Neutronics Of Fast Spectrum Critical Experimental Facility Based On Two-step Method

As the main type of fast reactor in the future development of nuclear energy,neutron calculation is very important for core design and safety analysis.The fast spectrum critical experimental facility is mainly used for the study of fast spectrum core design,core neutron behavior and nuclear data acquisition.At present,there is some progress in the research of fast spectrum critical experimental device at home and abroad,but there is little research on the exact neutron simulation of fast spectrum critical experimental device with square component plate fuel.The fast spectrum and few group cross section calculation software TULIP and the few group transport calculation software LAVENDER were developed by the Nuclear Engineering Computational Physics Laboratory of Xi ’an Jiaotong University and integrated into Loong SARAX.Loong SARAX can be used to study its square assembly plate fuel fast spectrum critical test facility.In this paper,the small group section calculation program TULIP and the steady-state neutron analysis program LAVENDER are used to analyze two square component plate fuel critical test devices,the MZA and SNEAK.Firstly,it is about the deduction of the most important theoretical models before and after the two models before and after the spaceweighted mixing treatment of nucleon number density involved in this study,which mainly includes the calculation model of resolvable and inresolvable resonance and the collision probability model in inhomogeneous medium.Considering that the mean free path of neutron in the fast spectrum core is relatively long,the local resonance self-screen effect is weak.The global coupling effect of neutron energy spectrum is strong,so it is reasonable to blend the plate fuel into uniform fuel assembly by volume share mixing.The Monte Carlo reference solutions are constructed for the MZA sodium cold fast spectrum critical experimental device and SNEAK sodium cold fast spectrum critical experimental device.Conduct TULIP calculation on fuel assemblies and structural components in MZA and SNEAK sodium cool-fast spectrum critical experimental device,and then compare the small group cross sections generated by TULIP with those calculated by Open MC after component modeling calculation alone.The results of interprogram comparison showed that the microcross sections of the few groups treated by TULIP were consistent with the microcross sections calculated by Open MC except for the influence caused by the large statistical error at the low energy segment.LAVENDER based on cuboid grid-based SN segment block method is used to calculate the small group core.Due to the complex structure of the MZA fuel assembly,the maximum deviation of the effective breeder factor after processing is greater than that after SNEAK fuel assembly processing.When the spatial weighted mixing of the axial plate fuel square component is carried out,smaller errors will be introduced for the component with high repeatability and weak non-uniformity,while larger errors will be introduced for the component with strong heterogeneity.The maximum deviation of the calculation results of safety rod and control rod value and the maximum deviation of the calculation results of typical component reactivity are small.At the same time,the calculation results of core power distribution show that the maximum error is within the reasonable range.