Seismic Fragility Analysis of Equipment in Nuclear Facilities Using the Random Vibration Theory

Jin Ho Lee

doi:10.7734/COSEIK.2025.38.4.269

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2025 Vol.38, Issue 4 Preview Page Next Page

Research Paper

Seismic Fragility Analysis of Equipment in Nuclear Facilities Using the Random Vibration Theory 무작위진동이론에 기반한 원전 기기의 지진취약도분석

31 August 2025. pp. 269-277

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Abstract

In this study, a seismic fragility analysis methodology for equipment installed in nuclear power plants is proposed using the random-vibration-theory (RVT) approach. The proposed method can be efficiently applied to diverse dynamic analyses such as site response analysis and soil–structure interaction analysis of in nuclear power plant environments. The RVT technique does not require the direct use of ground motion time histories, making it particularly beneficial in regions such as Korea that lack extensive records of significant seismic events. The power spectral density (PSD) function of the input ground motion is employed to perform a stochastic earthquake response analysis of the soil–structure interaction system, and the PSD function of the resultant pseudo-acceleration of equipment installed within the structure is subsequently derived. The cumulative distribution function of the in-structure response spectrum (ISRS) is then obtained by applying peak factors to the PSD function to estimate the peak value of the pseudo-acceleration of the equipment, and the failure probability and fragility curve of the equipment are estimated based on its failure criteria. The seismic fragility analysis method, developed using the proposed RVT methodology, is applied to equipment installed in a nuclear power plant facility situated on a homogeneous hard or soft rock half-space, and the validity of the proposed analysis method is demonstrated by comparing the results with those obtained from the response-history methodology.

Keywords

seismic fragility analysis

stochastic dynamic analysis

power spectral density function

random vibration theory

peak factor

in-structure response spectrum

이 연구에서는 원전 시설물의 부지응답해석 및 지반-구조물 상호작용 해석 등 다양한 동적 문제에 효율적으로 활용할 수 있는 무작위진동이론(random vibration thoery, RVT) 방법론을 사용하여 원전 구조물에 설치된 기기의 지진취약도 분석기법을 제안한다. RVT에 기반한 해석기법은 입력지반운동의 시간이력을 직접적으로 필요로 하지 않기 때문에 우리나라와 같이 강진지진기록이 충분하지 않은 지역에서 유용한 방법이다. 입력지반운동의 파워스펙트럼밀도(power spectrum density, PSD) 함수를 사용하여 대상 지반-구조물 상호작용계의 추계학적 지진응답해석을 수행하고, 구조물 내부에 설치된 기기의 유사가속도에 대한 PSD 함수를 산정한다. 이 PSD 함수에 무작위진동 첨두응답의 확률분포를 추정할 수 있는 첨두값 계수를 적용하여 기기 유사가속도의 첨두값, 즉 구조응답스펙트럼의 누적분포함수를 추정하고, 기기의 고장 조건을 적용하여 기기 고장 확률과 취약도곡선을 산정한다. 제안한 RVT 방법론에 근거한 지진취약도 분석기법을 균질 반무한 경암 및 연암 지반에 놓인 원전 구조물에 설치된 기기에 적용하고, 응답이력 방법론에 의한 결과와 비교하여 제안한 기법의 정확성을 검증한다.

키워드

지진취약도분석

추계학적 동해석

파워스펙트럼밀도 함수

무작위진동이론

첨두값 계수

구조응답스펙트럼

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Information

Publisher :Computational Structural Engineering Institute of Korea
Publisher(Ko) :한국전산구조공학회
Journal Title :Journal of the Computational Structural Engineering Institute of Korea
Journal Title(Ko) :한국전산구조공학회 논문집
Volume : 38
No :4
Pages :269-277
Received Date : 2025-04-28
Revised Date : 2025-05-20
Accepted Date : 2025-05-20
DOI :https://doi.org/10.7734/COSEIK.2025.38.4.269

Journal of the Computational Structural Engineering Institute of Korea ISSN:1229-3059(Print) 2287-2302(Online) 한국전산구조공학회 논문집

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