压水堆不同燃耗完整和破损棒燃料芯块氧化特征拉曼光谱研究

Raman characteristic analysis of oxidation of fuel pellets for intact and leaked pressurized water reactors fuel rods with different burnup

为研究压水堆不同燃耗完整和破损燃料棒燃料芯块氧化过程和物相变化,采用拉曼光谱分析技术对燃耗为14 GW·d·t^(−1)和45 GW·d·t^(−1)的完整燃料棒及燃耗为14 GW·d·t^(−1)和41 GW·d·t^(−1)的破损燃料棒燃料芯块的氧化特征进行了分析。结果表明:14 GW·d·t^(−1)和45 GW·d·t^(−1)的完整燃料棒燃料芯块由UO2、U4O9和U3O8组成,相比于燃料芯块的内部区域,芯块边缘显示出更强的氧化性;14 GW·d·t^(−1)和41 GW·d·t^(−1)破损燃料棒燃料芯块发生了重结构,形成柱状晶粒,主要物相为UO2和U3O8。燃耗的加深和燃料棒的破损均促进了燃料芯块的氧化过程,但并不会改变燃料芯块的主要相结构。

To study the oxidation and phase structure of fuel pellets for both intact and leak pressurized water reactors fuel rods with different burnup,Raman spectroscopy was used to analyze the intact fuel rods with 14 GW·d·t^(−1)and 41 GW·d·t^(−1)burnup as well as the leak fuel rods with 14 GW·d·t^(−1)and 41 GW·d·t^(−1)burnup.Evaluation of the reactivity and structural changes of the fuels based on different laser powers are provided locally.The results show that the increase in laser power would not cause oxidation of UO2.The intact fuel rod UO2 pellets with 14 GW·d·t^(−1)and 45 GW·d·t^(−1)burnup consist of UO2,U4O9 and U3O8,and the oxidation of fuel pellet in peripheral zone is higher than that of the internal area.The leak fuel rod UO2 pellets with 14 GW·d·t^(−1)and 41 GW·d·t^(−1)burnup have undergone restructuring and formed columnar grains,which consist of UO2 and U3O8.The increase of burnup and leakage of fuel rods can promote the oxidation of UO2 pellets,but the main phase structure of the fuel pellets will not change.