Information Notice 1991-29, Deficiencies Identifie During Electrical Distribution System Functional Inspections: Difference between revisions

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| issue date = 04/15/1991
| issue date = 04/15/1991
| title = Deficiencies Identifie During Electrical Distribution System Functional Inspections
| title = Deficiencies Identifie During Electrical Distribution System Functional Inspections
| author name = Rossi C E
| author name = Rossi C
| author affiliation = NRC/NRR
| author affiliation = NRC/NRR
| addressee name =  
| addressee name =  
Line 14: Line 14:
| page count = 10
| page count = 10
}}
}}
{{#Wiki_filter:4AUNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555April 15, 1991NRC INFORMATION NOTICE NO. 91-29: DEFICIENCIES IDENTIFIED DURING ELECTRICALDISTRIBUTION SYSTEM FUNCTIONAL INSPECTIONS
{{#Wiki_filter:4 A
 
===UNITED STATES===
NUCLEAR REGULATORY COMMISSION
 
===OFFICE OF NUCLEAR REACTOR REGULATION===
WASHINGTON, D.C.
 
20555
 
===April 15, 1991===
NRC INFORMATION NOTICE NO. 91-29:  
 
===DEFICIENCIES IDENTIFIED DURING ELECTRICAL===
DISTRIBUTION SYSTEM FUNCTIONAL INSPECTIONS


==Addressees==
==Addressees==
:All holders of operating licenses or construction permits for nuclear powerreactors.
:
All holders of operating licenses or construction permits for nuclear power
 
reactors.


==Purpose==
==Purpose==
:This information notice is intended to alert addressees to deficiencies identi-fied during recently performed electrical distribution system functionalinspections (EDSFIs). It is expected that recipients will review the informa-tion for applicability to their facilities and consider actions, as appropri-ate, to avoid similar problems. However, suggestions contained in thisinformation notice do not constitute NRC requirements; therefore, no specificaction or written response is required.
:
This information notice is intended to alert addressees to deficiencies identi- fied during recently performed electrical distribution system functional
 
inspections (EDSFIs).
 
It is expected that recipients will review the informa- tion for applicability to their facilities and consider actions, as appropri- ate, to avoid similar problems.
 
===However, suggestions contained in this===
information notice do not constitute NRC requirements; therefore, no specific
 
action or written response is required.


==Description of Circumstances==
==Description of Circumstances==
:During multidisciplinary inspections, the U.S. Nuclear Regulatory Commission(NRC) has identified many deficiencies related to tWeelectrical distributionsystem. To address these deficiencies, the NRC has developed an inspection tospecifically evaluate the electrical distribution system. During the lastyear, the NRC completed eight EDSFIs, performing at least one in each of thefive NRC geographical regions. During these inspections, the staff foundseveral common deficiencies in the licensees' programs and in the electricaldistribution systems as designed and configured at each plant. These deficien-cies included inadequate ac voltages at the 480 Vac and 120 Vac distributionlevels, inadequate procedures to test circuit breakers, and inadequate determi-nations and evaluations of setpoints.Discussion:Inadequate VoltageDuring inspections conducted at the San Onofre Nuclear Generating Station(Inspection Reports 50-361/89-200 and 50-362/89-200), the Susquehanna SteamElectric Station (Inspection Reports 50-387/90-200 and 50-388/90-200), and the9104090124
:
' JIN 91-29April 15, 1991 Waterford Steam Electric Station (Inspection Report 50-382/90-23), the stafffound that, under certain conditions, the voltage available at the safety buseswould be inadequate to Operate safety-related loads and associated equipment.These conditions could occur when the plan~t's electrical distribution systemswere being supplied from an offsite grid that had become degraded but thatcontinued to supply voltages that remained above the setpoints at which thedegraded grid relays would be activated.At San Onofre, the numerous voltage drops throughout the system could cause thevoltage to 120 Vaciontactors to drop below the-voltage range for which thesecontactors were certified as acceptable by their manufacturers. To resolvethis problem the licensee has performed testing that established a loweracceptable voltage range for this equipment.At Susquehanna, the degraded grid relay setpoint'was'set at 84 percent on the4160 Yac buses. Th'i's setpoint could have allowed inadequate voltage to be-delivered to numerous safety-related loads at both the 480 Vac and 120 Vaclevels. The licensee calculated that setpoints'of at least 93 percent would berequired to ensure adequate voTtage to all safety-related equipment. Toresolve this problem, the lice'isee has raised the setpoints of the degradedgrid relays and has initiated a modification to install 120 Vac regulatingtransformers.At the Waterford nuclear plant, the degraded grid relays were set at87.5 percent'as sensed on the'4160 Vac buses. :Although this setting was foundto be marginally adequate-'for-equipment connected to the 4160 Vac buses, thesetting was too low to ensure that adequate v6ltage would'be maintained at the480 Vac and 120 Vac levels. The licensee is 6e4aluating solutions to thisproblem and has instituted a procedure- to manually'separate from the grid ifthe voltage falls to unacceptable levels but remains above the relay setpoints.The function of the degraded grid relays is to en'sure that adequate voltage isavailable tooperate all Class lE loads at all distribution levels. In orderto ensure-that all required' Class E 'loads will remain operable during degradedvoltage conditions, some licensees are currently'reanalyzing the basis for thedegraded grid relay setpoints. The new analyses consider all required Class 1Eloads and include the assumption that the voltage on the buses being sensed bythese relays can remain at a level just above the relay setpoints.Inadequate Circuit Breaker Testing ProceduresDuring recent EDSFIs ahd previously on other NRC inspections, the staff identi-fied repetitive deficiencies in licensees' programs to test circuit breakers.These deficiencies included inadequate procedures, inadequate test acceptancecriteria, inadequate test equipment, and inadequate control of testing. At theSusquehanna plant (Inspection Reports 50-387/90-200 and 50-388/90-200), thestaff found that the licensee was testing dc molded case circuit breakers witha procedure written for testing ac breakers. The licensee had not establishedspecific acceptance criteria for the dc breaker IN 91-29April 15, 1991 At the Shearon Harris Nuclear Power Plant (Inspection Report 50-400/90-200),the staff identified that the licensee was.testing molded case circuit breakersagainst National Electrical Manufacturers Association (NEMA),acceptance crite-ria, which were less stringent than the manufacturer's time-current curves forthese breakers. In addition, the staff identified that the licensee wastesting 480 V air circuit breakers with test equipment that applied a testsignal (secondary injection) to the solid state trip units in the circuitbreakers. Although this method adequately verified that the trip units func-tioned properly, it did not verify that the breaker's current transformerfunctioned properly or that the wiring and connectors were adequate between thecurrent transformer and the solid state trip units. Other licensees haveperformed testing by primary current injection or by individually checking eachcomponent of the circuit breaker, including the wiring and connectors todemonstrate that the circuit breaker functions properly.Inadequate Determinations and Evaluations of SetpointsMany of the findings identified during recent EDSFIs were related to inadequatesetpoint determinations. Useful guidance for determining setpoints is providedby Instrument Society of America Standard 67.04-1982, "Setpoints for NuclearSafety-Related Instrumentation used in Nuclear Power Plants," which the NRCstaff has endorsed by Regulatory Guide 1.105 Revision 2 -1986, "InstrumentSetpoints for Safety-Related Systems." This guidance applies both to processinstrumentation and, in part, to certain relays that perform a safety function.Some licensees have operated equipment outside of acceptable limits becausethey did not determine proper setpoints and did not evaluate and account forinstrument drift. Operating the equipment under these conditions couldcompromise the safety functions of the equipment. The staff has identifiedthese circumstances primarily for those instruments in which the licensee hasdetermined the setpoints as opposed to those instruments for which thesetpoints were determined by the architect/engineer or the nuclear safetysystem supplier. Those setpoints not contained in the plant technical specifi-cations were also more frequently found to be deficient. During recent EDSFIs,the staff identified deficiencies in setpoints for diesel day tank levelindicators, diesel air start compressor controllers and alarms, inverter lowvoltage shutdown circuitry, degraded grid relays, and diesel overcurrentrelays.In addition to identifying deficiencies in the setpoints themselves, the NRChas determined that not all the licensees are typically verifying that themagnitude of instrument drift that was assumed in the original setpoint calcu-lation coincides with the magnitude of drift observed in the plant. Somelicensees have corrected this deficiency by verifying the magnitude of instru-ment drift by trending, (comparing "as found" calibration data to previous "asleft" data). This is particularly important for the degraded grid relaysetpoints, which often require very tight calibration tolerance bands, and forwhich very low drift values are often assume v-IN 91-29April 15, 1991 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate NRR project manager.Charles E. Rossi, eirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
During multidisciplinary inspections, the U.S. Nuclear Regulatory Commission
 
