KR101788387B1 - Assessment system and method for vital area identification using probabilistic safety assessment fault tree in nuclear power plant - Google Patents

Abstract

The present invention relates to a core zone evaluation system for deriving a response scenario in the case of a core damage in a nuclear power plant, comprising a radioactive information confirmation unit for checking whether a radioactive material is leaked, an area where a system of a nuclear power plant core is located, A main zone in which there is at least one system in which radioactive material can leak out by at least one of the natural disasters and any one that must be defended in order to be able to resolve the initial events, And a main zone analysis unit for analyzing at least one of sabotage behavior and natural disaster in the main zone by the malfunctioning tree, Is generated and the corresponding zone is damaged, And evaluating the core area which is the area to be caused. Also, in the method of evaluating the core area in the nuclear power plant, the step of preparing the nuclear facility information, calculating the core damage frequency based on the nuclear facility information, checking the inventory amount of the radioactive material using the calculated core damage frequency, Determining whether the corresponding scenario is a probabilistic safety assessment (PSA) logical model, transforming it into a sabotage fault tree based on the judgment, based on sabotage fault trees Determining a set of defenses that must be protected to prevent radiation sabotage and a set of attacks that must be approached in order to produce a radioactive sabotage; and selecting a core zone as a priority of the defense set, How to reinforce the selected core areas here The step of reinforcing the physical protection to be achieved by further comprising.

Description

TECHNICAL FIELD The present invention relates to a system and a method for evaluating a critical zone using a fault tree in a nuclear power plant, and a system and a method for evaluating a critical zone using a fault tree.

The present invention relates to a critical zone evaluation system using a stochastic safety evaluation fault tree in a nuclear power plant and a method thereof.

Recently, physical protection has been strengthened in various ways in order to prevent damage caused by terrorism or sabotage to nuclear power plants. One such technique is the probabilistic safety assessment technique for selecting and protecting critical areas. This can be used to derive essential equipment during normal operation of a nuclear power plant, and it is possible to systematically identify core areas by converting these devices into corresponding zones. It is also possible to conduct intentional malicious acts such as terrorism or sabotage, It is possible to analyze where the equipment, systems and facilities are installed, which may directly or indirectly affect health and safety.

Conventionally, when designing a nuclear power plant, it is necessary to design the core zone setting which can cause irreversible radiation effects, such as terrorism, sabotage, extreme disaster, explosion or fire, Or manual, it was not possible to identify key areas that could prevent core damage due to machine failure.

In addition, the conventional security response scenario evaluation system can not accurately derive the core damage scenario by sabotage, and there is a limitation that the initial event that threatens the design standard and the logic model that can cause direct radiation sabotage are not presented.

Korean Public Release No. 2013-0111365 (published Feb. 27, 2015)

Accordingly, an object of the present invention is to provide a core zone evaluation system using a stochastic safety evaluation fault tree in a nuclear power plant and a method thereof.

It is an object of the present invention to provide a core zone evaluation system for deriving a corresponding scenario in case of core damage in a nuclear power plant, which comprises a radioactive information confirmation unit for checking whether radioactive material is leaked, a zone where a system of a nuclear power plant core is present, And at least one of the natural disasters must defend the main areas where there is one or more systems where the radioactive material may leak to the outside and the initial events which are all abnormal events that cause the nuclear power plant to stop, And a main zone analysis unit for analyzing at least one of the natural disasters and the behavior of the sabotage in the main zone by means of the fault tree, wherein the malicious An initial event occurs as a result of the action, If so, it is accomplished by evaluating the core area which is the area where the core damage is caused.

 The main zone analysis unit may include a processor including a logical model algorithm for scenarios in which an initial event may cause radiation sabotage alone or in combination with other malicious behavior.

The processor may include a probabilistic safety assessment internal event model for analyzing the damage of the core in the event of a major accident, and an external event judgment model for determining the probability of the facility being destroyed by at least one of fire, flooding, and explosion.

In the internal event model of the probabilistic safety assessment, the internal events may include at least one of reactor coolant loss accident, loss of power to the offsite power plant, large secondary pipe breakage, secondary water supply loss accident, or condenser vacuum loss accident.

