British reactor takes record for longest continuous operation

Unit 2 of the Heysham II nuclear power plant on the north west coast of England yesterday broke the world record for the continuous operation of a commercial nuclear power reactor. The reactor is due to be taken offline next month for maintenance.

Unit 2 of the Heysham II nuclear power plant on the north west coast of England yesterday broke the world record for the continuous operation of a commercial nuclear power reactor. The reactor is due to be taken offline next month for maintenance.

The Heysham II plant (Image: EDF Energy)

As of 1 August, the Advanced Gas-cooled Reactor (AGR) achieved 895 days of continuous operation, having operated non-stop since 18 February 2014. The reactor - also referred to as Heysham 2 unit 8 - is scheduled to continue operating until 16 September, when it will be taken offline for a planned maintenance and inspection outage. Assuming the unit carries on operating until that time, it would have run continuously for 941 days.

The reactor, operated by EDF Energy, has generated 13.495 TWh of electricity so far during this continuous operation, taking its lifetime generation to 115.46 TWh.

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.

In a letter to plant staff, station director John Munro said the performance of the Heysham II 2 reactor "represents world class, safe and reliable nuclear plant operation, achieving 0.3% UCFL [unplanned capability loss factor] for the period". He added, "We are absolutely right to feel very proud of this excellent performance."

The previous record 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, 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.

Researched and written
by World Nuclear News