Sunday, December 23, 2007

Small Fission Reactors

There has been a rather interesting discussion in the comment section of a recent post here about the advent of small fission reactors for local power generation.

Lets start with this link to Next Energy News. First thing let me say that Next Energy news has had false reports from time to time and it is also heavily involved in fringe science such as zero point energy. Here is what they have to say:

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.

The 200 kilowatt Toshiba designed reactor is engineered to be fail-safe and totally automatic and will not overheat. Unlike traditional nuclear reactors the new micro reactor uses no control rods to initiate the reaction. The new revolutionary technology uses reservoirs of liquid lithium-6, an isotope that is effective at absorbing neutrons. The Lithium-6 reservoirs are connected to a vertical tube that fits into the reactor core. The whole whole process is self sustaining and can last for up to 40 years, producing electricity for only 5 cents per kilowatt hour, about half the cost of grid energy.

Toshiba expects to install the first reactor in Japan in 2008 and to begin marketing the new system in Europe and America in 2009.
No control rods OK. Good from a safety standpoint to avoid control rods in nukes. They can be a hazard as I will discuss below. However the question you have to ask is: how do they keep the reactor from running during shipment? There must be some method. What it is Next Energy doesn't say. Another important question is about the liquid lithium. It is highly reactive and corrosion will be a problem. The US Navy quit using liquid metal cooled reactors for that very reason. A third question is: is this just a heat producer or is electrical generation also part of the package? If there is electrical generation there is no mention of how it is done. If it is just a heat generator then it is most likely that water is used as the coolant. This is where the liquid lithium causes real problems. If the water is heated above the boiling point it will have to be pressurized. That means a heat exchanger. If the lithium comes in contact with the water in the heat exchanger (or any where else) there will be at minimum corrosion and possibly a chemical explosion. Not good.

So let us see if we can find out more. Instapundit is also covering this story and provides some links.

Discarded Lies has some stuff on it and a link to a story from 2005. 2005? Yep. It must be a hot story. Latest news. etc. Well, what do they have to say?
The small town of Galena, Alaska, is tired to pay 28 cents/kwh for its electricity, three times the national average. Today, Galena "is powered by generators burning diesel that is barged in during the Yukon River's ice-free months," according to Reuters. But Toshiba, which designs a small nuclear reactor named 4S (for "Super Safe, Small, & Simple"), is offering a free reactor to the 700-person village, reports the New York Times (no reg. needed). Galena will only pay for operating costs, driving down the price of electricity to less than 10 cents/kwh. The 4S is a sodium-cooled fast spectrum reactor -- a low-pressure, self-cooling reactor. It will generate power for 30 years before refueling and should be installed before 2010 providing an approval by the Nuclear Regulatory Commission.
Well there is some very interesting stuff there. Like sodium cooling. As I said. Next Energy is not very reliable when it comes to news stories. That fast spectrum stuff is a point against it as well. It means no moderator in the reactor. Which is good. It also means that it is harder to control due to the fact that a fast spectrum reactor produces fewer delayed neutrons. Delayed neutrons are what make a reactor controllable. Maybe I can find more about this with further effort.

Here is another link from Instapundit Alaska Village Moves from Diesel to 'Micro-Nuke'. Note this story is from 2005.
The design is described as inherently safe, but it does have one riskier feature: It uses liquid sodium, not water, to draw heat away from the core, so the heat can be used to make steam and then electricity.

Designers chose sodium so they could run the reactor about 200 degrees hotter than most power reactors, but still keep the coolant depressurized. (Water at that temperature would make steam at thousands of pounds of pressure a square inch.) The problem is that if sodium leaks, it burns.
So it does have a steam generator and a steam powered electrical plant. And they are going to keep all this sealed for 30 years with no maintenance? I don't believe it.
Toshiba calls its design the 4S reactor, for "super-safe, small and simple." It would be installed underground, and in case of cooling system failure, heat would be dissipated through the earth. There are no complicated control rods to move through the core to control the flow of neutrons that sustain the chain reaction; instead, the reactor uses reflector panels around the edge of the core. If the panels are removed, the density of neutrons becomes too low to sustain the chain reaction.
Ah. So they do have to control the sucker. What do you use to reflect fast spectrum neutrons? Uranium is traditional. Peachy. Neutrons absorbed in the uranium will tend to produce Plutonium. This is a feature not a bug. However, the use of Uranium as a reflector is just speculation. Maybe we can find out how it is really done. BTW this reactor seems to have a lot in common with an early American reactor (don't you just love the finish on the wood?) called Clementine which dropped a reflector to shut down the reactor in an emergency.