(NRC) has identified many deficiencies related to tWeelectrical distribution
 
system. To address these deficiencies, the NRC has developed an inspection to
 
specifically evaluate the electrical distribution system. During the last
 
year, the NRC completed eight EDSFIs, performing at least one in each of the
 
five NRC geographical regions. During these inspections, the staff found
 
several common deficiencies in the licensees' programs and in the electrical
 
distribution systems as designed and configured at each plant. These deficien- cies included inadequate ac voltages at the 480 Vac and 120 Vac distribution
 
levels, inadequate procedures to test circuit breakers, and inadequate determi- nations and evaluations of setpoints.
 
Discussion:
 
===Inadequate Voltage===
During inspections conducted at the San Onofre Nuclear Generating Station
 
(Inspection Reports 50-361/89-200 and 50-362/89-200), the Susquehanna Steam
 
Electric Station (Inspection Reports 50-387/90-200 and 50-388/90-200), and the
 
9104090124
 
' J
 
IN 91-29 April 15, 1991 Waterford Steam Electric Station (Inspection Report 50-382/90-23), the staff
 
found that, under certain conditions, the voltage available at the safety buses
 
would be inadequate to Operate safety-related loads and associated equipment.
 
These conditions could occur when the plan~t's electrical distribution systems
 
were being supplied from an offsite grid that had become degraded but that
 
continued to supply voltages that remained above the setpoints at which the
 
degraded grid relays would be activated.
 
At San Onofre, the numerous voltage drops throughout the system could cause the
 
voltage to 120 Vaciontactors to drop below the-voltage range for which these
 
contactors were certified as acceptable by their manufacturers.
 
To resolve
 
this problem the licensee has performed testing that established a lower
 
acceptable voltage range for this equipment.
 
At Susquehanna, the degraded grid relay setpoint'was'set at 84 percent on the
 
4160 Yac buses.
 
Th'i's setpoint could have allowed inadequate voltage to be
 
-delivered to numerous safety-related loads at both the 480 Vac and 120 Vac
 
levels. The licensee calculated that setpoints'of at least 93 percent would be
 
required to ensure adequate voTtage to all safety-related equipment. To
 
resolve this problem, the lice'isee has raised the setpoints of the degraded
 
grid relays and has initiated a modification to install 120 Vac regulating
 
transformers.
 
At the Waterford nuclear plant, the degraded grid relays were set at
 
87.5 percent'as sensed on the'4160 Vac buses. :Although this setting was found
 
to be marginally adequate-'for-equipment connected to the 4160 Vac buses, the
 
setting was too low to ensure that adequate v6ltage would'be maintained at the
 
480 Vac and 120 Vac levels. The licensee is 6e4aluating solutions to this
 
problem and has instituted a procedure- to manually'separate from the grid if
 
the voltage falls to unacceptable levels but remains above the relay setpoints.
 
The function of the degraded grid relays is to en'sure that adequate voltage is
 
available tooperate all Class lE loads at all distribution levels.
 
In order
 
to ensure-that all required' Class E 'loads will remain operable during degraded
 
voltage conditions, some licensees are currently'reanalyzing the basis for the
 
degraded grid relay setpoints. The new analyses consider all required Class 1E
 
loads and include the assumption that the voltage on the buses being sensed by
 
these relays can remain at a level just above the relay setpoints.
 
===Inadequate Circuit Breaker Testing Procedures===
During recent EDSFIs ahd previously on other NRC inspections, the staff identi- fied repetitive deficiencies in licensees' programs to test circuit breakers.
 
These deficiencies included inadequate procedures, inadequate test acceptance
 
criteria, inadequate test equipment, and inadequate control of testing. At the
 
Susquehanna plant (Inspection Reports 50-387/90-200 and 50-388/90-200), the
 
staff found that the licensee was testing dc molded case circuit breakers with
 
a procedure written for testing ac breakers. The licensee had not established
 
specific acceptance criteria for the dc breakers.
 
IN 91-29 April 15, 1991 At the Shearon Harris Nuclear Power Plant (Inspection Report 50-400/90-200),
the staff identified that the licensee was.testing molded case circuit breakers
 
against National Electrical Manufacturers Association (NEMA),acceptance crite- ria, which were less stringent than the manufacturer's time-current curves for
 
these breakers. In addition, the staff identified that the licensee was
 
testing 480 V air circuit breakers with test equipment that applied a test
 
signal (secondary injection) to the solid state trip units in the circuit
 
breakers.
 
Although this method adequately verified that the trip units func- tioned properly, it did not verify that the breaker's current transformer
 
functioned properly or that the wiring and connectors were adequate between the
 
current transformer and the solid state trip units. Other licensees have
 
performed testing by primary current injection or by individually checking each
 
component of the circuit breaker, including the wiring and connectors to
 
demonstrate that the circuit breaker functions properly.
 
