Information Notice 1993-95, Storm-Related Loss of Offsite Power Events Due to Salt Buildup on Switchyard Insulators
UNITED STATES NUCLEAR REGULATORY
COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 December 13, 1993 NRC INFORMATION
NOTICE 93-95: STORM-RELATED
LOSS OF OFFSITE POWER EVENTS DUE TO SALT BUILDUP ON SWITCHYARD
INSULATORS
Addressees
All holders of operating
licensees
or construction
permits for nuclear power reactors located close to a large body of salt water.PurDose The U.S. Nuclear Regulatory
Commission (NRC) is issuing this information
notice to alert addressees
to the potential
for loss of offsite power due to salt contamination
of switchyard
insulators.
It is expected that recipients
will review the information
for applicability
to their facilities
and consider actions, as appropriate, to avoid similar problems.
However, no specific action or written response is required.Description
of Circumstances
On March 17, 1993, the Florida Power Corporation
Crystal River Unit 3 experienced
a loss of the 230 kV switchyard (normal offsite power to safety-related busses) when a light rain caused arcing across salt-laden
230 kV insulators
and opened breakers in the switchyard.
At the time, the unit was in cold shutdown during a maintenance
outage. The 'Al emergency
diesel generator
was used to power safety-related
loads including
shutdown cooling until the 230 kV switchyard
was restored.
The ABE emergency
diesel generator was unavailable
due to maintenance.
The 500 kV switchyard
supplied nonvital loads throughout
the event.On March 16 through 18, 1993, Carolina Power and Light Company's
Brunswick Units 1 and 2 experienced
a loss of the 230 kV switchyards (all offsite power)when light rain caused arcing across salt-laden
insulators
and opened breakers in the switchyard.
At the time, both units were in cold shutdown during an extended outage. Emergency
diesel generators
were used to power safety-related loads including
shutdown cooling until the offsite power was restored.Since 1982, the Boston Edison Company Pilgrim station has also experienced
several loss of offsite power events when heavy ocean storms deposited
salt on the 345 kV switchyard
causing the insulators
to arc to ground.9312070298
1P4 X tE N4 e, 9 3-95* 777 LAe~ffL.A~1241{3/f3P
K> k IN 93-95 December 13, 1993 Discussion
Intense and unusual storms on March 13 and 14, 1993, produced high tides and high winds (average of 80 to 97 kilometers/hour
high winds (50 to 60 miles/hour], with gusts up to 160 kilometers/hour
[100 miles/hour]
blowing ashore from the ocean i.e., Gulf of Mexico and Atlantic Ocean. These storms caused an unusual buildup of salt on the switchyard
insulators
at Crystal River Unit 3 and Brunswick
Units 1 and 2. The storms were unusual in that they included high winds but little or no precipitation.
As a result, salt from ocean spray built up on the switchyard
insulators
and was not washed away by rain.Days later, light rain increased
the electrical
conductivity
of the salt, resulting
in arcing across the insulators
at both sites. To remove the salt from the insulators, Florida Power Corporation
and Carolina Power and Light Company deenergized
the affected switchyards, washed the insulators
with high pressure demineralized
water, then returned the switchyards
to service. The washing stopped the electrical
arcing across the insulators.
The 500 kV switchyard
for Crystal River Unit 3 is located adjacent to the 230 kV switchyard.
It was relatively
unaffected.
The 500 kV switchyard
is used for main generator
output when Unit 3 is operating
and is used for an alternate
source of offsite power (i.e., backfeeding
of nonvital loads) during Unit 3 outages. The 500 kV switchyard
experienced
less arcing across the insulators
than the 230 kV switchyard
and no tripped breakers.
As a precautionary
measure, the licensee also deenergized
and washed the 500 kV switchyard
insulators.
Factors that may have reduced the storm inpact on the 500 kV switchyard
included location (farther away from the shore) and higher insulation
level (the 500 kV insulators
were designed for up to 700 kV operation
while the 230 kV insulators
were designed for up to 242 kV operation).
In addition, the licensee observed that, of the two types of 230 kV insulators
installed, the newer post type had less arcing than the older cap and pin type.Licensee followup action in response to these events, to improve the future performance
of non-safety
equipment, included:
investigating
available
salt buildup monitoring
systems, evaluating
insulator
washing methods/capabilities, considering
the use of room temperature
vulcanized (RTV)silicon rubber coatings, installing
newer metal oxide gapless surge arrestors to replace older silicon carbide gap type surge arrestors, and replacing cellon-treated
wood transmission
towers.The 345 kV switchyard
insulators
at Pilgrim were coated with RTV silicon rubber (Sylgard)
in 1987. It was expected that the RTV coating, when applied in 1987, would be effective
for a period of 15 years. However, actual experience
at Pilgrim indicates
that the coating is effective
for a much
`- IN 93-95 December 13, 1993 shorter period of time. Consequently, the Insulators
at Pilgrim were cleaned and coated with RTV again during the spring 1993 refueling
outage. As a long-term option, the licensee is considering
a replacement
of the existing 345 kV switchyard
with a modern compactly
designed switchyard
which would be more resistant
to the coastal environment.
