WINTERSBURG - Security officials at the nation's largest nuclear power plant detained a contract worker with a small pipe bomb in the back of his pickup truck Friday, authorities said.
The Department of Homeland Security said there was no known terrorism link to the incident at Palo Verde Nuclear Generating Station west of Phoenix.
The worker, Roger William Hurd, told investigators he didn't know how the bomb got in his truck and was released Friday afternoon.
Palo Verde officials said they pulled Hurd's security clearances and won't allow him back until they know more about what happened.
"He won't just drive up to work again like nothing had happened," plant spokesman Jim McDonald said. "We're going to have to look at the investigation. We're not making any assumptions."
Hurd, 61, was stopped and detained at the entrance of the nuclear generating plant, about a half mile from the containment domes where the plant's nuclear material is stored, McDonald said. Security officials then put the nuclear station on lockdown for a few hours, prohibiting anyone from entering or leaving the facility until Friday afternoon.
Authorities described the device as a six-inch capped explosive made of galvanized pipe that contained suspicious residue. Tom Mangan, a spokesman for the Bureau of Alcohol, Tobacco, Firearms and Explosives, said it was likely homemade.
"If this thing went off in the bed of the truck, it certainly would put a hole in it," Mangan said. "It was rather crude in construction, but it could certainly injure somebody."
Capt. Paul Chagolla with the Maricopa County Sheriff's Office said the pipe was not hidden. He said Hurd normally drove a motorcycle to work but was in a truck Friday because of the cool weather.
Sheriff's officials rendered the device safe.
Hurd later told investigators the bomb wasn't his, and he had no idea where it came from, Sheriff Joe Arpaio said.
"So, the mystery is how did that pipebomb get into his truck? Arpaio said. "What's the motive to someone to put this in his truck? I don't know. Was it a disgruntled employee? I don't know. Were they trying to target him?"
Arpaio said investigators searched Hurd's home but found nothing to helpful. Hurd wasn't arrested, and Arpaio said he expects Hurd to help with the investigation.
Nobody answered the door at Hurd's apartment in Goodyear, Ariz. Messages left by The Associated Press at numbers listed for Hurd in Arizona and Hartsville, S.C., weren't immediately returned.
Doug Walters, the senior director of security for the Nuclear Energy Institute, the industry's trade group, said Palo Verde's response was "exactly what you would expect it to be."
"We have a checkpoint for this reason," Walters said. "They were able to identify a suspicious item in the truck. I don't know what they could have done differently."
Hurd worked as a procurement engineer, responsible for evaluating equipment purchases for the plant, Palo Verde officials said.
He had access to protected areas but hadn't been in any such area since Aug. 21, said Randy Edington, the chief nuclear officer for plant operator Arizona Public Service Co.
Edington said Hurd would have had access to the reactors but officials didn't know the last time he would have been near the reactors.
The incident was considered an "unusual event" - the lowest of four emergencies the plant can declare, said Jim Melfi, an inspector with the U.S. Nuclear Regulatory Commission.
There was no threat to the public, McDonald said.
McDonald wouldn't say which company employed Hurd. Like everyone who has access to the plant, Hurd submitted to a background check.
Workers also must pass through two security checkpoints to get inside one of the plant's three containment domes, which house the radioactive nuclear material. One of the checkpoints includes an automated system that sniffs workers for the presence of bomb-making materials, McDonald said.
Palo Verde, operated by Arizona Public Service Co., is the nation's largest nuclear power plant both in size and capacity. Located in Wintersburg about 50 miles west of downtown Phoenix, the plant supplies electricity to about 4 million customers in Arizona, New Mexico, Texas and California.