Nuclear emergency decision support device, method and program

Abstract

To provide a technique for supporting decision-making to make a plan for secure public evacuation in nuclear emergency on the basis of information having uncertainty.SOLUTION: A device 10 for supporting decision-making in nuclear emergency comprises a first registration unit 11 which registers an event tree 20, a determination unit 22 which determines execution results (success / failure) of procedures 17 (17a, 17b, etc.), an extraction unit 25 which extracts sequences S on the basis of determinations of the determination unit 22, a second registration unit 12 which registers branching probabilities Q in the individual procedures 17, a calculation unit 26 which calculates attainment probabilities P (P1, P2, etc.) of the sequences S (S1, S2, etc.) on the basis of the branching probabilities Q, a third registration unit 13 which registers start times T to environmental release of radioactive materials in the individual sequences S, and a generation unit 27 which generates a graph on the basis of the start times T (T1, T2, etc.) and the attainment probabilities P (P1, P2, etc.) in the extracted individual sequences S (S1, S2, etc.).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a technology for supporting decision-making in a nuclear emergency. [Background technology]

[0002] In order to reduce the risk of public exposure to radiation in the event of an abnormality occurring at a nuclear facility, the Nuclear Emergency Response Guidelines enacted by the Nuclear Regulation Authority stipulate that preventive evacuation of the public be carried out before radioactive materials are released into the environment. An operation is being considered in which an alert is issued based on the emergency action level (EAL) corresponding to the state of the nuclear facility, and preparations and implementation of public evacuation are made.

[0003] Emergency action levels (EALs) are standards for determining the level of urgency when an abnormality occurs at a nuclear facility. EALs are broadly classified into three types: "alert state," "facility site emergency," and "full-scale emergency," based on facility information, radiation levels, etc.

[0004] In the event of a nuclear disaster, the national government or the operator will issue an EAL warning and instruct local governments on evacuation and other measures based on the Nuclear Emergency Response Guidelines, depending on the circumstances of the nuclear power plant accident. In response, local governments will draw up specific evacuation routes and evacuation destinations based on their local disaster prevention plans and taking into account the actual conditions of the area, and will instruct residents to evacuate.

[0005] On the other hand, a nuclear emergency response system is known that identifies an initiating event based on operation information of a nuclear facility, analyzes the progression of the event from the identified initiating event, and develops an evacuation plan based on radiation exposure prediction derived from the analysis results. This known technology makes it possible to predict the start time of the release of radioactive materials.

[0006] Furthermore, there are known methods for evaluating the timing of EAL based on event progression analysis, and for evaluating the risk of exposure when protective measures are implemented, taking into account the time to core damage and the time to containment vessel failure. These known techniques make it possible to predict the timing of EAL and the time to containment vessel failure. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2003-215246 A [Non-patent literature]

[0008] [Non-Patent Document 1] S / NRA / R Research Report "Research on the Use of Risk Information Related to Emergency Action Levels (EALs)" RREP-2020-2003, 2020 Summary of the Invention [Problem to be solved by the invention]

[0009] In the above-mentioned regional disaster prevention plan, the completion time of public evacuation is used as a judgment index for optimizing protection. For this reason, the regional disaster prevention plan has a preparation and implementation procedure planned so that the public evacuation can be completed in the shortest time after the EAL warning is issued. Therefore, the regional disaster prevention plan so far has been unable to grasp information such as how much time there is between the EAL warning being issued and the start of the release of radioactive materials, or the urgency of evacuation. For this reason, when an abnormality occurs at a nuclear facility, it has been difficult for local governments that prepare and implement public evacuations to formulate a safe evacuation plan.

[0010] In addition, the above-mentioned publicly known technology can predict the start time of the release of radioactive materials in a hypothetical accident scenario. However, in reality, the predicted value of the start time of the release of radioactive materials has a large degree of uncertainty due to the unknown nature of the phenomenon and the ever-changing situation. It has been difficult to support the decision-making of local governments based on information with such uncertainty.

