The Palo Verde Generating Station is the largest nuclear reactor in the country.
Located 50 miles west of Phoenix, it employs 2,500 people and supplies one-third of all power used in Arizona.
ABC15's Melissa Blasius was granted an exclusive look inside the plant to see how it refuels and maintains its reactors, and sat down with the site's top nuclear officer to ask what's been done to change the site's history of safety violations.
The generating station had one of its three reactors offline, allowing our cameras to go inside the radiation containment area.
At the bottom of the pool, a robot uses ultrasound to check for weak spots. Work now can help prevent emergency shutdowns for repairs later.
Last December, a backup generator at the plant failed --exactly the component expected to prevent a nuclear meltdown in an emergency. Since then, officials said they have taken steps to reexamine the other emergency generators.
"We determined the cause of that failure [and] repaired it," said Tim Gavigan, head of training at the site. "We inspected our other emergency generators for those same sorts of indications and we found none."
Four years ago, federal regulators found Palo Verde had the second-highest number of safety violations at any nuclear facility in the country.
After that, Chief Nuclear Officer Bob Bement said the station sought outside help to review their entire operation.