EDWARDS: Thorium Reactors: Back to the Dream Factory

[Oscar]

EDWARDS: Plutonium and Thorium based reactor concepts prior to 1945.

by Dr. Gordon Edwards

April 23, 2011 1:20 AM

HISTORICAL BACKGROUND: THORIUM IN REACTORS

I have received a number of inquiries about "thorium-fueled" nuclear reactors. In order to provide some context, I have decided to circulate some paragraphs that I wrote in 1990-92 under contract to the Canadian Environmental Advisory Council. These excerpts deal with the early history of nuclear research in Montreal during World War II, conducted at a secret laboratory on the slopes of Mount Royal -- a satellite operation connected to the tripartite (US-UK-Canada) Atomic Bomb Project.

Before the end of the war, nuclear scientists had already foreseen the need to go beyond uranium-235 as a nuclear fuel because natural uranium supplies would run out quickly if thousands of "nuclear boilers" were ever built. This motivated a consideration of "advanced fuel cycles" based on either plutonium (a man-made element produced in a reactor when atoms of uranium-238 are bombarded with neutrons) or uranium-233 (a man-made isotope of uranium produced in a reactor when atoms of thorium-232 are bombarded with neutrons). These are very old ideas.

Those not familiar with the early history of the nuclear age are often fooled into thinking that these old ideas are instead very new. Such is the case with the so-called "thorium-fueled" reactors. Thorium is a naturally occurring radioactive material which is approximately three times as abundant as naturally-occurring uranium.

First and foremost, it must be understood that -- unlike uranium -- thorium can NOT be used as a nuclear fuel. If you loaded only thorium "fuel" into a nuclear reactor and "turned the switch", nothing at all would happen. No energy; no heat, no chain reaction; no steam; no electricity; no nothing.

BUT: when thorium is bombarded with neutrons produced by SOME OTHER nuclear fuel, then a fraction of those thorium atoms are transmuted into atoms of uranium-233 -- an isotope of uranium that is not found in nature. Uranium-233, as it happens, is a powerful nuclear explosive material and can also be used to fuel a nuclear reactor. So, although thorium is not a FISSILE material (it cannot be used directly to fuel a reactor or to make atomic bombs) it is a FERTILE material (it "breeds" uranium-233 which can be used either as fuel for a reactor or as an explosive material for bombs.)

In this respect thorium resembles uranium-238, which is also not fissile and not a nuclear explosive material (unlike uranium-235, which is both of those things). Uranium-238 is not fissile, but it is fertile -- because when atoms of uranium-238 absorb a neutron, they are rapidly transmuted into atoms of plutonium-239: a man-made material which is very fissile and also a very powerful nuclear explosive.

So when one hears talk of "thorium reactors" it is important to realize that this only makes sense in the context of an "advanced fuel cycle" that requires the reprocessing of irradiated uranium fuel before anything else can be done.

Reprocessing irradiated uranium fuel entails dissolving the intensely radioactive fuel bundles in boiling nitric acid and then chemically separating the plutonium (typically less than 1 percent) out of the highly radioactive and corrosive witches' brew of liquid wastes that results. Radioactive gases and vapours are released from the irradiated fuel when this is done, and the leftover liquid wastes contain hundreds of heat-generating radioactive materials that were created inside the reactor. The recovered plutonium (a fissile material which can be used as a nuclear fuel or as a nuclear explosive) must then be blended with thorium to produce a "fissile-fertile" hybrid material that can be used to fuel a nuclear reactor, using plutonium as the fuel and thorium as a fertile material that "breeds" uranium-233. That uranium-233 can later be used as a fuel....

In short: ANY discussion of thorium reactors IMPLIES the reprocessing of irradiated nuclear fuel, and the recovery of plutonium from that irradiated fuel, as a first step. Only when that fact is clearly understood can any further useful discussion take place about the different variations that have been advanced by proponents to implement the "thorium cycle" idea.

Gordon Edwards.

=======================

As promised, here is some historical background:

Excerpts from
http://ccnr.org/ceac_C.html

Health and Environmental Issues Linked to the Nuclear Fuel Chain written by Gordon Edwards Ph.D. for the Canadian Environmental Advisory Council

From Section C: Nuclear Fission.

C.20. Canada's First Nuclear Reactor

Finally, on April 13, 1943, in Washington D.C., the Committee decided that a large-scale pilot plant for plutonium production would be built in Canada using heavy water as a moderator. Materials would be provided by the U.S., but no information would be imparted about the chemistry or biomedical hazards of fission products or plutonium. The Montreal team would have to discover all such information for itself using a few irradiated uranium rods donated from U.S. reactors.

