Assessment of Realistic Departure from Nucleate Boiling Ratio (DNBR) Considering Uncertainty Quantification of Core Flow Asymmetry

Il Suk Lee, Dong Hyeog Yoon, Young Seok Bang, Tae Hoon Kim and Yong Chan Kim
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Il Suk Lee: Korea Institute of Nuclear Safety, 62 Gwahak-ro, Yuseong, Daejeon 34142, Korea
Dong Hyeog Yoon: Korea Institute of Nuclear Safety, 62 Gwahak-ro, Yuseong, Daejeon 34142, Korea
Young Seok Bang: Korea Institute of Nuclear Safety, 62 Gwahak-ro, Yuseong, Daejeon 34142, Korea
Tae Hoon Kim: Korea Institute of Nuclear Safety, 62 Gwahak-ro, Yuseong, Daejeon 34142, Korea
Yong Chan Kim: Department of Mechanical Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea

Energies, 2021, vol. 14, issue 5, 1-13

Abstract: Concern over the asymmetric phenomena in the core region has increased considering safety issues that are highly possible to reduce the thermal margin significantly in nuclear power plants. Since the seized reactor coolant pump (RCP) accident of an advanced power reactor 1400 (APR1400) can be regarded as a representative core asymmetric event with respect to core inlet flow, the departure from nucleate boiling ratio (DNBR), which is a regulatory acceptance criterion in nuclear safety, should be evaluated with consideration of the uncertainty range of the core inlet flow reflecting the actual geometry. This study investigates the DNBR quantitatively in the entire fuel assemblies in the core using several codes for system behavior, computational flow dynamics, sub-channel analysis, and uncertainty evaluation. Based on the results from a system thermal-hydraulic analysis of a seized RCP accident of APR1400, this study presents the uncertainty range calculated by computational fluid dynamics on the asymmetry of the core inlet flow. Damaged fuel rods are quantitatively identified through a sub-channel analysis, which presents statistic relevance to obtain the DNBR at 95% reliability and 95% accuracy level. Additionally, an optimized evaluation methodology of a non-loss of coolant accident (non-LOCA) is realized by several nuclear codes.

Keywords: departure from nucleate boiling ratio; asymmetry; core flow; nuclear safety; uncertainty (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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