|Successive periods of dominance...|
This simplified waste consists of six radioelements that are present in the spent fuel of a reactor. The 'pies' show the contribution of the six elements to the activity of this imaginary waste at the outset and 5, 50, 500 and 5000 years later. Each of these points in time is characterised by the dominance of one particular element. Initially, iodine-131 is the dominant element. After 5 years, the iodine-131 has disappeared and caesium-134 is dominant, and so on until technetium takes its turn after 5000 years. In the meantime, the activity has decayed considerably. It will be millions of years before the uranium becomes the dominant element, despite the fact that it accounts for almost all of the mass.