The first necessity was to find a firm to design and build the pilot plant in Canada. The natural choice was Defence Industries Limited (DIL), a crown company involved in munitions manufacture, whose key staff was drawn from CIL. On May 18 the DIL Directors were briefed on the nature of a nuclear chain reaction and the basic requirements for a heavy water moderated reactor.

They were told the reactor could not explode like an atomic bomb because it would use only slow neutrons. It was nevertheless clear that an uncontrolled chain reaction would result in a violent release of energy, possibly scattering fission products over a wide area. On several occasions before the first atomic bomb was tested, it had been suggested that great damage might be done to an enemy by dropping fission products from the air, thereby contaminating food and water supplies and making strategic areas uninhabitable. Any similar contamination occurring by accident, it was pointed out, would have a deplorable effect on the future public relations of CIL.

Mackenzie retorted that CIL would surely not escape blame if DIL refused the contract and some less capable firm did the job. That could be seen as evasion of reponsibility. On May 26, DIL accepted the contract, and the search for a site began. For reasons both of safety and security, it would have to be isolated.

The shores of Georgian Bay, Lake Superior and the La Tuque region of Quebec were considered. Finally, in mid-July, a secluded spot on the Ottawa River was selected. It was two hundred miles northwest of the capital, near the small village of Chalk River. A townsite for employees was chosen at Indian Point a few miles away; the community is now known as "Deep River". Deep River was situated far enough upwind and upriver of the Chalk River research reactors to avoid radioactive fallout.

C.21. The Chalk River Nuclear Complex

Meanwhile, the Montreal group had determined the basic features of the Canadian pilot plant, to be called NRX for "National Research Xperiment". The fuel would consist of 175 rods of uranium metal, each with a thin coating of aluminum. The coating, or "cladding", would protect the metallic fuel against chemical reactions and prevent the escape of fission products. The fuel rods would be suspended in an aluminum tank full of heavy water, surrounded by graphite to "reflect" escaping neutrons back into the tank.

Since NRX would generate more than ten million watts of heat, the fuel would have to be cooled to prevent melting. Reliable shutdown systems would be required to halt the chain reaction abruptly if it began to get out of control. Biological shielding would be needed to protect workers from neutrons during operation. In addition, the gamma radiation from fission products would be so intense that massive shielding would be required to safeguard workers at all times, even when the reactor was shut down.

These safety concerns greatly complicated the design of the plant. The NRX fuel rods were to be housed in double-walled tubes through which ordinary "light" water would be pumped at very high speed to cool the fuel. The tubes had to be thin, so as not to absorb too many neutrons, but strong enough to prevent a loss of coolant. The heavy water moderator would fill all the remaining space in the tank outside these vertical tubes. Between the tubes would be hundreds of adjustable "control rods" made of neutron-absorbing materials. When inserted vertically into the tank, these rods would soak up excess neutrons, slowing down or stopping the reaction.

Structural materials near the core of the reactor would inevitably absorb stray neutrons. Due to the resulting activation (see A.21), all of the internal structures, including the cooling tubes and control rods, would become intensely radioactive. Thus, maintenance could be performed only by remote control or after a lengthy shutdown. Given these complications, it was considered prudent to build a much smaller and simpler reactor -- using the same fuel, moderator and reflector as NRX, but not powerful enough to need cooling and not radioactive enough to prevent workers from approaching it. It was to be called ZEEP for "Zero Energy Experimental Pile". [48]

In late July, Cockcroft sent for Lew Kowarski to take charge of the ZEEP project. A member of the original Paris group, Kowarski brought with him some other members of the Cambridge heavy water team who had chosen to stay in England because of personal difficulties with van Halban. The Canadian government had offered to pay the whole shot, but the final cost estimate was something of a shock. It included NRX, ZEEP, two chemical extraction plants, a huge water purification plant and a maze of labs and offices. It also included an entire planned community at Indian Point (the village of Deep River) complete with hospital, school, shopping centre, recreational hall and administration building.

Ottawa gave its approval for the Chalk River complex on August 19, 1944, five days before the liberation of Paris.

C.22. Advanced Reactor Concepts

There were now about 100 scientists in the Montreal group -- over forty Canadians, an equal number of British, and twelve others -- including five French citizens. During the fall of 1944 and the spring of 1945, while detailed design work for NRX and ZEEP was underway, these scientists also found time for other types of advanced research.

