UO_2-Zr弥散燃料板氧化扩散机理研究

UO2-Zr弥散燃料板的氧化过程包括包壳与冷却剂的氧化反应和芯体中弥散的UO2燃料微球氧原子扩散过程。本文通过直接求解球坐标系下的氧化扩散方程,得到UO2燃料微球高温下向芯体中氧原子扩散强度的解析式,该式与实验数据符合良好,并结合锆水反应与UO2燃料微球高温氧原子扩散效应构建了UO2-Zr板的氧化扩散模型。新模型能预测不同的氧化结构、芯体中更高的氧原子浓度以及相对较低的氧化吸氧量,为UO2-Zr板严重事故早期行为的研究提供了理论基础。

Mechanism of Oxygen Diffusion in UO2-Zr Dispersion Plate-type Fuel

The oxidation of UO₂-Zr dispersion plate-type fuel consists of two processes: Zr-water chemical reaction and oxygen diffusion from dispersed UO₂ fuel particles in fuel meat at high temperature. The oxygen diffusion equation in one-dimensional spherical coordinate was calculated directly in this paper to acquire analytical solution of diffusion intensity from UO₂ fuel particles to Zr fuel matrix, and analytical solutions suit well with experimental results. A new UO₂-Zr oxidation model which combines Zr-water chemical reaction and oxygen diffusion process in plate-type fuel was developed in this paper and the calculation results indicate different oxidation structures, larger oxygen concentration and smaller oxygen absorption from water in plate-type fuel supply theoretical fundamental for severe accident research on the early phase performance of UO₂-Zr dispersion plate-type fuel.