The multi-fluid multi-phase subchannel analysis code KAMUI for subassemblyaccident analysis of an LMFR

A computer program KAMUI has been developed to simulate multi-dimensional t hermal-hydraulic behaviors of the coolant and disrupted fuels in a subassem bly under hypothetical accident conditions of a Liquid-Metal Fast Reactor ( LMFR) where the strong momentum and thermal coupling of the coolant flow do minates the material relocation. The KAMUI code is based on the subchannel analysis approach to model the fuel pin array geometry and has a two-veloci ty held, multi-phase/multi-component formulation for transport phenomena wi th relatively simple but conventional constitutive models. The code has bee n applied to and validated for a total inlet blockage simulation experiment SCARABEE BE+1. The results show the significance of the radial heat loss t hrough the wrapper tube wall and its influences on the boiling evolution an d dynamic behaviors of the coolant and molten clad motion. They also indica te that the multi-dimensional analysis is essential in evaluating hypotheti cal subassembly accidents of LMFRs including a large-scale local blockage a nd a total inlet blockage.