Two design tweaks for boosting nuclear reactor efficiency

[phantom power]

(new fuel configuration)

Uranium fuel typically is formed into cylindrical ceramic pellets about a half-inch in diameter. The pellets look like a smooth, black version of food pellets for small animals.

In a three-year project completed recently for the U.S. Department of Energy, Hejzlar and Kazimi teamed up with Westinghouse and other companies to look at how to make a fuel for one kind of reactor, the pressurized water reactor (PWR), 30 percent more efficient while maintaining or improving safety margins.

They changed the shape of the fuel from solid cylinders to hollow tubes. This added surface area that allows water to flow inside and outside the pellets, increasing heat transfer.

The new fuel turned out even better than Hejzlar dared hope. It proved to be easy to manufacture and capable of boosting the power output of PWR plants by 50 percent.

(water additives)

The efficiency of PWRs and BWRs is limited to around 33 percent, because water can be heated to only a certain temperature and only a certain amount of heat can be taken out of water. If that limit were pushed higher, more heat could be extracted, and the plant would generate more energy at a lower cost.

This may soon be possible, thanks to Buongiorno.

His laboratory works on nanofluids -- base fluids such as water interspersed with tiny particles of oxides and metals only billionths of a meter in diameter. Buongiorno's nano-spiked water, transparent but somewhat murky, can remove up to two times more heat than ordinary water, making it an ideal substance for nuclear plants.

http://www.sciencedaily.com/releases/2006/09/060925154237.htm