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Portable Nuclear Battery in the Development Stages
Xight writes "The Santa Fe Reporter has up an article about a portable nuclear reactor, about the size of a hot tub. Despite it's 'small' size the company that is planning to develop the product (Hyperion Power Generation), claims it could power up to 25,000 homes. 'Though it would produce 27 megawatts worth of thermal energy, Hyperion doesn't like to think of its product as a reactor. It's self-contained, involves no moving parts and, therefore, doesn't require a human operator. "In fact, we prefer to call it a 'drive' or a 'battery' or a 'module' in that it's so safe," Hyperion spokeswoman Deborah Blackwell says. "Like you don't open a double-A battery, you just plug [the reactor] in and it does its chemical thing inside of it. You don't ever open it or mess with it."' If all goes according to plan, Hyperion could have a factory in New Mexico by late 2012, and begin producing 4,000 of these
reactors."
I'm pretty sure the person editing this made a big cockup when they changed "Like you don't open a double-A battery, you just plug it in and it does its chemical thing inside of it. You don't ever open it or mess with it." The "it" obviously refers to the Double-A battery, and whoever edited the copy got it wrong.
This device is not a reactor, even though it uses nuclear power.
This thing is called a "Radioisotope thermoelectric generator".
It is nothing new, they were used on the Voyager spacecraft.
They can be much smaller or larger than a bathtub, as the article says.
http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
Wierd. First, it's not a "nuclear battery". Those have been around since the 1950s, and they typically have quite modest power output, from a few watts to a few hundred watts. They're just some radioactive material decaying at its normal rate; they don't use a chain reaction. If this thing is supposed to produce 27MW, it has to be a real nuclear reactor.
And it is. Here's the patent application, out of Los Alamos National Laboratory. The basic idea is this: "This present invention achieves control by utilizing the properties of a fissile metal hydride as a self-contained nuclear fuel and neutron energy moderator. If the physical size, fissile metal content and enrichment are appropriately selected, the metal will absorb ambient hydrogen, which moderates the neutron energies so that nuclear fission criticality is achieved. The temperature will then be increased by the fission reactions until the dissociation pressure of the hydrogen for that temperature is greater than the ambient pressure of the hydrogen, at which point the hydrogen dissociates from the hydride and the source becomes sub-critical." So that's the way it self-regulates. It's supposed to operate at a constant temperature; if you remove heat with a working fluid, it produces more heat; if you don't, it stabilizes at its normal operating temperature. It's a uranium reactor, using 5% enriched uranium. Runs at 350C to 800C. Uses heat pipes to get the heat out to a working fluid, probably water, used to make steam and drive a turbine.
It's not clear if this is a workable design. There's no prototype. But it's at least plausible. It's not a totally new idea; the TRIGA reactors are self-regulating in a somewhat similar fashion.
The "Los Alamos Study Group" that made critical comments has nothing to do with Los Alamos National Laboratories. Their director "worked as a transportation planner, natural foods manufacturing entrepreneur, high school teacher, hazardous waste investigator, and contaminant hydrologist."
It is also pretty apparent that you've never seen a nuclear reactor. A reactor itself is pretty small compared to the overall size of a plant. It's the cooling loops, turbines, myriad of control and power equipment, and containment structure that take up space.
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