (a) and 13 (b) show different water levels. Several components are not shown in these figures.

Ultrasonic transceiver unit 111a transmits ultrasonic pulse 131a to water level measuring tube 140. In particular, if the ultrasonic transceiver unit is a phased array sensor, the transmission angle of the ultrasonic pulse 131a can be controlled by adjusting the phase of each phased array sensor.

As shown in Figure 13 (a), when the transmitting point 20 of the ultrasonic pulse 131a on the inner wall 140a is in the gas phase, the ultrasonic pulse 131a does not pass through the inner wall 140a and thus does not reach the ultrasonic transceiver unit 112a. The term '' transmitting point '' refers to a point on the inner wall of the water level measuring tube 140 where the ultrasonic pulse 131a passes through the inner wall. The transmission point is practically the same as the reflection point.

On the other hand, as shown in Fig. 13 (b), when the transmitting point of the ultrasonic pulse 131a on the inner wall 140a is in the liquid phase, the ultrasonic pulse 131a passes partially through the inner wall 140a and inner wall 140b and reaches the ultrasonic transmitter.

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the receiver unit 112a. The ultrasonic pulse transmitted from the ultrasonic transceiver unit 111a and reaching the 17 ultrasonic transceiver unit 112a is called the 00 30 transmitting wave 131d. In Fig. 13 (b), the description of the reflection wave of the ultrasonic pulse from the inner walls 140a and 140b is ignored.

The water level calculating unit 123 determines whether or not the transmitting wave 131 d0 g is received from the signal received from the ultrasonic transceiver unit 112a of the control unit 121. In particular, noise is removed from the receiving signal by frequency filtering, and transmitting wave 131d is identified based on the ultrasonic pulse modulation mode or detection time.

30

In the above-described determination using reflection waves, both reflection waves received by the ultrasonic transceiver unit 111a from the inner walls 140a and 140b are derived from the ultrasonic pulse transmitted by the ultrasound transceiver unit 111a. In the determination using a transmitting wave, the transmitting wave 131d achieved by the ultra-5 audio transceiver unit 112a is derived from the ultrasonic pulse transmitted by the ultrasonic transceiver unit 111a. On the other hand, since the diameter of the water level measuring tube 140 is known, the time from the time the ultrasonic transceiver unit 111a transmits the ultrasonic pulse to the ultrasound transceiver unit 112a detecting the transmitting wave 131d can be estimated. Thus, the transmitting wave 131d can only be identified by its modulation state or detection time. Additionally, if both modulation mode and estimated detection time are used simultaneously, the transmit wave 131d can be more reliably identified.

The threshold used in the binary determination is then set to the amplitude of the receive signal. It is determined that the transmission point is located in liquid phase-15 if the result of the binary determination indicates that a transmission wave 131d is found. On the other hand, it is determined that the transmit point is in the gas phase if the result of the binary determination indicates that no transmit wave 131d exists.

As an alternative to the binary determination described above, the binary determination may be performed by determining the amplitude ratio V 'of the amplitude U' a of the receiving signal transmitting wave 20 131d and the amplitude Ua. It is then determined that the transmission point is in the gas phase if V '= 0, and it is determined that the transmission point is in the liquid phase if V' = 1.

If the determination using a transmitting wave from the opposite ultrasonic transceiver unit is used in conjunction with the determination using reflection waves in this manner, the number of determination criteria is increased and thus the determination can be made more reliably.

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5 The above-described assignment using a waveform can be made for each

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^ to a pair of ultrasonic transceiver units. Alternatively, the determination can be made for each paired ultrasonic transceiver unit. More precisely, the determination can be made, for example, on the basis of? whether or not the transmission wave from the ultrasound transceiver unit 112a is present, and whether or not the transmission wave from the ultrasound transceiver unit 111a is present. Thus, one pair of ultra-g audio transceiver units can provide two criteria for determination.

5 The combination of reflection waveform and transmission wave 00 35 determination together yields four results for the reflection point or the transmitting point in the gas phase or the liquid phase, by four assay methods 31, i.e., V 'based determination. The final determination of whether the reflection or transmitting point is in the gas phase 5 or the liquid phase is done by selecting one of the highest priority assay results, weighting the assay methods, using multiple assay results, or arranging the assay methods using a neural network such as a support vector machine.

Next, a measurement of the water level 10 using a skewed wave will be described with reference to the ultrasonic transceiver units 111a and 112b. Figures 14 are enlarged diagrams of Fig. 10 showing paths of an ultrasonic pulse transmitted from an ultrasound transceiver unit 111a. Figures 14 (a) and 14 (b) show different water levels. Several components are not shown in these figures.

The ultrasonic transceiver unit 111a transmits the ultrasonic pulse 15 131a to the water level measuring tube 140. As shown in Fig. 14 (a), when the reflection point of the ultrasonic nipples 131a on the inner wall 140a is in the gas phase, the ultrasonic pulse 131a

On the other hand, as shown in Figure 14 (b), when the reflection point of the ultrasonic pulse 131a 20 on the inner wall 140a is in the liquid phase, the ultrasonic pulse 131a passes partially through the inner wall 140a to the liquid phase and then passes through the inner wall 140b to the ultrasonic transceiver unit 112b. The inclined wave is denoted by reference numeral 131e. The water level calculation unit 123 identifies the inclined wave 131e based on the signal received from the ultrasonic transceiver unit 251b of the control unit.

Specifically, determining whether or not a transmitted wave 131 is found is the same as determining the transmission wave described above with respect to ultrasound transmissions.

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the tin-receiver units 111a and 112a. first, the noise is removed from the receive signal by frequency filtering, and the skewed wave 131e is detected based on the ultrasonic nipple modulation mode and detection time. As in the case of the transmission wave 131d, although it is possible to detect the tilted wave 131e only in one of the modulation states and the detection time, the transmitted wave 131e can be detected.

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g more reliable using modulation mode and detection time together. Then, the threshold used in the binary determination is set to the amplitude of the aal transmitted 35 slope. If the result of the binary determination indicates that a bias transmitted wave 131e is found, then it is determined that the reflection point / transmission point is in the liquid phase. On the other hand, if the result of the binary determination indicates that there is no bias transmitted wave 131e, it is determined that the reflection / transmission point is in the gas phase.

In the case of an oblique transmitted determination, the transmission points of the wave transmitted to the oblique 5 on the inner walls 140a and 140b differ from the reflection points of the reflection waves 131b and 131c described above and the transmission point 131d. In the above-described reflection wave or transmitting setup, the reflection point and transmitting point are located at the same level as the ultrasonic transceiver unit. In oblique transmitted detection, the reflection point and transmitting point are located at levels between the pair of ultrasonic transceiver units used for the determination. Since determining whether the relevant point is in the gas phase or in the liquid phase is done by determining the presence or absence of a skewed wave, surface conditions have less influence on determining whether the relevant point is in the gas phase or in the liquid phase.

As described above, by using a bias transmitted wave, the determination can be made at a level halfway between the ultrasonic transceiver units. In other words, the determination can be made at a different level than the level of the ultrasonic transceiver unit. In the embodiment described above, ultrasonic transceiver units 111a and 112b are used. However, the determination can be made using, for example, another pair of ultrasonic transceiver units at other levels, such as a pair of ultrasonic transceiver units 111a and 112c. This setting can be made at different levels by varying the combination of ultrasonic transceiver units. With three pairs of ultrasound transceiver units as shown in Figure 10, determination can be made using 12 obliquely transmitted waves, since six combinations of 5 are possible, and determination can be made bidirectionally for each

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^ for bination.

