Bethsy Test 6.9C Mid-Loop Operation Phenomena Identification Using RELAP5 NPA

Test 6.9c OECD ISP-38 was performed on “BETHSY” facility, France on April 14. 1992 and simulated loss of RHR system during Mid-Loop operation at 0.5% of nominal value core power. Initial liquid level in RCS was at horizontal axis of the hot legs. Pressurizer and steam generator manways were opened 1 s after the transient was initiated. The paper presents the test observation to the physical phenomena comparing to the experimental data using RELAP5 NPA (Nuclear Plant Analyzer) graphical postprocessor. The most important and interesting turned out to be coolant distribution around the loops.