摘要
1 Introduction Neutronics design for China HCSB TBM is one of the most important designs in TBM design activities due to offering the input parameters for analysis and calculation of other systems such as thermal-hydraulics, activation, radioactive safety of environment, shielding and ventilation and so on. China HCSB TBM modulet is designed as a module with 3 × 3 sub-modules which is more fixed and safe than that in single module but more structural complex (See Fig. 1 ) . For this modularized TBM, a 3-D neutronics calculation by MCNP code should really been considered.