Deep under Sweden's soil could lie a solution to the UK's nuclear waste problem

Monday, March 10, 2008

Robin Pagnamenta in Oskarshamn, Sweden

Inside the cavernous hall of a nuclear storage plant in southern Sweden, an 18-tonne steel canister, bristling with tiny fins to draw out excess heat, is being hauled slowly through a hatch by a crane.

Packed with highly radioactive spent nuclear fuel from a reactor north of Stockholm, the canister is being made ready for 30 years of storage in pools sunk into the bedrock. Once it cools sufficiently, it will be placed permanently in a final repository deep underground.

Surrounded by picturesque pine forests, lakes and rocky islets, Oskarshamn might seem an unlikely location for the 4,705 tonnes of high-level waste that is the legacy of Sweden's 40-year nuclear programme.

But to many in the industry, this unassuming plant on the shores of the Baltic represents the most advanced method yet developed for handling nuclear waste - and offers valuable lessons for Britain as it embarks on the construction of a new generation of nuclear reactors.
Related Links

Britta Freudenthal, of the Swedish nuclear waste management company SKB, offers a sobering insight into why most countries have found decisions over the handling of this hazardous material so difficult.

Were the fuel rods to be withdrawn from their protective canister and into the open air, “you would need to be at least 20km away to be safe from the radiation they emit”, she says. Furthermore, they will remain highly radioactive for 100,000 years.

But while Britain has dithered for decades over where and how to dispose of its own, larger store of high- level nuclear waste - most of which remains at a temporary facility in Sellafield, Cumbria, Sweden has quietly set about finding a practical solution.

“It doesn't matter whether or not we are committed to building any more reactors or not,” says SKB's Jenny Rees. “We need a safe place to store the waste we have already created. It is our responsibility to future generations.”

That is why the Swedish Government this year will pick a site for its final repository from two possible locations, including one just a few kilometres from Oskarshamn, with construction due to start in 2012. Both communities have volunteered to host the site and support its construction.

But it has taken 30 years to get this far. Meticulous studies of the country's bedrock to identify a geologically stable site have been accompanied by intensive research on how to package and store the waste safely for such an extended period of time.

Once the final repository is built by about 2018 at a cost of £1.8 billion, Sweden's spent nuclear fuel will be taken from the interim store, encased in solid steel and then welded inside five-metre-high canisters made from pure copper 5cm thick.

The canisters will then be transported into a deep underground store, about 400 to 700 metres beneath the surface - any deeper and the pressure of the surrounding rock would be too high.

At the rate of roughly one per day, they will then be placed in cylindrical vaults bored from the surrounding crystalline granite and embedded in Bentonite clay - a material similar to cat litter - that absorbs excess water.

Swedish scientists believe that in these conditions, the 6,000 canisters planned for the repository should be safe for 100,000 years, possibly even longer.

While SKB, a joint venture co-owned by four power companies including Vatenfall and E.ON, has not yet begun building its final repository, it has built a full-sized demonstration project at Oskarshamn.

Descending through the 3.7-kilometre tunnel blasted from solid bedrock to 400m underground is an eerie experience.

The silence is broken only by the noise of five huge pumps that extract 1,200 litres of water per minute. Test sites monitor everything from the growth of microbes to different ways of gently depositing the canisters in their vaults.

The work carried out by SKB is paid for from a levy on electricity bills. Since its creation 30 years ago, it has raised SKr38 billion, about half of which has been spent on the research programme so far. The fund also pays for decommissioning of nuclear power stations as they are retired from service.

One reason why Sweden has got so far with the project has been the nuclear industry's insistence on full transparency and public consultation throughout.

Tens of thousands of visitors come to visit the site every year, making Oskarshamn's nuclear plant one of the municipality's top tourist attractions.

“Transparency is the key word here,” says Linnea Sandwall, a spokesperson for SKB. “It's very important to meet people to show them what we do. There are no secrets.”

It is a lesson the UK nuclear industry, with its history of cover-ups and hushed-up accidents, would do well to study as it gears up for a new build programme.

Posted in |