What is a canister of HLW?

The vast majority of the radioactivity associated with nuclear electricity production is due to the fission products created in the reactor, and contained in the spent fuel.

These fission products have no possible use and are managed as High Level Waste (HLW). Through reprocessing, these fission products together with traces of other final waste, are "vitrified", that is to say incorporated into a borosilicate glass for their definitive immobilisation and confinement in a form suitable for final disposal.

An international consensus recognises borosilicate glass as the best adapted and most stable matrix for these wastes. This constitutes the vitrified residues which, in a compact volume, represents 99% of the total radioactivity of the various waste sorted out by the reprocessing operations.

The canister is a stainless steel cylinder 1.340 m in height and 0.430 m in diameter, containing 150 litres (400 kg) of solid glass, with a percentage of 14% of fission products corresponding to the reprocessing of around 1.3 tonne of spent fuel on average.

The thermal output of each canister to be returned is comparable to a typical household radiator.

The specifications of the glass produced by the COGEMA La Hague reprocessing plant have been approved by the French Safety Authorities and confirmed by the governmental Authorities of Japan, Germany, Belgium, Switzerland and the Netherlands.

French two-stage continuous vitrification process
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Destorage and loading operations
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Release: December 1998