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James Hansen's nuclear fantasies

Nuclear Monitor Issue: 
Jim Green

Climate scientist James Hansen will be promoting nuclear power − and attacking environmental and anti-nuclear groups − in the lead-up to the U.N. COP21 climate conference in Paris in December.1 The press release announcing Hansen's visit to Paris berates environmentalists for failing to support "safe and environmentally-friendly nuclear power". The press release notes that the Climate Action Network, representing all the major environmental groups, opposes nuclear power − in other words, efforts by nuclear lobbyists to split the environment movement have failed.

Hansen won't be participating in any debates against nuclear critics. His reluctance to debate may stem from his participation in a 2010 debate in Melbourne, Australia.2 The audience of 1200 people were polled before and after the debate. The pre-debate poll found an 8% margin in favour of nuclear power; the post-debate poll found a margin of 24% against nuclear power. The turn-around was so striking that Hansen's friend and colleague Barry Brook falsely claimed the vote must have been rigged by anti-nuclear and climate action groups. "I can think of no other logical explanation – statistically, such a result would be nigh impossible," Brook claimed.3

Nuclear safety

An article co-authored by Hansen and Pushker Kharecha, published in the Environment, Science and Technology journal, claims that between 1971 and 2009, "global nuclear power has prevented an average of 1.84 million air pollution-related deaths and 64 gigatonnes of CO2-equivalent greenhouse gas emissions that would have resulted from fossil fuel burning".4 They also calculate that "nuclear power could additionally prevent an average of 420 000–7.04 million deaths and 80–240 GtCO2-eq [equivalent gigatons of carbon dioxide] emissions due to fossil fuels by midcentury, depending on which fuel it replaces [gas or coal]".

Kharecha and Hansen ignore the potential of renewables and energy efficiency and conservation. Instead they set up a false choice between fossil fuels and nuclear. Even as an assessment of the relative risks of nuclear and fossil fuels, the article doesn't stack up.

Kharecha and Hansen claim that 4,900 deaths have resulted from nuclear power between 1971 and 2009. They continue: "[E]mpirical evidence indicates that the April 1986 Chernobyl accident was the world's only source of fatalities from nuclear power plant radiation fallout." Why narrow the focus from the full energy cycle to power plants? Why limit consideration of fatalities to radiation fallout alone? There have been countless fatal accidents at nuclear fuel cycle facilities.5

Kharecha and Hansen cite the UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) to justify their figure of 43 deaths from the Chernobyl disaster.6 But the UNSCEAR report did not attempt to calculate long-term deaths from radiation exposure from Chernobyl, citing "unacceptable uncertainties in the predictions". The credible estimates of the long-term cancer death toll from Chernobyl range from 9,000 (in Eastern Europe) to 93,000 (across Eastern and Western Europe).7

Hansen states: "No people died at Fukushima because of the nuclear technology." The real impacts of the disaster are summarised by radiation biologist Dr Ian Fairlie:8

"In sum, the health toll from the Fukushima nuclear disaster is horrendous. At the minimum:

  • Over 160,000 people were evacuated, most of them permanently.
  • Many cases of post-trauma stress disorder (PTSD), depression, and anxiety disorders arising from the evacuations.
  • About 12,000 workers exposed to high levels of radiation, some up to 250 mSv
  • An estimated 5,000 fatal cancers from radiation exposures in future.9
  • Plus similar (unquantified) numbers of radiogenic strokes, CVS diseases and hereditary diseases.
  • Between 2011 and 2015, about 2,000 deaths from radiation-related evacuations due to ill-health and suicides.
  • An, as yet, unquantified number of thyroid cancers.
  • An increased infant mortality rate in 2012 and a decreased number of live births in December 2011."

