Nuclear Weapons and ‘Generation 4’ Reactors


On the proliferation risks associated with thorium please use this link:

Nuclear Weapons and ‘Generation 4’ Reactors

Jim Green – Friends of the Earth Australia.

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,

James Hansen’s Generation IV nuclear fallacies and fantasies

Jim Green, Nuclear Monitor #849,

The two young co-founders of nuclear engineering start-up Transatomic Power were embarrassed earlier this year when their claims about their molten salt reactor design were debunked, forcing some major retractions.1

The claims of MIT nuclear engineering graduate students – Leslie Dewan and Mark Massie – were trumpeted in MIT’s Technology Review under the headline, ‘What if we could build a nuclear reactor that costs half as much, consumes nuclear waste, and will never melt down?’2

The Technology Review puff-piece said Dewan “introduced new materials and a new shape that allowed her to increase power output by 30 times. As a result, the reactor is now so compact that a version large enough for a power plant can be built in a factory and shipped by rail to a plant site, which is potentially cheaper than the current practice of building nuclear reactors on site. The reactor also makes more efficient use of the energy in nuclear fuel. It can consume about one ton of nuclear waste a year, leaving just four kilograms behind. Dewan’s name for the technology: the Waste-Annihilating Molten-Salt Reactor.”2

A February 2017 article in MIT’s Technology Review ‒ this one far more critical ‒ said: “Those lofty claims helped it raise millions in venture capital, secure a series of glowing media profiles (including in this publication), and draw a rock-star lineup of technical advisors.”1

MIT physics professor Kord Smith debunked a number of Transatomic’s key claims. Smith says he asked Transatomic to run a test which, he says, confirmed that “their claims were completely untrue.”1

Transatomic’s claim that the ‘Waste-Annihilating Molten-Salt Reactor’ could “generate up to 75 times more electricity per ton of mined uranium than a light-water reactor” was severely downgraded to “more than twice.”1 And the company abandoned its waste-to-fuel claims and now says that a reactor based on the current design would not use waste as fuel and thus would “not reduce existing stockpiles of spent nuclear fuel”.1

Hansen’s Generation IV propaganda

Kennedy Maize wrote about Transatomic’s troubles in Power Magazine: “[T]his was another case of technology hubris, an all-to-common malady in energy, where hyperbolic claims are frequent and technology journalists all too credulous.”3 Pro-nuclear commentator Dan Yurman said that “other start-ups with audacious claims are likely to receive similar levels of scrutiny” and that it “may have the effect of putting other nuclear energy entrepreneurs on notice that they too may get the same enhanced levels of analysis of their claims.”4

Well, yes, others making false claims about Generation IV reactor concepts might receive similar levels of scrutiny … or they might not. Arguably the greatest sin of the Transatomic founders was not that they inadvertently spread misinformation, but that they are young, and in Dewan’s case, female. Aging men seem to have a free pass to peddle as much misinformation as they like without the public shaming that the Transatomic founders have been subjected to. A case in point is climate scientist James Hansen. We’ve repeatedly drawn attention to Hansen’s nuclear misinformation in Nuclear Monitor5-9 ‒ but you’d struggle to find any critical commentary outside the environmental and anti-nuclear literature.

Hansen states that a total requirement of 115 new reactor start-ups per year to 2050 would be required to replace fossil fuel electricity generation ‒ a total of about 4,000 reactors.10 Let’s assume that Generation IV reactors do the heavy lifting, and let’s generously assume that mass production of Generation IV reactors begins in 2030. That would necessitate about 200 reactor start-ups per year from 2030 to 2050 ‒ or four every week. Good luck with that.

Moreover, the assumption that mass production of Generation IV reactors might begin in or around 2030 is unrealistic. A report by the French Institute for Radiological Protection and Nuclear Safety − a government authority under the Ministries of Defense, the Environment, Industry, Research, and Health − states: “There is still much R&D to be done to develop the Generation IV nuclear reactors, as well as for the fuel cycle and the associated waste management which depends on the system chosen.”11

Likewise, a US Government Accountability Office report on the status of small modular reactors (SMRs) and other ‘advanced’ reactor concepts in the US concluded: “Both light water SMRs and advanced reactors face additional challenges related to the time, cost, and uncertainty associated with developing, certifying or licensing, and deploying new reactor technology, with advanced reactor designs generally facing greater challenges than light water SMR designs. It is a multi-decade process, with costs up to $1 billion to $2 billion, to design and certify or license the reactor design, and there is an additional construction cost of several billion dollars more per power plant.”12

An analysis recently published in the peer-reviewed literature found that the US government has wasted billions of dollars on Generation IV R&D with little to show for it.13 Lead researcher Dr Ahmed Abdulla, from the University of California, said that “despite repeated commitments to non-light water reactors, and substantial investments … (more than $2 billion of public money), no such design is remotely ready for deployment today.”14


In a nutshell, Hansen and other propagandists claim that some Generation IV reactors are a triple threat: they can convert weapons-usable (fissile) material and long-lived nuclear waste into low-carbon electricity. Let’s take the weapons and waste issues in turn.