Inadequate Determinations and Evaluations of Setpoints
 
Many of the findings identified during recent EDSFIs were related to inadequate
 
setpoint determinations. Useful guidance for determining setpoints is provided
 
by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear
 
Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC
 
staff has endorsed by Regulatory Guide 1.105 Revision 2 -
1986, "Instrument
 
Setpoints for Safety-Related Systems." This guidance applies both to process
 
instrumentation and, in part, to certain relays that perform a safety function.
 
Some licensees have operated equipment outside of acceptable limits because
 
they did not determine proper setpoints and did not evaluate and account for
 
instrument drift. Operating the equipment under these conditions could
 
compromise the safety functions of the equipment. The staff has identified
 
these circumstances primarily for those instruments in which the licensee has
 
determined the setpoints as opposed to those instruments for which the
 
setpoints were determined by the architect/engineer or the nuclear safety
 
system supplier. Those setpoints not contained in the plant technical specifi- cations were also more frequently found to be deficient. During recent EDSFIs, the staff identified deficiencies in setpoints for diesel day tank level
 
indicators, diesel air start compressor controllers and alarms, inverter low
 
voltage shutdown circuitry, degraded grid relays, and diesel overcurrent
 
relays.
 
In addition to identifying deficiencies in the setpoints themselves, the NRC
 
has determined that not all the licensees are typically verifying that the
 
magnitude of instrument drift that was assumed in the original setpoint calcu- lation coincides with the magnitude of drift observed in the plant. Some
 
licensees have corrected this deficiency by verifying the magnitude of instru- ment drift by trending, (comparing "as found" calibration data to previous "as
 
left" data). This is particularly important for the degraded grid relay
 
setpoints, which often require very tight calibration tolerance bands, and for
 
which very low drift values are often assumed.
 
v- IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If
 
you have any questions about the information in this notice, please contact the
 
technical contact listed below or the appropriate NRR project manager.
 
===Charles E. Rossi, eirector===
Division of Operational Events Assessment
 
===Office of Nuclear Reactor Regulation===


===Technical Contact:===
===Technical Contact:===
Jeffrey B. Jacobson, NRR(301) 492-0996


===Attachment:===
===Jeffrey B. Jacobson, NRR===
List of Recently Issued NRC Information Noticesi Attachment 1IN 91-29April 15, 1991 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to91-2891-2789-90,Supp. 191-2691-2591-2491-23Cracking in FeedwaterSystem PipingIncorrect Rotation ofPositive Displacement PumpPressurizer Safety ValveLift Setpoint ShiftPotential NonconservativeErrors in the Working FormatHansen-Roach Cross-SectionSet Provided with The Kenoand Scale CodesCommercial-Grade StructuralFraming Components SuppliedAs Nuclear Safety-RelatedEquipmentRecent Operating ExperienceInvolving Reactor OperationWithout A Licensed ReactorOperator or Senior ReactorOperator Present in theControl RoomAccidental Radiation Over-exposures to Personnel Due toIndustrial Radiography Acces-sory Equipment Malfunctions04/15/91 All holders of OLs orCPs for pressurizedwater reactors (PWRs).04/10/91 All holders of OLs orCPs for nuclear powerreactors.04/10/91 All holders of OLs orCPs for nuclear powerreactors.04/02/91 All fuel cycle licenseesand other licensees, in-cluding all holders ofoperating licenses fornuclear power reactors,who use physics codes tosupport criticalitysafety in the use offissile material.04/01/91 All holders of OLs orCPs for nuclear powerreactors.03/26/91 All holders of OLs orCPs for nuclear power,test, and research re-actors, and all Part 55licensed operators.03/26/91 All Nuclear RegulatoryCommission (NRC) licens-ees authorized to usesealed sources for indus-trial radiography.OL = Operating LicenseCP = Construction Permit IN 91-29April 15, 1991 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate NRR project manager.O6ginal agen& byCharles E. Ross!Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices
 
i
 
===Attachment 1===
IN 91-29
 
===April 15, 1991 LIST OF RECENTLY ISSUED===
NRC INFORMATION NOTICES
 
Information
 
Date of
 
Notice No.
 
Subject
 
Issuance
 
Issued to
 
91-28
91-27
89-90,
Supp. 1
91-26
91-25
91-24
91-23
 
===Cracking in Feedwater===
System Piping
 
===Incorrect Rotation of===
Positive Displacement Pump
 
===Pressurizer Safety Valve===
Lift Setpoint Shift
 
===Potential Nonconservative===
Errors in the Working Format
 
Hansen-Roach Cross-Section
 
===Set Provided with The Keno===
and Scale Codes
 
Commercial-Grade Structural
 
===Framing Components Supplied===
As Nuclear Safety-Related
 
Equipment
 
===Recent Operating Experience===
Involving Reactor Operation
 
===Without A Licensed Reactor===
Operator or Senior Reactor
 
===Operator Present in the===
Control Room
 
Accidental Radiation Over- exposures to Personnel Due to
 
Industrial Radiography Acces- sory Equipment Malfunctions
 
04/15/91  
 
===All holders of OLs or===
CPs for pressurized
 
water reactors (PWRs).
 
04/10/91  
 
===All holders of OLs or===
CPs for nuclear power
 
reactors.
 
04/10/91  
 
===All holders of OLs or===
CPs for nuclear power
 
reactors.
 
04/02/91  
 
===All fuel cycle licensees===
and other licensees, in- cluding all holders of
 
operating licenses for
 
nuclear power reactors, who use physics codes to
 
support criticality
 
safety in the use of
 
fissile material.
 
04/01/91  
 
===All holders of OLs or===
CPs for nuclear power
 
reactors.
 
03/26/91  
 
===All holders of OLs or===
CPs for nuclear power, test, and research re- actors, and all Part 55 licensed operators.
 
03/26/91  
 
===All Nuclear Regulatory===
Commission (NRC) licens- ees authorized to use
 
sealed sources for indus- trial radiography.
 
OL = Operating License
 
CP = Construction Permit
 
IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If
 
you have any questions about the information in this notice, please contact the
 
technical contact listed below or the appropriate NRR project manager.
 
O6ginal agen& by
 
Charles E. Ross!
 
