More scare stories!
No basis in physics for waiting? The physics I took says that radioactive elements decrease in intensity and potency with time, as they give off their radioactivity. Every radioactive element eventually results in non-radioactive lead, through a long chain.
Waiting years will decrease the potential exposure to workers. Poor practices could still result in overexposure, but nothing lethal.
Whatever radioactive material is in the ground will be moving toward the river, but also decaying, thus decreasing in intensity. After years, it will be below safe levels.
Wanting to clean up more than below safe levels is a political tactic. But then, what can you expect from someone who said in a WCAX interview that the used fuel is on the roof?