JP7399767B2 - Emergency response support equipment, methods and programs - Google Patents

Description

Embodiments of the present invention relate to technology for supporting emergency response in a nuclear power plant.

When an abnormal situation such as an accident occurs at a nuclear power plant, there is a central control room that monitors and controls the plant equipment, and an emergency response center that is installed on the site of the nuclear plant and that plans accident countermeasures and makes decisions. Countermeasures will be taken while sharing plant information with off-site locations such as the power company's head office that provides logistical support. In this case, one of the important roles of the emergency response center is to notify the relevant organizations as to which category of the predetermined emergency activity level (EAL) the abnormal situation that has occurred falls under. Can be mentioned.

Emergency Action Level (EAL) refers to the standard for determining the urgency of an abnormal situation in a nuclear power plant. The emergencies that are determined are "Alert" (AL), "Site area Emergency" (SE), and "General Emergency" (GE) based on facility information, radiation levels, etc. )” are broadly classified into three types. Furthermore, the EAL indicates criteria for determining which of these three types of emergency situations an abnormal situation that has occurred falls into.

The person in charge of the emergency response center (e.g., nuclear disaster prevention manager/support staff, hereinafter referred to as "human system") should determine whether an emergency situation (AL, SE, or GE) has been reached after an abnormal situation occurs at a nuclear power plant. You will be forced to decide whether or not to do so. In such a case, a plant monitoring support system is known that provides necessary information to comprehensively support the human system in determining whether the EAL has been reached.

JP2017-27328A

When an abnormal situation occurs in a nuclear power plant, it is desirable to start preparing countermeasures as early as possible and to promptly recommend countermeasures. Therefore, in this case, it is desirable that EAL candidates that are likely to be reached are known in advance before the determination of whether the EAL has been reached is actually made. However, in the above-mentioned known plant monitoring support system, the information necessary for the human system to make a determination that EAL has been reached is only provided based on the collected plant data, and it is difficult to meet such requests. was difficult.

On the other hand, probabilistic risk assessment (PRA) has been introduced to nuclear power plants, which enables comprehensive analysis and quantification of accident sequences. PRA aimed at evaluating core damage frequency (CDF) is called Level 1 PRA.

The embodiments of the present invention have been made taking these circumstances into consideration, and approach nuclear power plants from a probabilistic risk assessment method, grasp in advance EAL candidates that are likely to be reached, and prepare countermeasures. The purpose is to provide emergency response support technology that can take early action and quickly recommend countermeasures.

In the emergency response support device according to the embodiment, when an abnormal situation occurs in a nuclear power plant, a first registration unit that registers an EAL classification indicating a criterion for an emergency activity level, which is a criterion for determining an emergency; a second registration unit that registers an event tree that expands success/failure branches in a series of action items for preventing the progression of a situation caused by an event; and a final state of each sequence expanded by the branches of the event tree. a third registration unit that registers the branch probability of success or failure in each of the branches; and a third registration unit that registers the branch probability of success or failure in each of the branches; an acquisition unit that acquires a determined result of failure; and an acquisition unit that selects either the success or the failure in the branch based on the branch probability along the sequence that is developed downstream of the branch in which the determined result is indicated. and a calculation unit that calculates the probability of arrival of the EAL division by setting the probability Q to the branch probability 1−Q .

According to an embodiment of the present invention, it is possible to approach nuclear power plants from a probabilistic risk assessment method, grasp in advance EAL candidates that are likely to be reached, start preparing for countermeasures at an early stage, and promptly recommend countermeasures. The purpose is to provide emergency response support technology that can

FIG. 1 is a block diagram of an emergency response support device according to an embodiment of the present invention. A matrix table showing EAL classifications that serve as criteria for determining emergency activity levels. (A) A diagram showing a PRA event tree for probabilistic risk assessment, (B) a diagram showing an event tree in which EAL classifications are associated with the final state of a sequence. An image generated and displayed by an image generation unit. An image of a facility site emergency (SE) event tree and table displayed immediately after the initiating event begins. An image of an event tree and table of a facility site emergency (SE) that is displayed as the situation progresses due to the initiating event. 1 is a flowchart of an emergency response support method and an emergency response support program according to an embodiment.

