Tuesday, November 27, 2007

Cleaner Nuclear Power?

Continued from page 1

By Peter Fairley

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Thorium Power plans to test this fuel system within three years, starting in a pressured-water reactor in Russia. The tests will be conducted in partnership with the Kurchatov Institute, a nuclear research center in Moscow. The institute has been testing the endurance of Thorium Power's fuel materials for four years while simultaneously scaling up a uranium-zirconium extrusion process to produce the 3.5-meter rods used in the Russian reactors.

If the rods endure, experts expect that Thorium Power's scheme will succeed because the hybrid thorium-and-uranium fuel concept is already proven. Several early gas-cooled nuclear reactors of the 1950s and '60s used a seed-and-jacket fuel scheme conceptually similar to Thorium Power's. And a few early water-cooled reactors such as the first reactor at Indian Point, NY, operated in the 1960s and '70s with fuel rods filled with a thorium-uranium blend. However, thorium fell out of favor as the nuclear industry standardized around uranium, particularly after uranium fuel slumped to rock-bottom pricing following the accident at Three Mile Island in 1979.

Dumping fuel every two years looks less appealing today, with uranium prices rising rapidly and high-level waste piling up at commercial reactors across the United States. Thorium fuel also responds to growing concern over proliferation of fissile materials that could be used in nuclear weapons. Thorium's byproducts produce intense gamma radiation, making them hard to handle by would-be bomb makers. Thorium Power is focusing its marketing efforts on developing countries in the Middle East, Asia, and Latin America that are looking to build their first reactors; Grae bets that a design that impedes proliferation of nuclear weapons will make reactors easier to finance in such countries. The company is also looking to India, which hopes to exploit its large thorium reserves.

The challenge for thorium proponents is that the DOE already advocates another fuel cycle that promises to cut waste and manage proliferation risks: a so-called closed fuel cycle, whereby chemical reprocessing recovers plutonium from spent uranium fuel for reuse in conventional reactors.

Reprocessing is central to the DOE's Global Nuclear Energy Partnership (GNEP), whereby major nuclear players such as the United States would guarantee uranium fuel supply to countries that promise to return spent fuel--the plutonium within which could be used to make nuclear weapons.

The GNEP has many critics who argue that the reprocessing of spent fuel will be costly, will increase rather than limit the risk of diversion of fissile materials, and will do little to reduce high-level waste volumes. The DOE's plan is to burn recovered plutonium by blending it with uranium. This produces a hotter and more toxic spent fuel that can only be burned in breeder reactors. Those reactors have, to date, proved infeasible at commercial scale. (See "The Best Nuclear Option.")

Grae insists that Thorium Power could benefit, in the long run, from stepped-up reprocessing because its fuel system provides a better outlet for the recovered plutonium: replacing uranium as the neutron source for Thorium Power's thorium-fuel rods. In 2005, nuclear-technology giant Westinghouse evaluated Thorium Power's system as an option for burning surplus military plutonium, and the company predicted that this would be "substantially" cheaper, quicker, and more effective than burning plutonium with uranium.

Cleaner Nuclear Power?

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