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Re: lochbaum on nuke plant aging
From: Norman Cohen <ncohen12@HOME.COM>
>> by Lochbaum:
>> ------------------------------------------------------------------------
>>
>> Aging Nuclear Plants and License Renewal - Updated 09/13/2001
Just rhetoric; technically wrong. Seems intended to mislead.
Upgraded and maintained systems perform better now. Aging management
improves performance. Individual components subject to aging are
replaced/repaired. Better technology improves equipment/systems performance.
Jim
>> The NRC allows nuclear plant owners to cut back on the number of safety tests
>> and inspections. The NRC justifies this safety rollback on the notion that
>> experience demonstrates improved equipment reliability. But the fact remains
>> that nuclear plant equipment-just like virtually all living and inanimate
>> objects-follows what is called the "bathtub" curve. Region A, or the break-in
>> phase, and Region C, the wear-out phase, have high failure rates while Region
>> B reflects peak reliability during middle life. The NRC uses the lower
>> failure rate for equipment in Region B to relax testing intervals from once
>> per quarter to once per year. Mathematical magic then falsely "proves" safety
>> gains. For example, consider a component that fails every time it is tested.
>> Going from quarterly to annual tests reduces the number of failures per year
>> from four to one. On paper, safety is greatly improved. But in the plant,
>> safety is unchanged. Every nuclear plant in the United States is in Region B!
>> heading towards Region C, if it is not already into the wear-out phase.
>> Cutting back on safety checks saves plant owners money, but it may someday
>> cost lives.
>>
>> The NRC originally licensed nuclear plants for 40 years. Plant owners have
>> the option of seeking a 20-year extension. The Nuclear Regulatory Commission
>> (NRC) renews licenses after determining plant owners have aging management
>> programs to monitor the condition of important equipment and structures so
>> that repairs and/or replacements will take place to prevent failures. But
>> failures are simply not being prevented because many nuclear plants have been
>> forced to shut down since January 1, 2000, after aging equipment broke:
>>
>> 1. March 7, 2000: The owner reported that Nine Mile Point Unit 2 in New York
>> had automatically shut down when the system controlling the level of water
>> over the reactor core failed. The owner attributed the failure as
>> "Specifically, the manual-tracking card failed to provide an output signal
>> when the feedwater master controller was switched from automatic to manual
>> mode of operation ... The manual-tracking card failed due to aging."
>> [emphasis added]
>>
>> 2. March 14, 2000: The owner reported that Catawba Unit 1 in South Carolina
>> had automatically shut down due to an inadvertent electrical ground problem.
>> The owner reported "A detailed failure analysis determined that the root
>> cause of the connector failure was the misapplication of the connector insert
>> insulating material which is made of neoprene. ... The neoprene insert at the
>> failure point on the connector exhibits signs of accelerated aging [emphasis
>> added]. The inserts are hardened and there are charred deposits on the end of
>> the inserts which are indications of electrical tracking."
>>
>> 3. March 17, 2000: The owner reported that Indian Point Unit 2 in New York
>> had been forced to declare an emergency condition and shut down after a steam
>> generator tube failed and resulted in approximately 19,197 gallons leaking
>> from the reactor coolant system. The owner stated "Preliminary analysis
>> indicates that the cause of the tube failure is primary water stress
>> corrosion cracking (PWSCC)" [i.e., aging].
>>
>> 4. March 27, 2000: The owner reported that Catawba Unit 2 in South Carolina
>> had automatically shut down due to an inadvertent electrical ground problem.
>> The owner reported "A detailed failure analysis determined that the root
>> cause of the connector failure was the misapplication of the connector insert
>> insulating material which is made of neoprene. ... The neoprene insert at the
>> failure point on the connector exhibits signs of accelerated aging [emphasis
>> added]. The inserts are hardened and there are charred deposits on the end of
>> the inserts which are indications of electrical tracking."
>>
>> 5. September 12, 2000: The owner reported that Oyster Creek in New Jersey had
>> been forced to shut down because a system needed to provide containment
>> integrity had failed a periodic test. The owner determined "The cause of the
>> degradation in Secondary Containment was age-related degradation [emphasis
>> added] of the automatic ventilation exhaust valve seals."
