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Plentiful Energy – The book that tells the story of the Integral Fast Reactor

Yesterday the hard copy of the book “Plentiful Energy — The story of the Integral Fast Reactor” (CreateSpace, Dec 2011, 404 pages) arrived in the post. It is wonderful to see it in print, and now available for all to enjoy and absorb. I was honoured to play a small part in its realisation.

The subtitle of the book is “The complex history of a simple reactor technology, with emphasis on its scientific basis for non-specialists”. Written by the two leading engineers and Argonne National Laboratory Associate Directors behind the integral fast reactor, Dr. Charles E. Till and Dr. Yoon Il Chang, it is a landmark in the sustainable energy literature.

The first paragraph of the Acknowledgements explain the authors’ motivation for writing the book:

In beginning this book we were thinking of a volume on fast reactor technology in general to be done in a manner suited to the more technically inclined of the general public. There had been advances in this technology that had not been adequately covered in the literature of the time, we didn’t think, and we felt that a book on this area of nuclear technology could play a useful role. However, at about this time the enthusiastic advocacy of the IFR in the writings of Tom Blees, Steve Kirsch, Terry Robinson, Joe Shuster, Barry Brook and Jim Hansen began to appear.

In books and articles they outlined the merits of the Integral Fast Reactor and advocated its urgent deployment. Written by these highly technically literate non-specialists in the technology, they provided a general understanding of the IFR and what its implications for energy supplies would be for the future. And they did this admirably, describing accurately and vividly the capabilities of the IFR and the reasons for urgency in its deployment. They could only touch on the technology underlying it, however, and the why and how of the technology that caused it to work as it did, and the influence of the history of its development on the development itself, were obvious to us as being very important too. These things then became the focus of our efforts in this book…

After visiting Chicago and Idaho Falls in 2009/2010, talking to Yoon and Chuck, visiting the EBR-II site, and really getting immersed in the background to the technology, I was delighted to assist in the production of this book by reading and doing a technical edit on the entire draft manuscript — and so I think I can claim to be the first person to have read it all, other than the authors!

More about the book is given at its CreateSpace publishing page, and you can purchase it at (currently for $US 18). Obviously, I thoroughly recommend that all BNC readers get a copy.

The Integral Fast Reactor (IFR) is a fast reactor system developed at Argonne National Laboratory in the decade 1984 to 1994. The IFR project developed the technology for a complete system; the reactor, the entire fuel cycle and the waste management technologies were all included in the development program. The reactor concept had important features and characteristics that were completely new and fuel cycle and waste management technologies that were entirely new developments. The reactor is a “fast” reactor – that is, the chain reaction is maintained by “fast” neutrons with high energy – which produces its own fuel. The IFR reactor and associated fuel cycle is a closed system. Electrical power is generated, new fissile fuel is produced to replace the fuel burned, its used fuel is processed for recycling by pyroprocessing – a new development – and waste is put in final form for disposal. All this is done on one self-sufficient site.

The scale and duration of the project and its funding made it the largest nuclear energy R and D program of its day. Its purpose was the development of a long term massive new energy source, capable of meeting the nation’s electrical energy needs in any amount, and for as long as it is needed, forever, if necessary. Safety, non-proliferation and waste toxicity properties were improved as well, these three the characteristics most commonly cited in opposition to nuclear power.

Development proceeded from success to success. Most of the development had been done when the program was abruptly cancelled by the newly elected Clinton Administration. In his 1994 State of the Union address the president stated that “unnecessary programs in advanced reactor development will be terminated.” The IFR was that program.

This book gives the real story of the IFR, written by the two nuclear scientists who were most deeply involved in its conception, the development of its R and D program, and its management.

Between the scientific and engineering papers and reports, and books on the IFR, and the non-technical and often impassioned dialogue that continues to this day on fast reactor technology, we felt there is room for a volume that, while accurate technically, is written in a manner accessible to the non-specialist and even to the non-technical reader who simply wants to know what this technology is.

The book is both comprehensive in detail and at the same time very readable, telling the personal as well as technical details of the IFR development and the rationale behind the choices made. It includes chapters on:

  • The Argonne Experience and the foundation of the IFR programme (Ch 1-3; allowing readers to get a good feel for the excitement, uncertainty and missteps that occurred in reactor development in the early years of the Lab)
  • A review of the current energy crisis (Ch 4)
  • The basis of choices for the IFR technology (Ch 5; fuel, coolant, reactor configuration, spent fuel processing)
  • The special characteristics of metal fuel (Ch 6)
  • Safety advantages of the IFR systems design (Ch 7)
  • A huge amount of detail on the pyroprocess and electrorefining (Ch 8-9 and Appendix, both for initial preparation of spent light water reactor oxide fuel [Ch 10], and the subsequent multiple recycles of IFR metal fuel)
  • Implications of the technology for waste management and radioactive lifespan (Ch 11)
  • Non-proliferation aspects of the IFR fuel cycle (Ch 12), and
  • A very interesting analysis on the economics of fast reactors in comparison to today’s LWR technology (Ch 13).