===Charles E. Rossi, Director===
Division of Operational Events Assessment
 
===Office of Nuclear Reactor Regulation===


===Technical Contact:===
===Technical Contact:===
Jeffrey B. Jacobson, NRR(301) 492-0996


===Attachment:===
===Jeffrey B. Jacobson, NRR===
List of Recently Issued NRC Information Notices*SEE PREVIOUS04/ fI9OGC :DOEA: RRPCWen04/ /91CONCURRENCES*C/OGCB:DOEA:NRR*RPB:ADM *C/SICB:DST:NRRCHBerlinger TechEd SNewberry04/08/91 03/20/91 03/18/91*RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRIS:NRRJBJacobson:bt EVImbro WDLanning02/08/91 02/08/91 02/19/91*C/SELB:DST:NRRFRosa03/18/91*D/DRIS:NRRBKGrimes02/27/91  
(301) 492-0996 Attachment:
*- I IN 91-XXApril xx, 1991 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
 
===List of Recently Issued NRC Information Notices===
*SEE PREVIOUS
 
04/ fI9 OGC :DOEA: RR
 
PCWen
 
04/  
/91
 
===CONCURRENCES===
*C/OGCB:DOEA:NRR*RPB:ADM
 
*C/SICB:DST:NRR
 
CHBerlinger
 
TechEd
 
SNewberry
 
04/08/91  
03/20/91  
03/18/91
*RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRIS:NRR
 
JBJacobson:bt
 
EVImbro
 
WDLanning
 
02/08/91  
02/08/91  
02/19/91
*C/SELB:DST:NRR
 
FRosa
 
03/18/91
*D/DRIS:NRR
 
BKGrimes
 
02/27/91
 
*- I
 
IN 91-XX
 
April xx, 1991 This information notice requires no specific action or written response. If
 
you have any questions about the information in this notice, please contact the
 
technical contact listed below or the appropriate NRR project manager.
 
===Charles E. Rossi, Director===
Division of Operational Events Assessment
 
===Office of Nuclear Reactor Regulation===


===Technical Contact:===
===Technical Contact:===
Jeffrey B. Jacobson, NRR(301) 492-0996List of Recently Issued NRC Information Notices


===Attachment:===
===Jeffrey B. Jacobson, NRR===
*SEE PREVIOUS CONCURRENCES *C/SICB:DST:NRRD/DOEA:NRR C/OGCB:DO T*RPB:Ad SNewBerryCERossi Y- CHBerling rjw TechEd04/ /91 04/8/91 03/20/91 03/18/91,c CB:DOEA:NRR *RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRISNRR4CvPvWen JBJacobson:bt EVImbro WMLanning04/cl/91 02/08/91 02/08/91 02/19/91*C/SELB:DST:NRRFRosa03/18/91*D/DRIS:NRRBKGrimes02/27/91 IN 91-XXMarch xx, 1991 Inadequate Determinations and Evaluations of SetpointsMany of the findings identified during recent EDSFIs related to inadequatesetpoint determinations. Useful guidance for determining setpoints is providedby Instrument Society of America Standard 67.04-1982, "Setpoints for NuclearSafety-Related Instrumentation used in Nuclear Power Plants," which the NRCstaff has endorsed by Regulatory Guide 1.105 Revision 2 -1986, "InstrumentSetpoints for Safety-Related Systems." This guidance applies both to processinstrumentation and, in part, to certain relays that perform a safety function.Licensees have operated equipment outside of acceptable limits because they didnot determine proper setpoints and did not evaluate and account for instrumentdrifts. Operating the equipment under these conditions could compromise thesafety functions of the equipment. The staff has identified these circum-stances primarily for those instruments in which the licensee has determinedthe setpoints as opposed to those instruments for which the setpoints weredetermined by the architect/engineer or the nuclear safety system supplier.Those setpoints not contained in the plant technical specifications were alsomore frequently found to be deficient. During recent EDSFIs, the staffidentified deficiencies in setpoints for diesel day tank level indicators,diesel air start compressor controllers and alarms, inverter low voltageshutdown circuitry, degraded grid relays, and diesel overcurrent relays.In addition to identifying deficiencies in the setpoints themselves, the NRChas determined that licensees are not typically verifying that the magnitudeof instrument drift that was assumed in the original setpoint calculationcoincides with the magnitude of drift observed in the plant. Licensee canverify the magnitude of instrument drift by trending, (comparing 'as found"calibration data to previous 'as left" data). This is particularly importantfor the degraded grid relay setpoints, which often require very tight calibra-tion tolerance bands, and for which very low drift values are often assumed.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
(301) 492-0996
 
===List of Recently Issued NRC Information Notices===
Attachment:
*SEE PREVIOUS CONCURRENCES
 
*C/SICB:DST:NRR
 
D/DOEA:NRR
 
C/OGCB:DO
 
T*RPB:Ad
 
SNewBerry
 
CERossi Y-  
 
===CHBerling rjw TechEd===
04/ /91  
04/8/91  
03/20/91  
03/18/91
,c
 
CB:DOEA:NRR *RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRISNRR
 
4CvPvWen
 
JBJacobson:bt
 
EVImbro
 
WMLanning
 
04/cl/91  
02/08/91  
02/08/91  
02/19/91
*C/SELB:DST:NRR
 
FRosa
 
03/18/91
*D/DRIS:NRR
 
BKGrimes
 
02/27/91
 
IN 91-XX
 
March xx, 1991 Inadequate Determinations and Evaluations of Setpoints
 
Many of the findings identified during recent EDSFIs related to inadequate
 
setpoint determinations. Useful guidance for determining setpoints is provided
 
by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear
 
Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC
 
staff has endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument
 
Setpoints for Safety-Related Systems." This guidance applies both to process
 
instrumentation and, in part, to certain relays that perform a safety function.
 
Licensees have operated equipment outside of acceptable limits because they did
 
not determine proper setpoints and did not evaluate and account for instrument
 
drifts. Operating the equipment under these conditions could compromise the
 
safety functions of the equipment. The staff has identified these circum- stances primarily for those instruments in which the licensee has determined
 
the setpoints as opposed to those instruments for which the setpoints were
 
determined by the architect/engineer or the nuclear safety system supplier.
 
Those setpoints not contained in the plant technical specifications were also
 
more frequently found to be deficient. During recent EDSFIs, the staff
 
identified deficiencies in setpoints for diesel day tank level indicators, diesel air start compressor controllers and alarms, inverter low voltage
 
shutdown circuitry, degraded grid relays, and diesel overcurrent relays.
 
In addition to identifying deficiencies in the setpoints themselves, the NRC
 
has determined that licensees are not typically verifying that the magnitude
 
of instrument drift that was assumed in the original setpoint calculation
 
coincides with the magnitude of drift observed in the plant.
 
===Licensee can===
verify the magnitude of instrument drift by trending, (comparing 'as found"
calibration data to previous 'as left" data). This is particularly important
 
for the degraded grid relay setpoints, which often require very tight calibra- tion tolerance bands, and for which very low drift values are often assumed.
 
This information notice requires no specific action or written response. If
 
you have any questions about the information in this notice, please contact the
 
technical contact listed below or the appropriate NRR project manager.
 
