JP2011038818A - Nuclear reactor control support system and nuclear reactor control support method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nuclear reactor control support system which reduces the dosage rate of radioactivity in a work area around a nuclear reactor to a target value, without fail, and performs cooling as rapidly as possible, while taking into account the influence of the state of facilities and the operation situation of the nuclear reactor. <P>SOLUTION: The nuclear reactor control support system 200 is constituted of: an input unit 220 for inputting a target atmosphere dosage rate; a memory unit 230 for storing correlation data 232 of the dosage rate-radioactivity amount and correlation data 234 of the radioactivity variation amount-temperature reduction rate; a carry-in amount acquisition unit 240 for acquiring the amount of clad; a calculation unit 250 for calculating the temperature reduction rate; and an output unit 260 for outputting the temperature reduction rate, wherein the calculation unit calculates the radioactivity amount from the target atmosphere dosage rate and the correlation data of the dosage rate-radioactivity amount, calculates the variation amount from the radioactivity amount and the clad amount, and calculates the temperature reduction rate from the variation amount and the correlation data of the radioactivity variation amount-temperature reduction rate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a nuclear reactor control support system and a nuclear reactor control support method for setting a temperature drop rate of nuclear reactor water when the operation of a nuclear power plant nuclear reactor is stopped.

  At nuclear power plants, apart from daily maintenance inspections, large-scale inspections are regularly conducted. Specifically, under the current laws and regulations, the operation of the power plant is stopped once every 13 to 24 months, and inspections are performed all at once during the stop period. In such inspections, workers also enter and exit the reactor containment vessel in which the reactor is stored. Therefore, in order to reduce the amount of radiation exposure of workers and ensure safety, radiation in the atmosphere inside the reactor containment vessel The dose rate should be as low as possible.

  By the way, the above-described nuclear reactors are mainly classified into a pressurized water reactor (PWR) and a boiling water reactor (BWR). A pressurized water reactor heats pressurized water to a high temperature (about 300 ° C. or higher) using thermal energy generated by a fission reaction, and gives the heat of the pressurized water to water in a steam generator. Then, the turbine generator is turned using steam generated by boiling the water to generate electric power. In a boiling water reactor, water (reactor water) is boiled using thermal energy generated by a fission reaction, and a turbine generator is turned using steam generated thereby to generate electric power. In addition to these nuclear reactors, an advanced boiling water reactor (ABWR), which is an improvement of the boiling water reactor, has been introduced in recent years. Improvements are being made.

  Among the reactors described above, in boiling water reactors and improved boiling water reactors, the reactor water is used as steam to generate power in a turbine generator, and then in a condenser. It is cooled and supplied to the reactor again. Therefore, the reactor water circulates through the nuclear reactor, the turbine generator, the condenser, and the piping connecting them. Among the facilities in which the reactor water circulates, particularly in condensers and pipes, metal impurities (hereinafter referred to as cladding) are generated due to aging, damage, corrosion, etc. of the members constituting them.

  The generated clad is brought into the reactor by circulation of the reactor water, and adheres to the surface of the nuclear fuel (fuel rod) in the reactor. Then, the cladding is activated upon irradiation with neutrons generated during the burning of nuclear fuel, and becomes a radioactive material. When the activated clad peels off from the nuclear fuel, it enters the reactor water, circulates along the piping installed in the reactor containment vessel together with the reactor water, and emits radiation into the reactor containment vessel.

  Conventionally, it is known that the dose rate in the reactor containment vessel increases when the reactor water temperature is lowered when the reactor is shut down. This is considered to be because the clad peels off from the fuel rod when the temperature decreases due to the difference in thermal expansion coefficient between the fuel rod and the clad. For example, Patent Document 1 discloses a method for shutting down a boiling water reactor plant as a method for suppressing such an increase in dose rate when the reactor is shut down. In such a method, in the process of lowering the reactor water temperature, the reactor water temperature is maintained for a predetermined time when the reactor water temperature reaches 100 ° C. to 150 ° C. at which the elution rate of metal ions increases, thereby removing radioactivity. According to this, it is said that the radiation dose rate of piping and the like can be reduced by removing radioactivity from the piping and the like without requiring a large-scale additional facility during the stop operation of the plant.

