熔融物堆内滞留条件下RPV长期结构完整性分析

Long-term Structural Integrity Analysis for Reactor Pressure Vesselunder In-vessel Retention Condition

熔融物反应堆压力容器(RPV)内滞留(IVR)是三代核电厂重要的严重事故缓解措施,而防止RPV的热工失效和结构失效是实现IVR的前提。本文建立考虑内壁面熔蚀的RPV有限元模型,在温度场分析的基础上,开展蠕变计算,得到不同时刻下的应力应变响应,通过选取典型评定路径并利用基于Larson-Miller参数的累积损伤理论进行蠕变损伤计算及评价。分析结果表明:在考虑一定内压的IVR条件下,RPV不会发生蠕变断裂,长期结构完整性可保证。本文的研究方法可为后续核电厂RPV在IVR条件下的结构完整性分析提供参考。

In-vessel retention(IVR)is one of appropriate severe accident mitigation strategies for generationⅢnuclear power plant(NPP),and assurance of prevention against to thermal failure and structural failure of reactor pressure vessels(RPV)is the prerequisite of IVR.In the paper,the finite element model of RPV considering the lower head melting was established,the creep calculation was carried out after the temperature field analysis,and the stress-strain responses for different time were obtained.By means of choosing representative evaluation sections and applying the accumulative damage theory based on Larson-Miller parameter,the creep damage calculation and evaluation were conducted.The results show that the failure modes of creep rupture will not happen for RPV under IVR condition when a certain amount of internal pressure exist,and the long-term structural integrity can be ensured.The approach employed in this paper can be utilized in structural integrity evaluation of RPV under IVR for other new type NPPs.