Information Notice 2013-05, Battery Expected Life and Its Potential Impact on Surveillance Requirements: Difference between revisions

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{{#Wiki_filter:ML122130601 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION OFFICE OF NEW REACTORS WASHINGTON, DC 20555-0001 March 19, 2013 NRC INFORMATION NOTICE 2013-05: BATTERY EXPECTED LIFE AND ITS POTENTIAL IMPACT ON SURVEILLANCE REQUIREMENTS
{{#Wiki_filter:UNITED STATES
 
NUCLEAR REGULATORY COMMISSION
 
OFFICE OF NUCLEAR REACTOR REGULATION
 
OFFICE OF NEW REACTORS
 
WASHINGTON, DC 20555-0001 March 19, 2013 NRC INFORMATION NOTICE 2013-05:                   BATTERY EXPECTED LIFE AND ITS POTENTIAL
 
IMPACT ON SURVEILLANCE REQUIREMENTS


==ADDRESSEES==
==ADDRESSEES==
All holders of an operating license or construction permit for a nuclear power reactor under Title 10 of the
All holders of an operating license or construction permit for a nuclear power reactor under
 
Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of
 
Production and Utilization Facilities, except those who have permanently ceased operations


Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities," except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.
and have certified that fuel has been permanently removed from the reactor vessel.


All holders or applicants for a combined license under 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants."
All holders or applicants for a combined license under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants.


==PURPOSE==
==PURPOSE==
The U.S. Nuclear Regulatory Commission (NRC) is is
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform
 
addressees about recent issues involving licensees nonconservative technical specifications
 
(TSs) regarding surveillance requirements (SRs) for direct current (DC) power systems due to
 
reductions in battery expected life. The NRC expects that recipients will review the information


suing this information notice (IN) to inform addressees about recent issues involving licensees' nonconservative technical specifications (TSs) regarding surveillance requirements (SRs) for direct current (DC) power systems due to reductions in battery expected life.  The NRC expects that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems.
for applicability to their facilities and consider actions, as appropriate, to avoid similar problems.


Suggestions contained in this IN are not NRC requirements; therefore, no specific action or written response is required.
Suggestions contained in this IN are not NRC requirements; therefore, no specific action or
 
written response is required.


==BACKGROUND==
==BACKGROUND==
Class 1E batteries are used to supply DC loads at nuclear power plants and are designed
Class 1E batteries are used to supply DC loads at nuclear power plants and are designed


consistent with the requirements in General Design Criterion (GDC) 17, "Electric Power Systems," and GDC 18, "Inspection and Testing of Electric Power Systems," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50 or similar plant-specific
consistent with the requirements in General Design Criterion (GDC) 17, Electric Power
 
Systems, and GDC 18, Inspection and Testing of Electric Power Systems, of Appendix A,
General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50 or similar plant-specific


design criteria.
design criteria.


The Class 1E batteries are lead-acid batteries which degrade over time, primarily as a result of the buildup of lead sulfates on the plates. The battery manufacturer's typical expected battery life curve indicates a 100 percent battery capacity over the initial 14 years of service. The capacity then decreases to 80 percent at the end of the expected 20-year life. At this point, the
The Class 1E batteries are lead-acid batteries which degrade over time, primarily as a result of
 
the buildup of lead sulfates on the plates. The battery manufacturers typical expected battery
 
life curve indicates a 100 percent battery capacity over the initial 14 years of service. The
 
capacity then decreases to 80 percent at the end of the expected 20-year life. At this point, the


Institute of Electrical and Electronics Engineers (IEEE) Standard (Std.) 450-2002, "IEEE
Institute of Electrical and Electronics Engineers (IEEE) Standard (Std.) 450-2002, IEEE


Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid
Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid


