Development of a family of Robust Shielded Containers for the Storage, Transport and Disposal of Intermediate Level Waste

Typically in the UK, Intermediate Level Waste (ILW) is retrieved, sorted and encapsulated in a cement grout within thin walled stainless steel waste containers. Two main approaches to packaging have been employed:Unshielded packages, for higher activity ILW which require remote handling and shielded facilities for storage as well as separate shielded containers for transport in the public domain.Shielded packages, for lower activity ILW. Due to their integral shielding these designs are capable of being handled using standard industrial equipment and stored in simple stores that allow for controlled man access.In both cases, performance of the waste package is met by the combination of the wasteform and the container. In contrast, an innovative type of self-shielded container, typically manufactured from ductile cast iron, named Robust Shielded Containers (RSCs), is being pursued by a number of site license companies. RSC’s place little or no reliance of its performance on the wasteform and this approach simplifies the waste retrieval and packaging processes which can have significant cost and programme and hazard reduction benefits.For any waste package one of the most onerous performance requirements is the performance in impact accident conditions, representing drop accident scenarios during interim storage, transport in the public domain and during operations at a Geological Disposal Facility.This paper summarises the design development by Croft Associates Ltd on its SAFSTORE range of RSCs and presents the work undertaken by Arup for Croft Associates Ltd on the impact performance of the SAFSTOREs, including:impact analyses to define the geometric details of the containers;material test programme (a) to define the stress strain behaviour of the material at a range of temperatures and at different strain rates, and (b) to define the failure behaviour of the material with strain rate and tri-axiality;material level benchmarking to derive material properties suitable for finite element analyses, to estimate failure and to validate the material model;design, manufacture and physical impact testing of a prototype container; and pre-test analyses to estimate the behaviour and post-test benchmarking to validate the analysis model