The Americans had suggested that in designing the NRX reactor, provision should be made for thorium rods to be inserted in the graphite reflector. By then it was known that thorium-232 changes into fissile uranium-233 by neutron capture, just as uranium-238 changes into fissile plutonium-239. A new man-made isotope of uranium, U-233 could be used as a nuclear explosive and so was worth investigating.

The British were beginning to plan for the post-war period. Having no heavy water in England, they elected graphite as their moderator of choice. A "graphite group" was formed at Montreal in December, 1944, and by the end of the war all the basic design work had been done for Britain's first experimental reactor at Harwell, called BEPO. The graphite for Britain's first few reactors came from Ontario.

Early in 1945 a "future systems group" was formed at Montreal to brainstorm on other possible reactor designs. Special materials able to resist corrosion, conduct heat and tolerate radiation were sought out. A variety of liquids and gases were investigated for possible use as coolants. In the end, this group anticipated every major conceptual development in reactor design for the next quarter century.

In particular, they perceived that economic deposits of uranium are likely to be rather scarce. Accordingly, if nuclear boilers were to last for more than a few decades as an energy source, they saw a need to "breed" a man-made substitute for uranium-235; either plutonium-239 bred from uranium-238, or uranium-233 bred from thorium-232.

They were thus led to conceive a futuristic type of nuclear reactor, fuelled by highly concentrated ("enriched") fissile material, fissioned by fast neutrons rather than slow ones, and surrounded by a blanket of uranium-238 or thorium-232. In principle, more fissile material can be bred in the blanket -- by neutron capture -- than is consumed in the fuel. This greatly extends the supply of nuclear fuel. Such advanced reactors are called "fast breeder reactors", and the stuff in the blanket is appropriately called "fertile material". Experimental breeders have since been built in the U.S., the U.S.S.R. and France.

C.23. Reprocessing Spent Nuclear Fuel

In July, 1944, the U.S. delivered to Canada a few irradiated rods of uranium (containing plutonium), and of thorium (containing U-233). The Montreal chemists knew little about the U.S. method for seperating plutonium except that it was based on precipitation. The Americans would first dissolve the spent fuel in nitric acid, then chemically convert the dissolved plutonium into a solid which would slowly settle out, leaving fission products and uranium in solution.

Precipitation has one big disadvantage: it can only be done in batches. It is a stop-and-start operation. The Montreal team sought a process that would run continuously, producing a steady stream of plutonium. Over two hundred solvents were studied to find one that would strip plutonium away from the other radioactive materials, creating two liquid fractions which, like oil and water, do not mix. The plutonium-bearing fraction could then be separated mechanically and continuously, and from it the plutonium itself could be extracted at will. Similar concepts applied to the separation of U-233.

The British and French both gained a distinct post-war advantage over the U.S. in reprocessing technology -- the technique of recovering fissile material from spent nuclear fuel -- as a result of their Montreal experiences. That advantage persists to the present day.

[Oscar]

What do you get when you cross an accelerator with a nuclear reactor?

http://www.guardian.co.uk/science/blog/2012/feb/09/
accelerator-nuclear-reactor

Posted by Corrinne Burns Thursday 9 February 2012 12.50 GMT
guardian.co.uk

An abundant source of nuclear energy with no danger of meltdown, and a possible solution to the world's energy crisis

Professor Bob Cywinski is every inch the academic: a wavy-haired, bearded man with a voice like hot coffee poured on a Sunday morning. But he is also a man with a dream: to change the nuclear landscape of the UK.

Conventional nuclear power (fission) is controversial and carries inherent risks, but no other energy source has a chance of securing our energy needs for the future. Nuclear fusion – for many scientists the ultimate goal of energy production – is still a long way off.

Cywinski is part of a team of scientists who are working towards an entirely new type of nuclear reactor: one that could be operated safely and without generating long-lived radioactive waste. This new reactor could even consume the toxic waste generated by conventional nuclear reactors, removing it from the ecosphere.

It's called the Accelerator-Driven Subcritical Reactor (ADSR), or Energy Amplifier, and in a recent lecture hosted by the Leicester Literary and Philosophical Society, Cywinski outlined his vision of an ADSR-powered future.

The concept was first proposed in 1993 by Nobel prizewinning physicist Carlo Rubbia. The basic idea – and what distinguishes it from all other nuclear reactors – is the coupling of a particle accelerator, like the ones at Cern, with the reactor core.

