基于热力学分析的核反应堆压力容器下封头完整性研究

doi:10.3901/JME.2025.02.141

摘要/Abstract

摘要： 反应堆严重事故工况下，堆芯由于不能得到足够的冷却温度急剧升高进而发生熔化。大量的熔融物重新定位到反应堆压力容器(Reactor pressure vessel, RPV)的下封头内部，可能导致下封头破裂和放射性释放。熔融物压力容器内滞留(In-vessel retention, IVR)是一种非常有效和关键的严重事故缓解措施。下封头作为IVR策略中主要部件，其在高温环境下的完整性研究对于IVR策略的成功实施具有重要意义。基于板壳理论力学分析，结合应力-应变本构关系，并采用多种失效判据对下封头完整性进行了进一步的热力学分析研究。通过对OLHF-1试验的数值模拟重点分析了压力容器下封头的完整性和热力学行为。结果表明，所开发的下封头力学模型能够较好地对下封头的力学失效行为作出判断，计算结果与试验数据符合较好。同时在高温环境下，下封头失效位置的壁厚由于蠕变迅速减小且应力出现突增。在此工况下下封头通常在应变最大处失效，失效时应变可达到20%以上。

关键词: 堆内熔融物滞留, 压力容器, 力学分析, OLHF-1试验

Abstract: Under severe accident conditions, the core will melt due to insufficient cooling, and a large amount of molten material will be relocated to the lower plenum of reactor pressure vessel(RPV), which may lead to lower head failure and radioactive release to the environment. In-vessel retention(IVR) is a very effective and critical mitigation measure for severe accidents. As the main component of IVR strategy, the integrity research of the lower head under high temperature environment is of great significance for the successful implementation of the IVR strategy. Based on the theoretical mechanical analysis of plates and shells, combined with the stress-strain constitutive relationship, and using a variety of failure criteria, the integrity of the lower head is further studied. Through the numerical simulation of OLHF-1 experiment, the integrity and thermodynamic behavior of the head under RPV were analyzed. The results show that the mechanical model of the lower head developed in this paper can better judge the mechanical failure behavior of the lower head, and the calculated results are in good agreement with the existing data. At the same time, in a high-temperature environment, the wall thickness at the failure location of the lower head rapidly decreases due to creep and the stress suddenly increases. Under this condition, the lower head typically fails at the location of maximum strain, with strains exceeding 20% upon failure.

Key words: in-vessel retention, RPV, mechanical analysis, OLHF-1 experiment

中图分类号:

TL35

杨皓, 高鹏程, 李济深, 翟润泽, 张斌. 基于热力学分析的核反应堆压力容器下封头完整性研究[J]. 机械工程学报, 2025, 61(2): 141-150.

YANG Hao, GAO Pengcheng, LI Jishen, ZHAI Runze, ZHANG Bin. Research on the Integrity of Lower Head of Reactor Pressure Vessel Based on Thermal-Mechanical Analysis[J]. Journal of Mechanical Engineering, 2025, 61(2): 141-150.

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