Information Notice 2003-06, Failure of Safety-Related Linestarter Relays at San Onofre Nuclear Generating Station: Difference between revisions
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{{#Wiki_filter: | {{#Wiki_filter:UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, DC 20555-0001June 19, 2003NRC INFORMATION NOTICE 2003-06:FAILURE OF SAFETY-RELATED LINESTARTERRELAYS AT SAN ONOFRE NUCLEAR | ||
===GENERATING STATION=== | |||
==Addressees== | ==Addressees== | ||
All holders of operating licenses or construction permits for nuclear power reactors, exceptthose that have permanently ceased operations and have certified that fuel has been permanently removed from the reactor. | All holders of operating licenses or construction permits for nuclear power reactors, exceptthose that have permanently ceased operations and have certified that fuel has been | ||
permanently removed from the reactor. | |||
==Purpose== | ==Purpose== | ||
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to informaddressees of recent failures of safety-related valves due to linestarter relay | The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to informaddressees of recent failures of safety-related valves due to linestarter relay degradation. The | ||
degradation was caused by past use of excessive amounts of trichloroethane-based cleaners | |||
during preventive maintenance. It is expected that recipients will review the information for | |||
applicability to their facilities and consider actions, as appropriate, to avoid similar problems. | |||
However, suggestions in this information notice are not NRC requirements; therefore, no | |||
specific action or written response is required. | |||
==Description of Circumstances== | ==Description of Circumstances== | ||
San Onofre Nuclear Generating Station utilizes reversing linestarters manufactured by SquareD to operate the motors on safety-related motor-operated | San Onofre Nuclear Generating Station utilizes reversing linestarters manufactured by SquareD to operate the motors on safety-related motor-operated valves. The linestarter consists of | ||
"Inadequate Control of Paint and Cleaners for Safety Related Equipment," which the licensee performed in February | |||
based cleaner controls in place at the time of the information notice review, but overlooked the fact that safety-related equipment could have been damaged prior to the implementation of the controls in April | two relays that provide 480 volt power to the motor and contain auxiliary contacts associated | ||
with interlock and seal-in functions. The interlock function provides a means to avoid | |||
energizing both open and closed relays at the same time. The seal-in function keeps the relay | |||
energized until the valve has completed its stroke. All reversing linestarters have interlock | |||
auxiliary contacts. San Onofre has 172 Square D linestarters associated with safety-related | |||
motor-operated valves, 86 in each unit.On August 30, 2002, a Unit 3 low-pressure safety injection (LPSI) pump mini-recirculation valvefailed to open during surveillance testing. Subsequent analysis determined that the plastic | |||
housing on an auxiliary contact in the associated linestarter was degraded. The licensee | |||
determined that the auxiliary contact housing degradation was caused by the past use of | |||
excessive amounts of Inhibisol, a cleaning solvent based on trichloroethane (TCE). The | |||
cleaning solvent caused the plastic to break down. Over time, small amounts of the plastic | |||
came loose and interfered with the electrical contacts, resulting in the valve failure. In response to the LPSI pump mini-recirculation valve failure, San Onofre developed a plan toinspect a sample of other safety-related linestarters installed in Units 2 and 3. In October 2002, San Onofre completed the inspection of 19 additional linestarters. This sample inspection | |||
identified two auxiliary contacts that showed signs of chemical attack (i.e., cloudy plastic contact | |||
housing); however, both were found to be functional. Subsequently, the licensee developed a | |||
risk-informed plan to inspect all safety-related linestarters and replace all auxiliary contacts | |||
showing signs of chemical attack. The linestarter inspections were scheduled into online and | |||
outage maintenance windows, and will be completed by the end of the Unit 2 outage in 2004.On January 18, 2003, during a Unit 3 refueling outage, the quench tank sample containmentisolation valve failed to open during surveillance testing. Examination of the contact revealed | |||
that a similar chemical attack had occurred and caused the valve failure.On February 10, 2003, during an inspection of Unit 3 LPSI header stop valve linestarters, anauxiliary contact failed on the 20th cycle of the auxiliary contact test. The linestarter inspectionsincluded a test to cycle each auxiliary contact 20 times. This auxiliary contact cycle test was | |||
