Thursday, April 12, 2007

Crazy Nuke Idea #1

I don't know enough nuclear physics (yet - I intend to know everything someday, though I also understand on an intellectual level why this is impossible) to tell if this is a good idea or not, but I was thinking:

(digression)
The holy grail of nuclear power physics is nuclear fusion. Presumably we would never have to worry about energy again if we had fusion reactors. I think people assume this because of the abundance of hydrogen in the universe. While it's true that hydrogen is the most abundant element in the universe, we don't have any shortage of uranium or thorium (on earth).

However, these reactors appear to me to be extremely complicated rube goldbergs compared to the simplicity of our fission plants. They require giant magnetic plasma traps to keep plasma spinning in large evacuated chambers. They require creating enough fusion reactions with this plasma to allow for drawing enough energy off of it (how? I've heard either thermally or through some sort of magnetic induction) to turn some sort of electric generator to feed enough power back into the magnets to keep the reaction going. So far, we don't seem to have reached anywhere near enough fusion/input energy to get this to work. While I've read about reaching breakeven for scattered microseconds on research devices, it doesn't appear that we've reached it on average for any extended period of time on a device.

Furthermore, even when we get it to work, building and operating these plants sounds like a pain in the butt. You have an extremely unstable reaction that could stop sustaining itself if anything goes out of whack. You have massive construction costs for the magnetic coils and vacuum chambers. You probably have massive operating costs because of the attention that these devices will require by plasma physicists.

So … I don’t know how often I’ve heard the sentiment expressed: Fission is old, inefficient (??? Efficiency needs a lot of qualifiers to mean something, you know), and dirty. Fusion is clean, efficient (???), and much much better. It is the way of the future.

Why this sentiment if 1) We can’t get it to work yet, 2) When we do get it to work, it will almost certainly be more complicated and expensive to operate, even taking insane regulation of fission and the need to process the waste into account. It’s almost like hearing “SSTO Reusable Spaceplanes are the Wave of the Future ™” over and over again, when I know why they can’t work.

Furthermore, where nuclear fission reactors have been scaled to some extent to fit in all sorts of situations (silent power for submarines, the ability to push the navy carriers around in the ocean without a direct oil pipeline back to shore, experimental rocket engines, proposed remote mini-reactors, ect) I’m not sure if a tokomak can scale that easily. You need to hit that reaction/reactor ratio before you can produce power.


If we ever do get fusion power to work, then cool. There are many planets in the solar system that don’t have heavy metals like uranium available in the quantity that they are here on Earth. If we had a tool like that under our belt, we would never run out of fuel in the lifetime of the universe. I just don’t see how, if you’re a city manager with a situation where you have ready access to uranium, you make the decision to build something 10x more complicated and expensive than you have to.

(/digression)
That said, here’s my crazy idea:

These tokomaks are trying to collide light elements together with sufficient energy to cause a fusion reaction. Light elements usually have high proton to neutron ratios, meaning that they have low mass/charge ratios. The nuclei will tend to veer away from each other, unless they are traveling at each other with large velocity and angular precision.

Heavy elements, on the other hand, have much lower proton to neutron ratios. How much easier would it be to collide heavy nuclei in a heavy ion plasma with the intention of fissioning the nuclei than to attempt fusioning light nuclei? Could you sustain a tokomak fissioning a heavy ion plasma where you couldn’t sustain it with a fusioning plasma?

Variation #2:

Current fission reactors use fissile uranium (U-235), however there is something like 100x more U-238 (the stable uranium isotope) in naturally occurring uranium.

Furthermore, thorium, a lighter element, is being looked at because its reactions don’t result in elements heavy enough to be used in nuclear weapons. If you used some sort of reactor based primarily on thorium, you wouldn’t have to worry about proliferation. You could trust this technology to anyone without worrying if they’ll convert it over to producing nuclear weaponry. Thorium also happens to be even more abundant than uranium.

Currently the thorium reactions are being sustained by uranium rods, because the thorium won’t sustain the reaction on it’s own. Not enough neutrons created and absorbed per reaction to keep the thing going.

I’m wondering if it’s possible to sustain a thorium fission reaction by firing a beam of heavy ions through the material. Heavy fast ions collide with thorium nuclei -> nuclear chaos happens -> maybe enough neutrons are generated to trigger enough reactions to make the rod hot? Could you generate enough energy from the reaction to run the particle accelerator sustaining it? If so, you could have a reactor that

1) Could never melt down because it requires active input to sustain the reaction (but not quite as much active input as required to run a fusion reactor) (though modern uranium reactor designs also can claim this feature)
2) can’t be used to make nuclear weapons material
3) might be more economically competitive because it doesn’t need as heavy a containment dome (possibly doesn't need one at all) No danger of internal superheated metal or high pressure steam, if the whole thing can be regulated by the particle accelerator breaking/turning off. No inspectors or guards to keep the materials out of terrorist hands.

