Nuclear Weapons and 'Generation 4' Reactors

Nuclear Weapons and 'Fourth Generation' Reactors

Jim Green

July 2009

A version of this article was published in FoE Australia's magazine Chain Reaction, August 2009.

'Integral fast reactors' and other 'fourth generation' nuclear power concepts have been gaining attention, in part because of comments by US climate scientist James Hansen. While not a card-carrying convert, Hansen argues for more research: "We need hard-headed evaluation of how to get rid of long-lived nuclear waste and minimize dangers of proliferation and nuclear accidents. Fourth generation nuclear power seems to have the potential to solve the waste problem and minimize the others."

Others are less circumspect, with one advocate of integral fast reactors promoting them as the "holy grail" in the fight against global warming. There are two main problems with these arguments. Firstly, nuclear power could at most make a modest contribution to climate change abatement, mainly because it is used almost exclusively for electricity generation which accounts for about one-quarter of global greenhouse emissions. Doubling global nuclear power output (at the expense of coal) would reduce greenhouse emissions by about 5%. Building six nuclear power reactors in Australia (at the expense of coal) would reduce Australia's emissions by just 4%.

The second major problem with the nuclear 'solution' to climate change is that all nuclear power concepts (including 'fourth generation' concepts) fail to address the single greatest problem with nuclear power − its repeatedly-demonstrated connection to the proliferation of Weapons of Mass Destruction (WMD). Not just any old WMDs but nuclear weapons − the most destructive, indiscriminate and immoral of all weapons.

Integral fast reactors

Integral fast reactors (IFRs) are reactors proposed to be fuelled with a metallic alloy of uranium and plutonium, with liquid sodium as the coolant. 'Fast' because they would use unmoderated neutrons as with other plutonium-fuelled fast neutron reactors (e.g. breeders). 'Integral' because they would operate in conjunction with on-site 'pyroprocessing' to separate plutonium and other long-lived radioisotopes and to re-irradiate (both as an additional energy source and to convert long-lived waste products into shorter-lived, less problematic wastes).

IFRs would breed their own fuel (plutonium-239) from uranium-238 contained in abundant stockpiles of depleted uranium. Thus there would be less global demand for uranium mining with its attendant problems, and less demand for uranium enrichment plants which can be used to produce low-enriched uranium for power reactors or highly enriched uranium for weapons. Drawing down depleted uranium stockpiles would be welcome because of the public health and environmental problems they pose and because one of the few alternative uses for depleted uranium − hardening munitions − is objectionable.

Pyroprocessing technology would be used − it would not separate pure plutonium suitable for direct use in nuclear weapons, but would keep the plutonium mixed with other long-lived radioisotopes such that it would be very difficult or impossible to use directly in nuclear weapons. Recycling plutonium generates energy and gets rid of the plutonium with its attendant proliferation risks. These advantages could potentially be achieved with conventional reprocessing and plutonium use in MOX (uranium/plutonium oxide) reactors or fast neutron reactors. IFR offers one further potential advantage − transmutation of long-lived waste radioisotopes to convert them into shorter-lived waste products.

In short, IFRs could produce lots of greenhouse-friendly energy and while they're at it they can 'eat' nuclear waste and convert fissile materials, which might otherwise find their way into nuclear weapons, into useful energy. Too good to be true? Sadly, yes. Nuclear engineer Dave Lochbaum from the Union of Concerned Scientists writes: "The IFR looks good on paper. So good, in fact, that we should leave it on paper. For it only gets ugly in moving from blueprint to backyard."

Complete IFR systems don't exist. Fast neutron reactors exist but experience is limited and they have had a troubled history. The pyroprocessing and waste transmutation technologies intended to operate as part of IFR systems are some distance from being mature. But even if the technologies were fully developed and successfully integrated, IFRs would still fail a crucial test − they can too easily be used to produce fissile materials for nuclear weapons.

