HMS Vigilant of the UK Royal Navy has been successfully refuelled by Babcock under the two-year long overhaul period (refuel) (LOP(R)) programme.
The third Vanguard Class nuclear submarine has been refuelled with Core H, to provide power for the rest of the vessel's operational life.
The project, carried out at Devonport Royal Dockyard, involved a major revalidation of all reactor systems and replacement of major equipment.
Babcock submarine programme director Gavin Leckie said the completion of the refuel indicates the beginning of the final phase of the LOP(R) programme.
The final phase involves commissioning of submarine systems and reinstating the submarine structure for flood-up in summer 2011.
The LOP(R) programme is expected to complete in 2012 after sea trials of the submarine.