Ceramic Coatings for Clad (The C^3 Project): Advanced Accident-Tolerant Ceramic Coatings for Zr-alloy Cladding

加强核燃料安全是核电继续使用和发展的重要组成部分。可以加强安全性的一个领域是加强核燃料周围的包层。这种涂层将进一步提高燃料在正常反应堆运行下的长期稳定性，同时在类似福岛事故发生时提供额外的保险。这些新的涂层将在锆合金包层和空气/水之间提供一个屏障，这将有助于防止在冷却剂丢失事故（LOCA）时形成的蒸汽形成氢气，即2011年3月发生在福岛第一核电站的过程。利用英国和美国的专业知识，一个合作研究团队已经联合起来开发这种涂料。将解决两种选择，一种是基于使用氧化物，如氧化锆，而另一种是基于三元碳化物/氮化物基材料，如MAX相。M(n+1)AX(n)相不仅可以从辐射损伤中迅速恢复，而且具有优异的热/腐蚀性能，使其成为这种应用的理想选择。为了开发用于当前和未来核反应堆机群的新涂层，必须制备新涂层，并在一系列反应堆条件下检查其稳定性。实验计划将解决诸如涂层的制备、涂层与燃料之间结合的稳定性、辐射损伤对界面的影响，以及增强涂层如何提高燃料在裂变堆芯内高温/高压下的稳定性等问题。这些实验也将用于验证腐蚀模拟，提供一种可靠的模拟方法。测试后对涂层的最后评估是它们在模拟LOCA事件的条件下的表现。这项工作的结果将用于开发现有和未来反应堆技术的技术。

Enhancing the safety of nuclear fuel is an important component in the continued use, and expansion, of nuclear power. One area where safety can be enhanced is enhancing the cladding around the nuclear fuel. Such a coating will enhance further the long term stability of the fuel under normal reactor operation, whilst at the same provide an extra level of insurance should an incident similar to that in Fukushima happen. These new coatings will provide a barrier between the Zircalloy cladding and air/water, which will help to prevent the formation of hydrogen gas from steam formed when there is a loss of coolant accident (LOCA), i.e. the process that happened at Fukushima Daichi, in March 2011.Using the combined expertise/knowledge from within the UK and US a collaborative research team has been put together to develop such coatings. Two options will be addressed one based on using oxide, such as zirconia, whilst a second will be based on ternary carbide/nitride based materials, such as MAX phases. M(n+1)AX(n) phases have previously been shown to not only recover rapidly from radiation damage, but also excellent thermal/corrosion properties making them ideal for this application. For the development of new coatings to be used in the current, and future, nuclear reactor fleet, new coatings must be prepared, and examined for stability, under a range of reactor conditions. The experimental programme will address issues such as the preparation of the coating, stability of bonding between coating and fuel, the effects of radiation damage on the interface, and how the enhanced coating increases stability of the fuel to both high temperatures/pressures experienced within a fission core. These experiments will also be used to validate simulations of corrosion, providing a means by which simulations can be reliably used. One final assessment of the coatings once tested, is how they behave under conditions that model a LOCA event. The results from this work will be used in developing technologies for existing and future reactor technologies.