Actually, Plowshare succeeded in it's practical applications. They wanted to dig big holes fast, and by god they did. That was when the indirect costs of applying the technology (namely, poisoning the world) became apparent and it was prudently abandoned.

I would use effective to describe what you are talking about. If it were practical, the utility would exceed the indirect costs.

That's a fair statement.

Isn't radioactive fallout a direct cost of the technology?

As maxerickson pointed out, that's true, and I acknowledge the defect in my argument.