That may sound bizarre upon first reading, but there's good science here. [ . . . ]

[Oscar]

Edwards: Thinking About Thorium (September 16 2012)

Thinking About Thorium

by Gordon Edwards, CCNR, September 16 2012

http://ccnr.org/think_about_thorium.pdf

On CBC's "Quirks and Quarks" radio program aired on Saturday, September 15, 2012, there was an enthusiastic endorsement of "thorium reactors" as a nearly miraculous form of nuclear energy that will avoid all of the problems now associated with uranium-based nuclear power. I have been asked by several people to give my own personal opinion of this prospect, and accordingly have written the following:

Background:

When nuclear power was first presented to a credulous public, fully conditioned to respect science and admire scientists, people were quick to believe that nuclear power was safe, clean, cheap and inexhaustible -- just because scientists said so. It was also said that "peaceful" nuclear power had nothing whatsoever to do with atomic bombs and the proliferation of nuclear weapons.

It took decades for people to realize that these are all lies.

I can't believe that people are now so eager to swallow the hype about thorium with all its over-the-top claims of being safe, clean, cheap, inexhaustible, unrelated to nuclear weapons, and even a miraculous way of solving the nuclear waste problems created by the previous generation of -- what? -- safe, clean, cheap, inexhaustible, unrelated to nuclear weapons, nuclear reactors.

As the old saying goes, "once burned, twice shy". Or more explicitly, "Fool me once, shame on you. Fool me twice, shame on me."

If thorium was such a good idea then its promoters would be more willing to tell the truth rather than to spin fairy tales about it.

Fairy Tale #1. "Thorium is a nuclear fuel."

False. Thorium is NOT a nuclear fuel. Fill the interior of ANY nuclear reactor with fuel assemblies made of thorium, and absolutely nothing will happen. Because thorium is not a "fissile" material -- it cannot sustain a nuclear chain reaction, no matter what.

The truth is that uranium-233 is a fissile material that can be used either as fuel for a nuclear reactor or as the explosive material in a nuclear weapon. (The USA exploded an atomic bomb made from uranium-233 more than half a century ago, in 1955.)

But uranium-233 does not exist in the natural world. It can only be created by bombarding thorium-232 with neutrons. When a thorium-232 atom absorbs a neutron it becomes transmuted into a uranium-233 atom.

So the bottom line is that thorium (meaning thorium-232) is not a nuclear fuel nor is it a nuclear explosive, but it can be used as a raw material to produce uranium-233 which is both a nuclear fuel and a nuclear explosive.

It seems to me that if thorium proponents want to be believed, they should explain these simple facts to people right away instead of "preying on their ignorance" by telling them untruths.

Fairy Tale #2. "The use of thorium as a "nuclear fuel" [sic] has nothing to do with nuclear weapons or nuclear explosive materials."

This is wrong in several ways.

As already mentioned, thorium has to be converted into uranium-233 before "it" can be used as a nuclear fuel -- so already we have a link with nuclear weapons. While uranium-233 does have some disadvantages as a nuclear explosive material (mainly due to the presence of gamma radiation) it also has some terrific advantages for the would-be bomb-maker.

The main advantage is that uranium-233 is 100% enriched whereas naturally-occurring uranium-235 is NEVER 100% enriched. The higher the degree of enrichment, the more powerful the nuclear explosive.

But nuclear weapons are involved at the very BEGINNING of thorium reactors, because you cannot get the thorium reactor started without mixing the thorium with some weapons-explosive material -- either plutonium or highly enriched uranium. That means that you cannot even START using thorium for energy unless you first either

(1) separate plutonium from irradiated nuclear fuel using reprocessing technology, as North Korea has done for example (and used the plutonium in nuclear weapons), or

(2) produced highly enriched uranium in a uranium enrichment facility as Iran has done, much to the consternation of the rest of the world,

Yeah! Let's hear it for "peaceful" thorium reactors!

Fairy Tale #3, 4, 5, ... Thorium reactors cannot undergo a catastrophic accident, will not produce very much nuclear waste, will reduce the "storage time" from millions of years to hundreds of years, etc, etc.

These are all profoundly misleading exaggerations. Any bomb dropped on a thorium reactor will result in a catastrophic accident.

Thorium reactors produce high-level radioactive waste just like today's reactors, and although the proportions of various radio-nuclides may be substantially different, there is NO WAY that a thorium reactor will eliminate all radioactive elements having half-lives measured in the tens of thousands of years.

