Evaluation method, evaluation device, and program

Abstract

To provide an evaluation method which can evaluate the whole safety of a plurality of facilities in a case where an abnormality occurs in a part or all of the plurality of facilities, in consideration of the fact that various types of abnormalities may occur in each facility.SOLUTION: The evaluation method for evaluating the safety of an evaluation target system including a plurality of facilities, includes the steps of: setting a mode of an abnormality for each of the facilities in which the abnormality occurs in a case where an abnormality occurs in a part or all of the plurality of facilities; calculating a probability that the abnormality of the mode set for each facility occurs; and calculating a probability that abnormalities of the mode set for a part or all of the plurality of facilities occur at the same time on the basis of the probability calculated for each facility.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an evaluation method, an evaluation device, and a program. [Background technology]

[0002] Probabilistic Risk Assessment (PRA) is known as a method for evaluating the safety of a system. In PRA, various events that may occur in the system are assumed, and risk assessment is performed by taking into consideration the probability of occurrence and the impact of each event. For example, Patent Document 1 discloses a method for evaluating the risk of a fire occurring in a control panel of a nuclear power plant using PRA. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-28330 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, risk assessments using PRA are often carried out for a single facility, such as a single nuclear reactor or a single fuel storage facility. However, when multiple facilities exist on a site, it may be necessary to evaluate the risk of accidents or other abnormalities occurring simultaneously at multiple facilities. Abnormalities of various scales and types can occur at each facility, but no method has been established to evaluate the safety of multiple facilities as a whole, taking into account the differences in the abnormalities that occur at each facility.

[0005] The present disclosure provides an evaluation method, an evaluation device, and a program that can solve the above problems. [Means for solving the problem]

[0006] The evaluation method of the present disclosure is a method for evaluating safety of an evaluation target system including a plurality of facilities, the method being executed by a computer, obtaining a list of possible abnormality patterns for each of the plurality of facilities; In the event that an abnormality occurs in some or all of the above multiple facilities, The type of abnormality occurring for each of the facilities is set based on the list, and multiple patterns of abnormality across the multiple facilities are set by combining the types of abnormality set for each of the facilities. a step of calculating a probability of occurrence of the abnormality in the manner set for each facility; For each of the multiple patterns set, and calculating the probability that the abnormalities of the set type will occur simultaneously in some or all of the plurality of facilities based on the probability calculated for each facility.

[0007] The evaluation device of the present disclosure is an evaluation device for evaluating the safety of an evaluation target system including a plurality of facilities, means for acquiring a list of possible abnormality patterns for each of the plurality of facilities; In the event that an abnormality occurs in some or all of the above multiple facilities, The type of abnormality occurring for each of the facilities is set based on the list, and multiple patterns of abnormality across the multiple facilities are set by combining the types of abnormality set for each of the facilities. means for calculating the probability of occurrence of the abnormality in the manner set for each facility; For each of the multiple patterns set, and means for calculating the probability that the abnormalities of the set type will occur simultaneously in some or all of the plurality of facilities, based on the probability calculated for each facility.

[0008] The program disclosed herein is a process for evaluating the safety of an evaluation target system including a plurality of facilities, the process comprising: obtaining a list of possible abnormality patterns for each of the plurality of facilities; In the event that an abnormality occurs in some or all of the above multiple facilities, The type of abnormality occurring for each of the facilities is set based on the list, and multiple patterns of abnormality across the multiple facilities are set by combining the types of abnormality set for each of the facilities. Steps and For each of the multiple patterns set, The system executes a process including a step of calculating the probability that the abnormality of the type set for each facility will occur, and a step of calculating the probability that the abnormality of the type set for some or all of the multiple facilities will simultaneously occur based on the probability calculated for each facility. [Effects of the Invention]