For those energy-policy buffs who are focused predominantly on what it all means for the future of abundant low-carbon energy, you could do worse than to jump straight to Chapter 14, “IFR design options, optimum deployment and the next step forward”. The valuable overeview includes a description of what an IFR reactor site would look like, the rationale for sodium coolant over alternatives, the basic physics of fissile fuel breeding, the principles underpinning the reactor design choices, a brief history of fast reactor experience worldwide, some projections on future deployment scenarios, and thoughts on the path forward…

Look, if you are seriously concerned about the future of energy in a carbon-constrained world, I’d argue that you owe it to yourself to read Till and Chang’s book and understand its fundamentals. Also, please pass it around to your friends, colleagues, family, politician — whoever you think matters.

People don’t need to read all the details contained within this to appreciate how robust the science and engineering behind the IFR is, and why it is so critical that this technology is given its chance (but the details are there, if you want them). Read alongside Tom Blees’ Prescription for the Planet, it is clear from ‘Plentiful Energy‘ that a sustainable and prosperous future for humanity and the biosphere is not only possible, but really is within our reach.


By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

60 replies on “Plentiful Energy – The book that tells the story of the Integral Fast Reactor”

I’ve got to show my ignorance. Is the IFR different from a fast-breeder?

Whatever, both monju and super-phénix were sodium cooled, and had very poor operational histories.

Sodium does have an image problem which is easily exploited by journalists: remember the physics master throwing a bit onto a tub of water? Makes much better tv than boring old experts mouthing off.

But in fact, when there was a sodium leak at monju, nobody seems to have noticed for some time. In practice a coating of insoluble salts seems to have formed over it and stopped any further reaction. But the pictures in the press looked a real mess to the uninitiated.


Peter Ottensmeyer’s review of the both is worth reproducing here. Peter is a scientist and member of the IFRG discussion group:

Plentiful Energy describes, in plain language, the record of an exceptionally efficient nuclear-waste-burning power reactor facility of tomorrow that was built yesterday (1964), was proven, was operated flawlessly for 30 years, and was then shut down by Congress. It is a personal tale by the authors, Charles Till and Yoon Chang, who were instrumental in the scientific success of this nuclear plant at the Argonne National Laboratories in Idaho. Their pride speaks volumes for this American scientific accomplishment and their agony is palpable in their account of the politics that stopped the most important advance in safe nuclear physics and engineering, with safety levels that would have avoided the consequences of Fukushima Daiichi, of Three-Mile-Island and of Chernobyl.

The book, sprinkled copiously with why’s and wherefore’s and their answers, is intended for the non-specialist and for the non-technical reader. It meets this goal admirably, in that the neophyte will enjoy the very human aspects of the science while wanting to skim over some of the scientific details, whereas the more expert in nuclear matters would want more technical details than are given. The latter can dig into the numerous references. All in all it is a very readable educational book about a most important chapter in American scientific history. Nuclear proponents might well rejoice in the potential outlined and despair in the potential foregone. Antinuclear advocates might want to reconsider their stance in light of the potential of eliminating existing nuclear fuel waste. Politicians may shake their heads at the decisions of their predecessors in light of current nuclear waste policy difficulties. Most of all it is a thought-provoking read.

Of the fourteen chapters in the book the first four are devoted to the human elements of the science, the people, the interactions and the relationship of nuclear energy to other energy sources. Only then are we introduced to the thinking that led to the choices of the specific power plant design.

The reactor facility that was chosen incorporated only two major components that together constituted the IFR, the Integral Fast Reactor facility. The first was a sodium-cooled fast-neutron reactor, the metal-fueled EBR-II, capable at that time already of consuming in one pass 20% of nuclear uranium fuel or of used nuclear fuel waste that includes long-lived plutonium, americium, curium, etc. No power reactor can claim this, even today, where all water-cooled reactors consume less than 1% of the mined uranium. Those 20% uranium or other heavy atoms are turned into smaller atoms whose radioactivity decays to background levels in two to three hundred years as opposed to the several hundred thousand years for the original plutoniums. The second component was a pyroprocessor, an electrorefiner operating at high temperature in a molten salt bath, which separated the smaller atoms from the remaining 80% uranium and other heavy atoms. These heavy atoms, still being fuel, could be topped up with 20% used nuclear fuel waste from other reactors or depleted uranium from reprocessing plants, and cycled back into the reactor for further rounds of 20% utilization. Thus in five cycles one complete reactor-full of fuel or of currently stored used nuclear fuel waste would be completely consumed.

The authors make it clear that this complete 100% utilization of nuclear fuel from whatever existing source would increase or extend the energy from nuclear power reactors about 100-fold over current fuel consumption levels. This is carbon-free power for electricity or for use as industrial and private heat available for a very long time, centuries, while using up currently stored nuclear fuel waste in the process. Just as clear is the message that the long-term radioactive burden of that waste is reduced by a factor of 1000 to 100,000 as it is consumed, depending on what level is used as a background comparison. There would be no highly radioactive long-lived heavy atoms left at all above background levels. Likewise, after 300 years, even strontium-90 is gone and so is cesium-137, the most worrisome remaining radioactive isotopes among the small atom products.

