JP6659225B2 - Apparatus for estimating water level in reactor pressure vessel and method for estimating water level in reactor pressure vessel - Google Patents

Description

  An embodiment of the present invention relates to a reactor pressure vessel water level estimation device and a reactor pressure vessel water level estimation method for estimating a temporal change of a water level in a reactor pressure vessel.

  Generally, as a method of measuring a reactor water level in a boiling water reactor (BWR), a technique of measuring a water level using a differential pressure is used. This method measures the water level by measuring the differential pressure with a differential pressure gauge that connects the gas phase to the upper part and the liquid part to the lower part by providing measurement nozzles at the upper and lower parts of the reactor pressure vessel. Is what you do. In this case, a condensation tank is provided in the line from the upper measurement nozzle to the differential pressure gauge to condense steam, and the instrumentation pipe to the differential pressure gauge is filled with condensed water to avoid a water level fluctuation event in the instrumentation pipe, and to reduce the actual water level. The change in the reactor water level is measured by obtaining the change in the differential pressure by the change in the pressure of the lower nozzle due to the fluctuation.

JP-A-10-274554

  The reactor water level, that is, the water level in the reactor pressure vessel, is a process quantity directly related to the safe operation of the reactor facility, and must be constantly monitored. In the event of a severe accident at the reactor facility, the water level cannot be measured due to the failure of the differential pressure gauge mentioned above, or the evaporation of water in the condensing tank due to boiling during depressurization, and the reactor water level may not be monitored. There is. Actually, in a serious accident, there is an example in which the differential pressure type water gauge cannot be measured due to evaporation of water in the condensing tank, and the reactor water level cannot be monitored.

  Also, for example, in Japan, if it becomes difficult to measure parameters that need to be monitored in order to deal with a serious accident, etc., equipment that can grasp useful information for estimating the parameters will be provided. Must be established. As described above, when the reactor water level cannot be measured, it is required to provide an estimating means using alternative parameters.

  Therefore, in the event of an accident at the reactor facility, the operator may not be able to measure the reactor water level as described above, or the reactor water level indication may not increase as much as the amount of water injected into the reactor. When there is a suspicion that water is leaking from the vessel, the reactor water level is estimated from parameters other than the reactor water level, such as reactor pressure, water injection amount, and water injection temperature. However, it is difficult for the operator to collect the parameters that change every moment and calculate the water level manually by hand in response to an emergency requiring an emergency.

  An embodiment of the present invention has been made in consideration of such circumstances, and has an object to enable monitoring of a reactor water level separately from water level measurement by a water level gauge.

In order to achieve the above-mentioned object, the present embodiment is provided in a water injection pipe for guiding a water pressure measured by a pressure gauge provided in a reactor pressure vessel in which a reactor core is housed and water is injected and steam is generated. A reactor pressure vessel water level estimating device for estimating a temporal change in the water level of the cooling water of the reactor pressure vessel based on outputs of a temperature measurement value by a thermometer and a volume flow measurement value by a flow meter. A decay heat determining unit that determines a decay heat Q generated from the core for a time after receiving the reactor stop system operation signal, and a density ρin and an enthalpy Hin of the water injection based on a measured value of the temperature of the water injection. a water injection state quantity determination unit determining a water injection flow rate determining unit for determining the injection mass flow Win based on the density ρin and the injection of the volume flow measurement Gin, based on a measured value of the pressure gauge The saturated water enthalpy Hf, the saturated water density ρs, and the latent heat of vaporization Hfg of the retained water in the liquid phase in the reactor pressure vessel, the decay heat Q, the injection mass flow rate Win, , said enthalpy Hin, the steam generation amount calculating unit that calculates the saturated water enthalpy Hf and the latent heat of vaporization Hfg Toka et steam generation amount Wg, the injection mass flow Win, the steam generation amount Wg and the saturated water density ρs And a water level determining unit that determines an estimated water level in the reactor pressure vessel based on the above.

