By Harry {doc} Babad, © Copyright 2011, All Rights Reserved.  Revision 2 (corrected 1/2/2012)


Over the years there has been On-N-Off again interest in using thorium rather then uranium to fuel our energy needs. The interest came in part because of the greater availability and more widely distributed quantities of thorium in the earths crust. In addition the a thorium based fuel cycle seem to be significantly, despite nay-sayers, more resistant to diversion to weapons production (proliferation.) Recent studies, both at design phase and pilot plant size demonstrations have demonstrated that in an appropriate rector, the thorium based fuel cycle can both grow its own fuel, and burn up uranium fuel cycle based spent fuel treated as waste.

There are also detail assessments of the costs of such alternative technology, which I’ve ignored in this article. Why? For the most part in my studies, all such cost studies overestimate the end costs. This is in part due to the use of pessimistic values of input data and the use of conservative modeling assumptions.

Figure 1. The (simplified) Thorium Fuel Cycle

The discussions that follow are encapsulated gleanings from the main articles I reference, all published in the last several years. In addition, I skimmed my collection 60+ document collections on the thorium fuel cycle reference that, go back to 2005.

I attempted, within the time I had available, to determine whether any of the older ‘paradigm’ basic assumptions had been wrong in their conceptualization of thorium use for energy production. I found none, however many of the earlier documents differed by their use of then less accurate state-of-the art models. Such models continuously evolve, get challenged and improve  to get more accurate. Technologically, we both get smarter mathematically and computing power grows in accord to Moore’s Law.

In parallel to computational development, more realistic definition of model inputs and available experimental data based on the physics, and chemistry of elements of the thorium fuel cycle have occurred.

The Basic Historical Nuclear Energy Facts as I Know Them

Nuclear energy worldwide is based on a Uranium Fuel cycle.

The non-Thorium elements in this article can be either researched in Wikipedia or just googled. They are no a part of my normal reference practices which tend to focus heavily on the main topics under discussion in these blogs. I do suggest to stick with engineering and science oriented sites or those of the much larger international site that under obsessive peer review by anti-nuclear types. It is better to check out facts than to fight the belief battle with those who have received guidance from small voices in their heads or they’re under technology educated neighbors or media fear mongers.

Uranium fuel use for electrical energy generation is a legacy of US and German weapons development during WW II. At that time the US goal was to beat Nazi German to the super weapon punch. The allies won in Europe against Adolf Hitler and the Nazis by convention means including carpet-bombing of bother German cities, factories and infrastructure.

However to win the parallel war with Japan, our leaders decided to use these newly developed atomic bombs against Hiroshima an Nagasaki. This is not the place to deal with this history — its issues, geopolitical and moral. There are library full of such analysis. I include this background to give our less history minded readers a sense of the past.

The use of nuclear science and engineering newly discover during the US’s weapons program evolved rapidly. This was a result of initially, of general then President Eisenhower’s, Atoms for Peace program. It was paralleled or closely followed by a shared US and UN sponsored program to support the growth of nuclear energy for electricity generation with the nations of the world. There was at the time a hope for low cost, perhaps not needing to be metered, electricity.

The lead agency for doing so internationally is the International Atomic Energy Agency [IAEA.]

Again, this is beyond the scope of this article, this did not happen. As a result of a combination of accidents, some deadly, some just scary and a growing sense of nucleophobia, especially in the United States and more recently in Germany, nuclear energy became a dirty word. France, China, India do not think so. Apparently neither do Brazil, Russia and Saudi Arabia and it’s neighbors.

For them electricity from highly regulated and proven ‘catastrophe’ safe, nuclear energy remains a reasonable alternative to their options to deal with population growth, middle class aspirations for standard of living related energy shortages, and with energy security.

Even, when the sound and fury and fear factors die down, Japan will have trouble killing off its nuclear program. On the other hand heads should roll for their intuitional and corporative neglect. While the rest of the world made progress in understanding less frequent accident risks such as natural forces (tornedos – tsunamis – earthquakes) the Japanese corporations in bed with their regulators had their heads in the sand. It’s a time honored tradition — They have shamed the nation; perhaps Seppuku would be honorable.

