Preliminary criticality analysis of a partially damaged reactor core under different scenarios

• A partially damaged reactor model was proposed. • Model consists of fuel debris at the core center and intact fuel at the core edges. • Impact of the fuel debris shape was investigated. • Impact of the V m /V f ratio was investigated. This study examined the criticality characteristics of a partially damaged reactor model, in which fuels located at the core center melt into fuel debris of varying shapes, while fuels situated at the core edge remain intact. The investigation was conducted using the Serpent code with the JENDL-5 library. The results indicate that when the volume of fuel debris is constant, the shape of the fuel debris does not cause significant alterations in the variation of the k eff of the system. In contrast, for the scenario of the variable fuel-debris volume, the k eff variation law can be divided into two groups for the reference case with a system temperature of 300 K and no boron in the water. The first group comprises fuel debris with cuboid and cylindrical shapes, while the second group includes spherical, conical, and truncated conical shapes.