The main area analysis department classifies the area where the nuclear plant core is located as a target analysis module that classifies the area where the enemy forces must attack to generate sabotage and a defensive area that must be protected to prevent sabotage Defense analysis module.

The main zone analysis unit classifies the zone into zones that cause core damage by sabotage for a single zone and sabotage for combinations of two or more zones using the data of the target analysis module, And a zone evaluation module for selecting zones.

Further, in the method of evaluating the core zone in the nuclear power plant of the present invention, the step of preparing the nuclear facility information, the core damage frequency is calculated based on the nuclear facility information, and the stock amount of the radioactive material is checked using the calculated core damage frequency Determining whether the corresponding scenario is a probabilistic safety assessment (PSA) logic model, transforming it into a sabotage fault tree based on the judgment, a sabotage fault tree Determining a set of defenses that must be protected to prevent radiation sabotage and a set of attacks that must be approached in order to generate a radiation sabotage based on the defensive set, and selecting a core zone with priority among the defensive set.

In the case of the PSA logic model, it is necessary to secure the internal event probabilistic safety assessment (PSA) logic model by sabotage, to secure the secured PSA logic model in the fire, Generating a database by integrating with at least one external event judgment model, and converting the sabotage fault tree into a sabotage fault tree through the generated database.

If it is not a probabilistic safety assessment (PSA) logic model, it is necessary to select the initial sabotage case, to analyze the sabotage incident occurrence of the selected initial event, and to create the fault tree of the sabotage case .

In addition, a method of reinforcing core zones to physically protect core areas in a nuclear power plant includes steps of preparing the nuclear facility information, calculating the core damage frequency based on the nuclear facility information, and using the calculated core damage frequency, Determining whether the corresponding scenario is a probabilistic safety assessment (PSA) logic model when the radiation is exposed, converting it into a sabotage fault tree based on the judgment, Determining the set of defenses that must be protected to prevent the set of attacks and the radiation sabotage that must be approached in order to generate a radiation sabotage based on the sabotage fault tree, the step of selecting the critical zone with priority among the defensive set, To protect them physically. .

In the case of the PSA logic model, it is necessary to secure the internal event probabilistic safety assessment (PSA) logic model by sabotage, to secure the secured PSA logic model in the fire, Generating a database by integrating with at least one external event judgment model, and converting the sabotage fault tree into a sabotage fault tree through the generated database.

If it is not a probabilistic safety assessment (PSA) logic model, it is necessary to select the initial sabotage case, to analyze the sabotage incident occurrence of the selected initial event, and to create the fault tree of the sabotage case .

According to the present invention, a core zone evaluation system using a stochastic safety assessment fault tree and a method thereof are provided in a nuclear power plant.

1 illustrates a core zone evaluation system of a nuclear power plant according to an embodiment of the present invention.
2 illustrates a logical model algorithm according to an embodiment of the present invention through a fault tree.
Figure 3 illustrates a core zone assessment process in accordance with an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the technical concept of the present invention, are incorporated in and constitute a part of the specification, and are not intended to limit the scope of the present invention.

1 illustrates a core zone evaluation system of a nuclear power plant according to an embodiment of the present invention. The core zone evaluation system of the nuclear power plant comprises a radioactive information verification unit 100, a zone classification unit 200, and a main zone analysis unit 300.

The radioactive information verifying unit 100 can check whether or not the radioactive material is leaked. The radioactive information verifying unit 100 can determine whether or not the radioactive material is leaked by checking the inventory amount of the radioactive material.

In an embodiment of the present invention, the radioactive information verifying unit 100 can determine whether the core of the reactor core is damaged by sabotage, that is, the core damage frequency (CDF), which is the probability of core damage.

In the embodiment of the present invention, the CDF value of the risk of sabotage can be set to a value of 1.0E-04 / yr. If the CDF value is 1.0E-04 / yr or more, that is, if the radioactive material is exposed more than once every 10,000 years, it is judged that the radioactive material is damaged due to damage of the core, and 1.0E-04 / yr , It can be judged that the core is not damaged and the inventory amount of the radioactive material is maintained.

