Everything about Diablo Canyon Power Plant seems big to a visitor stepping from a bus Monday morning for a tour of the facility.

From the massive twin reactor containment domes and a generator building big enough to park a blimp inside to the 12,500 acres of nearly pristine property that surrounds it, the plant is impressive.

Even its grand view of the Pecho Coast and the Pacific waves crashing on PG&E’s 14 miles of rugged shoreline is awe-inspiring.

It’s a sight rarely seen by the general public, usually viewed only by Pacific Gas and Electric Co. employees, contract workers and federal regulators.

But Pacific Gas and Electric Co. organized Monday’s tour to give a handful of journalists an inside look at upgrades and routine maintenance under way while the Unit 2 reactor is shut down for refueling.

About 35 days into a 52-day “outage,” work to replace an analog control system with a new state-of-the-art digital system is progressing smoothly, plant officials said.

Replacement of the “polar crane,” which moves the huge components inside the containment dome, is also nearing completion.

“We’ve still got two weeks to go,” said Edward Halpin, senior vice president and chief nuclear officer at the plant. “We’ve been at it for five weeks, and it’s gone well for us.”

“Big” also applies to the work that’s being done, which goes far beyond those two projects, and the small army of expert workers who are swarming around and through the plant.

Some 11,000 operations are being performed by 1,000 people brought in to supplement the plant’s regular workforce of 1,483 employees.

In all, crews will put in 300,000 to 400,000 man-hours of work during the refueling and maintenance.

By the time the outage is complete, workers will have removed the unit’s 193 fuel assemblies, replaced one-third of them, then returned them to the reactor.

Routine maintenance includes such things as retightening the stator windings — the outer coils of wire — in the generator, said Jim Welsch, station director.

Halpin noted Unit 2’s entire acid-caustic system is being replaced.

At the same time, other workers are taking apart components that can’t be examined when the plant is in operation and “looking for problems,” Welsch said.

In the Unit 2 control room, operators are checking switches, breakers and gauges for proper operation.

In the meantime, the daily routine goes on for many PG&E employees, as Unit 1 continues operating at 100-percent power.

Its generator, driven by 800 to 1,000 pounds of pressurized steam, is spinning at 1,800 rpm and cranking out 1,150 megawatts of electricity — enough to supply 1.5 million customers with power.

When both reactors are at full power, the plant generates 2,300 megawatts. If the plant was burning coal to generate that energy, the amount of fuel that would be needed is astounding.

“You’d see 600 (railroad cars of coal) coming down Cuesta Grade every day,” said John Lindsey, plant meteorologist and tour guide.

Welsch said the budget for the refueling and maintenance outage is $50 million, which works out to about $1 million a day.

But Halpin noted that represents an investment in the safe, reliable operation of the plant that gives the local economy a huge boost.

With a payroll of $202 million a year, PG&E also pays $25 million in property taxes and spends $22 million annually with local vendors, Halpin said.

He noted that a study prepared for Pismo Beach indicated each refueling outage has a $5 million impact on the city, as the influx of temporary workers fills hotel rooms and patronizes restaurants and shops.

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