ML20136B566

Forwards Required Periodic Update of Dialog Between Plant & Vendor Re Recovered Battery Capacity Following Recharge

ML20136B566
Person / Time
Site:	McGuire, Mcguire
Issue date:	03/04/1997
From:	Barron H DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9703110028
Download: ML20136B566 (24)

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s Duke thaer Company H B Re.ssa

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DUKEPOWER March 4, 1997 U.S. Nuclear Regulatory Commicsion Document Control Desk Washington, D.C.

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Subject:

McGuire Nuclear Station Docket Nos: 50-369 and 50-370 AT&T Round Cell Battery'- Periodic Update i

Dear Sir:

Per our previous commitment on this issue, please find attached the required periodic update of the. dialog between McGuire and the vendor regarding recovered battery capacity following recharge.

If further information is required, please contact Kay L.

Crane, McGuire Regulatory Compliance at (704) 875-4306.

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's Very truly yours, pge WB 8end H. B. Barron, Vice President McGuire Nuclear Station 0\\

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s U. 'S. Nuclear Regulatory Commission Document Control Desk Page 2 cc:

Mr. Luis Reyes Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta St.,

NW, Suite 2900 Atlanta, GA 30323 Mr. Victor Nerses U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D.C.

20555 Mr. Scott Shaeffer NRC Senior Resident Inspector McGuire Nuclear Station 4

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. January 15,1997 Mr. James E. Snyder Regulatory Compliance Manager McGuire Nuclear Station 1

Subject:

AT&T Round Cell Battery Test Acceptance Criteria Periodic Update per 12/05/95 Letter to NRC, Commitment #3 j

PIP 0-M95-2131, Corrective Action #6 1

In letter dated 12/05/95, McGuire committed to become actively involved with the appropriate l

industry groups in resolving the battery test acceptance criteria issue. Due to the industry-wide nature of this issue, McGuire commits to work with the appropriate industry groups and provide l

periodic updates to the NRC. The following is an update status of this commitment:

' The AT&T Round Cell Nuclear Utility User's Council, chaired by Duke Power, has an approved Charter which identifies purpose, scope, operating agreement, expectations, and milestone dates.

Several of the Charter expectations are associated with battery test acceptance issues.

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In nuclear safety related applications, battery test acceptance criteria is documented in station specific Technical Specifications. Most battery Ter.hnical Specification surveillance requirements are influenced by IEEE Standards. Existing IEEE Standards do not identify individual j

manufactures, therefore applicability of AT&T Round Cell batteries with their unique characteristics are not fully understood. Duke Power has submitted in writing to the IEEE Standards Board, a request for interpretation ofIEEE Std 450 and IEEE Std 485 regarding Round Cell applicability. His interpretation request was addressed at the Spring IEEE SCC-29 battery meeting in Gulf Shores, Al. During the meeting, Lucent Technologies representatives a

stated that Round Cell should be applicable to both standards and are similar to conventional rectangular cells in most regards. He IEEE committee requested that Lucent Teichnologies provide technical justification to substantiate their statements, nerefore, the request for interpretation was deferred until additional information could be provided.

During the July 30-31,1996 User's Council meeting in Downers Grove, Illinois, the Council agreed that IEEE 450 applies to the Round Cell Battery. The Council also worked with Lucent Technologies to provide technicaljustification and recommendations requiring IEEE applicability to Round Cells. A letter with additional technicaljustification was submitted to the chairperson of the IEEE SCC-29 Committee Nuclear Task Group for consideration (Reference Attachment 1).

During the fall (1996) IEEE SCC-29 battery meeting in Trevose, Pennsylvania, the Nuclear Task Group supported Lucent Technologies position that IEEE-450 applies to Round Cells. The User's Council is waiting for a formal letter from the IEEE.

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Prior to the fall IEEE meeting, the User's Council submitted a letter of proposed rewording of IEEI! 450 and 485 (Reference Attachment 2). 'Ihe chairperson of User's Council presented j proposed changes during the fall IEEE meeting. The SCC-29 Nuclear Task Group accepted die proposed revisions to Section 6.3 ofIEEE 4501995 and Section 6.2.1 of IEEE 485-1983. The proposed revision to Section 7 of IEEE 450-1995 was not accepted. The User's Council Charter Expectation # 3," Identify and determine applicability ofIEEE Standards", is now documented as Complete. Charter Expectation #2," Identify and provide recommendations to resolve concems that apply to Technical Specifications", is pending until a formal letter is received from the IEEE.

A copy of the latest revision to the AT&T Round Cell Nuclear Utility User's Council Charter is included as Attachment 3.