Embodiments of the present invention will be described below based on the accompanying drawings. FIG. 1 is a block diagram of an emergency response support device 10 according to an embodiment of the present invention. FIG. 2 is a matrix table showing EAL classifications 35 that serve as criteria for determining emergency activity levels. FIG. 3(A) is a diagram showing a PRA event tree 20x for probabilistic risk assessment. FIG. 3B is a diagram showing an event tree 20 in which the final state 25 of the sequence 26 is associated with the EAL classification 35.

As shown in FIG. 1, the emergency response support device 10 includes a first registration unit 11 that registers the EAL category 35 (FIG. 2) that indicates criteria for determining the emergency activity level, and prevents the development of a situation caused by an initiating event. a second registration unit 12 that registers an event tree 20 that expands the success/failure branch 27 (27x, 27a, 27b...) in a series of action items 24 (24x, 24a, 24b...) (FIG. 3); an association unit 15 that associates the EAL classification 35 with the final state 25 of each sequence 26 expanded by the branch 27 of the tree 20; a third registration unit 13 that registers the branch probability Q of success or failure in each branch 27; An acquisition unit 16 that acquires the determined result R of success/failure of the branch 27 after the start of the initiating event, and a sequence 26β (FIG. 6) developed downstream of the branch 27α (FIG. 6) where the determined result R is shown. ) for calculating the arrival probability P of the EAL classification 35 based on the branch probability Q (FIG. 3(B)).

FIG. 4 shows an image 29 generated and displayed by the image generation section 19 (FIG. 1). In this way, the image generation unit 19 generates and displays images 29 of the event tree 20 (20 ₁ , 20 _{2 .} . . ) in which the EAL classification 35 is associated with the final state 25 for each type of initiating event. Further, the image 29 generated by the image generation unit 19 can be displayed on a display terminal 32 (32a, 32b) located in another area via the communication network 31 (FIG. 1).

In FIG. 4, the EAL classification 35 is divided into a facility site emergency (SE) and a general emergency (GE), and separate event trees 20 (20x ₁ , 20y ₁ , 20x ₂ , 20y ₂ . . . ) are displayed for each. ing. Note that the display format is not limited to this, and a list may be displayed by type of initiating event without distinguishing between facility site emergency (SE) and general emergency (GE).

In addition, the event tree 20 (20 ₁ , 20 ₂ , ...) displayed in the image 29 is an input section (not shown) by a human system that targets one or more possible initiating events when an abnormal situation occurs. It may be selected by operation. Furthermore, it is possible to delete any of the event trees 20 (20 ₁ , 20 ₂ , . . . ) displayed on the image 29, or to newly display an event tree 20 of another initiating event.

The emergency activity level (EAL) is a standard for determining the emergency level when an abnormal situation occurs at a nuclear power plant. The emergency situations determined as shown in Figure 2 are "Alert", "Site area emergency" (SE), and "Full-scale emergency" based on facility information, radiation dose, etc. (GE: General Emergency).

Further, the emergency activity level (EAL) is defined in terms of criteria for determining which EAL category 35 an emergency situation falls under. In the following, when referring to a specific EAL division 35, the item number identifying the row of the matrix in FIG. 2 and the symbol identifying the column are used, for example, SE27, GE42.

The criterion for an alert situation (AL) is when the safety level of the plant has decreased, or when an event that has the possibility of decreasing the safety level has occurred. Preparations for evacuation of people requiring assistance in the event of a disaster will begin.

A facility site emergency (SE) is determined based on the occurrence of a loss of plant functionality required to protect the public, or the occurrence of an event with the possibility of such loss; in this case, the PAZ Evacuation of those who require assistance in the event of a disaster will be carried out, and evacuation preparations will be carried out for residents within the PAZ.

