IN July 1999, two heavily armed cargo ships began carrying 225 kilograms of plutonium-containing fuel rods half way round the world, from Britain to Japan. Now the Japanese are demanding that the cargo-suspect, unused and unwanted-be taken back.

The fiasco is one of the most embarrassing episodes in the 30-year history of the state-owned company, British Nuclear Fuels (BNFL). But looking beyond the immediate crisis, it has also raised doubts about whether plutonium really is what the industry has always dreamt it to be-the fuel of the future.

"Today, if you had tonnes of plutonium to offer for free," says Klaus Janberg, general manager of the German nuclear waste company GNS, "no one would take it." So, if the highly toxic metal that first came to fame as a nuclear explosive doesn't have a future in fuelling reactors, what on earth is to be done with it?

The plutonium shipped ...