~(99)Tc靶件中子学特性及释热率特点的初步研究

99Tc是一种重要的长寿命裂变产物,半衰期长,极易随地下水迁徙扩散.将99Tc嬗变为短寿命或稳定核素,可有效降低其对环境的危害.99Tc在热中子谱下具有较大的吸收截面,采用PWR嬗变99Tc是一种可行途径.为了评估99Tc嬗变靶件对PWR堆芯中子学参数的影响,并为含嬗变靶件的PWR组件热工水力计算提供数据,本文对含99Tc的17×17 PWR组件进行模拟计算,给出了99Tc靶件加入前后,燃料温度系数、慢化剂温度系数的变化规律;计算了稳态工况下99Tc靶件的轴向释热率.相关结论可为PWR嬗变99Tc研究提供参考.

Preliminary Study on the Neutronics and the Heat Releasing Rate Characteristics of 99Tc Transmutation Target

⁹⁹Tc is a kind of important long-lived fission products with a very long half-life, which is easy to migrate with water underground.Transmuting ⁹⁹Tc to short life or stable nuclides will effectively reduce its harm to the environment.As ⁹⁹Tc has larger absorption cross section in the thermal neutron spectrum,it is a feasible way to transmute it in PWRs.In order to estimate the influence on the core neutronics parameters after putting the ⁹⁹Tc target into PWR,and to provide data for the thermal hydraulic calculation of PWR containing targets,the article has caculated fuel temperature coefficient,moderator temperature coefficient before and after putting ⁹⁹Tc into a 17 × 17 PWR assembly and axial heat releasing rate of the ⁹⁹Tc target in steady state condition.The relevant conclusion can provide reference for the continued study of ⁹⁹Tc transmutation in PWR.