Heysham 1 power station has been given an improvement notice from the Office for Nuclear Regulation (ONR) after a leak from a pipe carrying clean carbon dioxide gas.
Around 30 tonnes of clean CO2 were released from a corroded pipe in the carbon dioxide storage and distribution plant at Heysham 1 on March 16.
There was no release of radioactive material, no persons were injured and the two nuclear reactors at Heysham 1 remained operational during the event.
A spokesman for Heysham power stations said there was never any threat to the public.
The ONR said power station owners EDF Energy had “compromised the safety of its employees” by failing to meet a condition of its nuclear site licence.
This condition calls for them to make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of its facilities.
The site is now planning to repair the affected pipe, part of the site’s back-up CO2 supply system.
Ian Stewart, station director at Heysham 1, said: “We have already taken action here on site to ensure that lessons are learned from this event.
“We will continue to work closely with our independent regulator, the ONR, to implement the highest standards of maintenance at Heysham 1.”
An investigation of all pipework associated with CO2 storage and distribution on site found no other similar issues.
CO2 is used as a coolant by power stations and is stored on site to maintain easily accessed back-up supplies of the gas.
The Office for Nuclear Regulation (ONR) independently regulates nuclear safety and security at 37 nuclear licensed sites in the UK.
An ONR improvement notice formally requires power station owners EDF Energy to make improvements related to a specific issue – in this case the maintenance and inspection of Heysham 1’s CO2 storage areas. They have to demonstrate the improvements by September 30.
There are currently planned maintenance outages (10-week shutdown and repair programmes) taking place at two of the four Heysham power stations reactors, one at Heysham 1 and one at Heysham 2. These shutdowns are unrelated to this incident.