Licensing the UK's First Ever Multiple Water Barrier Package

The U.K Government has a strategic objective to consolidate fissile materials onto a single site. Inventory includes unused and spent Fast Reactor fuel and an assortment of fissile material from mainly UK nuclear establishments. The nuclear material was originally destined for reprocessing; the material had been put into short term storage in the 1980s/90, however following the closure of certain facilities in the 2000s a longer term storage solution was required. Difficulty inspecting the materials together with decades in storage had raised questions over the integrity of components (including mixed oxide fuel pins and mixed carbide sub-assemblies) following a decision not to re-package the materials for transport or leave in further longer term storage at the original site. It was decided a High Standard Multiple Water Barrier (MWB) Package will be required for the transport of the material to the new site. To enable the transport of high quantities of the radioactive materials with adequate margins of sub-criticality, it was necessary to demonstrate the exclusion of water from the proximity of the contents under all conditions of transport. International Nuclear Services proposed enhancing the design of an existing flask, the M4/12 into a High Quality MWB transport package. International Nuclear Services’ package justification was based on the M4/12 transport package providing the first line of protection with a newly designed inner container dubbed the Un-irradiated Fuel Container (UFC) providing the second water barrier. This newly designed UFC coupled with the M4/12 was approved by the Office for Nuclear Regulation (ONR) for use as U.K’s first High MWB package for transport under Special Arrangement. The paper will set out the process and approach that was taken by International Nuclear Services (INS) during recent application to the ONR the UK safety regulator for the civil nuclear industry, for the package approval. This paper will include details on the key aspects of the licensing process used, interpretation of the transport regulations, the difficulties encountered, how they were overcome and ultimately how INS achieved a right first time safety case.