The zone classification unit 200 includes a main zone in which there is at least one system in which the radioactive material can leak to at least one of the behavior of the sabotage and the natural disaster, All abnormal events that cause plant shutdowns are classified as hazardous areas where there is one or more systems that must be defended to allow initial events to be resolved. Hazardous areas are areas where there is a system necessary to mitigate an initial event that occurs beyond the capability of the nuclear power plant accident mitigation system.

In this case, the initial event means all abnormal events that cause the shutdown of the plant by causing the transient phenomenon in the nuclear plant, and it is the basic information for constructing the event tree in the Probabilistic Safety Assessment (PSA).

Herein, in the present specification, when an initial event occurs due to a malicious act in a dangerous area, and the corresponding zone is damaged, the zone causing the core damage is referred to as a core zone.

The main zone analysis unit 300 can analyze the behavior of the radioactive material in the main zone that can be leaked as a fault tree. The main zone analysis unit 300 includes a processor 310, a target analysis module 320, a defense analysis module 330, and a zone evaluation module 340.

The processor 310 includes a probabilistic safety assessment internal event model for analyzing whether the core is damaged in the event of a major accident, and an external event judgment model for determining the possibility of damage to the facility due to fire or flooding.

As one embodiment of the present invention, the types of internal events in the internal event model include the initial events LOCA (Loss of Coolant Accident), LOS (Loss of Offset Power) Large Steam Supp; Break (LSSB), Loss of Feed Water (LOFW), and Loss of Condenser Vaccum (LOCV).

The external event judgment model stores information on the probability of occurrence of core damage in a nuclear power plant because sabotage caused by at least one of fire, flood, and explosion can not be used in all the compartments in the compartment. This may be assessed as the loss of the compartment when all of the devices in the compartment are unavailable due to fire, flooding and explosion in the sabotage model at the time of evaluation of the core zone.

Processor 310 includes a logic model algorithm for scenarios in which an initial event can cause radiation sabotage alone or in combination with other malicious behavior. The logical model algorithm will be described in detail with reference to FIG.

Figure 2 shows the logical model algorithm as a fault tree. Loss of reactor coolant accident (LOCA), Loss of offsit power of power plant, Large steam supp; y break of LSSB, Loss of secondary water supply accident Loss of Condenser Vaccum (LOFW) and Loss of Condenser Vaccum (LOCV) represent early events that can cause core damage due to malicious attacks.

In fault trees, accident mitigation systems and auxiliary systems that damage the core are modeled, and if an initial event occurs due to sabotage, failure of the equipment failure results in loss of reactor cooling and core damage.

Referring to FIG. 2, each initial event includes System 1 and System 2, which may show core damage only when both systems are damaged for each initial event. That is, if either system 1 or system 2 is damaged, core damage is not achieved.

In addition, each system includes compartment 1 and compartment 2, each compartment containing a machine, pump, and valve, and this compartment is also damaged only when both compartments are damaged.

In this way, the system and the compartment are made for each initial event, and even if each initial event occurs, the core damage can be determined by mutual combination by the compartment and the system.

Also, in the failure tree of the PSA Logic Model, replace the Device Basic Event with a zone (compartment) to change to a zone that causes damage to the device in the event of an external malicious attack or sabotage.

The target analysis module 320 categorizes attack aggregation areas that must be approached by hostile forces to generate sabotage.

The sabotage model is a compilation of basic events consisting of devices that are converted into compartments. It computes a set of minimum disjoint sets of attacks (Target Sets) that will cause core damage in case of sabotage success.

At this time, each minimum set of disjuncts, which is a zone, categorizes the target set into a minimum set of disjoints of the zone where the enemy forces can attack if the attack is carried out.

The defense analysis module 330 classifies defensive areas that must be protected to prevent radiation sabotage. The defense analysis module 330 may perform a defense set analysis process to classify the defense areas.

A Prevention Set is a combination of spaces that must be protected to prevent radiation sabotage. The defensive set includes at least one zone in each Target Set. If the hostile forces are not accessible from any zone of the defensive set, none of the sabotage scenarios represented by sabotage failure trees will be successful.

Each set of defenses includes the minimum system, human factor, and equipment that can block the radiation sabotage if the compartment is protected. As shown in the table below, if one of the defense sets in each of the cities is selected and protected completely, it is impossible to release the radiation by sabotage.