T As described above, the liquid level measuring system 00 30 of this embodiment measures the water level by determining whether the water level measuring tubes are | The core is in the gas phase or the liquid phase, based on the reflection waves from the inner walls of the ultrasonic pulse water level measuring tube. Thus, the liquid level measuring system g can reliably measure the water level without being affected by changes in the surface conditions of the liquid tank wall.

The water level is measured by determining whether the transmitting wave from one pair of opposed ultrasonic transceiver units passes through the gas phase or the liquid phase. Thus, the liquid level measuring system can reliably measure the water level without being influenced by changes in the surface conditions of the liquid tank wall.

In the biased wave determination, the determination 5 can be made at a different level than the level of the ultrasonic transceiver units, and thus the water level can be measured more reliably.

In oblique wave detection, the number of assay results may be obtained depending on combinations of ultrasonic transceiver units, and the water level can be measured more reliably.

10 In reflection wave determinations, the transmitting wave and the oblique wave can be used together, and the water level can be measured more reliably by making such a redundant or multiplexed determination. In addition, if redundant or multiplexed detection is used, measurement of the water level is still possible even if some of the ultrasonic transceiver units are damaged or their sensitivity is reduced.

Furthermore, since the ultrasonic pulse transmitted from each ultrasonic transceiver unit is independently modulated, it is possible to determine which ultrasound transceiver unit has transmitted the received reflection wave, transmitting wave or transmitted oblique wave. This enables accurate water level measurement 20 by installing ultrasonic transceiver units close to each other, water level measurement using a large number of ultrasonic transceiver units, and reliable water level measurement using a transmitting or oblique wave.

Further, since the ultrasonic transceiver units, the modulation unit, and the water level calculator can be mounted outside the reactor vessel, such as the main cockpit or outside the controlled area, water level measurement can be made without worrying about the failure of these components.

5 In the embodiment described above, three pairs of ultrasonic transducers are used.

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^ hetin receiver units. As described above, the number of ultrasonic transceiver units and the mounting distance are not limited to any value. Further, if the 00 30 ultrasonic transceiver unit is movable vertically, or if the water level measuring tube can be scanned by an ultrasonic transceiver unit, the water level can be measured with a smaller amount (e.g. one) of ultrasonic transceiver units.

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g hetin receiver units. If the determination is made several times by scanning the water level measuring tube 140 axially with one ultrasonic transceiver unit, the water level can be accurately measured with even one ultrasonic transceiver unit. Scanning with the ultrasonic transceiver unit 34 can be done by using a robot arm to separate the ultrasonic transceiver unit from the water level measuring tube 140, move it vertically and then bring it into contact with the tube 140, or by using a ball screw or the like .

Alternatively, the ultrasonic transceiver unit attached to the water level measuring tube 140 and the axially movable ultrasonic transceiver unit of the water level measuring tube 140 may be used.

(Fifth Embodiment) A fifth embodiment of the invention will now be described with reference to the Figures. The same parts as in the fourth embodiment are denoted by the same reference numerals, and repeated descriptions are omitted. Figure 15 is an enlarged view of a water level measuring tube with a fluid level measuring system according to this embodiment.

In this embodiment, the ultrasonic transceiver units 111a, 111b and 111c are attached to a water level measuring tube. The reflector plate 124 is attached to the inner wall 140b of the water level measuring tube 140. Reflector plate 124 is a unit that reflects ultrasonic pulses from ultrasonic transceiver units 111a, 111b, and 111c, and has a higher ultrasonic reflectance than inner tube wall 140b. The ultrasonic transceiver unit 113 is attached to the lower portion of the water level measuring tube 140. The ultrasonic transceiver unit 113 is coupled to a second water control unit 125 separate from the control unit 121. The second control unit 125 is connected to a second water level calculating unit 126. In addition, the acoustic rate calculating unit 127 is coupled to the control unit 121 and the second control unit 125.

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Like the water level measuring tube 140, the reflector plate 124 is made of stainless steel, nickel-based alloy, low-alloy steel, carbon steel or the like. The reflector plate 124 has a planar shape such that the flat surface is aligned parallel to the axis of the water level measuring tube 140 and 30 so that the reflector plate 124 reflects the ultrasonic pulse

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mucoid. The reflector plate 124 is welded to the inner wall 140b. The plate may have a conical or pyramidal depression formed. Figure 16 (a) is a front view of the reflector plate 124, and Figure 16 (b) is a cross-sectional view taken along line A-A of Figure 16 (a). Preferably, the conical depression 24a has a bottom surface area 35 near the ultrasonic transceiver units. 111a, 111b and 111c the transmission / reception surface area. Alternatively, the reflector assembly 35 may be formed by polishing the inner wall of the water level measuring tube 140, processing the inner wall into a flat surface, or forming a cone or pyramidal depression directly on the inner wall.

In the following description of this embodiment, it is assumed that the hi-5 baffle plate 124 is an elongated flat plate that extends in the axial direction of the water level measuring tube 140.

Like the ultrasonic transceiver unit 111a, 111b and 111c, the ultrasonic transceiver unit 113 consists of an oscillator made of a heat-resistant and radiation-resistant material, such as lithium niobate, and is fixed to the lower end of a water level measuring tube 140 by a metal or liquid. The frequency of the ultrasonic pulse is set in the range from several hundred kHz to several hundred MHz, so that the ultrasonic pulse can pass through the water level measuring tube 140 and the liquid phase.

Like the control unit 121, the second control unit 125 has a magnifier-15 hair-generating circuit which generates an electrical signal to command the ultrasonic transceiver unit 113 to produce an ultrasonic pulse, and a voltage amplification circuit which detects the ultrasonic pulse received by the ultrasonic transceiver unit 113.

Like the control unit 121 or the like, the second control unit 125, the second water level calculating unit 126 and the acoustic velocity calculating unit 127 are mounted outside the reactor container, such as outside the nuclear power plant main control room or controlled area, and are connected to the ultrasonic transceiver unit 113 or equivalent. through a permeable pipe.

The second water level calculating unit 126 detects a reflected wave from the liquid surface in the water 25 level measuring tube 140 from the electrical signals of the second control unit 125. Specifically, the second water level calculating unit 126 determines the water level in the measuring tube 140 with the ultrasonic transceiver

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a wave transmitted by unit 113 reflected from the liquid surface and received by the ultrasonic transceiver unit 113.

00 30 As described above in connection with the fourth embodiment of the reflection wave Determining the Ion and the transmitting wave, the reflection wave is determined by a binary determination using a threshold set for the amplitude of the electrical signals. If the detected electrical signal contains a significant amount of noise, preprocessing such as noise reduction or waveform discrimination, using an analog or digital filtering circuit or frequency filtering software, a reflection wave from the liquid surface is detected.

36

The acoustic velocity calculating unit 127 detects a reflection wave emitted from an internal wall 140a of a water level measuring tube 140 and a reflection plate 124 from a reflection plate 124 mounted on an inner wall 140b, as received by a voltage amplifier circuit 111, i.e., ultrasonic As in the fourth embodiment, the determination is made by a binary determination using a threshold set for the amplitude of the electrical signals.

Further, the acoustic velocity calculating unit 127 determines the detection time 10 difference A At between the reflection wave from the inner wall 140a and the reflection wave from the reflector plate 124 and determines the ultrasonic pulse from the detection time difference A At and the known distance according to the inner wall 140a and reflector plate 124.

v = 2 * d / At (5) 15 The reflection wave experiences multiple reflections of the wall of the water level measuring tube 140, the liquid phase of the water level measuring tube 140 and the like. Thus, the presence or absence of reflection waves or the acoustic velocity of the ultrasonic pulse can be determined using a reflection wave experienced by multiple reflections.

