Romney Marsh's nuclear power station's operator has been served with enforcement action following a 'significant lapse' in safety.

EDF, which runs the plant, was served the formal ‘direction’ by the Office for Nuclear Regulation (ONR) and was told that improvements are needed on site following the incident in May this year.

The energy firm says operational procedures have now been 'tightened' as a result.

The incident in question saw chemical damage occur within some of the tubes in the station's boilers.

As the boilers are located within the reactor area, they cannot be accessed for repairs or detailed investigations.

As such, the damage done, which is estimated to have reduced the thickness of some of the tubes, can only be calculated.

But it is believed that during testing and warming up of the reactors, staff at Dungeness allowed higher than specified levels of oxygenated water into the boilers.

This failure "caused minor damage" within the boiler tubes.

This was later highlighted by technical colleagues who identified the station had not followed the latest boiler chemistry advice, specifically created to minimise the risk of boiler tube damage.

EDF then reported the damage to the ONR and worked with them throughout their investigation.

But the firm confirms that is was never a nuclear issue, and says despite the incident, the boilers fortunately remain safe to operate.

The boilers will need to remain in operation for several years as Dungeness completes the defueling process, which was announced earlier this year.

'This significant lapse should never have happened - we take the safety of our plant and people extremely seriously...'

The station is being decommissioned seven years earlier than expected due to ongoing technical challenges at the plant, which has been offline since 2018.

An EDF spokesman said: "While testing components in Dungeness B’s reactors, chemical damage was done to some of the tubes in the station’s boilers.

"This was later highlighted by technical colleagues who identified the station had not followed the latest boiler chemistry advice, specifically created to minimise the risk of boiler tube damage.

"This significant lapse should never have happened - we take the safety of our plant and people extremely seriously.

"The station has since tightened operational procedures, improved oversight of key chemistry decisions and created a specific training programme for relevant staff.

"EDF notified ONR of the damage to the tubes as soon as we were aware of it and has worked with inspectors on their investigation.”

A spokesperson for ONR said: "We are satisfied that this event posed no nuclear safety risk to workers or the public, but we require the necessary improvements to be identified and made in line with the high safety standards expected at nuclear facilities."

The direction from ONR requires EDF to review and reassess its arrangements for controlling feedwater quality at the plant.

The company must demonstrate a detailed schedule of improvement plans and actions to ONR by December 1, 2021.

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