The Establishment and Simulation of TRACE/FRAPTRAN/MELCOR/SNAP Model for Chinshan Nuclear Power Plant Ultimate Response Guideline

Abstract

Chinshan Nuclear Power Plant (NPP) was built in 1970 and is a BWR/4 NPP. The original rated power of Chinshan NPP for each unit is 1775 MW. Chinshan NPP finished the project of SPU (stretch power uprate) and the operating power is 1840 MW now. In order to ensure the NPPs safety, the simulation and analysis of the transients for the NPPs are very important work. After the Fukushima NPP disaster occurred, there is more concern for Taiwan NPPs safety. For the simulation of ultimate response guideline (URG), the TRACE/SNAP model of Chinshan NPP was established in this research. The reactor depressurization, low pressure water injection, and containment venting are the main actions of URG. This research focuses to assess the URG utility of Chinshan NPP under Fukushima-like conditions. This study consists of four steps. The first step is the establishment of Chinshan NPP TRACE/SNAP model. In order to evaluate the TRACE/SNAP model’s system response, startup tests and FSAR data were used to compare with the results of TRACE. The second step is the URG simulation and analysis under Fukushima-like conditions by using Chinshan NPP TRACE/SNAP model. In this step, the no URG case was also performed in order to confirm the URG effectiveness of Chinshan NPP. Additionally, the MELCOR/SNAP model of Chinshan BWR/4 NPP was also established for the above cases. The prediction comparison of TRACE and MELCOR was done. Third, the sensitivity study of URG and the required raw water injection were performed. According to TRACE results, the URG can keep the peak cladding temperature (PCT) below the criteria 1088.7 K under Fukushima-like conditions. It indicates that Chinshan NPP can be controlled in a safe situation. If Chinshan NPP does not perform the URG under Fukushima-like conditions, the water level may drop lower than TAF (top of active fuel) which means a safety issue about the fuel rods may be generated. Finally, by using FRAPTRAN code and the results of TRACE, the analysis was performed in order to evaluate the mechanical property and integrity of fuel rods.