A general emergency (GE) is an event in which core damage or fuel meltdown has occurred or is likely to occur, as well as an event that may result in loss of containment integrity. In this case, the residents in the PAZ will be evacuated and the UPZ (area for preparing emergency protection measures) will be evacuated indoors.

Returning to FIG. 1, the explanation will be continued.
The EAL categories 35 registered in the first registration unit 11 are those classified into at least facility site emergency (SE) and general emergency (GE) among the emergency activity levels shown in FIG.

The event tree 20 registered in the second registration unit 12 is based on probabilistic risk assessment (PRA) and is a series of action items to prevent the development of the situation caused by the initiating event, as shown in FIG. 3(A). 24 (24a, 24b...) are heading. Further, in the event tree 20, a sequence 26 having success/failure branches 27 (27a, 27b, . . .) is developed for each action item 24 (24a, 24b, . . .).

The PRA event tree 20x of the probabilistic risk assessment model shown in Figure 3 (A) was constructed to evaluate the core damage frequency (CDF) at level 1 PRA, with "loss of water supply" as the initiating event. It is something. A plurality of measures to prevent the progression to core damage are headed in chronological order as action items 24 (24a, 24b...). Then, the sequence 26 branches 27 depending on the success/failure of the countermeasure for each action item 24 (24a, 24b, . . . ), and is expanded to the final state 25.

Here, "OK" in the final state 25 indicates that the progression of the accident from the initiating event to core damage has been successfully prevented, and "NG" indicates that the prevention of the progression has failed. Although "loss of water supply" is illustrated as an initiating event, a plurality of other initiating events are defined based on probabilistic risk assessment (PRA).

The association unit 15 (FIG. 1) associates the EAL classification 35 with the final state 25 of each sequence 26 developed by the branch 27 of the PRA event tree 20x (FIG. 3(A)). Thereby, the arrival probability P of each EAL classification 35 can be evaluated based on the event tree 20x constructed for another purpose (for example, CDF evaluation at level 1 PRA). That is, the emergency activity level (EAL) can be evaluated by changing the final state 25 of the event tree 20x from "OK" or "NG" for core damage evaluation to the probability P of SE or GE arrival.

FIG. 3B shows an event tree 20 obtained by adding a newly established action item 24x to the PRA event tree 20x shown in FIG. When associating the EAL classification 35 with the end state 25, the SE and GE corresponding to the treatment item 24, such as loss of relaxation function, are directly associated.

On the other hand, for EALs that are established by a combination of conditions, such as barrier loss, the conditions are organized and associated with the final state 25, such as by adding a newly established action item 24x, as shown in Figure 3 (B). It will be done. That is, if there is a final state 25 that cannot be directly associated with the EAL classification 35, a new action item 24x is added to the event tree 20 so that it can be associated, and the sequence 26 is redeployed.

The third registration unit 13 (FIG. 1) registers the success or failure probability Q of each branch 27 (27x, 27a, 27b, . . . ). In FIG. 3(B), branch probabilities of failure Q (Q _x , Q _a , Q _{b .} . . ) are shown. In this case, the branch probability of success is denoted by 1-Q.

This branching probability Q can be obtained from fault tree analysis for each action item 24 (24x, 24a, 24b, . . . ) or case analysis accumulated so far. Fault tree analysis is to derive the causal events that lead the action item 24 to "fail", connect them with logical symbols such as AND and OR, develop them into a tree, and calculate the action item 24 at the apex from the probability of occurrence of the causal event located at the end. The branch probability Q of failure in is calculated.

The acquisition unit 16 (FIG. 1) acquires the determined success/failure result R of the branch 27 after the start of the initiating event. When an abnormal situation occurs in the plant, a series of action items 24 (24x, 24a, 24b, . . . ) in the event tree 20 also progresses in accordance with its progress. The determined success/failure results R for these action items 24 (24x, 24a, 24b, . . . ) are input from the outside based on human judgment or plant process signals.