Further, in the present embodiment, a pressure measurement value provided by a pressure gauge provided in a reactor pressure vessel in which a reactor core is housed and water is injected and steam is generated, and a temperature measurement is provided by a thermometer provided in a water injection pipe for guiding the water injection. A reactor pressure vessel water level estimation method for estimating a temporal change in the water level of the cooling water in the reactor pressure vessel based on the output of the measured value and the volume flow measurement value by the flow meter,
Decay heat determination unit, and the decay heat determining step of determining a decay heat Q generated from the core for the time after receiving the reactor shutdown system operation signal, injection state amount determining unit is a measurement of the temperature of the water injection wherein determining the density ρin and enthalpy Hin water injection, the water injection flow rate determining section, and a water injection state amount determining step of determining the injection mass flow Win based on the water injection volumetric flow measurements Gin and the density ρin based on, A saturated state quantity determining unit that determines a saturated water enthalpy Hf, a saturated water density ρs, and a latent heat of vaporization Hfg of the retained water in a liquid phase in the reactor pressure vessel based on the measurement value of the pressure gauge. Step, the steam generation amount calculation unit calculates the decay heat Q, the water injection mass flow rate Win, the enthalpy Hin, the saturated water enthalpy Hf, and the evaporation latent heat H. a steam generation amount calculating step of calculating the g Toka et steam generation amount Wg, the water level determination unit, the injection mass flow Win, the steam generation amount Wg and the saturated water density ρs and the reactor pressure vessel on the basis of the And a water level determining step of determining the estimated water level.

  According to the embodiment of the present invention, it becomes possible to monitor the reactor water level separately from the water level measurement by the water level meter.

FIG. 1 is a longitudinal sectional view showing a configuration around a reactor pressure vessel including a reactor pressure vessel water level estimation device according to a first embodiment. It is a block diagram showing composition of a reactor pressure vessel water level estimating device concerning a 1st embodiment. FIG. 3 is a block diagram illustrating a configuration of a decay heat determination unit of the reactor pressure vessel water level estimation device according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of a water injection state quantity determination unit of the reactor pressure vessel water level estimation device according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of a saturated water state determination unit of the reactor pressure vessel water level estimation device according to the first embodiment. It is a block diagram showing contents of a steam generation amount calculation part and a water level determination part of a reactor pressure vessel water level estimation device according to a first embodiment. It is a figure showing an example of a screen display of a trend display of a measured value and an estimated value of a reactor water level. 5 is a conceptual graph for explaining a method of correcting an estimated value based on a measured value of a reactor water level. FIG. 3 is a flowchart illustrating a procedure of a method for estimating a water level in a reactor pressure vessel according to the first embodiment. It is a block diagram showing composition of a reactor pressure vessel water level estimating device concerning a 2nd embodiment. It is a block diagram showing composition of a reactor pressure vessel water level estimating device concerning a 3rd embodiment.

  Hereinafter, a water level estimation device and a method for estimating a water level in a reactor pressure vessel according to an embodiment of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by the same reference numerals, and redundant description will be omitted.

[First Embodiment]
Hereinafter, the present embodiment will be described using a BWR reactor facility as an example. FIG. 1 is a longitudinal sectional view showing a configuration around a reactor pressure vessel including a reactor pressure vessel water level estimation device according to the first embodiment. A reactor pressure vessel 2 containing the reactor core 1 is provided, and a reactor containment vessel 3 containing the reactor pressure vessel 2 is provided outside the reactor pressure vessel 2.

  A coolant 5 is contained in the reactor pressure vessel 2. The coolant 5 is divided into a liquid phase part 5a and a gas phase part 5b. A liquid phase portion 5a is provided in a lower portion of the reactor pressure vessel 2, and a gas phase portion 5b is provided in an upper portion of the reactor pressure vessel 2.

