Two workers were accidentally entombed inside the ballast tank of a nuclear submarine, it has been reported.
The electricians were mistakenly sealed into the tank at a Devonport base in Plymouth, where Britain’s nuclear submarines are refitted by contractor Babcock International.
A report said the submarine was in a dry dock last December and the two men were inside the ballast tank checking the sonar gear.
As they tried to leave they discovered that a seal had been placed over the entrance in preparation for an air tightness test.
The two workers hammered on the tank with a battery powered drill but nobody could hear them.
The report said: “They switched on their mobile phones but there was no signal at the bottom of the tank so they progressively climbed to the upper reaches of the tank until fortunately one phone managed to get a one bar signal.”
Twenty minutes after their ordeal started, the men were freed “shaken but unhurt”.
The Unite union said: “We feel for the men involved and what they had to go through because it must have been an extremely unpleasant situation.
“The incident was actually caused by poor management and poor communication.
“We are disappointed it was not in line with Babcock’s normal standards.”
Babcock said it was “continually focused on delivering and maintaining the highest standards of safety procedures and practices”.
It said an internal investigation was carried out and “changes to work control arrangements have been made”.
