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Uranium Silicide/Uranium Diboride Composite Fuel Development

硅化铀/二硼化铀复合燃料开发

基本信息

批准号：
EP/T004983/1
负责人：
Joel Turner
金额：
$ 31.51万
依托单位：
University of Manchester
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FT004983%2F1
关键词：
Uranium Silicide Diboride Composite Fuel

项目摘要

Light Water Reactors (LWRs) comprise around 90% of the world's current nuclear generating capacity. The use of Accident Tolerant Fuels (ATFs) could offer significantly improved high temperature capability and operational safety. One way this can be achieved is by reducing the potential for reactivity with high temperature steam by replacing zirconium cladding with a ceramic composite material. This necessitates the replacement of existing UO2 fuel with a silcide; U3Si2, which is the focus of a concerted international research effort and aggressive commercial deployment plan \(see for example "Fuel of the Future", Nuclear Engineering International 2018). This research effort includes a national research programme within the United States, including large efforts at Idaho National Laboratory, Oak Ridge National Laboratory, The University of South Carolina, Westinghouse and General Atomics (amongst others). It includes a range of ATF concepts, some very close to current fuel designs (UO2, engineered to have a larger grain structure and coated claddings) as well as more research intensive efforts to deploy a true step-change (U3Si2 fuel pellets with composite silicon carbide cladding). International fuel vendors (Westinghouse, GE, Areva) are particuarly interested in devloping ATFs, as they may also provide the key to reducing nuclear capital cost by removing the need for currently expensive and multiply-redundant safety systems. The aim of this research is to establish if the introduction of a boride phase to U3Si2 could improve the materials high temperature water performance.This is a key challenge currently facing the ATF community Recent work performed by Sooby-Wood et al at Oak Ridge National Laboratory has demonstrated that U3Si2 rapidly and energetically pulverises when exposed to high temperature steam (E. Sooby Wood et al (2018). Journal of Nuclear Materials, 501, 404-412). Atomic scale modelling at the Universities of Bangor suggests that this is the result of a hydrogen reaction within the material, which leads to a rapid volume change and increases the surface area available for oxidation.Similar atomic modelling of the UB2 system performed at the University of Bangor (in support of the present work and currently being prepared for joint publication) suggests it will not be susceptible to this damage mechanism, and so could provide protection to U3Si2 while maintaining the benefits of an ATF fuel material (high thermal conductivity, high uranium density etc). Preliminary work has produced several test pellets by coarse mixing U3Si2 and UB2 powders in various weight percentages. On investigation, the boride and silicide phases do not have a detectable interaction layer around them, and the UB2 phase appears to have been successfully sintered within the U3Si2 phase. Preliminary steam tests on these pellets shows the steam reaction with composite pellets onsets at significantly higher temperatures than pure U3Si2 and appears to react much more slowly. This suggests that the presence of UB2 within U3Si2 may do more than simply limit the physical pathways by which U3Si2 is attacked by steam, as it appears to change the reaction mechanism in some way as noted by the lack of any reaction below 500C. The proposed work will build upon these preliminary studies and assess the feasibility of utilising UB2 within U3Si2 fuel material to improves its steam-corrosion resistance to acceptable levels. This will include pellet manufacture and characterisation, steam testing, proton irradiation tests, autoclave studies and characterisation of the effects of temperature cycles.

轻水反应堆（LWR）占世界目前核发电能力的90%左右。事故容忍燃料（ATF）的使用可以显着提高高温能力和操作安全性。实现这一点的一种方法是通过用陶瓷复合材料代替锆包层来降低与高温蒸汽反应的可能性。这就需要用硅化物取代现有的UO 2燃料; U3 Si 2，这是一项协调一致的国际研究工作和积极的商业部署计划的重点（例如，参见“未来的燃料”，核工程国际2018）。这项研究工作包括美国国内的一项国家研究方案，其中包括爱达荷州国家实验室、橡树岭国家实验室、南卡罗来纳州大学、西屋公司和通用原子公司（以及其他公司）的大量工作。它包括一系列ATF概念，其中一些非常接近当前的燃料设计（UO 2，设计成具有更大的晶粒结构和涂层包壳），以及更多的研究密集型努力，以部署真正的阶跃变化（U3 Si 2燃料芯块与复合碳化硅包壳）。国际燃料供应商（西屋电气、通用电气、阿海珐）对开发ATF特别感兴趣，因为它们还可以通过消除对目前昂贵和多重冗余安全系统的需求来提供降低核资本成本的关键。这项研究的目的是确定在U3 Si 2中引入硼化物相是否可以改善材料的高温水性能。这是ATF社区目前面临的一个关键挑战。橡树岭国家实验室的Sooby-Wood等人最近的工作表明，U3 Si 2在暴露于高温蒸汽（E. Sooby Wood et al（2018）. Journal of Nuclear Materials，501，404-412）。班戈尔大学的原子尺度模型表明，这是材料内部氢反应的结果，这导致快速的体积变化并增加了可用于氧化的表面积。（为了支持目前的工作，目前正在准备联合出版）表明，它不会受到这种损害机制的影响，因此可以为U3 Si 2提供保护，同时保持ATF燃料材料的优点（高导热性、高铀密度等）。初步工作已经通过将U3 Si 2和UB 2粉末以各种重量百分比粗混合而生产了几种测试芯块。在研究中，硼化物和硅化物相周围没有可检测的相互作用层，并且UB 2相似乎已经在U3 Si 2相中成功烧结。对这些芯块的初步蒸汽试验表明，与纯U3 Si 2相比，复合芯块的蒸汽反应在明显更高的温度下开始，并且反应似乎慢得多。这表明U3 Si 2中存在UB 2可能不仅仅是限制U3 Si 2被蒸汽攻击的物理途径，因为它似乎以某种方式改变了反应机制，如在500 ℃以下没有任何反应所指出的那样。拟议的工作将建立在这些初步研究的基础上，并评估在U3 Si 2燃料材料中利用UB 2的可行性，以将其耐蒸汽腐蚀性提高到可接受的水平。这将包括颗粒制造和表征、蒸汽试验、质子辐照试验、高压灭菌研究和温度循环影响的表征。