Regarding Fukushima, Kharecha and Hansen state that "one early analysis indicates that annual radiation doses in nearby areas were much lower than the generally accepted 100 millisievert threshold for fatal disease development." In defence of the claim regarding a 100 mSv threshold, they cite (and misrepresent) an UNSCEAR report. The UNSCEAR report10 claims that no studies provide conclusive evidence of carcinogenic effects of radiation at levels below 100 mSv − a claim that is strongly contested.11

In any case, UNSCEAR is not claiming that radiation doses below 100 mSv do not cause cancer, but rather that evidence is lacking for such effects. Indeed UNSCEAR's view is that "the current balance of available evidence tends to favour a non-threshold response for the mutational component of radiation-associated cancer induction at low doses and low dose rates."12 Kharecha and Hansen's assertion regarding a 100 mSv threshold isn't even UNSCEAR's position let alone a "generally accepted" position.

The linear no-threshold (LNT) model of radiation risk "might not be valid for the relatively low radiation doses that the public was exposed to from nuclear power plant accidents," Kharecha and Hansen state. But LNT enjoys some heavy-hitting scientific support. For example the Committee on the Biological Effects of Ionising Radiation (BEIR) of the U.S. National Academy of Sciences states that "the risk of cancer proceeds in a linear fashion at lower doses without a threshold and ... the smallest dose has the potential to cause a small increase in risk to humans."13

There is − and will always be − uncertainty regarding LNT. But the uncertainty cuts in both directions: LNT may overestimate or underestimate risks. The BEIR report13 states that "combined analyses are compatible with a range of possibilities, from a reduction of risk at low doses to risks twice those upon which current radiation protection recommendations are based", and it further states: "Departures from a linear model at low doses, however, could either increase or decrease the risk per unit dose."

Hansen misrepresents relevant scientific institutions (UNSCEAR on the 100 mSv threshold), ignores whatever doesn't suit his pro-nuclear agenda (LNT may overestimate or underestimate risks), and he even gives credence to the discredited view that low-level radiation exposure may be beneficial to human health.14

There are many reasons to conclude that Kharecha and Hansen's figure of 4,900 deaths from nuclear power from 1971 to 2009 is a gross underestimate, yet they claim that the figure "could be a major overestimate relative to the empirical value (by two orders of magnitude)".

A realistic assessment of nuclear power fatalities would include:

  • Routine emissions: UNSCEAR's estimated collective effective dose to the world population over a 50-year period of operation of nuclear power reactors and associated nuclear fuel cycle facilities is two million person-Sieverts.15 Applying LNT gives a total of 200,000 fatal cancers.
  • Radiation exposure from accidents, including Chernobyl (estimated 9,000 to 93,000 cancer fatalities) and Fukushima (estimated 5,000 long-term cancer fatalities).
  • Indirect deaths: In relation to Fukushima, Japanese academics state: "[F]or the Fukushima coastal region, no-one, not even Self-Defense Forces, could enter the area for fear of exposure to radioactive materials, and the victims were left in the area for a long period of time. This resulted in so-called indirect fatalities, people who died due to difficult and long-term evacuation, or those who committed suicide, lamenting the radioactive pollution of their farm lands and farm animals and who had lost hope to ever rebuild their lives. These are considered as fatalities related to the nuclear accident, and their numbers have risen to 1459 as of September 2013, according to the Fukushima Prefectural Office. Though they are considered indirect deaths, they would have not died if there had been no nuclear accident."16

Kharecha and Hansen ignore non-fatal impacts. For example, the permanent relocation of 350,000 people in the aftermath of the Chernobyl disaster was associated with a great deal of trauma.17 Four and a half years after the Fukushima disaster, over 110,000 of the original 160,000 evacuees remain displaced according to the Japanese government.18 Using those figures (350,000 + 110,000), and the global experience of around 16,000 reactor-years of power reactor operations19, gives a figure of 29 'nuclear refugees' per reactor-year.

When accidents and routine emissions across the energy chain are considered, renewable energy sources are clearly safer than nuclear power and fossil fuels. Yet Hansen falsely claims that "nuclear power has the best safety record of any energy technology".14

Nuclear power is safer than fossil fuels when considering accidents and routine emissions (by a wide margin, though not as wide as Kharecha and Hansen would have you believe) − but then we need to consider the unique WMD proliferation risks associated with the nuclear industry20 as well as related security issues such as attacks on nuclear facilities.21

WMD proliferation

Kharecha and Hansen acknowledge in passing the "potential mortality from proliferation of weapons-grade material", but wave it away on the grounds that it "cannot meaningfully be quantified".