The book was written after the Fukushima Daiichi catastrophe in Japan. Therefore a complete chapter, Chapter 7, is devoted to a discussion of safety of the EBR-II reactor. Detailed characteristics are described for continual non-power-requiring removal of decay heat from the reactor core (the bane of the Fukushima Daiichi and of the Three-Mile-Island reactors), and for reactor shut down without human or automated intervention under conditions of no cooling for the reactor core (the cause of the Chernobyl disaster). The EBR-II reactor at full power was tested under these rather severe conditions in 1986 and passed easily even with deliberately inactivated control rods. Its safety features are a proven fact, not calculated probabilities. Thus this fast-neutron reactor, operating in the U.S.A. from 1964 to 1994, would have avoided the sequellae of all three major nuclear happenings.

The book is well worth the read. I could not put it down until I had read it twice.


peterc, think of a fast reactor as the general case, and the IFR as a specific systems design with many unique features that were not used in previous fast reactors like Monju and Superphenix — metal fuel with sodium bond, pool reactor design, pyroprocessing etc. Basically, the IFR is the fast reactor done right.



The IFR is a fast breeder reactor. Specifically, it’s a Liquid Metal Fast Breeder Reactor using sodium coolant and metal fuel with an integral reprocessing plant using pyroprocessing attached to the reactor unit. Super-Phénix and Monju used oxide fuel, which isn’t as easy to reprocess as metal fuel.


I’m currently reading Prescription for the Planet, and just ordered Plentiful Energy. Thanks for the heads up.
@unclepete: It’s too bad that neither of these books seem to be for the Kindle (which is a great device otherwise).


Thoruim fueled nuclear seems save although the development is more distant. Is it really safer and possible to develop and use?


A couple of questions;

(1) Why haven’t other countries which pursued fast reactors until relatively recently picked up (or reverse-engineered) the IFR design as an alternative to the clearly unsuccessful approaches they’ve followed?

(2) Supposing the US Congress reversed its position, what would be a plausible time scale for developing and deploying the IFR?


John Quiggin, it would take a lot of space to answer those questions fully. Very briefly, for (1), some commercial “generation IV” units have been operated (such as the Phenix fast reactor in France and the BN-350 and BN-600 in Russia) but there has been limited interest in commercial development. This is largely because uranium is still plentiful and cheap, and the pressurized water reactor technology was heavily invested in early in the commercial years of nuclear power and has become the default mainstay. Historically, there has been insufficient incentive to invest in this “leap” technology, despite its advantages. For (2), it depends on how urgent the requirement was deemed – in principle, the GEH S-SPRISM is ready now, and could be operating within 5 years.



(1) I don’t think it’s clear that the problem is with other fast reactor technologies or that none of them have been successful. For example, the Russian BN-600 has had a good operating history.

In any case, other nations that are committed to nuclear energy (e.g. France, Japan, Russia, China, India, etc.) have indigenous fast reactor programs that incorporate many elements of the IFR design. I think the main differences between the various fast reactor plans are metal vs. oxide fuel, small vs. large reactor, and on-site vs. off-site reprocessing. There are advantages and disadvantages to each of these options, and the optimal choices may be country-specific. For example, countries with large investments in aqueous reprocessing seem to prefer oxide fuels with off-site reprocessing.

(2) More than a decade, probably two, at least in the US. The NRC licensing process is still light water reactor-specific, and in general the further a new technology is away from the norm, the slower the licensing process is. This is why TerraPower doesn’t plan to build the first units in the US.


Re:- Thorium. I hope this doesn’t turn into another LFTR vs IFR argument, but to try to answer the questions:-
Molten salt thorium reactor development got cancelled earlier than IFR development. Only the first small scale prototype got bult and operated, the 2nd stage, approximately equivalent to EBR II in the IFR development story, was designed but exists only on paper. There appears to be no reason to think it would not have worked, and recent studies have come up with several design improvements and variations, but it has not been proven to the level that the IFR has. Some of the pyroprocessing and waste handling techniques developed for the IFR could be borrowed for thorium molten salt reactors, but it would probably still take ten years of work, plus ~$1 bn to build a scaled down prototype, to get to the point that the IFR is now at. Some R&D continues, so that gap is slowly closing, but at much less than 1 yr/yr as funding is so small.

Safety – both MSRs and IFRs have inherent passive safety that makes them safer than existing reactors, that are already safer than coal plants if you account properly for all the health effects from breathing coal smoke spread accross all the billions exposed to it. MSRs don’t have to deal with the fire hazards of sodium coolant. It is the contention of MSR advocates (like me) that it is easier to achieve the required safety standards in an inherently non-reactive system, and that this will help MSRs to be cheaper than IFRs in the long run.

Pros & Cons – MSRs can operate at higher temperatures than IFRs, which improves electrical generation efficiency and opens up some markets for large scale industrial heat and hydrogen production by thermochemical routes, but for baseload electricity applications this advantage probably is not that great.
MSRs need less fissile inventory per unit of power output than IFRs, by a factor of about 5, so for a given quantity of mined uranium or recovered spent fuel from existing reactors, far more MSRs can be started up. On the other hand IFRs can rapidly breed more fuel for starting further IFRs, doubling the size of the fleet every 10? (check the book…) years. MSRs breed only slowly, doubling in 40 years, or hardly at all for recent simplified designs.


