Core Physics Study On Long-Life Lead-based Reactor

The small,long-life reactor has characteristics of strong transportability,long period of refueling.It can produce electricity for remote communities,isolated island,extreme climate disaster rescue and mining.So it has attracted more and more attention around the word.Lead-based reactor is an important candidate for long-life reactors due to its excellent performance in thermal hydraulics,chemical and inherent security features.A series of design studies have been carried out on the long-life lead-based reactor,but there is still a lot of potential to be excavated in the miniaturization and long-life design of lead-based reactors.How to make full use of optimal design to achieve miniaturization,long-life operation and high economics of the core to meet the demand for future distributed energy remains one of the research hotspots for lead-based reactors.Based on the extensive investigation of the existing small reactor design,core physics study on long-life lead-based reactors was carried out in combination with the physical characteristics of lead-based reactors.The research contents include:(1)Analysis of the key factors in the design of long-life core.Based on an annular channel fuel element model,this paper studied the influence of the neutron spectrum on the critical size,initial fuel loading and bumup characteristics of the core to explore the best.physical design of core minimization under the different energy output demands(power×refueling period).The results showed that there is always a core with optimal neutron spectrum and minimum core size for different energy output demands.When the reactor total energy output demand is greater than 275MWt·Year,the reactor core designed with a fast neutron spectrum has minimum size.When the reactor total energy output demand is less than 275MWt Year,the reactor core designed with a thermal neutron spectrum has the minimum size.The less the energy output demand is,the softer the neutron spectrum for minimum core size should be.(2)Core physics design for a long-life lead-based reactor core with a power generating capacity of 5MWt.A small,long-life lead-based reactor core with a power generating capacity of 5MWt was given firstly based on the results of the neutron energy spectrum.And then the method to reduce the ractivity fluctuation during the life was studied to achieve effectively control of the reactor.Through arranging burnable poisons by zoning,the core optimization design with a small reactivity fluctuation was given and the reactivity control strategy was simplified.Finally,detailed physical analysis of the designed core was carried out and compared with the fast lead-based reactor,it is found that the designed core has advantages of smaller core size,less fuel loading,larger fuel burnup,higher economy.The research results in this paper will provide references for the physical design of small,long-life lead-based reactors.