IFRs and nuclear weapons

George Stanford, who worked on an IFR R&D program in the US, notes that proliferators "could do [with IFRs] what they could do with any other reactor − operate it on a special cycle to produce good quality weapons material."

As with conventional reactors, IFRs can be used to produce weapon grade plutonium in the fuel (using a shorter-than-usual irradiation time) or by irradiating a uranium or depleted uranium 'blanket' or targets. Conventional PUREX reprocessing can be used to separate the plutonium. Another option is to separate reactor grade plutonium from IFR fuel and to use that in weapons instead of weapon grade plutonium.

The debate isn't helped by the muddle-headed inaccuracies of some IFR advocates, including some who should know better. For example, Prof. Barry Brook from Adelaide University says: "IFRs cannot produce weapons-grade plutonium. The integral fast reactor is a systems design with a sodium-cooled reactor with metal fuels and pyroprocessing on-site. To produce weapons-grade plutonium you would have to build an IFR+HSHVHSORF (highly specialised, highly visible, heavily shielded off-site reprocessing facility). You would also need to run your IFR on a short cycle." Or to paraphrase: IFRs can't produce weapon grade plutonium, IFRs can produce weapon grade plutonium. Go figure.

Presumably Brook's point is that IFR-produced plutonium cannot be separated on-site from irradiated materials (fuel/blanket/targets); it would need to be separated from irradiated materials at a separate reprocessing plant. If so, it is a banal point which also applies to conventional reactors, and it remains the case that IFRs can certainly produce weapon grade plutonium.

Brooks' HSHVHSORFs are conventional PUREX plants − technology which is well within the reach of most or all nation states. Existing reprocessing plants would suffice for low-burn-up IFR-irradiated materials while more elaborate shielding might be required to safely process materials irradiated for a longer period. IFR advocate Tom Blees notes that: "IFRs are certainly not the panacea that removes all threat of proliferation, and extracting plutonium from it would require the same sort of techniques as extracting it from spent fuel from light water reactors."

IFR advocates propose using them to draw down global stockpiles of fissile material, whether derived from nuclear research, power or WMD programs. However, IFRs have no need for outside sources of fissile material beyond their initial fuel load. Whether they are used to irradiate outside sources of fissile material to any significant extent would depend on a confluence of commercial, political and military interests. History shows that non-proliferation objectives receive low priority. Conventional reprocessing with the use of separated plutonium as fuel (in breeders or MOX reactors) has the same potential to drawn down fissile material stockpiles, but has increased rather than decreased proliferation risks. Very little plutonium has been used as reactor fuel in breeders or MOX reactors. But the separation of plutonium from spent fuel continues and stockpiles of separated 'civil' plutonium − which can be used directly in weapons − are increasing by about five tonnes annually and amount to over 270 tonnes, enough for 27,000 nuclear weapons.

IFR advocates demonstrate little or no understanding of the realpolitik imposed by the commercial, political and military interests responsible for, amongst other things, unnecessarily creating this problem of 270+ tonnes of separated civil plutonium and failing to take the simplest steps to address the problem − namely, suspending reprocessing or reducing the rate of reprocessing such that plutonium stockpiles are drawn down rather than continually increasing.

The proposed use of IFRs to irradiate fissile materials produced elsewhere faces the familiar problem that countries with the greatest interest in WMD production will be the least likely to forfeit fissile material stockpiles and vice versa. Whatever benefits arise from the potential consumption of outside sources of fissile material must be weighed against the problem that IFRs could themselves be used to produce fissile material for weapons. WMD proliferators won't use IFRs to draw down stockpiles of their own fissile material let alone anyone else's − they are more likely to use them to produce plutonium for nuclear weapons.

Some IFR proponents propose initially deploying IFR technology in nuclear weapons states and weapons-capable states, but every other proposal for selective deployment of dual-use nuclear technology has been rejected by countries that would be excluded.