[0009] According to the above-described evaluation method, evaluation device, and program, the safety of multiple facilities as a whole in the event that abnormalities occur simultaneously in some or all of the facilities can be evaluated taking into account the differences in the types of abnormalities that occur in each facility. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram illustrating an example of an evaluation device according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of an evaluation target system according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of an event tree according to the embodiment. [Figure 4] FIG. 1 is a diagram illustrating an example of a fault tree according to an embodiment. [Figure 5] FIG. 1 is a diagram showing an example of a type of accident that may occur in a facility according to an embodiment. [Figure 6] 10 is a flowchart illustrating an example of a safety evaluation process according to the embodiment. [Figure 7] FIG. 10 is a diagram showing an example of a combination of types of accidents that may occur in each facility according to the embodiment. [Figure 8] FIG. 2 is a diagram illustrating an example of a hardware configuration of an evaluation device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The safety evaluation method according to the present disclosure will be described below with reference to FIGS. <Embodiment> (composition) FIG. 1 is a block diagram showing an example of an evaluation device according to an embodiment. The evaluation device 10 evaluates the safety of a system to be evaluated, which includes multiple facilities, by calculating the probability that an abnormality such as a failure will occur simultaneously in the multiple facilities. FIG. 2 shows an example of a system to be evaluated. The system to be evaluated 100 includes facilities 1 to n and common equipment 200. For example, the system to be evaluated 100 is a nuclear facility, and the facilities 1 to n are nuclear reactors and fuel storage facilities located on the premises of the nuclear facility, and the common equipment 200 is a common power supply facility that supplies power to the facilities 1 to n. In the example of FIG. 2, only one common equipment 200 is shown, but multiple common equipment 200 may be provided. A failure of the common equipment 200 affects the facilities 1 to n, and therefore the failure of the common equipment 200 is called a common impact. When the common equipment 200 fails, the probability of an accident or the like occurring in the facilities 1 to n increases. Here, the probability that the common equipment 200 will fail is defined as P(C), and the probability that an accident will occur in facility n, provided that a failure has occurred in the common equipment 200, is defined as P(F unitn |C), the probability that an accident or the like occurs simultaneously in facilities 1 to n when the common equipment 200 is out of order can be calculated by the following formula (1). P(C)×P(F unit1 |C)×P(F unit2 |C)×···×P(F unitn |C)···(1) In PRA (Probabilistic Risk Assessment) used in safety assessment of nuclear facilities, safety assessment is based on PRA models such as event trees and fault trees, and the probability of failures or accidents occurring in facilities 1 to n and common equipment 200 can be calculated based on the PRA model. In addition, the probability of an accident occurring at each facility under the condition that a common impact occurs, P(F unitn |C) can also be calculated for each facility 1 to n based on the PRA model if common impacts are identified.

[0012] Equation (1) indicates the probability that an accident or the like will occur simultaneously at facilities 1 to n under the condition that the common equipment 200 is malfunctioning. However, in reality, the types of accidents that occur at facilities 1 to n are not uniform. For example, in one case, a major accident occurs at facility 1, while only minor accidents occur at facilities 2 to n. In another case, a minor accident occurs at facilities 1 and 2, while no accident occurs at facilities 3 to n. Various cases can occur. Furthermore, if anomalies occur at each facility, they may result in accidents of different scales and types when viewed as the entire system under evaluation 100. There are countless combinations of types of accidents that can occur simultaneously at each facility, and each combination has a different impact on the entire system under evaluation 100. Because equation (1) does not take into account the types of accidents that occur simultaneously at each facility, it is not possible to distinguish between the probability of a major accident and the probability of a minor accident occurring for the entire system under evaluation 100.

[0013] If the system under evaluation 100 is a nuclear facility and an accident releases radioactive materials, the environmental impact will vary depending on the type of accident occurring simultaneously at facilities 1 through n. The type of accident refers to, for example, the scale and type of the accident. In the case of a nuclear facility, the scale of the accident refers to the amount of radioactive material released, and the type of accident refers to, for example, the time from the occurrence of the accident until the radioactive material is released (the type of radioactive material released and the required time for surrounding residents to complete evacuation may vary depending on the time until the radioactive material is released). The type of accident is not limited to the amount of radioactive material released or the time until the release of radioactive material; other criteria related to the impact of radioactive material released from the nuclear facility can also be introduced. Regarding the safety of nuclear facilities, there is a need to more precisely analyze the impact of radioactive materials. Simply calculating the probability of simultaneous failure of facilities 1 through n under the condition that common equipment 200 is malfunctioning using the above formula (1) is insufficient to meet this need. In order to study in detail the impact of radioactive materials released from a nuclear facility (evaluation target system 100), the evaluation device 10 organizes the types of accidents that can occur simultaneously at some or all of the facilities 1 to n and their combinations from the perspective of impact, and makes it possible to calculate the probability of an accident occurring by impact. Furthermore, the evaluation device 10 calculates the probability of an accident occurring due to each combination of types of accidents that can occur at each facility.

