秦山CANDU-6重水反应堆锆合金压力管的老化形式与缓解措施

Degradation of Zirconium Alloy Pressure Tube in Qinshan CANDU-6 Heavy Water Reactor and Its Mitigation

CANDU-6重水反应堆堆芯压力管采用的锆合金(Zr-2.5Nb)材料长期处于高温、高压、高辐照的运行环境。由于锆合金吸氘,压力管存在氢致延迟开裂的风险。秦山第三核电厂通过改进制造和安装工艺、加强对运行工况的控制以及开展定期检查和预防性维修,改善压力管的径向蠕变状况,降低残余应力,减少氢致延迟开裂的风险,并及时跟踪压力管的降级程度,为电厂寿期管理提供重要信息和依据。

Pressure tubes are critical components in heavy water reactors,and its ageing and degradation directly has effect on the service life of the reactor.The material of the pressure tube of Qinshan Phase Ⅲ CANDU-6 reactors are zirconium alloy （Zr-2.5Nb）,and the dimensions and mechanical properties of pressure tubes change under long-time service conditions of high temperature,high pressure,and high radiation.Also there is risk that delayed hydride cracking （DHC） may happen on pressure tubes due to the pickup of deuterium by zirconium alloy.To improve the radial creep rates of pressure tubes,reduce the residual stress and risk of DHC,and follow up the degradation extent of pressure tubes to provide important information and evidences for life assessment,Qinshan Phase Ⅲ implemented the improvements of manufacture and installation process,control of service chemical conditions and periodic inspections,and will implement preventative maintenance.