Information Notice 1997-21, Availability of Alternate AC Power Source Designed for Station Blackout Event: Difference between revisions

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{{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY
{{#Wiki_filter:UNITED STATES


COMMISSION
NUCLEAR REGULATORY COMMISSION


===OFFICE OF NUCLEAR REACTOR REGULATION===
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001 April 18, 1997 NRC INFORMATION


NOTICE 97-21: AVAILABILITY
WASHINGTON, D.C. 20555-0001 April 18, 1997 NRC INFORMATION NOTICE 97-21:               AVAILABILITY OF ALTERNATE AC POWER


OF ALTERNATE
SOURCE DESIGNED FOR STATION BLACKOUT


AC POWER SOURCE DESIGNED FOR STATION BLACKOUT EVENT
EVENT


==Addressees==
==Addressees==
All holders of operating
All holders of operating licenses for nuclear power reactors.
 
licenses for nuclear power reactors.


==Purpose==
==Purpose==
The U.S. Nuclear Regulatory
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert
 
Commission (NRC) is issuing this information
 
notice to alert addressees
 
to potential
 
unavailability
 
of an alternate
 
ac (AAC) power source during a station blackout (SBO) event. It is expected that recipients
 
will review this information
 
for applicability
 
to their facilities
 
and consider actions, as appropriate, to avoid similar problems.However, suggestions
 
contained
 
in this information
 
notice are not NRC requirements;
therefore, no specific action or written response is required.Description
 
of Circumstances
 
On March 11-29, and May 13-22, 1996, a special inspection
 
team from the NRC assessed the engineering
 
and licensing


activities
addressees to potential unavailability of an alternate ac (AAC) power source during a station


at Millstone
blackout (SBO) event. It is expected that recipients will review this information for


Nuclear Power Station. During a review of the Millstone
applicability to their facilities and consider actions, as appropriate, to avoid similar problems.


Unit 3 SBO systems, the team identified
However, suggestions contained in this information notice are not NRC requirements;
therefore, no specific action or written response is required.


a concern about the design of the AAC power source, the SBO diesel generator (DG), and its dedicated
==Description of Circumstances==
On March 11-29, and May 13-22, 1996, a special inspection team from the NRC assessed


battery. The AAC power source may not be available
the engineering and licensing activities at Millstone Nuclear Power Station. During a review


if an SBO occurs as a result of a loss of onsite power, i.e., the EDGs, following
of the Millstone Unit 3 SBO systems, the team identified a concern about the design of the


1 hour of loss of offsite (preferred)
AAC power source, the SBO diesel generator (DG), and its dedicated battery. The AAC
power (LOOP). The AAC power source at Millstone


Unit 3 is controlled
power source may not be available if an SBO occurs as a result of a loss of onsite power, i.e., the EDGs, following 1 hour of loss of offsite (preferred) power (LOOP). The AAC power


and monitored
source at Millstone Unit 3 is controlled and monitored by a computer. The AAC power


by a computer.
system includes two batteries, one 48-volt battery for the computer and one 125-volt battery


The AAC power system includes two batteries, one 48-volt battery for the computer and one 125-volt battery for DG field flashing, oil pump, and breaker control power. The battery chargers for these batteries
for DG field flashing, oil pump, and breaker control power. The battery chargers for these


are fed from offsite power when the AAC power is not operating.
batteries are fed from offsite power when the AAC power is not operating. If offsite power is


If offsite power is lost for a significant
lost for a significant period, these batteries will be depleted as a result of the connected loads


period, these batteries
(the computer for the 48-volt battery and the EDG oil pump for the 125-volt battery). If AAC


will be depleted as a result of the connected
power is needed more than 1 hour after the loss of offsite power, the batteries will be so


loads (the computer for the 48-volt battery and the EDG oil pump for the 125-volt battery).
depleted that the SBO DG cannot be started and therefore, will not be available if EDGs are


If AAC power is needed more than 1 hour after the loss of offsite power, the batteries
lost.


will be so depleted that the SBO DG cannot be started and therefore, will not be available
On March 7, 1997, during a refueling outage at Pilgrim Unit 1 a main transformer failure


if EDGs are lost.On March 7, 1997, during a refueling
resulted in both safety buses losing power. One safety bus was energized from the


outage at Pilgrim Unit 1 a main transformer
shutdown transformer and the other from EDG "B." Approximately 6 hours into the event, operators attempted to start the SBO DG, but failed. The SBO-DG failed to start because the


failure resulted in both safety buses losing power. One safety bus was energized
PDRA X4-E 06rICE 7T-Ozf T7vq18
                                                                  1INlpiglpig PIlllstl~lll


from the shutdown transformer
IN 97-21 April 18, 1997 DG support systems, particularly the lubricating oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite


and the other from EDG "B." Approximately
power. This extended loss of auxiliary power caused the oil temperature to drop and that


6 hours into the event, operators
resulted in oil pressure below the minimum pressure required for DG operation.
 
attempted
 
to start the SBO DG, but failed. The SBO-DG failed to start because the PDRA X4-E 06rICE 7T-Ozf T7vq18 1INlpiglpig
 
PIlllstl~lll
 
IN 97-21 April 18, 1997 DG support systems, particularly
 
the lubricating
 
oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite power. This extended loss of auxiliary
 
power caused the oil temperature
 
to drop and that resulted in oil pressure below the minimum pressure required for DG operation.