performed to determine the functionality of the auxiliary contacts in the linestarter.On Unit 3, all 86 linestarters have been inspected with two surveillance test failures noted andone maintenance test failure. The licensee replaced 42 auxiliary contacts from the linestarters | |||
due to evidence of chemical attack on the plastic auxiliary contact housing. On Unit 2, | |||
33 linestarters have been inspected as of May 2, 2003, with no failures noted; however, four | |||
auxiliary contacts showed signs of chemical attack on the plastic contact case.DiscussionAs a result of the valve stroke failure on August 30, 2002, the licensee initiated a laboratoryanalysis of the suspect auxiliary contact from the linestarter. The contact was coated with a | |||
plastic residue from the deterioration of the plastic switch bodies. The licensee concluded that | |||
excessive use of cleaning solvents during previous preventive maintenance activities had | |||
caused the failure of the contacts. The licensee believes that all damage to the auxiliary contact housings occurred prior to 1989and is showing up in the recent safety-related valve failures. The original linestarter preventive | |||
maintenance procedure was issued in April 1984, and required the use of cleaning solvents on | |||
linestarters, but had no caution regarding the potential for damage to plastic components within | |||
the linestarter. Also, the procedure did not require visual inspection of internally mounted | |||
auxiliary contact assemblies. As a result, Inhibisol was used liberally, which allowed the cleaner | |||
to come in contact with plastics that were susceptible to chemical degradation. In April 1989, the licensee recognized that TCE-based cleaners were being used improperly and that controls | |||
needed to be implemented to prevent future damage to equipment containing plastics. The | |||
licensee revised the consumables controls manual to restrict the use of TCE-based cleaners on | |||
plastics, and provided guidance on the approved method for use of the cleaner (i.e., spray on | |||
cloth, then wipe component). Additionally, the linestarter preventive maintenance procedure | |||
was revised to caution that cleaning solvents should be used sparingly to avoid damage to | |||
plastic components. In response to the recent valve failures, the licensee took action on | |||
March 7, 2003, to prohibit the use of all TCE-based cleaners for electrical maintenance | |||
applications. The licensee missed several opportunities from plant and industry experience to recognize theneed for an extent-of-condition review. An extent-of-condition review could have identified any | |||
equipment degradation that occurred throughout the plant due to improper use of cleaning | |||
solvents. One of these prior opportunities was the review of Information Notice 93-76, | |||
"Inadequate Control of Paint and Cleaners for Safety Related Equipment," which the licensee | |||
performed in February 1994. The review determined that the programs in place were sufficient | |||
to avoid problems similar to those discussed in the notice. The licensee focused on the TCE- | |||
based cleaner controls in place at the time of the information notice review, but overlooked the | |||
fact that safety-related equipment could have been damaged prior to the implementation of the | |||
controls in April 1989. This oversight was a missed opportunity to correct the equipment | |||
deficiency that has been revealed by the recent linestarter failures and the discovery of | |||
degraded contacts.The San Onofre linestarter experience emphasizes the need to perform an extent-of-conditionreview to determine equipment impact when an improper maintenance practice is recognized | |||
and corrected. Further, the root cause analysis revealed that past improper use of corrosive | |||
cleaners could result in degraded plant equipment that could remain undetected for a | |||
considerable length of time before showing up in equipment failures.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contacts | |||
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Program Director | |||
===Operating Reactor Improvements Program=== | |||
Division of Regulatory Improvement Programs | |||
Office of Nuclear Reactor RegulationTechnical Contacts:Gregory G. WarnickVern Hodge623-386-3638301-415-1861 Email:gxw2@nrc.govEmail: cvh@nrc.govAttachment: List of Recently Issued NRC Information Notices The licensee missed several opportunities from plant and industry experience to recognize theneed for an extent-of-condition review. An extent-of-condition review could have identified any | |||
equipment degradation that occurred throughout the plant due to improper use of cleaning | |||
solvents. One of these prior opportunities was the review of Information Notice 93-76, | |||
"Inadequate Control of Paint and Cleaners for Safety Related Equipment," which the licenseeperformed in February 1994. The review determined that the programs in place were sufficient | |||
