JP5025451B2 - Core monitoring device - Google Patents

Description

  The present invention relates to a core monitoring apparatus that performs criticality monitoring while a reactor is stopped, such as during fuel loading, fuel replacement, and various inspections in a nuclear reactor.

  As a device for monitoring the core state of a nuclear reactor, Patent Document 1 describes a monitoring device that calculates thermal characteristics during operation.

  Patent Document 2 describes a device for monitoring an abnormality during fuel loading.

JP 2003-172792 A JP 2006-98329 A

  The core performance monitoring device described in Patent Document 1 is a typical example of a core monitoring device that has already been put into practical use in an actual nuclear reactor, and all of these similar devices are assumed to operate in a high temperature state. The purpose is to monitor the thermal state value of the reactor in operation. Therefore, no consideration is given to criticality management of the reactor, prevention of erroneous fuel replacement, criticality warning for abnormal withdrawal, and recording of the core state when the reactor is shut down.

  The subcritical monitoring system described in Patent Document 2 monitors abnormalities when the reactor is stopped, particularly during fuel loading. In this system, only the signal from the nuclear instrumentation is taken in and the criticality is monitored only by diffusion calculation based on the fuel exchange procedure prepared in advance. This system assumes that the core state is in accordance with the work plan, and does not grasp the actual fuel position information from the fuel changer or the actual core state combined with the actual reactor water temperature. For this reason, when abnormal fuel loading deviates from the procedure, or when unexpected control rod withdrawal occurs, the evaluation is not based on an accurate core state. In addition, it is intended only for criticality monitoring during refueling, and is not subject to monitoring during other periodic inspections.

  An object of the present invention is to monitor a subcritical state in a wide range of reactor shutdown states, such as during fuel loading in a nuclear reactor, during fuel replacement, during various inspections, etc. It is to provide a core monitoring device that enables safe operation of the reactor.

  The object of the present invention is to obtain control rod position information, coolant temperature information, and fuel assembly arrangement information in the reactor core at the time of reactor shutdown periodically and when requested by an operator, Based on the actual combustion state of the assembly, the neutron effective multiplication factor of the core state is sequentially calculated by neutron diffusion calculation or transport calculation, etc., and a cold core monitoring means for evaluating subcriticality is provided, and the evaluation result is recorded. Achieved by saving.

  In particular, for grasping the fuel assembly arrangement when the reactor is shut down, the fuel assembly arrangement information in the reactor core is stored in the core monitoring device, and the fuel assembly information is acquired every time the fuel transfer information is acquired from the fuel exchange device. Based on the actual combustion state of each fuel assembly in the core, using the control rod position information and coolant temperature information acquired periodically or simultaneously with fuel movement information acquisition, the arrangement information shall be updated. A cold-temperature core monitoring means for sequentially calculating the neutron effective multiplication factor of the core state by transport calculation etc. and evaluating the subcriticality after the fuel transfer is provided, and the evaluation result is recorded and stored.

  In addition, by using the measured neutron detector signal, the fuel assembly arrangement information in the reactor core is stored in the reactor monitoring device, and the fuel assembly arrangement is obtained every time the fuel transfer information is acquired from the fuel exchange device. Neutron diffusion calculation or transport calculation based on the actual combustion state of each fuel assembly in the core using the control rod position information and coolant temperature information acquired periodically or simultaneously with fuel movement information acquisition A cold temperature core monitoring means for monitoring abnormalities during fuel transfer work is provided by calculating the count rate of the neutron detector by means of, etc., and comparing with the actual count rate from the corresponding neutron detector, Record and save.

  In addition, when there is a core state change judging means, the event trigger function (automatic start function at the time of core abnormality) activates the cold temperature core monitoring means, and when an abnormal event such as pulling out the control rod in the reactor actually occurs In addition, high-accuracy criticality assessment and record storage shall be performed automatically.

  The cold-temperature core monitoring means uses the information calculated and managed by the operating core monitoring means that monitors the core state during the operation of the reactor as the actual combustion state of each fuel assembly in the reactor core, This makes it possible to accurately evaluate the critical state of the core.