===Charles E. Rossi, Director===
Division of Operational Events Assessment
 
===Office of Nuclear Reactor Regulation===


===Technical Contact:===
===Technical Contact:===
Jeffrey B. Jacobson, NRR(301) 492-0996


===Attachment:===
===Jeffrey B. Jacobson, NRR===
RPB:ADMTechEd* imJa03/20/91 PRSIB:DRISJBdacobson*:t02/08/91List of Recently Issued NRC Information NoticesC:OGCB:UOEA D:DOEA *See previous cCHBerlinger CERossi1 03/l/91 03/ /91oncurrencebtSC:RSIB:DRISEVImbro*02/08/91C:RSIB:DRISWDLanning*02/19/91D:DRISBKGrimes*02/27/91C:SELB:DSTFRosa*03/18/91C:SICB:DSTSNewberry*03/18/91  
(301) 492-0996 Attachment:
; -IN 91-XXJanuary xx, 1991 Inadequate Setpoint Determinations and EvaluationsMany of the findings identified during recent EDSFIs were related to inadequatesetpoint determinations. In order to properly determine an appropriateinstrument setpoint, all associated inaccuracies and tolerances must beaccounted for. Useful guidance for determining setpoints is provided by ISA67.04-1982, "Setpoints for Nuclear Safety-Related Instrumentation used inNuclear Power Plants' which has been endorsed by Regulatory Guide 1.105Revision 2 -1986, "Instrument Setpoints for Safety Related Systems". Thisguidance is applicable not Just for instrumentation but is also applicable forcertain relays and other control oriented pieces of equipment.The setpoint problem has been identified primarily with those instruments inwhich the licensee has determined the setpoints as opposed to those setpointsdetermined by the NSSS vendor. Those setpoints not contained in the planttechnical specifications are also likely to be suspect. During recent EDSFIs,deficiencies in setpoints related to diesel day tank level indicators, dieselair start compressor controllers and alarms, invertor low voltage shutdowncircuitry, degraded grid relays, and diesel overcurrent relays have beenidentified.In addition to the deficiencies identified in the setpoints themselves, the NRChas determined that licensees are not typically verifying that the magnitude ofsetpoint drift that was assumed in the original setpoint calculation is indeedcorrect. This verification can be performed by trending, i.e., by comparing"as found" calibration data to previous "as left" data. This is particularlyimportant for the degraded grid setpoints where very tight calibrationtolerance bands are often required and where very low drift values are oftenassumed. Failure to evaluate and account for instrument drifts has led to theoperation of equipment outside of acceptable limits which could compromise thesafety functions of the equipment.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
RPB:ADM
 
TechEd* imJa
 
03/20/91 P
 
RSIB:DRIS
 
JBdacobson*:t
 
02/08/91
 
===List of Recently Issued NRC Information Notices===
C:OGCB:UOEA
 
D:DOEA
 
*See previous c
 
CHBerlinger
 
CERossi
 
1 03/l/91  
03/ /91 oncurrence
 
bt
 
SC:RSIB:DRIS
 
EVImbro*
02/08/91 C:RSIB:DRIS
 
WDLanning*
02/19/91 D:DRIS
 
BKGrimes*
02/27/91 C:SELB:DST
 
FRosa*
03/18/91 C:SICB:DST
 
SNewberry*
03/18/91
 
;  
-
IN 91-XX
 
January xx, 1991 Inadequate Setpoint Determinations and Evaluations
 
Many of the findings identified during recent EDSFIs were related to inadequate
 
setpoint determinations. In order to properly determine an appropriate
 
instrument setpoint, all associated inaccuracies and tolerances must be
 
accounted for. Useful guidance for determining setpoints is provided by ISA
 
67.04-1982, "Setpoints for Nuclear Safety-Related Instrumentation used in
 
Nuclear Power Plants' which has been endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument Setpoints for Safety Related Systems". This
 
guidance is applicable not Just for instrumentation but is also applicable for
 
certain relays and other control oriented pieces of equipment.
 
The setpoint problem has been identified primarily with those instruments in
 
which the licensee has determined the setpoints as opposed to those setpoints
 
determined by the NSSS vendor. Those setpoints not contained in the plant
 
technical specifications are also likely to be suspect. During recent EDSFIs, deficiencies in setpoints related to diesel day tank level indicators, diesel
 
air start compressor controllers and alarms, invertor low voltage shutdown
 
circuitry, degraded grid relays, and diesel overcurrent relays have been
 
identified.
 
In addition to the deficiencies identified in the setpoints themselves, the NRC
 
has determined that licensees are not typically verifying that the magnitude of
 
setpoint drift that was assumed in the original setpoint calculation is indeed
 
correct. This verification can be performed by trending, i.e., by comparing
 
"as found" calibration data to previous "as left" data. This is particularly
 
important for the degraded grid setpoints where very tight calibration
 
tolerance bands are often required and where very low drift values are often
 
assumed. Failure to evaluate and account for instrument drifts has led to the
 
operation of equipment outside of acceptable limits which could compromise the
 
safety functions of the equipment.
 
This information notice requires no specific action or written response. If
 
you have any questions about the information in this notice, please contact the
 
technical contact listed below or the appropriate NRR project manager.
 
===Charles E. Rossi, Director===
Division of Operational Events Assessment
 
===Office of Nuclear Reactor Regulation===


===Technical Contact:===
===Technical Contact:===
Jeffrey B. Jacobson, NRR(301) 492-0996


===Attachment:===
===Jeffrey B. Jacobson, NRR===
List of Recently Issued NRC Information Notices*See previous concurrenceRPB:ADM C:OGCB:DOEA D:DOEATechEd CHBerlinger CERossi02/ /91 02/ /91 02/ /91 Xrt"RSIB:DRIS SC:RSIB:DRIS C: S C:S C:SIJBJacobson*:bt EVImbro* WD ng mes FRoV-rW SNe rry02/08/91 02/08/91 024 7/91 02/t7/91 "- / 91O/91 IN 91-XXJanuary xx, 1991 Inadequate Setpoint Determinations and EvaluationsMany of the findings identified during recent EDSFIs were related to inadequatesetpoint determinations. In order to properly determine an appropriateinstrument setpoint, all associated inaccuracies and tolerances must beaccounted for. Guidance for setpoint determinations is given in ANSI StandardS67.04-1988, 'Setpoints for Nuclear Safety-Related Instrumentation." Thisguidance is applicable not Just for instrumentation but is also applicable forcertain relays and other control oriented pieces of equipment.The setpoint problem is most prevalent for those instruments in which thelicensee has determined the setpoints as opposed to those setpoints determinedby the NSSS vendor. Those setpoints not contained in the plant technicalspecifications are also likely to be suspect. During recent EDSFIs, defi-ciencies in setpoints related to diesel day tank level indicators, diesel airstart compressor controllers and alarms, invertor low voltage shutdowncircuitry, degraded grid relays, and diesel overcurrent relays have beenidentified.In addition to the deficiencies identified in the setpoints themselves, the NRChas determined that licensees are not typically verifying that the magnitude ofsetpoint drift that was assumed in the original setpoint calculation is indeedcorrect. This verification can be performed by trending, i.e., by comparing"as found" calibration data to previous "as left" data. This is particularlyimportant for the degraded grid rely setpoints where very tight calibrationtolerance bands are often required and where very low drift values are oftenassumed. Failure to evaluate and account for instrument drifts has led to theoperation of equipment outside of acceptable limits which could compromise thesafety functions of the equipment.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor Regulation
(301) 492-0996 Attachment:  
 
