JP3611285B2 - Concentration measurement system for components to be detected, and reactor cooling water concentration control method and apparatus using the concentration measurement system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for constantly measuring or monitoring the concentration of a component to be detected in a reactor cooling system online, and in particular, the B and Li component concentrations in cooling water in a primary cooling system of a pressurized water reactor are on-line. The present invention relates to a method and an apparatus for measuring or calculating and controlling B and Li component concentrations to specified values based on the measurement results. The present invention also relates to a measurement system for a detection target component used in the method and apparatus as described above, and further relates to a measurement cell used in the measurement system.
[0002]
[Prior art]
As is well known, the reactivity control of a pressurized water reactor (PWR) is performed by changing the boron concentration in the cooling water in the primary cooling system as well as the position of the control rod. Of particular importance. In other words, the water quality management of the primary cooling system of the PWR is to achieve the corrosion suppression of the primary system constituent materials such as Inconel 600 and stainless steel, and hence the reduction of the radioactivity. For this reason, the water quality standard value is set and managed. ing.
[0003]
As described above, boron is added to cooling water for reactivity control in PWR. However, since boron makes water quality acidic, lithium hydroxide is added from the viewpoint of inhibiting corrosion of the primary cooling system constituent materials. By doing so, ph is adjusted. When lithium hydroxide is added to increase ph, the corrosion of Inconel 600 and stainless steel can be kept sufficiently low. However, the amount of lithium hydroxide cannot be increased beyond a certain level in view of Zircaloy corrosion and hydrogen embrittlement. Therefore, lithium concentration management corresponding to the boron concentration is performed, and an example thereof is described in “Nuclear Power Handbook”, pages 186 to 193, published by Ohm Co., Ltd., “Reactor Water Chemistry”.
[0004]
In addition, for the secondary side cooling water and the secondary side water that is converted into steam in the steam generator, water quality management is important for maintaining the soundness of the steam generator heat transfer tube. For secondary water, for example, water quality reference values such as Ca, Mg, Cr, Fe, Cu, Ni, Na, Cl (chlorine) are determined.
[0005]
On the other hand, since the boiling water reactor (BWR) cooling water does not generally perform reactivity control by boron injection, neutral pure water is used. Standards are established based on the degree of involvement of neutral pure water in the materials stainless steel, carbon steel, stellite, inconel and other materials. Therefore, the water quality management of the BWR plant is performed so as to set a reference value of impurities such as silica for the reactor water and the feed water so as not to exceed the reference value.
[0006]
With regard to the conventional water quality management method, the management target substances, for example, B and Li in the cooling water of the pressurized water reactor will be described representatively with reference to FIG. The cooling water sample is manually drawn from the sample line of the PWR plant to the sampling container (a waiting time of about 15 minutes is required for purging the sampling line), and is manually transported to the radiochemical analysis room. The analysis value was obtained by the analysis device of 1 or by manual analysis using a titration method. For convenience, this is referred to as a known analysis method.
[0007]
Although not shown, there is no application example used for measuring the B and Li concentrations in the reactor cooling water, but the following method has been proposed as a microanalysis method using a laser that is considered to be applicable.
(1) An LBS method (laser breakdown method) in which a laser beam is focused on a solid, liquid, or gas sample to convert the component into plasma and the plasma emission is detected to measure a trace component concentration.
(2) LIF method (laser-induced emission method) in which a laser beam having a wavelength corresponding to the electron energy difference of the component to be detected is incident, the emission intensity emitted from the excited measurement target component is detected, and the concentration of the trace component is measured ).
[0008]
[Problems to be solved by the invention]
However, in the known analysis method described above, it is necessary to go through the following process shown in FIG. 12 before obtaining the analysis result.
(1) A certain amount of cooling water sample is taken into a sampling container in a sampling line (sampling chamber) of the reactor cooling system.
(2) Transport the collected sample container to the radiochemical analysis room with the measuring equipment.
(3) B and Li quantitative analysis in the sample is performed in this analysis room. For Li, a manual analysis is carried out by atomic absorption, in which the element is quantified by utilizing the light absorption phenomenon of atoms, which absorbs light of a specific wavelength, and for B, by NaOH titration.
