Information Notice 2003-06, Failure of Safety-Related Linestarter Relays at San Onofre Nuclear Generating Station: Difference between revisions
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| issue date = 06/19/2003 | | issue date = 06/19/2003 | ||
| title = Failure of Safety-Related Linestarter Relays at San Onofre Nuclear Generating Station | | title = Failure of Safety-Related Linestarter Relays at San Onofre Nuclear Generating Station | ||
| author name = Beckner W | | author name = Beckner W | ||
| author affiliation = NRC/NRR/DRIP/RORP | | author affiliation = NRC/NRR/DRIP/RORP | ||
| addressee name = | | addressee name = | ||
Line 15: | Line 15: | ||
| page count = 5 | | page count = 5 | ||
}} | }} | ||
{{#Wiki_filter:UNITED | {{#Wiki_filter:UNITED STATES | ||
NUCLEAR REGULATORY COMMISSION | |||
OFFICE OF NUCLEAR REACTOR REGULATION | |||
WASHINGTON, DC 20555-0001 June 19, 2003 NRC INFORMATION NOTICE 2003-06: FAILURE OF SAFETY-RELATED LINESTARTER | |||
RELAYS AT SAN ONOFRE NUCLEAR | |||
GENERATING STATION | |||
==Addressees== | ==Addressees== | ||
All holders of operating licenses or construction permits for nuclear power reactors, | All holders of operating licenses or construction permits for nuclear power reactors, except | ||
those that have permanently ceased operations and have certified that fuel has been | |||
permanently removed from the reactor. | permanently removed from the reactor. | ||
==Purpose== | ==Purpose== | ||
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to | The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to inform | ||
addressees 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 | degradation was caused by past use of excessive amounts of trichloroethane-based cleaners | ||
during preventive maintenance. | 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. | applicability to their facilities and consider actions, as appropriate, to avoid similar problems. | ||
Line 38: | Line 50: | ||
==Description of Circumstances== | ==Description of Circumstances== | ||
San Onofre Nuclear Generating Station utilizes reversing linestarters manufactured by | San Onofre Nuclear Generating Station utilizes reversing linestarters manufactured by Square | ||
D 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 | two relays that provide 480 volt power to the motor and contain auxiliary contacts associated | ||
with interlock and seal-in functions. | with interlock and seal-in functions. The interlock function provides a means to avoid | ||
energizing both open and closed relays at the same time. | 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. | energized until the valve has completed its stroke. All reversing linestarters have interlock | ||
auxiliary contacts. | auxiliary contacts. San Onofre has 172 Square D linestarters associated with safety-related | ||
motor-operated valves, 86 in each unit. | motor-operated valves, 86 in each unit. | ||
housing on an auxiliary contact in the associated linestarter was degraded. | On August 30, 2002, a Unit 3 low-pressure safety injection (LPSI) pump mini-recirculation valve | ||
failed 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 | 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). | 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 to | |||
inspect 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 | identified two auxiliary contacts that showed signs of chemical attack (i.e., cloudy plastic contact | ||
housing); however, both were found to be functional. | 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 | risk-informed plan to inspect all safety-related linestarters and replace all auxiliary contacts | ||
showing signs of chemical attack. | 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. | 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 containment | |||
isolation valve failed to open during surveillance testing. Examination of the contact revealed | |||
due to evidence of chemical attack on the plastic auxiliary contact housing. | 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, an | |||
auxiliary contact failed on the 20th cycle of the auxiliary contact test. The linestarter inspections | |||
included 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 and | |||
one 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 | 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. | auxiliary contacts showed signs of chemical attack on the plastic contact case. | ||
Discussion | |||
As a result of the valve stroke failure on August 30, 2002, the licensee initiated a laboratory | |||
analysis of the suspect auxiliary contact from the linestarter. The contact was coated with a | |||
plastic residue from the deterioration of the plastic switch bodies. | 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 | 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 | caused the failure of the contacts. | ||