Batteries for Stationary Applications," as endorsed by Regulatory Guide 1.129, "Maintenance, Testing, and Replacement of Vented Lead-Acid Storage Batteries for Nuclear Power Plants," recommends replacing the battery bank. To account for this degradation, IEEE Std. 485-1997,  
Batteries for Stationary Applications, as endorsed by Regulatory Guide 1.129, Maintenance, Testing, and Replacement of Vented Lead-Acid Storage Batteries for Nuclear Power Plants, recommends replacing the battery bank. To account for this degradation, IEEE Std. 485-1997, IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications, as
"IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications," as
 
endorsed by Regulatory Guide 1.212, Sizing of Large Lead-Acid Storage Batteries, recommends that when sizing batteries for use at nuclear power plants, the rated capacity of the


endorsed by Regulatory Guide 1.212, "Sizing of Large Lead-Acid Storage Batteries," recommends that when sizing batteries for use at nuclear power plants, the rated capacity of the battery, when put in service, should be at least 125 percent of the design load. This ensures
battery, when put in service, should be at least 125 percent of the design load. This ensures


that at least 80 percent of the battery nameplate capacity will be available at the end of the
that at least 80 percent of the battery nameplate capacity will be available at the end of the
Line 55: Line 87:
load (80 percent of 125 percent equals 100 percent).
load (80 percent of 125 percent equals 100 percent).


The NRC requires licensees to maintain batteries in
The NRC requires licensees to maintain batteries in an operable condition as specified in plant
 
TS. As such, the batteries must be capable of performing their intended function of supplying
 
100 percent of design DC loads. Standard TSs have a SR to Verify battery capacity is  80%
of the manufacturer's rating when subjected to a performance discharge test or a modified
 
performance discharge test. The specified frequency of this surveillance is 60 months AND


an operable condition as specified in plant TS.  As such, the batteries must be capable of performing their intended function of supplying
12 months when battery shows degradation, or has reached 85% of the expected life with


100 percent of design DC loads.  Standard TSs have a SR to "Verify battery capacity is  80% of the manufacturer's rating when subjected to a performance discharge test or a modified
capacity < 100% of manufacturers rating AND 24 months when battery has reached 85% of the


performance discharge test."  The specified frequenc
expected life with capacity  100% of manufacturers rating. Note that the surveillance


y of this surveillance is "60 months AND 12 months when battery shows degradation, or has reached 85% of the expected life with capacity < 100% of manufacturer's rating AND 24 months when battery has reached 85% of the
frequency uses the term expected life but does not include a specific value (e.g., 20 years).


expected life with capacity  100% of manufacturer's rating."  Note that the surveillance frequency uses the term "expected life" but does not include a specific value (e.g., 20 years).
Because of this, licensees may not be immediately aware of the impact changes to the


Because of this, licensees may not be immediately aware of the impact changes to the expected life of their Class 1E batteries can have on their plant's TS SRs.
expected life of their Class 1E batteries can have on their plants TS SRs.


==DESCRIPTION OF CIRCUMSTANCES==
==DESCRIPTION OF CIRCUMSTANCES==
In the examples below, the licensees discovered conditions that either increased battery design
In the examples below, the licensees discovered conditions that either increased battery design


loads or decreased rated battery capacity such that the battery no longer met the sizing design basis. The batteries remained operable, at least in the near term, as the batteries were still capable of supplying 100 percent of the design DC loads. However, the licensees did not
loads or decreased rated battery capacity such that the battery no longer met the sizing design
 
basis. The batteries remained operable, at least in the near term, as the batteries were still
 
capable of supplying 100 percent of the design DC loads. However, the licensees did not


recognize the need to ensure the "expected life" of Class 1E batteries appropriately accounted
recognize the need to ensure the expected life of Class 1E batteries appropriately accounted


for the sizing requirements and post-accident DC loading assumptions contained in design
for the sizing requirements and post-accident DC loading assumptions contained in design


basis documents. As a result, certain TS SR testing frequencies, specifically those associated with performance or modified performance discharge testing, were nonconservative.
basis documents. As a result, certain TS SR testing frequencies, specifically those associated
 
with performance or modified performance discharge testing, were nonconservative.


