Understanding the Effect of Strain on Microstructure Properties and Environmental Degradation of AGR Fuel Cladding

了解应变对 AGR 燃料包壳微观结构性能和环境降解的影响

• 批准号: 2386762
• 金额: --
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2386762
• 关键词: Understanding; Effect; Strain; Microstructure; Properties

The backbone of the UK's nuclear energy is its fleet of Advanced Gas-cooled Reactors (AGR). The Uranium-oxide-based fuel within these reactors is safely encased in 20%Cr-25%Ni-Nb stainless steel cladding, to withstand the high operating temperatures and associated burn-up conditions. Radiation- and temperature-induced changes in cladding microstructure, however, occur during service exposure, which can render the material susceptible to localised corrosion, which has been observed during post-reactor storage. This PhD project aims to elucidate the effect of microstructure strain on the material performance and corrosion behaviour in post-reactor aqueous storage environment. The key objective of the research is to understand whether local microstructure strain and cold work plays a key role in AGR fuel pin failure, focusing primarily on aqueous storage conditions in pH-controlled environments.The microstructure of cold worked, strained, and sensitised (as well as sensitised and then strained) samples will be characterised using a wide range of characterisation techniques, including SEM, AFM/SKPFM, EBSD, XRD and XPS. Nano-, micro-, and meso-scale corrosion measurements using novel electrochemical characterisation techniques will be employed to probe the corrosion response. Corrosion rate measurements will then be correlated to local microstructure strain characteristics using in-situ time-lapse imaging and Digital Image Correlation (DIC). An extension of the work to investigate dry storage conditions using similar characterisation techniques and methodologies will also be explored via exposure of strained AGR cladding to thin layer electrolytes under Co-60 irradiation. The proposed project draws on a previous PhD study supported by NDA, which has explored general corrosion mechanism in sensitised simulants of AGR fuel cladding, identifying the role of carbide inclusions and associated corrosion mechanism. The proposed work here focuses on more realistic microstructure conditions relevant to AGR fuel pins, including end caps, strained anti-stacking grooves and welds.The student will have opportunity to spend several days @ NNL/Culham to discuss results/literature with NNL experts, and to Identify literature in NNL's data-base that may be of interest. A secondment into the Nuclear Decommissioning Authority (NDA) will be sought. (A Research visit to Swansea University to explore application of their in-situ time-lapse rigs.

英国核能的支柱是先进气冷反应堆（AGR）。这些反应堆内的铀氧化物燃料被安全地包裹在20%Cr-25%Ni-Nb的不锈钢包层中，以承受高温和相关的燃烧条件。然而，辐射和温度引起的包层微观结构变化发生在使用暴露期间，这可能使材料容易受到局部腐蚀，这在反应堆后储存期间已经观察到。本博士项目旨在阐明微观结构应变对反应器后水储存环境中材料性能和腐蚀行为的影响。研究的主要目的是了解局部微观结构应变和冷加工是否在AGR燃料销失效中起关键作用，主要关注ph控制环境下的水储存条件。冷加工，应变和敏化（以及敏化和应变）样品的微观结构将使用广泛的表征技术进行表征，包括SEM， AFM/SKPFM， EBSD， XRD和XPS。采用新型电化学表征技术的纳米、微观和中尺度腐蚀测量将被用于探测腐蚀响应。然后，腐蚀速率测量将使用现场延时成像和数字图像相关（DIC）与局部微观结构应变特征相关联。通过在Co-60照射下将应变AGR包层暴露于薄层电解质，还将探索使用类似表征技术和方法研究干储存条件的扩展工作。该项目借鉴了NDA之前支持的一项博士研究，该研究探索了AGR燃料包壳敏化模拟物的一般腐蚀机制，确定了碳化物夹杂物的作用和相关的腐蚀机制。这里提出的工作重点是与AGR燃料销相关的更现实的微观结构条件，包括端盖、应变反堆积槽和焊缝。学生将有机会花几天时间@ NNL/Culham，与NNL专家讨论结果/文献，并在NNL的数据库中识别可能感兴趣的文献。将寻求借调到核退役管理局（NDA）。(赴斯旺西大学进行研究访问，探索其现场延时钻机的应用。