Evaluation of LBLOCA mass/energy release and containment pressure using best-estimate computer code system for Korean standard nuclear plant

Mass/energy release and containment pressure was calculated using the best-estimate computer code system for KSNP large break loss-of-coolant accident, the design bases accident for the containment environmental equipment qualification. In addition, and evaluation was performed by comparing with the results of the present licensing analysis methodology. It reveals that substantial design margin exists in the licensing analysis methodology due to the conservative initial condition/design data and conservative assumption/model application associated with the major thermal hydraulic phenomena such as critical flow and heat transfer across the steam generator. Further study is needed such as the evaluation of the effect of break size and location, the review of the models in the best-estimate codes, and the evaluation of licensibility of the best-estimate analysis methodology. It is expected that improved economic benefit can be obtained through the relaxation of containment environmental equipment qualification curve if the systematic development of best-estimate computer code system is steadily performed