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Danny L. Hepler McGuire Nuclear Station 4

Civil, Electrical, Nuclear Engineering cc w/ attachments:

J.W. Boyle R.W. Pierce W.N. Matthews K.L. Crane File MC-1356.01 1

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Mr. Kurt W. Uhlir Commonwealth Edison Company Nuclear Engineering and Technology Services 1400 Opus Place, Suite 400 Downers Grove,IL 60515

Dear Kurt,

During the recent IEEE meeting at Gulf Shores, AL, there was much discusion around IEEE-450 Section 5.2.c and its applicabili:y to the Round Cell. During the meeting Lucent Technologies agreed to draft its response to this issue.

BACKGROUND:

IEEE 450-1995 Section 5.2 addresser pcTormance testing of flooded lead-acid cells. In this section it states that a performance test should ba p:rformed within the first 2 years of service, and that this test should be similar in duration to the intwry duty cycle. Additional performance tests are to be performed at 5 year intervals ur.til signs of battery degradation appear. The test is to be performed annually thereafter until the battery needs to be replaced. Degradation is indics:cd when the battery capacity drops i

by more than 10% from the previous performance test, or performtm is below 90% of manufacturer's rating.

Battery replacernent criteria per Section 7 of the same document states that the battery shoutd le replaced if the capacity drops below 80% of the manufacturer's rating if the battery was sized using a 1.is ning factor. If a lessor aging fa: tor was used, replacement should occur before 80% capacity. Whenever replacement is required, the recommended maximum time for replacement is 1 year. Other factors such as an unsatisfactory service test (based on actual duty cycle) may also require replacement if the condition cannot be corrected.

ISSUE:

Should the Round Cc!! De subjected to different test and replacement criteria because documeritation states that the Round Cell capacity increases with age, and therefore, even a small capacity loss may be viewed as degradation? One position is that orJy a 5% loss of capacity for the Round Cell should be considered as degradation.

RESPONSE

The Round Cell is a pasted pk / %d-acid cell with featrres designed to significantly increase float life, reduce maintenance and incrm tait ty in standard tele munication applications of long term float and infrequent discharges. %.:lectro:hemistry _md fan..ae mechanisms are the same for the Round Cell as other pasted plate lead-acid v. signs except that the Round Cell design has virtually eliminated positive 4

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p, late grid corrosion and resulting loss of capacity caused by poor paste pellet-to-grid contact as a cause of failure. However, excessive cycling, premature capacity loss, manufacturing defects, impurity j

contamination, negative plate / expander problems, shipping damage, connector resistance, improper i

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maintenance, rectifier failure, etc. may also adversely affect cell performance The Round Cell product literature shows increasing capacity with age and lifetimes far greater than rectangular cells in accelerated life testing. De expected increase in capacity is due to the Round Cell's unique positive grid design. As the pure lead positive grid slowly corrodes (" grows"), the corrosion and pellet-to-grid contact is uniformly controlled by design throughout its lifetime. The predicted slope of capacity versus age is 0.3% per year over a 70 year period. In 1988,15 year old Round Cells were capacity tested on site at Xenia, Ohio. He capacity was approximately 5% greater than when first installed, and the actual positive grid growth was less than predicted. Figure 1 graphically presents this information. This data showed, at least to the 15 year point, that the theory behind the Round Cell positive plate design and the predicted valuer were as stated and that pcMive plate grid corrosion had been usentially eliminated as a failure mechaniarn.

i The Round Cell can still fail for other reasons including but not limited to those mentioned earlier. As an l

example, Figure 2 shows laboratory cycle life data for 6 different positive plate paste formulations. The test cells were subjected to a non-standard cycling regimen which included 4 shallow discharges for each deep discharge with excessive overcharge between discharges. The example demonstrates inat significant j

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performance variation in both the number of cycles and the rate of capacity loss can occur for causes independent of the long term effects of float service.

i' The IEEE performance test is an effective means ofidentifying capacity loss regardless of the cause of that i

loss. The cunently established 10% allowable window is based on the observed shape of the curve of capacity loss for rectangular cells due to grid corrosion as well as other factors. The propos*ed 5% window for the Round Cell simply because it is advertised to increase in capacity 0.3% per year is unreasonable.

P~+= War cell product literature show capacity increases greater than those reported for the Round Cell for a significant portion of their Wetised life, but the 10% window is not in question for those designs.

Five percent is less than the lirrM d experimental error and reproducibility from cycle to cycle. In addition, any capacity gain due to Round Cell grid growth is barely measurable within the first 10 years of i

float life.

