It's amazing that over 40 years after the 1963 Nuclear Test Ban treaty effectively killed any hope of nuclear detonation propulsion (and the 1967 Outer Space Treaty didn't help either) that people still hang on to this long dead dream. It isn't going to happen.

Before the Test Ban Treaty, the US military did at least two nuclear detonation tests in space. At least one of them caused widespread blackouts over the Pacific rim, leading to our understanding of EMP effects. They reportedly also increased the background radiation levels of space leading to the premature death of one of Britain's first satellites. An Orion-style project using conventional nuclear detonations would likely cause widespread EMP damage and would quite likely pollute near Earth space something awful. The vulnerability of modern electronics is far worse today than it was in the early 1960s. Most things still used vacuum tubes back then and they were much more robust than integrated circuits to power surges. I doubt if electrical power systems are significantly more robust today than they were back then, either.