Bomb proof

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President George W Bush8217;s new nuclear energy initiative is supposed to help cure America8217;s 8220;addiction to oil8221; by redesigning a taboo technology, originally used to obtain plutonium for bombs, to reuse spent nuclear fuel. Unlike past reprocessing methods, the administration says, the new technique would make it prohibitively difficult for would-be proliferators to extract weapons-grade plutonium from spent fuel

Reprocessing technology was first developed by the US in the 1950s as a way to obtain plutonium for nuclear warheads, but President Jimmy Carter banned it in 1977 because of proliferation concerns. President Ronald Reagan rescinded the ban in 1981, but even then, reprocessing was so expensive and technologically daunting that no US power company ever sought to develop it.

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 8216;8216;once through8217;8217; 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 fuel8212;about 2,000 metric tonnes annually8212;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 8216;8216;transuranics8217;8217; and lighter radioactive elements known as 8216;8216;fission products.8217;8217;

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 8216;8216;fast reactor8217;8217;, 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 8216;8216;pyroprocessing,8217;8217; 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.

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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: 8216;8216;This is a matter of developing future technologies, and those technologies are 50 to 60 years away.8217;8217; Kraft endorsed Bush8217;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: 8216;8216;You can get a one-kiloton explosion with impure plutonium, and if you8217;re a terrorist the most important thing is to have the capability.8221;

The Washington Post