Well, it depends on when you go about doing that study. The waste may be sitting in storage for over 20-25 years or more. If you don't look at it every day to see what the radioactive content is, when you go back to do that study, you would find that it has reduced in its radioactive content.
That could lead to a change in the inventories that are available. That's what's really important. The radioactive waste does not stay stable in the way it is today. It will decay over time. It will be less as you go forward.