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It is Lucent Technologies' position that a 5% limit for the Round Cell or any other cell design is an i

unreasonable requirement. The Round Cell does not fail from positive grid corrosion or seal leaks, but is otherwise substantially like other lead-acid designs and should therefore be subjected to the same performance criteria applicable to all lead-acid designs addressed in IEEE-450.

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2A S Michael Weeks copy with atts. to:

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i August 16,'1996 To:

EEE Standards Board, Secretary of Standards 445 Hoes Lane P.O. Box 1331 Piscataway, NJ. 08855-1331 1

Subject:

Proposed rewording of EEE 450 & 485 4

The Round Cell Nuclear Utility Users Council has been reviewing EEE battery standanis in the wake of present high specific gravity battery concems within the nuclear power industry. During our review we noted several items within EEE 450 and EEE 485 that we feel need better clarification. Some manufactures of batteries use different temperature correction factors than those stated in the standanis. 'Ihe notes in the EEE standards delineate this, but in the notes. It is our understanding that the notes within a EEE standard are not a official part of the standard. Out proposed changes involve placing the note information within the body of the standan!.

l We also noted that the recommended cell replacement in EEE 450 of 80%

- capacity was originally based on historical operating experience oflead acid cells and assumes a normal aging or failure mechanism of positive plate growth. What is not clear is if this recommended criteria is based on stationary batteries that are in a float application, a cycling application or both. It has been noted with high specific gravity round cells that cell capacity can be reduced by closely spaced deep cycling. Our proposed changes to Section 7 ofIEEE 450 calls attention to the factors that are relevant for determining when a battery should be replacement. With excess margin available the battery should be allowed to proceed providing the battery can meet its duty cycle.

A A.Y W ~ m William N. Matthews

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Chairperson - AT&T Round Cell Nuclear Utility User's Council Duke Power-McGuire Nuclear Station 12700 Hagers Ferry Road Huntersville, NC. 28708 cc:

Ash Agrawal - GPU, Oyster Creek Nuclear Station Robert Beavers - Comed, Electrical & I/C Engineering Judy Barleycom Arizona Public Service, Palo Verde Nuclear Station Bruce Kayser - Wolf Creek Nuclear Operating Corp.

Robert Koenig Comed, Braidwood Nuclear Station Kyle Sloyd, Southem Company Services, P.O. Box 2625 Bin B223. Birmingham. Al. 35202 Michael Weeks - Lucent Technologies, Bell Laboratories Kurt Uhlir - Comed. Comed Technical Center

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Proposed Change -IEEE 450 In Section 63 ofIEEE 4501995 the associated note states, "To determine the proper discharge parameters, the test discharge current or power rate is divided by the temperature correction factor as specified by table 1 for the initial electrolyte temperature. Table I can be usedfor all values ofspecific gravityforflood cells".

The note associated with Table 1 states "This table is based on nominal 1.210

. specific gravity cells. For cells with other specific gravity's, refer to the manufacturer.

The manufacturers recommend that battery testing be performed between 18.3 *C (65

• F) and 32.2 *C (90 *F) ".

It is our understanding that notes within IEEE documents are not deemed as a official part of the standards. Since several manufactures supply temperature correction factors different than those listed for 1. 210, it is suggested that both notes be deleted and the following paragraph be added to Section 63.

"The discharge current or power should be corrected for the temperature at the start of the discharge test by dividing the speci5ed current or power by a temperature correction factor. Table 1 list generic temperature correction factors that can be used if the manufacturer does not provide the factors. These factors are applicable to flooded cells for nominal 1.210 specific gravity. The manufacturers reconunend that battery testing be performed between 183 *C (65 'F) and 32.2 'C (90 *F) ".

In Section 7 of IEEE 450-1995 the following lines appear, "The timing of the replacement is a function of the sizing criteria utilized and the capacity margin, compared to the load requirements available. Whenever replacement is required, the l

recommended maximwn timefor replacement is one year. A capacity of 80% shows that the battery rate ofdeterioration is increasing even if there is ample capacity to meet the load requirements.".

Aging is one of the major contributors to cell failure, but there are other factors that reduce cell capacity which do not lead to rapid loss of cell capacity. Our experience with high gmvity round cells has shown that battery capacity can be suppressed by Premature Capacity Loss (PCL) when higher concentrations of acid are used in the

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electrolyte. This capacity loss can be restored by adjusting charging methodology or managing discharge recovery and recharge. It is recommended that the wording to Section 7 be revised to the following:

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"A capacity of 80% normally indicates that the rate of deterioration is increasing.

The timing of the replacement is a function of the sizing criteria utilized, the l

capacity margin and the degradation mechanism. Normally, replacement should bc l

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within one year. IIowever, an evaluation to determine the cause and rate of degradation may be performed to appropriate a scheduled replacement. Where ample apacity margin exist, extension of the replacement time is allowed, provided the evaluation demonstrates that the battery will continue to perform its intended function."