Hansen says Generation IV reactors can be made “more resistant to weapons proliferation than today’s reactors”15 and “modern nuclear technology can reduce proliferation risks”.16 But are new reactors being made more resistant to weapons proliferation and are they reducing proliferation risks? In a word: No. Fast neutron reactors have been used for weapons production in the past (e.g. by France17) and will likely be used for weapons production in future (e.g. by India).

India plans to produce weapons-grade plutonium in fast breeder reactors for use as driver fuel in thorium reactors.18 Compared to conventional uranium reactors, India’s plan is far worse on both proliferation and security grounds. To make matters worse, India refuses to place its fast breeder / thorium program under IAEA safeguards.19

Hansen claims that thorium-based fuel cycles are “inherently proliferation-resistant”.20 That’s garbage ‒ thorium has been used to produce fissile material (uranium-233) for nuclear weapons tests.21 Again, India’s plans provide a striking real-world refutation of Hansen’s dangerous misinformation.

Hansen states that if “designed properly”, fast neutron reactors would generate “nothing suitable for weapons”.20 What does that even mean? Are we meant to ignore actual and potential links between Generation IV nuclear technology and WMD proliferation on the grounds that the reactors weren’t built “properly”? And if we take Hansen’s statement literally, no reactors produce material suitable for weapons ‒ the fissile material must always be separated from irradiated materials ‒ in which case all reactors can be said to be “designed properly”. Hooray.

Hansen claims that integral fast reactors (IFR) ‒ a non-existent variant of fast neutron reactors ‒ “could be inherently free from the risk of proliferation”.22 That’s another dangerous falsehood.23 Dr 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.”24

Hansen acknowledges that “nuclear does pose unique safety and proliferation concerns that must be addressed with strong and binding international standards and safeguards.”10 There’s no doubting that the safeguards systems needs strengthening.25 In articles and speeches during his tenure as the Director General of the IAEA from 1997‒2009, Dr Mohamed ElBaradei said that the Agency’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 were “half-hearted”, and that the safeguards system operated on a “shoestring budget … comparable to that of a local police department”.

Hansen says he was converted to the cause of Generation IV nuclear technology by Tom Blees, whose 2008 book ‘Prescription for the Planet’ argues the case for IFRs.26 But Hansen evidently missed those sections of the book where Blees argues for radically strengthened safeguards including the creation of an international strike-force on full standby to attend promptly to any detected attempts to misuse or to divert nuclear materials. Blees also argues that “privatized nuclear power should be outlawed worldwide” and that nuclear power must either be internationalized or banned to deal with the “shadowy threat of nuclear proliferation”.26

So what is James Hansen doing about the WMD proliferation problem and the demonstrably inadequate nuclear safeguards system? This is one of the great ironies of Hansen’s nuclear advocacy ‒ he does absolutely nothing other than making demonstrably false claims about the potential of Generation IV concepts to solve the problems, and repeatedly slagging off at organizations with a strong track record of campaigning for improvements to the safeguards system.27


Hansen claims that “modern nuclear technology can … solve the waste disposal problem by burning current waste and using fuel more efficiently.”16 He elaborates: “Nuclear “waste”: it is not waste, it is fuel for 4th generation reactors! Current (‘slow’) nuclear reactors are lightwater reactors that ‘burn’ less than 1% of the energy in the original uranium ore, leaving a waste pile that is radioactive for more than 10,000 years. The 4th generation reactors can ‘burn’ this waste, as well as excess nuclear weapons material, leaving a much smaller waste pile with radioactive half-life measured in decades rather than millennia, thus minimizing the nuclear waste problem. The economic value of current nuclear waste, if used as a fuel for 4th generation reactors, is trillions of dollars.”28