  The liquid surface 5c of the coolant 5 at the interface between the liquid phase portion 5a and the gas phase portion 5b is kept constant during normal operation. A water level gauge 4 is provided to monitor the level of the liquid level 5c, that is, the water level. The water level gauge 4 is usually of a differential pressure type. The liquid phase portion 5a in the reactor pressure vessel 2 and the water level gauge 4 are connected by a pressure guiding tube that penetrates the reactor containment vessel 3 in an airtight manner. Similarly, the gas phase portion 5 b in the reactor pressure vessel 2 and the water level gauge 4 are connected by a pressure guiding tube that passes through the containment vessel 3 in an airtight manner. A condensing tank 4a is provided in a portion of the pressure guiding tube from the gas phase part 5b inside the reactor containment vessel 3 to keep the height of the condensed water in the pressure guiding tube constant. The water level gauge 4 is provided inside a reactor building (not shown) outside the reactor containment vessel 3.

  A pressure gauge 6 is provided to measure the pressure of the gas phase portion 5b of the reactor pressure vessel 2. The pressure gauge 6 is provided outside the containment vessel 3 and inside the reactor building. The reactor pressure vessel 2 and the pressure gauge 6 are connected by a pressure guiding tube that penetrates the containment vessel 3 in an airtight manner.

  A water injection pipe 7 is connected to the reactor pressure vessel 2. In the event of a serious accident in which the coolant in the reactor pressure vessel 2 is discharged into the containment vessel 3, for example, the cooling water stored in a storage tank (not shown) outside the reactor building is replaced with a water injection pipe. The fuel is injected into the reactor pressure vessel 2 via. The water injection pipe 7 is provided with a flow rate measuring element 8a such as a flow nozzle or a venturi, and the flow meter 8 outputs a flow rate signal based on the differential pressure. Further, the water injection pipe 7 is provided with a thermometer 9 for measuring the temperature of the cooling water in the water injection pipe 7. The flow meter 8 and the thermometer 9 are provided outside the containment vessel 3.

  The reactor pressure vessel 2 is provided with a steam pipe 10. At the time of a serious accident, for example, it becomes a steam path to be supplied to a steam turbine (not shown) for driving a pump (not shown) for pumping cooling water.

  A pipe for supplying cooling water (not shown) is connected to the reactor pressure vessel 2, and serves as a path for supplying cooling water into the reactor pressure vessel 2 during normal operation. The piping for supplying the cooling water is a water supply pipe. At the time of a serious accident, the supply of the cooling water from the normal cooling water supply pipe is stopped.

  Further, a piping for outflow of cooling water (not shown) is connected to the reactor pressure vessel 2, and serves as a path through which cooling water flows out of the reactor pressure vessel 2 during normal operation. The piping for cooling water outflow is the main steam pipe in the case of BWR. At the time of a serious accident, the outflow of the cooling water from the ordinary cooling water outflow pipe is stopped.

  Therefore, in the state at the time of the accident, the supply of the cooling water from the normal cooling water supply pipe and the outflow of the cooling water from the normal cooling water outflow pipe need not be considered.

  The reactor pressure vessel water level estimating device 20 receives the outputs from the pressure gauge 6, the flow meter 8, and the thermometer 9 and estimates the water level in the reactor pressure vessel 2. Further, the reactor pressure vessel water level estimation device 20 outputs the estimation result of the water level to the display device 30, and the display device 30 displays the estimation result.

  FIG. 2 is a block diagram showing the configuration of the reactor pressure vessel water level estimation device 20 according to the first embodiment. The reactor pressure vessel water level estimation device 20 includes a decay heat determination unit 22, a water injection state amount determination unit 23, a water injection flow rate determination unit 24, a saturation state amount determination unit 25, a water level storage unit 26, a steam generation amount calculation unit 27, and It has a water level determination unit 28.

