Fast efficient modelling of hydride reorientation

对氢扩散和氢化物析出的机理的理解是预测锆合金核燃料包壳延迟氢化物开裂的基础。DHC给核燃料销的使用寿命和废物储存中销的完整性带来了问题。这个项目建立在前一个学生的研究基础上，该研究使用分析应力场与离散位错相结合来模拟毫米尺度的面积，但具有一微米的精度，包括颗粒取向效应，但需要几秒钟而不是几小时(根据最先进的相场模型)。劳斯莱斯正在研究新的建模方法，将其纳入他们的研究战略，并通过能源部(DOE)和电力研究所(EPRI)在美国获得了极大的兴趣。虽然该模型显示出潜力，但只捕捉到了一些相关现象。这一项目将与现有框架、DHC的其他关键方面相结合，包括晶界相容应力、晶间氢化物沉淀与跨晶态氢化物沉淀；进一步加强原子氢扩散与微尺度氢化物沉淀的耦合(以便能够模拟冷却效应，特别是称为棘轮的热循环)，最后开发可视化/图像分析工具，以表征氢化物重新定向所产生的微观结构，从而产生可供工业使用的概率模型。

A mechanistic understanding of hydrogen diffusion and hydride precipitation underpins the prediction of delayed hydride cracking (DHC) in zirconium alloy nuclear fuel cladding. DHC presents a problem to service life of nuclear fuel pins and integrity of pins in waste storage. This project builds upon a study by a previous student to use analytical stress fields, in combination with discrete dislocations, to model a millimetre scale area but with single micron accuracy, including grain orientation effects, but in seconds rather than hours (as per state-of-the-art phase field models). The new modelling approach is being examined by Rolls-Royce for incorporation into their research strategy and has gained significant interest in the US via the Department of Energy (DOE) and Electric Power Research Institute (EPRI). Whilst showing potential, the model captures only some of the relevant phenomena. This project, will couple to the existing framework, other crucial aspects of DHC, including grain boundary compatibility stresses, intergranular versus transgranular hydride precipitation; further enhancement of the coupling of atomic hydrogen diffusion to microscale hydride precipitation (to enable cooling effects to be modelled, especially thermal cycles known as ratchetting) and finally to develop visualization/image analysis tools to characterize the resultant microstructures for reorientation of hydrides producing a probabilistic model that can be used by industry.