Thorium is an old idea that has been promoted many times in the past. In 1977, Atomic Energy of Canada Limited urged the Canadian government to invest billions of dollars in thorium reprocessing technology of nightmarish proportions.

This is documented on the CCNR web site -- see
[ http://www.ccnr.org/AECL_plute.html ] [my account]
and [ http://www.ccnr.org/aecl_plute_seminar.html ] [industry's plan]

The moral of this story is: don't be too eager to buy a pig in a poke, especially when you have heard this kind of exuberant sales pitch before -- and you know how THAT turned out!

Best wishes for a nuclear-weapons and nuclear-energy free future.

Gordon Edwards.

P.S. Here's what I wrote on this subject a while ago....

GE

- - - - -

Thorium Reactors: Back to the Dream Factory

[/b]by Gordon Edwards, July 13, 2011

The Nuclear Dream Factory

Every time a nuclear power reactor idea doesn't work out, and ordinary people get down-hearted and even start to doubt the magnificence and benificence of nuclear energy, the nuclear proponents rush back to their well-stocked dream factory to fetch another idea -- one that is sufficiently unfamiliar and sufficiently untested that ordinary people have no idea whether it is good or bad, safe or dangerous, feasible or foolish, or whether the almost miraculous claims made about it are true or false.

Just a few years ago, nuclear proponents were pushing Generation 3 reactors -- enormous plants that would generate huge amounts of electricity, yet be cheaper and faster to build than earlier models, as well as being safer and longer-lived.

Then Areva ran into a blizzard of problems trying to build one of these behemoths in Finland -- the cost soaring by billions of dollars, the construction time extended by years, and fundamental safety-related design problems surfacing late in the game. Check and mate.

Undaunted, nuclear proponents quickly executed a 180-degree turn and are now promoting small reactors which can be mass-produced by the thousands and sprinkled on the landscape like cinnamon on toast. Pebble-bed reactors, molten-salt reactors, thorium reactors, have been paraded before the public with as many bells and whistles as the nuclear industry can muster, to distract people's gaze away from the construction fiascos, the litany of broken promises from the past, the still-unsolved problems of nuclear waste and weapons proliferation, and the horror that is Fukushima.

The following paragraphs are written to dispel some of the mystique surrounding the idea of "thorium reactors" -- a very old idea that is now being dressed up in modern clothes and made to seem like a major scientific breakthrough, which it is not.

Thorium is not a nuclear fuel

The fundamental fact about thorium is that it is NOT a nuclear fuel, because thorium is not a fissile material, meaning that it cannot sustain a nuclear fission chain reaction.

In fact the ONLY naturally occurring fissile material is uranium-235, and so -- of necessity -- that is the material that fuels all of the first-generation reactors in the entire world. Thorium cannot r eplace uranium-235 in this regard. Not at all.

Thorium is a "fertile" material

But thorium-232, which is a naturally occurring radioactive material, is about three times as abundant as uranium-238, which is also a naturally occurring radioactive material. Neither of these materials can be used directly as a nuclear fuel, because they are not "fissile" materials.

However, both uranium-238 and thorium-232 are "fertile" materials, which means that IF they are placed in the core of a nuclear reactor (one that is of necessity fuelled by a fissile material), some fraction of those fertile atoms will be transmuted into man-made fissile atoms.

Some uranium-238 atoms get transmuted into plutonium-239 atoms, and some thorium-232 atoms get transmuted into uranium-233 atoms.

Both plutonium-239 and uranium-233 are fissile materials which are not naturally-occurring. They are both usable as either fuel for nuclear
reactors or as nuclear explosive materials for bombs.

(The USA exploded an atomic bomb made from U-233 in 1955.)

Reprocessing of irradiated nuclear fuel

In general, to obtain quantities of plutonium-239 or uranium-233, it is necessary to "reprocess" the irradiated material that started out as
uranium-238 or thorium-232. This means dissolving that irradiated material in acid and then chemically separating out the fissile
plutonium-239 or uranium-233, leaving behind the liquid radioactive wastes which include fission products (broken pieces of split atoms,
including such things as iodine-131, cesium-137, strontium-90, etc.) and other radioactive waste materials called "activation products" and
"transuranic elements"

Reprocessing is the dirtiest process in the entire nuclear fuel chain, because of the gaseous radioactive releases, liquid radioactive discharges, and large quantities of highly dangerous and easily dispersible radioactive liquids. Reprocessing also poses great proliferation risks because it produces man-made fissile materials which can be incorporated into nuclear weapons of various kinds by anyone who acquires the separated fissile material.