  FIG. 3 is a block diagram showing a configuration of the decay heat determining unit 22 of the reactor pressure vessel water level estimation device 20. The decay heat determination unit 22 has a built-in clock 22a, and receives a signal indicating that a reactor stop signal, which is an operation signal of a reactor stop system (not shown), has been issued, and the time from the point when the reactor was shut down. Count. Further, the decay heat determination unit 22 has a decay heat table 22b that associates the time after the reactor shutdown with the decay heat Q. As described above, the decay heat determining unit 22 determines the value of the decay heat Q generated from the core fuel after receiving the reactor shutdown signal.

  The signal indicating that the reactor stop signal, which is the operation signal of the reactor stop system, has been issued, does not need to be the signal of the reactor stop system. Further, the clock 22a may be manually started by an operator, for example.

  Alternatively, when the water level estimating device 20 in the reactor pressure vessel is to be activated at a point in time when a considerable time has elapsed after the reactor shutdown, the elapsed time after the reactor shutdown at that time is input. Is also good. In this case, it is conceivable that the inventory of the cooling water in the reactor pressure vessel 2 has changed from the normal operation state due to the transient event after the reactor shutdown up to that time. By correcting this change, The subsequent water level can be estimated. In this case, the initial inventory change for the representative event is evaluated in advance by analysis or the like, and stored in the memory of the reactor pressure vessel water level estimating apparatus 20, and the value for the corresponding event is extracted. It can be used for correction.

  FIG. 4 is a block diagram showing a configuration of the water injection state quantity determination unit 23 of the reactor pressure vessel water level estimation device 20. The water injection state quantity determination unit 23 associates the value of the compressed water density ρin with the value of the compressed water density ρin with respect to the value of the temperature Tin of the compressed water, and the value of the enthalpy Hin of the compressed water with respect to the temperature value. It has a compressed water enthalpy table 23b.

  Since the influence of the pressure on the compressed water is small, for example, the density and the enthalpy of the compressed water in the case of the pressure value on the outlet side of a pump (not shown) for pumping the cooling water in the water injection pipe 7 may be different. Is not big. Upon receiving a temperature signal from the thermometer 9 provided in the water injection pipe 7, the water injection state quantity determination unit 23 cools the inside of the water injection pipe 7 with respect to the water injection temperature Tin based on the compressed water density table 23a. The density ρin of the water is determined, and the enthalpy Hin of the cooling water flowing inside the water injection pipe 7 is determined based on the compressed water enthalpy table 23b.

The water injection flow rate determination unit 24 receives the flow signal from the flow meter 8 provided for measuring the flow rate in the water injection pipe 7, and converts the water injection volume flow rate Gin into the water injection mass flow rate Win as in the following equation (1). Convert. The conversion to the water injection mass flow rate Win uses the water density ρin determined by the water injection state quantity determination unit 23.
Win = ρin · Gin (1)

  FIG. 5 is a block diagram showing the configuration of the saturated state quantity determination unit 25 of the reactor pressure vessel water level estimation device 20. The saturated state quantity determination unit 25 has a saturated water density table 25a, a saturated water enthalpy table 25b, and a saturated water evaporation latent heat table 25c.

  The saturated water density table 25a associates the saturated water density ρs with the saturation pressure Ps. The saturated water enthalpy table 25b associates the saturated water enthalpy Hf with the saturated pressure Ps. Further, the saturated water evaporation latent heat table 25c associates the evaporation latent heat Hfg with the saturation pressure Ps.

  FIG. 6 is a block diagram showing the contents of the steam generation amount calculation unit 27 and the water level determination unit 28 of the reactor pressure vessel water level estimation device 20.

  The steam generation amount calculation unit 27 includes the decay heat Q from the decay heat determination unit 22, the density ρin and enthalpy Hin of water injection from the water injection state amount determination unit 23, the water injection mass flow rate Win from the water injection flow rate determination unit 24, and the saturated state. The density ρs of saturated water, the enthalpy of saturated water Hf, and the latent heat of vaporization Hfg from the amount determination unit 25 are received as inputs.

