Dynamic Analysis and Evaluation of Control Rod Device Mechanism Missile Impact on Shielding Plate

The flying of missile will severely jeopardize the structural integrity in control rod ejection accident. In order to analyze the strength of a new type of shielding plate under control rod drive mechanism (CRDM) missile impact, this article develops the simulation model and conducts the response analysis of the missile under 4 cases. In addition, the strain analysis and evaluation of protection shielding plate at the most dangerous case are performed. The motion analysis of CRDM missile indicates that the fracture at trapezoid thread place as well as the shielding plate rim under impact is most dangerous because the maximum kinetic energy of the impact can be obtained. So only this case should be examined when performing the evaluation of the shielding plate. Stress analysis shows the maximum stress intensity of the shielding plate will exceed the yielding stress and thereby local plasticity will occur. Strain analysis shows that compared with the extension ratio at structural failure, the computed strain still has margin to ensure the shielding plate will not be penetrated. Meanwhile the strain analysis of bolts which fix shielding plate are calculated. The strain level of two bolts are exceed limit and others is relatively low. The shield plate can be firmly fixed. Hence, this new type of the protection shielding plate is capable to prevent the damage of other components by the flying of CRDM missile.