Refueling Outages: Delivering Fresh Fuel and Electricity Reliability

John Keeley

Outage management at nuclear power plants over the years has evolved into a sophisticated and meticulously chronicled endeavor, carried out over the course of about 30 days. This month I am being afforded an insider's view of Palo Verde unit 2's outage, and the planning and coordination associated with more than 10,000 jobs being carried out this month within the unit is nothing short of staggering.

The work performed during refueling outages is a cornerstone for reliable operations throughout the following operating cycle. The Palo Verde Nuclear Generating Station is perhaps the best-practiced site in outage work across the U.S. nuclear fleet, and for an obvious reason: by virtue of having three units, with staggered outage schedules, they carry off two refueling outages each and every year. Outage management at Palo Verde, to this observer's eyes, is as close to an exact science as is possible in this industry.

Nuclear plants enter refueling outages in spring and fall, to refuel but also to carry out numerous maintenance tasks small, medium and enormous in scope to ensure reliable electricity for consumers when it's needed most -- in the heat of summer and chill of winter. It's worth noting that in the extreme heat of the Arizona desert leading up to this outage, from June 15 to September 15, all three Palo Verde units operated at 100 percent capacity. If you've ever summered in Arizona, you know why that level of reliability is so important.

The term "refueling outage" is a bit of a misnomer. The actual refueling takes between four and six days, but the bulk of outage work involves rigorous inspections and component maintenance. Significant outage work has to be performed while a reactor unit is offline, and it's during this time that workers will perform major maintenance and refurbishment on a unit's turbine, steam generators, pumps, motors, valves, and cooling towers. Systems and component inspections of extraordinary depth and detail also take place.

Occasionally outage inspections will uncover a component that needs to be replaced but isn't easily located or readily available. In past outages, under exceptional circumstances, site personnel have actually boarded airplanes, flown great distances to retrieve a coveted component, and actually purchased a seat for the part on the plane ride back to Phoenix in order to get it in place in time to meet the outage schedule. Overnighting parts sometimes isn't fast enough. In one outage instance, Palo Verde even had a bearing boxed up and boarded onto a privately chartered jet to get it on site in adherence with the outage work schedule. The cost of not returning the unit back into operations on time far exceeds even the cost of a chartered jet.

Palo Verde has a Central Command for every outage -- its Outage Control Center. Leaders from engineering, operations, maintenance, radiation protection, chemistry, worker safety, supply chain, and outage oversight among other work groups man and monitor information portals chronicling work flow virtually minute by minute, around the clock. There's a media cabinet housing 11 hard drives that feed high resolution visuals to a bank of television screens that run the entire length of one of the center's walls. Staffers at NASA's Mission Control would feel very much at home here.

I've attended multiple outage update meetings every day during the past two weeks, and the dominating dialogue within them involves worker safety and safe job execution. The success of 2R19 -- the designation for Palo Verde unit 2's autumn 2015 outage -- will be determined by its safety metrics.  

There are more than 800 augment outage workers in addition to normal staff now on site at Palo Verde, and the plant will spend upwards of a million dollars a day in maintenance and improvements for the duration of the outage. The site makes so sizable an investment in resources because its mission is so central to a quality way of life in the American Southwest. Palo Verde has become an industry leader in carrying out outages safely and efficiently, and the residents out here in the desert are able to stay cool because of it.

EDITOR'S NOTE: In the Summer of 2014, NEI published a content package on reliability and the nuclear energy industry. That package covered the value of always-on power and took a close look at just how plants like Palo Verde prepare for peak demand during the Summer and Winter months.