Change in radioactivity of an intermediate-level package
The radioactivity of ILW-LL is generally between one million and one billion becquerels per gram. The change in activity over time of an ILW-LL package, such as a container holding compacted 'cladding waste' from spent fuel reprocessing, follows the same general pattern as that of vitrified waste, but the initial activity level is obviously lower. The average thermal output of this type of waste is initially about twenty watts per waste package but it decreases by a factor of 10 over a century.