Abstract
The study presents the approach of CPR transient uncertainty for KSNPS, which is similar to CSAU methodology. This procedure can be reduced to three parts: Constructing the procedure of code analysis, transient simulation and phenomena identification, and quantify- ing the uncertainty. The codes used in the study includes the BWRHB, SIMULATE-3, SLICK, RETRAN, in which the applicability and capability of the codes have been confirmed by the researching institute and also licensed by the ROC AEC’s liscense. These codes are essential to core management, core reload, and safety analysis. To perform the critical power ratio (CPR), we start at the thermal-hydraulic parameters calculation to establish the nominal model initial values, and then get the neutron kinetic files at specific burn-up point by using SIMULATE-3 to simulate the neutron behavior in core. Finally, we run the transient case by using Retran code to simulate the transient. According to the transient results, we can perform phenomena identification and determine the PIRT. In the uncertainty analysis, two statistic methods have been used. The first one is based on the population parameters. By varying the individual parameter in the PIRT, we can quantify all uncertainties to get the population CPR at 95% confidence level. The second method is based on the non-parameters statistics, which uses Montecarlo method to vary all parameters in the PIRT simultaneously. After performing certain calculations, the maximum critical power ratio can be obtained by ranking the calculation results. Finally, we compare the two results which are based on different statistcs.