  Further, as described in Patent Document 1, as the reactor water temperature is rapidly decreased in the operation of shutting down the reactor, more clad adhered to the surface of the fuel rod is peeled off, and the radioactive contamination of the reactor water proceeds. It has been known for a long time. That is, the amount of clad separation from the surface of the fuel rod increases or decreases depending on the reactor water temperature drop rate at the time of shutting down the reactor, and this increases or decreases to the radiation dose rate at the work place in the reactor containment vessel. Was revealed. Therefore, it is recommended that the temperature drop rate of reactor water at the time of reactor shutdown be 15 ° C / h or less. At present, a predetermined temperature drop rate is set with reference to this value, and the reactor shutdown The operation is being performed.

JP-A-5-164890

  However, in the reactor shutdown method described in Patent Document 1, it can be seen that the elution amount of metal ions is maximum when the reactor water temperature is in the range of 100 ° C to 150 ° C. It is not clear whether it is reduced to some extent. Therefore, even if the stopping method described in Patent Document 1 is actually used, it is difficult to determine how much effect can be obtained.

  Further, even if the amount of clad peeling from the surface of the fuel rod changes due to the reactor water temperature drop rate, if the amount of clad brought into the reactor by the circulation of the reactor water (hereinafter referred to as the carry-in amount) is different, The amount of radioactive material should also be different. In other words, if the amount of clad brought in is large, the amount of clad that is peeled off when the reactor is shut down also increases the radiation dose rate in the reactor containment vessel. Conversely, if the amount of clad is small, The radiation dose rate in the reactor containment vessel is reduced. The amount of cladding is not always a constant amount because it is affected by the state of the reactor equipment and the operating conditions.

  Therefore, even if a predetermined temperature drop rate is set low (15 ° C./h or less, etc.) and the stop operation is performed as in the past, it is difficult to reduce the dose rate. For this reason, even if such a shutdown operation is performed, the radiation dose rate in the reactor containment vessel does not necessarily reach the target value.

  Moreover, lowering the temperature drop rate means that cooling takes time. Since the reactor water at the time of operation is as high as about 300 ° C., the lower the temperature drop rate, the longer it takes to stop the plant cold, and there is a possibility of causing a delay that cannot be ignored in the inspection process. And even if the temperature drop rate is kept low at a certain value, the dose rate may certainly decrease, but the temperature drop rate may be lowered more than necessary, and there is a possibility that it takes time to waste. is there. Therefore, as long as the dose rate can be suppressed to the target value, there is a demand for setting the temperature drop rate as high as possible (cooling quickly).

  In view of such problems, the present invention can reliably reduce the radiation dose rate of the work area around the reactor to a target value while taking into account the influence of the state of the reactor equipment and the operation status. An object of the present invention is to provide a reactor control support system and a reactor control support method that perform cooling as quickly as possible.

  In order to solve the above problems, the inventors have intensively studied the dependence of various data, and found that the dose rate in the workplace is correlated with the amount of radioactivity in the reactor, and the amount of change in radioactivity is the temperature drop rate. And the temperature drop rate was found from the amount of change in radioactivity and the amount brought in, and the present invention was completed by further investigation.

  That is, a typical configuration of the reactor control support system according to the present invention is a reactor control support system that determines the temperature drop rate of reactor water when the operation of a nuclear power plant reactor is stopped. , Dose rate-radioactivity correlation data that stores the correlation between the dose rate and the amount of radioactivity in the reactor, and the input unit for inputting the target atmosphere dose rate, which is the target value of the radiation dose rate in the atmosphere around the reactor And a storage unit that stores the correlation between the amount of change in radioactivity and the temperature drop rate, and the correlation between the change in radioactivity and the temperature drop rate, and the data was brought into the reactor during one cycle of the reactor A carry-in amount acquisition unit that acquires the amount of cladding, a calculation unit that calculates a temperature drop rate, and an output unit that outputs the calculated temperature drop rate, the calculation unit includes a target ambient dose rate and a dose rate -From radioactivity correlation data Calculate the amount of radioactivity, calculate the amount of change in radioactivity from the calculated amount of radioactivity and the amount of cladding, and calculate the rate of temperature drop from the calculated amount of change in radioactivity and the amount of change in radioactivity-temperature drop rate correlation data Is calculated.