Luke, if you don’t want to turn into a debate, then don’t. This entry should be respected as it’s given, about first, the book itself, and then the IFR. LFTR/MSRs need not be brought up at all.



Now that the book is published, can you give us an idea of breeding ratios that can be achieved in an IFR (which you were not able to state specifically a few months ago)?


Even if the IFR works as planned there is the matter of the timeline. Say its first unit comes online in 2030 and the technology starts to have a serious worldwide impact by 2040, what is the carbon load in the atmosphere at that point? If you call it wrong then you have to live or die with the fact there was a lot of energy and expense that was perhaps diverted from solutions that were shorter term and better aimed.


In the Till & Chang book, there is a lot of detailed discussion on breeding rates, and what determines it (eta minus losses). Table 14-2 shows an example with a BR of 1.33, and Table 14-6 shows an example with metal fuel, optimised for breeding, with a BR = 1.627. Given generous assumptions, a BR of 1.5 in an IFR is certainly achievable.


RE: IFR, MSR & thorium.
I don’t see any conflict as there are groups / countries around the world pursuing each of these. A country’s natural resources (e.g. thorium in India), history with nuclear power, research capacity, scale-factors, foreign-oil/coal/gas dependancy, etc. will lead them to prefer one over the others. That’s fine. All can ‘win’ market. All can help us ‘win’ against fossil fuels. The more viable nuclear options we have, the better for the world.

This book, by providing a reasoned argument in favour of IFR does us all a great service in terms of informed public awareness of inherently-safe nuclear power. We should celebrate that and provide it support – , regardless of which nuclear-technology paths we prefer. The first to go ahead will have a tough enough battle even with all our support. Every win will help clear the way for other options. On the other hand, arguments from within the pro-nuclear camp about whether MSR, IFR or Thorium is ‘better’ only help to serve our common opponents, who will divide and conquer, delaying all paths to abundant de-carbonized power.

It certainly appears IFR has advantages in R&D and operational history, especially with full fuel cycle management, which may well get it to market sooner. If so, that’s great. The other technologies can and will follow.

I’ve ordered both books.


Happy New Year to all.
Barry, thanks for the book tip, I’ve just ordered it.

I have a question about separating fission products from spent fuel
(IFR or LWR or liquid fuel salt) in a proliferation resistant way.
Has anyone ever tried converting a mass of spent fuel to a plasma with a high enough temperature that the elements are monatomic and ionized then accelerating the plasma over a magnetic field such that the trajectory of lighter elements (fission products) are deflected much more than heavy elements (actinides)?

This is basically a very crude mass spectrometer since FP’s would be about half the mass of the actinides. For a 1GWe nuke, about 3kg of uranium would be fissioned per day so the mass flow rate does
not seem to be very high and the actinides would not be separated.

Just curious as to wether something like this has been tried. I’m sure there are many practical problems to this approach.


OK ordered it but disappointed that no Kindle….but that’s OK since I am sure that just costs more for the authors….so no IFR book on the beach in Baja, Mexico this weekend……but perhaps as a reward for getting back alive!!


@Dino Rosati

Yes, mass spectrometry does indeed separate different masses, however the mass flux would be tiny, of the order of millionths to perhaps thousandths of a mole per second. The energies of the ions in an MS are indeed very high, but they are accelerated and thus monoenergetic, not thermalised, as a plasma would be. The suggested system would be hard put to remove the thermal energy of a plasma before trimming the beam back to a mono energetic state, so I think the design would settle for volatile molecules, rather than a monatomic plasma. Volatile molecules ex-fuel would have different numbers of plus and minus charges too, more than the mass discrimination between fission product and heavy metal. The ingenious chemistry necessary to make each of the elements volatile would hardly be immune from attempts at proliferation either.

Magnetic separation was used in the Manhattan project. According to Wikipedia : “Magnetic separation was later abandoned in favor of the more complicated, but more effective, gaseous diffusion method”. The industry has since moved on to centrifuge separation, which is more efficient still.

However I share Dino’s curiosity as to how the IFR separates the mess of trans-actinides from the mess of fission products. Does anyone know just how cleanly pyroprocessing separates them? I find it hard to believe that there is some voltage above which all heavy isotopes plate out (but no fission products) and below which nothing plates out at all.


Till and Chang indicate in PE that initially the pyroprocess facility (fuel conditioning facility) was not designed for severe events like earthquake, high winds, etc. Improvements were subsequently made.(173-4)

In light of Fukushima, I’m assuming station blackout issues would be addressed since, for example, the “process control and accountability system” must keep track of things like “criticality safety limits.”

I assume meeting these sbo requirements would not be difficult. are there any details to report on sbo issues?


Here is a note that Len Koch sent around, which is interesting and related closely to the above post:

I continue to be confused and concerned about the apparent “IFR SRATEGY “ to minimize (or ignore) the established history of this concept. It was CONCEIVED in the 1940s by Enrico Fermi and his colleagues. I learned the details in late 1948 when Dr. Fermi presented a Seminar at which he described his vision of nuclear power for the future, with the potential of providing a new energy source for the foreseeable future.

