Comparison of Methods for Calculating the Neutronic Characteristics of a VVER-1200 Fuel Assembly
This article presents the results obtained by neutron-physical calculation of a VVER-1200 fuel assembly using the multi-purpose three-dimensional continuous-energy Monte Carlo particle transport code Serpent 2. The study compares the neutron-physical characteristics calculated using two methods. The existence of several techniques makes it doubtful that they are all equivalent to each other. If this is not the case, then from the available methods of calculating the reactor campaign, you can choose the most reliable one, that is, the one that corresponds to real operating conditions. Under such conditions, ageing is performed to reduce the concentration of neutron absorbers (<sup>135</sup>Xe, <sup>135</sup>I). The burnout of fuel assemblies with a 30-day exposure and a model refueling procedure and burnup without a refueling procedure (continuous process) were considered, infinite neutron multiplication factors have been determined for the methods, and also the dependence of the concentration of important nuclides from the standpoint of neutron-physical characteristics (strong absorbers) on the depth of fuel burnup. The concentration of <sup>155</sup>Gd was also monitored, it turned out that it burns out in the same way in the framework of the two methods. It is concluded that the reasons for the discrepancy between the values when using different methods are the different accumulation of samarium isotopes in the process of simulated burnup.