Analysis and evaluation of CPC/COLSS related test results during YGN 3 initial startup

YGN 3 is the first nuclear power plant to use the Core Protection Calculator (CPC) as the core protection system and the Core Operating Limit Supervisory System (COLSS) as the core monitoring system in Korea. The CPC is designed to provide on-line calculations of Departure form Nucleate Boiling Ratio (DNBR) and Local Power Density (LPD) and to initiate reactor trip if the core conditions exceed the DNBR or LPD design limit. The COLSS is designed to assist the operator in implementing the Limiting Conditions for Operation (LCOs) in Technical Specifications for DNBR/Linear Heat Rate (LHR) margin, azimuthal tilt, and axial shape index and to provide alarm when the LCOs are reached. During YGN 3 initial startup testing, extensive CPC/COLSS related tests were performed to verify the CPC/COLSS performance and to obtain optimum CPC/COLSS calibration constants at various core conditions. Most of test results met their specific acceptance criteria. In the case of missing the acceptance criteria, the test results were analyzed, evaluated, and justified. Through the analysis and evaluation of each of the CPC/COLSS related test results, it can be concluded that the CPC/COLSS are successfully implemented as designed at YGN 3. 6 figs., 5 tabs., 11 refs. (Author)