Neutronics calculations and analysis of ITER test blanket module lay the foundation for the design, construct and experiment of ITER. In this paper, the realistic 3D neutronics calculations of the dual functional lithium lead-test blanket module (DFII-TBM) have been carried out by means of the 3D MOC code and the SPN code, which are both deterministic methods and developed by NECP lab, adopting the multi-group nuclear data library FENDI/MG-2.1. The main features of the TBM nuclear response are assessed, paying a particular attention to the neutron flux and tritium production rate.

The 3DMOC code is a coupling a 3D method of characteristics (MOC) to the common geometry module. It could calculate the flux throughout three-dimensional systems by the MOC, which has been proved a very flexible and effective method for the neutron transport calculation in a complex geometry. In this code, a modular ray tracing technique is adopted to reduce the amount of the ray tracing data and the Coarse Mesh Finite Difference (CMFD) acceleration method is employed to save computing time, which could well solve the difficulties when applying MOC in three-dimensional geometries.

The SPN code is another three-dimensional Boltzmann transport equation calculation code. The simplified PN method is used to treat the directional variable, and the Nodal method treats the spatial variable. Consequently, this code has an advantage in shorting computing time when applied to big geometry problems.

Considering the big geometry of DFII-TBM and the large number of the cross sections of nuclear data library FENDI/MG-2.1, a two-step approach is adopted. Firstly, the DFII-TBM is dissected into some typical independent parts. 3D calculations are performed on these parts respectively with 3D MOC code and FENDL/MG-2.1 library to obtain the detailed heterogeneous flux distribution. Then the homogenization is carried out to calculate the average homogeneous cross sections, followed by the use of homogeneous cross sections to calculate the flux distribution throughout the DFII-TBM with SPN code.

The results obtained are herewith presented and critically discussed.

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