THE Royal Navy is to make changes to its procedures, equipment and the way it informs the public after it admitted an 'unauthorised discharge' of radioactive liquid into the River Tamar, writes William Telford.

An investigation into last month's leak of coolant, from a hose linked to the submarine HMS Trafalgar, is close to completion.

But top brass released details of the incident and interim findings at yesterday's Devonport Local Liaison Committee Meeting, which discusses naval base safety.

They stressed that the harm caused by the leak of about 280 litres of coolant containing radioactive cobalt-60 and tritium was 'insignificant'. But, nevertheless, they said the Senior Service should not be 'complacent'.

And, following criticism of the time it took to inform the public and Plymouth City Council, Commodore Ian Jess, Devonport's Naval Base Commander, told the meeting: "It was an unauthorised discharge and our notification procedures were not as they should be, which added to people's worries over the event."

He said reviews were being carried out into both the incident and the 'communication' and said changes would be made 'to reduce the risk of it happening again'.

Head of base safety Captain John Taylor explained that the leak happened overnight on November 6 and 7 when the 'primary coolant' was being pumped off HMS Trafalgar at the naval base's seven wharf.

He said a hose connecting the vessel to a 'primary effluent tank' on the dockside 'failed' and showed the meeting, attended by about 30 people, a photo of the damaged pipe.

Since the incident seven wharf has not been used for this practice, and it was also stopped on eight and nine wharves temporarily.

But these wharves do not suffer from the same tidal range, and submarines can get closer to the jetty, so hoses are less susceptible to damage, Capt Taylor said.

He said that only 'the youngest hoses' were now being used but also said there may have to be 'physical change' to seven wharf so it can be in operation again.

The Environment Agency's Dr Paul Naylor told the meeting that the coolant contained 0.001 per cent of the dockyard's annual authorised level of cobalt-60 and 0.1 per cent of tritium.

But the incident was still 'a serious unauthorised release'.

The EA analysis was carried out about 14 hours after the spill. City Councillor George Wheeler asked Dr Naylor about issues raised in a letter from environmental science lecturer Dr Colin Trier, of the University of Plymouth, particularly about swimmers who used the Sound shortly after the leak.

Dr Naylor said that as soon as the EA knew about the amount of radioactive material released it was 'satisfied there was no risk to the public'.

Following the leak the MoD was criticised, by Plymouth City Council among others, for not informing the public until the media broke the story.

Cdr Jess said that had the leak been significant the public would have been notified immediately, but said the MoD was looking at when the public should be told of less serious events.