693 days of continuous operation

23 February 2009

A new world record for continuous operation of a pressurized water reactor (PWR) has been set. Calvert Cliffs 2 operated without interruption for 693 days.


The milestone was announced by plant owner Constellation today as the unit was taken offline for refuelling. Brew Barron, the company's executive vice-president described the achievement at "phenomenal", while site vice president Jim Spina said it would not have been possible without "employees' unwavering commitment to safety, human performance and equipment reliability."


Calvert Cliffs Turbine Hall (Constellation)
Doing the business: Inside the turbine hall at Calvert Cliffs
(Image: Constellation)


Calvert Cliffs 2 generated some 32 billion kWh during its 693-day run, which works out as a 99.3% capacity factor according to Constellation. The previous record holder was Exelon's Three Mile Island 1 with a run of 689 days.


World Nuclear News understand the world record for continuous operation of any light water reactor resides with Exelon's boiling water unit LaSalle 2. In February 2007 that reactor shut down after a run of 739 days, shortly after its sister unit number 1 completed a 711-day uninterrupted generation run.


US nuclear power reactors achieved an average capacity factor of 91.8% in 2007, up from 66% in 1990 and 56.3% in 1980.


The longest operating period for any power reactor belongs to Ontario Power Generation's Pickering 7, which was shut down on 7 October 1994 after operating continuously for 894 days. That reactor is a Candu pressurized heavy-water unit, which can be refuelled while online.