Methodology And Practice Of Licensing LOCA Analysis Based On Regulation Codes And RELAP5 Platform

Licensing LOCA analysis is an important issue of Nuclear Power Plant (NPP) design and safety analysis. According to the regulations, both conservative and best estimate methodology can be used for licensing LOCA evaluation. Follow the current situation, the author endeavors to develop conservative evaluation methodology and tool based on advanced thermal-hydraulic RELAP5 system analysis platform, applying certain models and approaches recommended by related regulation code, which is not only anticipated to guarantee safety but also expected to somewhat improve economy.RELAP5 is a large-scale advanced thermal-hydraulic system analysis program. However, some models and correlations applied do not conform to code-required evaluation model which, therefore, lead to RELAP5 itself not applicable for licensing LOCA analysis directly, except that modifications and verifications meeting the code requirements are made. Since blowdown and boiling heat transfer process is crucial in LOCA, two-phase choking and boiling heat transfer models in RELAP5 platform are selected to be modified and verified for evaluation, in accordance with the relevant regulations.