Advanced Fuel Cycles and Breeders

" Any nuclear reactor-fuelling regime that requires reprocessing, or that uses plutonium-239 or uranium-233 as a primary reactor fuel, is called an "advanced fuel cycle". These advanced fuel cycles are intimately related with the idea of a "breeder" reactor -- one which creates as much or more fissile material as a byproduct than the amount of fissile material used to fuel the reactor.

So it is only in this context that thorium reactors make any sense at all -- like all breeder concepts, they are designed to extend the fuel supply of nuclear reactors and thus prolong the nuclear age by centuries.

The breeder concept is very attractive to those who envisage a virtually limitless future for nuclear reactors, because the naturally occurring uranium-235 supply is not going to outlast the oil supply. Without advanced fuel cycles, nuclear power is doomed to be just a "flash in the pan".

Thorium reactors are most enthusiastically promoted by those who see "plutonium breeders" as the only other realistic alternative to bring about a long-lived nuclear future. They think that thorium/uranium-233 is a better fate than uranium/plutonium-239.

They do not see a nuclear phaseout as even remotely feasible or attractive.

"Molten Salt" reactors

Molten salt reactors are not a new idea, and they do not in any way require the use of thorium -- although historically the two concepts have often been linked.

The basic idea of using molten salt instead of water (light or heavy water) as a coolant has a number of distinct advantages, chief of which is the ability to achieve much higher temperatures (650 deg. C instead of 300 deg. C) than with water cooled reactors, and at a much lower vapour pressure.

The higher temperature means greater efficiency in converting the heat into electricity, and the lower pressure means less likelihood of an over-pressure rupture of pipes, and less drastic consequences of such ruptures if and when they do occur.

Molten salt reactors were researched at Oak Ridge Tennessee throughout the 1960s, culminating in the Molten Salt Reactor Experiment (MSRE), producing 7.4 megawatts of heat but no electricity.

It was an early prototype of a thorium breeder reactor, using uranium and plutonium as fuels but not using the thorium blanket which would
have been used to "breed" uranium-233 to be recovered through reprocessing -- the ultimate intention of the design.

This Oak Ridge work culminated in the period from 1970-76 in a design for a Molten Salt Breeder Reactor (MSBR) using thorium as a "fertile
material" to breed "fissile" uranium-233, which would be extracted using a reprocessing facility.

Molten Salt Thorium reactors without reprocessing?

Although it is theoretically possible to imagine a molten-salt reactor design where the thorium-produced uranium-233 is immediately used as a reactor fuel without any actual reprocessing, such reactor designs are very inefficient in the "breeding" capacity and pose financial disincentives of a serious nature to any would-be developer. No one has actually built such a reactor or has plans to build such a reactor because it just isn't worth it compared with those designs which have a reprocessing facility.

Here's what Wikipedia says on this matter (it happens to be good info):

[ http://en.wikipedia.org/wiki/Molten_salt_reactor ]

To exploit the molten salt reactor's breeding potential to the fullest, the reactor must be co-located with a reprocessing facility. Nuclear reprocessing does not occur in the U.S. because no commercial provider is willing to undertake it. The regulatory risk and associated costs are very great because the regulatory regime has varied dramatically in different administrations.[20] UK, France, Japan, Russia and India currently operate some form of fuel reprocessing.

Some U.S. Administration departments have feared that fuel reprocessing in any form could pave the way to the plutonium economy with its associated proliferation dangers.[21]

A similar argument led to the shutdown of the Integral Fast Reactor project in 1994.[22] The proliferation risk for a thorium fuel cycle stems from the potential separation of uranium-233, which might be used in nuclear weapons, though only with considerable difficulty.

Currently the Japanese are working on a 100-200 MWe molten salt thorium breeder reactor, using technologies similar to those used at
Oak Ridge, but the Japanese project seems to lack funding.

Thorium reactors do not eliminate problems

The bottom line is this. Thorium reactors still produce high-level radioactive waste, they still pose problems and opportunities for the
proliferation of nuclear weapons, they still pose catastrophic accident scenarios as potential targets for terrorist or military attack, for example.

Proponents of thorium reactors argue that all of these risks are somewhat reduced in comparison with the conventional plutonium breeder concept. Whether this is true or not, the fundamental problems associated with nuclear power have by no means been eliminated.

Gordon Edwards, Ph.D., President,
Canadian Coalition for Nuclear Responsibility.