These events illustrate
the significance
of maintaining
reliable offsite and onsite power sources during outages as well as during operation.
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 Regulation (NRR) project manager.Bran .Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, RII (404) 331-7288 P. Holmes-Ray, RII (904) 795-7677 P. Kang, NRR (301) 504-2779 R. Prevatte, RII (919) 457-9531 Attachment:
List of Recently Issued NRC Information
Notices
Attachment
IN 93-95 December 13, 1993 LIST OF RECENTLY ISSUED NRC INFORMATION
NOTICES Informati
on Date of Notice No. Subject Issuance Issued to 93-94 93-93 93-92 91-21, Supp. 1 89-77, Supp. 1 93-91 Unauthorized
Forced Entry into the Pro-tected Area at Three Mile Island Unit 1 on February 7, 1993 Inadequate
Control of Reactor Coolant System Conditions
During Shutdown Plant Improvements
to Mitigate Common Depend-encies in Component Cooling Water Systems Inadequate
Quality Assurance
Program of Vendor Supplying Safety-Related
Equipment Debris in Containment
Emergency
Sumps and Incorrect
Screen Configurations
Misadjustment
Between General Electric 4.16-KV Circuit Breakers and Their Associated
Cubicles Unisolatable
Reactor Coolant System Leak Following
Repeated Applications
of Leak Sealant 12/09/93 12/08/93 12/07/93 12/07/93 12/03/93 12/03/93 12/01/93 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors and all recipients
of NUREG-0040, "License Con-tractor and Vendor Inspec-tion Status Report" (White Book).All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.93-90 OL -Operating
License CP -Construction
Permit
IN 93-95 December 13, 1993 shorter period of time. Consequently, the Insulators
at Pilgrim were cleaned and coated with RTV again during the spring 1993 refueling
outage. As a long-term option, the licensee is considering
a replacement
of the existing 345 kV switchyard
with a modern compactly
designed switchyard
which would be more resistant
to the coastal environment.
These events Illustrate
the significance
of onsite power sources during outages as well maintaining
reliable offsite and as during operation.
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 Regulation (NRR) project manager.OgItf Ognefw 5 Brian K. Grimeg Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, RII (404) 331-7288 P. Holmes-Ray, RII (904) 795-7677 P. Kang, NRR (301) 504-2779 R. Prevatte, RII (919) 457-9531 Attachment:
List of Recently Issued NRC Information
Notices*SEE PREVIOUS CONCURRENCE
OFFICE *RII *TECH ED *EELB *C:EELB:NRR
NAME RSchin JBeeson PKang CBerlinger
DATE _07/13/93
08/09/93 11/03/93 /03/93 I_ 77 1 10 nlnr*OGCB!DORS
- C:OGCB:DORS
JTWiggins
NECampbell
GHMarcus / /IIIl 11/04/93 11/18/93 1 1/23/93 12/1'5/93 1L OUMtNi NAIt: Ns-V*.zN
IN 93-XX December xx, 1993 shorter period of time. Consequently, the insulators
at Pilgrim were cleaned and coated with protective
RTV coating again during the spring 1993 refueling outage. As an alternate
long term option, the licensee is considering
a replacement
of the existing 345 kV switchyard
with a modern compactly
designed switchyard
which would be more resistant
to the coastal environment.
These events illustrate
the significance
of maintaining
reliable offsite and onsite power sources during outages as well as during operation.