Discussion
Discussion


The Millstone
The Millstone licensee reviewed the design and operation of the MC power source at


licensee reviewed the design and operation
Millstone Unit 3 and determined that the MC power source required modification to assure


of the MC power source at Millstone
availability of the SBO DG for no less than 8 hours (the probable time needed to restore


Unit 3 and determined
offsite power) following a postulated LOOP event.


that the MC power source required modification
The Pilgrim licensee discovered that the SBO DC was susceptible to a failure to start as a


to assure availability
result of low oil temperature if power was lost to the lubricating oil keep-warm system for an


of the SBO DG for no less than 8 hours (the probable time needed to restore offsite power) following
extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes, or modifications to SBO DG start logic.


a postulated
The SBO DG capability to start on demand depends on the availability of the necessary


LOOP event.The Pilgrim licensee discovered
support systems to fulfill their required function. The SBO DG support systems may require


that the SBO DC was susceptible
varying combinations of dc or ac power for varying periods to maintain operational readiness.


to a failure to start as a result of low oil temperature
Prompt operator actions to conserve battery capacity, support system power supply


if power was lost to the lubricating
modifications, use of special procedures, or start logic modifications may be necessary to


oil keep-warm
preserve the operational readiness of the SBO DG under challenging environmental


system for an extended period. The licensee is considering
conditions. The staff is evaluating these events and the consequential need for additional


enhanced monitoring
generic communications.
 
of SBO DG auxiliaries, procedural
 
changes, or modifications
 
to SBO DG start logic.The SBO DG capability
 
to start on demand depends on the availability
 
of the necessary support systems to fulfill their required function.
 
The SBO DG support systems may require varying combinations
 
of dc or ac power for varying periods to maintain operational
 
readiness.


Prompt operator actions to conserve battery capacity, support system power supply modifications, use of special procedures, or start logic modifications
This information notice requires no specific action or written response. If you have any


may be necessary
questions about the .nformation in this notice, please contact one of the technical contacts


to preserve the operational
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.


readiness
Thomas T. Martin, Director


of the SBO DG under challenging
Division of Reactor Program Management


environmental
Office of Nuclear Reactor Regulation


conditions.
Technical contacts:      A. Pal, NRR                                David Skeen


The staff is evaluating
(301) 415-2760                              (301) 415-1174 E-mail: anpenrc.gov                        E-mail: dlsenrc.gov


these events and the consequential
Thomas Koshy


need for additional
(301) 415-1176 E-mail: txkenrc.gov


generic communications.
Attachment: List of Recently Issued NRC Information Notices


This information
4+,q¢ Mivr                -QfeLD A        )Ct


notice requires no specific action or written response.
<-IJ


If you have any questions
Attachment 1 IN 97-21 April 18, 1997 LIST OF RECENTLY ISSUED


about the .nformation
NRC INFORMATION NOTICES


in this notice, please contact one of the technical
Information                                      Date of


contacts listed below or the appropriate
Notice No.            Subject                    Issuance    Issued to


Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, Director Division of Reactor Program Management
97-20          Identification of               04/18'97    All holders of OLs


===Office of Nuclear Reactor Regulation===
Certain Uranium                              for nuclear power
Technical


contacts:
Hexafluoride Cylinders
A. Pal, NRR David Skeen (301) 415-2760 (301) 415-1174 E-mail: anpenrc.gov


E-mail: dlsenrc.gov
that do not comply


Thomas Koshy (301) 415-1176 E-mail: txkenrc.gov
with ANSI N14.1 Fabrication


Attachment:
Standards
List of Recently Issued NRC Information


Notices 4+,q&#xa2; Mivr -QfeLD A )Ct
97-19          Safaty Injection                04/1 8,'/7  All holders of OLs


<-IJ Attachment
System Weld Flaw at                          or CPs for nuclear


1 IN 97-21 April 18, 1997 LIST OF RECENTLY ISSUED NRC INFORMATION
Sequoyah Nuclear                              power reactors


NOTICES Information
Power Plant, Unit 2
94-14,          Failure to Implement            04/14/97    All holders of OLs


Date of Notice No. Subject Issuance Issued to 97-20 97-19 94-14, Supp. 1 97-18 97-17 Identification
Supp. 1         Requirements for                            or CPs for nuclear


of Certain Uranium Hexafluoride
Biennial Medical                            power and non-power


Cylinders that do not comply with ANSI N14.1 Fabrication
Examinations and                              reactors and all


Standards Safaty Injection System Weld Flaw at Sequoyah Nuclear Power Plant, Unit 2 Failure to Implement Requirements
Notification to the                          licensed reactor


for Biennial Medical Examinations
NRC of Changes in                            operators and senior


and Notification
Licensed Operator                            reactor operators


to the NRC of Changes in Licensed Operator Medical Conditions
Medical Conditions


===Problems Identified===
97-18          Problems Identified               04/14/97    All holders of OLs, During Maintenance                           CPs, and decommissioning- Rule Baseline Inspections                    stage licenses for
During Maintenance


===Rule Baseline Inspections===
nuclear power reactors
Cracking of Vertical Welds in the Core Shroud and Degraded Repair 04/18'97 04/1 8,'/7 04/14/97 04/14/97 04/04/97 All holders of OLs for nuclear power All holders of OLs or CPs for nuclear power reactors All holders of OLs or CPs for nuclear power and non-power reactors and all licensed reactor operators


and senior reactor operators All holders of OLs, CPs, and decommissioning- stage licenses for nuclear power reactors All holders of OLs or CPs for boiling-water reactors OL = Operating
97-17          Cracking of Vertical              04/04/97    All holders of OLs


License CP = Construction
Welds in the Core                            or CPs for boiling- Shroud and Degraded                          water reactors


Permit
Repair


IN 97-21 April 18,1997 DG support systems, particularly
OL = Operating License


the lubricating
CP = Construction Permit


oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite power. This extended loss of auxiliary
IN 97-21 April 18,1997 DG support systems, particularly the lubricating oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite


power caused the oil temperature
power. This extended loss of auxiliary power caused the oil temperature to drop and that


to drop and that resulted in oil pressure below the minimum pressure required for DG operation.
resulted in oil pressure below the minimum pressure required for DG operation.