Thorium Fuel Cycle Pro Arguments

Figure 2 - The Thorium Decay Chain

Enough said as background. Despite problems and issues that temporarily shut down nuclear energy programs and projects, almost all the nations of the world are seeking, if not publicly, to make nuclear electricity usually from uranium and a bit from thorium. In that effort, the Thorium Fuel cycle can perhaps play a key longer term role if I understand that ‘energy’ system.It appear to have been well documented, if not yet fully proven to the naysayer’s or for that matter to regulators around the world,Thorium Fuel Cycle is:

  • Safer
  • Cheaper
  • Proliferation Proof,
  • Creates Minimal high-level Waste
  • Eases recycling existing uranium spent fuel, and of course
  • Aiding the effort to become self reliant in Energy for their industry and transpiration needs.

One could now add:

  • Minimizing Greenhouse Gas production
  • Assuring low cost means of purifying sea or recycled and brackish or polluted water for drinking and agricultural purposes.
  • Lowering Transportation and its associated pollution costs

All of these uses have high-energy demands, usually in the form of inexpensive, reliable, safe electricity

For balance, most of the cons of using a Thorium Fuel Cycle have been specifically leveled the Liquid-fluoride thorium reactor (LFTR) or the to early for it’s time (funding) Pebble Bed reactors.

Therefore I cover both positive and negative aspects of these specific solutions to using a thorium-based thorium, in the section below. Had Pebble Bed not happened in parallel to our recent economic meltdown, it might also have been an alterative.

Future Potential Path(s) Forward


  • Focus on spent fuel recycling by proven available chemical processing to recover uranium/plutonium for reuse, while minimizing waste and proliferation risks.
  • Progress with Advanced Reactor Design that initially creates intrinsically safe and ultimately inherently safe nuclear energy generation facilities.
  • Make significant International Progress with controlling the various aspects of the fuel cycle (mining though either waste disposal or reuse, to minimize costs to present and future generation, and of course maximize safety.
  • Expedite designing, testing and deploying alternate fuel cycles that avoid the problems caused by our use of uranium or uranium-plutonium fuel  [MOX] to generate electricity.

That’s where Thorium comes into play. In the section that follows I share the pros and cost of developing and ultimately relying on a Thorium based electrical generation cycle for our electrical needs.

The information below, shared at a summary level, described the myriads of pros & cons in slowly switching to a thorium based fuel cycle. These of course have been heavily discussed in both the scientific-engineering literature including the Internet, and on pro-and-con blogs on the issue. Of course adoption, all thing being equal, will likely happened faster in India, and China, … than in the US.

Unfortunately for clean energy advances which include energy independence and closed cycle nuclear power, since we seem to be a ‘fourth world’ (Doc’s New Label) nation with respect to tackling major global problems such as energy independence, climate change, and low-cost abundant safe energy to boot strap our economy and stamp out poverty.

Low cost sustainable energy will play an important role in economic development, especially approaching 2050 or after. India and China are planning very ambitious programs of nuclear power development. Both countries are planning rapid deployment of significant numbers of traditional Light Water and Heavy Water power reactors, while projecting the further development both Fast Liquid Metal Reactors [FLMR]] and Thorium cycle breeder reactors. (Barton I)

More below about thorium based aspects of these reactors types.


Liquid-fluoride thorium reactor (LFTR) Pros)

  • From the nuclear physics standpoint, they are potentially, passively safe,
  • Past and present designs, and demonstration plants show that they are mechanically simple
  • These reactor types can be quite compact in size allowing them to used in the manner projected for other modular nuclear reactors or small stand alone factory built rechargeable battery style nuclear reactors/power generator systems.
  • They can in principal be deployed virtually anywhere and protected more ealy han large reactor facilities.
  • In preparing to build LFTRs we will recover valuable medical radioisotopes that could provide early financial return.
  • Operating LFTRs will generate electricity, desalinated water, and generate valuable radioisotopes for NASA and the medical sector where ever it is needed, requiring minimal expensive complex grid systems.
  • The possibility of utilizing a very abundant resource which has hitherto been of so little interest that its abundance has never been quantified properly seems worth investigating fully.
  • The production of power that creates fewer long-lived transuranic elements in the waste.
  • They, based on their nuclear physics, produce significantly reduced radioactive wastes.
  • Although I could not document this statement, I believe (yep the belief word) that the amount of radiation spread if battle hardened reactor is hit, would be about the same magnitude of the spent uranium ammunition were spreading now. If a war situation used nuclear weapons – shells – missiles or bombs…all bets are off. You are dead, end the environment doesn’t master. Gaia will recover in a millennia or two.