The licensee believes that all damage to the auxiliary contact housings occurred prior to 1989 and 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 | maintenance procedure was issued in April 1984, and required the use of cleaning solvents on | ||
Line 94: | Line 135: | ||
linestarters, but had no caution regarding the potential for damage to plastic components within | linestarters, but had no caution regarding the potential for damage to plastic components within | ||
the linestarter. | the linestarter. Also, the procedure did not require visual inspection of internally mounted | ||
auxiliary contact assemblies. | 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. | 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. | 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 | licensee revised the consumables controls manual to restrict the use of TCE-based cleaners on | ||
Line 106: | Line 147: | ||
plastics, and provided guidance on the approved method for use of the cleaner (i.e., spray on | plastics, and provided guidance on the approved method for use of the cleaner (i.e., spray on | ||
cloth, then wipe component). | 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 | was revised to caution that cleaning solvents should be used sparingly to avoid damage to | ||
plastic components. | 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 | 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 | applications. The licensee missed several opportunities from plant and industry experience to recognize the | ||
need 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 | equipment degradation that occurred throughout the plant due to improper use of cleaning | ||
solvents. | 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. | performed in February 1994. The review determined that the programs in place were sufficient | ||
to avoid problems similar to those discussed in the notice. | 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 | 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 | fact that safety-related equipment could have been damaged prior to the implementation of the | ||
controls in April 1989. | 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 | 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- | degraded contacts. | ||
The San Onofre linestarter experience emphasizes the need to perform an extent-of-condition | |||
and corrected. | review 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 | cleaners could result in degraded plant equipment that could remain undetected for a | ||
considerable length of time before showing up in equipment failures. | considerable length of time before showing up in equipment failures. | ||
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Program Director | This information notice requires no specific action or written response. If you have any | ||
questions 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 | Division of Regulatory Improvement Programs | ||
Office of Nuclear Reactor | Office of Nuclear Reactor Regulation | ||
Technical Contacts: Gregory G. Warnick Vern Hodge | |||
623-386-3638 301-415-1861 Email: gxw2@nrc.gov Email: cvh@nrc.gov | |||
Attachment: List of Recently Issued NRC Information Notices | |||
031700033 DOCUMENT NAME: G:\RORP\OES\Staff Folders\Hodge\san_line inf.wpd | |||
OFFICE OES:RORP:DRIP Tech Editor RIV EMCB | |||
NAME CVHodge PKleene GWarnick KParcszewski | |||
DATE 06/10/2003 06/09/2003 06/12/2003 06/10/2003 OFFICE SC:OES:RORP:DRIP PD:RORP:DRIP | |||
NAME TReis WDBeckner | |||
DATE 06/18/2003 06/19/2003 | |||
Attachment LIST OF RECENTLY ISSUED | |||
NRC INFORMATION NOTICES | |||
_____________________________________________________________________________________ | |||
Information Date of | |||
Notice No. Subject Issuance Issued to | |||
_____________________________________________________________________________________ | |||
2003-05 Failure to Detect Freespan 06/05/2003 All holders of operating licenses | |||
Cracks in PWR Steam or construction permits for | |||
pressurized-water reactors | Generator Tubes pressurized-water reactors | ||
(PWRs). | (PWRs). | ||
2002-15, Sup 1 Potential Hydrogen 05/06/2003 All holders of operating licenses | |||
those who have permanently | Combustion Events in BWR for light water reactors, except | ||
Piping those who have permanently | |||
ceased operations and have | ceased operations and have | ||
Line 173: | Line 249: | ||
permanently removed from the | permanently removed from the | ||
reactor.2002-21, Sup | reactor. | ||
2002-21, Sup 1 Axial Outside-diameter 04/01/2003 All holders of operating licensees | |||
Cracking Affecting Thermally for nuclear power reactors, Treated Alloy 600 Steam except those who have | |||
permanently ceased operations | Generator Tubing permanently ceased operations | ||
and have certified that fuel has | and have certified that fuel has | ||
Line 184: | Line 261: | ||
been permanently removed from | been permanently removed from | ||
the reactor vessel. | the reactor vessel. | ||
2003-04 Summary of Fitness-For-Duty 02/06/2003 All holders of operating licensees | |||
