Serious procedural failure in Trafalgar class nuclear submarine maintenance

It has emerged during routine maintenance work on two of the UK’s six remainingTrafalgar-class attack submarines – Turbulent and Tireless – that equipment that blocked hull valves , used during during earlier maintenance to test hull pressure for leaks – was not removed after the tests.

The purpose of the valves is to allow an build up of excess pressure in the ship’s nuclear reactor, to vent. Obviously, with the blocks left in place, venting is impossible and excess pressure could then lead to radioactive water bursting into the manned areas of the ship.

This unchecked procedural fault left both submarines at sea for extended periods on active operations – unknowingly at risk of  a serious accident with crews exposed to radioactive contamination. Turbulent remained at sea for over two years and Tireless for over one year with this block in place in each ship.

There were several intermediate occasions when this obstruction should have been discovered and removed and was not.

During this period of risk, HMS Turbulent visited Faslane in Argyll, among other ports.

Turbulent was the second of the seven Trafalgar class submarines to be built and commissioned (1984) with Tireless following her down the slip, commissioned in 1985. Both are based at Devonport where it is understood the faulty procedure took place.

Both will eventually, as elderly ships, be relocated to Faslane, with the Argyll naval base becoming the UK national submarine base.

The Trafalgar class has suffered from a series of technical difficulties and at one point, in August 2000, only one of the seven was at sea with the others in extended refit.

The first of the class, Trafalgar, commissioned a year before Turbulent, has already been decommissioned, in 2009. She had a lively life in her later years, as the submarine that famously collided with the Isle of Skye during Operation Cockfight (an officer training exercise) in 2002.

HMS Tireless experienced a small onboard explosion in In 2007 while she was submerged under the Arctic icecap during a joint British-American exercise. Two sailors died and another was injured. An  out of date oxygen candle in the forward section has been identified as the probable cause.

The Trafalgar-class submarines and the Swiftsure-class submarines will be replaced in operational function by the new advanced attack submarines, the Astute class.

Class leader Astute , delivered very late and well over budget (such is the MoD’s normal track record on defence procurement contract management), has already been at Faslane, her base to be – and is undergoing sea trials.