Re: PWR CRACKS!!! Just as I FIRST predicted so long ago!!! (followup)

----- Original Message -----

From: Russell D. Hoffman

To: tat

Sent: Sunday, October 14, 2001 2:42 PM

Subject: San Onofre to be checked for new kind of crack

San Onofre to be checked for new kind of crack

Phil Diehl

Staff Writer

SAN ONOFRE ­­ Federal regulators have instructed nuclear power plant operators, San Onofre among them, to examine their reactors for a newly discovered type of cracking that could release radioactive steam into the domed containment structures.

A Nuclear Regulatory Commission bulletin issued Aug. 3 asks nuclear power plant operators to look for circular cracks like those discovered recently for the first time in the heads of two reactors at the Oconee nuclear power plant in South Carolina, said Sue Gagner, a spokeswoman at the commission's headquarters in Rockville, Md.

San Onofre nuclear plant will be inspected for cracks that could lead to radioactive steam leaks.

"What made (the new cracking) unusual ... was that it was circumferential rather than up and down," Gagner said. Only linear, or "axial," cracks had been discovered previously in the nozzles that penetrate reactor vessels.

The new cracks were discovered in the welds around nozzles holding the control rods that slide in and out of the reactors. That makes the cracks more dangerous than other types because the nozzles are more likely to break loose from the vessel, she said.

None of the new circular cracks has been found at the San Onofre plant, a spokesman there said this week.

Nuclear reactors such as the two at the San Onofre nuclear plant along Interstate 5 between Oceanside and San Clemente have pressurized vessels about 40 feet tall made of thick steel that hold radioactive fuel rods submerged in water. Each pressurized vessel is penetrated by about 100 nozzles that hold control rods and other instrumentation.

The reactor's pressure vessel and its nozzles are within the concrete-and-steel dome built to withhold any radioactive release from the plant's primary coolant system.

The failure of a nozzle in an operating reactor would release large amounts of hot water that would flash to steam within the containment structure. Water from the primary system usually contains radioactive contamination. Federal regulators require nuclear plant operators to rehearse several times annually ways to handle any break in the reactor cooling system, though they say the chances of a large radioactive release are remote.

None of the circular cracks found so far at Oconee has allowed the penetration nozzles to break away, regulators said, though some water has leaked through the cracks.

"The problem is probably age-related," Gagner said. The Oconee plant began commercial operation in 1974.

Age-related degradation is one of the leading problems of the nuclear industry, according to critics such as the Nuclear Information Resource Service. Cracks are routinely repaired in reactor steam generators, and degradation has been found in other key components subject to extreme heat and pressure.

"The industry is plagued with age-related deterioration mechanisms unique to nuclear power operations," according to Paul Gunter, a researcher with Nuclear Information Resource Service, which regularly posts information at its Website at www.nirs.org.

"Chronic exposure to extreme radiation, heat, pressure, fatigue and corrosive chemistry are combining to cause embrittlement of metal, cracking, and erosion of components integral to the protection of the public's health and safety."

Nuclear industry officials have said problems such as cracking arise with age, but that those problems can be monitored and corrected with no significant risk to workers or the public.

San Onofre's operator, Southern California Edison Co., found and repaired linear cracks in reactor vessel nozzles in the Unit 3 reactor during routine refueling and maintenance work in 1997.

That reactor began commercial operation in 1984. The other operating San Onofre reactor, Unit 2, first went online in 1983.

The Unit 1 reactor, which operated from 1968 to 1992, is being demolished.

The reactor was retired to avoid the expense of costly additional safety upgrades required by federal regulators after the Three Mile Island accident in 1979 near Harrisburg, Pa.

Edison officials have not found cracks of any type in recent inspections of the reactor vessel, said plant spokesman Ray Golden.

"As a result of this (bulletin) we will do a more detailed inspection in the upcoming outages," Golden said, noting that Unit 2 is scheduled for refueling and maintenance next May, and Unit 3 is to start in January, 2003.

"Meanwhile, we normally monitor the entire system."

Detection systems within the plant allow operators to see a leak as low as two or three gallons per day in the 90,000-gallon primary cooling system, Golden said. That allows cracks to be identified before a leak becomes catastrophic.

The commission's bulletin went to the operators of all 69 commercial pressurized-water reactors in the United States. The pressurized-water reactors are designed to keep water in the primary coolant system pressurized so that it will not boil.

The primary coolant heats a secondary loop that turns to steam and spins the plant's electricity-generating turbines.

The country also has about 35 commercial boiling-water reactors, in which the primary coolant is allowed to turn to steam.

San Diego Gas & Electric Co. owns 20 percent of the two San Onofre reactors and distributes about 20 percent of the electricity produced there.

Contact staff writer Phil Diehl at (760) 901-4087 or pdiehl@nctimes.com.

8/13/01

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