Orion is a really cool concept and it's a lot of fun to think about, but realistically any space propulsion system that horribly contaminates the atmosphere and fries every satellite anywhere near Earth is not an option.
It's not really useful for the type of spacecraft we use today, but if you assemble the spacecraft in orbit and only use the nuclear propulsion once you are far enough away from satellites it looks great for gigantic payloads or very high speeds.
You lose much of the advantage of Orion, since Orion is extremely heavy, and you're doing the hardest part of the work without it. You also have to wait until you're pretty far away from Earth, not just out of the atmosphere, before you start blowing up nukes unless you want to destroy all electronics in sight.
>any space propulsion system that horribly contaminates the atmosphere
Modern nukes are very clean. Even in the 70s, we had nukes that were up to 98% efficient. I can't find the numbers for newer bombs, but they are even cleaner.
High efficiency just means you're not leaving lots of uranium and plutonium behind. You're still leaving lots of fission products, and lots of neutron-activated materials from the non-nuclear components of the bomb.
There's a reason that testing nuclear devices in the atmosphere is frowned upon these days.