===List of Recently Issued NRC Information Notices===
*See previous concurrence
 
RPB:ADM
 
C:OGCB:DOEA
 
D:DOEA
 
TechEd
 
CHBerlinger
 
CERossi
 
02/ /91  
02/ /91  
02/ /91 Xrt"
RSIB:DRIS
 
SC:RSIB:DRIS
 
C:  
S
 
C:S
 
C:SI
 
JBJacobson*:bt EVImbro*  
WD
 
ng
 
mes
 
FRoV-rW
 
SNe
 
rry
 
02/08/91  
02/08/91  
024 7/91  
02/t7/91 "-  
/ 91O/91
 
IN 91-XX
 
January xx, 1991 Inadequate Setpoint Determinations and Evaluations
 
Many of the findings identified during recent EDSFIs were related to inadequate
 
setpoint determinations. In order to properly determine an appropriate
 
instrument setpoint, all associated inaccuracies and tolerances must be
 
accounted for. Guidance for setpoint determinations is given in ANSI Standard
 
S67.04-1988, 'Setpoints for Nuclear Safety-Related Instrumentation." This
 
guidance is applicable not Just for instrumentation but is also applicable for
 
certain relays and other control oriented pieces of equipment.
 
The setpoint problem is most prevalent for those instruments in which the
 
licensee has determined the setpoints as opposed to those setpoints determined
 
by the NSSS vendor. Those setpoints not contained in the plant technical
 
specifications are also likely to be suspect. During recent EDSFIs, defi- ciencies in setpoints related to diesel day tank level indicators, diesel air
 
start compressor controllers and alarms, invertor low voltage shutdown
 
circuitry, degraded grid relays, and diesel overcurrent relays have been
 
identified.
 
In addition to the deficiencies identified in the setpoints themselves, the NRC
 
has determined that licensees are not typically verifying that the magnitude of
 
setpoint drift that was assumed in the original setpoint calculation is indeed
 
correct. This verification can be performed by trending, i.e., by comparing
 
"as found" calibration data to previous "as left" data. This is particularly
 
important for the degraded grid rely setpoints where very tight calibration
 
tolerance bands are often required and where very low drift values are often
 
assumed. Failure to evaluate and account for instrument drifts has led to the
 
operation of equipment outside of acceptable limits which could compromise the
 
safety functions of the equipment.
 
This information notice requires no specific action or written response. If
 
you have any questions about the information in this notice, please contact the
 
technical contact listed below or the appropriate NRR project manager.
 
===Charles E. Rossi, Director===
Division of Operational Events Assessment
 
===Office of Nuclear Reactor Regulation===


===Technical Contact:===
===Technical Contact:===
Jeffrey B. Jacobson, NRR(301) 492-0996


===Attachment:===
===Jeffrey B. Jacobson, NRR===
List of Recently Issued NRC Information NoticesRPB:ADM C:OGCB:DOEA D:DOEATechEd CHBerlinger CERossi02/ /91 02/ /91 02/ /91RSIB: SC:RX RIS C:RSIB:DRIS D:DRIS C:SELB:DST C:SICB:DSTJBJac 6n:bt EVIm 'J>' WDLanning BKGrimes FRosa SNewberry020 A' 02/djz1 02/ /91 02/ /91 02/ /91 02/ /91}}
(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices
 
RPB:ADM
 
C:OGCB:DOEA
 
D:DOEA
 
TechEd
 
CHBerlinger
 
CERossi
 
02/ /91  
02/ /91  
02/ /91 RSIB:  
SC:RX
 
RIS
 
C:RSIB:DRIS
 
D:DRIS
 
C:SELB:DST
 
C:SICB:DST
 
JBJac 6n:bt EVIm 'J>'  
WDLanning
 
BKGrimes
 
FRosa
 
SNewberry
 
020 A'  
02/djz1  
02/ /91  
02/ /91  
02/ /91  
02/ /91}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Latest revision as of 10:17, 16 January 2025

Deficiencies Identifie During Electrical Distribution System Functional Inspections
ML031190636
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane  
Issue date: 04/15/1991
From: Rossi C
Office of Nuclear Reactor Regulation
To:
References
IN-91-029, NUDOCS 9104090124
Download: ML031190636 (10)
v • d • e


4 A

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555

April 15, 1991

NRC INFORMATION NOTICE NO. 91-29:

DEFICIENCIES IDENTIFIED DURING ELECTRICAL

DISTRIBUTION SYSTEM FUNCTIONAL INSPECTIONS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is intended to alert addressees to deficiencies identi- fied during recently performed electrical distribution system functional

inspections (EDSFIs).

It is expected that recipients will review the informa- tion for applicability to their facilities and consider actions, as appropri- ate, to avoid similar problems.

However, suggestions contained in this

information notice do not constitute NRC requirements; therefore, no specific

action or written response is required.

Description of Circumstances

During multidisciplinary inspections, the U.S. Nuclear Regulatory Commission

(NRC) has identified many deficiencies related to tWeelectrical distribution

system. To address these deficiencies, the NRC has developed an inspection to

specifically evaluate the electrical distribution system. During the last

year, the NRC completed eight EDSFIs, performing at least one in each of the

five NRC geographical regions. During these inspections, the staff found

several common deficiencies in the licensees' programs and in the electrical

distribution systems as designed and configured at each plant. These deficien- cies included inadequate ac voltages at the 480 Vac and 120 Vac distribution

levels, inadequate procedures to test circuit breakers, and inadequate determi- nations and evaluations of setpoints.

Discussion:

Inadequate Voltage

During inspections conducted at the San Onofre Nuclear Generating Station

(Inspection Reports 50-361/89-200 and 50-362/89-200), the Susquehanna Steam

Electric Station (Inspection Reports 50-387/90-200 and 50-388/90-200), and the

9104090124

' J

IN 91-29 April 15, 1991 Waterford Steam Electric Station (Inspection Report 50-382/90-23), the staff

found that, under certain conditions, the voltage available at the safety buses

would be inadequate to Operate safety-related loads and associated equipment.

These conditions could occur when the plan~t's electrical distribution systems

were being supplied from an offsite grid that had become degraded but that

continued to supply voltages that remained above the setpoints at which the

degraded grid relays would be activated.

At San Onofre, the numerous voltage drops throughout the system could cause the

voltage to 120 Vaciontactors to drop below the-voltage range for which these

contactors were certified as acceptable by their manufacturers.

