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Toshiba Builds Ultra-Small Nuclear Reactor
DeusExCalamus writes "Toshiba has developed a new class of micro size Nuclear Reactors that is designed to power individual apartment buildings or city blocks. The new reactor, which is only 20 feet by 6 feet, could change everything for small remote communities, small businesses or even a group of neighbors who are fed up with the power companies and want more control over their energy needs."
20 feet high, 6 feet in diameter.
Oh, and this is old. I believe it was around 3 years ago that I first heard of this. They were talking about installing one in a remote village up in Alaska that gets all it's power from diesel because it'd be too expensive to connect it to the grid it's so far away.
Then the greenies* heard about it and killed it. The villagers were pretty much all for it.
*Can't really call them NIMBY, unless they count the entire planet their backyard in this case.
I don't read AC A human right
6Li is a neutron absorber. Its advantage is that it produces essentially no gamma radiation, as the dominant channel is 6Li(n,T). Tritium is produced, but in a reactor like this it will presumably be all inside the seals. The alternative shielding material, 10B, produces gammas as well, requiring lead shielding.
The lithium is a regulator and shielding component of the reactor, not a fuel. It'll be fuelled by moderately enriched uranium, much like a Slowpoke.
Interesting fact: 40% of electricity generated in Canada is lost to transmission lines and conversions. One of the big gains from tech like this would be the reduction in transmission losses.
After crawling the web a bit I found a few more interesting links about Toshiba's "Micro-Nuke" technology. First an article from 2005 about a similar Toshiba reactor running on liquid Sodium that was slated to be installed in a remote Alaskan village some time before 2010. This doesn't appear to be the same reactor as mentioned here on /.
A blog entry with more information and links about this and other small reactors.
It seems to be fairly safe, though I can't imagine the red tape they'll have to get through in order to begin installing them, especially in North America. The Nuclear Regulatory Commission in the US has about a 60 month process to certify a reactor from the time the application is filed, Toshiba probably has a head start on this application from 2005 with its "4S" mini-reactor, but this new Lithium version will probably need its own application process. They plan to build these things at least 30m underground, encased in steel and concrete walls that probably put most bank vaults to shame, so I don't think tampering will be a major issue.
Murphey's fighting Occam, and we're in the stands.
Spy,
To address your points:
"...uranium is kept in small pebbles made of graphite, which is a neutron reflector material."
Technically, graphite is a neutron moderator, to allow the neutrons to slow down and interact with other nuclei in the fuel matrix. The Chicago Pile 1 used the graphite bricks as the moderator matrix. The downside of graphite is that if a graphite fire starts, it's very difficult to put out. So the pebble bed isn't quite the ideal, IMHO.
"Both reactor designs have a "negative temperature coefficient of reactivity" simply means that an increase in core temperature will cause a decrease in core power. "
This is but one part of current regulatory requirements. The General Design Criteria govern the design of nuclear plants in general, and cores in particular. The downside of having too strong of a negative temperature coefficient is that in an overcooling scenario, you get the opposite effect. This is why Main Steam Line Breaks are considered in the core design.
"More interesting facts: pebble-bed reactors use helium as coolant instead of water..."
Personally, I've always liked the gas-cooled (especially He) reactors. BTW, this has been done before at Fort St. Vrain in Colorado. Unfortunately, because it was a first of a kind (here in the US, anyway), it was plagued by more mundane issues, like seal leakage, etc. Nothing catastrophic, but a pain in the ass operationally.
Sodium on the other had was intended to minimize the impact of metal corrosion. Think about it: with a liquid metal coolant, the fuel, piping, etc. would maintain integrity pretty well. The bad thing is that yes, Na is a dangerous thing to deal with - especially on a large scale. The Experimental Breeder Reactor in Idaho was one such, I think. This is where a lot of the operational problems were discovered.
We learn by doing.
Hope this helps.
Science never settles, never rests.