  According to the above configuration, when the target atmospheric dose rate is input, the calculation unit refers to the dose rate-radioactivity amount correlation data and the radioactivity change amount-temperature drop rate correlation data stored in the storage unit, and brings them in. The temperature drop rate corresponding to the target atmospheric dose rate is calculated using the clad amount acquired from the amount acquisition unit. Therefore, by performing the reactor shutdown operation based on the calculated temperature drop rate, it is possible to reliably reduce the radiation dose rate of the work area around the reactor to the target value, and quickly The furnace can be cooled. Further, since the amount of cladding is used for calculating the temperature drop rate, the influence of the state of the reactor equipment and the operation status can be reflected in the calculation of the temperature drop rate.

  The dose rate-radioactivity correlation data may be correlation data for each area based on the radioactivity measured for each area around the reactor and the radiation dose rate.

  The dose rate of radioactivity in the atmosphere around the reactor varies from area to area depending on the presence or absence of the piping through which the reactor water circulates. Therefore, by making the dose rate-activity level correlation data the correlation data actually measured for each area as in the above-described configuration, it is possible to reflect the influence of such an arrangement or the like on the dose rate-activity level correlation data. This makes it possible to improve the accuracy of the dose rate-activity level correlation data.

  The above radioactivity change-temperature drop rate correlation data is divided into a plurality of measured radioactivity change rates and temperature drop rates into two or more in a predetermined temperature range, and the radioactivity for each of the divided temperature ranges. It is preferable that this is an approximate function in the average value when the average value of the change amount and the temperature drop rate is obtained.

  As in this configuration, the measured amount of change in radioactivity and the temperature drop rate are divided into two or more in a predetermined temperature range, and the average value is obtained to obtain one value for each division. Can do. Therefore, even if there is a significant difference in the number of data actually measured for each temperature range (number of samples), the influence on the radioactivity change amount-temperature drop rate correlation data due to such difference can be eliminated. Moreover, the versatility of data can be improved by making radioactivity change-temperature drop rate correlation data into the approximate function in the average value.

  In order to solve the above problems, a typical configuration of a nuclear reactor control support method according to the present invention is an atomic unit that determines a temperature drop rate of reactor water when a nuclear power plant reactor is shut down. This is a reactor control support method that inputs the target atmospheric dose rate, which is the target value of the radiation dose rate in the atmosphere around the reactor, and obtains the amount of cladding brought into the reactor during one cycle of the reactor. Calculate the radioactivity from the target atmosphere dose rate and the dose rate-radioactivity correlation data that stores the correlation between the dose rate and the radioactivity in the reactor, and radiate from the calculated radioactivity and the clad amount. The amount of change in activity is calculated, and the rate of temperature drop is calculated from the calculated amount of change in radioactivity and the correlation between the amount of change in radioactivity and the rate of temperature drop. It is characterized by calculating.

  The component corresponding to the technical idea in the reactor control support system described above and the description thereof can be applied to the reactor control support method.

  According to the present invention, it is possible to reliably reduce the dose rate of the radioactivity in the work area around the reactor to a target value while taking into consideration the influence of the state of the reactor equipment and the operation status, and as much as possible. A reactor control support system and a reactor control support method that perform rapid cooling can be provided.

