Information Notice 1997-21, Availability of Alternate AC Power Source Designed for Station Blackout Event
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
April 18, 1997
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
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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
(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
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Attachment 1
April 18, 1997 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
97-20
97-19
94-14, Supp. 1
97-18
97-17
Identification of
Certain Uranium
Hexafluoride Cylinders
that do not comply
with ANSI N14.1 Fabrication
Standards
Safaty Injection
System Weld Flaw at
Sequoyah Nuclear
Power Plant, Unit 2
Failure to Implement
Requirements for
Biennial Medical
Examinations and
Notification to the
NRC of Changes in
Licensed Operator
Medical Conditions
Problems Identified
During Maintenance
Rule Baseline Inspections
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 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
(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
(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
I
C/OP
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
(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 "'F
n 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
(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
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
(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