Discussion
Discussion


The Millstone
The Millstone licensee reviewed the design and operation of the MC power source at
 
licensee reviewed the design and operation
 
of the MC power source at Millstone
 
Unit 3 and determined
 
that the AAC power source required modification
 
to assure availability
 
of the SBO DG for no less than 8 hours (the probable time needed to restore offsite power) following
 
a postulated
 
LOOP event.The Pilgrim licensee discovered
 
that the SBO DG was susceptible
 
to a failure to start as a result of low oil temperature
 
if power was lost to the lubricating
 
oil keep-warm
 
system for an extended period. The licensee is considering
 
enhanced monitoring
 
of SBO DG auxiliaries, procedural
 
changes, or modifications


to SBO DG start logic.The SBO DG capability
Millstone Unit 3 and determined that the AAC power source required modification to assure


to start on demand depends on the availability
availability of the SBO DG for no less than 8 hours (the probable time needed to restore


of the necessary support systems to fulfill their required function.
offsite power) following a postulated LOOP event.


The SBO DG support systems may require varying combinations
The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a


of dc or ac power for varying periods to maintain operational
result of low oil temperature if power was lost to the lubricating oil keep-warm system for an


readiness.
extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes, or modifications to SBO DG start logic.


Prompt operator actions to conserve battery capacity, support system power supply modifications, use of special procedures, or start logic modifications
The SBO DG capability to start on demand depends on the availability of the necessary


may be necessary
support systems to fulfill their required function. The SBO DG support systems may require


to preserve the operational
varying combinations of dc or ac power for varying periods to maintain operational readiness.


readiness
Prompt operator actions to conserve battery capacity, support system power supply


of the SBO DG under challenging
modifications, use of special procedures, or start logic modifications may be necessary to


environmental
preserve the operational readiness of the SBO DG under challenging environmental


conditions.
conditions. The staff is evaluating these events and the consequential need for additional
 
The staff is evaluating
 
these events and the consequential
 
need for additional


generic communications.
generic communications.


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


notice requires no specific action or written response.
questions about the information in this notice, please contact one of the technical contacts


If you have any questions
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.


about the information
Thomas T. Martin, Director


in this notice, please contact one of the technical
Division of Reactor Program Management


contacts listed below or the appropriate
Office of Nuclear Reactor Regulation


Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, Director Division of Reactor Program Management
Technical contacts:      A. Pal, NRR                                          David Skeen


===Office of Nuclear Reactor Regulation===
(301) 415-2760                                        (301) 415-1174 E-mail: anp@nrc.gov                                  E-mail: dls@nrc.gov
Technical


contacts:
Thomas Koshy
A. Pal, NRR David Skeen (301) 415-2760 (301) 415-1174 E-mail: anp@nrc.gov


E-mail: dls@nrc.gov
(301) 415-1176 E-mail: txk@nrc.gov


Thomas Koshy (301) 415-1176 E-mail: txk@nrc.gov
Attachment: List of Recently Issued NRC Information Notices


Attachment:  
DOCUMENT NAME: S:\DRPMSEC\97-21.lN                          *SEE PREVIOUS CONCURRENCES
List of Recently Issued NRC Information


Notices DOCUMENT NAME: S:\DRPMSEC\97-21.lN
To receive a copy of Us document, Indicate In the box: V' a Copy without enclosures "E" c Copy with enlosures "N" No copy


*SEE PREVIOUS CONCURRENCES
OFFICE        TECH


To receive a copy of Us document, Indicate In the box: V' a Copy without enclosures "E" c Copy with enlosures "N" No copy OFFICE TECH
==CONTACT==
S              C:EELB                  CPECB                    D:DRPMl


==CONTACT==
NAME         APa1*                     JCalvo*                 AChaffee*                 T~artin
S C:EELB CPECB D:DRPMl NAME APa1* JCalvo* AChaffee*  
T~artin DSkeen*_DATE 04/07/97 04/07/97 04/11/97 04/ 97 OFFICIAL RECORD COPY


IN 97 -xx April xx, 1997 DG support systems, particularly
DSkeen*_
DATE          04/07/97                   04/07/97                04/11/97                  04/      97 OFFICIAL RECORD COPY


the lubricating
IN 97 -xx


oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite power. This extended loss of auxiliary
April xx, 1997 DG support systems, particularly the lubricating oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite


power caused the oil temperature
power. This extended loss of auxiliary power caused the oil temperature to drop and that


to drop and that resulted in oil pressure below the minimum pressure required for DG operation.
resulted in oil pressure below the minimum pressure required for DG operation.


Discussion
Discussion


The Millstone
The Millstone licensee reviewed the design and operation of the MC power source at
 
licensee reviewed the design and operation
 
of the MC power source at Millstone


Unit 3 and determined
Millstone Unit 3 and determined that the AAC power source required modification to assure


that the AAC power source required modification
availability of the SBO DG for no less than 8 hours (the probable time needed to restore


to assure availability
offsite power) following a postulated LOOP event.


of the SBO DG for no less than 8 hours (the probable time needed to restore offsite power) following
The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a


a postulated
result of low oil temperature if power was lost to the lubricating oil keep-warm system for an


LOOP event.The Pilgrim licensee discovered
extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes, or modifications to SBO DG start logic.


that the SBO DG was susceptible
The SBO DG capability to start on demand depends on the availability of the necessary


to a failure to start as a result of low oil temperature
support systems to fulfill their required function. The SBO DG support systems may require


if power was lost to the lubricating
varying combinations of dc or ac power for varying periods to maintain operational readiness.


oil keep-warm
Prompt operator actions to conserve battery capacity, support system power supply


system for an extended period. The licensee is considering
modifications, use of special procedures, or start logic modifications may be necessary to- preserve the operational readiness of the SBO DG under challenging environmental


enhanced monitoring
conditions. The staff is evaluating these events and the consequential need for additional
 
of SBO DG auxiliaries, procedural
 
changes, or modifications
 
to SBO DG start logic.The SBO DG capability
 
to start on demand depends on the availability
 
of the necessary support systems to fulfill their required function.
 
The SBO DG support systems may require varying combinations
 
of dc or ac power for varying periods to maintain operational
 
readiness.
 
