The Royal Navy's nuclear-powered hunter-killer submarines have been withdrawn from service after the discovery of a potentially generic flaw in some of the welding on the pipework of the reactor cooling system.
The flaw first appeared as an external leak from a weld on HMS Tireless. During repair operations, the pipe was drained, and it was found that the failure method implied that there may be a generic problem.
The cause of the problem has not yet been identified. Jim Jenkin, an MoD spokesman, said that, to date, only HMS Tireless had shown this defect. He was unable to say how long the inspections would take. He was able to confirm that the Vanguard class of Trident submarines are not affected by the potential flaw.