A reactor at the Hunterston B nuclear power station in Scotland will remain offline for safety checks after fresh cracks were found.

Operator EDF Energy said an inspection of the graphite bricks that make up the reactor 3’s core confirmed new “keyway root cracks”, developing at a “slightly higher rate than anticipated”.

It added it will be working with the Office for Nuclear Regulation (ONR) to ensure the long term safety case reflects the findings of the inspection.

Last year, Hunterston B produced enough electricity for 1.8 million homes, avoiding 2.5 million tonnes of emissions – equivalent to taking 1.1 million cars off the road for a year.

EDF will require ONR’s permission to restart the reactor, which the energy firm expects to happen before the end of the year.

That will result in a reduction in 2018 nuclear output forecast of up to 3TWh.