[0009]
Thus, in the conventional known analysis method, since it takes a considerable time (30 to 60 minutes) until the analysis result is obtained from the collection of the sample from the measurement field, the B and Li component concentrations in the reactor cooling water are required. This is a technology far from the realization of rapid measurement and result processing, and often affects the progress of other processes related to the operation of the nuclear power plant, such as delay. Further, when automation of the sample transport process is considered mainly for the above-described known analysis method, a sample specimen transport device, transport piping, device installation facility, and the like are required, resulting in a disadvantage that the device is expensive.
[0010]
In addition, as a conventional measurement method using a laser, there are an LBS method using only a laser beam for plasma generation and an LIF method in which a laser beam having a wavelength corresponding to an electron energy difference of a measurement target component is incident. Each of them has the following drawbacks.
(1) In the conventional LBS method using a pulsed laser beam for plasma generation, a detection limit concentration up to the ppb level cannot be obtained.
(2) Only the conventional LIF method using the excitation pulse laser beam has a great influence on the combined state of the components, so that sufficient quantitative accuracy cannot be ensured.
[0011]
Accordingly, a first object of the present invention is to provide a method and an apparatus that can quickly and accurately measure the concentration of a detection target component in water of a reactor cooling system.
Another object of the present invention is to quickly and accurately measure the B and Li component concentrations in the cooling water in the primary cooling system of the pressurized water reactor online, and based on the measurement results, the B and Li components in the primary cooling system are measured. It is to provide a method and apparatus for controlling a component concentration to a specified value.
Furthermore, an object of the present invention is to provide a measurement system for a detection target component that can be used in the method and apparatus as described above, and a measurement cell used in the measurement system.
[0012]
[Means for Solving the Problems]
In order to achieve the first object described above, first, it is necessary to constantly monitor online the concentration of the component to be detected in the reactor cooling system (sometimes simply referred to as “reactor cooling water concentration”). For this reason, in the first aspect of the present invention, in a nuclear reactor having a cooling system, a method for controlling the concentration of a detection target component in cooling water of the cooling system to a specified value, the The measurement field of the detection target component is set, the pulsed laser light for plasma generation is irradiated to the cooling water of the measurement field, and the detection target component is detected based on the plasma light generated by the irradiation of the pulsed laser light for plasma generation. The concentration value is detected, and the cooling water injection control valve of the cooling system is controlled to open and close by a concentration signal representing the concentration value.
[0013]
According to another aspect of the present invention, the LBS method using a laser and the LIF method are combined. This provides a method and apparatus capable of quantifying the detection target component contained in the reactor cooling water with high accuracy to the level of the ppb order.
In order to achieve the above object, the present invention provides a method for controlling a concentration of a detection target component in cooling water of a cooling system to a specified value in a nuclear reactor having a cooling system, wherein the detection target component is included in the cooling system. The measurement field is set, and the cooling water of the measurement field is irradiated with the pulsed laser beam for plasma generation and the excitation pulsed laser beam for the component to be detected in synchronization, and the irradiation with the pulsed laser beam for plasma generation and the The concentration value of the detection target component is detected based on the emission intensity emitted from the detection target component by irradiation with the excitation pulse laser beam, and the cooling water injection control valve of the cooling system is controlled to open and close by the concentration signal representing the concentration value. A concentration control method for a detection target component is provided.
[0014]
In order to achieve the above object, the present invention is an apparatus for controlling a concentration of a detection target component in cooling water of a cooling system to a specified value in a nuclear reactor having a cooling system, and is set in the cooling system. A plasma cell for irradiating the measurement cell disposed in the measurement field of the detection target component and the cooling laser water of the measurement cell with the plasma generation pulse laser beam and the excitation pulse laser beam of the detection target component in synchronization with each other The actual value of the concentration of the detection target component is continuously based on the pulse laser and the excitation pulse laser, and the emission intensity emitted from the detection target component by the irradiation of the plasma generation pulse laser light and the excitation pulse laser light. Connected to the cooling system, calculating means for automatically calculating, determining means for determining whether the actual value of the concentration of the detection target component is acceptable for the specified value, and The control valve of the detected detection target component adjustment line and the control valve are controlled to open and close so that the actual value returns to the specified value when the actual value of the concentration of the detection target component is determined to be an abnormal value. And a concentration control device for the detection target component.