The calculation unit 18 (FIG. 1) calculates the arrival probability P of the EAL section 35 based on the branch probability Q along the sequence 26β that is expanded downstream from the branch 27α (see FIG. 6) in which the final result R is shown. do. Here, a method for calculating the arrival probability P will be explained based on FIG. 3(B). A failure branch probability Q (Qx, Qa, Qb, . . .) is associated with each branch 27 (27x, 27a, 27b, . . .) of the sequence 26. In this case, the arrival probabilities P of GE23, GE42, and GE22 are as follows: P _GE23 = Qx・(1−Qa)・Qd, P _GE42 = Qx・Qa・(1−Qb), P _GE22 = Qx・Qa・Qb is expressed in

FIG. 5 is an image of the event tree 20a (20) and table 21a (21) of a facility site emergency (SE) that is displayed immediately after the initiating event of the main steam relief safety valve being stuck open is initiated. In this case, since the trigger event has just started, the final result R is not shown in any of the action items 24. In this case, the calculation unit 18 calculates the arrival probability P of the EAL section 35 based on the branch probability Q along the sequence 26 expanded from the start end. Although not described here, the same explanation as for the facility site emergency (SE) also applies to the event tree 20 and table 21 for the general emergency (GE).

The arrival frequency 36 of the corresponding sequence 26 is attached to the final state 25 of the event tree 20. The arrival frequency 36 is obtained by multiplying the branching probability Q calculated along the sequence 26 from the start to the end by the frequency of occurrence of the initiating event. Note that, unlike the arrival probability P, the arrival frequency 36 always shows a fixed value regardless of the progress of the situation.

In the event tree 20, the position 37 of the treatment item 24 currently in progress is highlighted with a black circle. Furthermore, a direction 38 that is likely to develop in the future is highlighted with an arrow, and a branching probability Q in that direction 38 is displayed. In the example of Figure 5, the branching probability Q = 2.0E-7 for "water level measurement" to proceed to "failure", and the probability (1-Q) for "water level measurement" to proceed to "success" = 1-2.0E- It is 7.

The table 21 is displayed in the image 29 (FIG. 4) along with the corresponding event tree 20, and lists EAL categories 35 ranked based on the probability of arrival P. The arrival probabilities P of the same EAL divisions 35 associated with each final state 25 are added up, and the EAL divisions 35 with the highest probability of arrival P are listed in order.

In the example of Figure 5, the EAL categories 35 (Figure 2) that may be reached are SE22 (risk of loss of reactor water injection function), SE23 (loss of residual heat removal function), and SE42 (loss of two barriers). or loss possibility), and the probability P of reaching a facility site emergency (SE) is large in the order of SE22, SE23, and SE42.

FIG. 6 is an image of the event tree 20b (20) and table 21b (21) of a facility site emergency (SE) that is displayed as the situation progresses with the main steam relief safety valve stuck open as the triggering event. In Figure 6, in the process where the situation is progressing due to the initiating event, a definite result R is obtained that "water level measurement" is "successful" and "water supply and condensate system water injection" is "failed" among the series of action items 24. represents the state. As a result, the currently ongoing treatment item 24 highlighted with a black circle becomes the position 37 of "high pressure water injection".

Then, a sequence 26α that is expanded upstream from the next branch 27β, which is downstream of the final branch 27α where the confirmed result R is shown, is highlighted (indicated by a solid line in the figure). Note that the sequence 26β on the downstream side from the next branch 27β may be displayed in an emphasized manner. Further, the success/failure branch probability P corresponding to the next branch 27β is also displayed (0.95, 0.05, etc.).

Furthermore, the EAL section 35 is displayed in an emphasized manner in the branch 27 and its final state 25 along the sequence 26β that is developed downstream from the next branch 27β. It is suggested that the EAL section 35 emphasized in this way is likely to be reached in the future.

