You might think it's a hoax, but read on....

Further information on the Toshiba mini-reactor can be found here and here...

A small-scale design developed by Toshiba Corporation in cooperation with Japan's Central Research Institute of Electric Power Industry (CRIEPI) and funded by the Japan Atomic Energy Research Institute (JAERI) is the 5 MWt, 200 kWe Rapid-L, using lithium-6 (a liquid neutron poison) as a control medium. It would have 2700 fuel pins of 40-50% enriched uranium nitride with 2600°C melting point integrated into a disposable cartridge. The reactivity control system is passive, using lithium expansion modules (LEM) which give burnup compensation, partial load operation as well as negative reactivity feedback. As the reactor temperature rises, the lithium expands into the core, displacing an inert gas. Other kinds of lithium modules, also integrated into the fuel cartridge, shut down and start up the nuclear reactor. Cooling is by molten sodium, and with the LEM control system, reactor power is proportional to primary coolant flow rate. Refuelling would be every 10 years in an inert gas environment. Operation would require no skill, due to the inherent safety design features. The whole plant would be about 6.5 meters high and 2 meters in diameter.

For much more, see Brian Wang's postings here and here.

I can see why people might think it's a hoax. Toshiba's official site has got nothing on it. Nevertheless, it would seem to be legit.

UPDATE: Title suggested by M. Simon, who has more.

(Bumped to the top by Eric, in a fit of Christmas Eve altruism.)

posted by Justin on 12.24.07 at 09:42 AM



Your post lacks a title.

I covered it in detail at Small Fission Reactors.

How about a link. :-)

M. Simon   ·  December 24, 2007 4:18 AM

The 4S reactor that Instapundit linked to uses Sodium coolant.

The New Energy folks are notorious for getting the story wrong.

Me? I wouldn't trust any fission reactor here on earth that didn't have an operator. I don't care how fool proof it is, the universe will always deliver up a bigger fool. Or even people with bad intent.

And liquid metal cooling? I really want to know a lot more about the design of their steam generator. I have yet to hear of one that was maintenance free for 10 years. And that is with water on both sides. Put a highly reactive liquid metal on one side and all bets are off.

I really don't like the small reactor concept. Too much stored energy. Read the history of SL-1. True it was a bad design. It does give an indication of what an "event" can do.

All designed eqpt. has a probability of failure. You have 100,000 of these out there operating for 30 years and the probability of catastrophic failure is almost certain.

They are especially dangerous if you depend on the coolant for neutron absorption. What happens if you have a loss of coolant accident? What happens if you get a slug of cold water in the steam generator when you are operating at high power?

MHD type pumps are not very efficient. What happens in a loss of electrical power accident? How do you extract the residual heat? Do you need a backup generator (diesel)?

Suppose you have a period of high power use and then the power use goes way down? How do you prevent Xenon poisoning from shutting down the reactor for 24 to 36 hours?

BTW cost of power of 5¢ to 7¢ a KWh does not take into account any guards required. Or operators. Or maintenance. Just the fuel cost.

Turbines (gas, steam) are high maintenance. Oil ages. Neutron flux breaks down chemicals and transmutes atoms. How do you do oil changes?

The devil is always in the details.

I do not doubt that with enough effort these concepts could be made to work. I'd like to see experimental operation of any new design for 10 or 20 years (including efforts to induce accidents) before I put them in any neighborhood. Even one in the Alaska wilderness.

M. Simon   ·  December 24, 2007 5:04 AM

There was an article on the Toshiba reactor in the NYT sometime in 2005, as I recall.

Jim Miller   ·  December 24, 2007 5:31 PM

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