Prompt operator actions to conserve battery capacity, support system power supply modifications, use of special procedures, or start logic modifications
 
may be necessary
 
to-preserve the operational
 
readiness
 
of the SBO DG under challenging
 
environmental
 
conditions.
 
The staff is evaluating
 
these events and the consequential
 
need for additional


generic communications.
generic communications.


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


notice requires no specific action or written response.
questions about the information in this notice, please contact one of the technical contacts


If you have any questions
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.


about the information
Thomas T. Martin, Director


in this notice, please contact one of the technical
Division of Reactor Program Management


contacts listed below or the appropriate
Office of Nuclear Reactor Regulation


Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, Director Division of Reactor Program Management
Technical contacts:        A. Pal, NRR                                          David Skeen


===Office of Nuclear Reactor Regulation===
(301) 415-2760                                      (301) 415-1174 E-mail: anp@nrc.gov                                  E-mail: dls@nrc.gov
Technical


contacts:
Thomas Koshy
A. Pal, NRR David Skeen (301) 415-2760 (301) 415-1174 E-mail: anp@nrc.gov


E-mail: dls@nrc.gov
(301) 415-1176 E-mail: btk@nrc.gov


Thomas Koshy (301) 415-1176 E-mail: btk@nrc.gov
Attachment: List of Recently Issued NRC Information Notices


Attachment:  
DOCUMENT NAME: G:%TXKXSBO.3                                  *SEE PREVIOUS CONCURRENCES
List of Recently Issued NRC Information


Notices DOCUMENT NAME: G:%TXKXSBO.3
To receive a copy of this document, Indicate In the box: "C' = Copy wftiout enclosures "E - Copy with enclosures "N" No copy
*SEE PREVIOUS CONCURRENCES


To receive a copy of this document, Indicate In the box: "C' = Copy wftiout enclosures "E -Copy with enclosures "N" No copy OFFICE TECH
OFFICE       TECH


==CONTACT==
==CONTACT==
S I IC:EELB C I D: DRPM NAME APal* JCalvo* AChaffee*
S                   I       IC:EELB     C             I         D: DRPM
TMartin TKoshy DSkeen*DATE 04/07/97 04/07/97 04/11/97 04/ /97 OFFICIALTRECOR


I C/OP 4 fX' q11V?7
NAME          APal*                       JCalvo*                AChaffee*                TMartin
* lN 97 -xx April xx, 1997 safety related power supply and had been out for an extended period during the loss of offsite power. This extended loss of auxiliary


power caused the oil temperature
TKoshy


to drop and that resulted in oil pressure below the minimum pressure required for DG operation.
DSkeen*
DATE          04/07/97                    04/07/97                04/11/97                04/    /97 OFFICIALTRECOR C/OPI


Discussion
4 fX' q11V?7


The Millstone
*                                                              lN 97 -xx


licensee reviewed the design and operation
April xx, 1997 safety related power supply and had been out for an extended period during the loss of


of the AAC power source at Millstone
offsite power. This extended loss of auxiliary power caused the oil temperature to drop and


Unit 3 and determined
that resulted in oil pressure below the minimum pressure required for DG operation.


that the AAC power source required modification
Discussion
 
to assure availability
 
of the SBO DG for no less than 8 hours (the probable time needed to restore offsite power) following
 
a postulated
 
LOOP event.The Pilgrim licensee discovered
 
that the SBO DG was susceptible
 
to a failure to start as a result of low oil temperature
 
if power was lost to the lubricating


oil keep-warm
The Millstone licensee reviewed the design and operation of the AAC power source at


system for an extended period. The licensee is considering
Millstone Unit 3 and determined that the AAC power source required modification to assure


enhanced monitoring
availability of the SBO DG for no less than 8 hours (the probable time needed to restore


of SBO DG auxiliaries, procedural
offsite power) following a postulated LOOP event.


changes or modifications
The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a


to SBO DG start logic.The SBO DG capability
result of low oil temperature if power was lost to the lubricating oil keep-warm system for an


to start on demand depends on the availability
extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes or modifications to SBO DG start logic.


of the necessary support systems to fulfill their required function.
The SBO DG capability to start on demand depends on the availability of the necessary


The SBO DG support systems may require varying combinations
support systems to fulfill their required function. The SBO DG support systems may require


of dc or ac power for varying periods to maintain operational
varying combinations of dc or ac power for varying periods to maintain operational readiness.


readiness.
Prompt operator actions to conserve battery capacity, support system power supply


Prompt operator actions to conserve battery capacity, support system power supply modifications, use of special procedures, or start logic modifications
modifications, use of special procedures, or start logic modifications may be necessary to


may be necessary
preserve the operational readiness of the SBO DG under challenging environmental


to preserve the operational
conditions. The staff is evaluating these events and the consequential need for additional
 
readiness
 
of the SBO DG under challenging
 
environmental
 
conditions.
 
The staff is evaluating
 
these events and the consequential
 
need for additional


generic communications.
generic communications.


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


notice requires no specific action or written response.
questions about the information in this notice, please contact one of the technical contacts


If you have any questions
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.


about the information
Thomas T. Martin, Director


in this notice, please contact one of the technical
Division of Reactor Program Management


contacts listed below or the appropriate
Office of Nuclear Reactor Regulation


Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, Director Division of Reactor Program Management
Technical Contacts: A. Pal, NRR                             Thomas Koshy David Skeen


===Office of Nuclear Reactor Regulation===
(301) 415-2760                    (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV TXK@NRC.GOV DLS@NRC.GOV
Technical


Contacts:  
Attachment: List of Recently Issued NRC Information Notices
A. Pal, NRR Thomas Koshy David Skeen (301) 415-2760 (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV


TXK@NRC.GOV
DOCUMENT NAME: G:%TXKMSBO.3 To receive a copy of this document, Indicate In the box:  "CT a Copy without enclosures "'Fn Copy with enclosures "N'u No copy