I wonder if it could be scaled down enough to use on a car, or in a home? Maybe a nuclear powered aircraft that doesn’t need gasoline and has no range limitations?…

I’d love to see the nuclear revolution re-started after the hysteria of the 70s. I’d love to see this powerful, compact, nearly endless source of energy powering our cities, factories, ships, and spacecraft (you can do a lot with a nuclear rocket engine). The “energy crisis” (we’re running out of oil) or “carbon crisis” (we use too much oil), these hysterical (even longed for by some fanatics) visions of mankind being forced back into a cowed, limited, pre-industrial agrarian zero-sum state (with solar panels) doesn’t make any sense at all with nuclear energy firmly in our grasp. The most maddening thing about it is that it almost was, and that what keeps us from using it isn’t any engineering or technological hurdle, but entirely self-imposed legal limitations!

3 Comments:

Anonymous Gordon said...

First, you pretty much hit the nail on the head with your comment on AeroGo. I left a lengthy reply there.

Regarding your recent posts, that's a great photo of Io. I had a paper route back in the 70s, and I still remember picking up the stack of newspapers one afternoon and seeing the photos of the erupting plumes on Io. There was a lot of evidence something must be going on, yet folks were still rather surprised to discover active volcanism elsewhere in the solar system.

I think the extracellular matrix stuff is probably for real. I've read something similar elsewhere. There's a huge revolution going on in biotechnology, and most of society really doesn't see that, yet, how progress is being made on so many fronts. It's going to be bigger than the computer revolution, I suspect.

I don't know if your nuke ideas are crazy or not, since I don't really know much about nuclear engineering, but it's certainly time for the field to apply some fresh thinking. As messed up as our space strategy has been, it's been way more intelligent than the U.S. strategy for nuclear technology.

Breeder reactors were a promising technology back in the 80s, with many potential advantages, but I haven't heard anything about them in a long time. The U.S. research stopped, but the French, who have had the best nuclear energy program in the world, were pursuing it. That's one of those things I keep telling myself I need to look up on the internet.

I wrote over a year ago about the resurgence of interest in nuclear, and I recently added a comment there about how China and India, who are agressively pursuing nuclear energy, are going around the world locking up uranium sources.

I'm glad to see nuclear is being taken seriously again. Even just a few years ago, folks would laugh at proposals. We're nowhere near where we should be in developing nuclear technologies, whether for Earth or space.

The price of electricity is much higher than it should be at this point in our technological development, a realization which has been made by a lot of the big computer users. The cost of computing has dropped so radically, that the electricity cost has nearly gotten as high as the cost of the computer hardware!

Thursday, April 12, 2007 11:37:00 AM  
Blogger James Caeran said...

A clean nuclear approach: abundant energy without greenhouse gasses or proliferation concerns.

Nuclear's greatest secret – we can have clean inexpensive electricity without the significant downsides that have slowed the growth of nuclear power in the past. All that is required is to return to the road not taken fifty years ago.

Worldwide the demand for energy is growing at an increasing rate. China, India and other developing countries will bring hundreds of millions of their citizens into the industrialized world over the next two decades. As they do this, they will compete with the established economies of the West and Japan for resources. Absent a breakthrough, this means the construction of hundreds of new power plants that run on fossil fuels – plants that will spew tons and tons of greenhouse gasses and worsen our already overburdened atmosphere.

Although a considerable amount of progress has been made on renewable forms of energy such as solar and wind, these long term options won't be enough for some time to come. In years past, the nuclear option was held in poor regard by many environmentalists, but the reality – nuclear power keeps 700 million metric tons of carbon dioxide out of the atmosphere in the US alone – over 2 billion tons worldwide - has lead many in the movement to accept that nuclear power must have a place in the energy mix. This despite lingering concern over the threat of proliferation and the issue of what to do with radioactive waste.


These downsides of nuclear power, however, all flow from a fundamental decision made long ago – to use uranium fuel in almost all of the nuclear reactors in the world.1 And uranium fuels by their very nature produce massive amounts of weapons usable material, including plutonium, and generate even larger amounts of highly toxic nuclear waste.




