Category: Engineering

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 16. Liquid Fluoride Thorium Reactors will lessen the need for an expanded national grid.

Liquid Fluoride Thorium Reactors will lessen the need for an expanded national grid. The National Electric grid is at the breaking point. It needs to be expanded, but neighborhood resistance is building in many areas where they need an expanded grid the most. The grid is also sensitive to terrorism activities.

As we can see the national grid is extensive. It is also under severe strain at peak demand. Wind power will only increase the strain since most wind power is generated where few people live and work. A way to lessen the dependency on the national grid is to sprinkle it with many small to medium sized Thorium Nuclear Power generators.  They can be placed on barges in rivers and along the coast where the need is greatest,  giving the grid maximum flexibility to respond in  case of an emergency. (To be fair, the Texas grid is separately controlled from the rest of the grid.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 15. Liquid Fluoride Thorium Reactors will work both as Base Load and Load Following power plants.

Liquid Fluoride Thorium Reactors will work both as Base Load and Load Following power plants. LFTR’s operate at a much higher temperature than conventional power plants and operate at about 45% electricity conversion efficiency, as opposed to 38% or lower for steam generators. In addition, because of the higher operating temperature it is ideal for hydrogen generation. The reactor would use the electricity generation to satisfy the current demand and produce hydrogen during times of low demand. This hydrogen would be temporarily stored and used for electricity production at peak demand. And  hydrogen power produces only water when burned, no CO2  or polluting fumes are generated.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 14. No need for evacuation zones, can be placed near urban areas.

No need for evacuation zones, can be placed near urban areas. Molten Salt Thorium reactors operate at atmospheric pressure and have a very high negative temperature coefficient, so there is no risk for a boil-over. They are easily made earthquake-safe and no pressure vessel is needed. This will greatly simplify the approval process, no need for elaborate evacuation plans have to be developed. Since the Three Mile Island accident there was a thirty year gap in approvals for new nuclear plants. The “not in my backyard ” mentality reigned supreme, and delay and denial was the rule of the years. But the lawyers still got their share, leading to escalating cost for new nuclear power. In the early days of nuclear power France took the approach of building some of their nuclear plants near the Belgian and German border, so they only had to develop half of an  evacuation plan, leaving the other half to their understanding neighbors. It also leads to placing the nuclear plants where there is the least resistance, not where they are needed the most, adding to the strain on the electric grid.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 13. Thorium Nuclear Power generators  scale  beautifully from small portable generators to full size power plants.

Thorium Nuclear Power generators  scale  beautifully from small portable generators to full size power plants. One of the first applications was as an airborne nuclear reactor.

Granted this was not a Thorium breeder reactor, but it proves nuclear reactors can be made lightweight. Thorium reactors can be made even lighter as long as they are not of the breeder type.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 12. Virtually no spent fuel problem, very little on site storage or transport.

 Virtually no spent fuel problem, very little on site storage or transport. I am following the events at Fukushima Nuclear Power plants with great interest. How ironic that the greatest risk is with the spent fuel, not with the inability to shut down the working units. The spent fuel issue is the real Achilles’ heel of the Nuclear Power Industry. Molten Salt Thorium nuclear power works differently from  conventional Uranium as  the fissile fuel gets generated in the breeding process itself and nearly all fuel gets consumed as it is generated. When the process shuts down, that is it. Only the radioactivity that is en route so to say will have to be accounted for, not everything generated thus far in the process. The difference is about one to ten thousand in the size of the problem. It is high time to rebuild and expand our Nuclear power generation by switching to Thorium.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 11. Atmospheric pressure operating conditions, no risk for explosions.

 Molten Salt nuclear Reactors operate under Atmospheric pressure  conditions, no risk for explosions. Materials subjected to high radiation tend to get brittle or soften up. Molten Salt Thorium nuclear reactors operate under atmospheric conditions so the choice of materials that can withstand both high temperatures and high radiation is much greater, leading to a superior and less expensive design.  There is no high pressure gas buildup and the separation stage can be greatly simplified.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 9. Molten Salt Thorium Reactors cannot have a meltdown, the fuel is already molten.

With Molten Salt nuclear Reactors there is no risk for a meltdown, the fuel is already molten, and that is a safe design. The fissile fuel in a Thorium reactor is U-233 in the form of UraniumFluoride (UF4) salt which also contains Lithium and Beryllium. In its molten form it has a very low vapor pressure. The salt flows easily through the heat exchangers and the separators. The salt is very toxic, but it is completely sealed. Being a fluid, it is constantly mixed for optimum efficiency. The reactor will never have to be shut down for refueling, it is a continuous flow process. Uranium-235 Nuclear reactors on the other hand have to be shut down for refueling and rebalancing of the fuel rods a little more often than once every two years. The average shutdown is 35 days, or about 5% of the time. Then comes the major problem of safely and securely transporting and reprocessing the spent fuel.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 8. Molten Salt Thorium Reactors are earthquake safe.

