在线加钚模式下的熔盐堆钍铀燃料可持续性研究

Study on the sustainability of thorium uranium fuel in Molten Salt Reactor under on-line plutonium loading model

基于FLiBe载体盐,Th/233U启堆,仅通过在线添加反应堆级钚,以实现熔盐堆233U的自持和焚烧反应堆级钚的能力。采用单栅元模型,分析其在不同熔盐体积比、不同中子损失率下233U的自持和钚的利用性能。研究发现:在熔盐体积占比为10%~85%的较大范围内都可以实现233U自持,其中约43%熔盐体积比下233U增殖效果最佳。与此同时,43%熔盐占比下对钚的依赖最大,在熔盐体积比较小和较大时对钚的依赖较小;在熔盐体积比较小时更有利于钚的利用,其中在熔盐体积比为10%~15%时钚的焚烧率最大,约为75%。此外,中子损失率与钚的依赖近似呈正比关系,对233U自持性能影响较小。

[Background] Thorium-uranium sustainability of molten salt reactor usually relies heavily on online reprocessing technology, which is still immature at the present. [Purpose] The study aims to use reactor-grade plutonium online to achieve 233 U self-sustaining and burn reactor-grade plutonium based on the FLiBe carrier salt and Th/233 U starter reactor. [Methods] Based on Scale6.1, the program of molten salt reactor feeding and reprocessing sequence(MSR-RRS) was developed. The database ENDF/B-VII Library of group 238 was adopted for simulation.Single cell models were used to analyze the performance of 233 U self-sustaining and plutonium utilization at different molten salt volume fraction(VF) and neutron loss ratio. [Results & Conclusions] It is found that 233 U self-sustaining could be achieved in a large range from 10%VF to 85%VF, and 233 U have the best breeding ability at about 43%VF,of which the utilization of plutonium is worst. When the VF becomes smaller or larger, the utilization of plutonium always becomes smaller. It is more beneficial to burn plutonium in the low VF region. When VF is 10%~15%, the burning ratio of plutonium is the highest, corresponding to 75%. In addition, the neutron loss ratio is positively proportional to the burnup of plutonium, and has little influence on the self-sustaining performance of 233 U.