The operation of the liquid level measurement system of this embodiment will now be described. As in the fourth embodiment, whether it is in the gas phase or in the liquid phase of the water level measuring tube 140, it is determined using the reflection waves received by the ultrasonic transceiver units 111a, 111b and 111c inside the water level measuring tube. Since the reflector plate 124 is used in this embodiment, the receive signal has a greater amplitude and a higher S / N ratio than the reflection wave received from the inner wall 140b. Thus, the water level calculating unit 124 can more easily determine the reflection wave t1 Ion 131c. In addition, determining whether the relevant point is in the gas phase or liquid phase by using the amplitude or amplitude ratio V of the reflection waveform 131c can also be made more reliably, g 30 The acoustic velocity calculator 127 determines the ultrasonic wave

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acoustic velocity v according to formula (5) described above. Because of the ultrasonic wave

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§ the relationship between the acoustic velocity v and the temperature of the liquid phase is known, the temperature of the liquid phase can be determined. Thus, it can be checked whether the ultrasonic transceiver units 111a, 111b, and 111c and other devices are used at their intended operating temperatures.

37

The reflection wave from the ultrasonic transceiver unit 113 transmitted by the ultrasonic transceiver unit 113 is received by the ultrasonic transceiver unit 113. The reflection wave from the liquid interface is detected by the second control unit 125, and the result of the detection is communicated with the second water level calculating unit 126 at ultrasound. From the time difference between the ultrasonic transceiver unit 113 transmitting the ultrasonic pulse and the ultrasonic transceiver unit 113 receiving the reflection wave from the liquid surface, the ultrasound propagation time t1 in the liquid phase is determined. The second water level calculating unit 126 calculates the water level I according to the following formula (6).

10 l = ti * v / 2 (6) In this way, the water level can be continuously measured by determining the acoustic velocity during the water level measurement from the lateral direction of the water level measuring tube 140 and using the determined acoustic velocity v and the receiving signal of the ultrasonic transceiver unit 113 .

As described above, the liquid level measuring system of this embodiment has a reflector plate 124 of high reflectivity in the inner wall 140b, and therefore the reflection wave has a larger waveform amplitude and a higher S / N ratio. Therefore, determining whether the relevant point is in the gas phase or in the liquid phase by using a reflection wave can be more easily done and the measurement can be made more reliably.

Further, the temperature of the liquid phase can be determined using a reflection wave from the inner wall 140a and a reflection wave from the reflector plate 124. Thus, it can be checked whether the ultrasonic transceiver units 111a, 2511b and 111c and other devices are used at their intended operating temperatures, and the water level measurement can be made more reliably. In addition, the water level measurement can be continuously performed using the ultrasonic pulse transmitted from the lower a reflection wave propagating through the liquid phase and reflected from the surface of the liquid. In addition, the water level can be measured without being influenced by the surface conditions of the liquid tank wall.

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road changes, and the measurement can be made more reliably.

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The sixth embodiment of the invention will now be described with reference to the figures. The same parts as in the fourth embodiment are denoted by the same reference numerals, and repetitive descriptions are omitted. Fig. 17 is an enlarged view 38 of a water level measuring tube in a liquid level measuring system according to this embodiment. In this embodiment, the delay unit 128 replaces the modulation unit 122. Like the control unit 121 and the like, the delay unit 128 is mounted outside the reactor container such as the main cab or outside the controlled area.

The delay unit 128 is a delay circuit coupled to the high voltage generating circuit of the control unit 121 and delays the electrical signal received from the control unit 121 by a preset time and supplies the delayed signal to each ultrasonic transceiver unit.

The delay unit 128 sets the delay time for the hand signal transmitted from the control unit 121 to each ultrasonic transceiver unit so that opposite pairs of ultrasonic transceiver units can transmit an ultrasonic pulse at certain time intervals. In the example shown in FIG. .

When the timing of the transmission of the ultrasonic pulse is controlled in this way, no other pair of ultrasonic transceiver units transmits an ultrasonic pulse, for example when the ultrasonic transceiver units 111a and 112a are in use. Thus, it is possible to reliably determine which ultrasonic transceiver unit has transmitted that ultrasonic pulse without the need to modulate the ultrasonic pulse of each ultrasonic transceiver unit individually, thereby reliably measuring the water level. In this case, the ultrasound transceiver units other than the ultrasound transceiver units 111a and 112a also receive an ultrasonic pulse transmitting or obliquely transmitted wave, and thus assays using reflection wave, transmitting wave and oblique transmitted wave can be used.

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This works together, as in the case of the modulation unit 122.

As described above, several assay results are obtained for each relay level with respect to whether the level is in the gas phase or in the liquid phase.

The water level can be reliably measured by determining whether the relevant point c / j is in the gas phase or in the liquid phase, by selecting the

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g the highest priority by weighting the results, using multiple

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or arranging the assay results on a neural network such as a support vector machine.

39

As described above, the liquid level measurement system of this embodiment sets a delay time for each pair of opposing ultrasonic transceiver units so that a pair of opposing ultrasonic transceiver units transmit an ultrasonic pulse in time slots. Thus, erroneous detection due to misidentification of the ultrasonic pulses transmitted from the various ultrasound transceiver units can be avoided, and the water level can be measured more reliably without the need to modulate the ultrasound pulse transmitted from each ultrasonic transceiver unit individually.

In addition, the reflection wave, transmitting wave and oblique wave detection methods can be used together, and thus the water level can be measured more reliably.

Furthermore, since the ultrasonic transceiver units, the delay unit and the water level calculator are mounted outside the reactor container, such as the main cockpit or outside the controlled area, and separated from the water level measuring tube, the water level can be measured more reliably even under high temperature and high radiation conditions.

(Seventh embodiment)

A seventh embodiment of the invention will now be described with reference to the figures. The same portions as in the fourth embodiment are denoted by the same five to twenty digits, and repeated descriptions are omitted. Fig. 18 is an enlarged cross-sectional view of a water level measuring tube in a fluid level measuring system of this embodiment taken perpendicular to its axis. In this embodiment, the ultrasonic transceiver units 111a, 112a, 114a and 115a are attached to the water level measuring tube 140 and are electrically connected to the control unit 121. The display of the other parts is ignored.

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In this embodiment, a plurality of ultrasonic transceiver units are attached to a water level measuring tube 140 along its circumference. Determining whether V is the relevant point in the gas phase or the liquid phase is done using a c0 reflection wave or a transmitting wave in the same manner as in the fourth £ 30 embodiment described above.

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Because the fluid level measuring system of this embodiment has a plurality of ultrasonic transceiver units along the circumference of the water level tube, several determinations are made at one level as to whether

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c'J, i.e. in the gas phase or in the liquid phase, and thus the water level can be measured more reliably without effecting changes in the surface conditions of the liquid tank.

This embodiment has four ultrasonic transceiver units 111a, 112a, 114a and 115a. However, there may be only three ultrasonic transceiver units 111a, 112a and 115a, and the reflector plate 124 described in the fifth embodiment may be affixed to the inner wall 5 of the water level measuring tube 140 at a position corresponding to the ultrasonic transceiver units 114a. Of course, there is no limit to the number of ultrasonic transceiver units arranged along the circumference of the water level measuring tube.

Although embodiments of the present invention have been described with reference to the drawings, the features of the above-described embodiments may be arbitrarily combined with anyone. For example, even though the sixth embodiment uses a delay unit 128 instead of a modulation unit 122, the delay unit 128 and the modulation unit 122 may be used together. In addition, the ultrasonic transceiver unit may detect a reflection wave even if it has not been paired, and thus some or all of the ultrasonic transceiver units may not be paired. Further, although the measurement of the water level of the reactor pressure vessel is described in the above embodiments, the liquid level measurement system of the invention is not limited to the reactor pressure vessel.

