加速增产核燃料的天然安全“核热泉”快中子增殖堆

Accelerating fissile fuel breeding in FBR with natural safety features

为保证21世纪中国经济的持续稳定地高速增长,必须充分发挥核能的巨大潜力,使之配合其他可再生能源同步增长,及早大规模替代煤炭等化石能源。由于目前国内大量兴建的核电站以压水堆为主,需要消费大量天然铀资源,倚靠廉价铀供应难于维持长期增长,必须依靠快中子增殖生产人造裂变燃料——钚,才能摆脱天然铀原料短缺的束缚。然而,传统的快中子增殖堆的核燃料增产速度较慢,难于配合中国核电的高速增长。本文介绍一种先进快中子增殖堆(AFBR)方案,其中利用在线连续换料的空心球形燃料元件,依靠载热剂的出入口之间的温度差实现满功率自然循环,可以成倍地提高燃料比功率与核燃料增殖速度。本快中子增殖堆改进了俄罗斯称为"天然安全"的BREST铅冷快堆设计方案,成为无须人为控制的"核热泉",它能在不设置加压泵及高位铅池的情况下,自动按外部负荷需要供应必要的热量,完全依靠自然循环将全部裂变热能及停堆后堆芯余热散出,不至对环境产生放射性污染。

To guarantee the rapid growth of the Chinese economy in 21st century,nuclear energy should be fully exploited,together with other renewable energies to replace coal and other depletive fossil fuels.Unfortunately,the major Chinese nuclear power plants under construction are mostly PWRs that would consume a lot of natural uranium during their operations.The availability of cheap natural uranium could seriously constraint the Chinese nuclear power development,unless artificial fissile fuel—plutonium is supplied from fast breeder reactors.The fissile nuclei production rate in the traditional fast breeders,however,seems too slow to match the rapid growth of nuclear power.A concept of the advanced fast breeder（AFBR） is introduced,therefore,to greatly accelerating the fissile fuel breeding process.In said breeder,the spherical hollow fuel elements and on-line refueling are adopted.The coolant flows horizontally through the annual fuel bed and bring out the full-fission power with natural circulation generated with the temperature difference between the inlet and outlet coolant flow.In such case,the fuel breeding rate could be greatly increased as the specific thermal power of the fuel inside the reactor core.The said AFBR is an improvement to the Russia-designed BREST FBR.It could transport,without the lead pump and high-elevation lead pool,all the fission heat solely via natural circulation under full power,as well as the decay heat after reactor shut-down,working just as a nuclear hot spring.No radioactivity would be released to the environments under any outside disasters.