Successful implementation of an unattended safeguards approach for the transfer of spent fuel to interim dry storage

In today's commercial nuclear environment spent fuel bundles are being removed from wet storage areas, encased in containers or baskets and stored at interim dry storage facilities all over the world. Growing demand on resources are challenging the IAEA to develop better, more inventive ways for maintaining continuity of knowledge of the spent fuel while it is being transported by operator-controlled vehicles to facilities for storing large caches of spent fuel. This formidable task becomes less intimidating through inspector pre-planning, approved procedures and professionally installed, reliable containment and surveillance (C/S) equipment. Safeguards measures for transferring spent fuel under traditional safeguards include the on-site inspector who monitors the loading of spent fuel into transport/storage containers and constantly observes the item's physical location throughout transport to an interim dry storage facility. However, currently the number of inspector days in the field has been drastically reduced through the installation and operation of unattended monitoring systems that maintain continuity of knowledge of the spent fuel. Under a State-level approach to safeguards, spent fuel transfers may be monitored by a regime of unannounced inspections, with a low probability for post-transfer detection of a diversion of nuclear material. Through a combination of low frequency unannounced inspections and an unattended spent fuel transfer safeguards approach, the probability of post-transfer detection for a diversion are above 50%. The IAEA's unattended approach to the monitoring of spent fuel transfers has already eliminated the need for continuous inspector coverage and minimized the number of person-days required per facility, thereby allowing valuable inspector resources to be redirected to other, more demanding areas of the world for safeguarding efforts. Cernavoda Nuclear Site located in Romania is currently the first of its kind being safeguarded under an unattended spent fuel transfer approach. This paper examines the approach, viewed as a successful case study that has demonstrated the viability of the improved method for monitoring and maintaining continuity of knowledge of spent fuel being transferred from an operating CANDU reactor to an interim dry storage facility. (author)