[0014] As shown in the figure, the evaluation device 10 includes an input receiving unit 11, a calculation unit 12, an output unit 13, and a storage unit 14. The input receiving unit 11 is configured using input devices such as a keyboard, a mouse, a touch panel, buttons, etc. The input receiving unit 11 receives various information input to the evaluation device 10 using the input devices. The input receiving unit 11 outputs the received input information to the calculation unit 12 and records it in the storage unit 14. For example, the input receiving unit 11 receives settings for combinations of accident types at facilities 1 to n related to the simultaneous accident occurrence probability to be calculated.

[0015] The calculation unit 12 calculates the probability of an accident occurring according to a combination of types of accidents that may occur simultaneously at some or all of the facilities 1 to n received by the input receiving unit 11. The calculation unit 12 also calculates a list of types of accidents that may occur at each of the facilities 1 to n and their occurrence probabilities.

[0016] The output unit 13 outputs the accident occurrence probability calculated by the calculation unit 12 and a list of types of accidents that may occur in the facilities 1 to n to a display device or an electronic file. The storage unit 14 stores various information necessary for calculating the accident occurrence probability. For example, the storage unit 14 stores a PRA model for the evaluation target system 100 (for example, an event tree or a fault tree for each of facilities 1 to n), various information received by the input receiving unit 11, and the like.

[0017] FIG. 3 shows an example of an event tree according to an embodiment. The event tree 300 in FIG. 3 models the progression of events that occur after a specific initiating event occurs at facility x (x: 1 to n). The headings of the event tree 300 list initiating events and mitigation measures 1 to 4.... Mitigation measures 1 to 4... indicate devices or operations that mitigate the progression of an event. If the mitigation measures are successful, they can prevent or suppress the progression of the event. If the mitigation measures fail, the event progresses to a more serious event. For example, if an accident occurs at a nuclear facility and operations are shut down, the decay heat of the nuclear fuel must be removed. The amount (scale) and type (timing) of radioactive material released will change depending on whether the operation (mitigation measures 1 to 4...) is successful. The event tree 300 in FIG. 3 illustrates the relationship between the success or failure of mitigation measures 1 to 4... and the progression of the event. In the event tree 300, at the branching points of mitigation measures 1 to 4, success is represented by a horizontal line and failure is represented by a vertical line. For example, if mitigation measures 1, 2, and 3 are successful and then mitigation measure 4 fails, an accident of magnitude a (No. = 2) occurs at facility x. If mitigation measure 1 fails and mitigation measures 2 to 4 are successful, an accident of magnitude f (No. = 8) occurs at facility x. Since event trees such as those shown in Figure 3 are used for safety assessments of nuclear facilities, event trees are prepared for facilities 1 to n. Using the event tree for each facility, it is possible to calculate the type of accident that may occur at facilities 1 to n. Note that the scales a to f shown in Figure 3 are merely examples, and the scale (amount of radioactive material released) can be classified into any number of levels. For example, if scale a and scale d are similar, they may be grouped together as scale A.

[0018] FIG. 4 shows an example of a fault tree according to the embodiment. A fault tree is a model that uses a tree structure to represent the relationship between combinations of base events that cause a top event. As an example, FIG. 4 shows a fault tree 400 related to "Mitigation Measure 1" illustrated in FIG. 3. In the fault tree 400, "equipment failure," "common equipment failure," "equipment A failure," "equipment B failure," and "abnormality 1" to "abnormality 6" are base events, and "failure of mitigation measure 1" is the top event. The fault tree 400 indicates that "failure of mitigation measure 1" occurs when "equipment failure" and "common equipment failure" occur; "equipment A failure" and "equipment B failure" occur; "abnormality 1" or "abnormality 2" causes "common equipment failure." Here, the common equipment is the common equipment 200 in FIG. 2, and equipment A and equipment B are equipment installed in facility x. Furthermore, for each base event in the fault tree 400, an occurrence probability of that base event is set based on the knowledge and analysis results of engineers. This makes it possible to calculate, for example, the occurrence probability of "failure of mitigation measure 1" or the failure probability of the common equipment 200. Furthermore, the storage unit 14 stores a fault tree whose top events are the events (mitigation measures 1 to 4, etc.) shown in the headings after the initiating event in the event tree 300 in FIG. 3. Based on the occurrence probability set for each base event in these fault trees and the tree structure of the fault tree, the success probability and failure probability of each branch in the event tree 300 in FIG. 3 can be calculated. Based on the success probability and failure probability of each branch, the occurrence probability of the final states No. 1 to No. 8 shown in FIG. 3 can be calculated.

