Improvement and Application of SARAX-FXS Code in Calculation of Heterogeneous Fast Reactor Core

The SARAX-FXS code is a calculation program based on the deterministic method. It has the capabilities of calculating neutron spectra and homogenized cross sections of fast reactor analysis. Since the heterogeneous effect within the assembly was not negligible in fast reactor system, the collision probability method (CPM) with one-dimension slab and cylinder geometry was introduced into the SARAX-FXS code to obtain the homogenized cross sections with this one-dimension geometry. Meanwhile, in order to conserve the reaction rate after energy group condensation, the super-homogeneous (SPH) factor was also implemented in the calculation. To verify the development of the code, the MET-1000 benchmark loaded with metallic fuel was chosen as the verification case. Compared with the reference solutions, the eigenvalue calculated by SARAX-FXS with CPM shows the high accuracy with 100-200 pcm relative deviation. Meanwhile, the whole core calculation shows that the application of SPH factor could enhance the accuracy about 300 pcm and the root-mean-square error of power distribution could decrease from about 3% to 1%.