'Mushroom cloud' over EDF Heysham 2 nuclear power station after residents report 'loud bang'

Pictures showed a giant plume of steam in a mushroom shape above the Heysham 2 plant at around 5pm on Wednesday.

It followed a ‘loud bang’ at the power station, with alarmed residents calling fire crews to the scene to investigate.

EDF, the plant’s operators, said the alarming-looking cloud and loud noise was caused by an ‘unexpected’ incident with a nuclear reactor - but explained it was "no cause for concern".

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What happened?

EDF said the cloud was comprised of "clean steam" and was caused by a reactor unit "coming offline" unexpectedly.

A spokesperson for EDF said: "On Wednesday, one of the units at Heysham 2 power station came offline.

"This was not planned and noise caused by steam venting may have been heard by local residents.

“This steam venting is normal when a reactor comes offline and is no reason for concern.

“Work is under way to establish the cause of the trip and bring the unit back online.”

The fire service confirmed it was called to the site by residents, but said its services were not required.

Heysham 2 also went offline over Christmas due to an issue with the high voltage transmission system run by National Grid.

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Incidents at Heysham plants

Loud bangs from Heysham 2 also startled residents in 2019 when an electrical fault disrupted its control system, leading to a complete shut down of one of its nuclear reactors.

The 2019 shutdown meant Heysham 2's reactor 8 ceased its world record-breaking run for the longest continuous operation of a nuclear generator without a shutdown.

In 2018, three EDF employees were seriously injured in a steam leak at Heysham 1, prompting an investigation by the government's nuclear watchdog into safety standards at the site. Two of the casualties were taken to Royal Preston Hospital, Lancashire's major trauma unit, and a third person was taken to Wythenshawe Hospital’s specialist burns unit in Manchester.

In 2015, Heysham 1 suffered a major incident when it suffered a significant CO2 leak. A failed pipe at the facility released approximately 30 tonnes of clean Carbon Dioxide (CO2) into the atmosphere.

There was no immediate nuclear safety or radiological risk as a result of the event, but the government's nuclear watchdog, the Office for Nuclear Regulation (ONR), warned that the incident "could have had serious implications if workers had been in the vicinity, including potential fatalities".

Future of Heysham 1 & 2

The Lancashire site is the only one in the UK to have two operating nuclear power stations.

Heysham 1 began operating in 1983 and has two advanced gas cooled reactors, scheduled for closure in 2027.

The second plant started generating in 1988 and its two gas cooled reactors are due to close in 2030.