  According to the present invention, the cold core monitoring means allows the actual control rod insertion state and temperature instead of the core state based on the work plan during various operations while the reactor is shut down, periodically and at the request of the operator. Because the state and fuel assembly layout information is sequentially acquired and analyzed, sub-critical conditions in a wide range of reactor shutdowns, such as during fuel loading, refueling, and various inspections, are monitored. Can be operated safely. In the core calculation, the actual combustion state data of each fuel created by the core characteristic monitoring function during reactor operation by the operating core monitoring means is used, so accurate subcriticality considering the fuel characteristics at the time of evaluation is used. Degree evaluation is possible. Therefore, safety can be confirmed accurately.

  When monitoring by this device during fuel replacement, the fuel movement information is acquired every time the fuel is actually moved, the fuel assembly arrangement information is updated, and the core state is updated every time the fuel movement information is acquired. By sequentially calculating the effective neutron multiplication factor and evaluating the subcriticality after the fuel transfer, the subcriticality of the core state immediately after the fuel transfer can be monitored, and the core state after the next fuel transfer is also subcritical. It becomes possible to evaluate the degree in advance. As a result, in the unlikely event that the expected subcriticality is smaller than the set control value, a warning can be issued and the subsequent fuel transfer operation can be interrupted. Contributes to improved safety.

  Moreover, the sign of abnormality during the fuel change can be found by using the monitoring for comparing the measured value and the calculated value of the neutron detector count rate data together. The reason for the large difference between the measured value and the calculated value is that the core condition is different from what is planned in the work plan. The fuel arrangement before fuel change and the fuel movement data set in the fuel changer are not consistent. Some neutron detectors are not functioning properly. By discovering and warning these possibilities, it contributes to improving the safety of work at cold temperatures.

  Safety of the core state during the reactor shutdown period and the core state during the operation by automatic recording of monitoring results at these periodic and operator requests or every time fuel transfer information is acquired (each work step) It is possible to keep an accurate record of sex.

  In addition, if an event trigger function (automatic start function when the reactor core is abnormal) causes an accidental pull-out of the control rod, the system will wait for automatic start and there is no operator start request. Even so, it is possible to automatically activate the subcriticality evaluation function by the cold-temperature core monitoring means and store the criticality evaluation information of the core with high accuracy. As a result, it is possible to provide useful information even during analysis work to clarify the core characteristics in more detail after the stabilization of abnormal events, thereby contributing to safety improvement activities of nuclear power plants. is there.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a diagram showing a core monitoring apparatus according to the first embodiment of the present invention, and FIG. 2 is a diagram showing an entire system including the core monitoring apparatus.

  The core monitoring apparatus according to the present embodiment includes a control device 100. The control device 100 controls the entire operation, a core data input unit 2, a cold temperature core characteristic monitoring unit 3 (cool temperature core monitoring means). ), Fuel state database unit 4 (fuel state storage unit), fuel arrangement database unit 5, operating core characteristic evaluation unit 6, record storage database unit 7, calculation result output unit 8 (evaluation result storage unit), core simulator unit 9 (Cold temperature core monitoring means).

  The core simulator unit 9 evaluates the neutron effective multiplication factor, neutron flux distribution, and heat output distribution of the core system by three-dimensional neutron diffusion calculation.

  The operating core characteristic monitoring unit 6 acquires core state data such as coolant temperature data and control rod position data via the core data input unit 2 during the power operation of the reactor, and the core simulator unit 9 periodically The power distribution in the core is calculated and the thermal characteristics such as maximum line power density and minimum limit power ratio are evaluated and monitored. Further, since the reaction characteristics change with combustion of the fuel assembly during operation, the combustion state data represented by the burnup stored in the fuel state database unit 4 is sequentially updated.

