Understanding the effect of stress on carburization and fracture of Type 316SS in simulated AGR gas coolant

目前先进气冷堆（AGR）核电站的设计寿命已经接近尾声，法国电力公司正在寻求延长这些电站的使用寿命。然而，为了延长使用寿命并维持所需的安全要求，需要对反应堆内高温组件评估中的潜在保守性进行重新检查。事实上，相当数量的AGR装置组件在500-650℃范围内的二氧化碳环境中运行。然而，尽管几乎所有对相关材料（包括316H型钢）进行的实验室机械测试都是在空气环境中进行的，但最近的研究结果表明，这些成分可能会受到二氧化碳环境的不利影响，二氧化碳环境会增加钢的表面硬度，因为渗碳过程也会降低这些材料的蠕变延展性。这些影响对目前由EDF能源公司及其合作伙伴开发的高温结构完整性评估程序R5提出了挑战。

The current Advanced Gas-cooled Reactors (AGR) nuclear plants are reaching the end of the intended design life and EDF Energy is seeking to extend the lifetime of these stations. However, to enable an extension to the operational life and maintain the required safety requirements re-examination of potential conservatisms within assessments of in-reactor high temperature components is required. In fact, a significant number of AGR plant components operate in a CO2 environment at temperatures in the range 500-650C. However, whist virtually all of the laboratory mechanical tests carried out on relevant materials (including Type 316H steel) have been performed in an air environment, there are recent findings that suggest that these components may be adversely affected by the CO2 environment which increases the surface hardness of the steels due to a carburization process which also decreases the creep ductility of these materials. These implications challenge the current high temperature structural integrity assessment procedure R5, developed by EDF Energy and its partners.