Hydrogen ingress through the rolled joints of CANDU pressure tubes

莱克能源产品有限公司和卡尔顿大学正在合作开发实验和模型，模拟氢气通过用于将端部配件连接到CANDU燃料通道压力管的轧制接头的运动。压力管中的氢会导致一种与时间相关的断裂机制，称为延迟氢化物开裂（DHC），这是核反应堆和化工厂中锆部件多次失效的原因。在CANDU反应堆中，氢气水平通过设计保持较低，然而，在操作期间，氢气进入每个压力管末端的轧制接头。监控活动和具有较大安全裕度的预测模型用于保证压力管中的氢水平远低于DHC可能发生的水平。目前采用的余量反映了我们对轧制接头侵入机制的理解水平。可以说，通过更好的理解，这些利润可以安全地减少，并通过过早更换良好的压力管节省数百万美元的成本。莱克能源产品有限公司是仅有的两家CANDU反应堆轧制接头端部配件供应商之一。他们希望与卡尔顿大学合作，以了解滚动接头入口机制，并最终开发出更好的端部接头设计。

Laker Energy Products Ltd and Carleton University are collaborating to develop experiments and models that simulate hydrogen movement through the rolled joints used to couple end fittings to pressure tubes in CANDU fuel channels. Hydrogen in pressure tubes can lead to a time-dependent mechanism of fracture called delayed hydride cracking (DHC) that has been responsible for several failures of zirconium components in nuclear reactors and chemical plants. In CANDU reactors, hydrogen levels are kept low by design, however, during operation hydrogen ingress happens across the rolled joints at the end of each pressure tube. Surveillance campaigns and predictive models with large safety margins are used to guarantee hydrogen levels in the pressure tubes stay well below the levels where DHC can occur. Margins are currently employed that reflect our level of understanding of the mechanism of ingress across the rolled joints. Arguably these margins could be safely reduced with better understanding, and save millions of dollars of avoided costs by prematurely replacing good pressure tubes. Laker Energy Products Ltd is one of only two suppliers of end fittings for rolled joints in CANDU reactors. They wish to collaborate with Carleton University to understand the rolled-joint ingress mechanism and ultimately to develop a better end-fitting design.