The US Navy has lost/dropped some nuclear bombs too. But what he means is they've never had a serious reactor accident. They've lost two nuclear submarines,

The US Navy has lost/dropped some nuclear bombs too. But what he means is they've never had a serious reactor accident. They've lost two nuclear submarines, but neither was due to a problem with the reactor. Fumbling a nuclear bomb is obviously very concerning, but I don't think it reflects poorly on their ability to run reactors safely. They have several thousand reactor-years of safe operating experience, that doesn't happen by accident.