NUCLEAR emergency tablets should be distributed before one of two nuclear reactors at the Hunterston B power plant which were shut down last year returns to service, campaigners have said.

EDF Energy is expected to restart reactor four at its 40-year-old Hunterston B nuclear plant on the Firth of Clyde in North Ayrshire within weeks after the Office for Nuclear Regulation (ONR) said the plant was safe.

Hundreds of cracks were found in the graphite bricks within the reactor cores at the plant, taking the total over government safety limits. But now ONR has accepted that the operational allowance should be increased from 350 to 700 cracks leading to reactor four being cleared to return to service.

And Scottish CND which is concerned the move is "moving the goalposts" of safety has taken the opportunity to call for free potassium iodate tablets to be pre-distributed to the population within 30 miles of Hunterston.

READ MORE: Cracks at Hunterston B nuclear reactor breach safety limits

Potassium iodate tablets are used at the time of a nuclear emergency and stop the thyroid gland in your neck taking up radioactive iodine, which may be released into the environment following a nuclear accident.

HeraldScotland:

Lynn Jamieson, convener of Scottish CND's radiation risks working group said: "It would make sense to have them distributed before the reactor is restarted. It is prudent to have the thing that would help if there were accident, before any accident. "It is actually standard practice in some countries."

The regulator will allow reactor four to run for four months after proving that the cores can still fulfil their fundamental safety requirements, despite the cracks in its graphite bricks.

The regulator said its longer-term condition was "uncertain" and that EDF would need to justify its safe operation beyond this period.

READ MORE: Footage reveals cracks in nuclear reactor in North Ayrshire

EDF Energy closed reactor three of Hunterston B in March this year for more detailed investigation after more than 350 cracks were found within the graphite core - breaching the operational limit for the plant.

Reactor four was closed later in the year. Fewer cracks had been found, but experts predicted that it would soon also exceed the safety limit.

But Scottish CND has criticised the move to allow the reaction to come back into service by "moving the goalposts" of safety.

Arthur West, Scottish CND chairman said: “This news about the Hunterston reactor is very disappointing. It is very worrying that the ONR seems to have increased the number of cracks permitted in the reactor.

HeraldScotland:

"This move seems to be a clear case of moving the goalposts to allow the closed reactor to reopen. It really is time to think about a future beyond nuclear energy. The best response to the current situation at Hunterston is to continue the development of safer and cleaner forms of renewable energy."

Scottish CND’s nuclear risk special advisor Pete Roach added: “EDF Energy and ONR are gambling with public safety by allowing this reactor to re-open. Scotland doesn’t need the electricity – it is a risk not worth taking. This decision seems to be more to do with EDF’s financial problems than what is best for the Scottish public.”

Scottish CND said it thinks that both Hunterston B reactors should remain closed for good and that EDF and North Ayrshire Council should publish their plans for evacuation in the event of a nuclear accident.

Donald Urquhart, the ONR deputy chief inspector, said the regulator had made the decision to give Hunterston B’s reactor four the green light after a “long and detailed assessment of the safety case” submitted by EDF Energy.

He said: “Nuclear safety remains our utmost priority and we would only allow a reactor to restart with clear evidence that it remains safe for workers and the public.”

EDF, the French-owned energy company which owns and operates all of the UK’s existing nuclear power plants, said it had spent more than £125m completing the “most extensive investigation of the reactor core that has ever been undertaken” to prove the Hunterston plant’s safety.

The ONR's project assessment report said it had long been known that irradiation would lead to shrinkage and cracking of the fuel channel graphite bricks within reactors.

This was first observed at Hunterston in August 2014, when it was found in a small number of bricks in reactor four which were known to be more susceptible to cracking.

It was then discovered in the "main population" of graphite bricks in reactor three in October 2015, and in reactor four in September 2017.

Inspections carried out in March 2018 found that there were more than 350 cracked bricks in reactor three - above the operational safety limit. This limit had been set "well below" the upper safety limit of 700 cracked bricks.

An EDF spokesman said: “As a responsible operator we work with local and national agencies to prepare emergency arrangements in accordance with UK legislation and international safety guidance, none of which supports the need for the pre-distribution of stable iodine to a distance of 50km from nuclear sites.

“ In the UK there are areas which have been identified for specific arrangements in the unlikely event of an emergency. These Detailed Emergency Planning Zones (DEPZ) are areas immediately around each power station and as a further precaution there are also arrangements to extend public protection measures should the need arise.”