Type A shipping package harmonic assessment methodologies

Abstract

Response to incident vibrations is a design aspect assessed during the development of Type A fissile shipping packages. Not only are expected transport induced vibrations evaluated for package structural integrity, but also to ensure the integrity of the unirradiated fuel assembly. Such incident vibrations include, but are not limited to, expected transport induced vibrations, and single pulse shock inputs occurring at relatively high frequencies. The regulatory requirement to ensure that there is no deterioration in the effectiveness of any closure devices or in the structural integrity of a Type A fissile shipping package is governed by TS-R-1 as well as 10CFR71·71. In addition to regulatory requirements, the fissile Type A contents, more specifically the fresh fuel assembly, have design specifications that require shipping and handling acceleration loads remain below a design threshold. Other structural design considerations include supplemental vibration damping system(s) tuned for package design features and transport conveyance interfaces which may induce vibrations. A test program was developed and executed to fully assess the Westinghouse Traveller fresh fuel shipping package harmonic characteristics considering regulatory and fuel assembly requirements. Road course testing, vibration shaker table testing and port handling simulation/drop tests with production Traveller shipping packages were utilised for evaluation. The testing also provided valuable data to determine the proper material selection for shock mitigating materials, their configuration within the shipping package, and identifying resonance frequencies associated with the shipping package design structure. Once an in-depth understanding of the packaging and fuel assembly’s harmonic response to shipping and handling induced vibrations and single pulse shocks was established, an optimised suspension system design configuration to dampen those incident vibrations was realised.