The Bethesda Japan website update was spotted by Kotaku. In editing the Japanese release, the "The Power of the Atom" side quest was modified to disallow actually triggering a nuclear weapon, and the non-player character Mr. Burke has been removed from the game entirely.
Additionally, a weapon has had its name changed for having a name deemed "inappropriate" for Japanese audiences. Bethesda does not specify which weapon has been renamed, but the smart money is on the Fat Man mini-nuke launcher, named after the nuclear bomb dropped on Nagasaki.
Bethesda also made clear that violent content, such as gore, blood, or dead bodies, has not been lessened in comparison to the North American release.