|Heat from a container of vitrified waste|
Containers of vitrified waste from the nuclear industry are too recent to have had time to age. They still emit excessive heat caused mainly by the decay of fission products contained therein. At the age of 5 years, the short-lived fission products contribute about 90% of the heat release and the minor actinides (americium and curium) for only 11%. At age 35 the heat of 2350 watts fell to 700 watts, two products of fission - Cesium-137 and strontium-90 - alone emit 84% of this heat.