Development of MCNP6 model for HTTR using the explicit random method

Ho, H. Q.   ; Honda, Yuki; Goto, Minoru  ; Takada, Shoji; Ishitsuka, Etsuo   

Coated fuel particles (CFPs) play an important role to the passive safety feature of the high temperature engineering test reactor (HTTR). However, random distribution of the CFPs also makes the simulation become more difficult and therefore affects the quality of the HTGR benchmark assessment. The highly accurate calculation enables the design of a commercial HTGR to operate with low cost and high performance. The purpose of this study was to develop MCNP model for the HTTR by using the explicit random model, namely Realized Random Packing (RRP), to improve the accuracy of the benchmark assessment. The RRP model was validated by comparing with the conventional uniform model as well as the experimental data. The neutronic and criticality calculations were performed by using MCNP6 code with ENDF/B-VII.1 nuclear data library.