He acknowledged that it had already been demonstrated that the energy contained in the fissionable rare U-235 isotope could be extracted, but its scarcity essentially eliminated it as a long term energy source. He then described his vision of nuclear power which involved extracting the energy from the abundant “ non-fissionable” U-238 isotope.(the 99.3% of natural uranium).

He discussed what needed to be done to establish the feasibility of this concept. He explained that a two step process was required because “non-fissionable U-238” would first be converted to “fissionable Pu-239” and then the Pu would be fissioned. He had concluded that this could be achieved in the fast reactor they had conceived, and in fact such a reactor could produce more plutonium than it would consume. IT COULD “BREED” PLUTONIUM! Fermi cautioned that this concept would also require that it would be necessary to recycle this fuel on a continuing basis to consume the U-238, that it was not a “once thru” option.

He then described an experiment being developed to demonstrate the feasibility of this breeding concept. Needless to say, I was enthralled to hear his description of the experiment I WAS WORKING ON! It became known as the Experimental Breeder Reactor (later it became EBR-I to differentiate it from EBR-II). This reactor, fueled with U-235 as a substitute for Plutnium (because of availability of technology and material), established the feasibility of the “fast breeder concept”.

Even before the successful operation of EBR-I was accomplished, ANL began planning the development and demonstration of the second requirement of the Fermi concept, fuel recycle. It grew as a “multiple discipline” effort coordinated and directed by the Lab Director, Walter H. Zinn, (who had also directed the EBR-I program). The EBR-I had not addressed the fuel recycle requirement and it became the driving force of this second development effort. Power reactor fuel technology was still very much limited to uranium. The Chemical Engineering Division was developing “pyroprocessing”as a possible technology for fast power reactors. The Metallurgy Division was developing fuel fabrication processes and the Reactor Engineering Division was developing Power Reactor concepts incorporating “power reactor features”(as contrasted to the EBR-I concept which resembled a research reactor).

The EBR-II concept grew out of this multi discipline effort. It turned out to be a very bold, radical approach to Fermi’s concept, but it addressed many problems that persisted with sodium systems, The EBR-II concept was built around the fuel cycle which had been selected. This too required initial work with a Uranium alloy fuel AS PRODUCED BY THE FUEL REPROCESSING CYCLE! The Announcement of the Authorization of EBR-II states (March 3, 1958): “The EBR-2 is an integral nuclear power plant. It includes a complete fuel processing and fabrication facility in addition to the reactor plant, heat transfer systems and steam-electric plant”.

Others, notably France and Great Britain, quickly adopted the basic EBR-II reactor system concept of a submerged (in sodium) reactor and primary system. Phenix in France and PFR in Great Britan. Neither adopted the fuel recycle concept, but received much operational experience. Phenix operated for more than 30 years. Both countries (as well as others) have accumulated much fast reactor experience.

EBR-II began “approach to power” operation in 1964” and operated for about 30 years as an experimental nuclear power plant connected to the grid. It operated on recycled fuel (about 5 complete core loadings) until prohibited by Governmental edict, prohibiting the use of recycled fuel in power reactors. After the prohibition of fuel recycle,“simulated recycled fuel” was manufactured commercially and used, but not recycled. NOTE: in my opinion, this was one of many stupid mistakes that were made in the life of the United States fast reactor development program. We owe Enrico Fermi and his colleagues our deepest apologies!

A few thoughts about the future: I recently read that the DOE has about 700,000 Tons of depleted uranium in storage. I presume that a large part of that material is stored in the typical containers that contain about 14 tons each. In an article I wrote about 10 years ago, I included a photo of a worker checking some of the cylinders containing depleted uranium. A printed note on the photo (which I keep on my desk to retain my perspective ) “Each 14 ton cylinder contains the energy equivalent of about 100 MILLION BARRELS OF OIL”. At 14 tons each, the DOE has about 50,000 of these cylinders in storage, each containing the energy equivalent of 100 million barrels of oil! The rest of the world has more!

Dr. Fermi was right! We have a tremendous source of energy! It is essentially unlimited. And it can be extracted without “burning something and producing CO2”. Will it be used? Certainly! When will it be used? When it is properly evaluated. Probably by others that really need it (everyone now knows what is required).

I believe that China and India may be the most motivated at this time; China because of the need to support its growth in energy demand and India because of growth and the desire to utilize their tremendous inventory of thorium which can substitute for U-238. It is noted that both countries have negotiated with Russia about providing 800 megawatt fast power reactors to them.

I am compelled to raise this discussion because this is not a NEW subject. Fermi and the other PIONEERS in the nuclear power field conceived this real new source of energy more than 60 years ago. It is not new! Much has been learned (but not as much as should have been). This concept was not developed from 1984 to 1994, It was developed from about 1954 to 1994 with much thought preceding it. EBR-II IS THE ONLY “INTEGRAL REACTOR” ever built and operated. It was shutdown, by edict too, in 1994.

I believe that we are performing a disservice to the concept by ignoring the early work. This is not a new, untried concept. It provides another power option with many new characteristics that could be preferable to the existing power plants. If fast reactors are thought to be new and untried they may not be given appropriate consideration. Therefore, I believe that proper recognition of the maturity of this concept will actually add substance to its acceptability.

