Wednesday, 30 October 2013

Hans Blix - Thorium can reduce the risk of nuclear proliferation

In his presentation to the Thorium Energy Conference - ThEC13 in Geneva on 29th October 2013 Hans Blix stated that it is time for the nuclear power industry to move away from using uranium as its primary fuel towards thorium.

“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 civilian nuclear community must do what it can to help reduce the risk that more nuclear weapons are made from uranium or plutonium.  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.”

Thorium is a better fuel
Blix described the obstacles that are in the way of a shift to thorium and other nuclear alternatives as “political” rather than “technical.”  He compared using uranium in civilian nuclear power stations to the use of propeller driven planes which, "although they’ve served us well and continue to do so, have in general given way to a better technology, the jet plane".  He went on to describe other advantages that burning thorium brings, such as less nuclear waste which doesn't remain radioactive as long. It is also at least three times as abundant as uranium.

Hans Blix is known globally as the former United Nations chief weapons inspector at the time of the second Gulf War. 

Between 1981 and 1997 he headed the International Atomic Energy Agency so he understands the technical issues.

Not everyone agrees that thorium reactors are totally without proliferation risks since they require a start-up charge of enriched uranium or plutonium, but it’s very encouraging that someone like Hans Blix is promoting the advantages of thorium as a nuclear fuel and specifically because there is less risk of proliferation. 

Operation Teapot
Inside the breeder version of a thorium reactor fertile thorium-232 is converted to fissile uranium-233. Despite the ease of manufacturing uranium-233 from abundant natural thorium there has only ever been one operational nuclear weapon that has used uranium-233 as its fissile material. It was part of an American test series in 1955 called “Operation Teapot”.

When uranium-233 is used as a nuclear fuel, however, it is inevitably contaminated with uranium-232, which decays rather quickly (78 year half-life) and whose decay chain includes thallium-208, a “hard” gamma emitter. This makes any uranium contaminated with uranium-232 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. For the bomb test uranium-233 with very low uranium-232 contamination was generated in special reactors at Hanford, but it cannot be produced in reactors that use the uranium-233 as fuel.