Delayed hydride cracking of zirconium alloys

延迟氢化物开裂（DHC）是某些金属的失效机制，其中氢作为脆性氢化物沉淀导致金属开裂。 这对于在核反应堆中用作压力边界和放射性边界的锆合金是一个特别的问题。 当这些边界发生故障时，在运行期间和之后当乏燃料处于长期储存中时，对运行的核反应堆以及对核燃料都存在严重后果。 目前，通过基于有限数量的实验条件的经验数据对操作条件设置限制来确保锆合金的安全操作。 DHC的模型是多年来开发的，希望能够在比实验测量更广泛的条件下预测DHC。 在过去的五年中，用于解释80年代和90年代开发的DHC速率的模型受到了严格的质疑，最近申请人等人已经表明，预测DHC速率的现有模型是基于错误的概念和错误的假设。 此外，申请人等人已经引入了DHC速度的新模型，该模型已经成功地用于预测广泛的实验结果;这是前所未有的和令人兴奋的，并且结合了对基础物理学的更好理解。 本提案的目标是加深这种理解，同时进一步测试和开发这种新的DHC速度预测模型。 一个可靠的DHC物理模型将导致更好地预测锆部件的故障，从而提高核反应堆和乏核燃料长期储存的运行安全性。

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.