A court in Sweden yesterday approved plans to excavate a repository for nuclear waste, the Barron’s news site reports.

The decision clears the way for a construction project that will have to meet a unique criterion: remaining structurally sound for a period of 100,000 years.

Sweden has already earmarked a site for the tomb, 500m below the soil in Forsmark, about 130km north of Stockholm on the Baltic coast. This is also the site of one of the country’s three nuclear power plants.

The Land and Environment Court granted the Swedish Nuclear Fuel and Waste Management Company (SKB) a permit to begin construction at the site.

The court also granted a construction permit for another site at Oskarshamn, also on the coast about 300km south of the capital.

This second site will host an interim storage facility to store the waste until it “cools”, or decays into more stable elements.

Then it will be embedded in cast iron and placed in copper canisters before being transported to Forsmark aboard the M/S Sigrid, a cargo ship designed by SKB with a number of enhanced safety feature, such as a reinforced double hull and watertights bulkheads.

When the process is in full swing, the plant will be able to process about 200 canisters a year, each weighing about two tonnes.

According to the court, the repository will be able to hold a maximum of 12,000 tonnes of waste.

“Operations are expected to run for around 70 years but can be extended, if for example the reactors’ life spans are extended,” the court said.

Altogether, SKB expects the future costs of the waste management programme to be $11.1bn.