کوروش قیصری

In this paper, Burnup fuel assemblies of VVER1000 reactor TVSA model and Bushehr reactor have been studied in its second stage of fuel loading using MCNPX2.6 computational code. Also, the cross-sections of neutron reactions at working temperatures are calculated using the NJOY code. In the design of the TVSA assemblies, the standard burnable absorbers material of CrB2 has been change to gadolinium oxide burnable absorber rods (Gd2O3) and, in addition, they have decreased, and the length of the reactor fuel cycle has increased from 12 months to 18 months. As a result of these changes, the burnup increased significantly and in addition, the uniform distribution of power was achieved at the core of the reactor.