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

目前的先进气冷堆（AGR）核电站即将达到预期设计寿命，EDF能源公司正在寻求延长这些电站的寿命。然而，为了延长运行寿命并保持所需的安全要求，需要在反应堆内高温部件的评估中重新检查潜在的保守性。事实上，大量的AGR设备组件在500- 650 C的温度范围内的CO2环境中操作。然而，尽管几乎所有对相关材料（包括316 H型钢）进行的实验室机械试验都是在空气环境中进行的，但最近的研究结果表明，这些部件可能会受到CO2环境的不利影响，由于渗碳过程，CO2环境会增加钢的表面硬度，这也会降低这些材料的蠕变延展性。这些影响对EDF Energy及其合作伙伴开发的当前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.