It is a figure which shows the structural example of a nuclear power plant. It is a block diagram which shows the structure of the nuclear reactor control assistance system concerning this embodiment. It is a figure which shows dose rate-radioactivity amount correlation data and activity change amount-temperature drop rate correlation data. It is a flowchart explaining the outline of the temperature fall rate calculation procedure of the assistance system concerning this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Nuclear power plant)
FIG. 1 is a diagram illustrating a configuration example of a nuclear power plant. In addition, the nuclear power plant also includes a control rod drive system, a reactor isolation cooling system, a residual heat removal system, a high pressure core water injection system, a fuel pool purification system, a reactor coolant purification system, and a boric acid water injection system. However, in order to facilitate understanding, illustration and description thereof are omitted in the present embodiment.

  As shown in FIG. 1, the nuclear power plant 100 includes a nuclear reactor 110, a nuclear reactor containment vessel 120, a steam pipe 130, a condensate water supply pipe 132, a turbine 134, a generator 136, and a condenser 138. And a seawater pipe 140.

  The nuclear reactor 110 is a boiling water nuclear reactor in this embodiment, and fissions a fuel rod 112 made of uranium or the like to generate a large amount of heat (thermal energy). Condensate and feed water (reactor water) supplied from the condensate water supply pipe 132 are transferred to the reactor 110 and become high-temperature and high-pressure steam of about 280 to 300 ° C. and 70 to 80 atm by heat generated in the reactor 110. It is sent to the turbine 134 via the steam pipe 130.

  The turbine 134 is a machine that converts thermal energy of steam carried by the steam pipe 130 into power. The steam generated in the nuclear reactor 110 collides with the blades constituting the turbine 134 and creates a rotational force. The turbine 134 is coaxially connected to the generator 136, and the rotation of the turbine 134 is directly transmitted to the generator 136 to generate electricity. Electricity generated by the generator 136 is transmitted to a transformer (not shown) and supplied as electric power to various places.

  The condenser 138 collects and cools the steam that has rotated the turbine 134, returns it to water, and sends it again to the reactor 110 through the condensate water supply pipe 132. In the condenser 138, seawater is constantly circulating through the seawater piping 140, and the water vapor is rapidly cooled and liquefied. At this time, since the volume of the water vapor rapidly decreases, the pressure decreases, the circulation of the water vapor near the turbine 134 is improved, and the rotation of the turbine 134 can be increased.

  The reactor 110 is stored in the reactor containment vessel 120. In the present embodiment, the reactor containment vessel 120 has a plurality of areas (1 floor underground, 6 floors above ground, a total of 7 floors) as indicated by broken lines. ). The number of floors is an example, and the present invention is not limited to this. In this embodiment, a boiling water reactor is illustrated as the reactor 110. However, a reactor control support system, which will be described later, can also be applied to an improved boiling water reactor.

  In the nuclear power plant 100 described above, the operation of the nuclear reactor 110 is stopped at predetermined intervals, and simultaneous inspection is performed during the stop period. Hereinafter, the details of the reactor control support system that determines the temperature drop rate of the reactor water when the operation of the reactor 110 is stopped will be described.

  FIG. 2 is a block diagram showing the configuration of the reactor control support system according to the present embodiment. As shown in FIG. 2, the reactor control support system according to the present embodiment (hereinafter simply referred to as “support system 200”) includes a control unit 210, an input unit 220, a storage unit 230, and a carry-in amount. The acquisition part 240, the calculating part 250, and the output part 260 are provided.

  The control unit 210 manages and controls functions of the entire support system 200 using a semiconductor integrated circuit including a central processing unit (CPU).

  The calculation unit 250 calculates a temperature drop rate according to the target atmospheric dose rate input to the input unit 220. As will be described in detail later, the calculation unit 250 calculates a radioactivity amount from the target atmospheric dose rate and the dose rate-activity amount correlation data, calculates a change amount from the calculated activity amount and the clad amount, The temperature drop rate is calculated from the calculated change amount and the radioactivity change amount-temperature drop rate correlation data.

  The input unit 220 allows the user of the support system 200 to input information. In the present embodiment, a target atmosphere dose rate that is a target value of the radiation dose rate in the atmosphere around the reactor 110 (in the reactor containment vessel 120) is input to the input unit 220. As the input unit 220, a keyboard or a pointing device such as a mouse can be preferably used. Information may be input from a remote client computer (not shown) via a network such as the Internet. In this case, the network interface corresponds to the input unit 220.