[0011] An embodiment of the present invention has been made in consideration of the above circumstances, and has an object to provide a decision-making support technology for a nuclear emergency, for planning a safe public evacuation based on information that has uncertainty. [Means for solving the problem]

[0012] In the nuclear emergency decision support device according to the embodiment, a first registration unit registers an event tree made up of a plurality of sequences in which branches are defined by the execution results of success / failure in a series of measures to prevent the progression of a cause of a nuclear disaster, a determination unit identifies the cause of the initiating event that has occurred based on operation information and further determines the execution results of the corresponding measures in the event tree, an extraction unit extracts the sequences that have the possibility of reaching an end state and have a probability of releasing radioactive materials into the environment based on the determination of the determination unit, a second registration unit registers a branch probability of whether the execution result in each of the measures is successful or unsuccessful, a calculation unit calculates the frequency of reaching the end state in each of the extracted sequences based on the branch probability of the branch located in the measure whose execution result is undetermined, a third registration unit registers a start time from the occurrence of the cause of the initiating event to the release of the radioactive materials into the environment in each of the sequences, and a calculation unit calculates a start time for each of the extracted sequences based on the start time and the arrival frequency in each of the extracted sequences. , which indicates the start time and the probability of the radioactive material being released into the environment A creating unit that creates a graph. Effect of the Invention

[0013] An embodiment of the present invention provides a nuclear emergency decision support technique for planning safe public evacuation based on information with uncertainty. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram of a decision support device for a nuclear emergency according to a first embodiment of the present invention. [Diagram 2] An event tree consisting of multiple sequences. [Diagram 3] A formula for calculating the frequency of reaching the final state of a sequence based on branching probabilities. [Figure 4] (A) An event tree showing the sequence extraction status when the execution result of the first action item is “success”. (B) An event tree showing the sequence extraction status when the execution result of the next action item is “failure”. [Diagram 5] A graph showing the start time and probability of a release of radioactive materials into the environment at the current time after the occurrence of an initiating event. [Figure 6] FIG. 11 is a block diagram of a decision support device for a nuclear emergency according to a second embodiment. [Figure 7] (A) A table showing an assessment index of the severity of public evacuation in each of the sequences in the second embodiment, and (B) a display result showing the urgency of public evacuation. [Figure 8] In the second embodiment, (A) a graph showing the start time and the probability of radioactive material being released into the environment when the execution result of the first action item after the occurrence of a triggering event is "success", and (B) a graph showing the start time and the probability of radioactive material being released into the environment when the execution result of the next action item after the execution of the first action item is "failure". [Figure 9] FIG. 11 is a block diagram of a decision support device for a nuclear emergency according to a third embodiment. [Figure 10] FIG. 13 is a block diagram of a decision support device for a nuclear emergency according to a fourth embodiment. [Figure 11] 2 is a flowchart showing the steps of a decision-making support method in a nuclear emergency according to an embodiment and an algorithm of the decision-making support program. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (First embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of a nuclear emergency decision support device 10A (10) (hereinafter simply referred to as "device 10A") according to a first embodiment of the present invention. FIG. 2 shows an event tree 20 composed of a plurality of sequences S (S1, S2, ...). FIG. 3 shows a branch probability Q (Q a ,Q b This is a formula for calculating the frequency P (P1, P2 ...) of arrival at the final state of a sequence S (S1, S2, ...) based on the

[0016] In this way, the device 10A includes a first registration unit 11 that registers an event tree 20 composed of a plurality of sequences S (S1, S2, ...) in which branches 14 (14a, 14b, ...) are defined by the success / failure of the execution results of a series of action items 17 (17a, 17b, ...) that prevent the progression of a triggering event 16 (Figure 2) of a nuclear disaster, and a judgment unit 22 that identifies the triggering event 16 that has occurred based on operation information 15, and further judges the execution results (success / failure) of the action items 17 (17a, 17b, ...) in the corresponding event tree 20.