Leonard Koch


In answer to how pyroprocessing separates the mess of trans-actinides from the mess of fission products, my freshly arrived copy of “Plentiful Energy” explains with a table (A-1 on p 354) ranking the components by their energies of formation of chlorides. These energies are divided by the mass, so they are not quite proportional to electrode potentials, but where the masses are similar the table provides a ranking roughly equivalent to electrode potentials. Here, the relevant actinides do indeed group together, suggesting that they might be separated out as a group by electrolysis.

Of these, uranium is lowest, followed by neptunium, americium, plutonium and then curium, so uranium must plate out first.
The book describes how, in a two-step process, the overwhelming excess of uranium is first drawn off at a steel cathode. As its concentration drops, the voltage is allowed to rise until the higher actinides begin to plate out with it. Then a liquid cadmium cathode is switched in. There, with the uranium concentration already drawn down, the voltage continues to rise so the minor actinides and plutonium plate out with it into the cadmium.

A compound of cadmium and plutonium buffers the ratio of plutonium to uranium in the cadmium melt to rather better than 1:1, sufficiently fissile to be used as seed fuel without further processing after removal and distilling off the cadmium. The uranium drawn off at the steel cathode is returned to the breeder blanket in the next cycle.


Nice summary Roger Clifton, thank you.

It seemed to take forever to come from Amazon but my own copy of Plentiful Energy has now arrived and its a fascinating read. If the authors were agreeable I’d suggest three short extracts would make an excellent set of stand alone posts on BNC, very readable descriptions of the technology and the design choices that were made. These are:

5.2.1 The Fuel Choice: Metal Fuel
5.3 The Coolant Choice
5.4 The Reactor Configuration Choice



Can they go a bit further with the cost estimates. To calculate LCOE we need capital costs, construction duration, expected economic life, fixed O&M costs, variable O&M costs, fuel costs, thermal efficency, auxilliary load %, and expected capacity factor (a conservative estimate for plants in the early stages of a new technology). I expect the fuel costs should include all the costs that are needed to make the the fuel costs for IFR comparable to the Gen III fuel costs ($0.94/GJ in constant 2009-10 A$ according to EPRI (2010)).

Also, what is the basis of the estimates and who did them? Estimates that are done by researchers or advocates for a technology suffer the same credibility issues as estimates made by the wind farm and renewable energy proponents. They lack credibility. Idealy, the estimating would be done by a credible, independent, impartial, firm with the approporate qualifications and experience. EPRI would be one such firm with credibility. Have they, or a similarly respected firm, done anything on estimating the costs for the IFR, or passed comment on the estimates done so far?


I think it is better I post my thoughts on the estimating of the IFR before, rather than after the post. That way, the authors can address my concerns.

My main concern is that no matter what the estimate, it will be very difficult to believe it. Cost estimates for pioneer projects invariable overrun by orders of magnitude. Even more mature technologies over run by large amounts. A few examples com to mind:

The join strike fighter project is continually being delayed and the cost is escalating. We’ve been building new military planes for decades, so why can’t we get the cost and duration estimates reasonable good? If the US can’t get the estimates right for something the they’ve been doing for many decades, how can we believe the estimates for a pioneer IFR plant?

It took 50 years to get from Gen I to Gen III+ nuclear power stations. I don’t know why we should expect to get to a mature Gen IV much faster – unless the economic life of the plants is much shorter. The economic life is significant because the faster the plants are decommissioned and replaced with a newer design the faster will be the learning rate. That is why computers improve rapidly – they have about a 3 to 5 year life expectancy.

So, I’ll take some convincing that any estimate of the cost, construction duration or life expectancy of an IFR will have much credibility.

Does anyone have any figures for the all in cost for the PRISM being offered to the UK?


Peter Lang — The reason that computers improved rapidly was because that was possible and there were many competaters which helped push every one to improve as rapidly as possible. While the various early designs were made obsolente because of high maintenance, etc., for decades computers have lasted for longer than most have wanted to keep the older, much slower units. In my back lab I keep some of those from (gasp!) the previous century which I occasionally use for various testing purposes. Those run adequately albeit much too slow for regular use. Roughly, the computers of this century are adequate for the majority of purposes and anyway, without a substantive change in technology, won’t become noticabbly faster, just physically smaller.

The authors, Till & Chang, give their cost estimates based on their experience in running a small IFR for 30 years. Somewhere, maybe earlier of this thread, thre is a link to the MIT estimate (which I have not read) suggesting that the LCOE for an IFR is slightly higher than for a Gen III+ NPP. Unfortunately thre are still, it seems, some engineering issues regarding pyroprocessing and so the costs of early units may be higher than current estimates. The proper approach is to build a prototype and then improve based on experience. The attempted analogies to computers and the joint strike fighter are, IMO, misleading.


“Bought the book. Initial response is that I’m a little disappointed. I haven’t finished but it seems more a wail about how stupid the authorities were at canceling the project than discussing the pro and cons. More a vehicle ( initially at least) for airing their grievances about their redundancies?
I’m persisting–there is information too”


Frank Holland — Finish the book first; you’ll understand then why the authors advocate the design and what technical problems remain.