  The storage unit 230 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores programs, data, and the like that are processed by the control unit 210. In the present embodiment, the storage unit 230 stores dose rate-activity level correlation data 232 and activity change-temperature drop rate correlation data 234.

  FIG. 3 is a diagram showing dose rate-activity amount correlation data 232 and activity change amount-temperature drop rate correlation data 234. In particular, FIG. 3A is a diagram showing dose rate-radioactivity amount correlation data 232, and FIG. 3B is a diagram showing radioactivity change amount-temperature drop rate correlation data 234.

  The dose rate-radioactivity amount correlation data 232 is data in which the correlation between the dose rate and the radioactivity amount in the reactor 110 is stored. As a result, the calculation unit 250 refers to the dose rate-activity level correlation data 232 and sets the target radiation dose rate in the atmosphere around the reactor 110 based on the target atmosphere dose rate input to the input unit 220. It is possible to calculate the value of the radioactivity for obtaining the atmospheric dose rate.

The dose rate-radioactivity correlation data 232 in this embodiment is correlation data for each area based on the radioactivity measured for each area around the reactor (see FIG. 1) and the radiation dose rate. The dose rate is a value measured after shutting down the reactor using a dose rate meter. The amount of radioactivity is a value obtained by periodically collecting reactor water during the shutdown operation, measuring the concentration of radioactive material with a Ge semiconductor spectrometer, and multiplying by the amount of reactor water. As for the dose rate, any radioactive substance that can be generated such as Co ⁶⁰ , Mn ⁵⁴ , and Fe ⁵⁹ can be used as a measurement target, but typically Co ⁶⁰ can be used as a measurement target.

  As described above, the reactor containment vessel 120 is divided into a plurality of areas (floors), and the dose rate of radioactivity differs depending on the area depending on the presence or absence of arrangement of piping through which the reactor water circulates. When the measured radioactivity and the radiation dose rate are plotted for each area, the dose rate-radioactivity correlation data 232 is as shown in FIG. Thereby, the influence by arrangement | positioning etc. of piping can be reflected in dose rate-radioactivity amount correlation data, and it becomes possible to improve the precision of dose rate-radioactivity amount correlation data.

  In FIG. 3A, the graph is shown as a graph for visualization. However, the dose rate-activity level correlation data 232 may actually be a data array, or a functional expression obtained by approximating this. It may be. If the dose rate-radioactivity correlation data 232 is not a functional expression but a data array, the radioactivity obtained by interpolation or extrapolation (proportional distribution) with reference to data before and after the given target atmospheric dose rate Can be calculated.

  Further, in the present embodiment, the target atmosphere dose rate can be set for each area by providing the correlation data between the dose rate and the radioactivity amount for each area. However, correlation data may be recorded only for the area with the highest dose rate, and calculation may be performed on this.

  Referring to FIG. 3 (a) again, it can be seen that the dose rate (mSv / h) with respect to the amount of radioactivity suddenly increases when the amount of radioactivity exceeds 1.0E + 11 (Bq). This is presumably because the amount of clad produced by rapid cooling of the reactor water exceeds the ability of the filter to remove the cladding from the reactor water. Therefore, it is preferable that the target atmosphere dose rate is set to be less than or equal to the inflection point in the dose rate-activity level correlation data 232 as a reference.

  The radioactivity change-temperature drop rate correlation data 234 is data that stores the correlation between the radioactivity change rate and the temperature drop rate. The amount of change in radioactivity is a value obtained by dividing the amount of radioactivity by the amount of clad brought into the reactor water. Thereby, the calculation unit 250 uses the change amount calculated from the clad amount and the radioactivity amount acquired by the carry-in amount acquisition unit 240 described later, and refers to the radioactivity change amount-temperature drop rate correlation data 234. It is possible to calculate the temperature drop rate according to the target atmospheric dose rate.