  • At the current state of knowledge, they have a high cost for fuel fabrication [e.g., due to the presence of 233-Uranium]
  • There are similar problems in recycling thorium itself due to highly radioactive Th-228 (an alpha emitter with two-year half life) is present.
  • There is some concern over weapons proliferation risk of U-233 (if it could be separated on its own), although many designs such as the Russia’s Radkowsky Thorium Reactor addresses this concern. There appear to be safe-cost effective solution to this issue.
  • The technical problems (not yet satisfactorily solved) in reprocessing solid fuels. However, with some designs, in particular the molten salt reactor (MSR), these problems are likely to largely disappear.

Much development work is still required before the thorium fuel cycle can be commercialized This is being done in India and China, The effort required seems unlikely while (or where) abundant uranium is available. In this respect, recent international moves to bring India into the ambit of international trade might or may not result in the country ceasing to persist with the thorium cycle, as it now has ready access to traded uranium and conventional reactor designs

Nevertheless despite the negative aspects that would limit, universally, switching to a thorium fuel cycle, the thorium fuel cycle, with its potential for breeding fuel without the need for fast neutron reactors, holds considerable potential in the long-term. It is a significant factor in the long-term sustainability of nuclear energy.

Gen IV reactor History and Safety Features

These have been universally claimed to be passively safe; that is, they remove the need for redundant, active safety systems. This is in part due to obviating the need for electro-mechanical safety-fail safe feature and any part for human action – The nuclear physics does the job. This is a result of the reactor is design allowing it to both safely handle high temperatures {No melt-down scenario.} The reactor can cool itself by natural circulation and still survive in accident scenarios, which may raise the temperature of the reactor to 1,600 °C.

LFTR type reactors will offer safe, sustainable and efficient nuclear power at a potentially low cost. LFTR and Pebble-bed reactors can also theoretically power vehicles. Why, they would be fail-crash safe, and there is no need for a heavy pressure vessel for containment. Furthermore, the pebble bed heats gas that could directly drive a lightweight gas turbine.

The use of the advanced thorium cycle in a fusion-fission hybrid could potentially bypass the stage of designing and building fourth generation breeder reactors in that the energy multiplication in the fission part allows the satisfaction (achievement) of energy breakeven point and the in magnetic and inertial fusion reactor designs. I have not discussed this somewhat still academic alternative lack of time,

Historically, in the United States, the thorium-fission fuel cycle, which I have not discussed for was investigated over the period 1950-1976 both in the federally funded Molten Salt Breeder 1976 in the Molten Salt Breeder Reactor Studies (MSBR) at the Oak Ridge National Laboratory Reactor (MSBR) at the Oak Ridge National Laboratory (ORNL) as well as in the pilot (ORNL) as well as in the pilot Shippingport fission reactor fission reactor plant.

It has also been used in the High Temperature Gas Cooled Reactor (HTGR) in a pebble bed and a prismatic moderator Reactor (HTGR) in a pebble bed and a prismatic moderator and fuel configurations. General Atomics Corporation (GA) did a large amount of documented-peer review-published work, which the US has ignored but not so the rest of the world.

The General Atomics (GA) Company built two prototype thorium reactors over the1960-1970’s period. The first was a 40 MWeMWe prototype at Peach Bottom, Pennsylvania operated by Philadelphia Electric. The second a 330 MWeMWe at Fort St. Vrain for the Public service of Colorado which operated between 1971 and 1975.

It now appears that the effort to building a Pebble Bed reactor [PBMR ] that was planned in South Africa failed because of lack of Investors/customers, rather then the albeit, large technical and regulatory challenge.

Figure 4. Molten Salt Reactor


Because India was outside the Nuclear Non-Proliferation Treaty due to its weapons program, it was for 34 years largely excluded from trade in nuclear plant components or materials that had hampered its development of civil nuclear energy until 2009. Due to these trade bans and barriers, and the lack of indigenous sources of uranium, India has uniquely been developing a nuclear fuel cycle to exploit its reserves of thorium.

Indeed its expertise has made it the premier source of potential thorium fuel cycle expertise, technology and soon workable-licensable reactor designs. Will building thorium based reactor systems come next?

The Molten Salt Reactor [MSR]

The MSR is an advanced breeder concept, in which the coolant is a molten salt, usually a fluoride salt mixture. This is thermally quite hot, but not under pressure, and does not boil below about 1400°C. The higher temperatures enhance the efficiency of energy generation.

Much of this research has focused on lithium and beryllium additions to the salt mixture to enhance safety. The fuel can be dissolved enriched uranium, thorium or U-233 as fluoride salts. Recent international discussion has been focused on the Liquid Fluoride Thorium Reactor, utilizing U-233 which has been bred in a liquid thorium salt blanket and continuously removed to be added to the core.