Table 1 compares these combinations of codes in the defense analysis module according to the embodiment of the present invention.

As shown in Table 1, a code consisting of numbers and capital letters in each row and column is shown as a code for each system or compartment combination that does not cause core damage due to minimal defenses during sabotage accidents.

Here, in Table 1, column no. 1 to No. Numeral 192 denotes a combination of the number of compartments. 1 to No. 1,341 represents the number of combinations. If you look at the code that combines each row and column, the numbers from the left to the third are the height of each zone (feet-ground level) in the plain, the first letter after the hyphen (-) Is the containment building, T is the turbine building, and Y is the yard. The next two digits represent the compartment number, and the last capital letter represents any of the compartments A through D.

About 120,000 of these codes are generated, but are not limited to these.

The zone evaluation module 340 uses the data of the target analysis module to evaluate zones to cause core damage by sabotage for a single zone and sabotage for two zone combinations to determine core zones to protect Can be selected.

In particular, divide zones that cause core damage by sabotage for a single zone, such as a containment building or main control room, as a Level 1 core zone. This will cause reactor core damage even if only one zone is damaged. Nuclear Power Plant Off-grid power systems and emergency diesel generators are classified as Level 2 core zones if they are simultaneously hit by sabotage and are lost. That is, simultaneous damage to two zones indicates core damage.

Each Target Set selects a zone as a core zone, which is a zone selected by at least one of the selected defense sets and one of the defense sets including the Level 1 core zone.

 Table 2 below shows the analysis results of the zone evaluation module 340 according to an embodiment of the present invention.

Here, 100-C01 represents the 100-foot ground level, containment building C, and compartment number 01, as well as the combination of the code of the defense module. In the same notation, 050-A01C represents 50 feet of ground level, auxiliary building A, compartment no. 01, compartment C.

For the APR1400 nuclear power plant, 112,468 combat attack sets were analyzed. The results of the analysis shown in Table 2 show that there are two zones in which the compartments are damaged due to a single zone of sabotage, and 955 zones where the compartments are damaged due to a combination of two zones, The area where the compartment was damaged and the radioactivity was released was analyzed to about 110,000.

3, a method of evaluating a core zone in a nuclear power plant and a method of reinforcing it to physically protect a core zone in a nuclear power plant are described.

Figure 3 illustrates a core zone assessment process in accordance with an embodiment of the present invention.

First, prepare nuclear facility information. As described above, this information is used to determine the inventory of radioactive materials by the facility information analysis department using the CDF number to determine whether sabotage reactor core is damaged. As an embodiment of the present invention, the core zone is determined only when the CDF value is 1.0E-04 / yr or more, that is, when the reactor core melts more than once every 10,000 years and exposure of the radiative substance occurs.

Once the radioactive exposure is identified, it is determined whether the corresponding scenario is a probabilistic safety assessment (PSA) logic model.

In this case, the order is different depending on whether or not the existing probabilistic safety assessment (PSA) logic model is present.

(PSA) logic model, the PSA model of the internal event is secured (step 1), and the PSA model and the database of external events such as fire, flood and hurricane . (Step 3) After that, the consolidated database will be converted to a sabotage fault tree.

However, if it is not a PSA logic model, it is a new internal event PSA model, so first (step 1) select the initial case of sabotage (step 2). Then, analyze the incident situation of sabotage (Step 3) Finally, based on this, Sabotage case tree is created by the above method.

This converted sabotage fault tree is composed of compartment breakage and classified into attack set and defense set. Then, by prioritization among the defense sets, the core zones are evaluated in the nuclear power plant.

The next step is to reinforce the physical protection of this critical area.

Unlike the conventional security response scenario evaluation system, the core zone evaluation system for deriving a response scenario in case of a core damage in the nuclear power plant of the present invention grasps a core zone that can cope with the core damage of a nuclear power plant in advance, We present a model. This has the advantage of being able to react quickly if the core is damaged by sabotage or the like.

In other words, probabilistic safety evaluation of nuclear power plant transforms fault trees into sabotage fault trees, and protects core areas by selecting only one most effective defense set through deriving all malicious actions and combinations that can cause radiation sabotage. This can drastically reduce the physical protection costs of nuclear power plants.