Using these inputs, the steam generation amount calculation unit 27 calculates the steam generation amount Wg based on the following equation (2).
Wg = [Q-Win (Hf-Hin)] / Hfg (2)

  Equation (2) is an equation assuming a model in which the cooling water held in the reactor pressure vessel 2 sequentially and completely mixes with the incoming water injection. Strictly speaking, the inside of the reactor pressure vessel 2 is in a subcooled state near the flow of the injected water, and the complete mixing is a virtual state. However, first of all, it is important to be able to monitor changes in water level with a simple model. In addition, a simple model is used because there is a means for improving the accuracy, including performing the correction described below. Note that a two-point model of a subcool region and an evaporation region can also be used.

  The water level determination unit 28 includes a water level calculation unit 28a, a volume water level conversion table 28b, and a correction unit 28c. The volume water level conversion table 28b is a table for associating the volume occupied by water with the water level when filling the space in the reactor pressure vessel 2 with water from below. In addition, the volume may be a volume for a height higher than the assumed minimum level. Alternatively, based on the operation reference water level, the volume when the water level is lower than this water level may be set as a negative volume, and the volume when the water level is higher than this water level may be set as a positive volume.

The water level determination unit 28 receives as input the steam generation amount Wg from the steam generation amount calculation unit 27, the water injection mass flow rate Win from the water injection flow rate determination unit 24, and the saturated water density ρs from the saturation state amount determination unit 25. The water level calculator 28a calculates the amount of change of the mass M of the saturated water in the reactor pressure vessel 2 during the time Δt based on the following equations (3) and (4).
dM / dt = Win-Wg (3)
ΔM = (dM / dt) × Δt (4)

Next, the water level calculation unit 28a converts the change amount ΔM of the retained mass of the saturated water into a change amount of the retained volume by the following equation (5), adds it to the previous retained volume Vn of the saturated water, and after Δt has elapsed. Of the new saturated water Vn _{+ 1} is calculated.
V _{n + 1} = V _n + ΔM / ρs (5)

Next, the water level calculation unit 28a estimates the water level in the reactor pressure vessel 2 corresponding to the volume Vn + 1 in the reactor pressure vessel 2 by the following equation (6), that is, based on the volume water level conversion table 28b. Determine the value.
L = L (V) (6)

  As described above, the water level estimation device 20 in the reactor pressure vessel according to the present embodiment can estimate the water level in the reactor pressure vessel 2 independently of the water level measurement by the water level gauge 4.

  FIG. 7 is a diagram showing an example of a screen display of a trend display of measured values and estimated values of the reactor water level. The display device 30 displays such a trend. The estimated value is indicated by a solid line in the display of FIG. In addition, when the water level gauge 4 is sound and can transmit a water level signal, an abnormality occurs in the state of the water level gauge 4 by displaying the water level measurement value based on the signal of the water level gauge 4 as shown by a broken line. You can be sure that you do not.

  The correction unit 28 c (FIG. 6) receives the determination result of the estimated water level by the water level determination unit 28 and the trend of the measurement result of the water level meter 4 from the water level storage unit 26. The correction unit 28c performs correction when receiving a correction command from outside.

  FIG. 8 is a conceptual graph for explaining a method of correcting the estimated value based on the measured value of the reactor water level. In FIG. 8, a curve A indicated by a broken line is a measurement result of the water level meter 4 from the water level storage unit 26. A curve B indicated by a solid line is a result of determining the estimated water level by the water level determination unit 28. Now, it is assumed that there are two places where the characteristic change occurs on the curve A, that is, A1 and A2. Similarly, it is assumed that there are two places, B1 and B2, which are considered to correspond to A1 and A2 of the curve A in the places where the characteristic changes in the curve B. Such a location corresponds to a height at which the cross-sectional area in the reactor pressure vessel 2 changes suddenly.

  As shown in FIG. 8, the time and water level at each location are represented by combinations in parentheses, and A1 (tA1, LA1), A2 (tA2, LA2), B1 (tB1, LB1), B2 (tB2, LB2). ). A vector from the point A1 indicated by the two-dot chain line to the point A2 is referred to as a vector AA, and a vector from the point B1 indicated by the chain line to the point B2 is referred to as a vector BB.