Kharecha and Hansen state: "Serious questions remain about [nuclear] safety, proliferation, and disposal of radioactive waste, which we have discussed in some detail elsewhere." But the paper they cite22 barely touches upon the proliferation problem and what little it does say is mostly rubbish:

  • It falsely claims that thorium-based fuel cycles are "inherently proliferation-resistant".23
  • It falsely claims that integral fast reactors (IFRs) "could be inherently free from the risk of proliferation".24 At best, IFRs could reduce proliferation risks; they could never be "inherently free" from proliferation risks. (Moreover IFR advocates are often disingenuous in their comparisons, for example comparing IFR pyroprocessing favourably against conventional reprocessing (because pyroprocessing does not involve plutonium separation) without considering the once-through no-reprocessing option which compares favourably against both conventional reprocessing and pyroprocessing.)
  • And Kharecha and Hansen state that if "designed properly", breeder reactors would generate "nothing suitable for weapons". India's Prototype Fast Breeder Reactor will be the next fast reactor to begin operation. It will be ideal for producing weapon grade plutonium for India's weapons program, and it may well be used for that purpose since India is refusing to place it under IAEA safeguards.

Hansen and his colleagues argue that "modern nuclear technology can reduce proliferation risks".25 But are new reactors being made more resistant to weapons proliferation? In a word: No. Fast reactors have been used for weapons production in the past (e.g. by France26) and will likely be used for weapons production in future (e.g. by India). Thorium − another 'modern' nuclear technology − has also been used to produce (uranium-233) weapons (e.g. U.S.) and will likely be used for weapons production in future (e.g. India's breeder/thorium program). It is disingenuous − and dangerous − for Hansen to be waving away those realities with claims that "modern nuclear technology can reduce proliferation risks".

Generation IV nuclear technology

Here's Hansen drinking the Kool Aid:14

"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."

Hansen's views take little or no account of the real-world experience with fast neutron reactors (and Generation IV technology more generally). That real-world experience is littered with accident-prone, obscenely expensive reactors (and R&D programs).27 Most countries that have invested in fast reactor R&D programs have decided not to throw good money after bad and have abandoned those programs.

Hansen's views are also at odds with reports published this year by the French and U.S. governments. The report by the French Institute for Radiological Protection and Nuclear Safety (IRSN) − 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."28

IRSN is also sceptical about safety claims: "At the present stage of development, IRSN does not notice evidence that leads to conclude that the systems under review are likely to offer a significantly improved level of safety compared with Generation III reactors, except perhaps for the VHTR [Very High Temperature Reactors] ..." Moreover the VHTR system could bring about significant safety improvements "but only by significantly limiting unit power".

The U.S. Government Accountability Office released a report in July on the status of small modular reactors (SMRs) and other 'advanced' reactor concepts in the U.S.29 The report concluded:

"While light water SMRs and advanced reactors may provide some benefits, their development and deployment face a number of challenges. Both SMRs and advanced reactors require additional technical and engineering work to demonstrate reactor safety and economics .... Depending on how they are resolved, these technical challenges may result in higher-cost reactors than anticipated, making them less competitive with large LWRs [light water reactors] or power plants using other fuels. ... 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 ..."

The glum assessments of the U.S. and French governments are based on real-world experience. But Hansen prefers conspiracy theories to real-world experience, claiming that an IFR R&D program in the U.S. was terminated due to pressure from environmentalists with devious motives: "I think it was because of the influence of the anti-nuclear people who realised that if this newer technology were developed it would mean that we would have an energy source that is practically inexhaustible − it could last for billions of years − and they succeeded in getting the Clinton administration to terminate the R&D for the fourth generation nuclear power plants."

So Hansen lines up with far-right nuts who claim that environmentalists want everyone living in caves. Wrong, stupid, and offensive.30 No wonder he is having so little success winning over environmentalists.

