乏燃料后处理溶解过程核临界安全初步分析

Nuclear Criticality Safety Analysis in Dissolving Process of Spent Fuel Reprocessing

通过建立合理的空间分布模型,对后处理厂乏燃料溶解不同阶段的核临界安全问题进行分析,同时对重要的核临界安全参数给予影响评价。结果显示,在仅考虑易裂变核素形态转变的理想情况下,溶解初期为最危险状态;温度升高和硝酸浓度增大对系统的影响为负效应,影响均小于4%;可溶中子毒物的加入与燃耗信任制技术的应用能大幅提高系统的经济性,影响均可达到30%。

A rational space distribution model for spent fuel element dissolving at each stage of process in reprocessing plant was formulated. The nuclear criticality on safety issue was studied by calculating numerical model on the process of spent fuel dissolution in consideration of the given plant arrangement. An assessment of the influence of several main critical parameters to the plant safety was given. The calculation results show that the most dangerous status occurs at the initial stage of dissolution when fissile nuclide transforms under ideal conditions. A negative influence to the system is indicated by the increase of temperature and concentration of nitric acid, and the effect is less than 4%. System safety can be improved greatly by the addition of neutron poison or the application of fuel burnup credit, and the effect reaches 30%.