Unit 1 reactor of the Palo Verde nuclear plant is running almost at full power, just in time to help Arizona utilities meet record demand for electricity.
The unit had been shut off or running at reduced power since fall because of a vibrating emergency cooling line. Arizona Public Service, which operates the plant, fixed the problem by installing a massive new valve the size of a small pickup truck, and that work concluded July 7.
At that time, the unit was running at 80 percent of its 1,300-megawatt capacity, and since then the utility has ramped up the power to 90 percent, said APS spokesman Jim McDonald. The unit should be operating at full capacity within a few more days, although McDonald said there is no set schedule.
The other two reactor units at the plant, located about 50 miles west of Phoenix, are running at 100 percent of their capacity, he said.
The long curtailment of Unit 1 has resulted in an economic loss to APS of about $46 million because of the higher cost of obtaining replacement power.
McDonald said the company will ask the Arizona Corporation Commission for permission to recover that amount from customers via higher rates.
The ramp up of Unit 1 comes as APS and Salt River Project, which also obtains power from Palo Verde, are reporting record demand for electricity due to high temperatures and population growth in the Valley.
On Thursday, SRP set a record for peak demand at 6,342 megawatts while APS set a record of 7,340 megawatts.
That eclipsed the previous records on Wednesday of 6,141 on the SRP system and 7,103 for APS.
For comparison, 100 megawatts is enough to serve about 25,000 average-sized homes.
APS spokesman Alan Bunnell said temperatures around the Valley were a few degrees higher Thursday than on Wednesday, which accounted for the increase as customers cranked up air conditioners to keep cool.
The peaks reached on Thursday where higher than the predicted peaks for the summer by both utilities.
SRP had predicted a summer peak this year of 6,210 megawatts while APS had projected a peak of 7,322 on its system.
But SRP spokesman Jeff Lane said Valley utilities have sufficient reserves to cover the higher demand.
“As long as all the power plants are working properly and wildfires don’t take down transmission lines into the Valley, we should be fine,” he said.
Bunnell said demand may decline slightly today because energy use typically drops on Fridays as people leave work early.