  When the directions and magnitudes of the vector AA and the vector BB match, that is, when one moves parallel and overlaps the other, it is a case where the time and the water level are only shifted from each other. In this case, the curve A and the curve B will coincide if they are corrected so as to be shifted.

  If only the horizontal axis, that is, the time axis component of both vectors is different, and the horizontal axis component of the vector BB is larger than the horizontal axis component of the vector AA, the change in the estimated water level matches the tendency of the change in the actual water level. However, the change has been delayed over time. In this case, for example, while the curve of the volume water level conversion table 28b is maintained, the correction can be made by setting the horizontal axis V to a small value or the vertical axis to a large value.

  Even when only the components of the horizontal axis, that is, the time axis of the two vectors are different, the correction can be made by changing the scale of the vertical axis while maintaining the curve of the volume water level conversion table 28b, for example.

  In the case of a combination of the above cases, correction can be made by combining a change in scale and a shift.

  In addition, not only at the time of an accident of the reactor facility, but also at the time of normal shutdown, the water level measurement result of the water level gauge 4 and the water level estimation result by the water level estimation device 20 in the reactor pressure vessel are displayed and compared with each other. It is possible to grasp the degree of estimation accuracy of the water level estimation device 20 in the pressure vessel. Alternatively, when the deviation is large, the cause of the deviation is grasped and countermeasures are taken, whereby the estimation accuracy of the reactor pressure vessel water level estimation device 20 can be improved.

  FIG. 9 is a flowchart showing the procedure of the method for estimating the water level in the reactor pressure vessel according to the first embodiment. First, after the signal indicating that the reactor has stopped is started, the following steps are repeated at time intervals of Δt until the termination is determined.

  First, the decay heat determination unit 22 starts time counting (step S01), and determines the decay heat at that time point t (step S02). Next, based on the signal of the water temperature Tin from the thermometer 9, the water injection state quantity determining unit 23 determines the density ρin of the water injection and the enthalpy Hin of the water injection (Step S03). Next, the water injection flow rate determining unit 24 determines the water injection mass flow rate Win based on the measured value of the water injection volume flow rate Gin (step S04). Further, based on the saturation pressure Ps, the saturated state amount determination unit 25 determines the density ρs of the saturated water, the enthalpy of saturated water Hf, and the latent heat of evaporation Hfg (step S05).

  Here, step S04 needs to be after step S03, but the order of these, step S02, and step S05 among the three parties does not matter.

  Next, the water level calculation unit 28a of the steam generation amount calculation unit 27 calculates the steam generation amount Wg based on the decay heat Q, the water injection mass flow rate Win, the enthalpy Hin, the saturated water enthalpy Hf, and the latent heat of evaporation Hfg (step S06). ).

  Next, the water level determination unit 28 receives the steam generation amount Wg from the steam generation amount calculation unit 27, the water injection mass flow rate Win from the water injection flow rate determination unit 24, and the saturated water density ρs from the saturation state amount determination unit 25, The estimated water level is determined (Step S20).

  Specifically, first, the mass change amount ΔM in the reactor pressure vessel 2 at the time interval Δt is calculated based on the water injection mass flow rate Win and the steam generation amount Wg (step S07). Based on this, the volume V of the water in the reactor pressure vessel 2 is calculated (step S08), and the estimated value of the water level L in the reactor pressure vessel 2 is determined from the volume V using a volume level conversion table (step S08). Step S09).

  Thereafter, an end determination is made (step S10), and if not end (NO in step S10), step S02 is started at the timing of t + Δt from the point where the previous time was t, and steps S02 and thereafter are repeated. If it is determined that the processing is to be ended (YES in step S10), the processing ends. It should be noted that the time interval Δt may be gradually set to a long time interval since the change in the event becomes gradual as the time elapses after the reactor shutdown.

