So basically unless it was manufactured within the last 15 years it would require alot of maintenance and would produce a highly radioactive
enviroment and need a secure containment facility to conduct the maintenance in, right ?
Otherwise you would have this really bright hot spot of radioactivity that we could home in on and discover traces of the weapon.
So the biggest threat that any of these "missing" nukes could present would be a "dirt bomb" and maybe have an explosive magnitude of 5-10 tons
(guessing if the high energy component was decayed)