There is a better way. The first commercial nuclear power plant in the world, in Shippingport, Pennsylvania, ran on a thorium-based fuel. Thorium, a naturally occurring element two down from uranium on the periodic chart, can be used in reactors but doesn't have the serious downsides uranium fuels do. The Shippingport plant, designed by the then chief scientist of the US Naval Reactor Program, Dr Alvin Radkowsky,(Co-founder of the publicly traded company Thorium Power) operated successfully for a number of years before it was shut down. The industry moved to uranium-based fuels, however, partly to mask military demands for weapons usable plutonium, thus creating a global shift towards uranium fuel & research.



In 1992 Thorium Power was incorporated to develop nuclear fuel designs based on thorium to stop the production of weapons suitable plutonium and eliminate existing plutonium stockpiles. This resolve in research has lead to new technological advantages in the nuclear industry:

Thorium has a much higher melting point than uranium and operating temperatures of Thorium Power's fuels are significantly lower than those of conventional uranium fuel, thus significantly reducing the risk of a melt down;
Thorium Power's fuels significantly reduce the amount and long-term radio-toxicity of spent fuel (approx. 50% reduction in volume of spent fuel);
Thorium Power's fuels provide enhanced proliferation resistance. They are not suitable for production of weapons-usable material;
Thorium Power's fuels offer improved economies; and
Thorium Power's fuels can incinerate reactor-grade plutonium recovered from spent uranium fuel while producing electricity
Thorium Power's research has been conducted at premier Russian nuclear institutes, including Kurchatov Institute, OKBM, Bochvar Institute, MSZ Electrostal, Siberian Chemical Combine, VNIPIET, and others, where they have access to over 500 Russian nuclear engineers and scientists. The funding for this project has come from private investors and US government DOE grants. Most recently, in May of 2006, the company successfully completed a $15,000,000 private placement in anticipation of a October 6, 2006 reverse merger as a publicly traded company.

In 1985 global investment in the nuclear industry came to a virtual halt. In the United States alone the Federal spending on R&D for nuclear projects dropped 89% during this time. So it should come as no surprise that with an aging global nuclear work force, Thorium Power's extensive research, expertise, and vast intellectual properly portfolio, has lead to interest from governments, businesses and non-governmental organizations like environmental groups.



Thorium Power's "Seed & Blanket approach"

Alvin Radkowsky's Thorium based design incorporates both mechanical and nuclear physical features that past engineers failed to grasp. He worked around the drawbacks of thorium and uranium and came up with a solution specifically for today's reactor. This is why the Company sometimes refers to their fuel as "the fuel for reality".
Thorium Power fuel designs are for existing and future "light-water (and pressure-water) reactors." These reactors make up 70% of today's market. In the future if nuclear technology migrates to the "fast-breader reactors," Thorium Power's technology will prove suitable and compatible. With a focus on today's problem we will analyze how Thorium Power's technology works and what makes it not only essential, but feasible.

The first step is to understand how uranium works in a reactor. There are two isotopes of uranium in the core... fissile and fertile. This is the typical set up for nuclear fuel. Fissile Uranium-235 comprises 4% of the nuclear fuel and produces the power in the reactor. Fertile Uranium-238 comprises 96% of the nuclear fuel (as a moderator) and does not provide the power.

Since Uranium-235 is fissile, meaning it is radioactive, neutrons are continually flying off it. Some of those neutrons hit other Uranium-235 atoms, splitting them (fission), and in the process release heat. This heats up the water in the reactor, making steam that spins a turbine and produces electricity. However, the neutrons do not know that they are supposed to hit the Uranium-235 atoms, so some of them hit Uranium-238 atoms. Uranium-238 absorbs the neutron, becoming Uranium-239, which decays into Plutonium-239. This is the nuclear weapons-usable isotope of plutonium.

The fissile Uranium-235 is burned down as the process moves along.
In essence, fissile Uranium-U-235 producing energy does not contribute to proliferation or significantly to waste. It's the 96% fertile Uranium-238 in the fuel that creates the problem...and it doesn't contribute to anything, except as a helper in the process.

Thorium can be used as a fertile material to replace Uranium-238 thus eliminating the resultant weapons-usable plutonium and other highly toxic nuclear wastes. This process leaves Uranium-235 in the reactor. You can also replace U-235 with plutonium from existing stockpiles, where the plutonium acts as the fissile material powering the reactor while burning down the plutonium to dispose of it. This leads to a fuel that eliminates plutonium, stops the reactor from making more weapons-usable plutonium, and makes much less waste and significantly less toxic waste.


