International Journal

Assessment of realistic departure from nucleate boiling ratio (Dnbr) considering uncertainty quantification of core flow asymmetry
Year of publication 2021
Title of paper Assessment of realistic departure from nucleate boiling ratio (Dnbr) considering uncertainty quantification of core flow asymmetry
Author Il Suk Lee, Dong Hyeong Yoon, Young Seok Bang, Tae Hoon Kim, Yong Chan Kim
Publication in journal Energies
Publication date 1 March 2021
Volume & other data Volume 14, 1504
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 Asymmetry, Core flow, Departure from nucleate boiling ratio, Nuclear safety, Uncertainty
issn Number 19961073
Status of publication
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