We’ve never really seen Godzilla’s atomic breath interpreted as a closer ranged, concussive and explosive, shotgun-like force before. Could be an awesome idea.
The Godzilla puppet refused to stop vaping, despite being told repeatedly it was prohibited on set. He was fired by Toho after production wrapped, and replaced in future films by his cousin Mortimer.
As the creature grows, I think it frequently hacks up oily goop from the spill, which it can ignite almost like napalm. Later, this precedes the atomic breath almost like "flushing out the pipes" before the pure white flame develops.