The Alaska Journal from Dec. 2004 has a few words.
The analysis showed that, presuming the nuclear battery went into operation in 2010, by 2020 it could supply electricity to Galena for 5 to 14 cents a kilowatt hour (kWh), assuming the reactor is a gift from Toshiba and the community pays only operating costs.

In comparison, improved diesel generation could provide Galena power for 25 cents to 35 cents per kWh. Coal-fired power comes in as a serious alternative in the study, at 21 cents to 26 cents per kWh, Chaney told the mining group. A small coal-powered plant could use coal extracted from a thick coal seam about 12 miles from the community.

The nuclear option looks good even if Galena were to pay for the reactor. In that case the power costs were estimated at 15 cents to 25 cents per kWh in the study, Chaney said. Toshiba has estimated the cost of the 4S reactor at $25 million. Galena's power is now 28 cents per kWh.

However, the nuclear costs vary so much because of uncertainty over the number of security guards the federal NRC may require at the site, Chaney said. Toshiba told SAIC that if the NRC's current regulations are followed, 34 security guards would be needed at the Galena site.

Chaney said a terrorist attack in a small, isolated rural community like Galena is unlikely because an unknown outsider would quickly be recognized. The 4S unit would be encased under several feet of concrete, "and if people show up with jackhammers, everyone in town will be aware of it."

A more appropriate staffing for security might be 4 guards, augmented by a state trooper and Galena city police who are nearby, Chaney said. If the NRC accepts that, the operating costs will be low enough to deliver electricity for 5 cents, according to the study.
They must be getting those guards for minimum wage. i.e. 5¢ a KWh for a 200 KW reactor is $10 an hour fully burdened. A real confidence builder that. I wonder if they get vacation pay?

I looked around and couldn't find a thing on this from Toshiba. None of the sites have a link to the Toshiba so I can get actual detailed technical explanations. I wonder why?

So let us go back in history and look at one of the first small nukes. It was a different design from the Toshiba nuke, but its history is very interesting. The small Army nukes didn't work out so well. The rods were manually operated. Which led to America's first nuclear accident with fatalities. There were three guys in the reactor bldg. One of them was banging one of the other guy's wife. The guy whose wife was getting it from his "friend" yanked a rod from the SL-1 reactor and caused a melt down. Murder/suicide. The rod itself was propelled by the steam explosion through the yanker's stomach and pinned him to the ceiling. I saw the pictures. Ugly. The other guys were killed as well. Clean up was a real mess. I was in Idaho in winter of '65/'66 at Naval Nuke Power School when the story was still fresh. None of the sites I have visited mentions the social situation. Except for the suicide explanation without details. Well any way, an object lesson to be careful around nukes.

You can look up the SL-1 accident. A site called Brain Candy casts doubt on the social situation theory.

Now a days we have terrorists. How do you protect 10,000 of these suckers from terrorism?

The proliferation of small nukes is the stupidest idea I have ever heard. I want big nukes with lots of armed guards and heavy material barriers.

The Navy quit using sodium cooled reactors because they were prone to corrosion leaks in the steam generator. The gas cooled ML-1 didn't work out well either.

The problem with nukes is that they have many years worth of energy stored in them. Not so with fusion plants. Let us hope we get working fusion before too many of these jobs get built and distributed. Like this possibility: Easy Low Cost No Radiation Fusion.

I could see such nukes used in a guarded industrial processes. Sitting unguarded in your local neighborhood? Too risky. Once you add guards the cost of electricity goes way up because of the low capacity. Not enough KWhs to spread the cost sufficiently. You are back in the price range of oil plus you have all the problems of nukes. Plus the Alaskans are getting the reactor for the cost of the fuel. Suppose they had to pay for everything? Not much left over advantage.

It makes no sense.

Cross Posted at Classical Values


Anonymous said...

Another problem with small nukes is that they're essentially heat engines, and themodynamics says that small heat engines are inefficient. Too much heat is lost. If you want an efficient heat engine it must be as large as possible. That also happily means that security and infrastructure costs will be low, relatively speaking.

Anonymous said...

I'm not seeing the security issue here. If the unit is properly installed then you're "theives" would need construction equipment to reach it, a crane to raise it and a large flatbed to haul it away.

A whole helluva lot of equipment and work when it would be simpler to raid a chemical plant for a couple gallons of phosgene to commit some terrorist/anarchist act.

As far as the logic of using Galena. Look up the history of the place in it's relation to the US military during the early cold war.

RightWingNutter said...

FWIW see page 1 of

Note that this is from the Toshiba Japan site.