Study On Modeling Method And Influencing Factors For Reactor Core With Thin Film Fuel Element

Thin-film fuel element is a new type of reactor fuel element whose thickness of nuclear fuel film is on the order of micron and the difference of the geometrical order of fuel and its attached structural material being thousands of times.At present,Monte Carlo method and two-step method are often used in reactor core modeling calculation.The Monte Carlo method is based on the statistical calculation of sample number,while assembly calculation in two-step method adopts the idea of assembly homogenization approximation.For the special structure of fuel element with thin film,the study of appropriate core modeling calculation method has a certain significance for the subsequent research and design work,and also has a certain reference value for the study of other complex structure of fuel element modeling method.Based on membrane type fuel element component and its corresponding control drum component,in this paper,the membrane type fuel element core has carried on the preliminary design,and uses the KENO program and NEWT/RELAP5-3D two-step procedure respectively for the detailed modeling calculation of membrane fuel core,as well as to the influence factors and the choice of calculation parameters of each program modeling calculation are analyzed.In addition,from the perspective of calculation accuracy and calculation speed,the difference between different component modeling schemes in NEWT/RELAP5-3D modeling and KENO reference calculation results is also studied by taking the critical condition of thin-film reactor core as the research object.The applicability of Monte Carlo modeling method and two-step modeling method to the modeling of thin film fuel element core is analyzed and evaluated.The results show that the Monte Carlo program KENO and the two-step program NEWT/RELAP5-3D can realize the exact modeling calculation of the thin-film fuel element core under the condition of choosing appropriate calculation parameters.The deviation between the core effective proliferation factor calculated by the two-step program NEWT/RELAP5-3D and the reference result calculated by KENO is within 10 pcm,and the cost of calculation time is also small.If the grid number division of fuel assembly calculation is increased,the deviation between the results of two-step method and KENO reference calculation can be within 2pcm.In addition,KENO program is recommended to run 7500 generations with 10000 particles rather than excessively high particles for core calculation of thin-film fuel element reactor.The component computing program NEWT recommends selecting appropriate computational grid and circle approximation parameters in modeling calculations and using the associated accelerated computing capabilities.