That's where Thorium-232 comes in. Thorium is fertile. The key to the reaction is that when a neutron hits thorium, it does not create weapons grade plutonium. Instead, the Thorium-232 absorbs a neutron and becomes Protactinium-233, which decays into Uranium-233. Since Uranium-233 is fissile, when it gets hit by a neutron it splits, creating more energy in the reactor. In fact, Uranium-233 is more fissile than the original Uranium-235 (which is exactly what commercial grade fuel is) in the fuel. It is because of this characteristic that thorium actually makes more fuel for the reactor. Therefore, the fuel lasts longer in the reactor, resulting in less spent fuel and waste for the same electricity produced, with little to no plutonium. Very simply, this is a much more efficient process than conventional nuclear fuels.

The problem past nuclear engineers (and physicists) came across was that thorium and uranium burn at different rates, making it inefficient in a commercial reactor if they are configured similar to conventional fuel assemblies. In the core of the reactor some components of the fuel rods largely burn out (Uranium-235), while other parts would just keep going (Thorium-232). Fuel rods containing fissile Uranium-235 or Plutonium-239 can be optimized to burn in 3 years, while thorium- 232 with some added uranium can be optimized to burn up to 9 years in the core.

Alvin Radkowsky provided the solution. He simply placed the fissile Uranium and the thorium into separate fuel rods. Hence, the " Seed and Blanket" configuration. The seed (or center) contain the fissile Uranium-235 (or Plutonium-239) and the blanket (the outer setup) contains the thorium. He then devised a system that would allow the seed to be exchanged about once every three years while the blanket would stay in the reactor for up to nine years. The seed will do its thing and burn itself out while the blanket, with the thorium, will get bombarded by neutrons flying off the seed and the small amount of uranium in the blanket fuel rods. In the process it produces Uranium-233 and more energy with very little waste left. Certainly no weapons-suitable Plutonium
Thorium Power is positioned as a " PURE PLAY " in a nuclear renaissance. Over the next few decades we will likely see hundreds of new nuclear power plants come on-line. Thorium Power will strongly benefit from this development. The company is uniquely positioned as a key source, in global consulting on many existing and future nuclear industry solutions. Thorium Power is developing three primary nuclear fuel designs for existing and future light water reactors: (1) Thorium/uranium fuel that is being designed to be a substitute for conventional uranium fuel, (2) Thorium/reactor-grade plutonium disposing fuel that offers an economically viable alternative to MOX fuel, and (3) Thorium/weapons-grade plutonium disposing fuel that provides the more effective and less expensive way to incinerate excess weapons-grade plutonium in light water reactors than other existing reactor-based alternatives.



Mr. Seth Grae, CEO has assembled a world class team, to leverage the insight of this group of investment professionals to generate returns across a wide range of nuclear issues in a complex industry. The International Advisory Board comprised of key national and international leaders in the fields of Nuclear Energy, Finance, Government Affairs, Non-Proliferation and Diplomacy including Sir Ronald Grierson, (Co-Chairman of the Blackstone Group's Int. Advisory Board ) Dr. Charles W. Pryor, Jr. (USEC CEO ) Susan Eisenhower (President of the Eisenhower Group) and Ambassador Thomas Graham, Jr. (Chairman of the Board of Directors of Thorium Power)



Thorium Power Ltd. also has put together a Technical Advisory Board made up of top nuclear scientists and engineers from the world's major nuclear companies. Thorium Power Inc., a wholly owned subsidiary is a leading developer of proliferation resistant nuclear fuel technologies. The company designs nuclear fuels, obtains patent protection on these fuels and coordinates fuel development with governments and commercial entities and consortium's.




THORIUM POWER'S VALUE TO SOCIETY

Improved nuclear safety, reliability and affordability.

Maintains a viable nuclear option to addressing environmental problems with fossil fuels.

Maintains a global leadership position in safety, advanced designs and non- proliferation .


http://www.thoriumpowerinc.com/
http://www.thoriumpowerinc.com/

Thursday, April 12, 2007 6:23:00 PM  
Anonymous Gordon Vaughan said...

Hey, I don't recall which month it was that you wrote about radiation shielding (why does Blogger still not have categories?), but I thought you might be interested in this article from New Scientist about the Univ. of Washington's study of magnetic deflector shields for spacecraft.

"One group at the University of Washington in Seattle, US, has just completed a round of experiments investigating one possible approach, using a bubble of charged particles, or plasma, as a deflector shield (see Plasma bubble could protect astronauts on Mars trip).

Now, a second team has begun deflector shield experiments of their own. The team, led by Ruth Bamford of the Rutherford Appleton Laboratory in the UK, hopes to eventually fly a test satellite surrounded by a cloud of plasma in space."

I think I may have left a comment before with a link to that earlier article. This is a good example of a new space technology that really is likely to just sit around unused until someone actually does test-fly it. The need for space technology missions is a point I've been trying to emphasize on AeroGo.

Saturday, April 21, 2007 9:12:00 PM  

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