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, Yong Chan Kim

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


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.

Original languageEnglish
Article number1504
Issue number5
Publication statusPublished - 2021 Mar 1

Bibliographical note

Funding Information:
Funding: The Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety (KOFONS) and the Nuclear Safety and Security Commission (NSSC), Republic of Korea grant number 1805004-0320-SB120.

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Asymmetry
  • Core flow
  • Departure from nucleate boiling ratio
  • Nuclear safety
  • Uncertainty

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Energy (miscellaneous)
  • Control and Optimization
  • Electrical and Electronic Engineering


Dive into the research topics of 'Assessment of realistic departure from nucleate boiling ratio (Dnbr) considering uncertainty quantification of core flow asymmetry'. Together they form a unique fingerprint.

Cite this