To resolve

this problem the licensee has performed testing that established a lower

acceptable voltage range for this equipment.

At Susquehanna, the degraded grid relay setpoint'was'set at 84 percent on the

4160 Yac buses.

Th'i's setpoint could have allowed inadequate voltage to be

-delivered to numerous safety-related loads at both the 480 Vac and 120 Vac

levels. The licensee calculated that setpoints'of at least 93 percent would be

required to ensure adequate voTtage to all safety-related equipment. To

resolve this problem, the lice'isee has raised the setpoints of the degraded

grid relays and has initiated a modification to install 120 Vac regulating

transformers.

At the Waterford nuclear plant, the degraded grid relays were set at

87.5 percent'as sensed on the'4160 Vac buses. :Although this setting was found

to be marginally adequate-'for-equipment connected to the 4160 Vac buses, the

setting was too low to ensure that adequate v6ltage would'be maintained at the

480 Vac and 120 Vac levels. The licensee is 6e4aluating solutions to this

problem and has instituted a procedure- to manually'separate from the grid if

the voltage falls to unacceptable levels but remains above the relay setpoints.

The function of the degraded grid relays is to en'sure that adequate voltage is

available tooperate all Class lE loads at all distribution levels.

In order

to ensure-that all required' Class E 'loads will remain operable during degraded

voltage conditions, some licensees are currently'reanalyzing the basis for the

degraded grid relay setpoints. The new analyses consider all required Class 1E

loads and include the assumption that the voltage on the buses being sensed by

these relays can remain at a level just above the relay setpoints.

Inadequate Circuit Breaker Testing Procedures

During recent EDSFIs ahd previously on other NRC inspections, the staff identi- fied repetitive deficiencies in licensees' programs to test circuit breakers.

These deficiencies included inadequate procedures, inadequate test acceptance

criteria, inadequate test equipment, and inadequate control of testing. At the

Susquehanna plant (Inspection Reports 50-387/90-200 and 50-388/90-200), the

staff found that the licensee was testing dc molded case circuit breakers with

a procedure written for testing ac breakers. The licensee had not established

specific acceptance criteria for the dc breakers.

IN 91-29 April 15, 1991 At the Shearon Harris Nuclear Power Plant (Inspection Report 50-400/90-200),

the staff identified that the licensee was.testing molded case circuit breakers

against National Electrical Manufacturers Association (NEMA),acceptance crite- ria, which were less stringent than the manufacturer's time-current curves for

these breakers. In addition, the staff identified that the licensee was

testing 480 V air circuit breakers with test equipment that applied a test

signal (secondary injection) to the solid state trip units in the circuit

breakers.

Although this method adequately verified that the trip units func- tioned properly, it did not verify that the breaker's current transformer

functioned properly or that the wiring and connectors were adequate between the

current transformer and the solid state trip units. Other licensees have

performed testing by primary current injection or by individually checking each

component of the circuit breaker, including the wiring and connectors to

demonstrate that the circuit breaker functions properly.

Inadequate Determinations and Evaluations of Setpoints

Many of the findings identified during recent EDSFIs were related to inadequate

setpoint determinations. Useful guidance for determining setpoints is provided

by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear

Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC

staff has endorsed by Regulatory Guide 1.105 Revision 2 -

1986, "Instrument

Setpoints for Safety-Related Systems." This guidance applies both to process

instrumentation and, in part, to certain relays that perform a safety function.

Some licensees have operated equipment outside of acceptable limits because

they did not determine proper setpoints and did not evaluate and account for

instrument drift. Operating the equipment under these conditions could

compromise the safety functions of the equipment. The staff has identified

these circumstances primarily for those instruments in which the licensee has

determined the setpoints as opposed to those instruments for which the

setpoints were determined by the architect/engineer or the nuclear safety

system supplier. Those setpoints not contained in the plant technical specifi- cations were also more frequently found to be deficient. During recent EDSFIs, the staff identified deficiencies in setpoints for diesel day tank level

indicators, diesel air start compressor controllers and alarms, inverter low

voltage shutdown circuitry, degraded grid relays, and diesel overcurrent

relays.

In addition to identifying deficiencies in the setpoints themselves, the NRC

has determined that not all the licensees are typically verifying that the

magnitude of instrument drift that was assumed in the original setpoint calcu- lation coincides with the magnitude of drift observed in the plant. Some

licensees have corrected this deficiency by verifying the magnitude of instru- ment drift by trending, (comparing "as found" calibration data to previous "as

left" data). This is particularly important for the degraded grid relay

setpoints, which often require very tight calibration tolerance bands, and for

which very low drift values are often assumed.

v- IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, eirector

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices

i

Attachment 1

IN 91-29

April 15, 1991 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

91-28

91-27

89-90,

Supp. 1

91-26

91-25

91-24

91-23

Cracking in Feedwater

System Piping

Incorrect Rotation of

Positive Displacement Pump

Pressurizer Safety Valve

Lift Setpoint Shift

Potential Nonconservative

Errors in the Working Format

Hansen-Roach Cross-Section

Set Provided with The Keno

and Scale Codes

Commercial-Grade Structural

Framing Components Supplied

As Nuclear Safety-Related

Equipment

Recent Operating Experience

Involving Reactor Operation

Without A Licensed Reactor

Operator or Senior Reactor

Operator Present in the

Control Room

Accidental Radiation Over- exposures to Personnel Due to

Industrial Radiography Acces- sory Equipment Malfunctions

04/15/91

All holders of OLs or

CPs for pressurized

water reactors (PWRs).

04/10/91

All holders of OLs or

CPs for nuclear power

reactors.

04/10/91

All holders of OLs or

CPs for nuclear power

reactors.

04/02/91

All fuel cycle licensees

and other licensees, in- cluding all holders of

operating licenses for

nuclear power reactors, who use physics codes to

support criticality

safety in the use of

fissile material.

04/01/91

All holders of OLs or

CPs for nuclear power

reactors.

03/26/91

All holders of OLs or

CPs for nuclear power, test, and research re- actors, and all Part 55 licensed operators.

03/26/91

All Nuclear Regulatory

Commission (NRC) licens- ees authorized to use

sealed sources for indus- trial radiography.

OL = Operating License

CP = Construction Permit

IN 91-29 April 15, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

O6ginal agen& by

Charles E. Ross!

