Posted by Mark Halper

Hans Blix CERN THEC13

Thorium on his mind. Hans Blix says it’s time for the nuclear industry to move away from uranium.

GENEVA – Hans Blix, the disarmament advocate who famously found no weapons of mass destruction in Iraq a decade ago, said today that thorium fuel could help reduce the risk of weapons proliferation from nuclear reactors.

Addressing the Thorium Energy Conference 2013 here, Blix said that nuclear power operators should move away from their time-honoured practice of using uranium fuel with its links to potential nuclear weapons fabrication via both the uranium enrichment process and uranium’s plutonium waste.

“Even though designers and operators are by no means at the end of the uranium road, it is desirable today, I am convinced, that the designers and the others use their skill and imagination to explore and test other avenues as well,” Blix said.

“The propeller plane that served us long and still serves us gave way to the jet plane that now dominates,” said the former United Nations chief weapons inspector who also ran the International Atomic Energy Agency from 1981 to 1997. “Diesel engines have migrated from their traditional home in trucks to a growing number of cars and cars with electric engines are now entering the market. Nuclear power should also not be stuck in one box.”

Blix rattled off a list of thorium’s advantages, noting that “thorium fuel gives rise to waste that is smaller in volume, less toxic and much less long lived than the wastes that result from uranium fuel.” Another bonus: thorium is three to four times more plentiful than uranium, he noted.

“The civilian nuclear community must do what it can to help reduce the risk that more nuclear weapons are made from uranium or plutonium,” Blix said. “Although it is enrichment plants and plutonium producing installations rather than power reactors that are key concerns, this community, this nuclear community, can and should use its considerable brain power to design reactors that can be easily safeguarded and fuel and supply organizations that do not lend themselves to proliferation. I think in these regards the thorium community may have very important contributions to make.”

Blix described the obstacles that are in the way of a shift to thorium and other nuclear alternatives as “political” rather than “technical.”

Not everyone agrees that thorium is a proliferation cure for the nuclear power industry. Even some supporters of thorium note that thorium fuel cycles yield elements such as uranium 233 that groups could use to make a bomb if they were able to get a hold of it.

The lively discussions surrounding these and other thorium issues will continue tomorrow at the conference, which is taking place at CERN, the international physics laboratory. Earlier at the gathering today, conventional nuclear giant Areva announced a thorium collaboration with Belgian chemical company Solvay. Yesterday, Nobel prize-winning physicist Carlo Rubbia lauded thorium for its “absolute pre-eminence” over uranium.

Photo of Hans Blix by Mark Halper


  1. John Preedy says:

    It’s great that someone whose name is known globally is promoting the advantages of thorium as a nuclear fuel and specifically because there is less risk of proliferation. Inside the breeder version of a thorium reactor thorium is converted to 233U. There has only ever been one operational nuclear weapon that has used 233U as its fissile material, despite the ease of manufacturing 233U from abundant natural thorium. It was part of a test series in 1955 called “Operation Teapot”. When 233U is used as a nuclear fuel, it is inevitably contaminated with 232U, which decays rather quickly (78 year half-life) and whose decay chain includes thallium-208. 208Tl is a “hard” gamma emitter, which makes any uranium contaminated with 232U nearly worthless for both official and clandestine nuclear weapons since the gamma radiation would damage electronics and is easily detected because of its unique signature. 233U with very low 232U contamination could be generated in special reactors like Hanford, but not in reactors that use the 233U as fuel.

    • Nicholas Thompson says:

      Yes, U233 in thorium reactors is contaminated with U232, just as in normal reactors with a high burnup, Pu239 is contaminated with Pu240, 241 and 242. At least in any US reactor, the Pu239 is not of high enough quality to build a weapon. The problem comes in when a reactor is only run with a very short burnup, in this case high purity Pu239 can be produced.

      That said, thorium reactors are no less proliferation resistant. Many people have been calling for liquid fluoride fueled thorium reactors, which could have onboard reprocessing technology. In such a reactor, if protactinium can be seperated from uranium and thorium as the reactor is operating, then a batch of Pa could be set aside for two weeks. After that 2 weeks, the Pa232 and Pa234 would have undergone over 10 half-lifes of decay (decaying to U232 and U234), leaving only Pa233. If this uranium is separated again from the protactinium, what will be left is almost pure Pa233 which will decay to almost pure U233. For more information on this, there is an article in Nature (

      In both cases (U235 and thorium reactors), it is necessary to have the technology to separate actinides. No difference in proliferation resistance.

      There are other arguments to use thorium over U235, but this isn’t one of them.

  2. Jack K says:

    The Thorium Fuel Cycle, An independent assessment by the UK National Nuclear Laboratory. “It is estimated that it is likely to take 10 to 15 years of concerted R&D effort and investment before the Thorium fuel cycle could be established in current reactors and much longer for any future reactor systems… the thorium fuel cycle does not currently have a role to play in the UK context… the benefits of the thorium fuel cycle have been over-stated.”

    But if the former head of the IAEA says thorium nukes are the solution to all our problems then it must be true.

  3. Mark Pawelek says:

    I don’t think we can roll out thorium nuclear power planet-wide and keep non-proliferation targets. Is someone proposing that every nuclear power plant be monitored (or run) by the UN or powers-that-be? Is so, what of those nations who’ve not signed the treaties? – India and Israel spring to my mind.

    It’s been argued that a bomb can be made from U-233, even if it can’t be, very similar technology (the same?) to thorium fast breeders can be used to breed Pu-239 from U-238. That’s a 2nd arrow the non-proliferation advocates will put in their bow.

    I say, let’s consider the main problem: AGW (an existential threat), the main remedy (energy cheaper than fossil fuel), get the technology working ASAP, roll it out, then live with the consequences.

    Great to have Hans Blix on board the good ship thorium power.

    • Vishal says:

      there were none. Many were dumbfounded by the deiiocsn. But deiiocsn it was and deiiocsn it stood and stands That deiiocsn was the start of the refusal to scuttle the thunder of lies directed at the Bush Administration thereafter, the lies Rove has written saying he regretted not answering, and continues not answering, belying his “regret.”

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