In pressurized water reactor (PWR), nuclear fuel rod comprises a pile of fuel pellet surrounded by a cladding. Sintered extensively uranium oxide and mixed oxide pellets are used as a nuclear reactor fuel. More advanced fuels are recently required for the more severe operating condition such as higher burn-up and increased fuel cycle.
Among the advanced fuel pellet, Missing Pellet Surface (MPS) reduction pellet is considered recently. MPS predominantly extended to the pellet end. The fragment of fuel materials produced by such chipping may become trapped in the gap between the peripheral wall of the pellets and the cladding and increase the mechanical stress on the cladding, which can lead to local cladding failure due to pellet clad mechanical interaction (PCMI). To solve this problem, research is conducted on the modification of the fuel pellet shape such as dish and chamfer.
In this study, the changed dish and chamfer of the nuclear fuel pellet are first simulated using Finite Element Method (FEM). From the simulated samples, the mechanical testing is performed to find the lowest percent defective of fuel pellets. Especially, the loadability test is performed to evaluate the chipping reduction performance of stacked fuel pellet behavior in the fuel rod.