Analysis Of Burnup Performance For A Molten Chloride Salt Fast Reactor Based On Thorium Fuel

Compared with traditional light water reactors?LWR?,molten salt reactor?MSR?,as one of the the advanced Generation IV reactors,has outstanding advantages in terms of inherent safety,economy,fuel effective utilization and proliferation resistance.MSR usually adopts liquid fluorine molten salt or chlorine salts as fuel carrier and coolant,and designs of a series of MSRs such as molten fluoride salt fast reactor?MSFR?,molten fluoride salt reactor and molten chloride salt fast reactor?MCFR?have been proposed.The MCFR has obvious advantages in terms of TRU solubility,neutron spectrum and melting point,leading to a better breeding performance than the MSRs with fluoride salt.At the same time,due to less production of long-life radioactive transuranium nuclides of Th-U fuel than U-Pu fuel,MCFR based on the Th-U fuel cycle will be beneficial to the depletion of TRU.Therefore,it is important to perform a research on the breeding and transmutation of MCFR,which is expected to provide a reference for the management and disposal of spent fuel.In this paper,the Molten Salt Reactor Reprocessing Sequence?MSR-RS?is verified by simulating the core structure of MSFR.It is found that the evolution of nuclides calculated from the MSR-RS is in good agreement with the reference under the four types of start-up fuels,which indicates that the MSR-RS program can simulate the burnup of molten salt fast reactor.Then,this paper aims to optimize the composition and reprocessing mode of the molten salt to improve the breeding and burnup performance of the reactor,and to provide a single-zone MCFR design.Based on the MSR-RS program,the effects of different carrier salt and starting fuel on burnup performance are analyzed and the composition of molten salt is optimized.Then,batch reprocessing and on-line reprocessing are introduced to improve burnup performance.After the optimization,the burnup-time is extended to 31 years,the burnup level is increased to 210 GW·d/t,the production of²³³U is 8.3 tons,and finally 12 tons of TRU is consumed corresponding to transmutation rate of 62.1%.The results indicate that NaCl is a more suitable carrier salt for MCFR,and MA in the TRU also helps to improve the breeding performance.With a batch reprocessing mode,the core can achieve a high burnup meaning a low requirement for the reprocessing system.In addition,based on the simulated results of molten salt composition,this paper analyzes the influence of core structure and ³⁷Cl enrichment under the conditions of on-line reprocessing,and a double-zone MCFR is proposed.The results show that the reactor has great neutron economy and breeding performance when the thickness of fertile zone is 70 cm and the ³⁷Cl enrichment is 97%,and there is no significant effect on the breeding performance with further increasing of fertile zone and the ³⁷Cl enrichment.The optimized double-zone MCFR has a large negative temperature coefficient of reactivity,a great breeding ratio and a transmutation efficiency.Its doubling time is 20 years,and the transmutation amount of TRU and MA are 153kg/?GW·a?and 371 kg/?GW·a?,respectively.