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment:

List of Recently Issued NRC Information Notices

  • SEE PREVIOUS

04/ fI9 OGC :DOEA: RR

PCWen

04/

/91

CONCURRENCES

  • C/OGCB:DOEA:NRR*RPB:ADM
  • C/SICB:DST:NRR

CHBerlinger

TechEd

SNewberry

04/08/91

03/20/91

03/18/91

  • RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRIS:NRR

JBJacobson:bt

EVImbro

WDLanning

02/08/91

02/08/91

02/19/91

  • C/SELB:DST:NRR

FRosa

03/18/91

  • D/DRIS:NRR

BKGrimes

02/27/91

  • - I

IN 91-XX

April xx, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996

List of Recently Issued NRC Information Notices

Attachment:

  • SEE PREVIOUS CONCURRENCES
  • C/SICB:DST:NRR

D/DOEA:NRR

C/OGCB:DO

T*RPB:Ad

SNewBerry

CERossi Y-

CHBerling rjw TechEd

04/ /91

04/8/91

03/20/91

03/18/91

,c

CB:DOEA:NRR *RSIB:DRIS:NRR *SC/RSIB:DRIS:NRR*C/RSIB:DRISNRR

4CvPvWen

JBJacobson:bt

EVImbro

WMLanning

04/cl/91

02/08/91

02/08/91

02/19/91

  • C/SELB:DST:NRR

FRosa

03/18/91

  • D/DRIS:NRR

BKGrimes

02/27/91

IN 91-XX

March xx, 1991 Inadequate Determinations and Evaluations of Setpoints

Many of the findings identified during recent EDSFIs related to inadequate

setpoint determinations. Useful guidance for determining setpoints is provided

by Instrument Society of America Standard 67.04-1982, "Setpoints for Nuclear

Safety-Related Instrumentation used in Nuclear Power Plants," which the NRC

staff has endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument

Setpoints for Safety-Related Systems." This guidance applies both to process

instrumentation and, in part, to certain relays that perform a safety function.

Licensees have operated equipment outside of acceptable limits because they did

not determine proper setpoints and did not evaluate and account for instrument

drifts. Operating the equipment under these conditions could compromise the

safety functions of the equipment. The staff has identified these circum- stances primarily for those instruments in which the licensee has determined

the setpoints as opposed to those instruments for which the setpoints were

determined by the architect/engineer or the nuclear safety system supplier.

Those setpoints not contained in the plant technical specifications were also

more frequently found to be deficient. During recent EDSFIs, the staff

identified deficiencies in setpoints for diesel day tank level indicators, diesel air start compressor controllers and alarms, inverter low voltage

shutdown circuitry, degraded grid relays, and diesel overcurrent relays.

In addition to identifying deficiencies in the setpoints themselves, the NRC

has determined that licensees are not typically verifying that the magnitude

of instrument drift that was assumed in the original setpoint calculation

coincides with the magnitude of drift observed in the plant.

Licensee can

verify the magnitude of instrument drift by trending, (comparing 'as found"

calibration data to previous 'as left" data). This is particularly important

for the degraded grid relay setpoints, which often require very tight calibra- tion tolerance bands, and for which very low drift values are often assumed.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment:

RPB:ADM

TechEd* imJa

03/20/91 P

RSIB:DRIS

JBdacobson*:t

02/08/91

List of Recently Issued NRC Information Notices

C:OGCB:UOEA

D:DOEA

  • See previous c

CHBerlinger

CERossi

1 03/l/91

03/ /91 oncurrence

bt

SC:RSIB:DRIS

EVImbro*

02/08/91 C:RSIB:DRIS

WDLanning*

02/19/91 D:DRIS

BKGrimes*

02/27/91 C:SELB:DST

FRosa*

03/18/91 C:SICB:DST

SNewberry*

03/18/91

-

IN 91-XX

January xx, 1991 Inadequate Setpoint Determinations and Evaluations

Many of the findings identified during recent EDSFIs were related to inadequate

setpoint determinations. In order to properly determine an appropriate

instrument setpoint, all associated inaccuracies and tolerances must be

accounted for. Useful guidance for determining setpoints is provided by ISA

67.04-1982, "Setpoints for Nuclear Safety-Related Instrumentation used in

Nuclear Power Plants' which has been endorsed by Regulatory Guide 1.105 Revision 2 - 1986, "Instrument Setpoints for Safety Related Systems". This

guidance is applicable not Just for instrumentation but is also applicable for

certain relays and other control oriented pieces of equipment.

The setpoint problem has been identified primarily with those instruments in

which the licensee has determined the setpoints as opposed to those setpoints

determined by the NSSS vendor. Those setpoints not contained in the plant

technical specifications are also likely to be suspect. During recent EDSFIs, deficiencies in setpoints related to diesel day tank level indicators, diesel

air start compressor controllers and alarms, invertor low voltage shutdown

circuitry, degraded grid relays, and diesel overcurrent relays have been

identified.

In addition to the deficiencies identified in the setpoints themselves, the NRC

has determined that licensees are not typically verifying that the magnitude of

setpoint drift that was assumed in the original setpoint calculation is indeed

correct. This verification can be performed by trending, i.e., by comparing

"as found" calibration data to previous "as left" data. This is particularly

important for the degraded grid setpoints where very tight calibration

tolerance bands are often required and where very low drift values are often

assumed. Failure to evaluate and account for instrument drifts has led to the

operation of equipment outside of acceptable limits which could compromise the

safety functions of the equipment.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment:

List of Recently Issued NRC Information Notices

  • See previous concurrence

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IN 91-XX

January xx, 1991 Inadequate Setpoint Determinations and Evaluations

Many of the findings identified during recent EDSFIs were related to inadequate

setpoint determinations. In order to properly determine an appropriate

instrument setpoint, all associated inaccuracies and tolerances must be

accounted for. Guidance for setpoint determinations is given in ANSI Standard

S67.04-1988, 'Setpoints for Nuclear Safety-Related Instrumentation." This

guidance is applicable not Just for instrumentation but is also applicable for

certain relays and other control oriented pieces of equipment.

The setpoint problem is most prevalent for those instruments in which the

licensee has determined the setpoints as opposed to those setpoints determined

by the NSSS vendor. Those setpoints not contained in the plant technical

specifications are also likely to be suspect. During recent EDSFIs, defi- ciencies in setpoints related to diesel day tank level indicators, diesel air

start compressor controllers and alarms, invertor low voltage shutdown

circuitry, degraded grid relays, and diesel overcurrent relays have been

identified.

In addition to the deficiencies identified in the setpoints themselves, the NRC

has determined that licensees are not typically verifying that the magnitude of

setpoint drift that was assumed in the original setpoint calculation is indeed

correct. This verification can be performed by trending, i.e., by comparing

"as found" calibration data to previous "as left" data. This is particularly

important for the degraded grid rely setpoints where very tight calibration

tolerance bands are often required and where very low drift values are often

assumed. Failure to evaluate and account for instrument drifts has led to the

operation of equipment outside of acceptable limits which could compromise the

safety functions of the equipment.

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contact:

Jeffrey B. Jacobson, NRR

(301) 492-0996 Attachment: List of Recently Issued NRC Information Notices

RPB:ADM

C:OGCB:DOEA

D:DOEA

TechEd

CHBerlinger

CERossi

02/ /91

02/ /91

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