McKenna, Phil. "Is the "Superfuel" Thorium Riskier Than We Thought?" Popular Mechanics. N.p., 30 Jan. 2015. Web. 04 Sept. 2016. <http://www.popularmechanics.com/science/energy/a11907/is-the-superfuel-thorium-riskier-than-we-thought-14821644/>.
"It may not be as resistant as touted and in some cases the risk of proliferation may be worse than other fuels," says Stephen Ashley of the University of Cambridge. In an article published in the journal Nature online today, Ashley and his colleagues highlight the potential dangers of thorium fuel.
When thorium is irradiated, or exposed to radiation to prepare it for use as a fuel in nuclear reactions, the process forms small amounts of uranium-232. That highly radioactive isotope makes any handling of the fuel outside of a large reactor or reprocessing facility incredibly dangerous. The lethal gamma rays uranium-232 emits make any would-be bomb-maker think twice before trying to steal thorium
But Ashley and his co-authors say a simple tweak in the thorium irradiation recipe can sidestep the radioactive isotope's formation. If an element known as protactinium-233 is extracted from thorium early in the irradiation process, no uranium-232 will form. Instead, the separated protactinium-233 will decay into high purity uranium-233, which can be used in nuclear weapons.
"Eight kilograms of uranium-233 can be used for a nuclear weapon," Ashley says. "The International Atomic Energy Agency views it the same as plutonium in terms of proliferation risk."