[0017] Furthermore, the device 10A includes an extraction unit 25 that extracts sequences S that have the possibility of reaching a final state and the probability of releasing radioactive materials into the environment based on the above judgment, and a branch probability (shown in the figure is the branch probability Q (Q a ,Q b The method further comprises: a second registration unit 12 that registers the extracted sequences S (S1, S2, ...), and a calculation unit 26 that calculates the frequency P (P1, P2, ...) of reaching a final state in each of the extracted sequences S (S1, S2, ...) (FIG. 3) based on the branch probability Q of a branch 14 located in a disposition item 17 whose execution result is undetermined.

[0018] The device 10A further includes a third registration unit 13 that registers the start time T from the occurrence of the initiating event 16 in each sequence S to the release of radioactive materials into the environment, and a creation unit 27 that creates a graph based on the start time T (T1, T2, ...) and arrival frequency P (P1, P2, ...) in each of the extracted sequences S (S1, S2, ...).

[0019] The initiating event 16 on the left side of the sequence S (S1, S2, ...) shown in Figure 2 is an event that can be a factor in the progression of an accident leading to a serious accident (such as core damage) that releases radioactive materials into the environment, and several such events have been identified in a probabilistic risk assessment (PRA), for example. Starting from this initiating event 16, several measures to prevent the release of radioactive materials into the environment are chronologically headed as action items 17 (17a, 17b, ...). Each of the sequences S (S1, S2, ...) has branches 14 (14 a ,14 b ...) to the final state at the right end.

[0020] Here, the final state of each sequence S (S1, S2, ...) is associated with whether the release of radioactive materials into the environment was prevented ("OK") or not ("NG"), and in the case where the release of radioactive materials into the environment was not prevented ("NG"), it is further associated with the scale of the release into the environment. A plurality of event trees 20 defined by each of the plurality of types of initiating events 16 are registered in the first registration unit 11.

[0021] Each of the action items 17 (17a, 17b, ...) contributes to preventing the progression of the initiating event 16 if the execution result is "successful", and promotes the progression of the initiating event 16 if the execution result is "failed". Therefore, each of the action items 17 (17a, 17b, ...) has a branch probability Q (Q a ,Q b ...), the initial values ​​of which are registered in the second registration unit 12. These branch probabilities Q (Q a,Q b ...), although detailed explanation will be omitted, can be obtained in advance by a fault tree analysis of a plurality of component devices that executes the action item 17.

[0022] As shown in Figure 3, when the execution results (success / failure) of all the actions 17 (17a, 17b...) are undetermined immediately after the initiating event 16 occurs, the frequency P (P1, P2...) of reaching the final state of each sequence S (S1, S2,...) is expressed by the following formula. Note that the formula shown in Figure 3 shows a typical part, and in reality, other coefficients and variables may be added or the formula may be modified.

[0023] After the occurrence of the initiating event 16, as the execution results (success / failure) of a series of corrective actions 17 (17a, 17b, ...) are determined one by one, the frequency P (P1, P2, ...) of each sequence S (S1, S2, ...) reaching the final state also changes.

[0024] Specifically, if the execution result of the first action item 17a is "success", the branch probability of failure Q a = 0, and P1 = (1-Q b )·(1-Q c ), P2=(1-Q b )·Q c , P3=Q b ·(1-Q c ), P4=Q b Q c , P5=P6=P7=P8=0. If the execution result of the first action item 17a is "failure", the branch probability of failure Q a = 1, P1 = P2 = P3 = P4 = 0, P5 = (1-Q b )·(1-Q c ), P6=(1-Q b )·Q c , P7=Q b ·(1-Q c ), P8=Q b Q c changes to.

[0025] The operation information 15 is a control value that changes from moment to moment, such as a process signal of the nuclear facility, and is acquired in real time by the acquisition unit 21. In the unlikely event that a disaster occurs in this nuclear facility, specific operation information 15 corresponding to the initiating event 16 is acquired. Furthermore, when a corrective action 17 (17a, 17b...) is executed to prevent the initiating event 16 from progressing, specific operation information 15 corresponding to the result of the action, whether it is successful or not, is acquired.

