Journal of the Korean Society of Safety (한국안전학회지)

The Korean Society of Safety (한국안전학회)
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A Simple Approach to Calculate CDF with Non-rare Events in Seismic PSA Model of Korean Nuclear Power Plants

국내 원자력발전소 지진 PSA의 CDF 과평가 방지를 위한 비희귀사건 모델링 방법 연구

  • Lim, Hak Kyu (Department of NPP Engineering, KEPCO International Nuclear Graduate School)
  • 임학규 (한국전력국제원자력대학원대학교 원자력산업학과)
  • Received : 2021.09.14
  • Accepted : 2021.10.07
  • Published : 2021.10.31
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Abstract

Calculating the scrutable core damage frequency (CDF) of nuclear power plants is an important component of the seismic probabilistic safety assessment (SPSA). In this work, a simple approach is developed to calculate CDF from minimal cut sets (MCSs) with non-rare events. When conventional calculation methods based on rare event approximations are employed, the CDF of industry SPSA models is significantly overestimated by non-rare events in the MCSs. Recently, quantification algorithms using binary decision diagrams (BDDs) have been introduced to prevent CDF overestimation in the SPSA. However, BDD structures are generated from a small part of whole MCSs due to limited computational memory, and they cannot be reviewed due to their complicated logic structure. This study suggests a simple approach for scrutinizing the CDF calculation based on whole MCSs in the SPSA system analysis model. The proposed approach compares the new results to outputs from existing algorithms, which helps in avoiding CDF overestimation.

Keywords

Acknowledgement

This work was supported by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety (KoFONS) using the financial resource granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea. (No 1705001)

References

  1. M. K. Ravindra and C. R. Sundararajan, "Seismic Risk Assessment, Probabilistic Structural Mechanics Handbook-Theory and Industrial Applications", Chapter 19, Springer Science+Business Media Dordrecht, 1995.
  2. Kennedy, R.P., Cornell, C.A., Campbell, R.D., Kaplan, S., Perla, H.F., "Probabilistic Seismic Safety Study of an Existing Nuclear Power Plant", Nucl. Eng. & Des., 59(2), pp.315-338, 1980 . https://doi.org/10.1016/0029-5493(80)90203-4
  3. S. K. Park and W. S. Jung, "A New Quantification Method for Multi-Unit Probabilistic Safety Assessment", J. Korean Soc. Saf., Vol. 35, No. 1, pp. 97-106, 2020. https://doi.org/10.14346/JKOSOS.2020.35.1.97
  4. Electric Power Research Institute, "Seismic Probabilistic Risk Assessment Implementation Guide", EPRI 1002989, 2003.
  5. American Society of Mechanical Engineers/American Nuclear Society (ASME/ANS), "Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications", ASME/ANS-RA-Sa-2009, Addenda to ASME/ANS RA-S-2008, 2009.
  6. Korea Atomic Energy Research Institute, "AIMS-PSA Release 2 Reference Manual", KAERI-ISA-MEMO-AIMS-03-KOR, 2012.
  7. Electric Power Research Institute, "FTREX 1.9 Software Manual", EPRI 3002012968, 2018.
  8. H. K. Lim, "A Study of System Analysis Method for Seismic PSA of Nuclear Power Plants", J. Korean Soc. Saf., Vol. 34, No. 5, pp. 159-166, 2019.
  9. W. S. Jung, "BeEAST Version 1.1 User Manual", Sejong University, 2017.
  10. Nuclear Safety and Security Committee, "A Study on System Modeling of Seismic PSA to Prevent Overestimation of Seismic CDF", NSTAR-19NS42-91, 2019.
  11. P. Zvonceka and O. Nusbaumera, "Comparison of MCUB and MCS BDD Fault Tree Solution Algorithms using Leibstadt Nuclear Power Plant Model", Probabilistic Safety Assessment and Management PSAM 14, Los Angeles, CA, USA, 2018.