Leading the way with Aging Management

Storing used fuel in licensed dry storage systems at reactor sites for long periods of time wasn’t originally anticipated: interim dry storage systems were originally designed and licensed for shorter storage periods, generally 20-40 years. Beyond this interim storage period, used fuel was planned to be transported to a geological repository or recycling facilities. Due to persistent delays in implementing geological repositories or the fuel recycling facilities, there is a need to extend dry storage beyond initial time period.The dry storage system needs to be designed and licensed to ensure that the necessary safety functions are maintained during long term period of storage and subsequent transportation after storage. Consideration needs to be given to potential aging deterioration of component materials that may occur during operation of the storage system.In the context of extended interim dry storage, investigations are currently being carried out to demonstrate and justify the ability of the structures, systems and components associated with dry storage to maintain their intended safety functions. Further, research is also underway to determine the behaviour of used nuclear fuel and its safe and secure storage for an extended period of time. Effective aging management programs require a technical understanding of the aging degradation mechanism, inspection and assessment techniques, prevention and mitigation measures (to retard the effects of aging) and, as needed, guidance on repairs or replacements for each component. These descriptions are part of the aging management program for the storage system which is developed for each potential degradation mechanism related to extended duration that could adversely affect structures and components important to safety.Regulators are in the process of defining a program to monitor and maintain dry storage systems on site to ensure of same level of safety and security. In this early stage of license renewals, aging management programs include mainly periodic inspections of the used fuel dry storage systems and components to ensure potential aging effects are identified and effectively managed. This paper provides highlights of issues related to managing effects on dry storage systems for long-term interim storage and transportation of used nuclear fuel and discuss innovative solutions being developed to monitor age-related degradation, prevent equipment failures caused by aging and develop contingency plans as needed.