===Cooper Nuclear Station===
===Cooper Nuclear Station===
On March 11, 2009, the licensee for Cooper Nuclear Station submitted a license amendment
On March 11, 2009, the licensee for Cooper Nuclear Station submitted a license amendment


request to address nonconservative TSs regarding the SRs for 125 volt (V) and 250 V DC
request to address nonconservative TSs regarding the SRs for 125 volt (V) and 250 V DC


power systems. During its review of the amendment, the NRC staff noted that
power systems. During its review of the amendment, the NRC staff noted that a reduction in the


a reduction in the expected service life would be needed to ensure the batteries would be capable of providing 90 percent of their rated capacity at the end of their service life. The NRC issued a request for additional information that requested the licensee to describe t
expected service life would be needed to ensure the batteries would be capable of providing 90
percent of their rated capacity at the end of their service life. The NRC issued a request for


he impact of this change on the expected life of Cooper Nuclear Station batteries (e.g., conclusions drawn from the battery life
additional information that requested the licensee to describe the impact of this change on the


versus capacity curv
expected life of Cooper Nuclear Station batteries (e.g., conclusions drawn from the battery life


e for the batteries).
versus capacity curve for the batteries).


In its response to the NRC staffs' request for addi
In its response to the NRC staffs request for additional information, the licensee noted that as


tional information, the licensee noted that as loads have increased over time, the required battery capacity is now closer to 90 percent of the nameplate rating.  The licensee further stated that its battery vendor does not estimate battery life for 90 percent capacity.  Therefore, the licensee conservatively established 15 years as the
loads have increased over time, the required battery capacity is now closer to 90 percent of the


point at which the batteries reach 85 percent of expected life. The licensee also conservatively
nameplate rating. The licensee further stated that its battery vendor does not estimate battery


defined battery degradation to be when capacity drops by more than 5 percent (normally 10
life for 90 percent capacity. Therefore, the licensee conservatively established 15 years as the
percent as defined by the IEEE Std. 450-2002,) relative to the capacity on the previous performance test or when the battery capacity reaches less than or equal to 95 percent of the manufacturer's rating (normally 90 percent or when it is 10 percent below the manufacturer's


rating as defined by IEEE Std. 450-2002). On March 18, 2010, the NRC issued the above mentioned license amendment for Cooper Nuclear Station. To address the above concern, the NRC staff required the licensee to update
point at which the batteries reach 85 percent of expected life. The licensee also conservatively
 
defined battery degradation to be when capacity drops by more than 5 percent (normally 10
percent as defined by the IEEE Std. 450-2002,) relative to the capacity on the previous
 
performance test or when the battery capacity reaches less than or equal to 95 percent of the
 
manufacturers rating (normally 90 percent or when it is 10 percent below the manufacturers
 
rating as defined by IEEE Std. 450-2002). On March 18, 2010, the NRC issued the above mentioned license amendment for Cooper
 
Nuclear Station. To address the above concern, the NRC staff required the licensee to update


its updated safety analysis report and TS bases for the batteries upon implementation of the
its updated safety analysis report and TS bases for the batteries upon implementation of the


approved license amendment. These updates included the reduction to 15 years as the point at
approved license amendment. These updates included the reduction to 15 years as the point at


which the safety-related batteries have reached 85 percent of expected life. See the licensee
which the safety-related batteries have reached 85 percent of expected life. See the licensee


amendment issuance package for further details (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100610233).
amendment issuance package for further details (Agencywide Documents Access and
 
Management System (ADAMS) Accession No. ML100610233).


