BWR fuel rod behavior evaluation for preconditioning power ramps with FEMAXI-V

The licensing authorities around the world usually set a limit value to the operation LHGR, as a function of burnup. Such limit provides a bound state to a steady state operation, but also prevents against some thermal and mechanical phenomena that could occur during overpowered transients. In particular, in some countries, the PCI limit is set based on experimental ramp tests and directly related to the LHGR limit value. Thus, to avoid violating the PCI limit, fuel conditioning procedures are still required for both barrier and non-barrier fuel. Simulation of the power ramp procedures to be performed by the reactor operator during startup or power increase maneuvers is advisable as a preventive measure of possible overpower consequences on the fuel thermomechanical behavior.The thermomechanical behavior of BWR fuel rod is analyzed for fuel preconditioning procedures. Five different preconditioning computations were performed with the FEMAXI-V code, each with three different ascending linear power rate ramps. The starting point of the ramps was taken from data of the Unit 1 from the Laguna Verde Nuclear Power Plant, located in MEXICO. The top limit of the ramps was the threshold linear power at which failure by PCI could occur, as a function of burnup.

► We make use FEMAXI-V code to evaluate BWR fuel rods performance. ► Different power ramps were applied to observe fuel rod behavior under preconditioning. ► Several parameters are observed when pellet–cladding interaction occurs.