[0026] The judgment unit 22 identifies an initiating event 16 that has occurred in the nuclear facility by analyzing the operation information 15 acquired in real time, and calls up a corresponding event tree 20 from the first registration unit 11. The judgment unit 22 then analyzes the operation information 15 acquired in real time to judge the execution result (success / failure) of a series of action items 17 (17a, 17b...) in the event tree 20. Then, as soon as this judgment is finalized, the execution result (success / failure) is output.

[0027] FIG. 4(A) shows the sequence S(S1, ...S M 4B is an event tree 20 showing the extraction status of the sequence S (S m+1 ,…S M ) is extracted. In this manner, the event tree 20 highlights the route of the sequence S from the position of the initiating event 16 to the position of the branch 14 corresponding to the action item 17 currently being judged by the judgment unit 22.

[0028] The extraction unit 25 (FIG. 1) extracts a sequence S that has the possibility of reaching a final state based on the output of the decision unit 22. That is, as shown in FIG. 4(A), if the execution result of the action item 17a is “success” (branch probability Q a=0; Fig. 3), the arrival frequency P of the sequence S with the "failure" branch 14a becomes 0, making it impossible to reach the final state, while the arrival frequency P of the sequence S with the "success" branch 14a becomes a finite value and makes it possible to reach the final state. On the other hand, as shown in Fig. 4(B), if the execution result of the action item 17b becomes "failure" (branch probability Q a = 1; Figure 3) is determined, the arrival frequency P of the sequence S having the "success" branch 14b becomes 0, making it impossible to reach the final state, whereas the arrival frequency P of the sequence S having the "failure" branch 14b becomes a finite value, making it possible to reach the final state.

[0029] Furthermore, the extraction unit 25 extracts sequences S that have a probability of releasing radioactive materials into the environment, based on the fact that the final state of each sequence S (S1, S2, ...) is associated with "OK" (whether the release of radioactive materials into the environment was prevented) or "NG" (whether the release of radioactive materials into the environment could not be prevented), as described above.

[0030] The calculation unit 26 (Fig. 1) calculates the arrival frequency P(P1, P2, ...) (Fig. 3) from the current time to the final state shown at the end of the highlighting in Fig. 4(A)(B) for each of the extracted sequences S(S1, S2, ...). That is, the calculation unit 26 calculates the arrival frequency P(P1, P2, ...) (Fig. 3) of the extracted sequences S(S1, S2, ...) based on the branch probability Q of the branch 14 located in the action item 17 whose execution result (success / failure) is undetermined.

[0031] The third registration unit 13 registers the start time T from the occurrence of the initiating event 16 in each sequence S (S1, S2, ...) to the release of radioactive materials into the environment. This start time T is obtained in advance using, for example, the MAAP code developed by the Electric Power Research Institute (EPRI). This MAAP code can analyze a series of accident progression processes from core damage in a light water reactor, reactor pressure vessel (RPV) failure, and containment vessel (PCV) failure to core-concrete reactions and the generation, migration, and release of radioactive materials.

[0032] That is, in each sequence S (S1, S2, ...), after the occurrence of an initiating event 16, a process analysis can be performed to determine whether the core can be brought to a state where it can be cooled and the accident will be resolved, or whether the PCV will lose its function and a serious accident will occur, such as releasing radioactive materials into the environment.

[0033] In the event tree 20 (FIG. 2) registered in the first registration unit 11, the final state of a sequence S in which the release of radioactive materials into the environment was prevented through such analysis is associated with "OK" as described above. And the final state of a sequence S in which the release of radioactive materials into the environment was not prevented is associated with "NG" as described above. Furthermore, the "NG" final state is also associated with information on the scale of the release into the environment obtained from this analysis. Furthermore, the start time T registered in the third registration unit 13 is associated with a sequence S having an "NG" final state.

[0034] 5 is a graph showing the start time T of the environmental release of radioactive materials at the current time after the occurrence of the initiating event 16 and its probability. In this graph, the start time T from the "occurrence time" of the initiating event 16 is set in classes divided at regular intervals into start times on the horizontal axis, and the arrival frequency P (P1, P2...) of the corresponding sequence S (S1, S2...) is accumulated to obtain the probability on the vertical axis. This graph is displayed on the display unit 28.

