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The Development of Advanced Technologies and Modelling Capabilities to Improve the Safety and Performance of Nuclear Fuel

开发先进技术和建模能力以提高核燃料的安全性和性能

基本信息

批准号：
EP/I003320/1
负责人：
Timothy Abram
金额：
$ 148.35万
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：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FI003320%2F1
关键词：
Development Advanced Technologies Modelling Capabilities

项目摘要

The main factors that limit the performance of nuclear fuels are related to cladding failure due to interactions with the fuel pellet and reactor coolant. Improvements to our understanding of the cladding failure mechanisms will enhance our ability to predict their effects, leading both to improvements in the safety and operation of current fuels, and to technological developments that will produce improved fuel, cladding, and coating materials. The research tasks below seek to address each of these issues in turn, from the perspective of both current and advanced fuel designs.Aomistic modelling research will focus on the input that atomic scale simulations make in describing the behaviour of micro-structural defects. This will refine our understanding of the fundamental physical processes that degrade fuel performance, and will result in improvements to current semi-empirical fuel performance models. The simulations will focus upon the interaction of fission products, radiation damage and dislocations, processes responsible for macroscopic observables such as fission gas release and irradiation induced creep.Fuel and cladding dimensional changes resulting from thermo-mechanical and irradiation conditions produce complex pellet-clad mechanical interactions (PCMI) that are known to cause fuel failure, especially under accident conditions. Models for PCMI failure based on ramp-test data have been developed, but these are highly empirical and therefore of limited applicability. However, advances in finite element (FE) modelling now permit the development of detailed models, and techniques such as the extended FE method can be applied to model crack growth and crack tip stresses and strains accurately whilst taking into account residual and applied stress redistribution. This research will investigate the development of pellet crack patterns and pellet-clad interface stresses under both normal and off-normal conditions. Mechanistic models for pellet failure and cladding damage will be developed.Research into composite cladding will investigate the potential for silicon carbide composites to provide significantly better performance compared with existing cladding materials. A new approach will be investigated, based on a solid SiC inner tube wrapped with SiC fibers and bonded using SiC vapour infiltration. The research will address fundamental aspects of this new concept, including: characterisation of the relationship between both design and manufacturing parameters and mechanical strength; ability of the tube to remain impermeable against fission products; and resistance to oxidation and fission product attack at high temperatures. Although UO2 has been used for many years as a fuel material, promising new materials have ben developed that could offer advantages in terms of safety and performance. The objective of this research is to identify alternative fuel materials and fuel forms; to evaluate their physical properties such as thermal conductivity; assess their reactivity with water using autoclave testing; and to assess industrially-feasible manufacturing routes. Candidate materials include alloys such as U3Si2, U-Mo, U-Zr and covalent compounds such as carbides and nitrides (in the latter case with additives to reduce the reaction rate in water). TRISO coated fuel particles manufactured by chemical vapour deposition (CVD) have demonstrated remarkable performance, but are known to be susceptible to attack by fission products such as Pa. This research will provide a fundamental understanding of these issues and will investigate alternative materials and processes to provide improved performance. The high temperature mechanical properties of coatings will be examined to understand the effects of manufacturing conditions. The mechanisms of fission product transport will be studied with a view to introducing materials and microstructural changes that will improve performance in this respect.

限制核燃料性能的主要因素与燃料球团和反应堆冷却剂相互作用导致的包层失效有关。提高我们对包层失效机制的理解将提高我们预测其影响的能力，从而提高当前燃料的安全性和操作，并促进技术发展，从而生产出改进的燃料、包层和涂层材料。下面的研究任务依次从当前和先进燃料设计的角度来解决这些问题。原子模型研究将集中于原子尺度模拟在描述微观结构缺陷行为方面所做的输入。这将改进我们对降低燃料性能的基本物理过程的理解，并将改进目前的半经验燃料性能模型。模拟将集中在裂变产物的相互作用，辐射损伤和位错，负责宏观观察的过程，如裂变气体释放和辐射诱发蠕变。由于热机械和辐照条件导致的燃料和包层尺寸变化会产生复杂的颗粒包层机械相互作用（PCMI），这是导致燃料失效的已知原因，特别是在事故条件下。基于斜坡试验数据的PCMI失效模型已经开发出来，但这些模型是高度经验性的，因此适用性有限。然而，有限元（FE）建模的进步现在允许开发详细的模型，并且诸如扩展有限元方法之类的技术可以应用于精确地模拟裂纹扩展和裂纹尖端应力和应变，同时考虑残余应力和外加应力重分布。本研究将探讨正常和非正常条件下球团裂纹模式和球团包层界面应力的发展。将开发球团破坏和包层损伤的力学模型。对复合包层的研究将研究碳化硅复合材料的潜力，以提供比现有包层材料更好的性能。我们将研究一种新的方法，即在固体碳化硅内管内包裹碳化硅纤维，并用碳化硅蒸汽渗透进行粘合。该研究将解决这一新概念的基本方面，包括：设计和制造参数与机械强度之间关系的表征；管对裂变产物保持不渗透的能力；并在高温下抵抗氧化和裂变产物的攻击。虽然UO2作为燃料材料已经使用多年，但在安全性和性能方面具有优势的新材料已经被开发出来。这项研究的目的是确定替代燃料材料和燃料形式；评估其物理性质，如导热性；使用高压灭菌器测试评估其与水的反应性；并评估工业上可行的制造路线。候选材料包括合金，如U3Si2， U-Mo， U-Zr和共价化合物，如碳化物和氮化物（在后一种情况下，添加添加剂以降低在水中的反应速率）。由化学气相沉积（CVD）制造的三iso包覆燃料颗粒已经证明了卓越的性能，但已知容易受到裂变产物（如Pa）的攻击。这项研究将提供对这些问题的基本理解，并将研究替代材料和工艺，以提供更好的性能。涂层的高温力学性能将被检查，以了解制造条件的影响。将研究裂变产物输运的机制，以期引入材料和微观结构变化，从而提高这方面的性能。