(Eighth embodiment)

Fig. 19 is a diagram illustrating a reactor water level measurement system according to an eighth embodiment of the invention.

The reactor water level measuring system 300 according to this embodiment has a water level measuring tube 301 mounted outside the reactor pressure vessel 201, an ultrasonic transceiver unit 306, a first ultrasonic converter 307, a second ultrasonic converter 308, signal 25 units and water level unit 30.

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^ The water level measuring tube 301 communicates with the reactor pressure vessel 201 inside the ^ Susta at two locations at different levels. The water level measuring tube 301 has an O V substantially U-shaped cross section and has a reactor c0 water pulling member 302 for drawing reactor water from inside the reactor pressure vessel 201, | 30 steam drive unit 303 for drawing steam from inside the reactor pressure vessel 201, and a body member 304 for interconnecting reactor water drive member 302 and steam drive member 303. The water level measuring tube 301 is covered with thermal insulation 212 surrounding the reactor pressure vessel 201.

o ™ Reactor Water Trap 301 for Water Level Tube 301 and Steam 35 Trap 303 is inclined upward toward the outer wall of the reactor pressure vessel 201. Alternatively, portions 302 and 303 may extend horizontally. The body portion of the water level measuring tube 411 extends vertically along the wall of the reactor pressure vessel 201. The water level measuring tube 301 has a protrusion portion 305 that extends vertically downwardly over the coupling point of the reactor water supply portion 302 to the reactor pressure vessel 201.

The ultrasonic transmitter 306 is mounted outside the biological shield 211 surrounding the reactor pressure vessel 201 and provides a control signal to operate the first and second ultrasonic transducers 307 and 308 continuously or periodically at each preset water level measurement interval.

The first ultrasonic transducer 307 is mounted against the bottom surface of the projection 305 against the surface L 'of water in the water level measuring tube 301 and is held by a thermal insulator 212 surrounding the reactor pressure vessel 201 as a fitting unit.

The first ultrasonic transducer 307 is coupled to the ultrasonic transmitter 306 by a signal cable 309 and includes a piezoelectric element which transmits 15 ultrasonic waves towards the water surface L 'of the water level measuring tube 301 in response to a control signal from the ultrasonic transmitter 306. Further, the first ultrasonic transducer 307 receives various reflection waves from the water surface L ', steam above the water surface, or the inner wall or other portions of the water level measuring tube 301 and produces a reflection wave signal.

The signal cable 309 interconnecting the ultrasonic transmitter 306 outside the biological shield 211 and the first ultrasonic transducer 307 inside the biological shield 211 passes through a hole (piercing) formed in the biological shield 211 surrounding the reactor pressure vessel 201.

A second ultrasonic transducer 308 is mounted on the outer surface of the projection 305 of the water level measuring tube 25 301 and is held by the thermal insulation 212 surrounding the reactor pressure vessel 201.

A second ultrasonic transducer 308 is coupled to the ultrasonic transducer 306

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^ signal cable 309, and includes a piezoelectric element which transmits an ultrasonic wave at a frequency from tens of kHz to several hundreds of kHz 00 30 in the radial direction (toward the facing inner wall) of the projection 305 | na to the control signal from the ultrasonic transmitter 306. In addition, the second ultrasonic transducer 308 receives the reflection wave from the inside of the water level measuring tube 301, from the inside wall or the like, and outputs a reflection wave signal.

The inside wall of the projection 305 receiving the ultrasonic wave from the second 00 35 ultrasonic transducer 308 has an ultrasonic reflecting surface 310 which reflects the ultrasonic wave in a direction parallel to its input direction (e.g., a conical surface projecting outwardly in the body portion 304).

The water level counting unit 311 is mounted outside the biological shield 211 surrounding the reactor pressure vessel 201, such as an ultrasonic transmitter 306.

Based on the reflection wave signals generated by the first and second ultrasonic transducers 307 and 308, the water level calculating unit 311 calculates the water level in the water measuring tube (called the intracellular water level) from time to time of ultrasound transmission level of in-pipe water level.

Next, the water level calculation process performed by the water level calculating unit 311 will be described.

First, the reflection of the various reflection components in the reflection waveform produced by the first ultrasonic transducer 307 (such as the reflection wave from the water surface 151, the reflection wave from the water level measuring tube 301, and reflection wave component).

Fig. 20 is a graph showing a waveform of a measured wave X, an example of a reflection wave signal produced by a first ultrasonic converter 307. The X axis represents time, and the Y axis indicates the amplitude of the received ultrasound wave, which indicates the intensity of the ultrasound wave. Time can be converted to distance using acoustic speed. Thus, in the following description 25, it is assumed that the X axis represents the distance.

As shown in Figure 20, the measured wave X supplied to the water level calculating unit 311 includes a plurality of overlapping reflections.

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^ waveguide components. In the observed waveform of the measured wave X, a reflection wave from the bottom of the water level measuring tube 301 forms a first peak 00 00, and a reflection wave from the water surface U forms a second peak 1 (the relevant reflection wave component Y). As the ultrasonic wave attenuates until it reaches the first ultrasonic transducer 307 after reflecting water o g from surface L ', the peak of the relevant reflection wave component Y is low. So the noise

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Noise with peaks equal to 00 35 or greater than the peak of the relevant reflection wave component is detected in the female environment so that the relevant reflection wave component 43 of the reflection wave from the water level U of the water measuring tube 301 is difficult to determine, e.g. In addition, the reflection wave from the water level L 'is likely to scatter and attenuate due to disturbances in the water surface U. As a result, the S / N ratio decreases and thus the reflection wave from the water surface L 'is difficult to distinguish from the other reflection wave components.

Even in a noisy environment, however, the relevant reflection wave component Y can be readily determined by the "reference wave" of the relevant reflection wave component prepared before the water level measurement and the measured wave obtained from the water level measurement. pattern components).

The following describes the pattern matching procedure.

The water level calculator pre-stores the reference wave Z for pattern matching. The reference wave Z (see Figure 20) has a reflected ultrasonic waveform from the surface L 'of water 15, which is received by the first ultrasonic transducer under conditions suitable for water level measurement. The reference z to Z is determined analytically or actually by measuring the waveform of the signal using the correct machine or model under conditions where the water surface L 'is not significantly disturbed.

Then, the correlation value Φ (ζ) between the measured wave X and the reference wave Z is determined by moving the reference wave Z along the distance axis of the measured wave X. The correlation value Φ (ζ) is determined by the following formula.

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o 25 f (z): measured wave X

ό g (z): Reference wave Z

z: distance 00 As shown in Fig. 20, when shifting the reference wave (changing the distance z), the correlation between the measured wave X and the reference wave Z is decreased by 30 repeatedly. The result of the correlation value Φ (ζ) is shown in Fig. 21. Fig. 21 is a schematic graph of S showing the measured wave X and the reference wave Z

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5 correlations calculated along the distance axis of the measured wave X. Assuming that the remote

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the reason why the reflection wave component Y in the measured wave X is relevant

44 is received, denoted by zmax, the correlation value Φ (ζ) represents a remarkably sharp peak at zmax, and is low at other distances.

The distance zmax at which the correlation value Φ (ζ) peaks, is determined as the water level in the water level measuring tube 301 (as the intra-tube water level), and the fitting procedure of FIG. 5 is completed.

The operation of the second ultrasonic converter 308 will now be described. As described above, the second ultrasonic transducer 308 transmits an ultrasound wave to the ultrasound reflecting surface 310 and receives a reflection wave from the ultrasound reflecting surface 310. The distance between the second ultrasonic transducer and the ultrasonic reflecting surface 310 10 is known from the specifications of the water level measuring tube 301. Thus, the distance between the second ultrasonic transducer 308 and the ultrasound reflecting surface 310 and the time when the second ultrasonic transducer 308 transmits an ultrasound wave to receive the ultrasound reflected from the ultrasound reflecting surface 310 can determine the acoustic velocity in the water improves by performing a distance correction of the reception signal produced by the first ultrasonic transducer 307 using a specified acoustic speed.