Indian Point Nuclear Generating, Unit 2 (IP2)
Indian Point Nuclear Generating, Unit 2 (IP2)
On March 29, 2009, the licensee for IP2 submitted a license amendment request to address
nonconservative TSs regarding SR 3.8.6.6 in TS section 3.8.6, Battery Parameters, for 125 V
DC power systems. The SR verifies battery capacity during a performance discharge test or a


On March 29, 2009, the licensee for IP2 submitted a license amendment request to address nonconservative TSs regarding SR 3.8.6.6 in TS section 3.8.6, "Battery Parameters," for 125 V DC power systems.  The SR verifies battery capacity during a performance discharge test or a
modified performance discharge test. The licensee discovered that the 80 percent capacity


modified performance discharge test.  The licensee discovered that the 80 percent capacity
value was nonconservative with respect to the existing design basis calculation for battery


value was nonconservative with respect to the existing design basis calculation for battery capacity under minimum design temperature conditions. The licensee determined that it should implement a more restrictive battery acceptance criterion ( 85 percent of manufacturers rating) to ensure that sufficient battery capacity exists at limiting conditions.  During its review of the
capacity under minimum design temperature conditions. The licensee determined that it should


amendment, the NRC staff identified that the licensee for IP2 applied a 117.6 percent (1.176)  
implement a more restrictive battery acceptance criterion ( 85 percent of manufacturers rating)
aging factor in its design calculation for sizing the Class 1E batteries. While the aging factor is
to ensure that sufficient battery capacity exists at limiting conditions. During its review of the
 
amendment, the NRC staff identified that the licensee for IP2 applied a 117.6 percent (1.176)
aging factor in its design calculation for sizing the Class 1E batteries. While the aging factor is


less than that recommended by IEEE Std. 485-1997, the licensee followed this guidance since
less than that recommended by IEEE Std. 485-1997, the licensee followed this guidance since


the aging factor is appropriate for the assumed end-of-life criterion (i.e., 85 percent). However, based on standard battery life versus capacity curves, the licensee noted that aging these batteries to 85 percent of rated capacity would indicate an expected battery life of approximately
the aging factor is appropriate for the assumed end-of-life criterion (i.e., 85 percent). However, based on standard battery life versus capacity curves, the licensee noted that aging these
 
batteries to 85 percent of rated capacity would indicate an expected battery life of approximately


18 years versus 20 years
18 years versus 20 years originally assumed.


originally assumed.
On February 24, 2010, the NRC issued the above mentioned license amendment for IP2. To


On February 24, 2010, the NRC issued the above mentioned license amendment for IP2.  To address the above concern, the NRC staff required
address the above concern, the NRC staff required the licensee to update its battery monitoring


the licensee to update its battery monitoring and maintenance program, TS bases for the batteries, and updated final safety analysis report
and maintenance program, TS bases for the batteries, and updated final safety analysis report


upon implementation of the approved license amendment. These updates included the
upon implementation of the approved license amendment. These updates included the


reduction to 18 years as the expected life of their safety-related batteries. See the licensee
reduction to 18 years as the expected life of their safety-related batteries. See the licensee


amendment issuance package for further details (ADAMS Accession No. ML100270051).
amendment issuance package for further details (ADAMS Accession No. ML100270051).
Line 147: Line 214:
Licensees rely on Class 1E batteries to supply DC loads when battery chargers are not
Licensees rely on Class 1E batteries to supply DC loads when battery chargers are not


available. The batteries are sized in accordance with IEEE Std. 485-1997 to carry the expected
available. The batteries are sized in accordance with IEEE Std. 485-1997 to carry the expected
 
shutdown loads following a plant trip and a loss of all alternating current power without battery


shutdown loads following a plant trip and a loss of all alternating current power without battery terminal voltage falling below its minimum required voltage. This ensures that adequate DC power will be available for starting and loading the emergency diesel generators, emergency
terminal voltage falling below its minimum required voltage. This ensures that adequate DC
 
power will be available for starting and loading the emergency diesel generators, emergency


