ABSTRACT
Nuclear power can use two naturally occurring elements, uranium, and thorium, as the sources of its fissioning energy. Uranium can be a fissionable source (fuel) as mined (Candu Reactors in Canada), while thorium must be converted in a nuclear reactor into a fissionable fuel. Uranium is present in the earth's crust to the extent of four parts per million. This concentration makes uranium about as plentiful as beryllium, hafnium, and arsenic; and greater in abundance than tungsten, molybdenum, and tantalum. The major countries with reserves of uranium in order of importance are Australia, United States, Russia, Canada, South Africa, and Nigeria. Once the uranium ore is mined it is sent to a concentrator (mill) where it is ground, treated, and purified. Since the ore is of a grade of 0.1"–0.2" uranium, a ton of ore contains only between 1 and 2 kg of uranium per 1000 kg of ore.
