For roughly three weeks every 18 months, a carefully orchestrated series of critical projects are carried out at Luminant's Comanche Peak Nuclear Power Plant with the most impeccable exactitude.
"We say perfection is the minimum standard,” shares Jeff Hull, refueling work window manager.
Welcome to a refueling outage. During this scheduled outage, the main activity is loading new fuel assemblies into the core. The core is the region of the reactor that contains the fuel and the nuclear reaction. In all, it holds nearly 200 assemblies, roughly half of which are replaced each outage.
"The fuel assemblies are taken out of the core and placed in the fuel building,” explains Hull. "When we're ready to complete the reassembly phase, we'll place the head back on the reactor vessel, bolt everything up and be ready to start the plant back up.”
While refueling may be the primary purpose of the outage, it's far from the only one. "We also take the opportunity to do preventive maintenance activities on pieces of equipment that we can't work on while the unit's running,” says Steve Smith, plant manager.
These activities run the gamut from internal inspections on the diesel generators, which are the plant's main emergency power supply, to the main generator and many things in between. No matter the project, they're all made possible by an intricate planning process that involves as many as 100 employees beginning preparations as far as 18 months out. It then takes an additional 1,000 contractors and a round-the-clock staffed control center to ensure safe and precise execution.
"We all know our key to success is how well we prepare,” says Smith.
And how safely they perform. With hundreds of equipment surveillance tests and 2,000 safety observations completed this outage alone, safety is unquestionably the plant's No. 1 priority.
"It really is a core value,” says Steve Nowak, Comanche Peak safety manager.
A core value tied to a standard of operational excellence, which means it's a job that's always top of mind, never finished – not even when the outage is.
"The true success of an outage is how well we run that 18 months when we're done,” says Smith.
Adds Dave Weyandt, diesel generator system engineer, "The bar is always being raised.”