power to run instrumentation and controls, and emergency lighting.
power to run instrumentation and controls, and emergency lighting.
Line 155: Line 226:
IEEE Std. 485-1997, recommends applying at least a 125 percent (1.25) aging factor when
IEEE Std. 485-1997, recommends applying at least a 125 percent (1.25) aging factor when


sizing batteries for nuclear power plants, to ensure the battery can perform its design function with a greater than or equal to 80 percent capacity rating throughout its 20-year life.  When using an aging factor less than 1.25, the result is a reduction in expected life of the batteries
sizing batteries for nuclear power plants, to ensure the battery can perform its design function


based on the manufacturers expected life versus capacity curves. The licensees identified above were not immediately aware that an increase in battery design loads or a decrease in
with a greater than or equal to 80 percent capacity rating throughout its 20-year life. When


rated battery capacity would result in a reduced expected life of the batteries. Certain TS SR testing frequencies, specifically those associated with performance and modified performance discharge testing, are directly tied to the expected life of batteries. The once per 60-month performance discharge test (which is based on 25 percent of a 20-year expected life) and the increased TS SR frequencies (i.e., 12 and 24 months), when batteries reach 85 percent of
using an aging factor less than 1.25, the result is a reduction in expected life of the batteries
 
based on the manufacturers expected life versus capacity curves. The licensees identified
 
above were not immediately aware that an increase in battery design loads or a decrease in
 
rated battery capacity would result in a reduced expected life of the batteries. Certain TS SR
 
testing frequencies, specifically those associated with performance and modified performance
 
discharge testing, are directly tied to the expected life of batteries. The once per 60-month performance discharge test (which is based on 25 percent of a 20-year expected life) and the
 
increased TS SR frequencies (i.e., 12 and 24 months), when batteries reach 85 percent of


expected life, are consistent with the guidance provided in IEEE Std. 450 and are tied to known
expected life, are consistent with the guidance provided in IEEE Std. 450 and are tied to known


age-related degradation of vented lead-acid batteries. The events described in this IN illustrate
age-related degradation of vented lead-acid batteries. The events described in this IN illustrate


the importance of considering the impact of a decrease in the battery expected life on plant TS
the importance of considering the impact of a decrease in the battery expected life on plant TS
Line 170: Line 253:


==CONTACT==
==CONTACT==
This IN requires no specific action or written response. Please direct any questions about this
This IN requires no specific action or written response. Please direct any questions about this


matter to the technical contacts listed below or the appropriate NRC project manager.
matter to the technical contacts listed below or the appropriate NRC project manager.


/RA/       /RA/  
/RA/                                                 /RA/
Lawrence E. Kokajko, Director Laura A. Dudes, Director Division of Policy and Rulemaking   Division of Construction Inspection Office of Nuclear Reactor Regulation     and Operational Programs
Lawrence E. Kokajko, Director                         Laura A. Dudes, Director
 
Division of Policy and Rulemaking                     Division of Construction Inspection
 
Office of Nuclear Reactor Regulation                   and Operational Programs


Office of New Reactors
Office of New Reactors


Technical Contacts: Matthew McConnell, NRR
Technical Contacts:   Matthew McConnell, NRR
 
301-415-1597 E-mail: Matthew.McConnell@nrc.gov
 
Sergiu Basturescu, NRR
 
301-415-1237 E-mail: Sergiu.Basturescu@nrc.gov
 
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library.


