Application of global variance reduction method to calculate a high-resolution fast neutron flux distribution for TMSR-SF1

  • Pu Yang
  • Ye Dai
  • Yang Zou
  • Rui Yan
  • Bo Zhou
  • Shi-He Yu
  • Yu-Wen MaEmail author


The solid fuel thorium molten salt reactor (TMSR-SF1) is a 10-MWth fluoride-cooled pebble bed reactor. As a new reactor concept, one of the major limiting factors to reactor lifetime is radiation-induced material damage. The fast neutron flux (E > 0.1 MeV) can be used to assess possible radiation damage. Hence, a method for calculating high-resolution fast neutron flux distribution of the full-scale TMSR-SF1 reactor is required. In this study, a two-step subsection approach based on MCNP5 involving a global variance reduction method, referred to as forward-weighted consistent adjoint-driven importance sampling, was implemented to provide fast neutron flux distribution throughout the TMSR-SF1 facility. In addition, instead of using the general source specification cards, the user-provided SOURCE subroutine in MCNP5 source code was employed to implement a source biasing technique specialized for TMSR-SF1. In contrast to the one-step analog approach, the two-step subsection approach eliminates zero-scored mesh tally cells and obtains tally results with extremely uniform and low relative uncertainties. Furthermore, the maximum fast neutron fluxes of the main components in TMSR-SF1 are provided, which can be used for radiation damage assessment of the structural materials.


TMSR-SF1 Fast neutron flux Global variance reduction MCNP 


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Copyright information

© China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, Chinese Nuclear Society and Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  • Pu Yang
    • 1
    • 2
  • Ye Dai
    • 1
  • Yang Zou
    • 1
  • Rui Yan
    • 1
  • Bo Zhou
    • 1
    • 2
  • Shi-He Yu
    • 1
  • Yu-Wen Ma
    • 1
    • 2
    Email author
  1. 1.Shanghai Institute of Applied Physics, Chinese Academy of SciencesShanghaiChina
  2. 2.University of Chinese Academy of SciencesBeijingChina

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