In the example of FIG. 6, the probability that "high pressure water injection" progresses to "failure" = 0.05, and the probability that "high pressure water injection" progresses to "success" = 0.95. The EAL categories 35 (FIG. 2) that may be reached are SE22 (risk of loss of reactor water injection function) and SE23 (loss of residual heat removal function). After the initiating event (main steam relief safety valve stuck open) starts, "water level measurement" is "successful", and "water supply and condensate system water injection" fails, the probability P of reaching a facility site emergency (SE) is SE23. , SE22.

In the example of FIG. 6, compared to the example of FIG. 5 which shows the situation immediately after the triggering event starts, the number of possible EAL categories 35 that can be reached is narrowed down from three to two. Based on such knowledge, it is possible to predict risks, narrow down the candidates for EALs that are likely to be reached, increase the speed of decision-making, and begin preparing countermeasures as soon as possible.

An emergency response support method and an emergency response support program according to the embodiment will be explained based on the flowchart of FIG. 7 . First, the EAL section 35 and the event tree 20 are registered (S11, S12), and the EAL section 35 is associated with the final state 25 of the sequence 26 of the event tree 20 (S13). Furthermore, the branch probability Q of success or failure in each branch 27 is registered (S14).

After the abnormal situation occurs (S15 Yes), the event tree 20 (20 ₁ , 20 ₂ , . . . ) of one or more initiating events that can be reached is selected and displayed on the image 29 (S16). Next, the arrival probability P of the EAL section 35 is calculated based on the branching probability Q along the sequence 26 developed from the start end to the end end (S17). Furthermore, the table 21 in which the EAL categories 35 ranked based on the calculated arrival probability P is displayed together with the corresponding event tree 20 (S18).

As the series of action items 24 progress, the success/failure determination result R of the branch 27 is obtained (S19 Yes). Then, the arrival probability P of the EAL section 35 is recalculated based on the branch probability Q along the sequence 26 developed downstream of the branch 27α where the final result R is indicated (S17). Furthermore, the table 21 in which the EAL categories 35 ranked based on the recalculated arrival probability P is redisplayed together with the corresponding event tree 20 (S18).

Then, the determined result R of the branch 27 that expands the event tree 20 is obtained, and the sequence 26 ends when it reaches the final state 25 (S19 No, S20 Yes, END).

According to the emergency response support device of at least one embodiment described above, nuclear power plants are approached from a probabilistic risk assessment method, EAL candidates that are likely to be reached are grasped in advance, and countermeasures are prepared. It is possible to take action early and quickly recommend countermeasures.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, changes, and combinations can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

The emergency response support device described above includes a control device with a highly integrated processor such as a dedicated chip, FPGA (Field Programmable Gate Array), GPU (Graphics Processing Unit), or CPU (Central Processing Unit), and a ROM. (Read Only Memory) and RAM (Random Access Memory), external storage devices such as HDD (Hard Disk Drive) and SSD (Solid State Drive), display devices such as displays, and mouse and keyboard devices. It is equipped with an input device and a communication I/F, and can be realized with a hardware configuration using a normal computer.

Further, the program executed by the emergency response support device is provided by being pre-installed in a ROM or the like. Alternatively, this program is provided as an installable or executable file stored on a computer-readable storage medium such as a CD-ROM, CD-R, memory card, DVD, or floppy disk (FD). You may also do so.

Further, the program executed by the emergency response support device according to the present embodiment may be stored on a computer connected to a network such as the Internet, and may be provided by being downloaded via the network. Further, the emergency response support device can also be configured by combining separate modules that independently perform the respective functions of the components by interconnecting them via a network or a dedicated line.

10... Emergency response support device, 11... First registration unit, 12... Second registration unit, 13... Third registration unit, 15... Association unit, 16... Acquisition unit, 18... Calculation unit, 19... Image generation unit, 20 (20a, 20b)...Event tree, 21 (21a, 21b)...Table, 24...Treatment item, 25...Final state, 26...Sequence, 27...Branch, 27α...Determined branch, 27β...Next branch, 29...Image , 31... Communication network, 32... Display terminal, 35... EAL classification, 36... Arrival frequency, P... Arrival probability, Q... Branch probability, R... Determined result.

