Monday, March 26, 2007

Future Submarine Power Plants: 100- to 1000-kw ?

Intriguing news - Cold Fission, would utilize liquid semiconductors to produce improved nuclear batteries. The U.S. Patent and Trademark Office posted a major patent application in November(excerpts):

Tsang, a former U.S. Energy Department researcher, was well aware of the beta cell’s problems. “Shoot a bullet into a block of ice, and the ice will shatter and can’t go back into its original form,” Tsang says. “But if you shoot a bullet into water, the water repairs itself.” So he began experiments replacing solid semiconductors with molten selenium and molten sulfur, both of which become semiconductors in their liquid state and melt at less than 300 °C. Because liquids don’t suffer any structural damage, Tsang’s nuclear battery could run on much more powerful radiation than a beta cell, and therefore generate more electricity.

A liquid nuclear diode could catch energetic alpha and beta particles, gamma rays, and even the new atoms left over from the fission of larger atoms, Tsang says. Fissile fragments could be a particularly good source of energy. In the fission of U-235, for example, the fragments carry 85 percent of the energy released. Because the fragments are heavy, as they plow through the semiconductor they “make a shower of electron-hole pairs along the path,” he says.

Although the prototype is still only 1% efficient, its promise impresses the U.S. Defense Advanced Research Projects Agency (DARPA).

With submarine power plants in mind, DARPA offered to pay GTI $26.6 million to prove the feasibility of a 100- to 1000-kw sized reactor. Obviously, prototypes can be undersized, but DARPA has been looking for direct (electrical) drive propulsion, smaller, cheaper boats and elimination of excess crew. Curiously, the operating temperature of the nuclear cold fission batteries is not expected to exceed that of a kitchen oven.



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