DLS@NRC.GOV
OFFICE       TECH
 
Attachment:
List of Recently Issued NRC Information
 
Notices DOCUMENT NAME: G:%TXKMSBO.3 To receive a copy of this document, Indicate In the box: "CT a Copy without enclosures
 
"'F n Copy with enclosures "N' u No copy OFFICE TECH


==CONTACT==
==CONTACT==
S I :EELB T C:PECB lm DI IPIM NAME APal* JCalvo* AChaffee TMartin TKoshy DSkeen*DATE 04/07/97 04/07/97 04,1/97 104/ /97 OFFICIAL RECORD COPY
S I               :EELB       T         C:PECB               lm DI               IPIM


*. I"7 -xx March xx, 1997 safety related power supply and had been out for an extended period during the loss of offsite power. This extended loss of auxiliary
NAME          APal*                       JCalvo*                  AChaffee                  TMartin


power caused the oil temperature
TKoshy


to drop and that resulted in oil pressure below the minimum pressure required for DG operation.
DSkeen*
DATE          04/07/97                    04/07/97                04,1/97                104/    /97 OFFICIAL RECORD COPY


Discussion
*.                                                                            I"7 -xx


The Millstone
March xx, 1997 safety related power supply and had been out for an extended period during the loss of


licensee reviewed the design and operation
offsite power. This extended loss of auxiliary power caused the oil temperature to drop


of the AAC power source at Millstone
and that resulted in oil pressure below the minimum pressure required for DG operation.


Unit 3 and determined
Discussion


that the AAC power source required modification
The Millstone licensee reviewed the design and operation of the AAC power source at


to assure availability
Millstone Unit 3 and determined that the AAC power source required modification to


of the SBO DG for no less than 8 hours (the probable time needed to restore offsite power) following
assure availability of the SBO DG for no less than 8 hours (the probable time needed to


a postulated
restore offsite power) following a postulated LOOP event.


LOOP event.The Pilgrim licensee discovered
The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a


that the SBO DG was susceptible
result of low oil temperature if power was lost to the lubricating oil keep-warm system for


to a failure to start as a result of low oil temperature
an extended period. The licensee is considering enhanced monitoring of SBO DG


if power was lost to the lubricating
auxiliaries, procedural changes or modifications to SBO DG start logic.


oil keep-warm
The SBO DG capability to start on demand depends on the availability of the necessary


system for an extended period. The licensee is considering
support systems to fulfill their required function. The SBO DG support systems may


enhanced monitoring
require varying combinations of dc or ac power for varying periods to maintain operational


of SBO DG auxiliaries, procedural
readiness. Prompt operator actions to conserve battery capacity, support system power


changes or modifications
supply modifications, use of special procedures, or start logic modifications may be


to SBO DG start logic.The SBO DG capability
necessary to preserve the operational readiness of the SBO DG under challenging


to start on demand depends on the availability
environmental conditions. The staff is evaluating these events and the consequential need


of the necessary support systems to fulfill their required function.
for additional generic communications.


The SBO DG support systems may require varying combinations
This information notice requires no specific action or written response. If you have any


of dc or ac power for varying periods to maintain operational
questions about the information in this notice, please contact one of the technical contacts


readiness.
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project


Prompt operator actions to conserve battery capacity, support system power supply modifications, use of special procedures, or start logic modifications
manager.


may be necessary
Thomas T. Martin, Director


to preserve the operational
Division of Reactor Program Management


readiness
Office of Nuclear Reactor Regulation


of the SBO DG under challenging
Technical Contacts: A. Pal, NRR                          Thomas Koshy David Skeen


environmental
(301) 415-2760              (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV TXK@NRC.GOV DLS@NRC.GOV


conditions.
Attachment: List of Recently Issued NRC Information Notices


The staff is evaluating
DOCUMENT NAME: G:\TXK\SBO.3 To receive a copy of this document. Indicate Inthe box: Ca- Copy without enclosures E - Copy with enclosures EN" = No copy


these events and the consequential
IOFFICE        TECH


need for additional
==CONTACT==
 
S                C:EELB              C:PECB                  D:DRPM
generic communications.


This information
NAME          APa1*                        JCalvo*              AChaffee                TMartin


notice requires no specific action or written response.
TKoshy A


If you have any questions
DSkeen*
DATE          1046997                /97    04/      04/ /97                          104/ /97 OFFICIAL RECORD WPY7


about the information
I 1W7-xx


in this notice, please contact one of the technical
March xx, 1997 safety related power supply and had been out for an extended period during the loss of


contacts listed below or the appropriate
offsite power. This extended loss of auxiliary power caused the oil temperature to drop


Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, Director Division of Reactor Program Management
below the minimum temperature required for DG operation.
 
===Office of Nuclear Reactor Regulation===
Technical
 
Contacts:
A. Pal, NRR Thomas Koshy David Skeen (301) 415-2760 (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV
 
TXK@NRC.GOV
 
DLS@NRC.GOV
 
Attachment:
List of Recently Issued NRC Information
 
Notices DOCUMENT NAME: G:\TXK\SBO.3 To receive a copy of this document.
 
Indicate In the box: Ca- Copy without enclosures
 
E -Copy with enclosures
 
EN" = No copy IOFFICE TECH
 
==CONTACT==
S C:EELB C:PECB D:DRPM NAME APa1* JCalvo* AChaffee TMartin TKoshy A DSkeen*DATE 1046997 04/ /97 04/ /97 104/ /97 OFFICIAL RECORD WPY7 I 1W7-xx March xx, 1997 safety related power supply and had been out for an extended period during the loss of offsite power. This extended loss of auxiliary
 
power caused the oil temperature
 
to drop below the minimum temperature
 
required for DG operation.