But even if IFRs ‒ Hansen’s favored Generation IV concept ‒ worked as hoped, they would still leave residual actinides, and long-lived fission products, and long-lived intermediate-level waste in the form of reactor and reprocessing components … all of it requiring deep geological disposal. UC Berkeley nuclear engineer Prof. Per Peterson notes in an article published by the pro-nuclear Breakthrough Institute: “Even integral fast reactors (IFRs), which recycle most of their waste, leave behind materials that have been contaminated by transuranic elements and so cannot avoid the need to develop deep geologic disposal.”29

So if IFRs don’t obviate the need for deep geological repositories, what problem do they solve? They don’t solve the WMD proliferation problem associated with nuclear power. They would make more efficient use of finite uranium … but uranium is plentiful.

In theory, IFRs would gobble up nuclear waste and convert it into low-carbon electricity. In practice, the IFR R&D program in Idaho has left a legacy of troublesome waste. This saga is detailed in a recent article31 and a longer report32 by the Union of Concerned Scientists’ senior scientist Ed Lyman (see the following article in this issue of Nuclear Monitor). Lyman states that attempts to treat IFR spent fuel with pyroprocessing have not made management and disposal of the spent fuel simpler and safer, they have “created an even bigger mess”.31

Japan is about to get first-hand experience of the waste legacy associated with Generation IV reactors in light of the decision to decommission the Monju fast spectrum reactor. Decommissioning Monju has a hefty price-tag ‒ far more than for conventional light-water reactors. According to a 2012 estimate by the Japan Atomic Energy Agency, decommissioning Monju will cost an estimated ¥300 billion (US$2.74bn; €2.33bn).30 That estimate includes ¥20 billion to remove spent fuel from the reactor ‒ but no allowance is made for the cost of disposing of the spent fuel, and in any case Japan has no deep geological repository to dispose of the waste.

Generation IV economics

Hansen claimed in 2012 that IFRs could generate electricity “at a cost per kW less than coal.”33,34 He was closer to the mark in 2008 when he said of IFRs: “I do not have the expertise or insight to evaluate the cost and technology readiness estimates” of IFR advocate Tom Blees and the “overwhelming impression that I get … is that Blees is a great optimist.”35

The US Government Accountability Office’s 2015 report noted that technical challenges facing SMRs and advanced reactors may result in higher-cost reactors than anticipated, making them less competitive with large light-water reactors or power plants using other fuels.36

A 2015 pro-nuclear puff-piece by the International Energy Agency (IEA) and the OECD’s Nuclear Energy Agency (NEA) arrived at the disingenuous conclusion that nuclear power is “an attractive low-carbon technology in the absence of cost overruns and with low financing costs”.37 But the IEA/NEA report made no effort to spin the economics of Generation IV nuclear concepts, stating that “generation IV technologies aim to be at least as competitive as generation III technologies … though the additional complexity of these designs, the need to develop a specific supply chain for these reactors and the development of the associated fuel cycles will make this a challenging task.”37

The late Michael Mariotte commented on the IEA/NEA report: “So, at best the Generation IV reactors are aiming to be as competitive as the current − and economically failing − Generation III reactors. And even realizing that inadequate goal will be “challenging.” The report might as well have recommended to Generation IV developers not to bother.”38

Of course, Hansen isn’t the only person peddling misinformation about Generation IV economics. A recent report states that the “cost estimates from some advanced reactor companies ‒ if accurate ‒ suggest that these technologies could revolutionize the way we think about the cost, availability, and environmental consequences of energy generation.”39 To estimate the costs of Generation IV nuclear concepts, the researchers simply asked companies involved in R&D projects to supply the information!

The researchers did at least have the decency to qualify their findings: “There is inherent and significant uncertainty in projecting NOAK [nth-of-a-kind] costs from a group of companies that have not yet built a single commercial-scale demonstration reactor, let alone a first commercial plant. Without a commercial-scale plant as a reference, it is difficult to reliably estimate the costs of building out the manufacturing capacity needed to achieve the NOAK costs being reported; many questions still remain unanswered ‒ what scale of investments will be needed to launch the supply chain; what type of capacity building will be needed for the supply chain, and so forth.”39

Hansen has doubled down on his nuclear advocacy, undeterred by the Fukushima disaster; undeterred by the economic disasters of nuclear power in the US, the UK, France, Finland and elsewhere; and undeterred by the spectacular growth of renewables and the spectacular cost reductions. He needs to take his own advice. Peter Bradford, adjunct professor at Vermont Law School and a former US Nuclear Regulatory Commission member, said in response to a 2015 letter10 co-authored by Hansen:40

“The Hansen letter contains these remarkably unself-aware sentences:

‘To solve the climate problem, policy must be based on facts and not on prejudice.’

