In the aftermath of the USS Miami fire, all of the public shipyards have been told to empty industrial style shop vacuum cleaners each shift or remove them from the ship.

Fire safety and fire fighting response inspections have been conducted on ships, with particular attention paid to temporary services and the stowage of combustible materials on board, officials at the Portsmouth Naval Shipyard said Friday. The Navy is reviewing the models of vacuum cleaners used on ships and will say what models are authorized by the end of June.

Preliminary findings show that the fire that caused more than $400 million in damages to the submarine started in the vacuum cleaner used to clean the work site at the end of a shift, the shipyard said earlier this week.

The shipyard said the vacuum was not plugged in or defective. The fire apparently started with a heat source being vacuumed up and igniting the debris in the vacuum cleaner, the shipyard said.

Electric Boat could not say whether it has changed its practices for how vacuum cleaners are used and stored there, due to the ongoing investigation, but did say the company “takes all appropriate measures to ensure the safety and security of the workplace.”

The Miami (SSN 755) was in a dry dock at the Portsmouth Naval Shipyard for maintenance and upgrades when it caught fire at 5:41 p.m. May 23 and burned until 3:30 a.m. the next day.

The fire damaged the torpedo room, command and control spaces and berthing areas. The reactor had been shut down for more than two months at the time of the fire, and the nuclear propulsion spaces were not affected, according to the Navy. No weapons were on board.

The Navy has estimated repairs to the sub at about $440 million, or a base of $400 million plus 10 percent due to the disruption of other planned work across all naval shipyards and the potential need to contract with the private sector. It will be repaired at the naval shipyard, according to the Navy.

j.mcdermott@theday.com