I have posted a number of articles about thorium. It is a radioactive element that some have suggested could replace uranium and plutonium in a new generation of reactors. Supporters say that thorium reactors would not be prone to meltdowns if cooling systems failed and they would not produce waste as dangerous as that produced by commercial reactors. India has huge reserves of thorium and has been working to develop commercial thorium reactors for decades. Other companies and countries have been actively researching and promoting thorium reactors for over fifty years. Recently there has been a backlash against the positive publicity in favor of thorium as the new and better source of nuclear power.
Thorium-232 has a half-life equal to the current estimated age of the universe – 14 billion years. Thorium is even more radiotoxic than uranium and plutonium. A given amount of radioactivity inhaled in the form of thorium compared to the same amount of radioactivity inhaled in the form uranium or plutonium results in a biological impact on bones over two hundred times as great. Thorium also produces daughter products that have half-lives of hundreds of thousands of years which means that spent thorium fuel must be stored for longer than spent uranium fuel.
Thorium cannot produce energy by itself. It must be mixed with weapons grade (ninety five percent pure) uranium or plutonium in order to produce energy. So even though thorium itself is safer than uranium or plutonium because it cannot be made into a bomb, in order to use it, bomb grade nuclear materials must be included. In addition, it would be easy to refine the uraium-235 in spent thorium fuel back to the level required for bomb production. Thorium reactor designs often utilize liquid sodium fluoride which is highly toxic and must be handled carefully. The high temperatures generated by experimental thorium reactors have damaged concrete structures containing the reactors.
Mining and milling thorium carries the same dangers as mining and milling uranium. Thorium breeder reactors have been built but they are not as efficient as uranium breeder reactors. In contrast to claims of more economical nuclear power from thorium, it turns out that the thorium fuel cycle is more complex and expensive than the uranium fuel cycle. In addition, the equipment and protective measures needed to handle thorium fuelare more expensive than what is required for the current types of nuclear fuel.
Thorium is much more abundant than uranium and would not pose a problem of supply. However, for all the other reasons detailed above, thorium is not the miracle fuel or the “green” nuclear alternative that it is purported to be. Despite aggressive promotion by trade associations such as the World Nuclear Association, thorium will never become a widely used nuclear fuel.
Diagram of thorium electron shells:
