Experiences of the operation of the interim storage facility for spent fuel at Olkiluoto

The spent nuclear fuel accumulated from the two nuclear power units Olkiluoto 1 and Olkiluoto 2 operated by Teollisuuden Voima Oy (TVO) at Eurajoki, Finland, are stored in the long term intermediate storage for spent fuel, the KPA Store. The designed operating life of the storage is 60 years. The spent fuel will be stored up to 40 years before it will be finally disposed of in the final repository for spent fuel to be build at Olkiluoto site and scheduled to commence in 2020. The KPA Store was commissioned in September 1987. The fuel is stored in water pools. Approximately 120 fuel assemblies are replaced annually in each reactor and stored for 1- 5 years at the facility before they are transferred to the KPA store. The transfers are usually made in campaigns every second year. During the operational time of the storage, 104 transfers have successfully been made and for the time being there are 4,264 fuel assemblies, 59 per cent of the capacity, stored in the pools. (author)