Best Estimate Plus Uncertainty Analysis of a Pressurizer Surge Line Break LOCA on China’s Advanced PWR

The Pressurizer Surge Line Break (PSLB) Loss of Coolant Accident (LOCA) is one of the representative design basis accidents (DBAs) which leads to the discharge of the primary coolant into the containment atmosphere. In this paper, the RELAP5 best-estimate code was used to perform a PSLB LOCA on China’s Advanced Pressurized Water Reactor (PWR). According to the phenomenon identification and ranking table (PIRT), the parameters that contribute significantly to the reactor safety standard were determined. Then, simple random sampling was performed using DAKOTA software and a set of 59 calculations were performed based on the Wilks’ formula. The uncertainty bands of key output parameters were obtained with 95/95 criterion, and the upper band of maximum containment pressure did not exceed the safety limit. Lastly, important uncertainty contributors for the maximum containment pressure were identified through sensitivity analysis.