华龙一号反应堆压力容器下封头高温蠕变研究

Study on High-temperature Creep for Lower Head of HPR1000 Reactor Pressure Vessel

高温蠕变是华龙一号(HPR1000)反应堆压力容器(RPV)下封头在严重事故工况下的主要失效模式。为准确地研究采用国产16MND5锻件制造的HPR1000 RPV下封头的高温蠕变问题,确保RPV下封头在严重事故工况下的结构完整性,基于试验获得的材料高温蠕变数据,联合数值模拟和理论分析,对HPR1000 RPV下封头高温蠕变问题进行了系统的研究。首先建立了RPV下封头材料高温蠕变本构模型。利用ANSYS软件开展了高温及内压载荷作用下的下封头高温蠕变数值模拟研究,获得了下封头蠕变应变和蠕变应力分布。此外,首次针对RPV下封头高温蠕变问题进行了理论研究。结果表明,RPV下封头高温蠕变主要发生在温度高于450℃的区域;在严重事故工况下,HPR1000 RPV下封头不会发生高温蠕变失效;内压增大将导致RPV塑性失效范围扩大;RPV下封头稳态蠕变理论分析结果与数值模拟结果相吻合,理论分析结果揭示了RPV下封头分层失效现象。

High-temperature creep is main failure mode of HPR1000 RPV lower dome under severe accident.To accurately study high-temperature creep of HPR1000 RPV lower dome made of domestic 16MND5 forging and assure structure integrity of RPV lower dome under severe accident,high-temperature creep of HPR1000 RPV lower dome is studied systematically in this paper by combining numerical simulation and theoretical analysis based on the high-temperature creep test data.Firstly,the constitutive model of RPV lower dome material is established.Adopting ANSYS software,the numerical simulation of the high-temperature creep of the lower dome under the action of high temperature and internal pressure is performed,and creep strain and stress distributions for lower dome are obtained.Furthermore,the high-temperature creep problem of RPV lower dome is theoretically studied for the first time.The research results indicate,high-temperature creep of RPV lower dome mainly occurs in the zone whose temperature is higher than 450℃;Under severe accident,HPR1000 RPV doesn’t fail due to high-temperature creep;Plasticity failure zone will enlarge with the increase of internal pressure;The theoretical analysis results of steady creep are consistent with the numerical simulation ones,and deeply reveal the layered failure phenomenon of RPV lower dome.