[0019] The event tree and fault tree shown in Figures 3 and 4 are for facility x. However, since similar PRA models are prepared for facilities 1 to n, the probability of occurrence of all possible accident scenarios at each facility can be calculated for each of facilities 1 to n. Figure 5 shows an example of possible accident scenarios at each facility. The calculation results of the accident scenarios shown in Figure 5 illustrate that facility 1 can experience accidents of various magnitudes a to c, and times a to b, and that other facilities 2 to n can experience accidents of similar magnitude to facility 1. In the example shown in Figure 5, the same accident scenario occurs at each facility, but the accident scenarios that can occur at each facility may differ. Furthermore, while the event tree 300 in Figure 3 shows an example of associating the progression of events with the scale of the accident, the type of accident that can occur at each facility (the timing of the release of radioactive materials), such as time a (e.g., immediately after the accident), time b (three days after the accident), etc., may also be calculated from the event tree. Furthermore, as described above, the occurrence probability of each type of accident can be calculated from the event tree and fault tree.

[0020] For example, the calculation unit 12 may calculate a list of possible accident types and their occurrence probabilities for each facility, as illustrated in FIG. 5, based on the PRA model (event tree, fault tree) stored in the storage unit 14. Alternatively, the output unit 13 may display the PRA model on a display device, and a user may identify a list of possible accident types at each facility based on the displayed PRA model and calculate the occurrence probabilities for each type. The accident types and occurrence probabilities may be calculated based on a list of combinations of accident types and basic events leading to the accidents, which are calculated in advance based on the PRA model. The calculations are not limited to calculations based on event trees or fault trees, and may be based on other data. The accident types are not limited to the amount or timing of release of radioactive materials, and may be other indicators related to the impact of radioactive materials released from the evaluation target system 100.

[0021] (operation) Next, an example of the operation of the evaluation device 10 will be described with reference to FIG. FIG. 6 is a flowchart showing an example of a safety evaluation process (a process for calculating the probability of accidents occurring simultaneously at multiple facilities) according to the embodiment. First, a common influence factor is identified (step S1). For example, a user inputs information identifying the shared equipment 200 as a common influence factor (e.g., identification information of the shared equipment 200) to the evaluation device 10. The input receiving unit 11 acquires the input information identifying the shared equipment 200 and records it in the memory unit 14. Next, the calculation unit 12 calculates the probability of the common influence occurring (step S2). For example, if multiple pieces of shared equipment 200 are installed, the calculation unit 12 calculates the probability of the shared equipment 200 failing by multiplying the failure occurrence probabilities of the shared equipment 200 stored in the memory unit 14. The calculation unit 12 records the calculation result in the memory unit 14. Note that the probability of the common influence occurring may be calculated by an external computer or the like and input to the evaluation device 10. In this case, the input receiving unit 11 acquires the occurrence probability of the input common influence and records it in the memory unit 14.

[0022] Next, the calculation unit 12 calculates the type of accident that may occur for each facility (step S3). For example, the calculation unit 12 calculates, for each facility 1 to n, a list of types of accidents that may occur at each facility, based on an event tree related to accidents that may occur at each facility, which is stored in the storage unit 14. The calculation unit 12 records the calculated list of types of accidents (FIG. 5) in the storage unit 14. Note that the list of types of accidents that may occur at each facility may be calculated by an external computer or the like and input to the evaluation device 10. In this case, the input receiving unit 11 acquires the input list information and records it in the storage unit 14.

