The UK Royal Navy’s nuclear-powered submarine, HMS Triumph, has begun sea trials after completing a major six-year refit programme.

During the £300m ($451.8m) refit, the submarine underwent capability improvements, which included installation of the latest sonar systems and an upgrade for the Tomahawk land attack cruise missile system.

The refurbishment work also included the installation of a new command and control system, and a new internal fibre-optic computer systems network and enhanced satellite communications system.

Additional enhancements include the installation of a ballast pump to aid rapid deballasting, as well as a number of safety improvements for firefighting and escape capabilities.

The extensive sea trials will continue for a three-month period to ensure the modifications made to the propulsion and command systems withstand the demanding environment at sea both on the surface and at depth.

The refit work for the submarine was carried out by the Royal Navy in cooperation with Babcock.

The last Trafalgar Class submarine is scheduled to be delivered to the Royal Navy in 2011.