[0015]
The present invention according to another aspect relates to a pressurized water reactor that communicates with a steam generator through a primary cooling system including a high-temperature side pipe and a low-temperature side pipe. In the reactor, B, Li in the cooling water of the primary cooling system is provided. An apparatus for controlling the concentration of a component to a specified value, the measurement cell being arranged at the measurement field of the B and Li components set on the high temperature side of the primary cooling system, and the cooling water of the measurement cell The plasma generation pulse laser and the excitation pulse laser that irradiate the plasma generation pulse laser beam and the excitation pulse laser light of the B and Li components in synchronization with each other, and the irradiation and excitation of the plasma generation pulse laser light, respectively. Calculating means for calculating the actual values of the concentrations of the B and Li components based on the emission intensity emitted from the B and Li components by the irradiation of the pulse laser light for use, and before the primary cooling system When the actual values of the B and Li component adjustment lines connected to the low temperature side pipe and the B and Li component concentrations are determined to be abnormal values, the actual values are restored to the specified values. And a control means for controlling opening and closing of the control valve.
[0016]
Specifically, the laser beam is irradiated in two stages (LBS method) in order to improve the analysis accuracy for the B and Li components. A pulsed laser beam for plasma generation is focused / incident on the reactor cooling water, the components in the reactor cooling water are turned into plasma, and after a certain period of time has been generated, the plasma is induced in the plasma induced by the previous laser beam. Further, a pulse laser beam for excitation is incident, and B and Li components existing in the plasma are laser excited. The light emission intensity emitted by the B and Li components excited by the irradiation of the plasma generation pulse laser light and the excitation pulse laser light is detected using a photodetector, and the light emission intensity emitted by the B and Li components exists in the plasma portion. By correcting with the component composition, the B and Li components contained in the reactor cooling water as a sample are immediately and directly quantified to a minute level of ppb order.
[0017]
The present invention also provides a measurement cell disposed in a measurement field so as to allow water flow and laser light penetration, and a pulsed laser beam for plasma generation having a pulse energy of 10 to 40 mJ with respect to water in the measurement cell. A laser for generating plasma, an excitation laser for emitting a pulse laser beam for excitation of a detection target component contained in the water in synchronization with the pulse laser beam for plasma generation, and a pulse laser beam for plasma generation Provided is a concentration measurement system for a detection target component, comprising: calculation means for calculating an actual value of the concentration of the detection target component based on the intensity of light emitted from the detection target component by irradiation and irradiation of the excitation pulse laser beam. . Here, as described in claim 7, it is preferable that an emission interval of the plasma generation pulse laser beam and the excitation pulse laser beam is in a range of 1 μs to 13 μs. In addition, as described in claim 8, 0.1 to 1 μs after irradiation with the pulsed laser beam for plasma generation or the pulsed laser beam for excitation, the component to be detected is re-excited with a wavelength width of 0.1 hm or less. It is preferable to further include a wavelength tunable laser that irradiates a laser beam adjusted to a wavelength to be adjusted (LIF method).
[0018]
Further, it is preferable that the calculation means is a computer and corrects the emission intensity emitted from the detection target component by irradiation with the excitation pulse laser beam based on the emission line emitted from the oxygen atom.
[0019]
According to the present invention, the measurement cell is substantially hexahedron, and light transmitting glass is provided on the first surface on which the pulsed laser beam for plasma generation and the pulsed laser beam for excitation are incident via a sealing means. The second surface facing the first surface is provided with a laser trap plate via a sealing means, and the two surfaces facing each other except for the first surface and the second surface flow the water. An inlet and an outlet that allow the light to pass through are provided, and light-transmitting glass that transmits the plasma light and the light emission is provided on the remaining two surfaces facing each other through a sealing means.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or corresponding parts. Further, as will be understood from the following description, the present invention is not limited to this embodiment, and various modifications are possible.