[0023] Next, a combination of accident types is set (step S4). For example, a user selects a combination of accident types whose occurrence probability is to be determined based on the impact of radioactive materials, and inputs the selected combination of accident types to the evaluation device 10. For example, if a user wants to know the probability of an accident in which a large amount of radioactive materials is released (large scale) from the evaluation target system 100, the user identifies combinations of accident types at facilities 1 to n that are expected to lead to an accident of that scale, and inputs the combinations to the evaluation device 10. The input receiving unit 11 acquires information on the input combination of accident types to be evaluated, and records the information in the storage unit 14. An example of a combination of accident types is shown in FIG. 7. For example, the combination No. 1 in FIG. 7 is a combination that is expected to result in a large amount of radioactive materials being released from the nuclear facility. Similarly, No. 2 and No. 3 are combinations that, on the condition that the common equipment 200 fails, further stipulate that accidents of scale b and scale c will occur simultaneously at facilities 1 to n, respectively. For example, the combinations No. 2 and No. 3 are combinations of accident types in which the amount of radioactive material released from the nuclear facility is expected to be medium and small, respectively. The combinations No. 4 and No. 5 are examples of combinations in which accidents of different scales will occur at facilities 1 to n, on the condition that the common equipment 200 fails. For example, the combination No. 4 stipulates that an accident of scale c will occur at facilities 1 and 2, and an accident of scale b will occur at facilities 3 to n. The combination No. 6 is an example of a combination in which, on the condition that the common equipment 200 fails, accidents will occur simultaneously at only some of facilities 1 to n. For example, the combination No. 6 stipulates that an accident of scale a will occur at facility 1, an accident of scale b will occur at facility 2, and no accident will occur at facilities 3 to n. The combinations No=7 and 8 are combinations that stipulate that accidents will occur simultaneously in facilities 1 to n, with the timing of the release of radioactive materials at times a and b, respectively, on the condition that the common equipment 200 fails. The combination No=9 is a combination that stipulates that accidents will occur simultaneously in facilities 1 to n, with the scale a and the release timing being time a, on the condition that the common equipment 200 fails.The combination No=10 is a combination that determines that the common equipment 200 does not break down, an accident of magnitude a occurs at facilities 1 and 2, and an accident of time a occurs at facilities 3 to n simultaneously.

[0024] Next, the calculation unit 12 calculates the probability of an accident occurring under the condition that the common impact occurs (step S5). For example, for facility x, the calculation unit 12 calculates the failure probability of mitigation measure 1 under the condition that the common equipment 200 is faulty, based on the fault tree 400 stored in the storage unit 14. The calculation unit 12 also calculates the failure probability of other mitigation measures under the condition that the common equipment 200 is faulty, and calculates the probability of accidents of scales a to f based on the event tree 300. For each of facilities 1 to n, the calculation unit 12 calculates the probability of accident occurrence for each scale, such as scale a to scale c, and the probability of accident occurrence for each release timing, such as time a to time b. The calculation unit 12 records the calculation results in the storage unit 14. Note that the probability of an accident occurring under the condition that the common impact occurs may be calculated based on a list of combinations of failures that lead to accidents, which is calculated in advance by an external computer or the like based on the event tree and fault tree. In this case, the input reception unit 11 acquires the list of combinations of failures that lead to accidents and records it in the storage unit 14. In this way, if the combination of failures that will lead to an accident is calculated in advance, the probability of an accident occurring under conditions in which a common event occurs can be calculated simply by substituting the probability of failure occurrence (probability 1 for the probability of a common event occurring, and the probability of occurrence used in PRA for other failures).

[0025] Next, the calculation unit 12 calculates the probability of simultaneous accidents occurring in multiple facilities (step S6). For example, the probability that the common equipment 200 breaks down is P(C), and the probability that an accident of magnitude a occurs in facility x under the condition that the common equipment 200 breaks down, calculated in step S5, is P(F unitx、a |C), the probability that an accident of magnitude a occurs simultaneously in facilities 1 to n when the common equipment 200 is out of order can be calculated by the following equation (2). P(C)×P(F unit1、a |C)×P(F unit2、a |C)×···×P(F unitn、a |C)···(2) The calculation unit 12 calculates the occurrence probability for the combination No.=1 (No.=1 in FIG. 7) set in step S4 using the above formula (2).

[0026] Similarly, the calculation unit 12 calculates the occurrence probabilities for No=2 and 3 in FIG. 7 using the following equations (3) and (4), respectively. P(C)×P(F unit1、b |C)×P(F unit2、b |C)×···×P(F unitn、b |C)···(3) P(C)×P(F unit1、c |C)×P(F unit2、c |C)×···×P(F unitn、c |C)···(4)

[0027] Furthermore, the calculation unit 12 calculates the occurrence probabilities for No. 4 and No. 5 in FIG. 7 using the following equations (5) and (6). P(C)×P(F unit1、c |C)×P(F unit2、c |C)×P(F unit3、b |C)×···×P(F unitn、b |C)···(5) P(C)×P(F unit1、c |C)×P(F unit2、a |C)×···×P(F unitn、a |C)···(6)

[0028] Furthermore, the calculation unit 12 calculates the occurrence probability for No=6 in FIG. 7 using the following equation (7). P(C)×P(F unit1、a |C)×P(F unit2、b |C) × probability that an accident does not occur at facility 3 under the condition that a failure occurs in common equipment 200 × × probability that an accident does not occur at facility n under the condition that a failure occurs in common equipment 200 (7) The calculation unit 12 calculates the probability that an accident will not occur in facility y (y=3 to n) under the condition that a failure occurs in the common equipment 200 in equation (7) using a calculation formula such as the following equation (8). 1-(P(F unity、a |C)+P(F unity、b |C)+P(F unity、c |C)))···(8) However, in equation (8), for the sake of convenience of explanation, the types of accidents that can occur at facility y (y=3 to n) are limited to accidents of scales a to c.