Some IFR advocates downplay the proliferation risks by arguing that fissile material is more easily produced in research reactors. But producing fissile material for weapons in IFRs would not be difficult. Extracting irradiated material from an IFR may be challenging though not from those IFRs which have been designed to produce the initial fuel load for other IFRs (and are thus designed to facilitate the insertion and extraction of uranium targets).

The main challenge would be to circumvent safeguards. Proponents of IFR acknowledge the need for a rigorous safeguards system to detect and deter the use of IFRs to produce fissile material for weapons. And they generally accept that the existing safeguards system is inadequate − so much so that the former Director General of the International Atomic Energy Agency, Dr. Mohamed El Baradei, has noted that the IAEA's basic rights of inspection are "fairly limited", that the safeguards system suffers from "vulnerabilities" and "clearly needs reinforcement", that efforts to improve the system have been "half-hearted", and that the safeguards system operates on a "shoestring budget ... comparable to that of a local police department".

Blees argues for a radically strengthened safeguards system including the establishment of an international strike force on full standby to attend promptly to any detected attempts to misuse IFRs or to divert nuclear materials. But there's no evidence of IFR advocates getting off their backsides to engage in the laborious work of trying to bring about improvements in safeguards. Evidently they do not accept the argument that proponents of dual-use technology have a responsibility to engage in that laborious work. Nor do they see strengthened safeguards as a prerequisite for the widespread deployment of IFRs. Yet, when pressed, IFR advocates point to safeguards which exist only in their imaginations: we needn't worry about IFRs and WMD proliferation, for example, because Blees' international strike force will take care of that. Such arguments are circular and disingenuous.

IFR advocates imagine that a strong commitment to nuclear non-proliferation will shape the development and deployment of IFR technology, but in practice it could easily fall prey to the interests responsible for turning attractive theories into the fiasco of ever-growing stockpiles of separated civil plutonium. Under the Bush administration, proposals for advanced, 'proliferation-resistant' reprocessing under the Global Nuclear Energy Partnership gave way to a plan to expand conventional reprocessing while working on R&D into advanced reprocessing. A similar fate could easily befall proposals to run fast neutron reactors in conjunction with 'proliferation-resistant' reprocessing.

IFR proponents want to avoid the risks associated with widespread transportation of nuclear and fissile materials by co-locating a pyroprocessing facility with every IFR reactor plant − but nuclear utilities might prefer the cost savings associated with centralised processing.

As another example of the potential for attractive theories to turn into problematic outcomes, the fissile material required for the initial IFR fuel loading would ideally come from civil and military stockpiles or from other IFRs − but that fissile material requirement could be used to justify the ongoing operation of enrichment and PUREX reprocessing plants and to justify the construction of new ones.

In his book 'Prescription for the Planet', Blees argues that: "Privatized nuclear power should be outlawed worldwide, with complete international control of not only the entire fuel cycle but also the engineering, construction, and operation of all nuclear power plants. Only in this way will safety and proliferation issues be satisfactorily dealt with. Anything short of that opens up a Pandora's box of inevitable problems." He goes further, arguing for a "nonprofit global energy consortium" to control nuclear power: "The shadowy threat of nuclear proliferation and terrorism virtually requires us to either internationalize or ban nuclear power."

But there's little or no discussion among IFR advocates about how to bring about these fundamental changes, nor any sense that proponents of IFRs and other dual-use technology ought to be part of that struggle, and these fundamental changes are not seen as a prerequisite for the deployment of IFRs.

It would be silly to oppose nuclear power reactors in a hypothetical world where rigorous safeguards ensured that they would not be used to produce fissile material for weapons, where no expense was spared to minimise the short- and long-term environmental and public health hazards, where genuinely independent regulators provided strict oversight, and where the corrupting effects of the profit motive and nationalism had been eliminated. In other words, it would be silly to oppose nuclear power if all the rational reasons for that opposition were satisfactorily addressed. But that tells us nothing about the real world.

