Posiva yet another step closer to start of final disposal - STUK approves construction plan for Posiva’s extruded copper tube
Posiva moved yet another step closer to the start of the final disposal of spent nuclear fuel when the Radiation and Nuclear Safety Authority of Finland (STUK) announced having issued an approval for the construction plan of the extruded copper tube. The copper shell is one part of the final disposal canister and surrounds the canister insert made of spheroidal graphite cast iron. Together this construction provides the canister with high corrosion resistance and mechanical protection.
An extruded copper tube ready for machining does not yet look like a copper tube at this stage. Jouko Lammi, who is in charge of the canister manufacture, and EBS expert Matti Väinölä from Posiva seen in the background.
Posiva has for years studied and developed an appropriate extrusion process that fulfils the safety requirements, for use in the production of the copper tube. Dozens of test specimens have been produced of the tube together with SKB, the Swedish company in charge of the final disposal of spent nuclear fuel in Sweden.
However, the regulatory body had not assessed earlier construction plans adequate to demonstrate the fulfilment of the technical requirements specified for the tube.
“A significant, major step”
Programme Manager Petri Koho from Posiva considers STUK’s announcement great news as it means the final condition for the start of the production of the tube has now been met.
- This is a significant, major step towards the start of safe final disposal production. It is significant as it means we finally have an approved method for the production of the tubes. Thanks to all concerned.
Copper extruded through a mold
The extruded copper tube is produced by a method where copper is extruded through a mold to shape it into a tubular structure. This is a common method used to produce HVAC pipes, for example. Microscopic discontinuities or stresses may occur in the extrusion process. These can then affect long-term strength, particularly in a corrosion-sensitive environment. But now the manufacturing challenges have been solved, and STUK has approved the construction plan of the tube.
Posiva’s goal is to start the final disposal operations by encapsulating spent nuclear fuel in a final disposal canister at the ONKALO®-area’s encapsulation plant in Olkiluoto during the year 2026. The exact date can only be specified after all the licences and permits are in order.
Text: Pasi Tuohimaa
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