301-415-1597   E-mail: Matthew.McConnell@nrc.gov
ML122130601                        *via e-mail    TAC MF0492 OFFICE   NRR/DE/EEEB*      Tech Editor*        NRR/DE/EEEB/BC      NRR/DE/D          NRR/DPR/PGCB/PM


Sergiu Basturescu, NRR  301-415-1237  E-mail: Sergiu.Basturescu@nrc.gov
NAME    MMcConnell        CHsu                JAndersen          PHiland          ARussell


Note:  NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library.
(RMathew for)
DATE    02/13/13          01/18/13            02/14/13            02/14/13          02/19/13 OFFICE  NRR/DPR/PGCB/LA NRR/DPR/PGCB/BC NRO/DCIP/D                NRR/DPR/DD        NRR/DPR/D


ML122130601  *via e-mail TAC MF0492 OFFICE NRR/DE/EEEB* Tech Editor* NRR/DE/EEEB/BC NRR/DE/D NRR/DPR/PGCB/PM NAME MMcConnell CHsu JAndersen (RMathew for) PHiland ARussell  DATE 02/13/13 01/18/13 02/14/13 02/14/13 02/19/13 OFFICE NRR/DPR/PGCB/LA NRR/DPR/PGCB/BCNRO/DCIP/D NRR/DPR/DD NRR/DPR/D NAME CHawes, (GLappert
NAME     CHawes, (GLappert DPelton              LDudes              SBahadur          LKokajko


for) DPelton LDudes SBahadur LKokajko DATE 02/19/13 03/04/13 03/14/13 03/18/13 03/19/13}}
for)
DATE     02/19/13           03/04/13           03/14/13           03/18/13         03/19/13}}


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

Revision as of 01:27, 12 November 2019

Battery Expected Life and Its Potential Impact on Surveillance Requirements
ML122130601
Person / Time
Issue date: 03/19/2013
From: Laura Dudes, Kokajko L
Division of Construction Inspection and Operational Programs, Division of Policy and Rulemaking
To:
Russell A
References
TAC MF0492 IN-13-005
Download: ML122130601 (5)
v • d • e


UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

OFFICE OF NEW REACTORS

WASHINGTON, DC 20555-0001 March 19, 2013 NRC INFORMATION NOTICE 2013-05: BATTERY EXPECTED LIFE AND ITS POTENTIAL

IMPACT ON SURVEILLANCE REQUIREMENTS

ADDRESSEES

All holders of an operating license or construction permit for a nuclear power reactor under

Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of

Production and Utilization Facilities, except those who have permanently ceased operations

and have certified that fuel has been permanently removed from the reactor vessel.

All holders or applicants for a combined license under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants.

PURPOSE

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

addressees about recent issues involving licensees nonconservative technical specifications

(TSs) regarding surveillance requirements (SRs) for direct current (DC) power systems due to

reductions in battery expected life. The NRC expects that recipients will review the information

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

Suggestions contained in this IN are not NRC requirements; therefore, no specific action or

written response is required.

BACKGROUND

Class 1E batteries are used to supply DC loads at nuclear power plants and are designed

consistent with the requirements in General Design Criterion (GDC) 17, Electric Power

Systems, and GDC 18, Inspection and Testing of Electric Power Systems, of Appendix A,

General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50 or similar plant-specific

design criteria.

The Class 1E batteries are lead-acid batteries which degrade over time, primarily as a result of

the buildup of lead sulfates on the plates. The battery manufacturers typical expected battery

life curve indicates a 100 percent battery capacity over the initial 14 years of service. The

capacity then decreases to 80 percent at the end of the expected 20-year life. At this point, the

Institute of Electrical and Electronics Engineers (IEEE) Standard (Std.) 450-2002, IEEE

Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid

Batteries for Stationary Applications, as endorsed by Regulatory Guide 1.129, Maintenance, Testing, and Replacement of Vented Lead-Acid Storage Batteries for Nuclear Power Plants, recommends replacing the battery bank. To account for this degradation, IEEE Std. 485-1997, IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications, as

endorsed by Regulatory Guide 1.212, Sizing of Large Lead-Acid Storage Batteries, recommends that when sizing batteries for use at nuclear power plants, the rated capacity of the

battery, when put in service, should be at least 125 percent of the design load. This ensures

that at least 80 percent of the battery nameplate capacity will be available at the end of the

20-year expected life of the batteries, which will be sufficient to serve 100 percent of the design

load (80 percent of 125 percent equals 100 percent).

