The table below is an updated version of a similar table in IEER’s report, The Nuclear Power Deception (1996), which has more information on nuclear reactors and reactor accidents.

Nuclear Reactor Accidents

Reactor type Location Accident type Year Iodine-131 release, curies Comments
Light water reactor, BWR Fukushima, Japan Cooling system failure, hydrogen explosion 2011 2.4 million (as of March 25, 2011)
Sodium-cooled fast breeder Monju, Japan major secondary sodium leak 1995 secondary sodium was not radioactive; reactor was in test phase; extensive sodium contamination in plant
Heavy water moderated and cooled, CANDU type Narora, Uttar Pradesh, India turbine fire; emergency core cooling system operated to prevent meltdown system 1993 apparently no release of radioactivity
Graphite-moderated, water cooled Chernobyl, Ukraine supercriticality, steam explosion and graphite fire 1986 7 million, perhaps far greater (see text) Safety experiment went awry; total release 50 to 80 million curies or more; potential for continuing large releases exists
Light water reactor, PWR type Three Mile Island, near Harrisburg, U.S. cooling system failure, partial meltdown 1979 13 to 17 secondary containment prevented release of millions of curies of I-131; accident developed over several hours
Sodium-cooled fast breeder Lagoona Beach (near Detroit) U.S. cooling system block, partial meltdown 1966 release confined to the secondary containment reactor was being tested for full power, but did not reach it; four minutes from indication of negative reactivity to meltdown
Light water reactor, BWR near Idaho Falls, U.S. accidental supercriticality followed by explosion and destruction of the reactor 1961 80 small U.S. Army experimental reactor using HEU fuel; 3 operators were killed
Heavy water cooled and moderated reactor Chalk River, Canada lack of coolant for a fuel element 1958 radioactivity apparently contained within building Highest worker dose 19 rem
Graphite-moderated, gas-cooled Sellafield, Britain graphite fire 1957 20,000
Heavy water moderated, light water cooled, experimental reactor Chalk River, Canada inadvertent supercriticality and partial meltdown 1952 “There was some release of radioactivity” President Jimmy Carter helped in the clean-up

Full references for the original table are available in IEER’s report Nuclear Power Deception.