Study On Uncertainty Analysis Method Of Plate-Type Fuel Reactor Core Physics

Compared with rod-type fuel elements,plate-type fuel elements have higher power density and better fuel stability,plate fuel elements are often used in experimental research reactors or integrated reactors.In the process of core physics calculation of the two-step method,the group cross section generated by uniform components will be affected by the interference of the hardened energy spectrum,so the four group constants are used for core physics calculation of the plate-type fuel reactor.At present,there are few researches on the uncertainty analysis of plate-type fuel reactor,so it is of great significance to carry out the uncertainty analysis of plate-type fuel reactor.Based on plate-type fuel reactor as the research target,this paper refer to Japanese Research Reactor JRR-3 component structure of core do preliminary design,the uncertainty in the process of the reactor core physics calculation is divided into three sources:calculating program uncertainty,nuclear data uncertainty and input parameters.According to different sources,the corresponding uncertainty analysis process is designed.Monte Carlo calculation results were used to verify and analyze the uncertainty of effective propagation factor in the two-step reactor core physical calculation program.The uncertainty of nuclear data to effective multiplication factor is analyzed by perturbation method.For the uncertainty of input parameters to effective multiplication factor,a set of uncertainty analysis process is designed,first by sensitivity analysis to choose the effective multiplication factor influential parameters,then the uncertainty of the candidate parameters is analyzed by parametric statistics,nonparametric statistics and other method.Finally,the various methods are evaluated by comparing the calculation process and uncertainty analysis results.In addition,the uncertainty analysis process of input parameters for effective propagation factor was extended to the uncertainty calculation of control rod value,and evaluation of different uncertainty analysis methodsThe analysis results show that the error difference between the two-step method and the Monte Carlo program is 0.05%.The nuclear reaction cross section of ²³⁵U in the nuclear data and the nuclear reaction cross section of ¹H in the moderator have great influence on the effective proliferation factor.The enrichment degree,fuel density,fuel inner diameter and outer diameter of cladding have great influence on the effective propagation factor.The relative uncertainty of effective proliferation factor caused by nuclear data is 0.54%,and the relative uncertainty of effective proliferation factor caused by input parameters is 0.20%.The uncertainty caused by nuclear data is higher than that caused by input parameters.Parametric statistical method and non-parametric statistical method are similar in the calculation results of tolerance interval of effective multiplication factor.When calculating tolerance interval of control rod value,emphasis should be given to the influence of formula error transfer.