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 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 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 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
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 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
"'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 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
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 oats DSkeen*_DATE 04/? /97 04/ /97 04/ /97 04/ /97 OFFICIAL RECORD COPY