Accurate calculation of reactivity changes caused by impact is a key problem to be solved urgently in the design and safety analysis of micro-reactors.In this paper,neutron transport simulation and explicit finite element dynamics simulation based on unstructured-mesh Monte Carlo are combined to study the multi-physical coupling calculation of micro-reactor under the condition of large deformation of dynamic impact.Taking the 85-pin NaK-cooled space nuclear reactor as an example,the time-dependent variation of reactivity in the process of vertical and 45° dip impact is analyzed.The results show that,without considering the uniform density change of fluid and fuel,the keff caused by vertical impact increases by about 8％,while the keff caused by 45° impact increases by about 3％,which were in good agreement with the results in the literature.Under the condition of non-uniform fuel density change,the increase of keff in the two scenarios increased by about 10％and 20％,respectively.The research provides an important theoretical foundation for the critical safety analysis of the space nuclear reactor's launch.
维普
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