The cold-temperature core characteristic monitoring unit 3 performs coolant temperature data (coolant coolant) as core state data via the core data input unit 2 during shutdown of the reactor periodically (for example, every hour) and at the request of an operator. Temperature information) , the control rod position data is acquired, and the fuel assembly arrangement data (fuel assembly arrangement information) updated with the latest fuel movement data from the fuel arrangement database unit 5 is acquired. Based on the coolant temperature data, control rod position data, fuel assembly arrangement data, and actual combustion state data (actual combustion state information) of each fuel assembly in the core stored in the fuel state database unit 4. Calculate the effective multiplication factor of the cold core by neutron diffusion calculation or transport calculation, etc., and periodically calculate the effective neutron multiplication of the reactor in the cold shutdown state based on the result It is determined whether or not the rate is unexpectedly critical, and if it is close to exceeding the criticality, warning information is output from the calculation result output unit 7 to the display device and the printer to evaluate and monitor the critical state ( Hereinafter, this function is called criticality evaluation monitoring function). These results are sequentially recorded and stored electronically in the record storage database unit 8.

  Here, the cold temperature core characteristic monitoring unit 3 uses the fuel updated by the operating core characteristic monitoring unit 6 for the actual combustion state data (data indicating the state of burnup of each fuel assembly) as described above. A state database 4 is used. Further, the fuel assembly arrangement data is grasped by sequentially updating the data stored in the fuel arrangement database unit 5 each time the fuel movement information is acquired from the fuel exchanger via the core data input unit 2. . The fuel movement information is provided in the form of a combination of the movement source coordinates and the movement destination coordinates in the core, and the fuel assembly arrangement data in the fuel arrangement database 5 is changed accordingly. As for the coolant temperature data and the control rod position data, the core coolant temperature data and the control rod position data detected by the coolant thermometer and the position detector installed in the core are respectively input to the core data input unit 2. The cold core characteristic monitoring unit 3 calculates the effective multiplication factor of the cold core using the latest data.

  Further, the cold temperature core characteristic monitoring unit 3 executes the criticality evaluation monitoring function for calculating the effective multiplication factor of the cold core at regular and operator requests as described above, and at the same time as acquiring the fuel movement information. Execute criticality evaluation monitoring function to calculate the effective multiplication factor of the core in the cold state by neutron diffusion calculation or transport calculation using coolant temperature data, control rod position data, fuel assembly arrangement data, actual combustion state data .

  According to the present embodiment configured as described above, it is possible to accurately monitor the subcriticality in a wide range of reactor shutdown states, including during fuel replacement.

  That is, the cold-temperature core characteristic monitoring unit 3 is not in the core state based on the work plan during the various operations while the reactor is shut down, or at the request of the operator, but the actual control rod insertion state and temperature state, Since the fuel assembly layout information is acquired and analyzed sequentially, the subcritical conditions in a wide range of reactor shutdowns, such as during fuel loading, refueling, and various inspections, are monitored and recorded. Can be operated safely. In the core calculation, the actual combustion state data of each fuel created by the operating core characteristic monitoring unit 6 during the operation of the reactor is used, so that accurate subcriticality evaluation considering the fuel characteristics at the time of evaluation can be performed. It becomes possible. Therefore, safety can be confirmed accurately.

  In addition, when monitoring by this apparatus is performed during the fuel exchange, the fuel movement information is acquired every time the fuel is actually moved, the fuel assembly arrangement information stored in the fuel arrangement database 5 is updated, and the fuel movement is performed. Each time the information is acquired, the criticality evaluation monitoring function is activated, and the neutron effective multiplication factor of the core state is sequentially calculated to evaluate the subcriticality after fuel transfer. In addition to monitoring, it is possible to pre-evaluate the subcriticality of the core state after the next fuel transfer. As a result, in the unlikely event that the expected subcriticality is smaller than the set control value, a warning can be issued and the subsequent fuel transfer operation can be interrupted. Contributes to improved safety.

  In addition, about the core state during the reactor shutdown period and the core state during the operation by the automatic recording of the monitoring results at these periodic and operator requests or every time fuel movement information is acquired (each work step) It is possible to keep an accurate record regarding safety.