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 Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, R11 (404) 331-7288 P. Holmes-Ray, (904) 795-7677 RII P. Kang, NRR (301) 504-2779 R. Prevatte, RII (919) 457-9531 Attachment:
List of Recently Issued NRC Information
Notices*SEE PREVIOUS CONCURRENCE
OFFICE *RII *TECH ED *EELB *C:EELB:NRR
NAME RSchin JBeeson PKang CBerlinger
DATE 07/13/93 -08/09/93
,11/03/93
11/03/93 D: DE I *OGCB:DORS
- C:OGCB:DORS
D: DORS JTWiggins
NECampbell
l GHMarcus BKGrimes l 11/04/93 11/18/93 11/23/93 112/ /93-J r UCLUMNI NAMt: bWIl1H1N.NMC
/Wr PD
IN 93-XX November xx, 1993 NRC review of these events concluded
that the safety-related
equipment
at the affected units performed
as designed and there were no increased
risks to the public.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 Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, RII (404) 331-7288 P. Holmes-Ray, RII (904) 795-7677 P. Kang, NRR (301) 504-2779 R. Prevatte, R11 (919) 457-9531 Attachment:
List of Recently Issued NRC Information
Notices*SEE PREVIOUS CONCURRENCE
OFFICE *RII *TECH ED *EELB *C:EELB:NRR
NAME RSchin JBeeson PKang CBerlinger
DATE J07/13/93 o08/09/93 i11/03/930, 11/03/93 1I~1*D: DE*OGCB:DORS
C:OGCB:DORS
D: DORS JTWiggins
NECampbell
GHMarcus BKGrimes L 11/04/93 111/18/93
11/Z/93 11/ /93-------------DOCUMENT NAME: SWITCHIN.NEC
IN 93-XX November xx, 1993 NRC review of these events concluded
that the safety-related
equipment
at the affected units performed
as designed and there were no increased
risks to the public.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 Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, RII (404) 331-7288 P. Kang, NRR (301) 504-2779 P. Holmes-Ray, SRI, Crystal River (904) 795-7677 R. Prevatte, SRI, Brunswick (919) 457-9531 Attachment:
List of Recently Issued NRC Information
Notices*SEE PREVIOUS CANCUIRRFNCr
-OFFICE *RII *TECH ED *EELB *C:EELB:NRR
NAME RSchin JBeeson PKang CBerlinger
DATE 07/13/93 08/09/93 11/03/93 11/03/93 D: DE OGCB:DORS c:OGCB:RSfl
n-nnl* z JTWiggins
N ECampbell
GHMacus BKGrimes 11/04/93 11/1!/93 'f I II/ /93 II/ /93 1flPkrilIT ,k*IAr- tLI .-n UUvUtICNI
MIAMEi: 3Wl1tlnrN.NLLv
7Vt C , I,/-? d2., Pe ~z no,& AAW&WetfA.
7 IN 93-XX November xx, 1993 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 Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, RII (404) 331-7288 P. Holmes-Ray, SRI, Crystal River (904) 795-7677 R. Prevatte, SRI, Brunswick (919) 457-9531 Attachment:
List of Recently Issued NRC Information
Notices*SEE PREVIOUS CONCURRENCE
OFFICE *RII *TECH ED *EELB *C:EELB:NRR
NAME RSchin JBeeson PKang CBerlinger
DATE 1 07/13/93 -08/09/93 11/03/93 ,11/03/93 D:DE OGCB:DORS C:OGCB:DORS
D:DORS JTWiggins
l NECampbell
GHMarcus BKGrimes A / f/9/ /93 -9I/ /93 U/ /93 DOCUME 3E: SWITCHIN.NEC
IN 93-XX August xx, 1993 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 Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, RII (404) 331-7288 P. Holmes-Ray, SRI, Crystal River (904) 795-7677 R. Prevatte, SRI, Brunswick (919) 457-9531 di 6 4'I o. .erg BUD. II Attachment:
List of Recently Issued NRC*SFF PREVIOUS CONCURRENCE
Information
Notices--- -I____ I- __ I_ ., -n e OFFICE *RII W' I ttLLx LLL; "Ir I V, NAME RSchin JBeeson VS/ PKang CBerlinger
DATE 07/13/ 93 093 ________ __93 __# _ _/93--39 nffF I Onrr FtlORS C !OGCR :DORS D: DORS vI o .-.__ ____ ._ _JTWiggins
NECampbell
GHMarcus BKGrimes 08/ /93 08/ /93 08/ /93 08/ /93 DOCUMENT NAML: SMILHIN.iLL
- w-IN 93-XX August xx, 1993 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 Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: R. Schin, RII (404) 331-5561 P. Fillion, RII (404) 331-7288 P. Holmes-Ray, SRI, Crystal River (904) 795-7677 R. Prevatte, SRI, Brunswick (919) 457-9531 Attachment:
List of Recently Issued NRC Information
Notices*SFF PREVIOUS CONCURRENCE
OFFICE RII *TECH ED EELB C:EELB:NRR
NAME .RSchin JBeeson SSaba (I .¢ CBerlinger
DATE ______08/7
/93 08/ /93 08/ /93-~.1 D: DE OGCB:DORS C:OGCB:DORS
D: DORS JTWiggins
NECampbell
GHMarcus BKGrimes 08/ /93 08/ /93 08/ /93 1 08/ /93 DOCUMENT NAME: SWITCHIN.NEC