The advantage of the projection 305 will now be described. For a period of time after the ultrasonic transducer 307 transmits the ultrasonic wave, the ultrasonic transducer 20 307 receives reflection waves from the support portion used to attach the ultrasound transducer, reflection waves from the inner and outer surfaces of the water level measuring tube 301, and other reflection waves. Thus, although the ultrasonic transducer 307 receives a reflection wave from the water surface L 'during this time period, it is difficult to determine the correct reflection wave component Y. Thus, with the water level low 25 and the distance between the ultrasonic transducer 307 and the water surface L' small To solve this problem, the water-measuring tube 301 has a projection portion 305 that provides a sufficient distance from the ultrasound

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between the sound transducer 307 and the water surface L 'to prevent the reception of a reflection wave v from the water surface L' during the period described above. The length 00 30 of the projection 305 is such that it provides sufficient reflection time to prevent fire from the water surface L '. reception of a van reflection wave over the period described above.

The reactor water level measuring system 300 according to this embodiment has the following advantages.

° 1. Since the water level measuring tube is covered with thermal insulation 212 of the reactor pressure vessel 201 00 35, the internal environment of the water level measuring tube is close to the internal environment of the reactor pressure vessel. Thus, there is no need to correct the temperature or density of the reactor water level measuring tube 301 to the value of reactor water in the reactor pressure vessel 201. In other words, the water level defined by the ultrasonic sensing unit and the water level calculating unit 311 in the water level measuring tube 301 can be maintained in the water level reactor pressure vessel 201 without compromising the accuracy of the water level measurement.

Thus, the reactor water level measurement system 300 can measure the reactor water level by a different method than the differential pressure method, and can accurately measure the water level with a simple system configuration.

2. The water level calculating unit 311 determines the previously prepared reference wave Z of the measured wave X 10, which represents the relevant reflection wave component Y coming from the water surface L 'in the water level measuring tube 301, and . The pattern fitting is made on the basis of the correlation value Φ (ζ) between the relevant reflection wave component Y and the reference wave Z 15. Thus, even in a noisy environment where the water surface U is disturbed in the water level measuring tube 301, or when other reflection wave components are present, the water level can be very accurately measured.

3. The projection portion 305 eliminates the effect of noise immediately after the ultrasound transducer 307 transmits an ultrasonic wave. In this way, the relevant reflection wave component Y can be more easily distinguished from noise (other reflection wave components).

4. The ultrasonic transceiver units are arranged to transmit an ultrasonic wave from the water side of the reactor to the steam side in the water level measuring tube 301.

Thus, the diffused reflection of the ultrasonic wave from the vapor can be minimized, the re-levant reflection wave component Y, which is likely to be attenuated by the water-5 nan U interference and multiple reflections from different structural surfaces

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^ therefore, can be expressed and the water level measured.

T 5. Acoustic velocity in reactor water in water level measuring tube 301 00 30 can be accurately determined using another ultrasonic transducer 308. Using | The acoustic speed of the water level can be accurately calculated. 6. The ultrasonic reflecting surface 310 reflects the second ultrasonic transducer

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g 308 in the direction of the ultrasound wave received parallel to the ultrasound? wave hit direction. Thus, the second ultrasonic transducer 308 receives a strong reflection wave from the ultrasonic reflecting surface 310. Thus, the acoustic velocity calculation using the second ultrasonic transducer 308 is improved.

7. At least that portion of the water level tube intended to draw steam from the reactor pressure vessel 201 extends horizontally or inclined upwardly toward the reactor pressure vessel 201. Thus, the accumulation of non-condensable gas produced by radiolysis such as hydrogen and oxygen can be prevented 5 the integrity of the end of the measuring tube used to draw or collect steam may be maintained for a long time.

(Ninth embodiment)

Fig. 22 is a diagram of a water level measuring system according to a ninth embodiment of the invention. The reactor water level measuring system 10 according to this embodiment differs from the reactor water level measuring system 300 according to the eighth embodiment in that the water level measuring tube 301 has been modified. The same parts as in the eighth embodiment are denoted by the same reference numerals and their description is omitted. Modified or new parts shall be identified by reference numbers accompanied by an "A".

As shown in Figure 22, the water level measuring tube 301A has a plurality of reactor water-conducting portions 302A.

Reactor Water Traction Parts 302A are reactor water traction units formed at two or more locations at different levels above the reactor water traction portion 302 and function in substantially the same manner as the reactor water traction portion 302. Thus, the reactor water traction portions 302A provide at least two portions that communicate reactor pressure vessel 201 in the reactor pressure vessel 201 when the reactor is operating normally.

The reactor water level measuring system has the following advantages in addition to the advantages of the eighth embodiment (1) to (7).

25 8. Because the water level measuring tube 301A has several reactor water draws,

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The portions 302A, which communicate with the reactor pressure vessel 201 at different levels in the reactor pressure vessel 201, transfer the reactor water to the water level measuring tube.

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v sa 301A is facilitated, and a more efficient leveling of the reactor water in the water level measuring tube 301A occurs. Thus, the reactor water circulation in the reactor pressure vessel 201 | 30 and the water level measuring tube 301A are facilitated. As a result, the reactor water environment in the water level measuring tube 301A is close to the reactor water environment p in the reactor pressure vessel 201. Thus, the reactor water level can be measured more accurately without the need for density or temperature correction.

o w Reactor water for recycling through the water level measuring tube 301A does not require special conveying equipment and has the advantage (8) of a simple system configuration.

47 (Tenth embodiment)

Fig. 23 is a diagram illustrating a reactor water level measurement system according to a tenth embodiment of the invention. The reactor water level measuring system according to this embodiment differs from the reactor water level measuring system 300 according to the eighth embodiment in that the water level measuring tube 301 and the ultrasonic transceiver units have been modified. The same parts as in the eighth embodiment are denoted by the same reference numerals and their description is omitted. Modified or new parts shall be identified by reference numbers enclosed in "B".

As shown in Figure 23, the reactor water level measuring system 300B of this embodiment has a water level measuring tube 301B, a first ultrasonic transducer 307 and a third ultrasonic transducer 307B.

The water level measuring tube 301B has a tube 351B (hot branch) corresponding to the water level measuring tube 301 in an eighth embodiment, and a tube 15 352B (cold branch) connected to the reactor water drawing section 302 and the steam drawing section 303 to the reactor pressure vessel 201. The tube 352B has a projection portion 305B projecting downwardly like the tube 351B. A third ultrasonic transducer 307B is attached to the bottom of tube 352B. The water surfaces in pipes 351B and 352B are designated L 'and L', respectively.

The following describes a reactor water level measurement system 300B

activity.

The functions of the tube 351B and the first ultrasonic transducer 307 in measuring the water level are the same as in the eighth embodiment. Although not shown, the functions and advantages of the second ultrasonic transducer 308 and the ultrasound reflecting surface 25 310 are also the same as those of the eighth embodiment cvj δ Like the ultrasonic transducer 307, the third ultrasonic converter 307B is connected an element which transmits at an ultrasonic wave frequency from several tens of 00 to several hundreds of kHz towards the water surface L 'in tube 352B in response to a control signal from the ultrasonic transmitter 306, and produces a reflection waveform signal. As in tube 351B, the acoustic velocity in tube 352B can be determined using an ultrasonic reflective surface 310B formed on the inner surface of the projection 305B and a fourth ultrasonic transducer 308B mounted

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35 ten ultrasonic reflecting surfaces 310B.

