(CNN) -- A fire last month aboard a U.S. nuclear submarine that caused more than $400 million in damage may have been caused by a vacuum cleaner, the Navy said Wednesday.
"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 Portsmouth Naval Shipyard Congressional and Public Affairs Office said in a news release. "Specific details as to the cause and subsequent damage assessment are still being evaluated as part of ongoing investigations and will be released at a later date."
Public Affairs Officer Deb White said she did not know what kind of vacuum cleaner had been implicated in the blaze or whether the same machine was used by any other nuclear submarines.
The May 24 incident affected the forward compartment of the USS Miami, where the crew's living quarters, command and control spaces and the torpedo room are, the release said.
"Miami's nuclear propulsion spaces were not affected by the fire," the release said. "The ship's nuclear propulsion plant was not operating at the time and the plant had been shut down for over two months. Nuclear propulsion spaces were isolated from the forward compartment fire early and spaces remained habitable, manned and in a safe and stable condition throughout the entire event. There were no torpedoes or other weapons onboard the submarine."
Cleanup in the forward compartment began last week and the Navy estimated an "initial rough repair cost" of $400 million, plus some 10% for what it called "secondary effects," including disruption to other planned work in the shipyards and the possible need to contract work to the private sector.
The submarine was commissioned in 1990 and carries a crew of 12 officers and 98 enlisted personnel, according to the Navy.