Increase in capacity for interim storage of spent fuel
The extension project of the interim storage of spent fuel, which started in the summer of 2010, has now been completed in most parts. The extension doubles the capacity for interim storage of spent fuel assemblies from the Olkiluoto plant units. The safety features of the storage were also improved during the extension project.
After fuel assemblies have been unloaded from the reactor and stored in the reactor pool, they are transferred to the interim storage of spent fuel for cooling in water pools for several decades. At present, there are about 7 000 assemblies in the interim storage. When the fuel assemblies have cooled enough, they will be transported to the final disposal repository to be built in Olkiluoto. According to plans, final disposal activities will start in the early 2020’s.
More space, improved safety
The need for the extension resulted from the increase in the amount of spent fuel from the existing plant units and in the future also from Olkiluoto 3. The extension project was also planned to encompass an upgrading of the safety features of the storage.
Project Engineer Tommi Virtanen from TVO’s Building Engineering organisation is pleased with the status of the project.
– In addition to storage capacity, we have increased also e.g. options for supply of cooling water through new systems and fire-fighting equipment. I&C systems have also been replaced and the temperature and level measurement systems of the pools, for example, are more accurate than before. Covers to be placed on the fuel pools constitute a completely new safety feature.
The extension project that has now been completed increases the volume of the storage to ca. 90 000 cubic-metres. Concrete structures in the old part were also renovated and the ventilation and fire detector systems renewed during the project. High earth embankments designed to protect the facility against external safety and security hazards will still be constructed round the storage.
Precisions at several phases
Mr. Virtanen estimates that the final operating licence for the new part will be obtained towards the end of the summer. Finishing works are currently under way in the facility. Commissioning inspections are also carried out according to various commissioning programmes.
– The purpose of preoperational testing is to verify that equipment and components function as planned. Final documentation must also be completed and reviewed.
The project has employed some 80 subcontractors on the worksite. Companies from western Finland, in particular, are represented among cooperation partners.
– The spirit has been good in our project. Despite the special features of nuclear power plant construction, which make it more complex than normal building, our cooperation with the subcontractors has been smooth. Compliance with good safety culture in all subareas of the project is important to a good end result, concludes Mr. Virtanen with satisfaction.
Inspection of storage pools is extremely meticulous work.
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