Neutronics Experiment And Numerical Simulation Study Of Dual Functional Lithium-Lead Blanket

A fusion blanket is an important part of a fusion reactor;it has the functions of tritium production,energy conversion,and shielding.It is one of the key components to be considered in the design of neutron production and analysis of the fusion reactor.Liquid lithium-lead blanket is a very promising candidate for fusion blanket.It has the advantages of high tritium breeding rate,online tritium extraction and high thermal efficiency.The concept of lithium-lead fusion blanket has attracted much attention internationally.Among them,the Dual-Function Lithium-Lead(DFLL)blanket is a conceptual design with high tritium breeding performance for fusion reactor proposed by FDS team of the Institute of Nuclear Energy Safety Technology,Chinese Academy of Sciences(FDS team).The DFLL blanket can be used to demonstrate and validate the technology of quasi-static lithium-lead and the dual-cooled lithium-lead breeder blanket.The design of fusion blanket mainly relies on neutronics(numerical simulation).However,the calculation accuracy is affected by many factors such as the calculation software,nuclear database,and the precision level of the simulation model.In order to ensure reliable operation of the fusion reactor,it is necessary to verify the accuracy of the numerical simulation through neutronics experiment.In this work,multiple neutronics parameters have been measured using neutronics experiment mock-up of DFLL blanket(abbreviated as DFLL mock-up)according to DFLL blanket design.Through the comparative analysis of calculated over measured results,the calculating accuracy of neutronics parameters for DFLL mock-up have been verified.Based on the verification,the calculation analyses and design optimizations of neutronics performance for DFLL blanket were carried out using the Chinese Fusion Engineering Test Reactor(CFETR)model.The research work includes the following three parts:(1)Neutronics experiment research based on DFLL mock-up.Neutron parameters such as tritium production rate and activation reaction rate were measured using the DFLL mock-up based on high intensity D-T fusion neutron generator(HINEG).In order to resolve the technical problem associated with the method of a particle monitoring of neutron source intensity of a rotating target,a combined method of niobium activated foil and 238U fission ionization chamber was used.A high-precision of on-line source intensity data was obtained successfully with an uncertainty less than 4.20%.Based on this result,the tritium production rate and activation reaction rate at different positions on the central axis of the blanket were measured using Li2CO3 pellet and activation foils group respectively.The results show that the maximum uncertainty of tritium production rate was 4.83%,the maximum uncertainty of activation rate measurement was 5.38%.(2)Neutronics simulation verification based on the obtained neutron experimental data.According to the design of DFLL blanket mock-up,a detailed neutronics model was established by using Super Multi-functional Calculation Program for Nuclear Design and Safety Evaluation(SuperMC),and the calculation results corresponding to the experiment were obtained combined with JEFF3.2 and FENDL3.1 database.The accuracy of the neutronics calculations was evaluated through the "Ratio of Calculation to Experiment=(C/E)" analysis.The results show that the C/E of activated foil reaction rates are about 0.78-1.10,the C/E of tritium production rates are about 1.04-1.08.The obtained results indicate that the calculation results matched well with the experimental results.(3)The optimization design of DFLL blanket based on fusion reactor.In this study,a neutronics model of CFETR employing DFLL blanket has been established by using SuperMC.Through the quantitative/sensitivity analysis of DFLL blanket structure design on total tritium breeding performance,the sensitivity trend and influence law of different blanket structures on the tritium breeding performance were obtained.At the same time,it was found that the first wall armor decreased the tritium breeding performance the most.By optimizing the DFLL blanket layout and comparing the tritium breeding performance of various first-wall armors,an optimized design scheme for DFLL blanket that can satisfy the tritium self-sufficiency requirement of fusion reactor has been proposed.In summary,the accumulated high-intensity neutron source experimental experience through the DFLL module neutron experiment will provide valuable experience for the large-scale blanket module neutron experiment in the future.The comparative analysis of experiments and calculations has verified the accuracy of the neutronics simulation and calculation for lithium-lead blanket which provides a basis for the neutronics analysis and optimization of DFLL blanket in the whole reactor.At the same time,the sensitivity trend and law analysis of DFLL blanket on tritium breeding performance.The neutronics analysis and optimization of the whole reactor provide a strong reference and technical support for the development and application of the blanket technology of the Chinese Fusion Engineering Test Reactor.