A fire that caused an estimated $400 million in damage to a U.S. Navy nuclear-powered submarine docked in Maine may have been caused by a vacuum cleaner, authorities said on Wednesday.
The fire in the forward compartment - which includes crew living, command and control spaces and the torpedo room - of the USS Miami on May 23 took about 12 hours to extinguish and injured seven firefighters.
"Preliminary findings indicate the fire started in a vacuum cleaner used to clean work sites at end of shift, and stored in an unoccupied space," the shipyard's public affairs office said in a release. Specific details are still being evaluated.
Initial conclusions reached through a formal Naval safety investigation could be released in the next two weeks.
The Miami's nuclear propulsion plant was not operating at the time and had been shut for over two months. The nuclear areas were isolated from the fire early.
No torpedoes or other weapons were on board the submarine, which was at the Portsmouth Naval Shipyard in Kittery, Maine, three months into a planned 20 months of maintenance.
The Miami is worth an estimated $900 million. The Navy estimates the repair cost at $400 million, plus another 10 percent for secondary effects such as disruption to other planned work at naval shipyards and the potential need to contract work to the private sector.
Workers at the Portsmouth shipyard returned to work in the forward compartment last week to start cleaning up and helping with damage assessment. The Navy is seeking bids on other cleaning contracts.