While I ordered it as a physical copy I would like to agree with Katy, it would be much preferable in kindle or similar format. The actual printed copy is in a cheap and somewhat akward form-factor I think. Additionally it would be great to be able to access the book through amazons various kindle-apps when you needed a quick reference.


There seems to be a lot of confusion regarding breeder reactors and what they entail. I’ve seen people, even those with strong scientific backgrounds, claim that the only reason to have a breeder reactor is for nuclear weapons production. My own viewpoint is not currently set, as I am one of the confused.

I was further confused by the book Radiation and Reason: The Impact of Science on a Culture of Fear, which in one chapter seemed dead against breeder reactors, but in other chapters praised and supported the concept of fuel recycling.

I’ve ordered the book in hopes of better understanding the concepts and relationships between them. Regardless, I think this is an area that needs more focus, as even those who try to gain an understanding have difficulty in doing so.


I highly recommend this book to anyone who is interested in the future of nuclear power. Especially to those who, like me, previously believed that the promising (but as yet unproven) liquid thorium reactors were our only hope for sustainable and affordable energy. IFR is now on my favorite reactors list, right alongside LFTR and DMSR.

The book does a good job of explaining why the IFR (Integral Fast Reactor) development should be affordable, even though previous US fast reactor efforts costs billions but still ended in program cancellation. It explains why the IFR has much improved safety performance in accident scenarios compared to other sodium cooled reactors like Clinch River Breeder Reactor and SuperPhenix (IFR’s metal fuel melts and is forced out of the core by fission product gas during a severe accident which prevents the explosions which are possible with conventional oxide fuel). And it describes the real-world fast reactor accidents at EBR-I (meltdown and several minor fires), Fermi-I (meltdown), and Monju (major sodium fire).

A big problem that I had with the book was that it needlessly antagonized the mainstream environment movement by singly focusing on the Fermi vision for a plutonium economy. It turns out that unlike LWRs, the IFR (and molten salt fueled reactors) is surprisingly compatible with renewables. The operating temperature facilitates thermal energy storage with large tanks of molten “solar salt”. For locations which are unsuitable for pumped-hydro (i.e. most of the world), thermal energy storage is by far the lowest cost option, and probably always will be. For example, IFRs could be equipped with turbines that throttle between 50 % and 150% of their steady-state output, with the balance of power going to or from storage.

IFRs and molten salt reactors also can support renewables with rapid power throttling (this improves grid stability even when the reactors are run at high capacity factor). Xenon transients make it undesirable to throttle LWRs. An isotope of xenon which is a very strong absorber of thermal neutrons is created in reactors after a few hours of decay of fission products; this is not a problem in steady state, but is problematic with throttling up or down. This is not applicable for the fast neutrons present in the IFR, and in molten salt reactors gaseous xenon is removed within minutes of its formation.

Lastly, renewables use can be facilitated by having large dispatchable loads such as hydrogen synthesis (as feedstock for fertilizer or transportation fuel). IFRs can generate hydrogen with thermo chemical cycles such as the copper chloride cycle (which is also being researched at Argonne labs: ) or using electrolysis. Molten salt reactors are bit more promising in this regard since they can potentially reach the 900C temperatures required for the more efficient (50 % vs. 40 %?) Sulphur-iodine process.

The biggest shortcoming of the book is lack of a good proliferation resistant vision (the ARC-100 product whitepaper describes one fast reactor vision: ). A combined system with IFRs and DMSRs strikes me as much more appealing (DMSR= Denatured Molten Salt Reactor, a near-breeder which runs on thorium and low-enriched uranium, has been called the most proliferation resistant reactor of all: ). The IFR could be used where on-site reprocessing is desired, and the DMSR when off-site reprocessing is preferred (or when higher temperature process heat is needed). But this book makes no comparison to thorium or liquid fuel technology (and no mention of DMSR at all). They don’t even answer the question of why not use a salt as the secondary coolant to avoid the sodium fire risk.

On proliferation, they mostly just engaged in hand-waving. The IFR is not the reactor that most people would choose to export to a non-fuel cycle nation (the fuel is a dirty mix of heavy isotopes, but the breeding blanket can make weapons grade Pu). They only partially resolve my concerns about fuel diversion by sub-national groups: I was worried that the metal fuel could be re-cast into low-yield (fizzle) bombs behind light shielding by operators who didn’t mind a little radiation sickness (the zirconium content of the fuel pushes the density down 26% and the larger reactors can use fuel that’s more than 80% U238, both of which increase the critical mass, making weaponization harder; but they gave no specifics on critical mass). In fuel cycle nations, plants with integrated fuel processing are safer, since the initial fuel load can be diluted with U238 for shipment, and then concentrated in the pyro-processor over a period of weeks or months before fabrication.

