There's nothing interesting (e.g. terrorism, bombs) you can do with nuclear waste, and it's not especially poisonous.
If you just loaded it up in barrels and dropped it at the bottom of the ocean, what's the worst that could happen?
Sure, some fish would die, but where are the millions of deaths?
LOL. Nuclear materials, including waste, are extremely dangerous in evil hands. It regularly kills people by accident or due to negligence. Chornobyl was an accident. Just imagine what a team of motivated people with evil intent can do with a nuclear station or nuclear waste. Last attempt to use nuclear waste in war was in 2015: Russia-backed terrorist planed to use radioactive waste (Kyshtym) to throw a dirty bomb at Kyiv.
Most waste is processed so its for example sealed into some kind of material prior to burial. So recovery of the radioactive portion, concentrating and refining it etc would be a pretty major undertaking.
You may also be confusing the long radiation stuff with high radiation stuff.
There's an inverse relationship here with the half-life. The most dangerous waste is stuff that burns up in a few decades, the type that lasts for millions will emit very little radiation per unit time.