Discussion
Discussion


The Millstone
The Millstone licensee reviewed the design and operation of the AAC power source at


licensee reviewed the design and operation
Millstone Unit 3 and determined that the AAC power source required modification to


of the AAC power source at Millstone
assure availability of the SBO DG for no less than 8 hours (the probable time needed to


Unit 3 and determined
restore offsite power) following a postulated LOOP event.


that the AAC power source required modification
The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a


to assure availability
result of low oil temperature if power was lost to the lubricating oil keep-warm system for


of the SBO DG for no less than 8 hours (the probable time needed to restore offsite power) following
an extended period. The licensee is considering enhanced monitoring of SBO DG


a postulated
auxiliaries, procedural changes or modifications to SBO DG start logic.


LOOP event.The Pilgrim licensee discovered
The SBO DG capability to start on demand depends on the availability of the necessary


that the SBO DG was susceptible
support systems to fulfill their required function. The SBO DG support systems may


to a failure to start as a result of low oil temperature
require varying combinations of dc or ac power for varying periods to maintain operational


if power was lost to the lubricating
readiness. Prompt operator actions to conserve battery capacity, support system power


oil keep-warm
supply modifications, use of special procedures, or start logic modifications may be


system for an extended period. The licensee is considering
necessary to preserve the operational readiness of the SBO DG under challenging


enhanced monitoring
environmental conditions. The staff is evaluating these events and the consequential need


of SBO DG auxiliaries, procedural
for additional generic communications.


changes or modifications
This information notice requires no specific action or written response. If you have any


to SBO DG start logic.The SBO DG capability
questions about the information in this notice, please contact one of the technical contacts


to start on demand depends on the availability
listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project


of the necessary support systems to fulfill their required function.
manager.


The SBO DG support systems may require varying combinations
Thomas T. Martin, Director


of dc or ac power for varying periods to maintain operational
Division of Reactor Program Management


readiness.
Office of Nuclear Reactor Regulation


Prompt operator actions to conserve battery capacity, support system power supply modifications, use of special procedures, or start logic modifications
Technical Contacts: A. Pal, NRR                              Thomas Koshy David Skeen


may be necessary
(301) 415-2760                  (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV TXK@NRC.GOV DLS@NRC.GOV


to preserve the operational
Attachment: List of Recently Issued NRC Information Notices


readiness
DOCUMENT NAME: G:\TXK\SBO.3 To receive a copy of this document, Indicate in the box: 'C' - Copy without enclosures 'E" - Copy with enclosures  N - No copy


of the SBO DG under challenging
OFFICE        TECH


environmental
==CONTACT==
 
S I                IC:EELB      TI      C:PECB            I      ID:DRPM            I
conditions.
 
The staff is evaluating


these events and the consequential
NAME          APa1*                          JCalvo*                AChaffee                  TMartin


need for additional
7Koshy


generic communications.
DSkeen*_
                          oats


This information
DATE          04/? /97                       04/     /97           04/ /97                   04/     /97 OFFICIAL RECORD COPY}}
 
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.Thomas T. Martin, Director Division of Reactor Program Management
 
===Office of Nuclear Reactor Regulation===
Technical
 
Contacts:
A. Pal, NRR Thomas Koshy David Skeen (301) 415-2760 (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV
 
TXK@NRC.GOV
 
DLS@NRC.GOV
 
Attachment:
List of Recently Issued NRC Information
 
Notices DOCUMENT NAME: G:\TXK\SBO.3 To receive a copy of this document, Indicate in the box: 'C' -Copy without enclosures
 
'E" -Copy with enclosures
 
N -No copy OFFICE TECH
 
==CONTACT==
S I IC:EELB TI C:PECB I ID:DRPM I NAME APa1* JCalvo* AChaffee TMartin 7Koshy oats DSkeen*_DATE 04/? /97 04/ /97 04/ /97 04/ /97 OFFICIAL RECORD COPY}}


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

Revision as of 03:43, 24 November 2019

Availability of Alternate AC Power Source Designed for Station Blackout Event
ML031050325
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  Entergy icon.png
Issue date: 04/18/1997
From: Martin T
Office of Nuclear Reactor Regulation
To:
References
IN-97-021, NUDOCS 9704180103
Download: ML031050325 (8)
v • d • e


UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 April 18, 1997 NRC INFORMATION NOTICE 97-21: AVAILABILITY OF ALTERNATE AC POWER

SOURCE DESIGNED FOR STATION BLACKOUT

EVENT

Addressees

All holders of operating licenses for nuclear power reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert

addressees to potential unavailability of an alternate ac (AAC) power source during a station

blackout (SBO) event. It is expected that recipients will review this information for

applicability to their facilities and consider actions, as appropriate, to avoid similar problems.

However, suggestions contained in this information notice are not NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

On March 11-29, and May 13-22, 1996, a special inspection team from the NRC assessed

the engineering and licensing activities at Millstone Nuclear Power Station. During a review

of the Millstone Unit 3 SBO systems, the team identified a concern about the design of the

AAC power source, the SBO diesel generator (DG), and its dedicated battery. The AAC

power source may not be available if an SBO occurs as a result of a loss of onsite power, i.e., the EDGs, following 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of loss of offsite (preferred) power (LOOP). The AAC power

source at Millstone Unit 3 is controlled and monitored by a computer. The AAC power

system includes two batteries, one 48-volt battery for the computer and one 125-volt battery

for DG field flashing, oil pump, and breaker control power. The battery chargers for these

batteries are fed from offsite power when the AAC power is not operating. If offsite power is

lost for a significant period, these batteries will be depleted as a result of the connected loads

(the computer for the 48-volt battery and the EDG oil pump for the 125-volt battery). If AAC

power is needed more than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> after the loss of offsite power, the batteries will be so

depleted that the SBO DG cannot be started and therefore, will not be available if EDGs are

lost.

