Sweden's radioactive waste management company Svensk Kärnbränslehantering AB (SKB) has submitted an application to the Radiation Safety Authority, SSM, to extend the existing SFR final repository for low and intermediate-level waste at Forsmark. The company plans to expand the repository to almost three times its current size in order to receive demolition waste from decommissioned Swedish nuclear power plants.

The blue area shows where SKB plans to extend the existing SFR repository (Image: SKB)

The application includes, among other things, the preliminary safety analysis report (PSAR), a report on safety during the construction phase, system descriptions and a decommissioning plan. Only after SSM's approval can SKB start the work to excavate rock for the extension of the SFR.

Work on the PSAR has been ongoing since 2016, SKB noted, although in recent years it has been more intensive. It is significant work that has been carried out partly with updated analyses and partly with internal security reviews.

"The analyses are now updated with refined methods, data and calculations, while the conclusion from previous analyses remains firm: the plant is safe both during operation and after closure," said project leader Jenny Brandefelt. "It certainly feels satisfying that the updated analyses continue to show a safe facility in both the short and long-term".

The SFR repository is situated 60 metres below the bottom of the Baltic Sea and began operations in 1988. The facility comprises four 160-metre long rock vaults and a chamber in the bedrock with a 50-metre high concrete silo for the most radioactive waste. Two parallel kilometre-long access tunnels link the facility to the surface. The facility currently has a total final disposal capacity of about 63,000 cubic metres of waste.

Most of the short-lived waste deposited in the SFR comes from Swedish nuclear power plants, but radioactive waste from hospitals, veterinary medicine, research and industry is also deposited within it.

SKB applied in December 2014 to triple the size of the repository, to about 180,000 cubic metres. The application was submitted to the government by the Land and Environment Court and SSM in November 2019. In April 2021, the municipality of Östhammar, where the SFR is located, also approved the extension. Following a government decision in December 2021 to approve the application, the matter was referred back to SSM and the Court.

SKB received an environmental permit from the Land and Environment Court for the expansion in December 2022. That permit regulates, for example, noise and transport.

The plan is that the repository, when extended, will have six new rock vaults, 240-275 metres long. The intention is to construct the extension at a depth of 120-140 metres, level with the lowest part of the current SFR repository.

The expansion is expected to take six years to complete. In the initial stage, earthworks, water treatment plant and other infrastructure will be put in place. In the second stage, tunnelling work in the rock underground will be carried out.