[0029] In a similar way, the calculation unit 12 calculates the accident occurrence probability according to the combination of accident modes that may occur at each facility for No. 7 to 10 in FIG.

[0030] Next, the output unit 13 outputs the calculation results of the simultaneous accident occurrence probability at multiple facilities recorded in the storage unit 14 (step S7). For example, in step S6, the output unit 13 outputs the accident occurrence probability calculated for each combination of accident types No. 1 to 10 in FIG. 7 to a display device or the like. This allows the user to understand the accident occurrence probability for each combination of accident types to be evaluated set in step S4. For example, if multiple combinations of accident types that are expected to lead to large-scale accidents are set, the probability of a large-scale accident occurring can be understood for each combination of accident types.

[0031] In the flowchart of Fig. 6, the timing of the accident patterns to be evaluated is set in step S4, but the calculation unit 12 may generate combination information that comprehensively combines all accident patterns that can occur at each of the facilities 1 to n, and calculate the probability of simultaneous accidents occurring at multiple facilities for all patterns based on the generated combination information. Also, as shown by No. 10 in Fig. 7, the probability that some or all of the facilities 1 to n will fail simultaneously when the common equipment 200 does not fail may be calculated. In this case, in step S5, the probability of an accident occurring at each of the facilities 1 to n under conditions in which no common influence occurs is calculated, and in step S6, the probability of simultaneous accidents occurring is calculated using the result and the probability that no common influence occurs.

[0032] (effect) As described above, according to this embodiment, accidents occurring at each facility are classified according to the type of accident (scale and type), and combination patterns of accident types that can occur at each facility are set according to the evaluation objective. The accident occurrence probability is calculated for each set combination pattern. This allows the safety of multiple facilities as a whole to be evaluated in the event of simultaneous abnormalities occurring in some or all of the facilities, taking into account the possibility of various types of abnormalities occurring at each facility. For example, if the evaluation target system 100 is a nuclear facility, the amount of radioactive material released and the time until the release are significant in the event of an accident involving the release of radioactive material (e.g., affecting whether surrounding residents can evacuate in time). Therefore, the evaluation objective is to understand the risk according to the impact of radioactive material released from the evaluation target system 100, and accident types (scale = release amount, type = release timing) that are useful for classification from the perspective of environmental impact are defined. Then, appropriate combination patterns of accident types are set for each facility, and combination patterns are created according to the impact of radioactive material released from the evaluation target system 100. For example, combination patterns are created for each expected level of impact, such as combination patterns of failure modes that occur simultaneously at each facility that are expected to result in a large amount of radioactive material being released from the entire nuclear facility (i.e., that are expected to have a large impact on the environment), combination patterns of failure modes that occur simultaneously at each facility that are expected to have a relatively small impact on the environment, etc. Then, by calculating the accident occurrence probability for each combination pattern of accident modes that has been created, it becomes possible to evaluate the occurrence probability of simultaneous accidents according to the level of impact on the environment.

[0033] FIG. 8 is a diagram illustrating an example of a hardware configuration of the evaluation device according to the embodiment. The computer 900 includes a CPU 901, a main memory device 902, an auxiliary memory device 903, an input / output interface 904, and a communication interface 905. The evaluation device 10 described above is implemented in the computer 900. The above-described functions are stored in the auxiliary memory device 903 in the form of a program. The CPU 901 reads the program from the auxiliary memory device 903, loads it into the main memory device 902, and executes the above-described processing in accordance with the program. The CPU 901 also allocates a storage area in the main memory device 902 in accordance with the program. The CPU 901 also allocates a storage area in the auxiliary memory device 903 for storing data being processed in accordance with the program.

