Global Bending Response Analysis of Elastic and Viscoplastic Nuclear Shipping Cask Structures Subjected to Impact Loading

Within the framework of lumped mass upgraded beam theory in which rotatory and elastic shear deformation effects are considered, the title analysis is made for the case of large realistic lead-shielded, cylindrical stainless steel shipping casks equipped with end impact limiters. A computerized study developed elsewhere for the dynamic response analysis of elastic and elastic/viscoplastic beams and frames is first extended to include shear deformation and rotatory inertia effects and subsequently used in the cask impact response analysis study. Three types of impact limiter reaction force pulses are considered and three simplified analysis techniques (i.e., quasi-static, dynamic amplification factor and elementary beam analysis techniques) used in shipping cask design are evaluated. In particular, effects of shear deformation and rotatory inertia on impact responses and strain rate sensitivity effects on inelastic dynamic cask response behavior are studied. Appropriate guidelines are formulated for: 1) general use of these techniques in impact design analysis, and 2) treating strain rate sensitivity effects on material strength properties in conjunction with use of elastic, limit and elastic-plastic design analysis methods.