Development of low enriched uranium plus (LEU+) enrichment capability and the associated impacts on criticality safety

Urenco is an international supplier of enrichment services, operating centrifuge uranium enrichment plants in Germany, Netherlands, United Kingdom (UK) and United States of America (USA). Current operations at these facilities produce Low Enriched Uranium (LEU), which is enriched up to a maximum of 5 weight-percent uranium-235 (% enrichment) for delivery to customers. Urenco has identified a market need to supply marginally higher uranium enrichments in the range of 5-10% enrichment, with this range referred to as Low Enriched Uranium Plus (LEU+). Urenco is currently developing the capability to produce LEU+ at its' UK and USA enrichment facilities using the existing installed capacity. A key factor for implementing the desired LEU+ capability is demonstrating the criticality safety of existing facilities at an elevated uranium enrichment required to support the desired LEU+ activities. This paper discusses the range of impacts identified on criticality safety as a result of the proposed LEU+ operations, as well as Urenco's approach to addressing these impacts across two different facilities with differing regulatory regimes. This includes impacts on the criticality safety assessments for enrichment and ancillary supporting facilities, criticality emergency planning arrangements and fissile material transport. (author)