When damaged core materials are relocated to the reactor lower head with penetrations during a severe accident, the loss integrity of the reactor pressure vessel caused by ejection of a penetration tube will occur earlier than the global failure of the reactor lower head. The overall aim of this study is to review and improve the previous contact pressure evaluation models. In this part of the study, it was shown that the previous model in the elastic region only considers the deformation of a penetration tube itself by assuming one hollow cylinder with a limited stress-strain condition. Therefore, the new expression of the contact pressure at the interface was derived by stress analysis with assumption of additional concentric outer cylinder for a reactor lower head. The new contact pressure model was validated using finite element analysis.

当发生严重事故时，损坏的堆芯材料被重新安置到带有贯穿件的反应堆下封头时，由贯穿管弹射引起的反应堆压力容器的完整性损失将比反应堆下封头的整体故障发生得更早。本研究的总体目标是回顾和改进以前的接触压力评估模型。在这部分研究中，表明弹性区域中的先前模型仅通过假设一个具有有限应力应变条件的空心圆柱体来考虑穿透管本身的变形。因此，界面处接触压力的新表达式是通过应力分析推导出来的，假设反应堆下封头有额外的同心外圆柱体。使用有限元分析验证了新的接触压力模型。