Molten Salt Thorium Reactors are earthquake safe. Thorium reactors have a very simple and compact design where gravity is the only thing needed to stop the nuclear reaction. Conventional nuclear reactors depend on external power to shut down after a SCRAM, where poison rods fall down to halt the reaction.  The next figure shows the concept of a Thorium reactor.

The idea is to empty the fissile U-233 core through gravity alone. All that is needed is a melt-plug that is constantly cooled by cold air. In an earthquake the cold air flow automatically shuts off, and since the fuel is already molten, it will then run down into channels like pig-iron into cooling heat exchangers with  water supplied through gravity alone.

As we can see the reactor hardened structure is compact, and can be completely earthquake and tsunami proof. What can be sheared off are the steam pipes and external power, but the reactor shutdown will complete safely without additional power, even if the earthquake is so bad the reactor is broken into pieces.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 7. Produces isotopes that helps cure certain cancers.

Produces isotopes that helps cure certain cancers. For decades, medical researchers have sought treatments for cancer. Now, Alpha Particle Immunotherapy offers a promising treatment for many forms of cancer, and perhaps a cure. Unfortunately, the most promising alpha-emitting medical isotopes, actinium-225 and its daughter, bismuth-213, are not available in sufficient quantity to support current research, much less therapeutic use. In fact, there are only three sources in the world that largely “milk” these isotopes from less than 2 grams of thorium source material. Additional supplies were not forthcoming. Fortunately, scientists and engineers at Idaho National Laboratory identified 40-year-old reactor fuel stored at the lab as a substantial untapped resource and developed Medical Actinium for Therapeutic Treatment, or MATT, which consists of two innovative processes (MATT-CAR and MATT-BAR) to recover this valuable medical isotope.

The need to develop Thorium based Nuclear Energy as the major electric energy supply. 6. Thorium based nuclear power is not suited for making nuclear bombs.

 Thorium based Nuclear Power does not produce Plutonium239, which is the preferred material used in nuclear bombs. The higher Plutonium isotopes and other TRansUraniums are about as nasty as they get, and need expensive protection against terror attacks, and need to be stored for a very long time.

One anecdote from my youth. The time had come to apply to University, and to my delight I was accepted to Chalmers’ University in Sweden as a Technical Physics major. I felt, maybe I can do my part by becoming a Nuclear Engineer and help solve the energy needs of the future. The Swedes at that time championed the heavy water – natural Uranium program together with the Canadians. Sweden is a non-aligned country, so it was not privy to any atomic secrets, it had to go it alone. They settled on the heavy water moderated natural Uranium process because Sweden had an ambition to produce its own nuclear bomb. Officially this was never talked about, and I was not aware of it at that time. They could have gone with Thorium instead, but a Thorium based nuclear reactor  produces very little Plutonium, and what it produces is PU-238, not suitable for bomb making.

I was excited to learn about all the possibilities and signed up for a couple of nuclear classes. One lab was to design a safety circuit, then run the heavy water research reactor critical and hopefully watch the reactor shut down from the safety circuit before the system safety circuit shutdown. About that time the word came that U.S. will sell partially enriched uranium at bargain basement prices if Sweden agreed to abandon the heavy water project and sign the nuclear non-proliferation treaty, a treaty being formulated by U.N.

Sweden was in awe about U.N, all the problems of the world were to be solved through it, and it had such capable General Secretary in Dag Hammarskjöld, a Swede. I looked at the light water, partially enriched Uranium nuclear power plants being developed and decided to have no part with it, not due to safety concerns but it was the design that produced the most nuclear waste of any of the available designs. At that time there was still optimism that fusion would be ready by about the year 2010 or so. The cost of maintaining spent fuel in perpetuity was never considered, so light water reactors became the low cost solution.

India on the other hand refused to join the nuclear non-proliferation treaty, kept their heavy water program going and had by 1974 produced enough plutonium for one nuclear bomb, which they promptly detonated. They still use heavy water moderated reactors, but since India is low on Uranium but rich in Thorium they have now converted one heavy water reactor to thorium with a Plutonium glow plug. It went on-line in 2011.

They are also developing molten salt Thorium reactors, but full production is still a few years off.

There we have it. We could have gone with Thorium from the beginning, but the cold war was on, and the civilian peaceful use of nuclear energy was still all paid for by nuclear weapons research and development. Once all the bombs we could ever need were developed the greatest asset of nuclear power became its greatest liability.