A study on the NSSS thermal-hydraulic modeling for Kori no.1 nuclear power plant

The nuclear steam supply system thermal-hydraulic module (named 'ARTS' code) is adopted to simulate the nuclear plant simulator for KORI unit 1. The best-estimate code RETRAN developed by EPRI is selected as a reference code for the ARTS and is the possibility of training personnel to act in terms of not only the design-basis but rather beyond the design-basis accidents. To develop the RETRAN code as a nuclear steam supply system thermal-hydraulic module for the simulator, a number of code modifications, such as simplifications and removing of discontinuities of the physical correlations, were made to satisfy the simulator requirements of robustness and real time calculation capability. Some simplified models and a backup system were also developed to simulate some transients that cannot be efficiently calculated by the RETRAN. And its scope for the simulation has been extended by supplementation of new calculation modules such as a dedicated pressurizer relief tank model and a backup model. The supplement is developed so that users cannot recognize the model change from the main ARTS module. For the transient behavior, the ARTS module is well adapted for the Kori unit 1 NPP simulator. The simulated results show good agreement with the plant data and the ANSI/ANS-3.5-1998 simulator software performance criteria under steady state or transient conditions