‘Stop work’ notice issued following safety concerns during refit work on nuclear powered submarine HMS Trenchant at Devonport dockyard

Concerns about emergency response arrangements resulted in a 'stop work' notice being issued for refit work on a nuclear powered submarine at Devonport naval dockyard earlier this year, according to a report published by the government's nuclear safety regulator.

The latest quarterly report issued by the Office for Nuclear Regulation (ONR) for the Devonport dockyard mentions two incidents which took place at the dockyard earlier this year during refit work on the nuclear powered submarine HMS Trenchant, currently at Devonport for a two year Revalidation and Assisted Maintenance Period (RAMP) overhaul.

The first of the incidents occurred when a flood alarm indicated that water was entering the dry dock in which Trenchant was berthed.  Devonport Royal Dockyard Ltd (DRDL) – the private sector company which operates the dockyard on behalf of the Royal Navy – was alerted and asked to deal with the situation but “did not provide the appropriate support in a timely manner”, although the issue was eventually resolved.  Three days later a second incident occurred when the submarine's fire alarm sounded.  The emergency access route to the site was not open to firefighters, extending the time needed for them to reach the submarine.

The events raised concerns about the effectiveness of on-site emergency response arrangements, and a 'Safety Stand Down' was enforced on the dockyard's Submarine Refit Complex, placing a 'stop work' notice on all hot work and all work on submarines in dry dock.  DRDL is formally investigating both events and ONR is carrying out “appropriate information gathering activities” to establish what lessons should be learnt.

ONR is currently investigating another incident which took place earlier this year involving the unauthorised movement of a 'Chacon' temporary container store for radioactive material from HMS Trenchant.  According to ONR, the incident involved “a loss of control” of contaminated waste material.  Although there were no radiological consequences from the event, DRDL is undertaking an investigation into the incident and ONR and the Environment Agency will consider whether to take regulatory action in the light of the findings of the investigation.

Submarine maintenance work at Devonport remains under close supervision by ONR, with each refit docking requiring specific permission from the regulator.  Despite the work currently underway on HMS Trenchant in 15 Dock, ONR has stated that “there are further improvements still to be implemented” and “recommendations from assessments to be resolved” before DRDL, a subsidiary of the Babcock International Group, will be granted permission for the next docking.  The regulator has advised that engineering improvements will be required for a dockside crane before any further dockings are allowed.

ONR has also asked DRDL to bring their arrangements for managing human resources in relation to nuclear safety – a matter which has been “of long-standing regulatory interest” to the regulator – into line with modern good practice within the nuclear industry.  This is expected to require “a sizeable amount of work” and DRDL has been set an “expectation” that improvements will be made within eighteen months.

The regulator has also raised concerns with DRDL about leadership and management for safety at the site, having identified “some shortfalls against the expectations of ONR guidance”, and  is working with the company to establish ways of addressing the issues.  ONR  is also seeking “further improvements” to arrangements for  examination, inspection, maintenance and testing of structures, systems and components which are important to safety.

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