March 8, 2019– Mary Greeley News – The cracks are well within safety limits and the reactor would still be able to shut down in an emergency, says EDF.
Footage has been released showing some of the hundreds of tiny cracks inside a nuclear reactor in North Ayrshire.
Reactor 3 at the Hunterston B plant has been shut down for 12 months after the cracks were found to be growing faster than expected.
NUCLEAR experts have warned of a Chernobyl-like "catastrophic accident" after more than 350 cracks were discovered in the power reactor at the Hunterston plant in North Ayrshire https://t.co/NiElpfMLLD
— Peter Roche (@PeterRoche3) November 22, 2018
Cracks are expected to form over time in all the UK’s nuclear reactors, but recent close-up filming at Hunterston has revealed around 370 small fractures.
EDF, which runs the plant 35 miles west of Glasgow, said they were 1mm when first seen in 2017.
They are now “opening very slowly”, with an average crack size of 2mm.
Cracks of 10mm on the inside of the fuel channel and 18mm on the outside are still safe, according to EDF.
The company says it has carried out tests, including earthquake simulations, which show the reactor will still work normally and allow control rods to shut down the reactor in case of an emergency.
“We’ve carried out one of our biggest ever inspection campaigns on reactor three, we’ve renewed our modelling, we’ve done experiments and tests and we’ve analyzed all the data from this to produce our safety case that we will submit to the ONR.
“We have to demonstrate that the reactor will always shut down and that it will shut down in an extreme seismic event.”
The operational limit for the latest period of operation was 350 cracks but an inspection found that allowance had been exceeded.
Electricity output from the Hunterston B nuclear power station could fall by 40% this year after dozens of cracks were discovered in one of the reactors https://t.co/i0UIf5jjhI North Ayrshire #EDF #UK #energy #tech #security Fail #community #health #humanrights #policy
— Cecalli Helper (@Cecalli_Helper) May 3, 2018
EDF plans to ask the regulator for permission to restart with a new operational limit of up to 700 cracks.
The cracks cannot be repaired because it is too dangerous and soon the reactor – like others around Britain – will have to be decommissioned.
The company is planning to ask permission from the nuclear watchdog, the Office of Nuclear Regulation, to restart the reactor.
The 10m-high, 1,400-tonne reactor is made up of 3,000 graphite bricks and the plant provides electricity for 1.8 million homes when all the reactors are running.
Operators EDF Energy say the cracks pose no threat to safety at the site.
But paperwork obtained through a freedom of information request shows the Office for Nuclear Regulation have raised concerns over fractures in the brick keyways that lock together the core in reactor three.
It’s feared the same problem could arise at EDF’s sister station – Hinkley B in Somerset.
The ONR have agreed the stations can continue operating safely after making changes to the reactor shutdown process of the 70s structures.
But John Large, who helped design the advanced gas-cooled reactors, believes that if the cracks get worse, they could jeopardize a reactor’s stability in the event of a disaster and make it impossible to shut it down.
He said: “These keyways are beginning to fracture… that means the locking together, the way that force can be transferred from one brick to another, is lost, so it becomes a very loose stack of bricks.”
Allan Jeffery of campaign group Stop Hinkley said: “If you can’t get the control rod down, you can’t control the temperature inside the reactor and you’re heading for accidents – possibly even meltdowns.”
But EDF director of nuclear operations Brian Cowell said: “We know that having a small number of cracked bricks in this massive structure (of the core) is completely irrelevant to the safety function.”
credit: In part with https://www.bbc.com/news/uk-scotland-47485321