Bomb proof

France, Japan, Russia, India and the UK do reprocess commercially, and all use the old US technology, called purex, which derives plutonium oxide from spent fuel and then combines it with uranium to create a mixed-oxide fuel, called MOX, that can be used in power plants. MOX is much more expensive than the uranium fuel in conventional reactors.

The conventional plants use ‘‘once through’’ fuel rods in a controlled reaction to produce steam that drives turbine generators. The rods are replaced every 18 to 24 months, and the spent fuel—about 2,000 metric tonnes annually—is put into temporary storage on the reactor sites.

The new technology, as described by Phillip Finck, deputy associate director for applied science technology and national security at Argonne National Laboratory , begins with a new reprocessing technique called urex-plus, which, like purex, dissolves spent fuel rods in a bath of nitric acid. The used fuel rods are composed of uranium, plutonium, heavy radioactive metals called ‘‘transuranics’’ and lighter radioactive elements known as ‘‘fission products.’’

Unlike purex, which separates out the plutonium, urex-plus leaves the plutonium and transuranics mixed together, making the resulting product unsuitable for weapons and more difficult to handle for anyone trying to build a bomb.

The new fuel would be used in a ‘‘fast reactor’’, where neutrons move about much more energetically than in conventional reactors, breaking down the long-lived transuranics into lighter fission products with shorter half-lives. The spent fuel from the fast reactor would be reprocessed using another new technology known as ‘‘pyroprocessing,’’ which separates the fuel by dissolving it in molten salt and running an electric current through it. The fuel can be recycled several times until the long-lived transuranics all but disappear.

If successful, the new reprocessing method will replace purex, the stockpile of civilian plutonium would stop growing, and the whole cycle would become much more proliferation resistant.

Steven Kraft, senior director of used fuel management for the Nuclear Energy Institute, an industry policy group, voiced doubts: ‘‘This is a matter of developing future technologies, and those technologies are 50 to 60 years away.’’ Kraft endorsed Bush’s plan as a worthy long-range goal, but nonproliferaton advocates said impurities in reprocessed plutonium are not likely to dissuade would-be proliferators from stealing it.

Arjun Makhijani, president of the Institute for Energy and Environmental Research, an energy think tank, said: ‘‘You can get a one-kiloton explosion with impure plutonium, and if you’re a terrorist the most important thing is to have the capability.”

(The Washington Post)