• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.187-194
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• 2016

A single fire event within a fire area can cause multiple initiating events considered in internal events probabilistic safety assessment (PSA). For an example, a fire event in turbine building fire area can cause a loss of the main feed-water and loss of off-site power initiating events. This fire initiating event could result in special plant responses beyond the scope of the internal events PSA model. One approach to address a fire initiating event is to develop a specific fire event tree. However, the development of a specific fire event tree is difficult since the number of fire event trees may be several hundreds or more. Thus, internal fire events PSA model has been generally constructed by modifications of the pre-developed internal events PSA model. New accident sequence logics not covered in the internal events PSA model are separately developed to incorporate them into the fire PSA model. Recently, many fire PSA models have fire induced initiating event fault trees not shown in an internal event PSA model. Up to now, there has been no analytical comparative study on the constructions of fire events PSA model using internal events PSA model with and without fault trees of initiating events. In this study, the changing process of internal events PSA model to fire events PSA model is analytically presented and discussed.

• Fire Science and Engineering
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• v.17 no.1
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• pp.40-45
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• 2003

In this paper many vulnerable areas of the present fire PSA methodology were revealed to apply risk-informed fire protection to nuclear power plants. The results and insights from the fro PSA should be used as a part of a risk-informed decision making process rather than the complete technical basis for decision making. The degree of support and scope of applications is dependent on the accuracy and validity of the model used in the fire PSA. Accordingly; the usefulness of the fire PSA will increase as ongoing research and development efforts lead to improvements in the state of the art technology and as improvements in the implementation of the state of the art technology lead to more consistent results.

• Nuclear Engineering and Technology
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• v.43 no.3
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• pp.271-278
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• 2011

When performing fire PSA in a nuclear power plant, an event mapping method, using an internal event PSA model, is widely used to reduce the resources used by fire PSA model development. Feasible initiating events and component failure events due to fire are identified to transform the fault tree (FT) for an internal event PSA into one for a fire PSA using the event mapping method. A surrogate event or damage term method is used to condition the FT of the internal PSA. The surrogate event or the damage term plays the role of flagging whether the system/component in a fire compartment is damaged or not, depending on the fire being initiated from a specified compartment. These methods usually require explicit states of all compartments to be modeled in a fire area. Fire event scenarios, when using explicit identification, such as surrogate or damage terms, have two problems: (1) there is no consideration of multiple fire propagation beyond a single propagation to an adjacent compartment, and (2) there is no consideration of simultaneous fire propagations in which an initiating fire event is propagated to multiple paths simultaneously. The present paper suggests a fire propagation equation to identify all possible fire event scenarios for an explicitly treated fire event scenario in the fire PSA. Also, a method for separating fire events was developed to make all fire events a set of mutually exclusive events, which can facilitate arithmetic summation in fire risk quantification. A simple example is given to confirm the applicability of the present method for a $2{\times}3$ rectangular fire area. Also, a feasible asymptotic approach is discussed to reduce the computational burden for fire risk quantification.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2263-2275
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• 2023

In general, an internal fire events probabilistic safety assessment (PSA) model is quantified by modifying the pre-existing internal event PSA model. Because many pieces of equipment or cables can be damaged by a fire, a single fire event can lead to multiple internal events PSA initiating events (IEs). Consequently, when the fire events PSA model is quantified, inappropriate minimal cut sets (MCSs), such as duplicate MCSs, may be generated. This paper shows that single quantification of a hypothetical single-top fire event PSA model may generate the following four types of inappropriate MCSs: duplicate MCSs, MCSs subsumed by other MCSs, nonsense MCSs, and MCSs with over-counted fire frequencies. Among the inappropriate MCSs, the nonsense MCSs should be addressed first because they can interfere with the right interpretation of the other MCSs and prevent the resolution of the issues related to the other inappropriate MCSs. In addition, we propose a resolution process for each of the issues caused by these inappropriate MCSs and suggest an overall procedure for resolving them. The results of this study will contribute to the understanding and resolution of the inappropriate MCSs that may appear in the quantification of fire events PSA models.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.253-257
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• 2011