[0034] A program for implementing all or part of the functions of the evaluation device 10 may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed to perform processing by each functional unit. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, if a WWW system is used, the term "computer system" also includes a homepage provision environment (or display environment). Furthermore, the term "computer-readable recording medium" refers to portable media such as CDs, DVDs, and USBs, as well as storage devices such as hard disks built into the computer system. Furthermore, if the program is distributed to the computer 900 via a communication line, the computer 900 that receives the program may load the program into the main storage device 902 and execute the above-described processing. Furthermore, the program may be for implementing part of the above-described functions, or may be capable of implementing the above-described functions in combination with a program already stored in the computer system.

[0035] As described above, several embodiments according to the present disclosure have been described, but all of 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, and modifications 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 as defined in the claims, as well as in the scope and spirit of the invention.

[0036] <Additional Notes> The evaluation method, evaluation device, and program described in each embodiment can be understood, for example, as follows.

[0037] (1) The evaluation method according to the first aspect is a computer-implemented evaluation method for evaluating the safety of a system to be evaluated that includes a plurality of facilities, and includes the steps of: in the case where an abnormality occurs in some or all of the plurality of facilities, setting the abnormality type for each facility in which the abnormality occurs (S4); calculating the probability that the abnormality of the type set for each facility will occur (S5); and, based on the probability calculated for each facility, calculating the probability that the abnormality of the type set for some or all of the plurality of facilities will occur simultaneously (S6). This allows the safety of multiple facilities as a whole to be evaluated in the event that abnormalities occur simultaneously in some or all of the facilities, taking into account the possibility that various types of abnormalities may occur in each facility.

[0038] (2) The evaluation method according to the second aspect is the evaluation method of (1), wherein the system to be evaluated has one or more common pieces of equipment that affect some or all of the facilities, and further comprises a step of identifying the common equipment and a step of calculating the failure probability of the identified common equipment, wherein the step of calculating the probability of occurrence of the abnormality in the aspect set for each facility calculates a conditional probability, which is the probability that the abnormality will occur for each facility under conditions in which the common equipment is faulty, and the step of calculating the probability of simultaneous occurrence multiplies the failure probability of the common equipment by the conditional probability for each facility to calculate the probability of simultaneous occurrence of the abnormalities in the aspect set for some or all of the facilities. For example, if there is a factor that commonly affects multiple facilities, a malfunction of the common factor may cause an accident or the like to occur simultaneously at the multiple facilities. According to the second aspect, it is possible to calculate the probability that an abnormality will occur simultaneously in some or all of the multiple facilities, provided that a malfunction of the common factor occurs.

[0039] (3) The evaluation method according to the third aspect is the evaluation method according to (1) to (2), wherein the abnormality state is the scale of the abnormality occurring in the facility and / or the form of the abnormality occurring in the facility. This makes it possible to calculate the probability of an anomaly occurring in each facility depending on the scale and type of anomaly.

[0040] (4) The evaluation method according to the fourth aspect is the evaluation method according to any one of (1) to (3), wherein the aspect of the abnormality is the amount of radioactive material released from the facility and / or the timing of the release of radioactive material from the facility. This makes it possible to calculate the probability of an abnormality occurring depending on the amount and timing of radioactive material released from each facility when multiple facilities are nuclear-related.

[0041] (5) The evaluation method according to the fifth aspect is the evaluation method of (1) to (4), wherein in the step of setting the type of abnormality, the type of abnormality is set for each facility according to the degree of impact of radioactive materials released from the system to be evaluated. By defining the type of accident based on the impact of radioactive materials, it is possible to classify the severity and nature of accidents from perspectives other than the amount and timing of release of radioactive materials, and to evaluate safety according to that classification.

[0042] (6) The evaluation method according to the sixth aspect is the evaluation method of (1) to (5), further comprising a step of calculating the type of abnormality that may occur in the facility based on an event tree that represents the progression of events from an initiating event occurring in the facility to an abnormality that ultimately occurs, and in the step of setting the type of abnormality for each facility, the type of abnormality is set for each facility based on the type of abnormality calculated in the step of calculating the type of abnormality. Probabilistic risk assessment is performed for nuclear facilities, and the types of accidents that can occur can be calculated and listed based on the event tree used in the assessment.

[0043] (7) An evaluation method according to a seventh aspect is an evaluation device 10 for evaluating the safety of a system to be evaluated that includes a plurality of facilities, and includes: a means (input receiving unit 11) for setting the type of abnormality for each facility in which the abnormality occurs when an abnormality occurs in some or all of the plurality of facilities; a means (calculation unit 12) for calculating the probability of the abnormality of the type set for each facility occurring; and a means (calculation unit 12) for calculating the probability of the abnormality of the type set for some or all of the plurality of facilities occurring simultaneously, based on the probability calculated for each facility.

