Don't forget that those casks are really heavy. If you launch the "waste" into space in them you'll be launching a lot more mass than just the 30kt. I don't know the exact ratio between cask mass and waste mass, but it could easily be 10:1.
Also, I'll repeat that throwing away valuable nuclear material just because it's called a "waste" product is stupid. Paying a lot of money to throw it into space is even dumber.
I think they are referring to fast reactors (Referring to the fast neutrons used to induce fission) that can burn high level nuclear waste from standard PWR plants as fuel.
Also, I'll repeat that throwing away valuable nuclear material just because it's called a "waste" product is stupid. Paying a lot of money to throw it into space is even dumber.