Fast efficient modelling of hydride reorientation

对氢扩散和氢化物沉淀机理的理解是锆合金核燃料包壳延迟氢化物开裂（DHC）预测的基础。核废料储存库中核燃料销的使用寿命和销的完整性存在问题。这个项目建立在一个以前的学生的研究基础上，使用分析应力场，结合离散位错，以毫米尺度的面积建模，但精度为一微米，包括晶粒取向效应，但在几秒钟而不是几小时内（根据最先进的相场模型）。罗尔斯·罗伊斯公司正在研究将这种新的建模方法纳入他们的研究战略，并通过能源部（DOE）和电力研究所（EPRI）在美国引起了极大的兴趣。虽然显示出潜力，但该模型只捕获了一些相关现象。该项目将结合现有框架，DHC的其他关键方面，包括晶界相容性应力，晶间与晶间氢化物沉淀；进一步加强原子氢扩散与微尺度氢化物沉淀的耦合（使冷却效应能够建模，特别是称为棘轮的热循环），并最终开发可视化/图像分析工具，以表征氢化物重新定向的所得微观结构，从而产生可用于工业的概率模型。

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.