to avoid problems similar to those discussed in the notice. The licensee focused on the TCE- | |||
based cleaner controls in place at the time of the information notice review, but overlooked the | |||
fact that safety-related equipment could have been damaged prior to the implementation of the | |||
controls in April 1989. This oversight was a missed opportunity to correct the equipment | |||
deficiency that has been revealed by the recent linestarter failures and the discovery of | |||
degraded contacts.The San Onofre linestarter experience emphasizes the need to perform an extent-of-conditionreview to determine equipment impact when an improper maintenance practice is recognized | |||
and corrected. Further, the root cause analysis revealed that past improper use of corrosive | |||
cleaners could result in degraded plant equipment that could remain undetected for a | |||
considerable length of time before showing up in equipment failures.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contacts | |||
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Program Director | |||
===Operating Reactor Improvements Program=== | |||
Division of Regulatory Improvement Programs | |||
Office of Nuclear Reactor RegulationTechnical Contacts:Gregory G. WarnickVern Hodge623-386-3638301-415-1861 Email:gxw2@nrc.govEmail: cvh@nrc.govAttachment: List of Recently Issued NRC Information NoticesDISTRIBUTION:ADAMS | |||
IN FileADAMS ACCESSION NUMBER:031700033DOCUMENT NAME: G:\RORP\OES\Staff Folders\Hodge\san_line inf.wpdOFFICEOES:RORP:DRIPTech EditorRIVEMCBNAMECVHodgePKleeneGWarnickKParcszewskiDATE06/10/200306/09/200306/12/200306/10/2003OFFICESC:OES:RORP:DRIPPD:RORP:DRIPNAMETReisWDBecknerDATE06/18/200306/19/2003OFFICIAL RECORD COPY | |||
______________________________________________________________________________________OL = Operating License | |||
CP = Construction PermitAttachment LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICES_____________________________________________________________________________________InformationDate of | |||
Notice No. SubjectIssuanceIssued to_____________________________________________________________________________________2003-05Failure to Detect FreespanCracks in PWR Steam | |||
Generator Tubes06/05/2003All holders of operating licensesor construction permits for | |||
pressurized-water reactors | |||
(PWRs).2002-15, Sup 1Potential HydrogenCombustion Events in BWR | |||
Piping05/06/2003All holders of operating licensesfor light water reactors, except | |||
those who have permanently | |||
ceased operations and have | |||
certified that fuel has been | |||
permanently removed from the | |||
reactor.2002-21, Sup 1Axial Outside-diameterCracking Affecting Thermally | |||
===Treated Alloy 600 Steam=== | |||
Generator Tubing04/01/2003All holders of operating licenseesfor nuclear power reactors, except those who have | |||
permanently ceased operations | |||
and have certified that fuel has | |||
been permanently removed from | |||
the reactor vessel.2003-04Summary of Fitness-For-DutyProgram Performance Reports | |||
for Calendar Year 200002/06/2003All holders of operating licenseesfor nuclear power reactors, except those who have | |||
permanently ceased operations | |||
and have certified that fuel has | |||
been permanently removed from | |||
the reactor vessel.2003-03Part 21 - Inadequately StakedCapscrew Renders Residual | |||
=== | ===Heat Removal Pump=== | ||
Inoperable01/27/2003All holders of operating licensesor construction permits for | |||
nuclear power reactors.Note:NRC generic communications may be received in electronic format shortly after they areissued by subscribing to the NRC listserver as follows:To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the followingcommand in the message portion:subscribe gc-nrr firstname lastname | |||
}} | |||
{{Information notice-Nav}} | {{Information notice-Nav}} |
Revision as of 18:36, 6 April 2018
ML031700033 | |
Person / Time | |
---|---|
Site: | San Onofre ![]() |
Issue date: | 06/19/2003 |
From: | Beckner W D NRC/NRR/DRIP/RORP |
To: | |
Hodge, CV, NRR/DRIP/RORP, (415-1861) | |
References | |
+sunsimjr=200611, -RFPFR IN-03-006 | |
Download: ML031700033 (5) | |
UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, DC 20555-0001June 19, 2003NRC INFORMATION NOTICE 2003-06:FAILURE OF SAFETY-RELATED LINESTARTERRELAYS AT SAN ONOFRE NUCLEAR
GENERATING STATION
Addressees
All holders of operating licenses or construction permits for nuclear power reactors, exceptthose that have permanently ceased operations and have certified that fuel has been
permanently removed from the reactor.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to informaddressees of recent failures of safety-related valves due to linestarter relay degradation. The
degradation was caused by past use of excessive amounts of trichloroethane-based cleaners
during preventive maintenance. It is expected that recipients will review the information for
applicability to their facilities and consider actions, as appropriate, to avoid similar problems.