>>
>> 6. September 27, 2000: The NRC reported that Diablo Canyon Unit 1 in
>> California had automatically shut down after an electrical transformer failed
>> and interrupted the supply of electricity to the reactor coolant pumps. The
>> NRC stated "The licensee's evaluation concluded that a center bus bar
>> overheated at a splice joint, which caused a polyvinyl chloride boot
>> insulator over the splice joint to smoke. Eventually, heat-induced failure of
>> fiberglass insulation on adjacent phases resulted in phase-to-phase arcing"
>> [i.e., aging].
>>
>> 7. February 16, 2001: The owner reported that North Anna Unit 2 in Virginia
>> had been forced to shut down due to leakage exceeding ten gallons per minute
>> from the reactor coolant system. The owner determined "The cause of the stem
>> packing material failure below the lantern ring is attributed to aging"
>> [emphasis added].
>>
>> 8. April 2, 2001: The owner reported that San Onofre Unit 3 in California
>> automatically shut down after an electrical breaker failed and started a
>> fire. The failed breaker was reportedly 25 years old and scheduled for
>> inspection next year. The owner "will implement modifications to appropriate
>> preventative maintenance [emphasis added] procedures to address the apparent
>> failure causes."
>>
>> 9. April 23, 2001: The owner reported that South Texas Project Unit 2 in
>> Texas had been forced to shut down after actions in the plant's electrical
>> switchyard tripped all three pumps supplying cooling water to the main
>> condenser. The pumps stopped running after workers took one electrical
>> circuit out of service thinking that a backup circuit was available to take
>> up the load. However, the backup circuit was also out of service because an
>> electrical breaker had remained opened after workers tried to close it. The
>> breaker's failure was attributed by the owner to "accelerated wear of the
>> components" [i.e., aging].
>>
>> 10. April 24, 2001: The owner reported that Limerick Unit 2 in Pennsylvania
>> had been forced to shut down when a pressure relief valve spuriously opened
>> and remained open. The owner attributed the failure to "a sudden loss of
>> material from the first stage pilot valve due to erosion and oxidation of the
>> Stellite disc material in the area of the seating surface" [i.e. aging]. The
>> owner additionally reported that "The SRV [safety relief valve] Leakage
>> Determination Monitoring Process did not consider all possible failure
>> mechanisms."
>>
>> 11. May 9, 2001: The owner reported that Beaver Valley Unit 2 in Pennsylvania
>> had automatically shut down after a motor-driven pump supplying cooling water
>> to the steam generator failed. The pump's failure was attributed by the owner
>> to "a combination of long term heating, accelerated oxidation [i.e., aging],
>> and marginal sizing of the motor cable and terminal lugs." [emphasis added]
>>
>> 12. July 17, 2001: The owner reported that Nine Mile Point Unit 2 in New York
>> had automatically shut down after a relay in the reactor protection system
>> failed. The relay manufacturer had notified its customers four years earlier
>> that the relay was vulnerable to oxide buildup [i.e., aging] and recommended
>> a modification to the relays along with periodic replacement. The owner opted
>> not to implement either recommendation; at least, not until after this event.
>>
>> 13. August 13, 2001: The owner reported that Beaver Valley Unit 1 in
>> Pennsylvania had been forced to shut down when the instrument air system
>> pressure declined to the point where air-operated valves throughout the plant
>> began closing. The owner attributed the pressure loss to "mechanical
>> aging/cyclic fatigue" of the spring in a valve that caused the output from
>> the air compressor to be vented rather than directed to the system piping.
>> [emphasis added]
>>
>> 14. August 14, 2001: The owner reported that the Kewaunee nuclear plant in
>> Wisconsin had automatically shut down due to insufficient instrument air
>> supply to the regulating valve for feedwater flow to the steam generator. The
>> regulating valve closed when the instrument air pressure dropped. The owner
>> attributed the air pressure loss to a tear in a neoprene diaphragm that had
>> not been detected due to a "running to failure" maintenance schedule. In
>> other words, the part wore out and broke.
>>
>> 15. August 20, 2001: The owner reported that the Perry nuclear plant in Ohio
>> had automatically shut down after a blown fuse stopped the flow of cooling
>> water to the reactor core. The owner determined that the fuse blew from high
>> electrical resistance "due to age related oxidation." [emphasis added]
>>
>> Nuclear power plants generate revenue by producing electricity. If their
>> owners are unable to properly maintain the equipment needed to make them
>> money, why should the public believe that they are able to properly maintain
>> the equipment needed to make us safe?
>>
>> September 13, 2001
>
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