WMD proliferation was one of the concerns that led to the closure of the IFR R&D program. IFR lobbyists would have you believe that IFRs pose no proliferation risk and that they could help solve proliferation problems by using weapons material (especially plutonium) as reactor fuel. But to quote from an Argonne National Laboratory report (emphasis added): "The reactor ... could be used for excess plutonium consumption or as a breeder if needed ..."31 And Dr George Stanford, who worked on an IFR R&D program in the U.S., 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."32

Renewables and energy efficiency

Hansen states: "Can renewable energies provide all of society's energy needs in the foreseeable future? It is conceivable in a few places, such as New Zealand and Norway. But suggesting that renewables will let us phase rapidly off fossil fuels in the United States, China, India, or the world as a whole is almost the equivalent of believing in the Easter Bunny and Tooth Fairy."14

But there are credible studies for the countries that Hansen mentions:

  • U.S.A.: The Nuclear Information & Resource Service maintains a list of reports demonstrating the potential for the U.S. (and Europe) to produce all electricity from renewables.33
  • China: A 2015 report by the China National Renewable Energy Centre finds that China could generate 85% of its electricity and 60% of total energy from renewables by 2050.34
  • India: A detailed 2013 report by WWF-India and The Energy and Resources Institute maps out how India could generate as much as 90% of total primary energy from renewables by 2050.35

There is a growing body of research on the potential for renewables to largely or completely supplant fossil fuels for power supply globally.36

The doubling of global renewable energy capacity over the past decade has been spectacular37 with 783 GW of new renewable power generation capacity installed from 2005 to 2014.38 As of the end of 2014, renewables (including hydro) supplied an estimated 22.8% of global electricity (hydro 16.6% and other renewables 6.2%).37 Nuclear power's share of 10.8%39 is less than half of the electricity generation from renewables − and the gap is widening.

The International Energy Agency (IEA) anticipates another 700 GW of new renewable power capacity from 2015−2020.40 And the IEA report outlines the spectacular cost reductions: the global average costs for onshore wind generation fell by 30% from 2010−2015, and are expected to decline a further 10% by 2020; while utility-scale solar PV fell two-thirds in cost and is expected to decline another 25% by 2020.

There's also the spectacular potential of energy efficiency that Hansen sometimes ignores and sometimes pays lip-service to. A 2011 study by University of Cambridge academics concluded that a whopping 73% of global energy use could be saved by practically achievable energy efficiency and conservation measures.41 Julian Allwood, one of the authors of the study, said: "We think it's pretty unlikely that we'll find a good response to the threat of global warming on the supply side alone. But if we can make a serious reduction in our demand for energy, then all the options look more realistic."42

But let's go with Hansen's argument that renewables and energy efficiency aren't up to the job of completely supplanting fossil fuels. It's not an unreasonable place to go, given that the task is Herculean. What would make nuclear power more palatable? Super-safe, proliferation-resistant Generation IV reactor technology? Not likely.

Improved safety standards and stricter regulation could reduce the risk of catastrophic accidents. A strengthened − and properly funded − safeguards system could reduce the risks of WMD proliferation. And therein lies the greatest irony of Hansen's nuclear advocacy. Many of the environmental and anti-nuclear organisations that he attacks have a long, strong track record of campaigning for improved safety and regulatory standards and for improvements to the safeguards system. Hansen has said little and done less about those issues.

Michael Mariotte from the Nuclear Information & Resource Service neatly sums up the situation: "Dr. Hansen has done the entire world an incredible service with his focus and expertise on climate and his unrelenting warnings that the global community must act to prevent a climate catastrophe. We agree completely. But Dr. Hansen's expertise is climate, not energy. And when he steps in to the energy arena, it becomes clear that his expertise is on climate, not energy."43





4. P.A Kharecha and J.E. Hansen, 2013, 'Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power'. Environ. Sci. Technol., 47, pp.4889−4895,