  In other words, although it has been known that radiation will decrease if the temperature drop rate is reduced, there is no correlation between them in the measured values, and vague qualitative trends are only known. It was. However, the inventors were able to find that there is a high correlation between the temperature drop rate when the amount of radioactivity is divided by the amount brought in to obtain the rate of change of the amount of radioactivity. Since the carry-in amount varies depending on the plant and the operation cycle, the system described in the present invention has general versatility by giving the carry-in amount as one parameter.

  Furthermore, as shown in FIG. 3B, the radioactivity change amount-temperature drop rate correlation data 234 in the present embodiment is obtained by measuring a plurality of measured radioactivity changes and temperature drop rates in a predetermined temperature range. It is an approximate function in the average value when the average value of the activity change amount and the temperature drop rate is obtained for each of the divided temperature ranges.

  For example, in FIG. 3 (b), the temperature range is divided into four of 12 to 16 ° C, 18 to 22 ° C, 23 to 25 ° C, and 26 to 28 ° C. An average value of the rate is obtained for each divided temperature range, and an approximate function is obtained using the average value. Thus, even if there is a significant difference in the number of actually measured data for each temperature range, the measured amount of change in radioactivity and the temperature drop rate are set to one value for each category. The influence on the radioactivity change amount-temperature drop rate correlation data 234 due to the difference can be eliminated. Moreover, it is possible to improve the versatility of the data by using the radioactivity change-temperature drop rate correlation data 234 as an approximate function in the average value.

  However, instead of taking the average for each temperature range as described above, correlation data may be obtained simply from a sample of the amount of change in radioactivity and the rate of temperature drop. In this case, the radioactivity change-temperature drop rate correlation data 234 may be a data array, or may be a function equation obtained by approximating this by, for example, the least square method. If the radioactivity change-temperature drop rate correlation data 234 is not a function expression but a data array, refer to the data before and after the given radioactivity change, and perform interpolation or extrapolation (proportional distribution). Can be used to calculate the temperature drop rate.

  The carry-in amount acquisition unit 240 acquires the amount of clad brought into the reactor during one cycle of the reactor. The amount of clad brought in in one cycle is calculated periodically by measuring the clad contained in the water supply periodically using a particle counter such as a fluorescent X-ray analyzer, and multiplying the flow rate of the water supply every time it is measured, This can be obtained by integrating over one cycle. Thus, the calculation unit 250 can calculate the amount of change in radioactivity using the amount of clad (carry-in amount). Further, the amount of cladding is used for calculation of the temperature drop rate in the calculation unit 250, so that the influence of the state of the reactor equipment and the operation state can be reflected in the calculation of the temperature drop rate.

  The output unit 260 outputs the temperature drop rate calculated by the calculation unit 250. As the output unit 260, a monitor, a printer, or the like can be preferably used. Further, when accessing the support system 200 from a remote place via a network, an operation screen and information can be displayed using a web page.

  Next, a temperature drop rate calculation procedure using the support system 200 according to the present embodiment, that is, a reactor control support method will be described. FIG. 4 is a flowchart for explaining the outline of the temperature drop rate calculation procedure of the support system 200 according to the present embodiment. As shown in FIG. 4, in the temperature drop rate calculation procedure by the support system 200, the input unit 220 first receives an input of the target atmospheric dose rate of the support system 200 user (S302).

  When the target atmospheric dose rate is input, the carry-in amount acquisition unit 240 acquires the amount of clad brought into the nuclear reactor during one cycle of the nuclear reactor (S304). Next, the calculation unit 250 calculates the amount of radioactivity using the target atmospheric dose rate input to the input unit 220 and referring to the dose rate-activity level correlation data 232 stored in the storage unit 230 (S306). ). Subsequently, the calculating unit 250 calculates the amount of change in radioactivity (target amount of change in radioactivity) using the calculated amount of radioactivity and the amount of cladding acquired by the carry-in amount acquiring unit 240 (S308).

