Nuclear regulator give permission to restart Reactor 4 at Ayrshire power plant
Reactor 4 at the Hunterston B power plant in Largs, North Ayrshire, has been given permission to be switched back on.
Lots of cracks were found in the graphite bricks, within the reactor cores.
Operator EDF say the reactor has been subject to extensive scrutiny and testing by their own internal Independent Nuclear Assurance, the Nuclear Safety Committee.
In a news release issued, operator EDF said:
"Since the decision was made to take both reactors off line last year, we have completed the most extensive investigation of the reactor core that has ever been undertaken. This has provided us with valuable knowledge about 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 other 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 defuelling and decommissioning.
"The safety case for the return to service of Reactor 3 at Hunterston B has been submitted to the ONR for their consideration."