48

Because tube 352B is not covered with thermal insulation 212, the reactor water in tube 352B has a lower temperature than the reactor water in the reactor pressure vessel 201.

For example, if an event causes a rapid pressure drop in the reactor pressure vessel 201, flash boiling of the reactor water may occur. When overheating occurs, the reactor water is in two phases or is a mixture of gas and liquid. In this case, over boiling also occurs in tube 351B (hot branch), which is designed to be at the same temperature conditions as reactor pressure vessel 201, and the water level cannot be much reduced by first ultrasonic transducer 307. Because tube 352B temperature is lower than reactor pressure vessel 201 , even in this case, however, the over boiling and the resulting gas / liquid biphasic phase does not occur in tube 352B. Even in this case, when the reactor pressure vessel 201 or tube 351B is overheated, the water level in tube 352B can still be measured.

For example, the water level can be measured with the tube and the first ultrasonic transducer 307 in normal operation, and with the tube 352B and the third ultrasonic transducer 307B when the reactor pressure vessel 201 is overheated. This way the water level can be measured more reliably.

As described above, the reactor water level measurement system 300B

has the following advantages in addition to those of the eighth embodiment (1) to (7).

(9) The reactor water level measuring system 300B has a pipe 352B which is not covered by thermal insulation 212, and thus the water level can be measured, for example, when reactor pressure vessel is overheated.

In this embodiment described above, measuring tube 301B has integral tube 351B (hot branch) and tube 352B (cold branch). However, the hot branch and the cold branch may be attached to the reactor pressure vessel 201

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^ separate pipes.

Generally speaking, the reactor pressure vessel 201 part of the bottom of the steam-water separator 00 30 206 to the main steam pipe 210 is called the narrow region, and part of the reaction | rin core 202 to main steam tube 210 is called a wide area. For example, if the hot branch covered by the thermal insulation 212 can extend over a narrow area, and if the cold branch exposed on the insulation 212 extends over a wide area, can? meets the requirements for measuring reactor water level.

CVJ

49 (Eleventh embodiment)

Figure 24 is a diagram illustrating a reactor water level measurement system according to an eleventh embodiment of the invention. The reactor water level measuring system according to this embodiment is the reactor water level measuring system 300 according to the eighth embodiment with one additional part. The same parts as in the eighth embodiment are denoted by the same reference numerals and their description is omitted. Modified or new parts are identified by reference numbers enclosed in "C".

As shown in Figure 24, the reactor water level measurement system 300C of this embodiment has a cooler 312C.

The cooler 312C is designed to remove heat from the reactor water in the water level measuring tube 301. For example, purifying water to prevent reactor water from entering the control rod control mechanism 209 is used as circulating water, and the circulating water is supplied to the water level measuring tube 301.

The reactor water level measuring system 300C has the following advantages in addition to the advantages of the eighth embodiment (1) to (7).

(10) Since the water level measuring system 300C has a condenser 312 which cools the reactor water in the water level measuring tube 301, even if the reactor water in the reactor pressure vessel 201 is in gas / liquid biphasic state due to overheating 20, the reactor water in Thus, even if the reactor water is in the gas / liquid two phase state due to over boiling or the like, the level of reactor water in the reactor pressure vessel 201 can be measured.

Although cooler 312 uses water in the above description, other liquids or gases may be used for cooling.

Although Figure 24 does not show thermal insulation 212, this embodiment can be used regardless of whether the water level measuring tube 301 is covered by thermal insulation 212. In addition, the condenser may be configured not to function in normal operation, but to operate to determine that a deviation occurs. 00 30 overheating and water level cannot be measured with an ultrasonic transducer 307.

CC

CL

Fig. 25 is a diagram illustrating a reactor water level measurement system according to a twelfth embodiment of the invention. The reactor water level measuring system according to this embodiment is a modification of the reactor water level measuring system 50 300 according to the eighth embodiment, in which the water level measuring tube 301 is modified. The same parts as in the eighth embodiment are denoted by the same reference numerals and their description is omitted. Modified or new parts shall be identified by reference numbers accompanied by an 'D'.

As shown in Figure 25, the reactor water level measurement system 300D of this embodiment has a plurality of barbs 313D in the water level measuring tube 301D. The barb 313D is arranged on the outer surface of the water measuring tube 301D to substantially increase the outer surface of the water measuring tube 301D.

The reactor water level measuring system 300D has the following advantages in addition to those of the eighth embodiment (1) to (7).

(11) The body portion 304 of the water level measuring tube 301D has a significantly increased outer surface area compared to the inner surface due to the barb 313D, and thus the reactor water in the water measuring tube 301D can be effectively cooled despite the system being air-cooled. Thus, even if the reactor water in the reactor pressure vessel 201 is in the gas / liquid biphasic state due to over boiling, the reactor water in the water level measuring tube 301D is still in one phase and the water surface remains flat. Thus, the reactor water level in the reactor pressure vessel 201 can be accurately determined without the cold branch (Fig. 23) or the cooler 312 (Fig. 24) even when the reactor pressure vessel 201 in the gas / liquid biphasic state due to over boiling or the like.

Although the above described eighth line of the invention reactor water level measurement systems according to the twelfth embodiment are described, the present invention is not limited to certain configurations according to these embodiments, and various modifications or additions may be made without departing from the scope of the invention.

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5 For example, the number of water level measuring tubes or each water level

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The number of reactor water passages in the measuring tube can be suitably determined so that they function effectively in each embodiment.

Although these reactor water according to the above described embodiments | Level measurement systems are used in BWR (ABWR), they can be equally well used in a PWR secondary cooling system device (feed g hot water heater). The reactor water level measuring systems of the invention are used in conjunction with or as an alternative to the differential pressure type reactor water measuring system 0035.

51

In summary, the present invention provides a reactor water measuring system that measures the level of reactor water in a reactor pressure vessel, comprising essentially: a water level measuring tube immersed in a thermal insulator surrounding the reactor pressure vessel and communicating with the reactor pressure vessel core 5 at at least two locations; an ultrasonic transceiver unit, which transmits an ultrasonic wave to the surface of the water in a water level measuring tube, receives a reflection wave from the surface of the water, and produces an ultrasonic wave signal; and a water level calculating unit, which calculates the water level in the water level measuring tube in the water using the reflection time between ultrasonic transmission and the reflection wave and the acoustic velocity of the ultrasonic wave in the ultrasonic transceiver water level, and various basic modifications and additions can be made to this basic configuration.

Although several embodiments of the invention have been described, water level measuring systems according to various combinations of embodiments are also possible. For example, the ultrasonic transceiver unit 111a described in the fifth embodiment and the second ultrasonic converter 308 described in the eighth embodiment may be used together.