‘The climate issue is too important for us to delude ourselves with wishful thinking.’

‘The future of our planet and our descendants depends on basing decisions on facts, and letting go of long held biases when it comes to nuclear power.’

Amen, brother.”


    1. James Temple, 24 Feb 2017, ‘Nuclear Energy Startup Transatomic Backtracks on Key Promises’,
    2. Kevin Bullis, 2013, ‘What if we could build a nuclear reactor that costs half as much, consumes nuclear waste, and will never melt down?’,
    3. Kennedy Maize, 8 March 2017, ‘Molten Salt Reactor Claims Melt Down Under Scrutiny’,
    4. Dan Yurman, 26 Feb 2017, ‘An Up & Down Week for Developers of Advanced Reactors’,
    5. Nuclear Monitor #814, 18 Nov 2015, ‘James Hansen’s nuclear fantasies’,
    6. Nuclear Monitor #776, 24 Jan 2014, ‘Environmentalists urge Hansen to rethink nuclear’,
    7. Michael Mariotte, 21 April 2016, ‘How low can they go? Hansen, Shellenberger shilling for Exelon’, Nuclear Monitor #822,
    8. M.V. Ramana, 3 Dec 2015, ‘Betting on the wrong horse: Fast reactors and climate change’, Nuclear Monitor #815,
    9. Michael Mariotte, 9 Jan 2014, ‘The grassroots response to Dr. James Hansen’s call for more nukes’,
    10. James Hansen, Kerry Emanuel, Ken Caldeira and Tom Wigley, 4 Dec 2015, ‘Nuclear power paves the only viable path forward on climate change’,
    11. IRSN, 2015, ‘Review of Generation IV Nuclear Energy Systems’, Direct download:
    12. U.S. Government Accountability Office, July 2015, ‘Nuclear Reactors: Status and challenges in development and deployment of new commercial concepts’, GAO-15-652,
    13. A. Abdulla et al., 10 Aug 2017, ‘A retrospective analysis of funding and focus in US advanced fission innovation’,;
    14. 9 Aug 2017, ‘Analysis highlights failings in US’s advanced nuclear program’,
    15. James Hansen, 7 June 2014, ‘Scientists can help in planet’s carbon cut’,
    16. K. Caldeira, K. Emanuel, J. Hansen, and T. Wigley, 3 Nov 2013, ‘Top climate change scientists’ letter to policy influencers’,
    17. See pp.44-45 in Mycle Schneider, 2009, ‘Fast Breeder Reactors in France’, Science and Global Security, 17:36–53,
    18. John Carlson, 2014, submission to Joint Standing Committee on Treaties, Parliament of Australia,
    19. John Carlson, 2015, first supplementary submission to Joint Standing Committee on Treaties, Parliament of Australia,
    20. P. Kharecha et al., 2010, ‘Options for near-term phaseout of CO2 emissions from coal use in the United States’, Environmental Science & Technology, 44, 4050-4062,
    21. Nuclear Monitor #801, 9 April 2015, ‘Thor-bores and uro-sceptics: thorium’s friendly fire’,
    22. Pushker Kharecha and James Hansen, March 2013, ‘Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power’, Environment, Science and Technology,
    24. George Stanford, 18 Sept 2010, ‘IFR FaD 7 – Q&A on Integral Fast Reactors’,
    25. See section 2.12, pp.100ff, in Friends of the Earth et al., 2015, ‘Submission to the SA Nuclear Fuel Cycle Royal Commission’,
    26. Tom Blees, 2008, ‘Prescription for the Planet’,
    28. James Hansen, 2011, ‘Baby Lauren and the Kool-Aid’,
    29. Breakthrough Institute, 5 May 2014, ‘Cheap Nuclear’,
    30. Reiji Yoshida, 21 Sept 2016, ‘Japan to scrap troubled ¥1 trillion Monju fast-breeder reactor’,
    31. Ed Lyman / Union of Concerned Scientists, 12 Aug 2017, ‘The Pyroprocessing Files’,
    32. Edwin Lyman, 2017, ‘External Assessment of the U.S. Sodium-Bonded Spent Fuel Treatment Program’,
    33. Mark Halper, 20 July 2012, ‘Richard Branson urges Obama to back next-generation nuclear technology’,
    34. 27 Dec 2012, ‘Have you heard the one about the Entrepreneur, the Climate Scientist and the Nuclear Engineer?’,
    35. James Hansen, 2008, ‘Trip Report – Nuclear Power’,
    36. U.S. Government Accountability Office, July 2015, ‘Nuclear Reactors: Status and challenges in development and deployment of new commercial concepts’, GAO-15-652,
    37. International Energy Agency (IEA) and OECD Nuclear Energy Agency (NEA), 2015, ‘Projected Costs of Generating Electricity’,
    38. Michael Mariotte, ‘Nuclear advocates fight back with wishful thinking’, Nuclear Monitor #810, 9 Sept 2015,
    39. Energy Innovation Reform Project Report Prepared by the Energy Options Network, 2017, ‘What Will Advanced Nuclear Power Plants Cost? A Standardized Cost Analysis of Advanced Nuclear Technologies in Commercial Development’,
    40. Peter A. Bradford, 17 Dec 2015, ‘The experts on nuclear power and climate change’,

