Yep, that's fair! But my understanding is the default behaviour of most nuclear weapons (other than Hiroshima-style ones) is "blows itself to pieces without de

Yep, that's fair! But my understanding is the default behaviour of most nuclear weapons (other than Hiroshima-style ones) is "blows itself to pieces without detonating the nuclear part", rather than "vapourises everyone within a mile". Everything needs to go right for a nuclear weapon to actually blow up with a significant yield.