U-10Mo/Zr单片式燃料元件堆内稳态热-力学性能研究

Research on In-Pile Thermo-Mechanical Performance for U-10Mo/Zr Monolithic Fuel Element under Steady Condition

本文建立了U-10Mo/Zr单片式燃料元件的辐照性能模型以及热-力学本构关系,采用有限元方法进行非均匀辐照场中燃料元件稳态热-力学性能的数值模拟,获得并分析了U-10Mo/Zr单片式燃料元件温度、形变和应力的分布特点及变化规律。研究结果表明,燃料芯体厚度增量在芯体和包壳结合面附近达到最大,主要受到燃料辐照蠕变的影响;在较低燃耗条件下,燃料芯体高温辐照肿胀模拟结果与低温辐照肿胀试验结果相当;燃料芯体边角区域和包壳端面外侧区域存在应力集中。

In the paper,the models of irradiation performance and thermo-mechanical constitutive relations of U-10 Mo/Zr monolithic fuel element were established.With the finite element method,numerical simulation of fuel element thermo-mechanical performance under steady heterogeneous irradiation condition was conducted,the distribution and evolution characteristics of temperature,strain and stress in U-10 Mo/Zr monolithic fuel element were acquired and analyzed.The results showed that the thickness increment of the fuel pellet becomes largest near the interface between fuel pellet and cladding,predominantly affected by fuel irradiation creep.Under the low burn-up conditions,the simulation result of fuel pellet swelling at high temperature condition equals the irradiation test results at low temperature.There are stress concentrations in the corner area of the fuel pellet and the outer area of the cladding end surface.