@cicerone imposter,
Your info is out of date. We have reduced the inventoiry of our nuclear weapons by half under treaties signed over a decade ago. Most of those eliminated were so-called "tactiucal nukes" artillery shells and lightweight (< 2,000 lbs) bombs for tactical aircraft.
There have, as you say, been no accidental detonations of operational weapons, but there have been a number of so called "criticality events" in weapons labs, including a few involving enriched uranium in which criticalitry among the prompt neutrons alone was achieved. One involved the prototype plant for the USAF nuclear powered ( a somewhat nutty idea now) aircraft at the Idaho laboratory in which several workers there were killed.