Delayed hydride cracking of zirconium alloys

延迟氢化物开裂（DHC）是氢作为脆性氢化物析出导致金属开裂的一种失效机制。这对于用作核反应堆压力边界和放射性边界的锆合金来说是一个特殊的问题。当这些边界失效时，无论是在运行期间还是在乏燃料长期储存期间，都会对运行中的核反应堆和核燃料造成严重后果。目前，锆合金的安全操作是通过在有限数量的实验条件下根据经验数据对操作条件进行限制来保证的。多年来发展了DHC模型，希望能够在比实验测量范围更广的条件下预测DHC。在过去的五年中，用于解释80年代和90年代发展的DHC速率的模型受到了严厉的质疑，最近申请人等人已经表明，现有的预测DHC速度的模型是基于错误的概念和错误的假设。此外，申请人等人还引入了一种新的DHC速度模型，该模型已成功用于预测广泛的实验结果；这是前所未有的，令人兴奋的，并且结合了对基础物理的更好理解。本提案的目标是在进一步测试和开发这种新的DHC速度预测模型的同时加深这种理解。一个可靠的、健壮的DHC物理模型将有助于更好地预测锆组件的失效，从而提高核反应堆运行和长期储存乏核燃料的安全性。

Delayed hydride cracking (DHC) is a failure mechanism of certain metals in which hydrogen precipitating as brittle hydride leads to cracking of the metal. This is a particular problem for zirconium alloys that are used as pressure boundaries and radioactivity boundaries in nuclear reactors. When failure of these boundaries occurs there are severe consequences for an operating nuclear reactor and also for the nuclear fuel, both during operation and later when the spent fuel is in long-term storage. Currently, safe operation with zirconium alloys is ensured by placing limits on operating conditions based on empirical data for a limited number of experimental conditions. Models of DHC were developed over the years with the hope of enabling predictions of DHC under a wider range of conditions than can be experimentally measured. In the last five years the models used to explain the rates of DHC developed in the 80s and 90s have been critically questioned, and very recently the applicant et al. have shown that existing models to predict DHC velocity are based on faulty concepts and wrong assumptions. In addition, the applicant et al. have introduced a new model for DHC velocity that has successfully been used to predict a broad spectrum of experimental results; this is unprecedented and exciting, and incorporates a better understanding of the underlying physics. The goal of this proposal is to deepen this understanding while testing and developing further this new predictive model of DHC velocity. A reliable robust physical model of DHC will lead to better predictions of failures of zirconium components and, thus, improved safety for operating nuclear reactors and spent nuclear fuel in long-term storage.