STRUCTURAL EVALUATION OF A HIGH CAPACITY NON-WELDED BASKET DESIGN

Higher capacity baskets for storage and transport ofspent fuel provide an advantage ofALARA during loading operations and optimal use of space on the storage location. In this paper the impact analyses for a system to store and transport 87 BWR fuel assemblies are presented. The basket is a series of tubes with pins positioned at the tube corners (slots) to prevent relative motion of the tubes during the accident. With the absence of welds, immediate fabrication advantages are identified and flexibility mitigates stresses arising from thermal expansion. In the storage condition the overpack shown is a thick carbon steel liner inside a 20 inch thick concrete cylinder where as for the transport condition the overpack is a transport cask consisting of a lead lined multiple cylinders. In each condition, the gap between the canister and the overpack is different as well as the decelerations associated with the accident condition. This requires separate analyses to be performed for each. Initial evaluations decoupled the basket from the overpack response during the accident conditions, but the review process resulted in evaluation of a full length canister model with a detailed model of the basket contained in the canister. Two types of evaluations are performed; an evaluation of the geometric stability due to fabrication tolerances and a detailed evaluation of the deformation of the pin-slot region. The loadings employed in the evaluation consist of deceleration time histories obtained from separate models for the storage cask and the transport cask. While the paper will present an overall explanation of the generation ofthe loadings on the basket, the principle focus is on the basket response. Results for the basket evaluations indicate that the geometric positioning ofthe fuel is maintained during the accident conditions for both storage and transport scenarios.