[0021]
FIG. 1 schematically shows a control system of a pressurized water reactor plant to which the method and apparatus according to the present invention is applied. In a solid containment vessel 1, a steam generator 2 and a reactor 3 are arranged. ing. The primary cooling water sent into the nuclear reactor 3 by the cooling water pump 5 provided in the pipe 8 is heated to become high temperature and high pressure, and enters the water chamber inlet side 2 a via the pipe 6, While flowing through a large number of heat transfer tubes 2b, the feed water supplied from the piping 7 is heated and cooled, and exits the steam generator 2 from the outlet side 2c of the water chamber. Then, it is circulated again to the reactor 3 by the cooling water pump 5.
[0022]
The feed water heated in the steam generator becomes steam and is supplied to the steam turbine (not shown) through the pipe 9. Further, a primary cooling system pipe 6 extending from the high temperature side of the reactor 3 to the steam generator 2 has a pressurizer for maintaining the cooling water in a pressurized state exceeding the saturation pressure in order to suppress the boiling of the cooling water in the core. 4 is provided.
[0023]
The low-temperature side pipe 8 constituting the primary cooling system includes an extraction line 10a for extracting a part of the cooling water upstream of the cooling water pump 5 and a part of the cooling water downstream of the cooling water pump 5. A chemical volume control system 10 including a filling line 10b returning to the pipe 8 on the side is connected. The extraction line 10a of the chemical volume control system 10 is provided with a desalting tower 11 and a volume control tank 12, and the filling line 10b includes a boric acid tank 14, a primary chemical tank 15 and the like in addition to a filling pump 13. The functions of the chemical volume control system 10 are provided to refill the primary cooling system with cooling water, remove corrosion products and fission products in the cooling water, adjust boric acid concentration, and the like. The extraction line 10a is also provided with a control valve 37, which will be described later.
[0024]
In such a pressurized water reactor plant, for example, according to the present invention, an apparatus for managing or controlling the B and Li component concentrations of the primary cooling water, an apparatus for generating pulsed laser light and irradiating the cooling water of the primary cooling system, An apparatus for finally calculating the B and Li component concentrations from the information obtained by this irradiation, and an apparatus for adjusting the amounts of B and Li in the primary cooling system based on the calculated B and Li component concentrations Is provided. The measurement field of the apparatus for irradiating the cooling water with laser light is, for example, in the middle of the high temperature side pipe 6 of the primary cooling system or on the outer peripheral surface of the liquid phase part of the pressurizer 4 in FIG. , (2) can be set.
[0025]
Next, FIG. 2 shows an outline of an apparatus 20 for managing or controlling the B and Li component concentrations of, for example, primary cooling water according to the present invention. In FIG. 2, the apparatus 20 uses a laser beam emitted from a pulsed laser 21 for plasma generation in a reactor cooling water in a measurement cell provided in a measurement field 25 using mirrors 22 and 23, a lens 28, and the like. The chemical species existing in the measurement cell are converted into plasma as illustrated in FIG. The laser output of the plasma generating pulse laser 21 is 10 to 40 mJ in the embodiment of the present invention. FIG. 10 shows experimental results of laser output and signal intensity in the case of Li. From this result, it is preferable that the laser output be 10 to 40 mJ so as to be compatible with plasma in liquid. I know that there is. The output of the pulse laser 26 for selective excitation of B and Li for increasing the emission intensity of the B and Li components in the cooling water after a certain time in synchronization with the laser beam emission from the plasma generation pulse laser 21 is as follows. As described above, the light is incident on the plasma induced through the mirrors 22 and 23 and the lens 28 as shown in FIG. 7B through the mirror 27 and the like. FIG. 11 is an experimental result of the present invention showing the relationship between the emission interval of the pulse laser beam for plasma generation and the excitation pulse laser beam and the signal intensity in the case of Li, and the emission interval or pulse interval is 1 μs to 13 μs. It is preferably 1.2 μs to 8.2 μs, more preferably 1.8 μs to 6.0 μs. Note that although the unit is omitted from the signal intensity on the vertical axis in FIGS. 10 and 11, this may be considered as a signal intensity ratio.
