Orion-style cargo launcher

You got your nuclear weapon. You stick that down in a hole. Has to be a real good hole. Maybe, say, lined with stuff. Lead. Sapphire-coated zinc oxide 'n' steel. Whatever. Really sturdy absorby stuff. You put your pusher plate on the top of the bomb. Plate fits right in the shaft, kinda. You put your stuff that you want to go up the gravity well on top of the plate, probly slather some of that absorbentonium underneath it on top of the plate as well as your shock absorbers on the nonbusiness (i.e. nonboom) side. You set the bomb off. Whomp, there goes your cargo. Hopefully she flies into orbit or whatever. The shaft, natch, is designed to seal itself off after "ignition," solving the problem of atmospheric debris, test ban treaties, etc. Do not hold in hand. Light fuse and get away. Put enough water or ice or whathaveyougel in your salt dome launchpad, use a low yield, might even be reusable... Come to think of it, the EMP from a nuclear blast could be used to trigger a big one-shot railgun, kind of, sorta. It's not better than Orion, just legal, international-treaty-wise...