  Then, the calculation unit 250 uses the calculated change amount and refers to the radioactivity change amount-temperature drop rate correlation data 234 stored in the storage unit 230 to obtain the target atmospheric dose rate input to the input unit 220. A corresponding temperature drop rate (target temperature drop rate) is calculated (S310). When the temperature drop rate is calculated, the output unit outputs the value by, for example, displaying on a monitor (S312).

  As described above, according to the nuclear reactor control support system according to the present embodiment, the calculation unit can calculate the temperature drop rate based on the target atmospheric dose rate input to the input unit. As a result, the reactor shutdown operation is performed based on the calculated temperature drop rate, so that the radiation dose rate in the work area around the reactor is reliably reduced to the target value, and the reactor Cooling can be performed. In addition, since the amount of cladding is used for calculating the temperature drop rate, the influence of the state of the reactor equipment and the operating conditions can be reflected in the calculation of the temperature drop rate.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used as a reactor control support system and a reactor control support method for setting the temperature drop rate of reactor water when the operation of a nuclear power plant reactor is stopped.

DESCRIPTION OF SYMBOLS 100 ... Nuclear power plant, 110 ... Reactor, 112 ... Fuel rod, 120 ... Reactor containment vessel, 130 ... Steam piping, 132 ... Condensate water supply piping, 134 ... Turbine, 136 ... Generator, 138 ... Condenser, 140 ... seawater piping, 200 ... support system, 210 ... control unit, 220 ... input unit, 230 ... storage unit, 232 ... dose rate-radioactivity correlation data, 234 ... radioactivity change-temperature drop rate correlation data, 240 ... Bring-in amount acquisition unit, 250 ... calculation unit, 260 ... output unit

Claims (4)

A reactor control support system for determining a temperature drop rate of reactor water when shutting down a nuclear power plant reactor,
An input unit for inputting a target atmospheric dose rate that is a target value of a radiation dose rate in the atmosphere around the reactor;
Dose rate storing the correlation between the dose rate and the amount of radioactivity in the reactor-Radioactivity amount correlation data, and the radioactivity change amount storing the correlation between the radioactivity change amount and the temperature drop rate- A storage unit for storing temperature drop rate correlation data;
A carry-in amount obtaining unit for obtaining a clad amount brought into the nuclear reactor during one cycle of the nuclear reactor;
A calculation unit for calculating the temperature drop rate;
An output unit for outputting the calculated temperature drop rate;
With
The computing unit is
Calculate the radioactivity from the target atmosphere dose rate and the dose rate-radioactivity correlation data,
From the calculated amount of radioactivity and the amount of clad, the amount of change in the radioactivity is calculated,
A reactor control support system, wherein the temperature drop rate is calculated from the calculated change in radioactivity and the radioactivity change-temperature drop rate correlation data.   The dose rate-activity level correlation data is correlation data for each area based on the activity level measured for each area around the reactor and the dose rate of radiation. Reactor control support system when the reactor is shut down.   The radioactivity change-temperature drop rate correlation data is obtained by dividing a plurality of measured radioactivity changes and temperature drop rates into two or more in a predetermined temperature range, and the radioactivity for each of the divided temperature ranges. The reactor control support system according to claim 1, wherein the reactor control support system is an approximate function of the average value when the average value of the change amount and the temperature drop rate is obtained. A nuclear reactor control support method for determining a temperature drop rate of reactor water when shutting down a nuclear power plant reactor,
Enter the target atmospheric dose rate, which is the target value of the radiation dose rate in the atmosphere around the reactor,
Obtaining the amount of cladding brought into the reactor during one cycle of the reactor;
Calculate the radioactivity from the target atmosphere dose rate, and the dose rate-radioactivity correlation data storing the correlation between the radioactivity in the reactor and the dose rate,
From the calculated amount of radioactivity and the amount of clad, the amount of change in the radioactivity is calculated,
Calculating the temperature drop rate from the calculated change in radioactivity and the radioactivity change amount-temperature drop rate correlation data storing the correlation between the radioactivity change amount and the temperature drop rate. A featured nuclear reactor control support method.

Images