Performance Analysis for a 12-Finger CEA Drop Test of the SHN Unit 1

If a 12-Finger Control Element Assembly (CEA) is dropped into the core during power operation at 100%, the original Core Protection Calculator (CPC) will trip the reactor to protect safely the core with the Low Departure from Nucleate Boiling Ratio (DNBR) or High Local Power Density (LPD) trip functions. The Nuclear System Supply System (NSSS) Design Contract for Shin Han-ul Nuclear Power Plant 1 and 2 (SHN 1&2) is specified to apply a design improvement for the purpose of preventing the unnecessary reactor trip due to a 12-Finger CEA drop, slip and erroneous signals. The SHN 1 and 2 reflects the improved system design to prevent the reactor trip from a 12-Finger CEA drop. In order to verify the adequacy of design modifications, the single 12-Finger CEA drop test will be performed during the PAT of the SHN 1. The system performance analysis was performed by using the KISPAC, the ROCS and the CPC Fortran. In accordance with the results of the NSSS system and the RCOPS performance analysis, it is expected that the reactor trip signals will not be generated and the trip margins will be sufficient during the single 12-Finger CEA drop test in PAT of the SHN 1 unit.