[0035] The creation unit 27 (FIG. 1) creates a graph (FIG. 5) based on the start times T (T1, T2, ...) and arrival frequencies P (P1, P2, ...) of each sequence S (S1, S2, ...) extracted by the extraction unit 25 at the "current time". This makes it possible to plan a safe public evacuation based on information with uncertainty regarding the release of radioactive materials into the environment. As the execution results (success / failure) of a series of action items 17 (17a, 17b, ...) are determined, the uncertainty regarding the release of radioactive materials into the environment decreases, making it possible to plan a safer public evacuation.

[0036] Second embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 6 to Fig. 7. Fig. 6 is a block diagram of a decision support device 10B (10) for nuclear emergency (hereinafter, simply referred to as "device 10B") according to the second embodiment. In Fig. 6, parts having the same configuration or function as Fig. 1 are indicated by the same reference numerals, and duplicated explanations will be omitted.

[0037] As shown in FIG. 6, the device 10B of the second embodiment (see FIG. 2 as appropriate) includes, like the device 10A of the first embodiment, a first registration unit 11 of an event tree 20, a determination unit 22 of action items 17 (17a, 17b, ...), an extraction unit 25 of a sequence S (S1, S2, ...), and a branch probability Q (Q a ,Q b , a calculation unit 26 for the arrival frequency P (P1, P2, . . . ), a third registration unit 13 for the start time T of environmental release, and a creation unit 27 for a graph (FIG. 8).

[0038] Furthermore, the device 10B of the second embodiment is equipped with a first evaluation unit 31 that evaluates the severity of public evacuation for each of the extracted sequences S (S1, S2, ...) based on the scale of the environmental release, and a second evaluation unit 32 that evaluates the urgency of public evacuation based on the point at which the time integrated value of the arrival frequency P (P1, P2, ...) in the graph reaches a threshold value 35.

[0039] Fig. 7(A) is a table showing evaluation indices of the severity of public evacuation in each of sequences S (S1, S2, ...) in the second embodiment. Fig. 7(B) is a display result showing the urgency of public evacuation. In this way, the first evaluation unit 31 ranks the severity of each of sequences S (S1, S2, ...) as shown in Fig. 7(A) based on information such as the arrival frequency P, start time T, and scale of environmental release. Furthermore, the result is displayed on the display unit 28 as shown in Fig. 7(B).

[0040] Fig. 8(A) is a graph showing the start time T of a release of radioactive material into the environment and its probability when the execution result of the first action item 17a after the occurrence of the causal event 16 is "success" as shown in Fig. 4(A). Fig. 8(B) is a graph showing the start time T of a release of radioactive material into the environment and its probability when the execution result of the next action item 17b after the execution of the first action item 17a is "failure" as shown in Fig. 4(B).

[0041] In this way, in the graph of the second embodiment, the horizontal axis represents the class of start time, and the arrival frequency P (P1, P2, ...) stacked along the vertical axis as probability is identified for each severity rank of the sequence S (S1, S2, ...). Furthermore, as shown in Figures 8(A) and 8(B), it is possible to visually confirm how the probability of the severity rank of environmental release is updated in accordance with the execution results of a series of action items 17 (the passage of the "current time").

[0042] The second evaluation unit 32 (FIG. 6) sets the time when the arrival frequency P (P1, P2...) accumulated over time reaches a threshold value 35 as the "scheduled issuance time" of a state of emergency declaration or the like that promotes public evacuation. This "scheduled issuance time" also changes with the execution results of a series of action items 17 (the passage of the "current time"), as shown in FIG. 8(A) to FIG. 8(B).

[0043] This will allow safer public evacuations to be planned based on uncertain information regarding the environmental release of radioactive materials. By allowing local governments to present safer evacuation routes and evacuation timings that take time into consideration, it will be possible to avoid shortages of evacuation support personnel and road congestion, thereby improving the rescue rate. In addition, the simple and clear display method will allow people to understand the situation regardless of their knowledge of nuclear disasters, making it less likely to cause confusion in the transmission of information, etc.

