Documenting the Coming Singularity

Tuesday, March 03, 2009

This is not a Terminator - TR10: Traveling-Wave Reactor

Technology Review - March/April 2009, by Matt Wald

A new reactor design could make nuclear power safer and cheaper, says John Gilleland.

Wave of the future: Unlike today’s reactors, a traveling-wave reactor requires very little enriched uranium, reducing the risk of weapons proliferation. (Click here for a larger diagram, also on page 3). The reactor uses depleted-uranium fuel packed inside hundreds of hexagonal pillars (shown in black and green). In a “wave” that moves through the core at only a centimeter per year, this fuel is transformed (or bred) into plutonium, which then undergoes fission. The reaction requires a small amount of enriched uranium (not shown) to get started and could run for decades without refueling. The reactor uses liquid sodium as a coolant; core temperatures are extremely hot--about 550 ºC, versus the 330 ºC typical of conventional reactors. Credit: Bryan Christie Design

Enriching the uranium for reactor fuel and opening the reactor periodically to refuel it are among the most cumbersome and expensive steps in running a nuclear plant. And after spent fuel is removed from the reactor, reprocessing it to recover usable materials has the same drawbacks, plus two more: the risks of nuclear-weapons proliferation and environmental pollution.

These problems are mostly accepted as a given, but not by a group of researcher­s at Intellectual Ventures, an invention and investment company in Bellevue, WA. The scientists there have come up with a preliminary design for a reactor that requires only a small amount of enriched fuel--that is, the kind whose atoms can easily be split in a chain reaction. It's called a traveling­-wave reactor. And while government researchers intermittently bring out new reactor designs, the traveling-wave reactor is noteworthy for having come from something that barely exists in the nuclear industry: a privately funded research company.

As it runs, the core in a traveling-­wave reactor gradually converts nonfissile material into the fuel it needs. Nuclear reactors based on such designs "theoretically could run for a couple of hundred years" without refueling, says John G­illeland, manager of nuclear programs at Intellectual Ventures.

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