The Rise of Small Nuclear Plants

ColdWetDog writes "The Oil Drum (one of the best sites to discuss the technical details of the Macondo Blowout) is typically focused on ramifications of petroleum use, and in particular the Peak Oil theory. They run short guest articles from time to time on various aspects of energy use and policies. Today they have an interesting article on small nuclear reactors with a refreshing amount of technical detail concerning their construction, use, and fueling. The author's major thesis: 'Pick up almost any book about nuclear energy and you will find that the prevailing wisdom is that nuclear plants must be very large in order to be competitive. This assumption is widely accepted, but, if its roots are understood, it can be effectively challenged. Recently, however, a growing body of plant designers, utility companies, government agencies, and financial players are recognizing that smaller plants can take advantage of greater opportunities to apply lessons learned, take advantage of the engineering and tooling savings possible with higher numbers of units, and better meet customer needs in terms of capacity additions and financing. The resulting systems are a welcome addition to the nuclear power plant menu, which has previously been limited to one size — extra large.'"

Comments

This is good.

[elucido]

Nuclear energy is probably the best chance we have are breaking our addiction to oil. Nuclear energy is also relatively clean. I don't know why the government doesn't just fund the development of a bunch of nuclear power plants and put them on the coast or on the ocean somewhere. We could generate enough power to power the entire country, not to mention we could probably put hundreds of thousands of nuclear power plants in the desert.

Re:This is good.

[JackCroww]

I recently was part of a discussion about energy here in the US and this was my brother's contribution:

It's quite simple, actually. The United States has not built a nuclear power plant since the seventies. Almost all of the plants we built then, and all of the plants that are still online, are pressurized light water (PLW) designs. This means that that coolant in the reactor, which also moderates the nuclear reaction, is ordinary water under great pressure (typically at least twice the industrial norm of 600 lb/in^2 steam). A PLW reactor produces as much plutonium 239 as it consumes uranium 235. We erroneously call Pu-239 nuclear waste, and the governments since the Clinton Administration have been looking to find a place to bury it for a quarter of a million years.

However, until the Clinton administration, your government was busy designing a better reactor. The program was called integral fast reactor, or IFR. IFR was a metal-moderated reactor. The coolant was liquid metal, sodium or lead. These elements don't moderate the neutrons, they fly unhindered through the pile. That means they can fission Pu-239. In fact, they can fission anything higher than uranium on the periodic table. That's not all a fast reactor can do, though. It can also turn anything on the other (left) half of the bottom row of the periodic table into fissionable material. That's what "fast" means in the name. The reactor produces its own fuel from thorium or uranium in its natural state! Just the uranium that has been mined to date, which we use for cannon shells once we've taken the U-235 out of it, is sufficient for 300-400 years of the US energy needs. The known reserves are good for 50,000 years or so. Uranium is more plentiful in the earth's crust than gold or tin, and there is three times as much thorium as uranium. Energy forever.

What does "integral" mean? It means that the fuel is recycled on-site. The fuel in the IFR is in metallic, rather than ceramic form. It is simply re-smelted periodically (not the whole load, just a few rods' worth), and the slag is the only waste. The balance of the fuel plus a tiny bit of uranium or thorium in its natural state, is recast into pellets and returned to the reactor. The volume of the nuclear waste is reduced by several orders of magnitude. The nature of the waste is only the light elements that are the products of the fission reaction. They have either extremely short half lives, measured in seconds to months, or such long half lives that they are essentially stable. They are also mainly low-energy beta emitters, instead of neutron and gamma emitters. While this waste is hellishly radioactive at first, it will be less radioactive than uranium ore in less than 300 years, and reactors might produce a couple hundredweight in a fifty year lifespan, instead of thousands of tons of spent fuel rods as a PLW reactor would.