However, suggestions in this information notice are not NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances
San Onofre Nuclear Generating Station utilizes reversing linestarters manufactured by SquareD to operate the motors on safety-related motor-operated valves. The linestarter consists of
two relays that provide 480 volt power to the motor and contain auxiliary contacts associated
with interlock and seal-in functions. The interlock function provides a means to avoid
energizing both open and closed relays at the same time. The seal-in function keeps the relay
energized until the valve has completed its stroke. All reversing linestarters have interlock
auxiliary contacts. San Onofre has 172 Square D linestarters associated with safety-related
motor-operated valves, 86 in each unit.On August 30, 2002, a Unit 3 low-pressure safety injection (LPSI) pump mini-recirculation valvefailed to open during surveillance testing. Subsequent analysis determined that the plastic
housing on an auxiliary contact in the associated linestarter was degraded. The licensee
determined that the auxiliary contact housing degradation was caused by the past use of
excessive amounts of Inhibisol, a cleaning solvent based on trichloroethane (TCE). The
cleaning solvent caused the plastic to break down. Over time, small amounts of the plastic
came loose and interfered with the electrical contacts, resulting in the valve failure. In response to the LPSI pump mini-recirculation valve failure, San Onofre developed a plan toinspect a sample of other safety-related linestarters installed in Units 2 and 3. In October 2002, San Onofre completed the inspection of 19 additional linestarters. This sample inspection
identified two auxiliary contacts that showed signs of chemical attack (i.e., cloudy plastic contact
housing); however, both were found to be functional. Subsequently, the licensee developed a
risk-informed plan to inspect all safety-related linestarters and replace all auxiliary contacts
showing signs of chemical attack. The linestarter inspections were scheduled into online and
outage maintenance windows, and will be completed by the end of the Unit 2 outage in 2004.On January 18, 2003, during a Unit 3 refueling outage, the quench tank sample containmentisolation valve failed to open during surveillance testing. Examination of the contact revealed
that a similar chemical attack had occurred and caused the valve failure.On February 10, 2003, during an inspection of Unit 3 LPSI header stop valve linestarters, anauxiliary contact failed on the 20th cycle of the auxiliary contact test. The linestarter inspectionsincluded a test to cycle each auxiliary contact 20 times. This auxiliary contact cycle test was
performed to determine the functionality of the auxiliary contacts in the linestarter.On Unit 3, all 86 linestarters have been inspected with two surveillance test failures noted andone maintenance test failure. The licensee replaced 42 auxiliary contacts from the linestarters
due to evidence of chemical attack on the plastic auxiliary contact housing. On Unit 2,
33 linestarters have been inspected as of May 2, 2003, with no failures noted; however, four
auxiliary contacts showed signs of chemical attack on the plastic contact case.DiscussionAs a result of the valve stroke failure on August 30, 2002, the licensee initiated a laboratoryanalysis of the suspect auxiliary contact from the linestarter. The contact was coated with a
plastic residue from the deterioration of the plastic switch bodies. The licensee concluded that
excessive use of cleaning solvents during previous preventive maintenance activities had
caused the failure of the contacts. The licensee believes that all damage to the auxiliary contact housings occurred prior to 1989and is showing up in the recent safety-related valve failures. The original linestarter preventive
maintenance procedure was issued in April 1984, and required the use of cleaning solvents on
linestarters, but had no caution regarding the potential for damage to plastic components within
the linestarter. Also, the procedure did not require visual inspection of internally mounted
auxiliary contact assemblies. As a result, Inhibisol was used liberally, which allowed the cleaner
to come in contact with plastics that were susceptible to chemical degradation. In April 1989, the licensee recognized that TCE-based cleaners were being used improperly and that controls
needed to be implemented to prevent future damage to equipment containing plastics. The
licensee revised the consumables controls manual to restrict the use of TCE-based cleaners on
plastics, and provided guidance on the approved method for use of the cleaner (i.e., spray on
cloth, then wipe component). Additionally, the linestarter preventive maintenance procedure
was revised to caution that cleaning solvents should be used sparingly to avoid damage to
plastic components. In response to the recent valve failures, the licensee took action on
March 7, 2003, to prohibit the use of all TCE-based cleaners for electrical maintenance
applications. The licensee missed several opportunities from plant and industry experience to recognize theneed for an extent-of-condition review. An extent-of-condition review could have identified any
equipment degradation that occurred throughout the plant due to improper use of cleaning
solvents. One of these prior opportunities was the review of Information Notice 93-76,
"Inadequate Control of Paint and Cleaners for Safety Related Equipment," which the licensee
