Brannerite glass ceramic wasteforms for immobilisation of nuclear fuel residues.

该项目旨在满足处理塞拉菲尔德场现有受损和降解的核燃料材料的要求，将这些高放射性废物固定在适合长期储存和最终处置的玻璃陶瓷废料中。这些材料的范围从湿污泥到干燥的颗粒状材料。目前，还没有公认的废物处理路线或这种材料。我们建议为此目的开发一套新型的微晶玻璃废物形式，以合成褐铁矿，UTi2O6为基础。燃料残留物主要是96%的UO2，3%的裂变产物和1%的钚以固溶体的形式溶解。已有研究表明，即使在阿尔法衰变引起的辐射非晶化之后，经过地球化学作用的天然矿物褐铁矿仍能保存其铀储量达数亿年之久。天然褐铁矿已被证明含有高达4wt%的水，这使人们相信合成褐铁矿废液将与湿燃料残渣的处理兼容。该项目将设计和开发微晶玻璃玻纤石废品，其中基于UTi2O6的高耐久的褐铜矿陶瓷相包含长寿命的U和Pu，以及不太耐久的玻璃相以包含短寿命的裂变产物。这些陶瓷废品将使用谢菲尔德大学独特的放射材料热等静压(HIP)设备来制造。材料将通过X射线衍射、带X射线分析的电子显微镜、拉曼光谱、化学计量、热分析和U L3边缘X射线吸收光谱(与布鲁克海文国家实验室合作)进行表征。

This project seeks to address the requirement for treating damaged and degraded nuclear fuel materials present on the Sellafield site, immobilising these highly radioactive wastes in a glass-ceramic wasteform suitable for long term storage and final disposal. These materials range from wet sludges to dry granular materials. At present, there is no accepted waste treatment route or this material.We propose to develop a suite of novel glass-ceramic wasteforms for this purpose, based on synthetic brannerite, UTi2O6. The fuel residues are principally 96% UO2, with 3% fission products and 1% plutonium dissolved as a solid solution. It has been shown that geochemically altered natural mineral brannerites retain their uranium inventory for hundreds of millions of years, even after radiation induced amorphisation by alpha-decay. Natural brannerites have been shown to incorporate up to 4 wt% water, providing confidence that a synthetic brannerite wasteform will be compatible with processing of wet fuel residues. This project will design and develop develop glass-ceramic brannerite wasteforms, in which the highly durable brannerite ceramic phase, based on UTi2O6, incorporates long lived U and Pu, with a less durable glass phase to incorporate the short lived fission products.These ceramic wasteforms will be fabricated using the unique Hot Isostatic Pressing (HIP) facility for radiological materials, at the University of Sheffield. Materials will be characterised by X-ray diffraction, electron microscopy with X-ray analysis, Raman spectroscopy, pycnometry,thermal analysis, and U L3 edge X-ray Absorption Spectroscopy (collaboration with Brookhaven National Laboratory).