Additional benefits of the IFR design? The fuel is in metallic form, suspended in liquid metal. It gets no hotter than the coolant, and thus cannot have a catastrophic loss of coolant, or "blow down", which is what happens if there is a leak in the primary circuit of a LWR. The fuel in a LWR is in ceramic form, and gets much hotter than the coolant (which is in turn much hotter than liquid sodium). If it were not continuously cooled, it would destroy its container and melt, hence the term "melt down." If that happens to enough fuel elements in a reactor, the fuel gathers at the bottom of the vessel and continues to react, until it melts through the bottom of vessel, or the "china syndrome." None of these is possible with the IFR design. As it gets warmer, the fuel assemblies expand and move away from each other, slowing or stopping the reaction. The IFR, in fact, was tested for this. They turned off the control system. The reactor heated slightly, and stopped working. The cut off the heat exchanger (simulating what happens if the heat exchanger or a turbine goes bad at a LWR plant)--same thing. The reactor heated slightly and shut itself down,

Re:This is good.

[RsG]

Even if you use all our nukes someone will still make it.

Depends on how you use them.

If the cold war had gone hot, most of those nukes would have been aimed at targets in the northern hemisphere, with several warheads per target (as insurance, in case some didn't launch, didn't work, or got shot down). Contrary to popular belief, most of the targets were military, rather than civilian - cities were a low priority, missile silos were a high priority, for reasons that should be obvious. Post nuclear losses due to radiation poisoning, starvation and infrastructure collapse would probably have been higher than the actually death toll inflicted by the bombs, and as you correctly say, people would survive. Contrary to some predictions, nuclear winter would not have been likely, but we didn't know that at the time.

Now, if you actually wanted to achieve total human genocide using the worlds current nuclear arsenal, I'm not at all sure you couldn't. Don't bother with the cities, just hit all the arable land, and let starvation take its course. Of course that is a very morbid thing to consider, and is sufficiently horrible, not to mention suicidal, that we'd never actually do it, but you were discussing whether it was possible, rather than whether it was likely.

Re:This is good.

[DerekLyons]

If you got a bunch of engineers and said "figure out how to solve our energy problem", they could throw together a nuclear power system that could power the world into the next millennium - and it would be cheap, it would be clean, and it would be safe.

ADM Rickover thinks differently:

• An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose. (7) Very little development will be required. It will use off-the-shelf components. (8) The reactor is in the study phase. It is not being built now.
   
• On the other hand a practical reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.
   

Re:This is good.

[Anonymous Coward]

"The coolant was liquid metal, sodium or lead. These elements don't moderate the neutrons, they fly unhindered through the pile."

It's not all roses. For one thing these metallic coolants will all become highly radioactive themselves due to neutron activation, sodium is extremely chemically reactive (spontaneous ignition in air or H2 generation in water that then burns -- choosing non-reactive materials to go in the reactor primary coolant loop is a challenge too), and starting up/shutting down these things is tricky (solidified metal in the pipes is kind of inconvenient). Lead is trickier to work with because of its relatively high melting temperature. Lead-bismuth alloys with much lower melting temperatures are more typical, although unfortunately bismuth gets highly radioactive too.

The ability to use natural (i.e. non-isotopically enriched) uranium is not unique. The heavy-water-moderated CANDU reactors also have this ability. The main problem there is the cost of the heavy water.

IFR is an interesting reactor design but there are plenty of other options.

I also don't know why you consider the Clinton Administration the turning point for finding "a place to bury it for a quarter of a million years". That's been underway since 1982 at least (the Nuclear Waste Policy Act). Certainly there are options for using the "waste" as fuel rather than discarding it outright, but those options were discouraged by multiple administrations since the 1970s.

Re:This is good.

[MightyDrunken]

I'm not defending the GP's post but to describe nuclear power as cheap, at least historically, is not true.

The reason France's electricity is so cheap is because the government sets the price and has subsidised the cost. Recently EDF have been investigated for price fixing because of this.

The real reason why no nuclear power plants have been constructed for decades in many countries is mostly because gas and coal were cheaper. The fact that some considered it to be unsafe was a secondary issue. Now that gas prices are rising and there is growing concern about the environmental effects of coal, nuclear power starts looking competitive again.

The Navy?

[CohibaVancouver]

I would assume the nuclear plants found on submarines and large warships both provide a lot of energy and are not in the category of 'extra large.'

Thorium Power

[hydromike2]

The future of energy is in thorium. It a) cant be weaponized, b) is cleaner, c) does not need to be throttled up like uranium. They are developing these plants in other parts of the world such as india.