Publications Details
Structural analysis of the source term transportation cask
Structural calculations were performed to evaluate the source-term nuclear fuels transport cask (ST Cask) under various hypothetical accident scenarios. (1) Three-dimensional transient dynamic analyses were performed to evaluate the strength of the cask`s end-closure clamp mechanism. The calculations were performed for two impact orientations: a side impact and a 20{degrees} corner impact. The calculations identified three weaknesses in the clamp design: a gap designed between the clamp and the cask provides a deformation mode which loosens the clamp, two unconstrained swing bolts used to fasten the clamp can lose preload and come free; and insufficient stiffness of the clamp in torsion. (2) An axisymmetric finite element model was used to evaluate the dynamics of end-drops from 5 and 10 ft. The calculations show that loads generated in the end-drops could break the payload support cable and damage the payload winch. Lead slump resulted in both end-drop calculations. The stresses generated in the cask wall during the end-drops was insufficient to cause buckling. (3) To determine the factor of safety to yield, calculations in which the cask was treated as a beam loaded under its own weight were performed for two support configurations: simply supported at both ends and simply supported at the center (trunnion loading). (4) The survival of the cask from a 1-m drop onto a mild steel punch was evaluated based on equations derived from empirical data. The calculations showed that the ST Cask could survive such an event. (5) Finally, the bolt configuration for the upper-closure was analyzed and determined to be inadequate because it does not prevent the closure from sliding relative to the cask body. Specific recommendations for design changes are made in the report to eliminate identified problems.