[0044] Third embodiment Next, a third embodiment of the present invention will be described with reference to Fig. 9. Fig. 9 is a block diagram of a nuclear emergency decision support device 10C (10) (hereinafter simply referred to as "device 10C") according to the third embodiment. In Fig. 9, parts having the same configuration or function as Fig. 1 or Fig. 6 are indicated by the same reference numerals, and duplicated explanations will be omitted.

[0045] As shown in FIG. 9, the device 10C of the third embodiment (see FIG. 2 as appropriate) includes, like the device 10B of the second embodiment, a first registration unit 11 of an event tree 20, a determination unit 22 of action items 17 (17a, 17b, ...), an extraction unit 25 of a sequence S (S1, S2, ...), and a branch probability Q (Q a ,Q b The system further comprises a second registration unit 12 for registering the arrival frequency P (P1, P2, ...), a calculation unit 26 for the arrival frequency P (P1, P2, ...), a third registration unit 13 for the start time T of environmental release, a graph creation unit 27 for creating a graph (Figure 8), a first evaluation unit 31 for evaluating the severity of public evacuation, and a second evaluation unit 32 for evaluating the urgency of public evacuation.

[0046] Furthermore, in the device 10C of the third embodiment, the first evaluation unit 31 and the second evaluation unit 32 evaluate the seriousness or urgency of public evacuation based on the environmental information 30 including at least one of meteorological information and environmental radiation information.

[0047] Environmental information 30 consists of climate data from the Automated Meteorological Data Acquisition System (AMeDAS), such as precipitation, snowfall, wind direction, temperature, etc., released by the Japan Meteorological Agency, as well as radiation distribution data and distribution forecast data from the SPEEDI (Speedy Emergency Prediction of Radiation Impact Network System) and emergency monitoring posts, etc.

[0048] The transport analysis unit 36 ​​analyzes the transport direction and distance of radioactive materials based on the environmental information 30 from the location and scale of the radioactive materials released into the environment. This allows for detailed evaluation of the importance and urgency of public evacuation, specific to each region, according to the direction and distance of the surrounding area. This enables local governments to present safe evacuation routes and evacuation timing for each region. This makes it possible to avoid a shortage of evacuation support personnel and road congestion, and improve the rescue rate.

[0049] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to Fig. 10. Fig. 10 is a block diagram of a decision support device 10D (10) for nuclear emergency (hereinafter, simply referred to as "device 10D") according to the fourth embodiment. In Fig. 10, parts having the same configuration or function as Fig. 1, Fig. 6, and Fig. 9 are indicated by the same reference numerals, and duplicated explanations will be omitted.

[0050] As shown in FIG. 10, the device 10D of the fourth embodiment (see FIG. 2 as appropriate) includes, like the device 10A of the first embodiment, a first registration unit 11 of an event tree 20, a determination unit 22 of action items 17 (17a, 17b, ...), an extraction unit 25 of a sequence S (S1, S2, ...), and a branch probability Q (Q a ,Q b , a calculation unit 26 for the arrival frequency P (P1, P2, . . . ), a third registration unit 13 for the start time T of environmental release, and a creation unit 27 for a graph (FIG. 8).

[0051] Furthermore, the device 10D of the fourth embodiment is equipped with an update unit 40 that updates at least one of the branch probability Q and the start time T registered in each of the second registration unit 12 and the third registration unit 13 in accordance with the situation of the nuclear disaster based on the acquired operating information 15.

[0052] As the nuclear disaster initiating event 16 progresses and the state of the nuclear facility changes, the branch probability Q(Q a ,Q b...) may also change from the initial registered value in the second register 12. Alternatively, regardless of the progression of the initiating event 16, a specific device may become unusable due to poor maintenance or an unexpected breakdown, causing the branch probability Q to change from the initial registered value. For the same reason, the start time T (T1, T2, ...) until the radioactive material is released into the environment may also change from the initial registered value in the third register 13.

