Hunterston B 'cracks' not a cause for concern

Cracks found in two of the 6000 graphite bricks in unit 4 of the Hunterston B nuclear power plant in North Ayrshire, Scotland have no safety implications, Colin Weir, station director at the plant said today in response to media coverage of the matter.

Hunterston B power station is a nuclear licensed site operating two Advanced Gas-cooled Reactors - units 3 and 4. To continue to operate safely and reliably the reactor plant requires examination, inspection maintenance and testing. Continuous improvement also requires plant upgrades to be implemented where deemed to be reasonably practicable. Whilst some of these activities can take place when the reactor is at power, many of them require it to be shutdown.

"Every time we take the reactor out of service for planned maintenance we inspect the graphite core which is made up of around 6000 bricks. During the current Hunterston outage we found two bricks with a new crack which is what we predicted during Hunterston B's lifetime as a result of extensive research and modelling," he said.

"It will not affect the operation of this reactor and we also expect that a few additional cracks will occur during the next period of operation. The small number of cracked bricks found during routine inspection is in line with our expectations, the findings have no safety implications and are well within any limits for safe operation agreed with our regulator."

The Office for Nuclear Regulation (ONR) said on 1 October it had given EDF Energy Nuclear Generation Limited, the licensee of Hunterston B nuclear power plant, consent to start up unit 4, which has been in periodic shutdown since 1 August.

"The licensee's arrangements require that periodic shutdowns are carried out every three years at each reactor at Hunterston B, providing the opportunity to undertake such activities," ONR said. "On completion of a periodic shutdown the reactor concerned cannot be started up without consent from ONR. ONR specialists have completed their inspections of the work carried out are satisfied that the licensees justification to start-up the reactor and operate for a further period of three years is adequate," it said.

Researched and written
by World Nuclear News