Program Performance Reports for nuclear power reactors, for Calendar Year 2000 except those who have | |||
permanently ceased operations | permanently ceased operations | ||
Line 194: | Line 273: | ||
been permanently removed from | been permanently removed from | ||
the reactor vessel.2003- | the reactor vessel. | ||
2003-03 Part 21 - Inadequately Staked 01/27/2003 All holders of operating licenses | |||
Capscrew Renders Residual or construction permits for | |||
Heat Removal Pump nuclear power reactors. | |||
Inoperable | |||
Note: NRC generic communications may be received in electronic format shortly after they are | |||
issued by subscribing to the NRC listserver as follows: | |||
To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the following | |||
command in the message portion: | |||
subscribe gc-nrr firstname lastname | |||
= | ______________________________________________________________________________________ | ||
OL = Operating License | |||
CP = Construction Permit}} | |||
{{Information notice-Nav}} | {{Information notice-Nav}} |
Latest revision as of 02:47, 24 November 2019
ML031700033 | |
Person / Time | |
---|---|
Site: | San Onofre |
Issue date: | 06/19/2003 |
From: | Beckner W NRC/NRR/DRIP/RORP |
To: | |
Hodge, CV, NRR/DRIP/RORP, (415-1861) | |
References | |
+sunsimjr=200611, -RFPFR IN-03-006 | |
Download: ML031700033 (5) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, DC 20555-0001 June 19, 2003 NRC INFORMATION NOTICE 2003-06: FAILURE OF SAFETY-RELATED LINESTARTER
RELAYS AT SAN ONOFRE NUCLEAR
GENERATING STATION
Addressees
All holders of operating licenses or construction permits for nuclear power reactors, except
those 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 inform
addressees 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 Square
D 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 valve
failed 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 to
inspect 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 containment
isolation 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, an
auxiliary contact failed on the 20th cycle of the auxiliary contact test. The linestarter inspections
included 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 and
one 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.
Discussion
As a result of the valve stroke failure on August 30, 2002, the licensee initiated a laboratory
analysis 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 1989 and 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 the
need 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-condition
review 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 any
questions 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 Regulation
Technical Contacts: Gregory G. Warnick Vern Hodge
623-386-3638 301-415-1861 Email: gxw2@nrc.gov Email: cvh@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
031700033 DOCUMENT NAME: G:\RORP\OES\Staff Folders\Hodge\san_line inf.wpd
OFFICE OES:RORP:DRIP Tech Editor RIV EMCB
NAME CVHodge PKleene GWarnick KParcszewski
DATE 06/10/2003 06/09/2003 06/12/2003 06/10/2003 OFFICE SC:OES:RORP:DRIP PD:RORP:DRIP
NAME TReis WDBeckner
DATE 06/18/2003 06/19/2003
Attachment LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________________
Information Date of
Notice No. Subject Issuance Issued to
_____________________________________________________________________________________
2003-05 Failure to Detect Freespan 06/05/2003 All holders of operating licenses
Cracks in PWR Steam or construction permits for
Generator Tubes pressurized-water reactors
(PWRs).
2002-15, Sup 1 Potential Hydrogen 05/06/2003 All holders of operating licenses
Combustion Events in BWR for light water reactors, except
Piping those who have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.
2002-21, Sup 1 Axial Outside-diameter 04/01/2003 All holders of operating licensees
Cracking Affecting Thermally for nuclear power reactors, Treated Alloy 600 Steam except those who have
Generator Tubing permanently ceased operations
and have certified that fuel has
been permanently removed from
the reactor vessel.
2003-04 Summary of Fitness-For-Duty 02/06/2003 All holders of operating licensees
Program Performance Reports for nuclear power reactors, for Calendar Year 2000 except those who have
permanently ceased operations
and have certified that fuel has
been permanently removed from
the reactor vessel.
2003-03 Part 21 - Inadequately Staked 01/27/2003 All holders of operating licenses
Capscrew Renders Residual or construction permits for
Heat Removal Pump nuclear power reactors.
Note: NRC generic communications may be received in electronic format shortly after they are
issued by subscribing to the NRC listserver as follows:
To subscribe send an e-mail to <listproc@nrc.gov >, no subject, and the following
command in the message portion:
subscribe gc-nrr firstname lastname
______________________________________________________________________________________
OL = Operating License
CP = Construction Permit