The Australian Uranium Association estimated that it is economically viable at current prices to recover about 4.5 million tonnes of uranium, enough to satisfy the entire Earth's electricity demand if it were used by today's reactors, for less than 1,200 years. The situation isn't nearly so bleak, however.
In the United States, there are nearly 80,000 tonnes of 5%-used fuel, and more than 700,000 tonnes of depleted uranium left over from enriching mined uranium. A 1,700 GWe all-electric U.S. energy economy could be powered by this ``waste'' in fast-neutron reactors for 450 years, or longer depending upon use of renewable sources. Used fuel is significantly more radiotoxic than depleted uranium, so it should be consumed first. Every country that has nuclear reactors has stocks of used fuel and depleted uranium.
IFR extracts 99% of the energy immanent in mined uranium but today's reactors extract only 0.6%. The price of uranium would contribute the same cost to the delivered electricity price from IFR-type reactors if it were to increase 167 fold. Uranium could be economically extracted from lower quality ores, or from seawater, where there is estimated to be at least a thousand times more than could be extracted from land. Another low-quality ore is coal-fired power plant waste, which contains nineteen times more energy in the form of uranium and thorium than was extracted by burning the coal. Thorium, four times more common than uranium, can be converted to fissile fuel by neutron transmutation in a fast-spectrum reactor. Nuclear fission is an effectively inexhaustible source of energy.
Nuclear fission is an effectively inexhaustible source of energy
It is possible to breed about 5% more fuel from uranium than is consumed, but only about 1% more from thorium, so thorium should not be used before sufficient reactors are in service.
The first two goals of the IFR project were safety and waste mitigation. The third was fuel economy.