Cleaner energy

Cleaner energy

Could hybrid plants be used to fight world hunger and the global energy crisis?

UT researchers think they might.

Physicists at UT Austin have designed a new system that would use fusion to eliminate nuclear waste.

The invention could help combat global warming by making nuclear power cleaner and a more viable replacement for carbon-heavy energy sources such as coal.

“We have created a way to use fusion to relatively inexpensively destroy the waste from nuclear fission,” says Mike Kotschenreuther, senior research scientist with the Institute for Fusion Studies (IFS) and Department of Physics. “Our waste-destruction system, we believe, will allow nuclear power — a low-carbon source of energy — to take its place in helping us combat global warming.”

Toxic nuclear waste is stored at sites around the United States. Debate surrounds the construction of a large-scale geological storage site at Yucca Mountain in Nevada, which critics say is costly and dangerous. The storage capacity of Yucca Mountain, which is not expected to open until 2020, is set at 77,000 tons. The amount of nuclear waste generated by the country will exceed this amount by 2010.

The physicists’ new invention could dramatically reduce the need for additional or expanded geological repositories.

“Most people cite nuclear waste as the main reason they oppose nuclear fission as a source of power,” says Swadesh Mahajan, senior research scientist.

The scientists propose destroying the waste using a fusion-fission hybrid reactor, the centerpiece of which is a high-power Compact Fusion Neutron Source (CFNS) made possible by a crucial invention.

The CFNS would provide abundant neutrons through fusion to a surrounding fission blanket that uses transuranic waste as nuclear fuel. (Transuranic waste is nuclear waste that is heavier than uranium.) The fusion-produced neutrons augment the fission reaction, imparting efficiency and stability to the waste-incineration process.

Kotschenreuther, Mahajan, and Prashant Valanju, of the IFS, and Erich Schneider of the Department of Mechanical Engineering report their new system for nuclear-waste destruction in the journal Fusion Engineering and Design.

Their process would ultimately reduce the transuranic waste from the original fission reactors by up to 99 percent. Burning that waste also produces energy.

The CFNS is designed to be no larger than a small room, and much fewer of the devices would be needed compared to other schemes that are being investigated for similar processes. In combination with the substantial decrease in the need for geological storage, the CFNS-enabled waste-destruction system would be much cheaper and faster than other routes, say the scientists.

—  Lee Clippard