One-dimensional ex-vessel coolability analysis of debris beds formed in OPR1000 pre-flooded reactor cavity

• Published in: Annals of nuclear energy 2020-04, Vol.138, p.107123, Article 107123
• Main Authors: Na, Hanbee, Kang, Dong Gu, Ryu, Yong-Ho, Lee, Hee Joon
• Format: Article
• Language: English
• Subjects: Concrete ablation; Debris bed coolability; Melt coolability and concrete interaction (MCCI); Pre-flooding cavity
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2019.107123

•The feasibility of cooling molten corium of OPR1000 nuclear power plants is studied.•The transition of water penetration depth in the debris bed is calculated.•The amount of concrete ablation due to heat transfer to the structure is calculated.•It is proved fragmented particles are well spread for pre-flooded cavity strategy. This paper presents a feasibility study on a pre-flooded cavity strategy for cooling molten corium in OPR1000 nuclear power plants. The characteristics of debris beds formed in the pre-flooded reactor cavity are assumed to be the same as COOLOCE-8 BED, STXY BED, and POMECO BED-5. We conducted one-dimensional safety analysis on the coolability of the debris beds and the integrity of the containment during ex-vessel cooling. If the debris bed is uniformly formed throughout the reactor cavity, the integrity of the containment can be maintained. However, if the debris bed is formed only beneath the reactor vessel narrowly, the integrity of the containment structure cannot be maintained. Therefore, in order to assess the adequacy of the pre-flooded cavity strategy for ex-vessel cooling in OPR1000, the spreadability of fragmented particles and the possible debris bed shapes are needed to be studied thoroughly.