In addition, by analyzing and applying core areas, it is possible to identify and reinforce vulnerability of nuclear power plants in advance, to protect nuclear materials, to protect against illegal acts, to obstruct security against nuclear power plants and to destroy nuclear facilities. In addition to preventing sabotage, it has the effect of minimizing the impact of incidents and responding promptly.

The above-described embodiments are illustrative of the present invention, and the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (12)

A core zone evaluation system for deriving response scenarios for core damage in a nuclear power plant,
A radioactive information confirmation unit for checking whether or not the radioactive material is leaked;
A zone in which there is a system in which there is at least one system in which the radioactive material can be leaked by at least one of sabotage and natural disasters, A zone classifier for classifying a dangerous zone in which there is one or more systems that must be defended to allow the initial event to be resolved;
A main zone analyzer for analyzing at least one of the behavior of the sabotage in the main zone and the natural disaster through the fault tree;
/ RTI >
The main zone analyzing unit,
A processor including a logical model algorithm for a scenario in which the initial event alone or in combination with other malicious behavior may cause radiation sabotage;
Lt; / RTI >
The processor comprising:
Probabilistic safety assessment to analyze the damage of core in the event of a major accident. And
An external event determination model that determines the likelihood of a facility being destroyed by at least one of fire, flooding, and explosion;
/ RTI >
A core zone evaluation system for a nuclear power plant that analyzes key zones that are the areas where core damage is caused if the initial event occurs due to malicious activity in the hazard zone and the zone is damaged. delete delete The method according to claim 1,
In the internal event model of the probabilistic safety assessment,
A core zone evaluation system of a nuclear power plant including at least one of a reactor coolant loss accident, a loss of an off-site power supply at a power plant, a large-scale pipeline breakage at a secondary side, a loss of a water supply at a secondary side, The method of claim 1,
The main zone analyzing unit,
The area where the system of nuclear power plant core exists,
A target analysis module that classifies the hostile forces as an attack aggregation area that must be approached to generate sabotage; And
Defensive analysis module that classifies defensive areas that must be protected to prevent sabotage;
Wherein the core zone evaluation system of the nuclear power plant comprises: The method of claim 5,
The main zone analyzing unit,
The data of the target analysis module are used to classify the zone into a zone causing core damage by a sabotage for a single zone and a zone causing sabotage due to sabotage for a combination of two or more zones and selecting a core zone based on the classification result A zone evaluation module;
Further comprising: a core zone evaluation system for a nuclear power plant. In a method for assessing critical zones in a nuclear power plant by a critical zone assessment system,
Preparing nuclear facility information;
Calculating a core damage frequency based on the nuclear facility information, determining an inventory amount of the radioactive material using the calculated core damage frequency, and determining whether the radiation is exposed;
Determining whether the corresponding scenario is a probabilistic safety assessment (PSA) logic model if radiation is exposed;
Transforming the sabotage fault tree into a sabotage fault tree based on the determination;
Determining a set of attacks that must be approached in order to generate a radiation sabotage based on the sabotage failure tree and a set of defenses that must be protected to prevent radiation sabotage; And
Selecting a core zone with a priority among the defense sets;
A method of evaluating a core zone in a nuclear power plant, including a core zone evaluation system. 8. The method of claim 7,
In the case of the probabilistic safety assessment (PSA) logic model
Securing an internal event probabilistic safety assessment (PSA) logic model by the sabotage;
Generating a database by integrating the secured probabilistic safety assessment (PSA) logic model with an external event decision model by at least one of fire, flood, and hurricane; And
Transforming the sabotage fault tree into the sabotage fault tree through the generated database;
A method of evaluating a core zone in a nuclear power plant, including a core zone evaluation system. 8. The method of claim 7,
If it is not the probabilistic safety assessment (PSA) logic model,
Selecting a sabotage initial event;
Analyzing a sabotage incident of the selected initial event; And
Creating a fault tree of the sabotage case analyzing the accident occurrence;
A method of evaluating a core zone in a nuclear power plant, including a core zone evaluation system. delete delete delete

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