Other 'fourth generation' reactor types

IFRs and other plutonium-based nuclear power concepts fail the WMD proliferation test, i.e. they can too easily be used to produce fissile material for nuclear weapons. Conventional reactors also fail the test because they produce plutonium and because they legitimise the operation of enrichment plants and reprocessing plants.

The use of thorium as a nuclear fuel doesn't solve the WMD proliferation problem. Irradiation of thorium (indirectly) produces uranium-233, a fissile material which can be used in nuclear weapons. The US has successfully tested weapons using uranium-233 (and France may have too). India's thorium program must have a WMD component − as evidenced by India's refusal to allow IAEA safeguards to apply to its thorium program. Thorium fuelled reactors could also be used to irradiate uranium to produce weapon grade plutonium. The possible use of highly enriched uranium (HEU) or plutonium to initiate a thorium-232/uranium-233 reaction, or proposed systems using thorium in conjunction with HEU or plutonium as fuel, present further risks of diversion of HEU or plutonium for weapons production as well as providing a rationale for the ongoing operation of dual-use enrichment and reprocessing plants.

Some proponents of nuclear fusion power falsely claim that it would pose no risk of contributing to weapons proliferation. In fact, there are several risks, the most important of which is the use of fusion reactors to irradiate uranium to produce plutonium or to irradiate thorium-232 to produce uranium-233.

Fusion power has yet to generate a single Watt of useful electricity but it has already contributed to proliferation problems. According to Khidhir Hamza, a senior nuclear scientist involved in Iraq's weapons program in the 1980s: "Iraq took full advantage of the IAEA's recommendation in the mid 1980s to start a plasma physics program for "peaceful" fusion research. We thought that buying a plasma focus device ... would provide an excellent cover for buying and learning about fast electronics technology, which could be used to trigger atomic bombs."

All existing and proposed nuclear power concepts pose WMD proliferation risks. History gives us some indication of the scale of the problem. Over 20 countries have used their 'peaceful' nuclear facilities for some level of weapons research and five countries developed nuclear weapons under cover of a civil program.

Former US Vice President Al Gore has summed up the problem of heavy reliance on nuclear power for climate change abatement: "For eight years in the White House, every weapons-proliferation problem we dealt with was connected to a civilian reactor program. And if we ever got to the point where we wanted to use nuclear reactors to back out a lot of coal ... then we'd have to put them in so many places we'd run that proliferation risk right off the reasonability scale."

Make-believe nuclear reactors

In addition to dishonest or ill-informed claims that 'fourth generation' nuclear power will satisfactorily address WMD proliferation concerns, its proponents also claim that it will be safe, cheap, simple, flexible etc.

Amory Lovins from the Rocky Mountain Institute has summarised the differences between real and make-believe nuclear reactors:

"An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose. (7) Very little development will be required. It will use off the shelf components. (8) The reactor is in the study phase. It is not being built now.

"On the other hand a practical reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.

"Every new type of reactor in history has been costlier, slower, and harder than projected. ...

"In short, the notion that different or smaller reactors plus wholly new fuel cycles (and, usually, new competitive conditions and political systems) could overcome nuclear energy's inherent problems is not just decades too late, but fundamentally a fantasy. Fantasies are all right, but people should pay for their own. Investors in and advocates of small-reactor innovations will be disappointed. But in due course, the aging advocates of the half-century-old reactor concepts that never made it to market will retire and die, their credulous young devotees will relearn painful lessons lately forgotten, and the whole nuclear business will complete its slow death of an incurable attack of market forces."

More information on IFRs is posted at

See also relevant papers posted at:

A debate on IFRs is posted at

Amory Lovins' article, 'New nuclear reactors, same old story', is posted at

More information on second, third and fourth generation reactors:

Hirsch, Helmut, Oda Becker, Mycle Schneider and Antony Froggatt, April 2005, "Nuclear Reactor Hazards: Ongoing Dangers of Operating Nuclear Technology in the 21st Century", Report prepared for Greenpeace International, <>.