The NRC requires licensees to maintain batteries in an operable condition as specified in plant

TS. As such, the batteries must be capable of performing their intended function of supplying

100 percent of design DC loads. Standard TSs have a SR to Verify battery capacity is 80%

of the manufacturer's rating when subjected to a performance discharge test or a modified

performance discharge test. The specified frequency of this surveillance is 60 months AND

12 months when battery shows degradation, or has reached 85% of the expected life with

capacity < 100% of manufacturers rating AND 24 months when battery has reached 85% of the

expected life with capacity 100% of manufacturers rating. Note that the surveillance

frequency uses the term expected life but does not include a specific value (e.g., 20 years).

Because of this, licensees may not be immediately aware of the impact changes to the

expected life of their Class 1E batteries can have on their plants TS SRs.

DESCRIPTION OF CIRCUMSTANCES

In the examples below, the licensees discovered conditions that either increased battery design

loads or decreased rated battery capacity such that the battery no longer met the sizing design

basis. The batteries remained operable, at least in the near term, as the batteries were still

capable of supplying 100 percent of the design DC loads. However, the licensees did not

recognize the need to ensure the expected life of Class 1E batteries appropriately accounted

for the sizing requirements and post-accident DC loading assumptions contained in design

basis documents. As a result, certain TS SR testing frequencies, specifically those associated

with performance or modified performance discharge testing, were nonconservative.

Cooper Nuclear Station

On March 11, 2009, the licensee for Cooper Nuclear Station submitted a license amendment

request to address nonconservative TSs regarding the SRs for 125 volt (V) and 250 V DC

power systems. During its review of the amendment, the NRC staff noted that a reduction in the

expected service life would be needed to ensure the batteries would be capable of providing 90

percent of their rated capacity at the end of their service life. The NRC issued a request for

additional information that requested the licensee to describe the impact of this change on the

expected life of Cooper Nuclear Station batteries (e.g., conclusions drawn from the battery life

versus capacity curve for the batteries).

In its response to the NRC staffs request for additional information, the licensee noted that as

loads have increased over time, the required battery capacity is now closer to 90 percent of the

nameplate rating. The licensee further stated that its battery vendor does not estimate battery

life for 90 percent capacity. Therefore, the licensee conservatively established 15 years as the

point at which the batteries reach 85 percent of expected life. The licensee also conservatively

defined battery degradation to be when capacity drops by more than 5 percent (normally 10

percent as defined by the IEEE Std. 450-2002,) relative to the capacity on the previous

performance test or when the battery capacity reaches less than or equal to 95 percent of the

manufacturers rating (normally 90 percent or when it is 10 percent below the manufacturers

rating as defined by IEEE Std. 450-2002). On March 18, 2010, the NRC issued the above mentioned license amendment for Cooper

Nuclear Station. To address the above concern, the NRC staff required the licensee to update

its updated safety analysis report and TS bases for the batteries upon implementation of the

approved license amendment. These updates included the reduction to 15 years as the point at

which the safety-related batteries have reached 85 percent of expected life. See the licensee

amendment issuance package for further details (Agencywide Documents Access and

Management System (ADAMS) Accession No. ML100610233).

Indian Point Nuclear Generating, Unit 2 (IP2)

On March 29, 2009, the licensee for IP2 submitted a license amendment request to address

nonconservative TSs regarding SR 3.8.6.6 in TS section 3.8.6, Battery Parameters, for 125 V

