GAMMA+ Simulation of Phase 1 Exercise 2 of the OECD/NEA MHTGR-350 Benchmark

Sponsored by OECD/NEA, a benchmark study on the prismatic coupled neutronics/thermal fluids transient for the MHTGR-350 core was initiated in 2012. The benchmark consists of three phases, i.e., steady-state (Phase 1), transient-state (Phase 2) and depletion problems (Phase 3). Phase 1 has three exercises. Exercise 1 deals with neutronics stand-alone calculation whereas Exercise 2 focuses on thermo-fluid stand-alone calculation. The coupled simulation is defined in Exercise 3. Korea Atomic Energy Research Institute (KAERI) is participating in Phase 1 Exercise 2 using the GAMMA+ code. The present paper summarizes the GAMMA+ model and results of Phase 1 Exercise 2 which contains the steady-state thermo-fluid simulation of the MHTGR-350 core. In this work, the GAMMA+ modeling and calculation results were presented for Phase 1 Exercise 2 of the OECD/NEA MHTGR-350 benchmark. Four cases were considered with two different grid size models. The results of the GAMMA+ calculations were found to be reasonable. The results were submitted to the benchmark organizer. The international comparison is on-going and the final OECD/NEA publication will be issued later.