[NukeNet] More trouble for Palo Verde Nuclear Power Plant

[The Roy Process]

http://www.azcentral.com/business/articles/1208biz-paloverde1208.html
More trouble for Palo Verde 
Already in hot water with nuclear agency, plant officials must explain generator ills

Mark Shaffer
The Arizona Republic
Dec. 8, 2006 12:00 AM 


Palo Verde Nuclear Generating Station could be in a deeper hole with the Nuclear Regulatory Commission after preliminary inspection findings that the plant had an inoperable emergency diesel generator for much of September. 

The commission and Palo Verde officials will meet Jan. 16 in Arlington, Texas, to discuss the agency's report on the then-faulty Unit 3 generator, which was released Thursday.

The stakes are expected to be high for the nation's largest nuclear power plant, 50 miles west of downtown Phoenix. 

If the NRC finds that the violation is anything more serious than that of low-safety, or "green," significance, Palo Verde will sink to the level of the most heavily monitored nuclear power plant in the country, along with Perry in Ohio. 

That likely would cost Arizona Public Service Co. and ratepayers millions of dollars because of repairs the increased scrutiny would mandate.

The nuclear plant also could end up at a higher level of regulation if the NRC finds anything more than a low-safety violation because of a bad chemical mix that plant workers placed in emergency spray cooling ponds from 1994 to earlier this year.

Excessive amounts of zinc and phosphate had been mixed into the water to try to control erosion of safety components in pipes. But the chemical mix led to deposits on the tubes, increased insulation and incorrect heat transfer.

A final report on the chemicals in the cooling ponds is expected before the end of the year, said Victor Dricks, an NRC spokesman.

"Each of the findings of these inspections will be assessed independently," Dricks said. "But one more finding of anything but green will change the landscape for Palo Verde."

Jim McDonald, a spokesman for APS, the largest stakeholder in Palo Verde, acknowledged that performance at the plant "hasn't been up to our high standards of the past, and we're committed to changing that."


'Degraded cornerstone' 
Palo Verde already is one of the most-monitored plants in the country by federal regulators. 

It is classified as a "degraded cornerstone" because of a "dry pipe" that was found during a 2004 inspection that had the potential to disrupt the flow of water to the core's emergency cooling system.

According to the NRC's report, a federal investigations team was sent to the plant in early October to look into failures in the emergency diesel generator on July 25 and Sept. 22 that interrupted electrical transfers.

Each of the three units at Palo Verde has two of the 5,500-kilowatt generators to provide standby power if the normal power supply is lost.

The NRC report noted that the generator was inoperable from Sept. 4 to Sept. 22 and that incorrect maintenance had been conducted on an electrical relay in the unit.

"The licensee (Palo Verde) determined the root cause . . . could be attributed to either plastic debris or oxide film buildup," the report said.

Reach the reporter at mark. shaffer at arizonarepublic.com. 
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