Thorium for nuclear energy - a proliferation risk?

Thorium is a potential nuclear fuel for future power plants. Especially in India and China research on Thorium driven reactors is performed since the world wide deposits of Thorium are much larger than those of Uranium. Particularly India has large Thorium deposits but only limited Uranium ore resources. Furthermore, depending on the reactor design, less of problematic minor actinides will be produced. During reactor operation the fertile Thorium is converted into the Uranium isotopes U-233 and to a small extent the highly radioactive U-232. The fissile U-233 may be diverted to build a nuclear weapon without further enrichment. This poses a high proliferation risk on the use of Thorium. The high radiotoxity from U-232 and its daughter products might form an effective internal safeguard barrier that prevents the easy use of U-233. Thorium reactor concepts will be presented and existing safeguards measures as well as their preferable expansion are discussed.