Multi-physics simulation of nuclear reactor core by coupled simulation using CUPID/MASTER

In order to visualize a realistic nuclear reactor behavior for abnormal control rod operation accident scenario, a multi-physics approach was performed. Multi-dimensional thermal hydraulics in the reactor core was calculated by coupling the reactor kinetics code. The reactor core for thermal hydraulic analysis is obtained by the CUPID which is aimed for the analysis of transient two-phase flows in nuclear reactor components by Korea Atomic Energy Research Institute (KAERI). In the present paper, a multi-physics simulation was performed by coupling CUPID with a three dimensional neutron kinetics code, MASTER which is a two-group, three-dimensional neutron diffusion code for microscopic depletion, xenon dynamics, on-line Departure of Nucleate Boiling (DNB) analysis and kinetics calculation. The MASTER code is merged into the CUPID code as a dynamic link library (DLL). The OPR1000 reactor core was taken into account by adopting porous media approach. Two hypothetical accident scenarios for malfunction of control element assembly (CEA) were numerically reproduced; (i) CEA drop and (ii) ejection accident. The coupled simulation shows a reasonable and consistent thermal hydraulic behavior. The multi-dimensional thermal hydraulics results show asymmetric temperature distribution which was not obtained by the best-estimated thermal hydraulics code before.