[0053] Therefore, the update unit 40 updates the branch probability Q and the start time T registered in the second registration unit 12 and the third registration unit 13, respectively, based on the operation information 15 that reflects the state change of the nuclear facility. a ,Q b The start times T (T1, T2, ...) and the start times T (T1, T2, ...) can be updated at any time (for example, every hour). This allows the graphs (Fig. 5 and Fig. 8) to be updated at any time according to the ever-changing state of the nuclear facility.

[0054] This makes it possible to present information that more effectively supports decision-making when a local government plans a safe public evacuation. In addition, when the branch probability Q or the start time T is not updated in the update unit 40, decision-making support information is presented that the state of the nuclear facility will not change for a certain period of time.

[0055] Based on the flowchart in FIG. 11, the steps of the method for supporting decision-making in a nuclear emergency according to the embodiment and the algorithm of the decision-making support program will be described. First, the event tree 20 and the success / failure branch probability Q (Q a ,Q b ...), the start time T of the environmental release of radioactive materials is initially registered (S11, S12, S13). Among these, the branch probability Q (Q a ,Q b ...) and the start time T may be updated from the initial registration based on the operation information 15 obtained from the nuclear facility.

[0056] While acquiring operation information 15 of the nuclear facility, if an initiating event 16 occurs, it is identified (S14 No Yes), and the corresponding event tree 20 is called up from the registration (S15). Furthermore, acquisition of operation information 15 is continued, and the execution result (success / failure) of action items 17 in this event tree 20 is judged (S16 No Yes). Then, based on this execution result (success / failure) judged, a sequence S that has the possibility of reaching an end state and has the probability of releasing radioactive materials into the environment is extracted (S17).

[0057] Among the extracted sequences S (S1, S2, ...), the branch probability Q (Q a ,Q b ...) is called from the register (S18). Then, this branch probability Q (Q a ,Q b Based on the state information, the frequency P(P1, P2, ...) of arrival at the final state of the sequence S(S1, S2, ...) is calculated (S19).

[0058] Next, the start time T of the environmental release associated with the extracted sequence S is retrieved from the registration (S20). Then, a graph (FIGS. 5 and 8) is created and displayed based on the start time T (T1, T2, ...) and arrival frequency P (P1, P2, ...) of each of the extracted sequences S (S1, S2, ...). Then, the processes from (S16) to (S21) are repeated until the execution results of the series of action items 17 in the sequence S are all determined (S22 No Yes END).

[0059] According to at least one of the embodiments of the nuclear emergency decision support device described above, a graph can be created based on the start times and arrival frequencies of the sequences that make up the event tree, making it possible to plan a safe public evacuation based on information that has uncertainty.

[0060] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention.

[0061] The decision support device described above includes a control device with a highly integrated processor such as a dedicated chip, a field programmable gate array (FPGA), a graphics processing unit (GPU), or a central processing unit (CPU), a storage device such as a read only memory (ROM) or a random access memory (RAM), an external storage device such as a hard disk drive (HDD) or a solid state drive (SSD), a display device such as a display, an input device such as a mouse or a keyboard, and a communication I / F, and can be realized with a hardware configuration using a normal computer. Therefore, the components of the decision support device can also be realized by a computer processor and can be operated by a decision support program.

[0062] The decision support program may be provided by being pre-installed in a ROM, etc. Alternatively, the program may be provided by being stored in a computer-readable storage medium such as a CD-ROM, CD-R, memory card, DVD, or flexible disk (FD) in the form of an installable or executable file.

[0063] The decision support program according to the present embodiment may be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. The decision support device may also be configured by combining separate modules that independently perform the functions of the components and are mutually connected via a network or dedicated lines. [Explanation of symbols]

[0064] 10 (10A, 10B, 10C, 10D)... decision support device, 11... first registration unit, 12... second registration unit, 13... third registration unit, 14 (14a, 14b...)... branch, 15... operation information, 16... triggering event, 17 (17a, 17b...)... treatment item, 20... event tree, 21...acquisition unit, 22...determination unit, 25...extraction unit, 26...calculation unit, 27...creation unit, 28...display unit, 30...environmental information, 31...first evaluation unit, 32...second evaluation unit, 35...threshold value, 36...transportation analysis unit, 40...update unit, P(P1,P2,...)...arrival frequency, Q(Q a ,Q b …)…branching probability, S(S1,S2,…)…sequence, T(T1,T2,…)…start time.

