Integrated risk assessment for multi-unit NPP sites—A comparison

Kumar, Chandan; Hassija, Varun; Velusamy, K.; Balasubramaniyan, V.

doi:10.1016/j.nucengdes.2015.06.025

Cited by 19 publications

(3 citation statements)

References 7 publications

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“…Energies 2021, 14, x FOR PEER REVIEW probabilities, and then these OR combination probabilities are converted into CCFs in Equation (6). On the other hand, SVN integration is employed for the fu lation calculation of Model B.…”

Section: Calculation Results For Succdp and Sucdfmentioning

confidence: 99%

“…In Model A, all correlated seismic failures of intra-unit and inter-unit redundant/identical components are converted into seismic failures. In Model B, all correlated seismic failures of intra-unit redundant/identical components are replaced with one typi- In order to avoid singular Σ ρ for the full correlation calculation of Model A, MVN integration with ρ ij = 0.999 instead of 1.0 is used for calculating the OR combination probabilities, and then these OR combination probabilities are converted into seismic CCFs in Equation (6). On the other hand, SVN integration is employed for the full correlation calculation of Model B.…”

Section: Calculation Results For Muccdp and Mucdfmentioning

confidence: 99%

“…The initial multi-unit risk study [2] was performed due to the gradually increasing concern regarding multi-unit nuclear accidents. After the Fukushima Daiichi NPP accident in 2011 [3], many studies for multi-unit probabilistic safety assessments (MUPSAs) have been conducted [4][5][6][7][8][9][10][11][12][13].…”

Section: Introduction 1backgroundmentioning

confidence: 99%

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Sensitivity Study on the Correlation Level of Seismic Failures in Seismic Probabilistic Safety Assessments

2021

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It is popular that correlated seismic failures spread over the fault tree of a seismic probabilistic safety assessment (PSA) for a nuclear power plant (NPP). To avoid the calculational difficulty of core damage frequency (CDF), the fault tree has been simplified by replacing correlated seismic failures with one typical seismic failure by assuming a full correlation among the correlated seismic failures. Then, the approximate seismic CDF of a seismic single-unit PSA (SUPSA) has been calculated for decades with this simplified SUPSA fault tree. Furthermore, current seismic multi-unit PSAs (MUPSAs) have been performed with imperfect seismic MUPSA models that were generated by combining such imperfect seismic SUPSA fault trees. The authors of this study recently developed a method that can calculate an accurate seismic CDF by converting correlated seismic failures into seismic common cause failures (CCFs). In this study, accurate and imperfect MUPSA models were created and their seismic CDFs were compared. The results of this study show that the seismic CDFs in SUPSA and MUPSA are drastically distorted and safety margins are accordingly distorted when the full correlation assumption is employed. Thus, this study shows that very careful attention should be paid to calculating and interpreting seismic CDFs for the single-unit and multi-unit NPP regulations.

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Section: Calculation Results For Succdp and Sucdfmentioning

confidence: 99%

Section: Calculation Results For Muccdp and Mucdfmentioning

confidence: 99%