Experimental Study On Thermal Properties Of Lead Bismuth Eutectic Alloy

Lead-based fast reactors(LFR)have many advantages,such as outstanding economy,inherent safety,and multi-scene applicability.LFRs have great development potential and they are considered to be the first fourth-generation reactor to be the first to achieve industrial demonstration.In LFRs,the accelerator driven subcritical system(ADS)is considered to be the most effective way to improve the utilization rate of nuclear fuel and one of the key technologies for the sustainable development of nuclear energy because of its good neutron economy and transmutation ability.Lead bismuth eutectic alloy(LBE)is the primary candidate material for ADS system's spallation target and coolant.Its specific heat capacity and thermal conductivity play an important role in the thermal-hydraulic design of the reactor.However,the existing data of LBE's specific heat capacity and thermal conductivity are limited,and the data still have the problem of accuracy(the measurement error of specific heat capacity is more than 7%,and the measurement error of thermal conductivity is more than 10%).Hence,more sufficient and accurate data are needed to provide data basis for the safety design and heat exchange research of the reactor.In this thesis,the specific heat capacity and thermal conductivity of LBE are studied by experimental measurement.In the study of specific heat capacity,differential scanning calorimetry(DSC)was used to measure the specific heat capacity of LBE in the range of 30?600?,and the relationship between specific heat capacity and temperature was obtained.Through the reliability analysis of the measurement method,this thesis verifies that the measurement error of this method is about 0.66%,and the measurement accuracy has been greatly improved by compared with the existing data measurement error(7%).In addition,the uncertainty analysis of the specific heat capacity data of LBE shows that under 95%confidence probability,the maximum combined uncertainty of the data is 1.83%,and the maximum expanded uncertainty is 3.66%(k=2).In the study of thermal conductivity,laser flash method(LFA)was used to measure the thermal conductivity of LBE in the range of 200?600?.As a result,the maximum measurement error of LBE is less than 6.5%,the maximum composite uncertainty of thermal conductivity data is 2.75%,and the maximum expanded uncertainty is 5.5%(k=2).In this thesis,the specific heat capacity and thermal conductivity of LBE are accurately measured,and the obtained experimental data can supplement the existing database of LBE's thermal properties.The results of this study can not only provide the basis for the study of the heat transfer behavior of the reactor's coolant,but also provide the data support for the thermal-hydraulic design of the LFRs.Therefore,this thesis has great significance for the development of the lead-based fast reactor with liquid lead bismuth eutectic alloy as the coolant.