基于TRISO燃料的小型压水堆研究

Studies on the Small Pressurized Water Reactor Based on TRISO Fuels

目前世界上运行的大部分压水堆都采用二氧化铀(UO2)作为核燃料,锆合金作为包壳.该技术虽然成熟,但在高温下仍存在一定缺陷.新开发的TRISO(Tristructural-isotropic)燃料可以长时间在1 600℃的温度下保持燃料和包壳的完整性,防止裂变产物释放到环境中,在压水堆中使用TRISO燃料替代常规UO2芯块燃料可以大大提高反应堆的安全性.本研究使用TRISO包覆颗粒燃料的小型压水堆,对不同富集度组件排列下的有效增殖系数、堆芯换料周期、中子通量分布等进行分析讨论,并比较2种燃料棒在反应堆正常运行环境下的温度分布.计算结果表明,从换料周期、通量展平、燃料的中心最高温度这3个方面看,在小型压水堆中采用TRISO燃料棒替代常规UO2燃料棒是可行的,使用TRISO燃料的堆芯具有更优异的安全性.

At present,most of pressurized water reactors （PWR） use UO2 fuel pellets as nuclear fuels in the world. Although fuel pellets are utilized widely,they suffer from some defects under high temperature. The newly developed tristructural-isotropic（TRI- SO） fuel can maintain the integrity of the fuel and cladding,which is able to prevent the fission products from being released to the environment at a temperature of 1 600 ~C for a long time. Therefore,the safety of the reactor can be significantly improved by using TRISO fuel instead of the conventional UO~ pellet fuel in PWR. In this paper, a small pressurized water reactor using TRISO fuel was considered. The effective multiplication factor under different uranium enrichment, the refuel cycle, and the neutron flux distribution were discussed. The temperature distributions for two kinds of fuel rods in the reactor were compared. Calculation results show that, according to the fuel reloading length, flux flatted, and temperature distribution, using TRISO instead of conventional UO2 fuel rods is feasible and safer in the small pressurized water reactor.