Routine Releases of Radioactivity from the Nuclear Industry

Abstract

A light-water reactor consists of long, thin rods (fuel pins) of uranium oxide (UO₂), enriched to about 3% in ²³⁵U, submerged in water. In the proper geometry, this arrangement permits a chain reaction in which a neutron striking a ²³⁵U nucleus induces a fission reaction, which releases neutrons some of which induce other fission reactions, etc. Each fission reaction releases energy, which is rapidly converted to heat, warming the surrounding water. The reactor therefore serves as a gigantic water heater; as water is pumped through at a rate of hundreds of gallons per second, it is heated to 600°F. The hot water may then be converted to steam either in the reactor [boiling-water reactor (BWR)] or in an external heat exchanger called a steam generator [pressurized-water reactor (PWR)]; the steam then drives a turbine, which turns a generator to produce electric power.