Evolution calculations of fuel for a GFR using MCNPX-C90 and Tripoli-4-D

Burnt calculations were realized for a fuel model based on the technology of the Gas-cooled Fast Reactor, GFR. The fuel design is based on bars. The code MCNPX-CINDER90 and the CSADA method for the burnt calculations were used. Models of homogeneous and heterogeneous fuel assembly were studied; for the burnt calculations of the fuel homogeneous model was considered the tracking of three series (Tiers) of evolution of the fission products. The Tier 1 tracks a reduced group of fission products, the Tier 2 tracks to the arrangement of fission products that are contained in the library of cross sections XSDIR of MCNPX; and the Tier 3 tracks 1325 fission products. The results were compared with those obtained with Tripoli-4-D in function of the calculation methods: 1) Explicit Euler, as method of first order; and 2) CSADA, as method of second order. According to the results was observed that the infinite multiplication factor varies in function of the fission products quantity that are tracked. The calculation time used by MCNPX-C90 with the series Tier 3 is more than double than the used by Tripoli-4-D, therefore this last code has advantage over MCNPX-C90 in the case of neutrons analysis of fast reactors. (Author)