5. 'Let the Facts Speak',


7. 'Chernobyl − how many died?', 26 April 2014, The Ecologist,

8. Dr Ian Fairlie, 16 Aug 2015, 'Summing the health effects of the Fukushima nuclear disaster',

9. Ian Fairlie, 2 April 2014, 'New UNSCEAR Report on Fukushima: Collective Doses',

10., p.183

11. Ian Fairlie, 27 Nov 2012, 'A 100 mSv threshold for radiation effects?',


13. BEIR VII − U.S. National Academy of Sciences, 2006, 'Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2',


15. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), 1994, 'Ionising Radiation: Sources and Biological Effects', New York: UNSCEAR,

16. Jusen Asuka, Seung-Joon Park, Mutsuyoshi Nishimura and Toru Morotomi, 31 Jan 2014, 'Reply to the letter from Dr. Hansen and others',


18. June 12, 2015, 'Nuclear Emergency Response Headquarters',




22. Kharecha, P. A.; Kutscher, C. F.; Hansen, J. E.; Mazria, E. 'Options for near-term phaseout of CO2 emissions from coal use in the United States'. Environ. Sci. Technol. 2010, 44, 4050-4062,




26. See pp.44-45 in Mycle Schneider, 2009, 'Fast Breeder Reactors in France', Science and Global Security, 17:36–53,

27. International Panel on Fissile Materials, 2010, 'Fast Breeder Reactor Programs: History and Status',

28. IRSN, 2015, 'Review of Generation IV Nuclear Energy Systems',

Direct download:

29. U.S. Government Accountability Office, July 2015, 'Nuclear Reactors: Status and challenges in development and deployment of new commercial concepts', GAO-15-652,

30. On the history of the integral fast reactor R&D program, see

31. Harold F. McFarlane, Argonne National Laboratory, 'Proliferation Resistance Assessment Of The Integral Fast Reactor',

32. George Stanford, 18 Sep 2010, 'IFR FaD 7 – Q&A on Integral Fast Reactors',

33. Nuclear Information & Resource Service, 'Nuclear-Free, Carbon-Free',

See also the NIRS 'Alternatives to Nuclear page' resources:

34. Article:

Report: 'China high renewables 2050 roadmap − summary',

35. WWF India and The Energy and Resources Institute, 2013, 'The Energy Report − India 100% Renewable Energy by 2050',

Summary: Emma Fitzpatrick, 17 Jan 2014, 'Even India could reach nearly 100% renewables by 2051',

36. See section 7 in: Jusen Asuka, Seung-Joon Park, Mutsuyoshi Nishimura and Toru Morotomi, 31 Jan 2014, 'Reply to the letter from Dr. Hansen and others',

Mark Z. Jacobson and Mark A. Delucchi, Nov 2009, 'A Plan to Power 100 Percent of the Planet with Renewables', Scientific American,

Mark Z. Jacobson and Mark A. Delucchi, July/August 2013, 'Meeting the world's energy needs entirely with wind, water, and solar power', Bulletin of the Atomic Scientists 69: pp.30-40,

WWF International, Ecofys and the Office for Metropolitan Architecture, 2011, 'The Energy Report: 100% Renewable Energy by 2050',

Greenpeace International, September 2015, 'Energy [R]evolution: A sustainable world energy outlook 2015',

A number of other useful reports are listed at the following webpages: (Global, Europe, America, Asia, Pacific, Others)

37. REN21 (Renewable Energy Policy Network for the 21st Century), 2015, 'Renewables 2015: Global Status Report',

38. Greenpeace International, September 2015, 'Energy [R]evolution: A sustainable world energy outlook 2015',


40. International Energy Agency, Oct 2015, 'Renewable Energy Medium-Term Market Report',

41. Jonathan M. Cullen, Julian M. Allwood, and Edward H. Borgstein, Jan 2011, 'Reducing Energy Demand: What Are the Practical Limits?', Environmental Science and Technology, 45 (4), pp 1711–1718,

42. Helen Knight, 26 Jan 2011, 'Efficiency could cut world energy use over 70 per cent',

43. Michael Mariotte, 9 Jan 2014, 'The grassroots response to Dr. James Hansen's call for more nukes',