The MSR concept and design was studied in depth in the 1960s, and is now being revived because of the availability of advanced technology for the temperature-radiation resistant materials and components. There is now renewed interest in the MSR concept in China, perhaps in Japan, Russia, France and even in the USA, and one of the six Generation IV designs selected for further development by DOE’s advanced reactor program is the MSR.

The Anti-MSR View — In his 2009 article, my colleague Arjun Makhijani, entitled Thorium Fuel: No Panacea for Nuclear Power reiterates the widely published concerns about with implementing a commercial thorium fuel cycle. I agree with the listing of problems, so dies the rest of the nuclear engineering community both engineering and commercial.

I do ask, Arjun, what’s new other then trying to involve the public in another nucleophobic red herring. This is an IEER fault that I can seldom find in studies by the staff of the Union of Concerned Scientists who’s work on nuclear and other energy issues I also follow.



I leave it to the reader, especially the scientist, engineers, economists and science-educated politicians to think about this. I for one would rather pay a short term penalty (cost) for a safer cost effective, proliferation resistant fuel cycle that released except in mining, no green house gases, than the alternatives and comes closer to solving the HLW disposal problem than to throw that valuable asset away.

If wishes were horses (beggars would ride)and I could perhaps:

  • Convince the City of Richland (WA) and Oak Ridge (TN) to set up a municipal ‘battery reactor’ – Ups, NRC is mostly ignoring the licensing of this reactor, and will doubtless prevent us importing them from the UK.
  • If I were not risk adverse, I could invest heavily in thorium mines. However, by the time that licensing anywhere in the world occurs, these ores would become as inflated as gold, palladium or rare earth element ores are now.
  • Buy a real stake (ownership) of the iron and uranium mines that underground repositories create.

I would seriously consider investing my children’s-grandchildren’s future inheritances – what’s left after my wife and I pass on, or at least half of that amount in such a “certified and licensed’ and default insured ventures.

A Final Thought
— Over the many years I’ve know him, I’ve been troubled by my colleague Arjun Makhijani ongoing finding of problems in nuclear and other energy areas that for the most part can be dealt with minor tuning of the design of a project. Most of which has nuclear concerns when reviewed 3-5 years later, have been proven to be technical challenges rather that fatal flaws or perhaps unconventional red herrings. WIIFT anyone?



The Thorium Fuel Cycle, Wikipedia, 2011

All About Thorium, The World Nuclear Association, March 2011.

Thorium Costs, site; Undated

Nuclear Power in India, The World Nuclear Association, October 2011

The Fusion Fission Hybrid Thorium Fuel Cycle Alternative <A Slide Presentation, Feb 2010>. University of Illinois.

Thorium Fission and Fission-Fusion Fuel Cycle, Nuclear Power – Deployment, Operation and Sustainability, by Magdi Ragheb (2011), Pavel Tsvetkov (Ed.), ISBN: 978-953-307-474-0, InTech

Thorium Fuel: No Panacea for Nuclear Power, By Arjun Makhijani and Michele Boyd, dated for the Physicians for Social Responsibility and the Institute for Energy and Environmental Research [IEER.]  

Safeguards Approaches for Fast Breeder Reactors and Associated Fuel Cycle Facilities, Nuclear Security Science Policy Institure, 2010   

The Thorium Fueled Molten Salt Reactor News [MSR] Blog

Nuclear Batteries (e.g., Small Nuclear Reactors) By Eben Harrell Monday, Feb. 28, 2011, Time Magazine.,9171,2050039,00.html/

Pebble Bed Reactor — Wikipedia 2011.

Uranium-233 {formed in Thorium Reactors } – Wikipedia. 2011.

Sidebar Notes

Copyright Notice: Product and company names and logos in this review may be registered trademarks of their respective companies.

Some of the articles cited or quoted in this column are copyright protected – their use is both acknowledged and is limited to educational related purposes, which this column provides.

The author considers, as do many experts, Wikipedia a reliable and accessible site for technical information, provided that the reference cited in the Wikipedia article meets the following standard.

My Standards for References Checks Are the references provided essentially complete or representative of the literature, and relevant?  Do they include both precedent and present work, including any referenced disagreement with any of the article author’s assumptions, methods or views?In addition I always try to glean WIIFT <what’s in it for them?> WIIFT is a neutral characteristic that sets the authors paradigm, some the reader needs to be aware of. It’s like who actually sponsors research, a political add, or ant means of trying to sway you viewpoint – OKAY enough preaching.

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