Claims (10)

a first registration unit that registers EAL classifications that indicate criteria for determining emergency activity levels that are used as criteria for determining urgency when an abnormal situation occurs at a nuclear power plant ;
a second registration unit that registers an event tree that expands success/failure branches in a series of measures to prevent the development of a situation caused by the initiating event;
an association unit that associates the EAL classification with a final state of each sequence expanded by the branch of the event tree;
a third registration unit that registers the branch probability of success or failure in each of the branches;
an acquisition unit that acquires the determined success/failure result of the branch after an abnormal situation occurs and the triggering event starts;
Based on the branch probability along the sequence that is developed downstream of the branch where the confirmed result is shown, if either the success or the failure is the branch probability Q, the other is the branch probability. An emergency response support device comprising: a calculation unit that calculates the probability of arrival of the EAL classification as probability 1-Q . The emergency response support device according to claim 1,
An emergency response support device comprising an image generation unit that generates and displays an image of the event tree in which the EAL classification is associated with the final state for each type of initiating event. The emergency response support device according to claim 2,
An emergency response support device that distinguishes the EAL classification into a facility site emergency (SE) and a general emergency (GE) and displays separate event trees for each. In the emergency response support device according to claim 2 or 3,
An emergency response support device that displays a table listing the EAL categories ranked based on the arrival probability together with the corresponding event tree. In the emergency response support device according to any one of claims 2 to 4,
An emergency response support device that emphasizes and displays the sequence that is expanded to at least one of the upstream side and the downstream side from the branch immediately downstream of the branch where the confirmed result is shown. In the emergency response support device according to any one of claims 2 to 5,
emergency response for emphasizing and displaying the EAL classification on at least one of the branch and its final state along the sequence that is developed downstream from the branch immediately downstream of the branch where the confirmed result is shown; Support equipment. In the emergency response support device according to any one of claims 2 to 6,
An emergency response support device that displays the frequency of arrival of the EAL category associated with the final state of the sequence. In the emergency response support device according to any one of claims 2 to 7,
An emergency response support device that displays the branch probability of success/failure corresponding to the branch immediately downstream of the branch for which the confirmed result is shown. a step of registering, in the first registration section, an EAL classification indicating a criterion for an emergency activity level , which is a criterion for determining the emergency level when an abnormal situation occurs in a nuclear power plant ;
registering, in a second registration section, an event tree that expands success/failure branches in a series of measures to prevent the development of a situation caused by the initiating event;
associating the EAL classification with the final state of each sequence expanded by the branch of the event tree;
registering the branch probability of success or failure in each of the branches in a third registration unit;
obtaining a determined result of the success/failure of the branch after an abnormal situation has occurred and the initiating event has started;
When the calculation unit sets either the success or the failure as the branch probability Q based on the branch probability along the sequence that is expanded downstream from the branch in which the confirmed result is shown. An emergency response support method comprising the step of calculating the arrival probability of the EAL classification , with the other being the branch probability 1-Q . to the computer,
a step of registering an EAL classification indicating a criterion for emergency activity level , which is a criterion for determining emergency when an abnormal situation occurs in a nuclear power plant ;
a step of registering an event tree that expands success/failure branches in a series of action items to prevent the development of a situation caused by the initiating event;
associating the EAL partition with a final state of each sequence developed by the branch of the event tree;
registering the branch probability of success or failure in each of the branches;
obtaining a determined result of the success/failure of the branch after an abnormal situation occurs and the initiating event starts;
Based on the branch probability along the sequence that is developed downstream of the branch where the confirmed result is shown, if either the success or the failure is the branch probability Q, the other is the branch probability. An emergency response support program that executes the step of calculating the probability of arrival of the EAL category as probability 1-Q .

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