[0026]
After detecting the plasma light generated by the laser beam for plasma generation and identifying the component composition of the plasma part, the emission intensity emitted by the B and Li components excited by the irradiation of the pulse laser beam for B and Li excitation is measured. And using a detector. That is, in FIG. 2 and FIG. 3, the light emitted by B and Li excited by the above-described plasma light emission and component excitation laser light is collected by the lenses 29a and 29b, and the respective lights are optical fibers 30a and 30b. To the spectrometers 31a and 31b. A part of the light reflected by the mirror 23 is converted into a laser output by the power meter 33 and sent to the personal computer 34b. The personal computer 34b is connected to the detector 32b and is also connected to another personal computer 34a. The personal computer 34b outputs data to a monitor (not shown) and displays the Li and B concentrations as digital values, for example, every 10 minutes. can do. The emission spectra emitted by the B and Li components are measured by the spectroscope 31b and the detector 32b, sent to the personal computer 34b, and the peak intensities I of Li and B _B , I _Li Is read. On the other hand, the emission spectrum of oxygen (O) is measured by the personal computer 34a based on the inputs from the spectroscope 31a and the detector 32a, and the O peak intensity I _O Is read, and the read O peak intensity I _O Is sent to the personal computer 34b. In this way, each signal is transferred to the computer 34b where the O peak intensity I _O Peak intensity I for _B , I _Li Corrected peak intensity I corrected by taking the ratio of _Li *, I _B By obtaining * and multiplying that value by fLi, which is the slope of the Li calibration curve, and fB, which is the slope of the B calibration curve, Li concentration (CLi) and B concentration (CB) can be obtained. As an example, FIG. 8 illustrates an emission spectrum of an aqueous Li solution.
[0027]
In this way, the component composition of the measurement field 25 is obtained from the signal of the plasma emission, the emission intensity is corrected based on the information, and the concentrations of the B and Li components existing in the measurement field 25 are calculated. In this way, the B and Li concentrations in the reactor cooling water are measured with high accuracy to the ppb order by correcting the emission intensity emitted by the B and Li components with the oxygen emission line that is the component composition of the plasma part. 35 is a known synchronizing device that synchronizes the oscillation of the pulse laser 21 for plasma generation 21 and the pulse laser 26 for selective excitation of B and Li and the operation of the detectors 32a and 32b.
[0028]
Examples of the wavelengths of the pulsed laser beam for plasma generation and the pulsed laser beam for component excitation used in the present invention are shown below, but this is only used because the YAG laser can be easily obtained at a low cost, Of course, other laser beams may be used.
Laser wavelength for plasma and component excitation ...
1064nm (YAG laser fundamental wave)
532 nm (second harmonic of YAG laser) or
355 nm (third harmonic of YAG laser)
[0029]
As can be seen from the above description, the present invention combines the LBS method and the LIF method. By this combination, it is possible to eliminate each drawback. Specifically, since the temperature of the local location is raised to 10000 ° C. to 20000 ° C. with the first plasma generating laser beam, almost all chemical species are in an atomic state. At this time, it is not necessary to consider the change of the excitation wavelength due to the bonding state of the chemical species. The concentration of B and Li can be obtained only by injecting the laser beam for exciting the plasmaized B and Li atoms. Satisfy the measurement. That is, although the system uses the LBS method in two stages, the detection sensitivity is greatly improved (about 3 to 5 digits) as compared with the case of the LBS method in one stage.
[0030]
Next, returning to FIG. 1 again, an application example in the nuclear power plant of the present invention will be described. As described above, the measurement field 25 is set on a part of the high-temperature side pipe 6 of the primary cooling system or the outer peripheral surface of the liquid phase part of the pressurizer 4, and here, the LBS two-stage B, Li component concentration control method or A component concentration measurement system 20a (a portion surrounded by a chain line in FIG. 2) of the apparatus 20 is introduced. The B and Li concentrations in the reactor cooling water must always be kept at a certain specified value for reasons such as reactor control. Therefore, the controller 20 for the B and Li component concentrations is linked to the chemical volume control system 10, and the dilution / requirement of the B and Li components is required based on the actual measured values of the B and Li concentrations and the predetermined values to be maintained. The concentration and removal amount is calculated and displayed to the nuclear power plant operator.