  Thus, according to the method for estimating the water level in the reactor pressure vessel according to the present embodiment, the water level in the reactor pressure vessel 2 can be estimated independently of the water level measurement by the water level gauge 4.

  As described above, the reactor pressure vessel water level estimation device 20 and the reactor pressure vessel water level estimation method according to the present embodiment can reduce the load on the operator while reducing the load on the operator even during an accident at the reactor facility. Monitoring of the reactor water level becomes possible.

[Second embodiment]
FIG. 10 is a block diagram illustrating a configuration of a reactor pressure vessel water level estimation device according to the second embodiment. This embodiment is a modification of the first embodiment. The second embodiment is a case where the amount of leakage from the reactor pressure vessel 2 can be grasped for some reason. A case where the amount of leakage can be grasped is, for example, a case where the level of the cooling water leaked to a specific location such as a sump pit and accumulated at that location can be grasped. Alternatively, it is a case where the gas leaks out of the system via a pipe having a flow meter.

In this case, when the leakage amount per unit time is W _L, the water level calculation section 28a of the water level determination unit 28, instead of the equation (3) of the first embodiment, calculates a ΔM by the following equation (7) I do.
dM / dt = (Win−Wg−W _L ) / ρs (7)
As a result, the estimation accuracy is further improved.

[Third Embodiment]
FIG. 11 is a block diagram showing the configuration of the reactor pressure vessel water level estimation device according to the third embodiment. This embodiment is a modification of the first embodiment. The third embodiment is a case where the accuracy of the water level estimating device 20 in the reactor pressure vessel can be secured to some extent, and a case where the water level gauge 4 is sound. The water level estimation device 20 in the reactor pressure vessel according to the present embodiment further includes a leak amount estimation unit 29.

  In this case, the measurement result by the water level gauge 4 always becomes higher than the estimation result of the transition by the water level estimation device 20 in the reactor pressure vessel. Therefore, the leakage amount estimation unit 29 can grasp the transition of the leakage amount by calculating this difference as the leakage amount.

[Other Embodiments]
Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. For example, in the case of the same light water-cooled reactor such as a pressurized water reactor (PWR), the water level can be basically estimated by the same device or method as in the embodiment. However, in the PWR, since the water level is measured at the pressurizer, the calibration part may not be applicable.

  Further, the features of each embodiment may be combined. Further, these embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Core, 2 ... Reactor pressure vessel, 3 ... Reactor containment vessel, 4 ... Water level gauge, 4a ... Condenser tank, 5 ... Coolant, 5a ... Liquid phase part, 5b ... Gas phase part, 5c ... Liquid level, 6: Pressure gauge, 7: Water injection pipe, 8: Flow meter, 8a: Flow rate measuring element, 9: Thermometer, 10: Steam pipe, 20: Water level estimating device in reactor pressure vessel, 22: Decay heat determining unit, 22a ... Clock, 22b ... Decay heat table, 23 ... Water injection state quantity determination unit, 23a ... Compressed water density table, 23b ... Compressed water enthalpy table, 24 ... Water injection flow rate determination unit, 25 ... Saturation state amount determination unit, 25a ... Saturated water Density table, 25b: saturated water enthalpy table, 25c: saturated water evaporation latent heat table, 26: water level storage unit, 27: steam generation amount calculation unit, 28: water level determination unit, 28a: water level calculation unit, 28b: volume water level conversion table , 28c... Correction unit, 2 ... leakage amount estimating unit, 30 ... display unit

Claims (6)