[0044] (8) The program according to the eighth aspect causes a computer 900 to execute a process for evaluating the safety of a system under evaluation that includes multiple facilities, in which, in the event that an abnormality occurs in some or all of the multiple facilities, the program includes the steps of: setting the type of abnormality for each facility in which the abnormality occurs; calculating the probability that the abnormality of the type set for each facility will occur; and calculating the probability that the abnormalities of the type set for some or all of the multiple facilities will simultaneously occur based on the probability calculated for each facility. [Explanation of symbols]

[0045] 10. Evaluation device 11 Input reception section 12...Calculation section 13. Output section 14...Storage section 900···Computer 901 CPU 902...Main memory 903...Auxiliary storage device 904 Input / Output Interface 905···Communication Interface

Claims

1. 1. A computer-implemented evaluation method for evaluating safety of a system to be evaluated that includes multiple facilities, comprising: obtaining a list of possible abnormality patterns for each of the plurality of facilities; a step of setting a type of abnormality occurring in each of the plurality of facilities based on the list in the event that an abnormality occurs in some or all of the plurality of facilities, and setting a plurality of patterns of abnormality types occurring in all of the plurality of facilities by combining the types of abnormality set for each of the facilities; calculating a probability that the abnormality of the type set for each facility will occur; calculating a probability that the abnormalities of the set type will simultaneously occur in some or all of the plurality of facilities based on the probability calculated for each of the set plurality of patterns for each of the facilities; An evaluation method having the following characteristics.

2. the system to be evaluated has one or more common facilities that affect a part or all of the plurality of facilities; identifying the common equipment; calculating the failure probability of the identified common equipment; and In the step of calculating the probability of occurrence of the abnormality in the aspect set for each facility, a conditional probability is calculated, which is the probability that the abnormality will occur for each facility under a condition in which the common equipment is broken, In the step of calculating the probability of simultaneous occurrence, the probability of simultaneous occurrence of the abnormalities of the set type in some or all of the plurality of facilities is calculated by multiplying the failure probability of the common equipment by the conditional probability for each of the facilities. The evaluation method according to claim 1 .

3. The mode of the abnormality is the scale of the abnormality occurring at the facility and / or the form of the abnormality occurring at the facility. The evaluation method according to claim 1 or 2.

4. The aspect of the abnormality is the amount of radioactive material released from the facility and / or the timing of the release of radioactive material from the facility. The evaluation method according to claim 1 or 2.

5. In the step of setting the type of abnormality, the type of abnormality is set for each facility according to the degree of influence of radioactive materials released from the evaluation target system. The evaluation method according to claim 1 or 2.

6. Calculating the type of the abnormality that may occur in the facility based on an event tree that represents the progression of events from an initiating event occurring in the facility to an abnormality that ultimately occurs; and In the step of obtaining the list, the list is obtained based on the type of abnormality for each of the plurality of facilities calculated in the step of calculating the type of abnormality based on the event tree for each of the plurality of facilities. The evaluation method according to claim 1 or 2.

7. An evaluation device for evaluating the safety of an evaluation target system including a plurality of facilities, means for acquiring a list of possible abnormality patterns for each of the plurality of facilities; a means for setting a type of abnormality occurring in each of the plurality of facilities based on the list in the event that an abnormality occurs in some or all of the plurality of facilities, and for setting a plurality of patterns of abnormality patterns for all of the plurality of facilities by combining the types of abnormality set for each of the facilities; means for calculating the probability of occurrence of the abnormality in the manner set for each facility; a means for calculating a probability that the abnormalities of the set type will simultaneously occur in some or all of the plurality of facilities based on the probability calculated for each of the set plurality of patterns for each of the facilities; An evaluation device having:

8. On the computer, A process for evaluating the safety of a system to be evaluated that includes a plurality of facilities, obtaining a list of possible abnormality patterns for each of the plurality of facilities; In the case where an abnormality occurs in some or all of the plurality of facilities, a type of the abnormality occurring in each of the facilities is set based on the list, and a plurality of patterns of abnormality types in all of the plurality of facilities are set by combining the types of abnormality set for each of the facilities; calculating a probability that the abnormality of the type set for each facility will occur; calculating a probability that the abnormalities of the set type will simultaneously occur in some or all of the plurality of facilities based on the probability calculated for each of the set plurality of patterns for each of the facilities; A program that executes a process having the above steps.

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