Underground rock cavities in south-east Sweden will contain radiation threat for 100,000 years, say scientists
Hervé Morin
Guardian Weekly, Tuesday 13 July 2010 14.00 BST
The bus stops after travelling 3.5km underground, taking us to a depth of 500 metres. We are near the Oskarshamn nuclear power station in south-east Sweden. Water is dripping steadily from the crystalline rock. "It is pumped out at a rate of 1,700 litres a minute," says Jenny Rees, the spokeswoman for SKB, a company set up by Swedish electricity utilities to manage nuclear waste.
In 1995, Sweden launched a project to study ways to store depleted fuel from its 10 nuclear plants. Whereas France is obsessed with finding rock formations that stop water from circulating, here the approach is based on a moist environment. "Other rock formations would be preferable, but we don't have them," says Björn Dverstorp, of Sweden's Radiation Safety Authority (SSM).
So the Swedes adapted their system to suit local conditions. They plan to encapsulate depleted fuel rods – unlike France there is no reprocessing here – in copper-coated cast-iron canisters. Some 6,000 of these boxes will be required for the waste from existing power stations, but their number is due to increase following the decision by Sweden on 17 June to gradually replace its 10 reactors.
After being stored for 40 years in special pools, where part of the residual heat wears off, each canister will be set into a cavity, subsequently plugged with bentonite, a rock that swells up in a moist environment and stops water from circulating. But will that be sufficient to contain the radiation for 100,000 years?
All over the world a strange slow-motion race is on to answer the tricky question of how to dispose of waste, some of which will remain radioactive for millions of years, without endangering future generations. The US will have to look for a new site, having abandoned its Yucca Mountain repository where a crack has appeared. Germany has 43,000 cubic metres of waste stacked up without additional protective measures in a leaking salt mine. In Belgium a decision has been postponed for 10 years to enable an underground laboratory to continue investigating how clay reacts to heat released by the storage canisters.
So Sweden is among those that have made the most progress. At the end of the year SKB will file a formal application to build an underground storage facility and in 2025 it will launch the transfer of waste fuel currently cooling in ponds at Oskarshamn. Finland, which is working on a similar technical solution, could follow suit shortly.
France also hopes to commission a repository by then but seems to have made less progress at the administrative level. Only in 2014 will nuclear authorities be filing an application to build a storage facility near the Bure underground laboratory in eastern France.This article originally appeared in Le Monde