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Claims (22)

52 A reactor water level measuring system for measuring the water level in a reactor pressure vessel (21, 100, 201), comprising: a water level measuring tube (26, 26A, 140, 301, 301B, 301D) having 5 reactor pressure vessels (21, 100, 201). a) a Driving portion communicating with a saturated vapor phase region and a Driving portion communicating with a reactor pressure vessel (21, 100, 201); gas phase side of the detection unit (40a, 43a, 41; 27A, 28A, 29A, 30A; 27B, 28B, 29B, 30B) which transmits an ultrasonic wave or the microwave from the gas phase 10 in the liquid phase the water level in the measuring tube (26, 26A, 140, 301, 301B, 301D); receiving a reflection wave from the gas liquid interface and generating a reflection wave signal; The liquid phase side of the detection unit (40b, 43b, 41; 40bB, 43bB, 41) which transmits an ultrasonic wave from the liquid phase to the gas phase the water level in the measurement pipe 15 (26, 26A, 140, 301, 301B, 301D) receives a reflection wave gas-nesteraja- surface and produce heijastusaaltosignaalin; and water-level calculation unit (31, 123, 124, 311) which calculates the reactor water level by using gas-phase side of the detection unit (40a, 43a, 41; 27A, 28A, 29A, 30A; 27B, 28B, 29B, 30B) heijastusaaltosignaalia produced and liquefied 20-phase side of the detection unit (40b, 43b, 41; 40bB, 43bB, 41) heijastusaaltosignaalia produced, characterized in that the water level in the measuring tube (26, 26A, 140, 301, 301B, 301D) is mounted outside reactor pressure vessel (21, 100, 201) , and that the reactor water level measuring system comprises a float (58, 60B) which floats in liquid phase in the water level measuring tube (26, 26A, 140, 301, 301B, 301D) and heats the ultrasonic wave or microwave. CVJ 2. according to claim 1, reactor water level in the measuring CNJ ^ system, characterized in that the gas phase side of the detection unit (40a, 43a, 41; ^ 27A, 28A, 29A, 30A; 27B, 28B, 29B, 30B) comprising: 00 a gas phase side of the ultrasonic transducer unit is positioned at the upper end of the water level 3 measuring tube (26, 26A, 140, 301, 301B, 301D), transmits an ultrasonic sound wave from the gas phase to the liquid phase in the water level measuring tube (26, 26A, 140, og 301, 301B, 301D), receives a reflection wave a gas-liquid interface and outputting a reflection wave signal; 00 ultrasonic transmitter (41) which produces an electrical signal 35 to the gas phase side of the ultrasonic transducer (40a); and 53 of the cable transfer unit (43a) that provides the transfer path for the electronic Priva-sufaasipuolen between the ultrasonic transducer (40a) and the ultrasonic transmitter (41). 3. according to claim 1 of the reactor water level measurement system, characterized in that the liquid phase side of the detection unit (40b, 43b, 41; 5 40bB, 43bB, 41) comprising: a liquid phase side of the ultrasonic transducer unit, which is located in the water level in the measuring tube (26, 26A, 140, 301, 301B, 301D) to the lower end, transmits an ultrasonic wave from the liquid phase to the gas phase in a water level measuring tube (26, 26A, 140, 301, 301B, 301D), receives a reflection wave from the gas-liquid interface and produces a reflection wave signal; an ultrasonic transmitter (41) which produces an electrical signal to the liquid phase side ultrasonic transducer (40b; 40bB); and the cable transfer unit (43b; 43bB), which provides an electrical signal transmission path, the liquid phase side ultrasonic transducer (40b; 40bB) and the ultrasonic transmitter (41) 15 route. Reactor water level measuring system according to claim 2 or 3, characterized in that the ultrasonic transmitter (41) and the water level calculation unit (31, 123, 124, 311) are mounted outside the biological protective wall (37). Reactor water level measuring system according to claim 2 or 3, characterized in that the water level calculation unit (31, 123, 124, 311) performs a density correction in the water and water level measuring tube (26, 26A) in the reactor pressure vessel (21, 100, 201). , 140, 301, 301B, 301D). 6. claimed in claim reactor water level mittausjärjes-25 system according to claim 1, characterized in that the gas phase side of the detection unit (40a, 43a, 41; 27A, 28A, 29A, 30A; 27B, 28B, 29B, 30B) comprising: o a microwave source (27A; 27B) , which produces a microwave; A microwave detection unit (30A, 30B) which detects a reflection microwave and outputs a reflection wave signal; An antenna unit (29A; 29B) transmitting a microwave from gas phase 1 to liquid phase in a water level measuring tube (26, 26A, 140, 301, 301B, 301D) and receiving a reflection wave from the gas-liquid interface; and o g a cable transfer unit (28A; 28B) providing a path for the microwave and? a reflection microwave between the microwave source (27A; 27B) and the antenna unit (29A; ™ 35 29B). 54 Reactor water level measurement system according to claim 6, characterized in that the microwave source (27A; 27B), the microwave detection unit (30A, 30B) and the water level calculation unit (31, 123, 124, 311) are mounted outside the biological shield (37). . Reactor water level measurement system according to claim 6, characterized in that the microwave detection unit (30A, 30B) performs a density correction in the water and water level measuring tube (26, 26A, 140, 301) in the reactor pressure vessel (21, 100, 201), 301B, 301D) based on the difference in water temperature. Reactor water level measuring system according to claim 1, characterized in that the float is formed by a magnetized float (60B) having a magnetized part and reflecting an ultrasonic wave or a microwave, the reactor water level measuring system further comprising a gas-liquid interface position reading unit (60B, 61B, 62B, 63B) having a 15-position reader (62B) of a float (60B) disposed along the outer surface of the water level measuring tube (26, 26A, 140, 301, 301B, 301D) and providing a position signal of the float (60B) in response to a magnetized float (60B). 60B) for magnetism, and a cable transfer unit (63B) for transmitting the position signal of the float (60B) to the water level calculating unit (31, 123, 124, 311), and the 20 reactor water level calculating unit (31, 123, 124, 311) using the float (60B) position signal. The reactor water level measuring system according to claim 1, characterized in that the float (58, 60B) contains radioactive material, and the 25 reactor water measuring system further comprises a unit which detects the position of the float (58, 60B) by indicating the float (58, 60B). incoming radiation and 5 calculates the reactor water level float (58, 60B) from the detected position. CNJ Reactor water level measuring system according to claim 1, characterized in that the water level measuring tube (26, 26A, 140, 301, 00 30 301B, 301D) has a window which provides a view inside it, and | the reactor water level measuring system further comprises a unit that takes a picture in the water level measuring tube (26, 26A, 140, 301, 301B, 301D) of the floating float (58, 60B) and calculates the reactor water level float (58, 60B). of ° in the picture, o 00 35 The reactor water level measurement system according to claim 1, characterized in that it further comprises: 55 units which take a picture of a floating float (58, 60B) floating in the water level measuring tube (26, 26A, 140, 301, 301B, 301D) the us tube (26, 26A, 140, 301, 301B, 301D) is interiored with X-rays, neutron radiation, or other radiation, and which calculates the reactor water level float (58, 5 60B) from the image. Reactor water level measurement system according to one of claims 1, 2 or 3, characterized in that the water level calculation unit (31, 123, 124, 311) performs a density correction based on the reactor power. The reactor water level measuring system according to claim 1, characterized in that the water level calculating unit (31, 123, 124, 311) has a temperature calculating unit (59A; 59B) which calculates the water level measuring tube (26, 26A, 140, 301). 