16 September 2016

Unit 2 of the UK's Heysham II nuclear power plant was taken offline today for a scheduled maintenance and inspection outage, setting a new world record for the uninterrupted operation of a commercial power reactor. The achievement was announced by Vincent de Rivaz, CEO of EDF Energy, at the World Nuclear Association's Annual Symposium in London.

The Advanced Gas-cooled Reactor (AGR) - also referred to as Heysham 2 unit 8 - operated non-stop since 18 February 2014. The Heysham I and II plants feature a total of four AGR units.

The Heysham unit was taken offline after 940 days of operation (Image: EDF Energy)

De Rivaz said unit 2 of Heysham II had generated more than 14 TWh of electricity and avoided the emission of over 7 million tonnes of carbon dioxide over the 940-day run.

"It is just one example of the outstanding performance of EDF Energy's 15 nuclear reactors in the UK. Since the acquisition of the UK fleet in 2009, we have increased safety performsnce by 51%. We have increased our output by 50% and it's a personal best we will try to beat in 2016. And we have safely extended the life of our AGRs by 25%, eight years on average."

Earlier this year EDF Energy announced new extended scheduled closure dates for four of its nuclear power stations, with Heysham 2 now scheduled to operate until 2030, an extension of seven years.

AGRs - which are cooled with carbon dioxide, graphite-moderated and fuelled with enriched uranium - are designed to be refuelled without being shut down first. During the current run, 123 fuel channels have so far been refuelled.

The previous record for continuous operation was held by unit 7 of the Pickering plant in Ontario, Canada, which had an 894-day continuous run between 26 April 1992 and 7 October 1994. This is a Candu pressurized heavy water reactor (PHWR), also designed to be refuelled during operation.

Torness 2 in Scotland - also an AGR - ran for 825 days between 4 August 1997 and 7 November 1999, now making it the third longest running reactor.

Unit 5 at India's Rajasthan Atomic Power Project, a PHWR, achieved continuous operation of 765 days on 6 September 2014.

The current operating run of Torness 1, another AGR operated by EDF Energy, currently exceeds 740 days, but the unit is not scheduled to be taken offline for maintenance until next April.

The world record for continuous operation of light water reactors, which need to be shut down for refuelling, resides with Exelon's LaSalle 2 boiling water reactor. In February 2007 this unit was shut down after a run of 739 days, shortly after unit 1 at the plant completed a 711 days of uninterrupted generation. Calvert Cliffs 2 set a world record for continuous operation of a pressurized water reactor in February 2009, having operated without interruption for 693 days.