A pressure measurement value provided by a pressure gauge provided in a reactor pressure vessel in which water is injected and steam is generated by containing a reactor core, a temperature measurement value provided by a thermometer provided in a water supply pipe for guiding the water supply, and a volume flow rate provided by a flow meter Based on the output of each measurement value, a reactor pressure vessel water level estimating device for estimating a temporal change of the water level of the cooling water of the reactor pressure vessel,
A decay heat determining unit that determines a decay heat Q generated from the core for a time after receiving the reactor stop system operation signal;
A water injection state quantity determining unit that determines the density ρin and the enthalpy Hin of the water injection based on the measured value of the temperature of the water injection,
A water injection flow rate determining unit for determining the injection mass flow Win based on the density ρin and volume flow measurements Gin of the water injection,
A saturated state determining unit that determines a saturated water enthalpy Hf, a saturated water density ρs, and a latent heat of vaporization Hfg of the retained water in a liquid phase in the reactor pressure vessel based on the measurement value of the pressure gauge;
Wherein the decay heat Q, the an injection mass flow Win, and the enthalpy Hin, the steam generation amount calculating unit that calculates the saturated water enthalpy Hf and the latent heat of vaporization Hfg Toka et steam generation amount Wg,
A water level determination unit that determines an estimated water level in the reactor pressure vessel based on the water injection mass flow rate Win, the steam generation amount Wg, and the saturated water density ρs,
An apparatus for estimating a water level in a reactor pressure vessel, comprising:
The steam generation amount calculating unit, a reactor pressure vessel water level estimation apparatus according to pre Ki蒸 gas generation amount Wg to claim 1, characterized in that calculated by the following equation.
Wg = [Q-Win (Hf-Hin)] / Hfg   When the water level gauge for measuring the water level in the reactor pressure vessel is sound, a correction unit that corrects the estimated water level based on a difference between a temporal change of the water level and a temporal change of the estimated water level by the water level meter. The apparatus for estimating a water level in a reactor pressure vessel according to claim 1 or 2, further comprising:   When the water level gauge that measures the water level in the reactor pressure vessel is healthy, the amount of leakage of the cooling water from the reactor pressure vessel is estimated based on the difference between the water level measured by the water level gauge and the estimated water level. 4. The apparatus for estimating a water level in a reactor pressure vessel according to claim 1, further comprising a leak amount estimating unit that leaks. A pressure measurement value provided by a pressure gauge provided in a reactor pressure vessel in which water is injected and steam is generated by containing a reactor core, a temperature measurement value provided by a thermometer provided in a water supply pipe for guiding the water supply, and a volume flow rate provided by a flow meter. A method of estimating a water level in a reactor pressure vessel for estimating a temporal change in a water level of the cooling water in the reactor pressure vessel based on the output of each measurement value,
A decay heat determination unit that determines a decay heat Q generated from the core for a time after receiving the reactor shutdown system operation signal;
Water injection state quantity determination unit, wherein determining the density ρin and enthalpy Hin water injection based on the measured value of the temperature of the water injection, water injection flow rate decision unit, based on the density ρin and the injection of the volume flow measurement Gin A water injection state quantity determining step of determining a water injection mass flow rate Win;
A saturated state quantity determining unit that determines a saturated water enthalpy Hf, a saturated water density ρs, and a latent heat of vaporization Hfg of the retained water in a liquid phase in the reactor pressure vessel based on the measurement value of the pressure gauge. Steps and
Steam generation amount calculating unit, wherein the decay heat Q, the an injection mass flow Win, and the enthalpy Hin, steam generation amount calculating step of calculating the saturated water enthalpy Hf and the latent heat of vaporization Hfg Toka et steam generation amount Wg When,
A water level determining step of determining an estimated water level in the reactor pressure vessel based on the water injection mass flow rate Win, the steam generation amount Wg, and the saturated water density ρs,
A method for estimating a water level in a reactor pressure vessel, comprising:
The water level determination step,
A mass change amount calculating step of calculating the mass change amount ΔM in the reactor pressure vessel at predetermined time intervals based on the water injection mass flow rate Win and the steam generation amount Wg,
A volume calculating step in which the water level determining unit calculates a volume V of water in the reactor pressure vessel based on the mass change amount ΔM and the saturated water density ρs;
An estimated water level determination step of determining the estimated value of the water level in the reactor pressure vessel from the volume V using a volume water level conversion table,
The method for estimating a water level in a reactor pressure vessel according to claim 5, wherein:

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