IVR中熔融堆芯被牺牲性材料稀释后的RPV弹塑性有限元分析

布置氧化物牺牲性材料（OSM）的熔融堆芯稀释方案是一种较有前途的容器内滞留（IVR）增强技术。布置OSM后，堆芯熔融物的质量和体积增大，且熔池结构发生翻转，氧化物层位于反应堆压力容器（RPV）直筒段，因此分析布置OSM后RPV的结构完整性是评价稀释方案可行性的重要研究内容。本文分别对未布置OSM（传统IVR）和布置OSM后的RPV进行弹塑性分析。研究发现，RPV结构不连续区域是结构中最薄弱的位置，未布置OSM时，结构不连续部位进入极限承载状态，但此处外壁面的最大纵向主应变较小（约3.9%），RPV不会发生塑性撕裂失效；布置OSM后，RPV的结构承载能力显著增强，在远离结构不连续区域的部位，壁面非屈服区厚度增大，即使在结构不连续部位，壁面也未进入极限承载状态，且也不会发生塑性撕裂失效。

Elastic-plastic Finite Element Analysis of RPV during IVRwith Core Melt Diluted by Sacrificial Material

Diluting the core melt with oxide sacrificial material(OSM)during in-vessel retention(IVR)is a promising severe-accident-management strategy of advanced LWRs.When the relocated core melt is diluted by OSM,the mass and volume of the core melt mixture increase and the oxide layer locates in the cylindrical portion of RPV due to the inverse stratification of melt pool configuration.Therefore,researches on the structural integrity are essential to evaluate the effectiveness of the strategy.In this paper,elastic-plastic finite element analyses of RPV during IVR with and without OSM were investigated.The results show that structural failure prefers to occur in the discontinuous part of RPV.The discontinuous part reaches ultimate limit state during IVR without OSM.However,the local maximum principle strains in the direction along the wall meridian(longitudinal bending)are about 3.9％,indicating margins to tearing.When OSM is used during IVR,a core of strong(below yield)material appears everywhere,which means that the ultimate limit state does not appear even in the discontinuous zone.Moreover,the thickness of the core material below yield becomes larger in the positions far away from the discontinuous part.Tearing will also not happen in the discontinuous zone.Therefore,the RPV can suffer enhanced load during IVR with OSM.