<Second Embodiment>
A second embodiment of the present invention will be described with reference to FIG. In this embodiment, a coefficient rate data processing unit 10 and a comparison unit 11 are added to the first embodiment of FIG. The coefficient rate data processing unit 10 acquires the count rate data of SRNM, which is a neutron detector, via the core data input unit 2, and calculates the actual coefficient rate value. On the other hand, the cold-temperature core characteristic monitoring unit 3 calculates the count rate of the neutron detector using the core simulator unit 9 and compares them with the comparison unit 11. Here, as in the case of calculating the effective multiplication factor described in the first embodiment, the cold-temperature core characteristic monitoring unit 3 periodically and at the request of an operator or whenever fuel movement information is acquired (work step) Each), using the control rod position data, coolant temperature data, and fuel assembly arrangement data obtained sequentially, based on the fuel state (actual combustion state) managed by the fuel state database unit 4 or The counting rate of the neutron detector is calculated by carrying out transport calculations. The comparison unit 11 outputs a warning via the calculation result output unit when the measured value and the calculated value of the count rate of the neutron detector are significantly different.

  In the present embodiment configured as described above, signs of abnormality during the fuel change can be found by using the monitoring for comparing the measured value and the calculated value of the neutron detector count rate data together. The reason for the large difference between the measured value and the calculated value is that the core condition is different from what is planned in the work plan. The fuel arrangement before fuel change and the fuel movement data set in the fuel changer are not consistent. Some neutron detectors are not functioning properly. By discovering and warning these possibilities, it contributes to improving the safety of work at cold temperatures.

  In addition, by automatically recording the monitoring results periodically or for each work step, it is possible to leave an accurate record regarding safety of the core state during the reactor shutdown period and the core state during the work.

<Third Embodiment>
A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, a core state variation determination unit 12 (core state variation determination means) is added to the first embodiment of FIG. In the core state variation determination unit 12, control rod operation procedures, fuel movement procedure information, and the like are registered in advance, and the core state variation determination unit 12 performs control rod operation procedures and fuel movement procedures registered in advance. By comparing the information with the actual control rod position data input via the core data input unit 2 and the fuel movement data, it is monitored that no unexpected event has occurred in the core. Further, the control unit 1 uses the event trigger function (automatic startup function at the time of core abnormality) in the core state variation determination unit 12 even if there is no waiting state for periodic startup of periodic core state evaluation or a startup request from an operator. When it is estimated that an abnormal event has occurred in the core, the criticality monitoring function of the cold-temperature core characteristic monitoring unit 3 is automatically activated, and the cold-temperature core characteristic monitoring unit 3 outputs the evaluation monitoring result as a calculation result. The data is output from the unit 7 to the display device and the printer. Further, as a result of these, they are recorded and stored in the record storage database unit 8.

  In the present embodiment, the event trigger function (automatic activation function when the reactor core is abnormal) causes a situation such as an accidental pulling out of the control rod. Even when there is no request, it is possible to automatically activate the subcriticality evaluation function and perform high-precision criticality evaluation and record storage. In addition, it is possible to contribute to safety improvement activities of nuclear power plants by providing useful information during analysis work for more detailed core characteristics elucidation performed after the stabilization of abnormal events. .

It is a figure which shows the structure of the core monitoring apparatus concerning the 1st Embodiment of this invention. It is a figure which shows the structure of the core monitoring apparatus concerning the 2nd Embodiment of this invention. It is a figure which shows the structure of the core monitoring apparatus concerning the 3rd Embodiment of this invention.

