Hydrogen embrittlement in fuel cladding in advanced candu and generation IV reactors

加拿大签署《京都议定书》和《悉尼协议》，将需要作出相当大的努力来限制温室气体排放，从而依赖清洁能源。核能被认为是未来的清洁能源，新型先进CANDU反应堆具有更高的燃料燃耗、更高的效率和优良的运行安全性。此外，加拿大正在设计第四代反应堆，也考虑为生产清洁燃料氢提供热量。这些先进反应堆的性能和高效率与更高的工作温度有关，必须作出重大努力来提高材料在高温环境中的性能和预期寿命。本方案旨在评估微观结构在燃料包壳氢脆中的作用，以提高燃料包壳管在更高工作温度下的预期寿命。提出的研究目标是改进先进CANDU反应堆中使用的锆合金-4包层的工艺和结构，并为未来在第四代反应堆中的应用提供新型合金E110 （Zr-1Nb）。新的取向成像实验技术，尚未应用于包层脆化研究，将使我们第一次研究晶界结构在氢化物形成中的作用，并引入微观织构和晶界工程的概念，提出改善氢脆化的方法。在此基础上，将建立新的氢化物脆化计算机模型，以模拟不同Zr合金的微观组织。模拟结果将允许定义最佳微观结构，并可用于下一阶段的研究，以创新位于安大略省Arnprior的通用日立工厂的燃料颗粒制造工艺。

The signing of the Kyoto protocol and Sydney agreement by Canada will require considerable efforts to limit green house gas emission and therefore to rely on clean energy. Nuclear energy is considered, a clean energy of the future and new advanced CANDU reactors offer higher fuel burn-up, higher efficiency and excellent safety of operation. In addition Canada is engaged in design of the Generation IV reactors that are also considered for providing heat for production of clean fuel, hydrogen. Performance and high efficiency of these advanced reactors is linked to higher operating temperature and significant efforts have to be made to improve the performance and life expectancy of materials in high temperature environment. The present proposal is aiming to evaluate a role of microstructure in the hydrogen embrittlement of fuel cladding in order to improve life expectancy of fuel cladding tubes at higher operating temperatures. The proposed research targets improvement of processing and structure of Zircaloy-4 cladding to be used in advanced CANDU reactors and novel alloy, E110 (Zr-1Nb) for future application in the reactors of the IV generation. Novel experimental technique of orientation imaging, that was not yet applied in cladding embrittlement research, will allow us for the first time to examine a role of structure of grain boundaries in hydride formation and to introduce concepts of microtexture and grain boundary engineering to propose methods for improving hydrogen embrittlement. Based on the results obtained novel microstructural computer model of hydride embrittlement will be developed that will allow to simulate the process for different Zr alloys microstructures. The result of simulation will allow to define optimum microstructure and can be used in the next stage of research to innovate process of manufacturing fuel pellets in G.E-Hitachi plant in Arnprior (Ontario)