On March 7, 1997, during a refueling outage at Pilgrim Unit 1 a main transformer failure

resulted in both safety buses losing power. One safety bus was energized from the

shutdown transformer and the other from EDG "B." Approximately 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> into the event, operators attempted to start the SBO DG, but failed. The SBO-DG failed to start because the

PDRA X4-E 06rICE 7T-Ozf T7vq18

1INlpiglpig PIlllstl~lll

IN 97-21 April 18, 1997 DG support systems, particularly the lubricating oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite

power. This extended loss of auxiliary power caused the oil temperature to drop and that

resulted in oil pressure below the minimum pressure required for DG operation.

Discussion

The Millstone licensee reviewed the design and operation of the MC power source at

Millstone Unit 3 and determined that the MC power source required modification to assure

availability of the SBO DG for no less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (the probable time needed to restore

offsite power) following a postulated LOOP event.

The Pilgrim licensee discovered that the SBO DC was susceptible to a failure to start as a

result of low oil temperature if power was lost to the lubricating oil keep-warm system for an

extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes, or modifications to SBO DG start logic.

The SBO DG capability to start on demand depends on the availability of the necessary

support systems to fulfill their required function. The SBO DG support systems may require

varying combinations of dc or ac power for varying periods to maintain operational readiness.

Prompt operator actions to conserve battery capacity, support system power supply

modifications, use of special procedures, or start logic modifications may be necessary to

preserve the operational readiness of the SBO DG under challenging environmental

conditions. The staff is evaluating these events and the consequential need for additional

generic communications.

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

questions about the .nformation in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: A. Pal, NRR David Skeen

(301) 415-2760 (301) 415-1174 E-mail: anpenrc.gov E-mail: dlsenrc.gov

Thomas Koshy

(301) 415-1176 E-mail: txkenrc.gov

Attachment: List of Recently Issued NRC Information Notices

4+,q¢ Mivr -QfeLD A )Ct

<-IJ

Attachment 1 IN 97-21 April 18, 1997 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

97-20 Identification of 04/18'97 All holders of OLs

Certain Uranium for nuclear power

Hexafluoride Cylinders

that do not comply

with ANSI N14.1 Fabrication

Standards

97-19 Safaty Injection 04/1 8,'/7 All holders of OLs

System Weld Flaw at or CPs for nuclear

Sequoyah Nuclear power reactors

Power Plant, Unit 2

94-14, Failure to Implement 04/14/97 All holders of OLs

Supp. 1 Requirements for or CPs for nuclear

Biennial Medical power and non-power

Examinations and reactors and all

Notification to the licensed reactor

NRC of Changes in operators and senior

Licensed Operator reactor operators

Medical Conditions

97-18 Problems Identified 04/14/97 All holders of OLs, During Maintenance CPs, and decommissioning- Rule Baseline Inspections stage licenses for

nuclear power reactors

97-17 Cracking of Vertical 04/04/97 All holders of OLs

Welds in the Core or CPs for boiling- Shroud and Degraded water reactors

Repair

OL = Operating License

CP = Construction Permit

IN 97-21 April 18,1997 DG support systems, particularly the lubricating oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite

power. This extended loss of auxiliary power caused the oil temperature to drop and that

resulted in oil pressure below the minimum pressure required for DG operation.

Discussion

The Millstone licensee reviewed the design and operation of the MC power source at

Millstone Unit 3 and determined that the AAC power source required modification to assure

availability of the SBO DG for no less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (the probable time needed to restore

offsite power) following a postulated LOOP event.

The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a

result of low oil temperature if power was lost to the lubricating oil keep-warm system for an

extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes, or modifications to SBO DG start logic.

The SBO DG capability to start on demand depends on the availability of the necessary

support systems to fulfill their required function. The SBO DG support systems may require

varying combinations of dc or ac power for varying periods to maintain operational readiness.

Prompt operator actions to conserve battery capacity, support system power supply

modifications, use of special procedures, or start logic modifications may be necessary to

preserve the operational readiness of the SBO DG under challenging environmental

conditions. The staff is evaluating these events and the consequential need for additional

generic communications.

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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: A. Pal, NRR David Skeen

(301) 415-2760 (301) 415-1174 E-mail: anp@nrc.gov E-mail: dls@nrc.gov

Thomas Koshy

(301) 415-1176 E-mail: txk@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: S:\DRPMSEC\97-21.lN *SEE PREVIOUS CONCURRENCES

To receive a copy of Us document, Indicate In the box: V' a Copy without enclosures "E" c Copy with enlosures "N" No copy

OFFICE TECH

CONTACT

S C:EELB CPECB D:DRPMl

NAME APa1* JCalvo* AChaffee* T~artin

DSkeen*_

DATE 04/07/97 04/07/97 04/11/97 04/ 97 OFFICIAL RECORD COPY

IN 97 -xx

April xx, 1997 DG support systems, particularly the lubricating oil system, was powered by a nonsafety- related power supply and had been out for an extended period during the loss of offsite

power. This extended loss of auxiliary power caused the oil temperature to drop and that

resulted in oil pressure below the minimum pressure required for DG operation.

Discussion

The Millstone licensee reviewed the design and operation of the MC power source at

Millstone Unit 3 and determined that the AAC power source required modification to assure

availability of the SBO DG for no less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (the probable time needed to restore

offsite power) following a postulated LOOP event.

The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a

result of low oil temperature if power was lost to the lubricating oil keep-warm system for an

extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes, or modifications to SBO DG start logic.

The SBO DG capability to start on demand depends on the availability of the necessary

support systems to fulfill their required function. The SBO DG support systems may require

varying combinations of dc or ac power for varying periods to maintain operational readiness.

Prompt operator actions to conserve battery capacity, support system power supply

modifications, use of special procedures, or start logic modifications may be necessary to- preserve the operational readiness of the SBO DG under challenging environmental

conditions. The staff is evaluating these events and the consequential need for additional

generic communications.