301B, 301D) the internal temperature T (Vg (t) * tg + V L (t) * tL) / 2 = l_, depending on the tg represents the gas phase to the propagation time required for the gas-15 phase-side detection unit (40a, 43a, 41; 27A, 28A , 29A, 30A; 27B, 28B, 29B, 30B) between transmitting an ultrasonic wave and receiving a reflection wave, i. shows the liquid phase of the propagation time required for the liquid-phase side of the detection unit (40b, 43b, 41; 40bB, 43bB, 41) made between the transmission and the reflection wave of the ultrasonic wave reception, T represents the water level in the measuring tube (26, 20 26A, 140, 301, 301B, 301D) of the internal temperature, VG (T) represents the ultrasonic wave velocity in the gas phase in the water level measuring tube (26, 26A, 140, 301, 301B, 301D) as a function of internal temperature T only, V1 (T) represents the ultrasonic wave velocity in the liquid phase water measuring tube (26, 26A, 140, 301, 301B). , 301D) as a function of internal temperature T only, and L represents the sum of the gas phase length and liquid phase length in the water level measuring tube (26, 26A, 140, 301, 301B, 301D), and the water level calculation unit (31, 123, 124, 311) calculates the level of reactor water 5 using the ultrasonic wave velocity VG (T) in the gas phase of the water level measuring tube (26, CM ^ 26A, 140, 301, 301B, 301D) and the ultrasonic wave velocity V1 (T) in the water phase. a position measuring tube (26, 26A, 140, 301, 301B, 301D) in the liquid phase defined by the temperature calculation unit (59A; 59B) from lowering the water level measuring tubes ken (26, 26A, 140, 301, 301B, 301D) internal temperature. cm Reactor water level measuring system according to claim 1, characterized in that the water level measuring tube (26, 26A, 140, 301, 2 301B, 301D) has a barbed structure on its outer surface. ^ 35 The reactor water level measuring system according to claim 1, characterized in that the reactor water level measuring system 56 is used in combination with a reactor water level measuring system other than a reactor water level measuring system comprising: a water level measuring tube (26, 26A, 140, 301, 301B, 301D). mounted outside the reactor pressure vessel (21, 100, 201) and comprising a pulling portion communicating with the saturated vapor phase region of the reactor pressure vessel (21, 100, 201) and a reactive aqueous vessel region of the reactor pressure vessel (21, 100, 201) part; gas phase side of the detection unit (40a, 43a, 41; 27A, 28A, 29A, 30A; 27B, 28B, 29B, 30B) which transmits an ultrasonic wave or the microwave from the gas phase 10 in the liquid phase the water level in the measuring tube (26, 26A, 140, 301, 301B, 301D); receiving a reflection wave from the gas-liquid interface and generating a reflection wave signal; The liquid phase side of the detection unit (40b, 43b, 41; 40bB, 43bB, 41) which transmits an ultrasonic wave from the liquid phase to the gas phase the water level in the measurement pipe 15 (26, 26A, 140, 301, 301B, 301D) receives the reflection waves the gas-liquid interface and produce heijastusaaltosignaalin; and water-level calculation unit (31, 123, 124, 311) which calculates the reactor water level by using gas-phase side of the detection unit (40a, 43a, 41; 27A, 28A, 29A, 30A; 27B, 28B, 29B, 30B) heijastusaaltosignaalia produced and liquefied 20-phase side of the detection unit (40b, 43b, 41; 40bB, 43bB, 41) produced heijastusaaltosignaalia. A method for measuring reactor water, which measures the water level in a reactor pressure vessel (21, 100, 201), comprising: providing a water level measuring tube (26, 26A, 140, 301, 25 301B, 301D) having a reactor pressure vessel (21, 100). , 201) a communication part with a saturated vapor phase region and an aqueous part communicating with a water reactor region in the reactor pressure vessel (21, 100, 201); in the gas phase side detection step of transmitting the ultrasonic wave gas 00 30 gas phase into the liquid phase the water level in the measuring tube (26, 26A, 140, 301, 301B, | 301D), receiving a reflection wave of gas-liquid interface and generating reflection c \ j jastusaaltosignaali; No g of a liquid phase side detection step of transmitting the ultrasonic wave liquid ° phase to the gas phase the water level in the measuring tube (26, 26A, 140, 301, 301B, 00 35 301D), receiving a reflection wave of gas-liquid interface and generating reflection jastusaaltosignaali; and 57, the reactor water level calculation step which uses heijastusaaltosignaalia produced in the gas phase side detection step and heijastusaaltosignaalia produced in a liquid phase side of the detecting means, characterized in that the water level in the measuring tube (26, 26A, 140, 301, 301B, 5-301D) are arranged outside reactor pressure vessel (21, 100, 201) and Priva sufaasipuolen the detection step of the reflection wave into the gas-liquid interface-surface, a reflection wave reflected by the float (58, 60B), which floats in the liquid phase of the water level in the measuring tube (26, 26A, 140, 301, 301B, 301D) A reactor water level measuring system for measuring the reactor water level in a reactor pressure vessel (21, 100, 201), comprising: a water level measuring tube (26, 26A, 140, 301, 301B, 301D) communicating with a reactor pressure vessel (21, 100). , 201) with the interior of the at least two locations at different levels so that the reactor water and steam using filing water level measurement usputkeen (26, 26A, 140, 301, 301B, 301D) of the reactor pressure vessel (21, 100, 201), 15 inside; an ultrasonic transceiver unit, which transmits an ultrasonic wave to a water surface in a water level measuring tube (26, 26A, 140, 301, 301B, 301D), receives a reflection wave from the water surface and outputs a reflection wave signal; and 20 water level calculating units (31, 123, 124, 311), which calculates the reactor water level using the time between ultrasonic transmission and reflection wave and ultrasonic wave velocity of the ultrasonic transceiver unit (111, 111a, 111b, 111c, 112, 112a, 112b, 112c, 113, 114a, 115a, 306), characterized in that the water level measuring tube (26, 26A, 140, 301, 301B, 301D) is covered by a thermal insulation (212) surrounding the reactor pressure vessel (21, 100, 201), and the water level calculating unit (31, 123, 124, 311) calculates a correlation value at the CNJ prepared earlier, which indicates the relevant 00 of the reflection wave from the water surface in the water level measuring tube (26, 26A, 140, 301, 301B, 301D). 30 reflection wave components, and the light output produced by the ultrasonic transceiver unit | between the measured wave indicated by the shear wave signal and calculates reactor water based on the Tacson time at the time of correlation peaking. o The reactor water level measurement according to claim 18? a system, characterized in that the water level measuring tube (26, 26A, 140, 301D, 301B, 301D) has a projection portion (305, 305B) which extends downwardly from the water level measuring tube (26, 26A, 140, 301, 301B, 301D). ) the two portions below where the water level measuring tube (26, 26A, 140, 301, 301B, 301D) communicates with the core of the reactor pressure vessel (21, 100, 201). The reactor water level measurement system according to any one of claims 18 to 19, further comprising: a second ultrasonic transceiver unit (111, 111a, 111b, 111c, 112, 112a, 112b, 112c, 113, 114a, 115a, 306 ), which transmits an ultrasonic wave in the radial direction of the water level measuring tube (26, 26A, 140, 301, 301B, 301D) so that the ultrasonic wave is transmitted through the reactor water in the water level measuring tube (26, 26A, 140, 301, 301B, 301D) the water level measuring tube 10 from the inside surface of the usb tube (26, 26A, 140, 301, 301B, 301D) and providing a reflection wave signal, wherein the water level calculating unit (31, 123, 124, 311) calculates the ultrasonic wave velocity VV = 2 * D / T, wherein D represents the diameter of the water level measuring tube (26, 26A, 140, 301, 301B, 301D) and T represents the reflection time produced by the other 15 ultrasonic transceiver units (111, 111a, 111b, 111c, 112, 112a, 112b, 112c, 113, 114a, 115a, 306) hi and calculates the water level of the reactor using the speed of the ultrasonic wave. The reactor water level measuring system according to claim 20, characterized in that the water level measuring tube (26, 26A, 140, 301, 20 301B, 301D) has an ultrasonic reflecting surface which reflects from the second ultrasonic transceiver unit (111, 111a, 111b). 111c, 112, 112a, 112b, 112c, 113, 114a, 115a, 306) in such a way that the reflection direction of the ultrasound wave is parallel to the direction of incident of the ultrasound wave. Reactor water level measuring system according to one of claims 18 to 21, characterized in that the water level measuring tube (26, 26A, 140, 301, 301B, 301D) has two or more parts which communicate with the reactor pressure vessel (21). , 100, 201) with the reactor water area. CM i o cö X cc CL C \ l O O LO O δ CM 59