[0031]
That is, the analysis result obtained in accordance with the above measurement procedure is displayed in concentration on a control panel indicating unit (not shown) that can be arranged in the central control room 36 of the nuclear power plant, and further the computer of the central control room 36 When it is determined that a dilution / removal / concentration operation related to the volume control system 10 is necessary by performing a comparative evaluation with the concentration reference value at the time of measurement for B and Li after being processed in 34a and 34b. In addition to displaying the specific indication value again on the control plate indication portion of the central control chamber 36, based on the indication value, the control valve 37 provided in the extraction line 10a of the chemical volume control system 10 is opened and closed, The amount of water passing through the extraction line 10a is controlled. That is, when the measured or detected concentration value becomes lower than the lower limit value of the set range, the control valve 37 is opened. Conversely, when the measured or detected concentration value becomes higher than the upper limit value of the set range, the control valve 37 is closed.
[0032]
Thus, while setting the measurement field of the measurement system 20a of the B, Li component concentration of the LBS two-stage method to the high temperature side pipe 6 of the reactor primary cooling system, based on the computer processing of the analysis result of the measurement system 20a, By controlling the control valve 37 provided in the cooling water extraction line 10a of the chemical volume control system 10 connected to the low temperature side pipe 8 of the primary cooling system, real time measurement of B and Li component concentrations in the reactor cooling water is possible. As a result, the B and Li concentration values of the primary cooling system can always be processed online, so that the reactivity control and water quality management of the reactor can be operated more efficiently. This also shortens the process period for periodic inspections, etc. Connected.
[0033]
In this case, as the measurement cell 40 provided in a measurement field, what is shown in FIG.5 and FIG.6 is suitable. 5 and 6, the measurement cell 40 is substantially a regular hexahedron, and in the embodiment, the inlet side flow pipe 41 a for cooling water, which is usually 70 to 80 ° C., which is sample water on the two upper and lower surfaces facing each other. , The outlet side flow pipe 41b is attached (FIG. 6), and the surface on which the plasma generating pulse laser beam and the excitation pulse laser beam are incident is made of rubber or plastic which is sealing means or vibration preventing means. A light transmission glass 43 is provided through such an O-ring 42. In addition, a laser trap plate 44 is provided on the surface facing the light transmitting glass 43 through the same sealing means 42. The laser trap plate 44 is preferably a Teflon plate having a high trapping effect, and the measurement cell body and the flow pipe are preferably made of stainless steel. Light transmitting glasses 45 and 46 that transmit plasma light and light emission are provided on the remaining two surfaces facing each other through similar sealing means 42 (FIG. 5).
[0034]
In addition, as shown in FIG. 4, in order to further improve the measurement sensitivity, the wavelength width is 0.1 hm or less after 0.1 to 1 μs after irradiation with the plasma generation pulse laser beam or the excitation pulse laser beam. A tunable laser 50 that irradiates a laser beam adjusted to a wavelength for exciting the component can be further provided. The wavelength tunable laser 50 is also connected to the synchronizing device 35, and the laser light from the wavelength tunable laser 50 is irradiated to the cooling water in the measurement cell via the mirrors 51 and 52, the above-described mirrors 22 and 23, and the like. If this LBS / LIF combined method is used, the detection sensitivity can be further improved.
B, Li selective excitation laser wavelength ...