Fusion scientist debunks fusion power

26 April 2017, Nuclear Monitor #842, 26/04/2017,

The Bulletin of the Atomic Scientists has published a detailed critique of fusion power written by Dr Daniel Jassby, a former principal research physicist at the Princeton Plasma Physics Lab with 25 years experience working in areas of plasma physics and neutron production related to fusion energy.1

Here is a summary of his main arguments.

Jassby writes:

“[U]nlike what happens in solar fusion ‒ which uses ordinary hydrogen ‒ Earth-bound fusion reactors that burn neutron-rich isotopes have byproducts that are anything but harmless: Energetic neutron streams comprise 80 percent of the fusion energy output of deuterium-tritium reactions and 35 percent of deuterium-deuterium reactions.

“Now, an energy source consisting of 80 percent energetic neutron streams may be the perfect neutron source, but it’s truly bizarre that it would ever be hailed as the ideal electrical energy source. In fact, these neutron streams lead directly to four regrettable problems with nuclear energy: radiation damage to structures; radioactive waste; the need for biological shielding; and the potential for the production of weapons-grade plutonium 239 ‒ thus adding to the threat of nuclear weapons proliferation, not lessening it, as fusion proponents would have it.

“In addition, if fusion reactors are indeed feasible ‒ as assumed here ‒ they would share some of the other serious problems that plague fission reactors, including tritium release, daunting coolant demands, and high operating costs. There will also be additional drawbacks that are unique to fusion devices: the use of fuel (tritium) that is not found in nature and must be replenished by the reactor itself; and unavoidable on-site power drains that drastically reduce the electric power available for sale.”

All of these problems are endemic to any type of magnetic confinement fusion or inertial confinement fusion reactor that is fueled with deuterium-tritium or deuterium alone. The deuterium-tritium reaction is favored by fusion developers. Jassby notes that tritium consumed in fusion can theoretically be fully regenerated in order to sustain the nuclear reactions, by using a lithium blanket, but full regeneration is not possible in practice for reasons explained in his article.

Jassby writes: “To make up for the inevitable shortfalls in recovering unburned tritium for use as fuel in a fusion reactor, fission reactors must continue to be used to produce sufficient supplies of tritium ‒ a situation which implies a perpetual dependence on fission reactors, with all their safety and nuclear proliferation problems. Because external tritium production is enormously expensive, it is likely instead that only fusion reactors fueled solely with deuterium can ever be practical from the viewpoint of fuel supply. This circumstance aggravates the problem of nuclear proliferation …”

Weapons proliferation

Fusion reactors could be used to produce plutonium-239 for weapons “simply by placing natural or depleted uranium oxide at any location where neutrons of any energy are flying about” in the reactor interior or appendages to the reaction vessel.

Tritium breeding is not required in systems based on deuterium-deuterium reactions, so all the fusion neutrons are available for any use including the production of plutonium-239 for weapons ‒ hence Jassby’s comment about deuterium-deuterium systems posing greater proliferation risks than deuterium-tritium systems. He writes: “In effect, the reactor transforms electrical input power into “free-agent” neutrons and tritium, so that a fusion reactor fueled with deuterium-only can be a singularly dangerous tool for nuclear proliferation.”