Somewhat surprisingly, in the very long section on pyro-processing (which I would have called electro-chemical-refining), they make no mention of processing thorium based blanket material. It seems to me that the IFR could be a great off-site companion for a DMSR. When deployed at two DMSRs per IFR, the IFR could burn all of the TRUs (trans-uranic elements) produced in the DMSRs and breed enough U233 to supply their annual make-up fuel (like the Indian nuclear vision, but with DMSR replacing the HWRs). It could re-enrich the DMSR’s spent uranium without creating HEU or contaminating a centrifuge facility: just blend the recycle U into thorium blankets for the IFR, and then reprocess the blankets when they reach the right U233 content for the DMSR. When DMSRs are fueled with enriched mined uranium, each IFR could maybe burn TRU waste from 5-10 DMSRs, but there is a question about the high neptunium content (15% of TRU), since Np doesn’t respond well to delayed neutrons. They reported on some EBR-II testing with Np-containing fuel, but the Np was diluted 20:1 with Pu (as in LWR waste).

Overall though, it’s a great book which should go a long way to saving a great technology that could otherwise be lost due to lack of publicity.


@Nathan, very nice review. I agree with everything you said except for this:

“Lastly, renewables use can be facilitated by having large dispatchable loads such as hydrogen synthesis”

Large dispatchable loads are more expensive than large steady loads. There are two important effects:

1. capacity factor increases capital costs per unit output
2. transients often reduce efficiency or quality

Capacity factor: Suppose you have a large load facility like an Aluminum smelter or Hydrogen electrolyzer. These cost significant amounts of money to build. If you run the facility 20% of the time (say because excess wind is available a fraction of its 30% CF) then the facility will cost 5 times as much per unit of Aluminum or Hydrogen produced. It would be very significantly cheaper to invest in a facility near a constant, base-load source of power.

Transients: Suppose your large load facility like an Aluminum smelter or Sulphur Iodine cycle Hydrogen production facility operates at high temperature. If you shut it down, you will have to maintain its temperature while it is not operating. This will cost excess power. Also, you won’t maintain the temperature of all components exactly the same in the non-operating condition. Thus you will be experiencing thermal cycles with attendant creep and wear. The plant will also not operate at nominal efficiency until the warmup transient as settled. So there are two costs from cycling the facility: temperature cycle induced wear (typically several thousand dollars per cycle of a large gas turbine power plant) and reduced thermal efficiency or reduced product quality while operating off-nominal during the transient. For large systems, this transient can last an hour or more. If the system is operated for just 20% of a day (5 hrs) and the transient is 1 hr, a very significant fraction of the output might be more expensive or reduced in quality. Again, you’d prefer to locate your facility near a constant source of power.


Nathan and Chris: very good points, thank you for sharing.

On what Chris said, excellent points, I would add that if you go to the bother of a thermal storage system, you might as well buy an extra peaking steam turbine to go with that storage system. You can then use the peaking steam turbine yourself and get into the high value peaking sales market, very reliably, as opposed to using unreliable wind or solar, that would require far bigger thermal reservoirs to achieve the same amount of reliability. In fact their seasonal and multi day variability would put this idea off way outside what is economical, unless you want to burn natural gas during entire seasons.

On the issue of the coolant, I wish they were more fair towards lead as a coolant. It’s really a great coolant with the right design and materials, and is perfectly compatible with steam cycles.

On the issue of proliferation resistance, I’ve always though an IFR with thorium and uranium – a hybrid fuel cycle – is very attractive.

The uranium, being depleted or natural uranium, would be mostly U238. So it would dilute the bred U233 to low enrichment levels. No fissile bombs possible this way. Also there is U232, which is produced from n,2n reactions, that are very strong in the fast spectrum. U232’s gamma radiation spewing daughters make fission or even fizzle bomb production impossible; the would be bomb builders would kill themselves when working with this material in a weapon pitt. However, it poses no added difficulty for the IFR which is automated reprocessing beause of the high Na-24 and fission product radiation.

On the plutonium side, the thorium cycle produces a bunch of Pu238, which puts out lots of sponteneous fission neutrons, and also a lot of heat that would melt any bomb, even a fizzle bomb (cooling with water and oil is obviously out of the question – those are moderators!). Plutonium is pyrophoric so the would be bomb makers would only achieve setting themselves on fire. What’s more, plutonium is more difficult to chemically seperate from thorium than from uranium. In fact it is very difficult and caused even a well funded national lab (ORNL) a lot of headaches when they wanted to make a molten salt reactor. With lots of thorium going with the plutonium, making a bomb is out of the question.

That seems to me a huge amount of inherent proliferation resistance built in. As a bonus, thorium metal fuel has a higher melting point than uranium, and doesn’t change phase until a very high temperature, so less of the zirconium is needed to constitute the fuel.


In 1958-63 I was a reactor operator and supervisor of a university research reactor. There were, of course, many discussions about the future of nuclear technology in our world wide energy market with faculty and the public. One professor of petroleum technology responded to my opinion that reactors would soon supply much of our commercial energy needs by stating that it would never happen; because the consortium of oil producing companies would not tolerate the competition. He was one of their major consultants, understood that they, the banks and insurance companies controlled the world and would so complicate the implementation of nuclear technology that it would never threaten their cash flow. He certainly was able to product the future. Even an orangutan get can clearly see that a Gen IV Type system should have been implemented decades ago. To quote some ancient wise-man “we get too soon old and too late schmardt”. To implement fast or epithermal technology would be safe, cost effective and the best thing for the future of our planet, but don’t hold your breath. Regards, Mike Staehle


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