SIMULATION OF CASL 3D HFP FUEL ASSEMBLY BENCHMARK PROBLEM WITH ON-THE-FLY DOPPLER BROADENING IN MCNP6

摘要

An On-the-Fly Doppler broadening methodology has been applied in a neutronics simulation of a single fuel assembly (problem 6 of the CASL/VERA Core Physics Benchmark Problems) using MCNP6. HFP temperatures and densities were taken from results of a coupled neutronic-TH computation with the neutron transport code MPACT and the subchannel TH code COBRA-TF. An MCNP6 input file with over 13000 cells with independent temperatures and densities was constructed from a template input file for CASL/VERA problem 3 (3D HZP full assembly). OTF Doppler broadening coefficients for the 54 unique isotopes of the problem were generated using the routines provided in the MCNP6 distribution. HZP OTF MCNP6 results are compared with published benchmark results, and results for 3D HFP assembly simulations are compared with neutronics results from the coupled MPACT/COBRA-TF simulation.