B: 208.89 nm or 249.68 nm
Li: 274.12 nm, 323.26 nm or 670.78
[0035]
【The invention's effect】
According to the present invention, in a nuclear reactor having a cooling system, a method for controlling the concentration of a detection target component in cooling water of the cooling system to a specified value, wherein the measurement field of the detection target component is set in the cooling system And irradiating the cooling water of the measurement field with a pulsed laser beam for plasma generation, detecting a concentration value of the component to be detected based on the plasma light generated by the irradiation of the pulsed laser beam for plasma generation, The cooling water injection control valve of the cooling system is controlled to open and close by a concentration signal representing the value. In addition, according to the control method of the present invention, the measurement field of the detection target component is set in the cooling system, and the pulsed laser beam for plasma generation and the excitation pulse laser beam of the detection target component are synchronized with the cooling water of the measurement field. And detecting the concentration value of the detection target component based on the plasma light generated by the irradiation of the plasma generation pulse laser light and the emission intensity emitted from the detection target component by the irradiation of the excitation pulse laser light. Then, the cooling water injection control valve of the cooling system is controlled to open and close by a concentration signal representing the concentration value. Therefore, according to the present invention, the concentration value of the cooling system can always be processed online, so that the reactivity control and water quality management of the reactor can be operated more efficiently, which shortens the process period such as periodic inspection. It leads to.
[0036]
In addition, workers in charge of water quality management of reactor cooling water can avoid the possibility of exposure from radioactive corrosion products contained in the sample during sampling, sample transportation, and analysis. It also contributes greatly.
Furthermore, since the concentration measurement by the above laser is established, the time required for the collection of the work sample in the conventional method, the transportation to the analyzer and the measurement work itself is eliminated. The concentration of components can be grasped in real time, and work related to concentration management becomes efficient.
[0037]
Further, as in another embodiment of the present invention, if the pulse energy of the plasma generation pulse laser beam emitted to the water in the measurement cell is set to 10 to 40 mJ, the detection target component in the cooling water can be detected. Therefore, it is possible to effectively detect components in the cooling water. As in the embodiment of the present invention, the measurement sensitivity is improved by setting the emission intervals of the plasma generation pulse laser beam and the excitation pulse laser beam in the range of 1 μs to 13 μs. In addition, as in the embodiment of the present invention, the wavelength width is adjusted to a wavelength that excites the detection target component with a wavelength width of 0.1 hm or less 0.1 to 1 μs after irradiation with the pulsed laser beam for generating plasma or the pulsed laser beam for excitation. The measurement sensitivity can be further improved by providing a wavelength tunable laser that emits the laser beam.
[0038]
Further, the measurement accuracy can be further improved by correcting the emission intensity emitted from the detection target component by irradiation with the excitation pulse laser beam based on the emission line emitted from the oxygen atom.
[0039]
According to another aspect of the present invention, the measurement cell is provided with a laser trap plate via a sealing means on a surface opposite to a surface on which the plasma generation pulse laser beam and the excitation pulse laser beam are incident. Therefore, the laser beam can be effectively trapped, and the sealing means can prevent water leakage and absorb vibration.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a pressurized water reactor plant to which a concentration control method and apparatus for detection target components according to an embodiment of the present invention is applied.
FIG. 2 is a schematic diagram showing a concentration measuring device for a detection target component of the present invention.
FIG. 3 is an explanatory diagram illustrating a procedure executed by the concentration control apparatus of FIG. 2;
FIG. 4 is a schematic diagram showing a concentration measuring apparatus with higher sensitivity of the detection target component of the present invention.
5 is a cross-sectional view of a measurement cell used in the concentration control apparatus of FIGS. 2 and 4. FIG.
6 is a side view of a measurement cell used in the concentration control apparatus of FIGS. 2 and 4. FIG.
7A is a conceptual diagram of the measurement principle of the present invention showing an LBS method application process, and FIG. 7B is an LIF application process.
FIG. 8 is a graph showing the relationship between the wavelength and intensity (%) of the Li aqueous solution emission spectrum.
FIG. 9 is a chart showing the relationship between the elapsed time from YAG laser irradiation and the signal intensity in the case of Li.
FIG. 10 is a chart showing the relationship between laser output and signal intensity for Li.
FIG. 11 is a chart showing the relationship between pulse interval and signal intensity for Li.
