Evolution of the heat released by a standard vitrified HLW waste package.
A 200 liters package of vitrified waste gives off 3000 W when produced at the La Hague plant, 700 W after 35 years, 170 W at 100 years and less than 30 W at 300 years. In terms of years, the decrease of the heat release is slow, but at the scale of several decades or centuries it becomes important. During the first century, the contributions of two short-lived fission products, caesium-137 and strontium-90 (in red and blue), are predominant.
IN2P3 (Source: National Assessment Board)