The nuclear fuel cycle consists of the process of mining and milling of uranium, conversion to fuel material, usually including enrichment in the isotope U-235, fabrication of fuel elements, utilization of the fuel in nuclear reactors, reprocessing of spent fuel and recycled utilization of recovered fissile materials, transportation of material between fuel-cycle installations, and disposal or radioactive wastes. Almost all the radioactivity associated with the fuel cycle is present in stored, spent fuel elements and in well contained fractions separated from the fuel during the reprocessing operations. However, at each step of the fuel cycle, releases of small quantities of radioactive material into the environment may occur, although these are only of local or regional concern because their half-lives are short compared to the time required for dispersion to greater distances. Some radionuclides, on the other hand, having longer half-lives or being more rapidly dispersed, can become globally distributed. In addition to the small releases of radioactive material during normal operation the possibility exists that additional amounts of radioactive materials may be accidentally discharged.
The problems of the proliferation of nuclear power include the disposition of long-term radioactive waste ('long-term' being without precedent in recorded human history - the half-life of plutonium-239, a significant and inevitable by-product of nuclear reactors, is 24,000 years); the location of power reactors in regards to surrounding human populations and the preparation for emergencies associated with accidental radioactive releases; and the ecological impacts from the use of salt, clay, and hard rock geological formations.
The Soviet nuclear disaster at Chernobyl is thought to have occurred through a blunder by the reactor's operators. Many have died as a direct result of the accident, many thousands more will die prematurely of cancers and birth defects induced by the radioactivity released there. A very large area of the former Soviet Union has been severely contaminated, economic damage to the former Soviet Union and surrounding countries is immense. Data from Chernobyl indicates that at least 30% and probably more than half of the reactor's inventory of radioactive isotopes of caesium and iodine were released. The total installed nuclear electric generating capacity in the world in 1976 was 79.8 GW from 188 reactors operating in 19 countries. The predicted capacity for the year 2000 is 2000 GW.
As of 1981, there either existed, were in a state of construction, or were in advanced planning, 762 nuclear reactors spread throughout 42 countries. The most significant number of reactors include the USA with 174, USSR 73, France 70, Germany 53, UK 44, Japan 43, Canada 28, Spain 18 and Sweden 12.
The net impact of Chernobyl is to make nuclear power very much safer throughout the world. Fission power should not be permanently removed from the array of energy-mobilizing options for the future. It is quite possible that reactors that are sufficiently resistant to catastrophic accident and sabotage can be designed, built and operated, and that satisfactory methods for disposing of nuclear wastes can be developed.
The extensive use of nuclear power may prove to be the most effective way of diminishing the risk of global warming by reducing the use combustion of fossil fuels that release carbon dioxide.