U-Zr合金燃料与铅、铋及其合金静态相容性研究

Study on compatibility between U-Zr alloy fuel with lead, bismuth alloy

U-Zr合金燃料与液态铅、铋及其合金静态相容性是铅铋冷却反应堆燃料论证及设计的重要依据。试验选取600oC,保温1 000 h范围内,开展了U-Zr合金燃料与铅、铋及其合金静态相容性的研究。采用扫描电镜(Scanning Electronic Microscopy,SEM)及X射线衍射(X-ray Diffraction,XRD)分析了U-Zr合金燃料与铅铋等合金的界面反应情况,试验结果表明:U-Zr合金样品在铅铋合金的长时间(1 000 h)作用下,产生了不同程度的侵蚀现象,侵蚀程度可达到mm级。纯铋、纯铅、铅铋、铅锡、铅铋锡等均对U-Zr芯块有一定程度的侵蚀,其侵蚀程度排序约为Bi>Pb-Bi>Pb-Bi-Sn>Pb≈Pb-Sn。U-Zr芯块的腐蚀机理为溶解和共晶形成金属间化合物的综合过程,U和Pb、Bi分别能够形成金属间化合物UPb_3和UBi_2。U-Zr芯块的侵蚀程度取决于U和Zr在冷却剂成分中的固溶度和共晶反应速率。

[Background] Lead-bismuth is the advanced reactor coolant. The corrosion compatibility between U-Zr alloy fuel and liquid lead-bismuth eutectic alloy (LBE) is the important basis for fuel verification and design of LBE cooled reactor.[Purpose] This study aims at the corrosion mechanism and compatibility of U-Zr alloy and liquid lead-bismuth eutectic alloy.[Methods] Experimental temperature was set at 600℃ and heat preserved for 1 000 h, the corrosion compatibility and interfacial reaction of U-Zr alloy fuel with liquid lead (bismuth) alloy were investigated by both the scanning electron microscope (SEM) and the X-ray diffraction (XRD).[Results] The results show U-Zr alloy was eroded more or less after long-term interaction with bismuth, lead, LBE, lead-tin and lead-tin. The order of erosion degree is as Bi>Pb-Bi>Pb-Bi-Sn>Pb≈Pb-Sn. The depth of U-Zr alloy eroded by liquid coolant reached the millimeter level.[Conclusions] The corrosion mechanism of U-Zr alloy is a comprehensive process of dissolution and eutectic formation of intermetallic compounds. Intermetallic compounds UPb3 and UBi2, can be formed by the interaction of uranium with lead and bismuth, respectively. The degree of U-Zr alloy erosion depends on the solubility and the eutectic reaction rate of U, Zr in the coolant.