A trip coverage analysis of total loss of class IV power for Wolsong 1 with CANFLEX-NU fuel

This analysis is intended to show that there is adequate reactor trip coverage (i.e., two parameters for each shutdown system) to prevent fuel and fuel channel failure and excessive Primary Heat Transport (PHT) system overpressure for a total loss of class IV power event for Wolsong 1 with CANFLEX-NU fuel. The analysis was performed using the CATHENA circuit model and slave channel model for channel O6. The effect of the reactor regulating system operational or frozen was assessed to show that adequate trip coverage is available for equilibrium CANFLEX-NU fuel and fouled steam generators. For a total loss of class IV power to all PHT pumps at all different initial power levels, there are at least two effective trip parameters for both SDS1 and SDS2. The peak reactor outlet header pressure was within the limit for ASME level B (SDS1) and C (SDS2) transients and fuel failure was precluded for all cases. At 2% initial power and lower, a trip is not required, when the reactor regulating system is operational. Therefore, adequate trip coverage is demonstrated for all cases