20 Aug 19
Hunterston B - Graphite

Community update

20 August 2019

Dear SSG Member,

I am writing to inform you that the independent nuclear safety regulator, ONR, has given us permission to re-start Reactor 4 at Hunterston B power station, and we are now beginning a programme of work to bring the unit back up to power.  

This is the culmination of many months of hard work by the team here at Hunterston with support from many experts from across our organisation.

We presented a safety case for Reactor 4 that has been subject to extensive scrutiny and testing: by our own internal Independent Nuclear Assurance team, the Nuclear Safety Committee - a body of independent industry experts - and by the ONR themselves.

As you will know from our conversations at our meetings over the last 12 months, since we took the decision to take our reactors off line we have completed the most extensive investigation of the reactor core that has ever been undertaken.  This has provided us with valuable knowledge about the condition of the graphite core.  As part of this programme we have worked with the University of Bristol to confirm our understanding of how the core would react in the event of a major earthquake, of a magnitude never experienced in the UK.

Along with Bristol University, we have been working with leading consultancies and expert academics at universities across the UK including Strathclyde, Glasgow, Manchester, Oxford, Sussex, Nottingham and Durham as well as with leading UK companies such as Fraser-Nash, Wood and SNC-Lavalin.   We have also invested over 1000 person years into this research and invested over £125m in the programme.

As a result we have demonstrated that even in the most extreme conditions our reactors operate within large safety margins. In particular, all control rods would operate as they are designed to do and will safely shutdown the reactor in all circumstances. This has been agreed with the nuclear regulator, ONR, a statutory independent body which is representative of an industry whose regulatory regime is one of the most stringent and respected in the world.

It is important that we continue to monitor the core and so will perform frequent graphite inspections.  These will enable us to continue to demonstrate that the reactor operates with large margins to ensure safe operation at all times.  We will continue to demonstrate this safety-first  approach throughout the operating lives of our nuclear fleet, up to and beyond the point when we decide to end the generation phase and begin defueling and decommissioning.

We are going through a similar process for Reactor 3 at Hunterston B and have submitted a safety case to the ONR for their consideration.  I will continue to keep you updated on our progress in the usual way.

As always, please do not hesitate to contact me if you have any questions and I look forward to updating you further at our next meeting.

Colin Weir

Station Director Hunterston B