Claims

1. a first registration unit that registers an event tree composed of a plurality of sequences in which branches are defined by the success / failure of execution results of a series of actions to prevent the progression of an event that causes a nuclear disaster; a determination unit that identifies the initiating event that has occurred based on operation information, and determines the execution result of the action item in the corresponding event tree; an extraction unit that extracts the sequence that has a possibility of reaching an end state and a probability of releasing radioactive materials into the environment based on the determination by the determination unit; a second registration unit that registers a branch probability of whether the execution result of each of the actions is a success or failure; a calculation unit that calculates an arrival frequency to the final state in each of the extracted sequences based on the branch probability of the branch located in the action item whose execution result is undetermined; a third registration unit that registers a start time from the occurrence of the initiating event to the release of the radioactive material into the environment in each of the sequences; and a creation unit that creates a graph showing the start time and probability of the radioactive material being released into the environment, based on the start time and the arrival frequency in each of the extracted sequences.

2. 2. The nuclear emergency decision support system according to claim 1, A nuclear emergency decision support system comprising a first assessment unit for assessing the severity of a public evacuation for each of the extracted sequences based on a magnitude of the environmental release.

3. The nuclear emergency decision support device according to claim 1 or 2, A decision support device for use in a nuclear emergency, comprising a second evaluation unit that evaluates the urgency of public evacuation based on the point in time at which the time-integrated value of the arrival frequency in the graph reaches a threshold value.

4. 4. The nuclear emergency decision support device according to claim 2, further comprising: A nuclear emergency decision support device in which the severity or urgency of the public evacuation is assessed based on environmental information including at least one of meteorological information and environmental radiation information.

5. The nuclear emergency decision support device according to any one of claims 1 to 4, An apparatus for supporting decision-making in a nuclear emergency comprising an update unit that updates at least one of the registered branch probability and the start time in accordance with the situation of the nuclear disaster based on the acquired operational information.

6. A method for supporting decision-making in a nuclear emergency, the method being executed by an apparatus including a first registration unit, a determination unit, an extraction unit, a second registration unit, a calculation unit, a third registration unit, and a creation unit, A step in which the first registration unit registers an event tree composed of a plurality of sequences in which branches are defined by the execution results of success / failure in a series of actions for preventing the progression of an event causing a nuclear disaster; The determination unit identifies the initiating event that has occurred based on operation information, and determines the execution result of the corresponding action item in the event tree; extracting the sequence that has a possibility of reaching an end state and a probability of releasing radioactive materials into the environment based on the determination by the extraction unit; The second registration unit registers a branch probability of whether the execution result of each of the actions is success or failure; a step of calculating an arrival frequency to the final state in each of the extracted sequences based on the branch probability of the branch located in the action item whose execution result is undetermined, the third registration unit registering, for each of the sequences, a start time from the occurrence of the initiating event to the release of the radioactive material into the environment; and a step of generating a graph showing the start time and the probability of the radioactive material being released into the environment, based on the start time and the arrival frequency in each of the extracted sequences, by the generating unit.

7. On the computer, A step of registering an event tree composed of a plurality of sequences in which branches are defined by the success / failure of execution results of a series of actions for preventing the progression of an event that causes a nuclear disaster; Identifying the initiating event that has occurred based on operation information, and determining the execution result of the action item in the corresponding event tree; extracting the sequences that have a possibility of reaching an end state and a probability of releasing radioactive materials into the environment based on the determination; registering a branch probability of whether the execution result of each of the actions is a success or failure; calculating an arrival frequency to the final state in each of the extracted sequences based on the branch probability of the branch located in the action item whose execution result is undetermined; registering a start time from the occurrence of the initiating event to the release of the radioactive material into the environment in each of the sequences; creating a graph showing the start time and probability of the radioactive material being released into the environment, based on the start time and the arrival frequency for each of the extracted sequences.

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