Steve's Soapbox

Thursday, October 13, 2005

Commanche Peak: How would this be handled in Texas ?

Problem with reactor cooling system went undetected for years

By BOB CHRISTIE
Associated Press Writer
PHOENIX — A potential problem with the emergency reactor core cooling system at the nation's largest nuclear power plant went undetected since it began producing power in 1986, the Nuclear Regulatory Commission and the plant operator confirmed Thursday.
The issue was identified when engineers at the Palo Verde Nuclear Generating Station did an analysis after NRC inspectors raised questions at a detailed inspection early last week. The NRC was following up to see if earlier cooling system problems had been fixed.
The plant provides electricity for as many as 4 million customers in California, Arizona, Texas and New Mexico served by seven utility companies.
The review showed the emergency cooling system may not operate as expected to provide water to reactor cores after a small leak in the reactor cooling lines, NRC spokesman Victor Dricks said.
The worst-case scenario of an emergency cooling system failure is a meltdown of the reactor core and release of radioactivity into the atmosphere. Plants have so many redundant systems, however, that many other failures would have to occur before that happened, nuclear experts said.
The design flaw put the plant outside of it licensing guidelines and operator Arizona Public Service shut down the two operating reactors immediately until a fix is put in place. The third reactor in the complex 50 miles west of Phoenix was already down for maintenance and refueling.
There's no estimate for when the plant will come back online.
Engineers are looking at reconfiguring the system or writing new manual procedures to get around the problem, plant spokesman Jim McDonald said. They also are rechecking their calculations to see if the system may actually operate as expected.
The power is cheaper than many other sources, but several power companies say it is unclear if they'll need to raise rates to recoup their losses.
The emergency cooling systems in each of the three units are designed to replace water cooling the reactor cores in unusual situations.
Earlier this year, the NRC fined the plant operator $50,000 because of another problem in a different part of the same cooling system.
In the more recent case, pumps that provide emergency cooling water may not sense that a storage tank is getting low on water and switch to another source, Dricks said.
The fact the potential problem took so long to be discovered should prompt the NRC to look at other plants and procedures, said David Lochbaum, a nuclear safety engineer for the Union of Concerned Scientists, a nuclear watchdog group.
Lochbaum said the Palo Verde plant has been a "stellar" performer until the past two years, when a series of problems have cropped up.
"It's a fairly subtle problem, and it was a good catch by the NRC," Lochbaum said of the current issue. "It just would have been a great catch sooner."
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On the Net:
APS: http://www.aps.com
source: http://www.statesman.com/metrostate/content/gen/ap/AZ_Palo_Verde.html




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October 13, 2005 - 7:07 p.m. CDT