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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: A. Pal, NRR David Skeen

(301) 415-2760 (301) 415-1174 E-mail: anp@nrc.gov E-mail: dls@nrc.gov

Thomas Koshy

(301) 415-1176 E-mail: btk@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:%TXKXSBO.3 *SEE PREVIOUS CONCURRENCES

To receive a copy of this document, Indicate In the box: "C' = Copy wftiout enclosures "E - Copy with enclosures "N" No copy

OFFICE TECH

CONTACT

S I IC:EELB C I D: DRPM

NAME APal* JCalvo* AChaffee* TMartin

TKoshy

DSkeen*

DATE 04/07/97 04/07/97 04/11/97 04/ /97 OFFICIALTRECOR C/OPI

4 fX' q11V?7

  • lN 97 -xx

April xx, 1997 safety related power supply and had been out for an extended period during the loss of

offsite power. This extended loss of auxiliary power caused the oil temperature to drop and

that resulted in oil pressure below the minimum pressure required for DG operation.

Discussion

The Millstone licensee reviewed the design and operation of the AAC power source at

Millstone Unit 3 and determined that the AAC power source required modification to assure

availability of the SBO DG for no less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (the probable time needed to restore

offsite power) following a postulated LOOP event.

The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a

result of low oil temperature if power was lost to the lubricating oil keep-warm system for an

extended period. The licensee is considering enhanced monitoring of SBO DG auxiliaries, procedural changes or modifications to SBO DG start logic.

The SBO DG capability to start on demand depends on the availability of the necessary

support systems to fulfill their required function. The SBO DG support systems may require

varying combinations of dc or ac power for varying periods to maintain operational readiness.

Prompt operator actions to conserve battery capacity, support system power supply

modifications, use of special procedures, or start logic modifications may be necessary to

preserve the operational readiness of the SBO DG under challenging environmental

conditions. The staff is evaluating these events and the consequential need for additional

generic communications.

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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical Contacts: A. Pal, NRR Thomas Koshy David Skeen

(301) 415-2760 (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV TXK@NRC.GOV DLS@NRC.GOV

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:%TXKMSBO.3 To receive a copy of this document, Indicate In the box: "CT a Copy without enclosures "'Fn Copy with enclosures "N'u No copy

OFFICE TECH

CONTACT

S I :EELB T C:PECB lm DI IPIM

NAME APal* JCalvo* AChaffee TMartin

TKoshy

DSkeen*

DATE 04/07/97 04/07/97 04,1/97 104/ /97 OFFICIAL RECORD COPY

  • . I"7 -xx

March xx, 1997 safety related power supply and had been out for an extended period during the loss of

offsite power. This extended loss of auxiliary power caused the oil temperature to drop

and that resulted in oil pressure below the minimum pressure required for DG operation.

Discussion

The Millstone licensee reviewed the design and operation of the AAC power source at

Millstone Unit 3 and determined that the AAC power source required modification to

assure availability of the SBO DG for no less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (the probable time needed to

restore offsite power) following a postulated LOOP event.

The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a

result of low oil temperature if power was lost to the lubricating oil keep-warm system for

an extended period. The licensee is considering enhanced monitoring of SBO DG

auxiliaries, procedural changes or modifications to SBO DG start logic.

The SBO DG capability to start on demand depends on the availability of the necessary

support systems to fulfill their required function. The SBO DG support systems may

require varying combinations of dc or ac power for varying periods to maintain operational

readiness. Prompt operator actions to conserve battery capacity, support system power

supply modifications, use of special procedures, or start logic modifications may be

necessary to preserve the operational readiness of the SBO DG under challenging

environmental conditions. The staff is evaluating these events and the consequential need

for additional generic communications.

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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical Contacts: A. Pal, NRR Thomas Koshy David Skeen

(301) 415-2760 (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV TXK@NRC.GOV DLS@NRC.GOV

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\TXK\SBO.3 To receive a copy of this document. Indicate Inthe box: Ca- Copy without enclosures E - Copy with enclosures EN" = No copy

IOFFICE TECH

CONTACT

S C:EELB C:PECB D:DRPM

NAME APa1* JCalvo* AChaffee TMartin

TKoshy A

DSkeen*

DATE 1046997 /97 04/ 04/ /97 104/ /97 OFFICIAL RECORD WPY7

I 1W7-xx

March xx, 1997 safety related power supply and had been out for an extended period during the loss of

offsite power. This extended loss of auxiliary power caused the oil temperature to drop

below the minimum temperature required for DG operation.

Discussion

The Millstone licensee reviewed the design and operation of the AAC power source at

Millstone Unit 3 and determined that the AAC power source required modification to

assure availability of the SBO DG for no less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (the probable time needed to

restore offsite power) following a postulated LOOP event.

The Pilgrim licensee discovered that the SBO DG was susceptible to a failure to start as a

result of low oil temperature if power was lost to the lubricating oil keep-warm system for

an extended period. The licensee is considering enhanced monitoring of SBO DG

auxiliaries, procedural changes or modifications to SBO DG start logic.

The SBO DG capability to start on demand depends on the availability of the necessary

support systems to fulfill their required function. The SBO DG support systems may

require varying combinations of dc or ac power for varying periods to maintain operational

readiness. Prompt operator actions to conserve battery capacity, support system power

supply modifications, use of special procedures, or start logic modifications may be

necessary to preserve the operational readiness of the SBO DG under challenging

environmental conditions. The staff is evaluating these events and the consequential need

for additional generic communications.

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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical Contacts: A. Pal, NRR Thomas Koshy David Skeen

(301) 415-2760 (301) 415-1176 (301) 415-1174 E-mail:ANP@NRC.GOV TXK@NRC.GOV DLS@NRC.GOV

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:\TXK\SBO.3 To receive a copy of this document, Indicate in the box: 'C' - Copy without enclosures 'E" - Copy with enclosures N - No copy

OFFICE TECH

CONTACT

S I IC:EELB TI C:PECB I ID:DRPM I

NAME APa1* JCalvo* AChaffee TMartin

7Koshy

DSkeen*_

oats

DATE 04/? /97 04/ /97 04/ /97 04/ /97 OFFICIAL RECORD COPY


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