Tenth Cofrentes reload licensing analysis with RETRAN-03 methodology

The reload transient analysis methodology developed for the Cofrentes boili ng wafer reactor-6, 2894-MW(thermal)-rated nuclear power plant is based on the RETRAN-03/MOD1 code. Cross-section files have been calculated with the CASMO-3/SIMULATE-3/SLICK codes. The system and hot-channel thermal-hydrauli c responses have been predicted with the RETRAN-03 code, and the thermal ma rgin for each fuel type has been determined by the TCPUIT code. Transient analyses are performed under several initial conditions to improv e the plant operational flexibility. The two most thermal limiting plant tr ansients were simulated: (a) generator load rejection with concurrent failu re of the condenser bypass system and (b)failure of the feedwater flow cont rol system to maximum demand. In addition, overpressure is evaluated with R ETRAN-03, i.e., a closure of the main-isolation-valve transient. The Cofrentes tenth reload licensing analyses are verified against official fuel vendor calculations. The results obtained agree with them and cover t he vendor thermal margins for the different fuel types considered.