The good thing about nuclear waste, is you aren’t breathing it in. You can just bury it and kinda forget about it.
The most radioactive stuff decays quickly, so it won’t be dangerous for generations to come. The less radioactive stuff can last millions of years, but the amount of radiation it creates is too small to be harmful (with the proper precautions).
Quickly is around 100 000 years. Konrad mine, Asse II mine, WIPP are here to remind that it is not simple.
The engineers who say there is no risk are the same ones who recommended dumping nuclear waste into the sea in the 1960s and 1970s.
I was thinking more like 30 years. With a 100 000 years half-life, the radiation amount should be small enough not to be a problem.