Russian scientists say they have turned plutonium from nuclear weapons into reactor fuel for the first time, using technology invented years ago but never used before now.

The claim by the scientists, at the Institute of Nuclear Reactors in the city of Dimitrovgrad, Ulyanovsk, is reported by the news agency Itar-Tass.

It says the scientists have already processed 8kg of plutonium using the new technology to heat the institute building and adjacent residential areas since the beginning of January. "The fuel they obtained will be enough for heating them until April," it adds.

Third millennium technology

Weapons-grade plutonium may now be used to generate electricity

The Russians are calling their new discovery "the technology of the third millennium", because it is a "dry" technology which allows weapons-grade plutonium to be turned into reactor fuel with the use of very little liquid.

This means a drastic reduction in the amount of waste to be disposed of, which in turn means the process will be much cheaper than the existing "wet" technology.

The director of the Institute, Alexei Grachyov, told Itar-Tass: "Humanity has accumulated thousands of tonnes of weapons plutonium, but we were the first to use it for peaceful purposes."

Worldwide interest

He said scientists from the US, Japan and other countries had shown an interest in the new technology and were offering help with continuing the Institute's research.

Plutonium from nuclear weapons has been offered for sale by criminals

A British nuclear expert who visited the Institute last year told BBC News Online the Russian technology has nothing to compare with it in the West.

"It is cheap, safe, and can operate on a small scale - so you have no problems with transporting the material, or with transporting waste afterwards. And it works as well with warheads as with spent reactor fuel."

Although this is the first reported use of the technology, its introduction was forecast last year by Russia's first deputy atomic energy minister, Valentin Ivanov. He told a meeting in London of the Uranium Institute that his country was considering making use of the dry technology.

Extreme temperatures

The new process is a pyrochemical technology which involves heating the material to extremely high temperatures. The plutonium oxide produced in this way is mixed with uranium oxide and can either be packed directly into fuel assemblies, or made into pellets.

If the technology works successfully on a large scale it could help significantly with one of the most intractable legacies of the nuclear age - the deadly mountain of plutonium which, at the moment, has to undergo a complex and expensive process to turn it back into useful fuel.