EDF Admits Hunterston B’s Reactors are Cracking Up -But the Regulators Say : Its All OK Folks!

Photo by David Autumns
Hunterston B by David Autumns

From: <Contact@onr.gov.uk>
Date: Wed, Sep 16, 2020 at 3:25 PM
Subject: RE: HPGE202008123 Hunterston B

Dear Mr Autumns

Thank you for your email.

We recognise the decision to permission the restart of Hunterston B Reactor 3 will not be universally welcomed.

However, I would like to assure you that our specialist inspectors have spent the past two and a half years thoroughly examining the safety case for this next period of operation.  We must, therefore, disagree with your assertion that ONR has “waved through the restart”.  This is most certainly not the case – we have required EDF Energy NGL (EDF) to provide substantial evidence to demonstrate the safety of the reactor in a number of key areas. After a detailed and rigorous assessment exercise, which took into account ageing and degradation, our team of specialist inspectors concluded that a safety case that met our regulatory expectations had been provided by EDF.

As I’m sure you will be aware, graphite cracking is a well-known phenomenon in Advance Gas-cooled reactors and is expected as the reactors age. Our assessment of the safety case submitted by EDF to request permission to return Reactor 3 to service focused on ensuring that the cracking observed in the graphite core of the reactor would not compromise its fundamental nuclear safety requirements.

We are satisfied that EDF has demonstrated to us that the level of cracking observed and predicted to occur during this next period of operation will not compromise the ability of the core to fulfil its fundamental safety requirements, and that substantial margins of safety will remain in place. 

The safety of workers at the site, local residents and the wider public is our priority and we would not allow any nuclear facility to operate if it wasn’t safe to do so.

Further information about our decision to permission the restart of Reactor 3 can be found in the Project Assessment Reports (PARs), available on our website

Kind regards

Jessica McGuinness

Policy and Communications Directorate



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