본 논문에서는 설계중인 스마트원전에 대한 화재 PSA 방법과 결과 그리고 민감도분석 결과를 기술하였다. 기존 국내 원전 화재 PSA에서는 EPRI의 fire PRA implementation guide에 따라 수행해왔었다. RG 1.189에 따르면 NFPA 805를 채택하는 원전이나 신규원전은 NUREG/CR-6850 방법에 따라 화재 PSA를 수행해야만 한다. 스마트는 설계단계의 원전이기에 화재 PSA 수행위한 충분한 설계정보가 없고 스마트의 선행호기도 없다. 따라서 NUREG/CR-6850 방법을 스마트에 모두 적용할 수 없어 EPRI fire PRA implementation guid와 NUREG/CR-6850 방법을 사용하여 스마트 원전에 대한 화재 PSA를 수행하였다. 화재 PSA 결과에 중요한 영향을 미치는 요인들에 대해 민감도분석을 수행하였다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.151-154
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• 2012

기존 국내원전의 화재 PSA는 EPRI가 개발한 방법론을 이용하여 화재 PSA를 수행하여 오고 있다. 미국 NRC는 EPRI와의 공동연구를 통하여 새로운 화재 PSA 방법론(NUREG/CR-6850)을 개발하였고, NFPA-805 코드를 적용하는 미국 원자력발전소들에 대해서 이 방법론을 적용한 PSA를 수행하는 것을 권고하고 있다. 본 논문에서는 국내원전에 신규 PSA 방법론 적용시 논의되어야 할 사항들 중 지진화재 연계성(또는 지진-화재 상호작용)평가 방법론에 대한 제안 및 고려사항을 기존 해외 사례를 참고하여 기술하였다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.31-32
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• 2013

NUREG/CR-6850에 따른 신규 화재 PSA 방법론으로 간단한 계통으로 이루어진 가상의 원전을 대상으로 교육용 신 화재 PSA 방법 기본모델을 개발하였다. 기본 모델을 CCDP 방법과 IPRO-ZONE을 이용한 화재 고장수목(FT) 자동 생성 방법으로 개발하였으며, FT 자동 생성으로 많은 시간과 노력을 절약할 수 있었다. 개발된 신 화재 PSA 방법 기본모델을 이용한 교육을 통해, 향후 복잡한 신 화재 PSA 방법이 국내 산업계에 쉽게 확산될 것이다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.231-234
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• 2011

기존 국내원전의 화재 PSA는 기존 EPRI가 개발한 방법론을 이용하여 화재 PSA를 수행하여 오고 있다. 미국 NRC는 EPRI와의 공동연구를 통하여 새로운 PSA 방법론(NUREG/CR-6850)을 개발하였고, NFPA-805 코드를 적용하는 미국 원자력발전소들에 대해서 이 방법론을 적용한 PSA를 수행하는 것을 권고하고 있다. 본 논문에서는 국내 원전의 참조 주제어실을 대상으로 신규 방법론을 적용하여 노심손상빈도 영향을 평가하였고, 국내원전에 신규 방법론 적용시 논의되어야 할 사항들을 포함하였다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.109-112
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• 2012

원자력발전소는 타 산업시설에 비해 화재발생 가능성이 낮으나 방사성물질 누출가능성을 최소화하기 위하여 심층방어와 다중방호 설계를 통한 안전성확보가 매우 중요하다. 이를 위해 국내에서는 화재위험도분석(FHA)과 안전정지능력분석(SSA) 및 화재 확률론적안전성분석(Fire PSA)을 수행하고 있으며, 이 중 화재 PSA는 주요 화재구역 선별, 구역별 화재발생빈도 및 기기손상확률 계산, 화재사고 경위분석 및 화재취약성 파악 등을 분석한다. 본 논문에서는 미국 원자력규제위원회(USNRC)와 전력연구소(EPRI)가 공동 연구개발한 화재 PSA 방법론인 NUREG/CR-6850 기법을 적용하여, 화재 PSA에 필요한 화재점화빈도(Fire Ignition Frequency)를 정량적으로 계산하였다. 정확한 결과값을 도출하기 위해 매크로를 이용한 프로그램인 FIFA(Fire Ignition Frequency Analyzer)를 개발하였으며, 향후 국내 원전 화재 PSA 분석업무에 유용하게 사용될 수 있을 것으로 기대된다.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.96-99
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• 2015

Norwegian Continental Shelf(NCS) is known as rich oil & gas reservoir and takes one third(1/3) of total continental shelf of Europe.(As of year 2013, Norway ranked third in the world in terms of exporting natural gas.) Until recent low oil price stream, development of oil & gas in NCS was active and perceived as profitable business. This paper describes study of living quarter fire protection for PSA AoC to prepare for likely increasing demands of offshore projects in NCS field.