Explanation of symbols

1 Control Unit 2 Core Data Input Unit 3 Cold Temperature Core Characteristic Monitoring Unit (Cool Temperature Core Monitoring Means)
4 Fuel status database section (Fuel status storage means)
5 Fuel Arrangement Database Unit 6 Operating Core Characteristics Monitoring Unit 7 Record Storage Database Unit (Evaluation Result Storage Unit)
8 Calculation result output section 9 Core simulator section (cold temperature core monitoring means)
10 Coefficient rate data processing unit (cold temperature core monitoring means)
11 Comparison section (cold temperature core monitoring means)
12 Core state fluctuation judgment unit (Core state fluctuation judgment means)

Claims (4)

Fuel state storage means for storing the actual combustion state information of each fuel assembly in the reactor core obtained during the operation of the reactor;
Obtaining control rod position information and coolant temperature information in the reactor core during the operation of the reactor, calculating the actual combustion state of each fuel assembly in the reactor core, and the fuel state storage means as the actual combustion state information Operating core monitoring means to record and store in
Obtain control rod position information, coolant temperature information and fuel assembly arrangement information in the reactor core when the reactor is shut down at regular and operator requests, and control rod position information and coolant temperature information. Based on the fuel assembly arrangement information and the actual combustion state information of each fuel assembly stored in the fuel state storage means, the neutron effective multiplication factor of the core state is sequentially calculated by neutron diffusion calculation or transport calculation, etc. Cold core monitoring means for evaluating subcriticality,
A core monitoring apparatus comprising: an evaluation result storing means for recording and storing the evaluation result of the subcriticality by the cold temperature core monitoring means. Fuel state storage means for storing the actual combustion state information of each fuel assembly in the reactor core obtained during the operation of the reactor;
Obtaining control rod position information and coolant temperature information in the reactor core during the operation of the reactor, calculating the actual combustion state of each fuel assembly in the reactor core, and the fuel state storage means as the actual combustion state information Operating core monitoring means to record and store in
Each time fuel movement information is acquired from the fuel changer, the fuel assembly arrangement information stored in advance is updated, and control rod position information and coolant temperature information are acquired periodically or simultaneously with fuel movement information acquisition. Control rod position information, coolant temperature information, fuel assembly arrangement information, and actual combustion state information of each fuel assembly in the core stored in the fuel state storage means, by neutron diffusion calculation or transport calculation, etc. A cold core monitoring means for sequentially calculating the effective neutron multiplication factor of the core state and evaluating the subcriticality after fuel transfer;
A core monitoring apparatus comprising: an evaluation result storing means for recording and storing the evaluation result of the subcriticality by the cold temperature core monitoring means. Fuel state storage means for storing the actual combustion state information of each fuel assembly in the reactor core obtained during the operation of the reactor;
Obtaining control rod position information and coolant temperature information in the reactor core during the operation of the reactor, calculating the actual combustion state of each fuel assembly in the reactor core, and the fuel state storage means as the actual combustion state information Operating core monitoring means to record and store in
Each time fuel movement information is acquired from the fuel changer, the fuel assembly arrangement information stored in advance is updated, and control rod position information and coolant temperature information are acquired periodically or simultaneously with fuel movement information acquisition, and Obtain count rate data from the neutron detector, control rod position information and coolant temperature information, fuel assembly arrangement information, and the actual combustion state of each fuel assembly in the core stored in the fuel state storage means Based on the information, calculate the count rate of the neutron detector by neutron diffusion calculation or transport calculation, etc., and compare this with the measured coefficient rate calculated from the coefficient rate data of the neutron detector, so that abnormalities during fuel transfer work A cold-temperature core monitoring means for monitoring
A core monitoring apparatus comprising: an evaluation result storing means for recording and storing an abnormality monitoring result by the cold temperature core monitoring means. The core state information including the obtained control rod position information and fuel assembly arrangement information is compared with the operation information including control rod operation information and fuel transfer procedure information registered in advance, and whether the states of both are consistent. Further has a core state variation determination means for determining
The cold-temperature core monitoring means automatically activates the subcriticality evaluation function when the core state information and the operation information do not match by the core state variation determination means, and the evaluation result is stored in the evaluation result storage means. The core monitoring apparatus according to any one of claims 1 to 3, wherein the core monitoring apparatus is recorded and stored.

Images