FIG. 12 is an explanatory diagram illustrating a conventional procedure for measuring B and Li concentrations in a nuclear power plant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Steam generator, 3 ... Pressurized water reactor, 4 ... Pressurizer, 6 ... High temperature side piping of primary cooling system, 8 ... Low temperature side piping of primary cooling system, 10 ... Chemical volume control system, 10a ... Extraction line, DESCRIPTION OF SYMBOLS 10b ... Filling line, 20 ... Concentration control apparatus, 21 ... Plasma generation pulse laser, 25 ... Measurement field, 26 ... B, Li selective excitation pulse laser, 34a, 34b ... Computer (calculation means), 37 ... Control valve, 40 ... measurement cell, 41a ... inlet side flow pipe (inlet), 41b ... outlet side flow pipe (outlet), 42 ... O-ring (sealing means), 43, 45, 46 ... quartz glass (light transmission glass) ) 44... Laser trap plate (Teflon plate) 50. Tunable laser.

Claims (6)

A measuring cell arranged in the measuring field to allow water flow and laser light penetration;
A plasma generating laser that emits a pulsed laser beam for generating plasma with a pulse energy of 10 to 40 mJ to water in the measurement cell;
An excitation laser that emits the excitation pulse laser beam of the detection target component contained in the water in synchronization with the plasma generation pulse laser beam;
The detection target component is corrected by correcting emission intensity emitted from the detection target component by irradiation of the plasma generation pulse laser light and the excitation pulse laser light based on an emission line emitted from an oxygen atom. Calculating means for calculating the actual value of the concentration of
A concentration measurement system for a component to be detected in which a discharge interval between the plasma generation pulse laser beam and the excitation pulse laser beam is in a range of 1 μs to 13 μs. After 0.1 to 1 μs after irradiation with the pulsed laser light for plasma generation or the excitation pulsed laser light, a laser beam adjusted to a wavelength for reexciting the detection target component with a wavelength width of 0.1 nm or less is applied. The concentration measurement system according to claim 1, further comprising a wavelength tunable laser. The measurement cell is substantially a hexahedron, and a light transmitting glass is provided through a sealing means on a first surface on which the pulsed laser beam for plasma generation and the pulsed laser beam for excitation are incident,
A laser trap plate is provided on the second surface facing the first surface via a sealing means,
The two surfaces facing each other except the first surface and the second surface are provided with an inlet and an outlet allowing the water flow,
3. The concentration measuring system according to claim 1 , wherein light-transmitting glass that transmits the plasma light and the light emission is provided on the remaining two surfaces facing each other through a sealing unit. In a nuclear reactor having a cooling system, a method of controlling the concentration of a detection target component in cooling water of the cooling system to a specified value,
A measurement field of the detection target component is set in the cooling system, and an actual value of the concentration of the detection target component is detected using the concentration measurement system according to any one of claims 1 to 3 .
A detection target component concentration control method for controlling opening and closing of a control valve of a detection target component adjustment line connected to the cooling system based on computer processing of the actual value and the specified value. In a nuclear reactor having a cooling system, an apparatus for controlling the concentration of a detection target component in cooling water of the cooling system to a specified value,
The concentration measurement system according to any one of claims 1 to 3 , wherein a measurement field of the detection target component is set in the cooling system;
Determination means for determining whether an actual value of the concentration of the detection target component detected by the concentration measurement system is acceptable for the specified value;
A control valve of a detection target component adjustment line connected to the cooling system;
Concentration of the detection target component, comprising control means for controlling the opening and closing of the control valve so that the actual value returns to the specified value when the actual value of the concentration of the detection target component is determined to be an abnormal value. Control device. In a pressurized water reactor that communicates with a steam generator through a primary cooling system comprising a high temperature side pipe and a low temperature side pipe, it is an apparatus for controlling the concentrations of B and Li components in the cooling water of the primary cooling system to specified values. And
The concentration measurement system according to any one of claims 1 to 3 , wherein a measurement field for the B and Li components is set on a high temperature side of the primary cooling system;
A control valve of a B, Li component adjustment line connected to the low temperature side pipe of the primary cooling system;
Control means for controlling the opening and closing of the control valve so that the actual value returns to the specified value when the actual value of the concentration of the B and Li components detected by the concentration measurement system is determined to be an abnormal value; A reactor cooling water concentration control device.

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