Further, tritium itself is a proliferation risk ‒ it is used to enhance the efficiency and yield of fission bombs and the fission stages of hydrogen bombs in a process known as “boosting”, and tritium is also used in the external neutron initiators for such weapons. “A reactor fueled with deuterium-tritium or deuterium-only will have an inventory of many kilograms of tritium, providing opportunities for diversion for use in nuclear weapons,” Jassby writes.

It isn’t mentioned in Jassby’s article, but fusion has already contributed to proliferation problems even though it has yet to generate a single Watt of useful electricity. 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.”2

Other problems

Another problem is the “huge” parasitic power consumption of fusion systems ‒ “they consume a good chunk of the very power that they produce … on a scale unknown to any other source of electrical power.” There are two classes of parasitic power drain ‒ a host of essential auxiliary systems that must be maintained continuously even when the fusion plasma is dormant (of the order of 75‒100 MW), and power needed to control the fusion plasma in magnetic confinement fusion systems or to ignite fuel capsules in pulsed inertial confinement fusion systems (at least 6% of the fusion power generated). Thus a 300 MWt / 120 MWe system barely supplies on-site needs and thus fusion reactors would need to be much larger to overcome this problem of parasitic power consumption.

The neutron radiation damage in the solid vessel wall of a fusion reactor is expected to be worse than in fission reactors because of the higher neutron energies, potentially putting the integrity of the reaction vessel in peril.

Fusion fuel assemblies will be transformed into tons of radioactive waste to be removed annually from each reactor. Structural components would need to be replaced periodically thus generating “huge masses of highly radioactive material that must eventually be transported offsite for burial”, and non-structural components inside the reaction vessel and in the blanket will also become highly radioactive by neutron activation.

Molten lithium presents a fire and explosion hazard, introducing a drawback common to liquid-metal cooled fission reactors.

Tritium leakage is another problem. Jassby writes: “Corrosion in the heat exchange system, or a breach in the reactor vacuum ducts could result in the release of radioactive tritium into the atmosphere or local water resources. Tritium exchanges with hydrogen to produce tritiated water, which is biologically hazardous. Most fission reactors contain trivial amounts of tritium (less than 1 gram) compared with the kilograms in putative fusion reactors. But the release of even tiny amounts of radioactive tritium from fission reactors into groundwater causes public consternation. Thwarting tritium permeation through certain classes of solids remains an unsolved problem.”

Water consumption is another problem. Jassby writes: “In addition, there are the problems of coolant demands and poor water efficiency. A fusion reactor is a thermal power plant that would place immense demands on water resources for the secondary cooling loop that generates steam as well as for removing heat from other reactor subsystems such as cryogenic refrigerators and pumps. … In fact, a fusion reactor would have the lowest water efficiency of any type of thermal power plant, whether fossil or nuclear. With drought conditions intensifying in sundry regions of the world, many countries could not physically sustain large fusion reactors.”

Due to all of the aforementioned problems, and others, “any fusion reactor will face outsized operating costs.” Whereas fission reactors typically require around 500 employees, fusion reactors would require closer to 1,000 employees. Jassby states that it “is inconceivable that the total operating costs of a fusion reactor will be less than that of a fission reactor”.

Jassby concludes:

“To sum up, fusion reactors face some unique problems: a lack of natural fuel supply (tritium), and large and irreducible electrical energy drains to offset. Because 80 percent of the energy in any reactor fueled by deuterium and tritium appears in the form of neutron streams, it is inescapable that such reactors share many of the drawbacks of fission reactors ‒ including the production of large masses of radioactive waste and serious radiation damage to reactor components. …

“If reactors can be made to operate using only deuterium fuel, then the tritium replenishment issue vanishes and neutron radiation damage is alleviated. But the other drawbacks remain—and reactors requiring only deuterium fueling will have greatly enhanced nuclear weapons proliferation potential.”

“These impediments ‒ together with colossal capital outlay and several additional disadvantages shared with fission reactors ‒ will make fusion reactors more demanding to construct and operate, or reach economic practicality, than any other type of electrical energy generator.

“The harsh realities of fusion belie the claims of its proponents of “unlimited, clean, safe and cheap energy.” Terrestrial fusion energy is not the ideal energy source extolled by its boosters, but to the contrary: It’s something to be shunned.”

1. Daniel Jassby, 19 April 2017, ‘Fusion reactors: Not what they’re cracked up to be’, Bulletin of the Atomic Scientists,
2. Khidhir Hamza, Sep/Oct 1998, ‘Inside Saddam’s Secret Nuclear Program’, Bulletin of the Atomic Scientists, Vol. 54, No. 5,