A Methodology Study for Deep Penetration Shielding Calculations of Research Reactors Based on MCNP Code

MCNP code was used to execute the verification calculations of the shielding design for a research reactor in this paper.Various techniques including geometry splitting,source term simplification,multi-group cross-section and energy cutoff were introduced to optimize the calculation.The result shows that the output value from MCNP coincides well with that from the deterministic methods.Besides,a significant increasing of the computing efficiency up to 70% and a small variance of the run output lower than 10% were obtained as a result of the application of the aforesaid techniques.Moreover,a conclusion can be drawn from the analysis that the method proposed to deal with the deep penetration problems in this paper is found to be applicable to the shielding calculations of other research reactors with thick shielding.