performed in February 1994. The review determined that the programs in place were sufficient
to avoid problems similar to those discussed in the notice. The licensee focused on the TCE-
based cleaner controls in place at the time of the information notice review, but overlooked the
fact that safety-related equipment could have been damaged prior to the implementation of the
controls in April 1989. This oversight was a missed opportunity to correct the equipment
deficiency that has been revealed by the recent linestarter failures and the discovery of
degraded contacts.The San Onofre linestarter experience emphasizes the need to perform an extent-of-conditionreview to determine equipment impact when an improper maintenance practice is recognized
and corrected. Further, the root cause analysis revealed that past improper use of corrosive
cleaners could result in degraded plant equipment that could remain undetected for a
considerable length of time before showing up in equipment failures.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contacts
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Program Director
Operating Reactor Improvements Program
Division of Regulatory Improvement Programs
Office of Nuclear Reactor RegulationTechnical Contacts:Gregory G. WarnickVern Hodge623-386-3638301-415-1861 Email:gxw2@nrc.govEmail: cvh@nrc.govAttachment: List of Recently Issued NRC Information Notices The licensee missed several opportunities from plant and industry experience to recognize theneed for an extent-of-condition review. An extent-of-condition review could have identified any
equipment degradation that occurred throughout the plant due to improper use of cleaning
solvents. One of these prior opportunities was the review of Information Notice 93-76,
"Inadequate Control of Paint and Cleaners for Safety Related Equipment," which the licenseeperformed in February 1994. The review determined that the programs in place were sufficient
to avoid problems similar to those discussed in the notice. The licensee focused on the TCE-
based cleaner controls in place at the time of the information notice review, but overlooked the
fact that safety-related equipment could have been damaged prior to the implementation of the
controls in April 1989. This oversight was a missed opportunity to correct the equipment
deficiency that has been revealed by the recent linestarter failures and the discovery of
degraded contacts.The San Onofre linestarter experience emphasizes the need to perform an extent-of-conditionreview to determine equipment impact when an improper maintenance practice is recognized
and corrected. Further, the root cause analysis revealed that past improper use of corrosive
cleaners could result in degraded plant equipment that could remain undetected for a
considerable length of time before showing up in equipment failures.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contacts
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Program Director
Operating Reactor Improvements Program
Division of Regulatory Improvement Programs
Office of Nuclear Reactor RegulationTechnical Contacts:Gregory G. WarnickVern Hodge623-386-3638301-415-1861 Email:gxw2@nrc.govEmail: cvh@nrc.govAttachment: List of Recently Issued NRC Information NoticesDISTRIBUTION:ADAMS
IN FileADAMS ACCESSION NUMBER:031700033DOCUMENT NAME: G:\RORP\OES\Staff Folders\Hodge\san_line inf.wpdOFFICEOES:RORP:DRIPTech EditorRIVEMCBNAMECVHodgePKleeneGWarnickKParcszewskiDATE06/10/200306/09/200306/12/200306/10/2003OFFICESC:OES:RORP:DRIPPD:RORP:DRIPNAMETReisWDBecknerDATE06/18/200306/19/2003OFFICIAL RECORD COPY
______________________________________________________________________________________OL = Operating License
CP = Construction PermitAttachment LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICES_____________________________________________________________________________________InformationDate of
Notice No. SubjectIssuanceIssued to_____________________________________________________________________________________2003-05Failure to Detect FreespanCracks in PWR Steam
Generator Tubes06/05/2003All holders of operating licensesor construction permits for
pressurized-water reactors
(PWRs).2002-15, Sup 1Potential HydrogenCombustion Events in BWR
Piping05/06/2003All holders of operating licensesfor light water reactors, except
those who have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.2002-21, Sup 1Axial Outside-diameterCracking Affecting Thermally
Treated Alloy 600 Steam
Generator Tubing04/01/2003All holders of operating licenseesfor nuclear power reactors, except those who have
permanently ceased operations
and have certified that fuel has
been permanently removed from
the reactor vessel.2003-04Summary of Fitness-For-DutyProgram Performance Reports
for Calendar Year 200002/06/2003All holders of operating licenseesfor nuclear power reactors, except those who have
permanently ceased operations
and have certified that fuel has
been permanently removed from
the reactor vessel.2003-03Part 21 - Inadequately StakedCapscrew Renders Residual
Heat Removal Pump
Inoperable01/27/2003All holders of operating licensesor construction permits for
nuclear power reactors.Note:NRC generic communications may be received in electronic format shortly after they areissued by subscribing to the NRC listserver as follows:To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the followingcommand in the message portion:subscribe gc-nrr firstname lastname