NEK building dry cask storage

Krško – The Krško Nuclear Power Station (NEK) started building a long-planned dry cask storage on 1 March as part of its security upgrade. The construction of the storage is under way despite the scheduled one-month maintenance that started on Thursday. The project is to be concluded next year, said NEK CEO Stane Rožman.

Announcing the project a few years ago, Rožman said the investment would cost about EUR 60 million, with NEK covering two-thirds of the amount and the rest coming from the fund for NEK’s decommissioning.

NEK has so far been storing used fuel in a water pool is a standard manner of storage, but decided to improve safety by opting for dry storage, which is recognised as the most appropriate and widespread temporary storage method in the world.

It is a transition from active to passive solutions as no additional devices, systems or energy are needed to provide for cooling, Rožman said.

After obtaining a construction permit, NEK started preparing the site in March. The building will measure 50X70 metres and will have 80-centimetre thick walls of prestressed concrete, which will be six metres high. A 14-metre steel construction will be placed on top.

Inside the building, robust, impermeable casks for used fuel will be placed.

Božidar Krajnc, the director of engineering at Krško, told the STA a few years go that the transfer of fuel rods from the pool to the new 3,000 m2 storage facility would begin with about 600 fuel rods being transferred to 16 steel-and-concrete casks.

In the second phase, due to commence in 2025, an additional 16 casks will be filled. The final phase will be completed five years after the power station is due to shut down in 2048.

The storage facility will be built to last 100 years, whereupon the state will have to find other solutions. Krajnc noted that by then the technology would probably be far more advanced.

He explained that in the new storage facility, the steel-and-concrete casks will stand upwards with air circulating between the cask and the concrete envelope providing for cooling.

The steel casks will be inserted into concrete containers to provide for additional safety in case of stronger earthquakes.

The storage facility for spent fuel is separate from the repository for low and intermediate level radioactive waste which will be built in Vrbina, in the immediate vicinity of the power station. The Agency for Radioactive Waste is in charge of the construction of that repository.