Assesment of safety analysis code on integral effect test with SNUF

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.

A Safety and Performance Analysis CodE (SPACE) is a thermal-hydraulics computer code under development of South Korea for analysis of complicated phenomena in the nuclear power plants including anticipated transients and postulated accidents. This study assessed the SPACE code capability for prediction of the direct vessel injection (DVI) system, which is adopted as a key safety system in the APR1400 reactor. This study mainly focused on the DVI line break accident, one of the postulated SBLOCA accidents that might result in loss of main coolant water and a quarter of safety injection water simultaneously, for assessment of the code. In order to evaluate the code prediction capability on the phenomena associated with the downcomer seal clearing at the DVI line break, this study selected the SNUF DVI break experiment as the experimental benchmark. This experiment is a reduced-height and reduced-pressure (RHRP) integral test facility designed for simulation of the primary loop of APR1400 designed in Korea. As a result, the SPACE showed reliable agreement with the experimental data on seal clearing phenomena well predicting both the start point of downcomer seal clearance and loop seal clearance. In the DVI system, downcomer seal clearing appears to be more important than loop seal clearing because the vapor generated from core flows through downcomer to broken DVI line. Therefore, the core collapsed level increases as the vapor pressure decreases in the core