DC power systems. The SR verifies battery capacity during a performance discharge test or a

modified performance discharge test. The licensee discovered that the 80 percent capacity

value was nonconservative with respect to the existing design basis calculation for battery

capacity under minimum design temperature conditions. The licensee determined that it should

implement a more restrictive battery acceptance criterion ( 85 percent of manufacturers rating)

to ensure that sufficient battery capacity exists at limiting conditions. During its review of the

amendment, the NRC staff identified that the licensee for IP2 applied a 117.6 percent (1.176)

aging factor in its design calculation for sizing the Class 1E batteries. While the aging factor is

less than that recommended by IEEE Std. 485-1997, the licensee followed this guidance since

the aging factor is appropriate for the assumed end-of-life criterion (i.e., 85 percent). However, based on standard battery life versus capacity curves, the licensee noted that aging these

batteries to 85 percent of rated capacity would indicate an expected battery life of approximately

18 years versus 20 years originally assumed.

On February 24, 2010, the NRC issued the above mentioned license amendment for IP2. To

address the above concern, the NRC staff required the licensee to update its battery monitoring

and maintenance program, TS bases for the batteries, and updated final safety analysis report

upon implementation of the approved license amendment. These updates included the

reduction to 18 years as the expected life of their safety-related batteries. See the licensee

amendment issuance package for further details (ADAMS Accession No. ML100270051).

DISCUSSION

Licensees rely on Class 1E batteries to supply DC loads when battery chargers are not

available. The batteries are sized in accordance with IEEE Std. 485-1997 to carry the expected

shutdown loads following a plant trip and a loss of all alternating current power without battery

terminal voltage falling below its minimum required voltage. This ensures that adequate DC

power will be available for starting and loading the emergency diesel generators, emergency

power to run instrumentation and controls, and emergency lighting.

IEEE Std. 485-1997, recommends applying at least a 125 percent (1.25) aging factor when

sizing batteries for nuclear power plants, to ensure the battery can perform its design function

with a greater than or equal to 80 percent capacity rating throughout its 20-year life. When

using an aging factor less than 1.25, the result is a reduction in expected life of the batteries

based on the manufacturers expected life versus capacity curves. The licensees identified

above were not immediately aware that an increase in battery design loads or a decrease in

rated battery capacity would result in a reduced expected life of the batteries. Certain TS SR

testing frequencies, specifically those associated with performance and modified performance

discharge testing, are directly tied to the expected life of batteries. The once per 60-month performance discharge test (which is based on 25 percent of a 20-year expected life) and the

increased TS SR frequencies (i.e., 12 and 24 months), when batteries reach 85 percent of

expected life, are consistent with the guidance provided in IEEE Std. 450 and are tied to known

age-related degradation of vented lead-acid batteries. The events described in this IN illustrate

the importance of considering the impact of a decrease in the battery expected life on plant TS

SRs.

CONTACT

This IN requires no specific action or written response. Please direct any questions about this

matter to the technical contacts listed below or the appropriate NRC project manager.

/RA/ /RA/

Lawrence E. Kokajko, Director Laura A. Dudes, Director

Division of Policy and Rulemaking Division of Construction Inspection

Office of Nuclear Reactor Regulation and Operational Programs

Office of New Reactors

Technical Contacts: Matthew McConnell, NRR

301-415-1597 E-mail: Matthew.McConnell@nrc.gov

Sergiu Basturescu, NRR

301-415-1237 E-mail: Sergiu.Basturescu@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library.

ML122130601 *via e-mail TAC MF0492 OFFICE NRR/DE/EEEB* Tech Editor* NRR/DE/EEEB/BC NRR/DE/D NRR/DPR/PGCB/PM

NAME MMcConnell CHsu JAndersen PHiland ARussell

(RMathew for)

DATE 02/13/13 01/18/13 02/14/13 02/14/13 02/19/13 OFFICE NRR/DPR/PGCB/LA NRR/DPR/PGCB/BC NRO/DCIP/D NRR/DPR/DD NRR/DPR/D

NAME CHawes, (GLappert DPelton LDudes SBahadur LKokajko

for)

DATE 02/19/13 03/04/13 03/14/13 03/18/13 03/19/13


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