压水堆核电厂一回路主管道在线断裂评价技术精度验证

Study on Accuracy Verification of On-line Fracture Evaluation for Primary Loop Pipeline of PWR Nuclear Power Plant

压水堆核电站一回路主管道是核安全一级部件,其长寿期服役安全性能是影响核电站寿命的一个关键因素。由于一回路主管道尺寸大、制造等级高,现有的实验研究数据多是考虑内压、弯曲等单一机械载荷,尚未考虑载荷组合和热瞬态的复杂载荷,工程评价中仍需基于有限元(FE)的数值仿真方法。在大型FE软件基础上开发获得一款基于瞬态监测的在线断裂评价软件,通过与日本核能安全组织安全标准委员会公开的一回路主管道实验数据进行对比,验证所开发软件算法的适用性。分析结果表明,基于FE数值仿真方法预测的管道载荷-位移数据与实验数据最大偏差为8.2%;由于断裂时裂纹前沿明显变形,基于FE计算的断裂参量与实验偏差较大(极限条件时偏差达到30%左右);但在综合考虑管道塑性垮塌失效模式的影响后,可将与实验结果的偏差降低至6.8%。综上所述,认为所开发软件中的FE算法是可靠的,能够满足工程评价的技术需求。

The primary loop pipeline acts as the PWR nuclear power plant’s Class I component in the nuclear safety.The long-term safe performance becomes a key factor affecting the service life of the nuclear power plant.Considering the fact that the large-size primary loop pipeline there asks for high manufacturing level,and the existing experimental data mostly consider the single mechanical load such as internal pressure or bending only and neglect the complex load combination and thermal transient load,this makes the finite element(FE)-based numerical simulation method become needed in engineering evaluation.In this paper,the on-line fracture evaluation software based on transient monitoring was developed and compared with the primary loop pipeline’s experimental data published by the safety standards committee of Japan nuclear safety organization,verifying the applicability of this software algorithm shows that,the maximum deviation between the pipeline load displacement data predicted based on FE numerical simulation method and the experimental data is 8.2%.Due to the obvious deformation of the crack front during fracture,the fracture parameters calculated based on FE have a large deviation from the experiment(the deviation reaches about 30%under the limit condition).However,after comprehensively considering the failure mode’s influence of the pipeline plastic collapse,the deviation from the experimental results can be reduced to 6.8%.In conclusion,the FE algorithm in the software developed is reliable and it can meet technical requirements of the engineering evaluation.