Pmposed Change -IEEE 485-1983 In Section 6.2.1 of IEEE 485-1983 the associated note states, " Table I lists cell size correction factorsfor various temperatures. For unlisted temperatures within the range of Table 1, interpolate between adjacent values and round off to two decimal places".

Table 1 has the following notes, " (1) These correction factors were developed from manufactures' published data. (2) Table 1 is applicable regardless of the capacity rating factor used. (see 633) and applies to all discharge rates."

It is our understanding that notes within IEEE documents are not deemed as a official part of the standards. Since several manufactures supply temperature correction factors different than those listed for 1. 210, it is suggested that both notes be deleted and the following paragraph be added to Section 6.2.1.

" Table 1 list generic temperature correction factors that can he used if the numufacturer does not provide the factors. These factors are applicable to flooded j

cells for nominal 1.210 specific gravity. Table 1 lists generic cell size correction factors for various temperatures. If these correction factors are used, interpolate between adjacent values and round off to two decimal places for unlisted temperatures within the ranges stated."

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CHARTER DATE:

November 12,1996 TITLE:

AT&T Round Cell Nuclear Utility User's Council 1

REVISION: 2 1

CIIAIR:

Duke Power l

MEMBERS: LucentTechnologies Arizona Public Service 5

Comed (Commonwealth Edison) 3 -

Duke Power Company GPU Nuclear Wolf Creek Nuclear Operating Corporation 4

t PURPOSE AND SCOPE:

The purpose of the User's Council is to bring together knowledge and experience of AT&T Lineage 2000 Round Cell Batteries in order to address immediate industry and regulatory concerns of performance and behavioral characteristics that have evolved from recent testing and operating experience. Long term, the team will collectively work to resolve questions and issues that are unique to Nuclear Utility applications and address applicability of IEEE standards.

OPERATING AGREEMENT:

The Council shall conduct business using Robert's Rules of Order. Group positions and rulings shall be established by consensus of majority members present at meetings. Urgent issues will be tesolved between meetings utilizing written correspondence and balloting of active members.

EXPECTATIONS:

1. Evaluate charging methods for high specific gravity Round Cells Available battery capacity following Performance Test recharge

. Available battery capacity Ibliowing an unplanned discharge on-line

2. Identify and resolve concenu that apply to Standard Technical Specilications I

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3. Identify and determine applicability oflEEE Standards I

4. Review historical problems and lessons learned

5. Develop position on testing and correlation ofintemal cell impedan.ce/ resistance to cell l

- performance

6. Investigate performance and behavioral characteristics of high and low specific Round Cells

7. Establish communication between member and methods of data pooling

8. Investigate root cause(s) of Palo Verde and Braidwood battery capacity loss MILESTONES GOALS:

+ Next Meeting in Charlotte, NC (completed)

- 5/22 & 23/96

+ Issue report documenting results of recharge testing

- 2/28/97 (revised)

+ Issue root cause reports for Palo Verde and Braidwood battery

- 12/31/96 (revised) loss of capacity

+ Issue report addressing cell impedance / resistance testing Vs cell

- Approx.

10/96 performance (completed)

+ Establish group position on applicability ofIEEE Standards

- Fall 96 IEEE Mtg and present to IEEE Standards Board (completed)

Document position and basis of Standard Technical Specification

- AfterIEEE Mtg

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Charter Attachment Page 1 of 8 Expectations Discussion / Action / Sponsor / Completion Date

1. Evaluate charging methods for high specific gravity Round Cells Available battery capacity following Performance Test recharge j

l Discussion: Discharge testing has indicated thal 100% capacity is not available immediately following recharging after a battery Performance Test. In order to fully understand this phenomenon, additional testing may need to be performed to determine the characteristics of constant current and connut potential charging.

Action: Evaluate and compare both constant current and constant pote.ntial charging.

Available battery capacity following an unplanned discharge on-line Discussion: After an unplanned discharge on-line, plants will use their permanent plant constant potential chargers at float potential to charge the batteries. An issue has been raised concerning the charge return rate using this method of charging and the available safety margin.

Action: Evaluate effectiveness of constant potential charging at float voltage following an on-line discharge. Determine rate of charge retum and evaluate safety margin over accident duty cycle. This effect should also address shallow repetitive discharges.

Sponsor: APS Completion Date:

Preliminary - Approx. 6/96 (compicted)

Final

- 2/28/97-Revised due to delays in testing. Scope of the test was redefined based on results of previous Lucent test.

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Charter Attactunent Page 2 of 8 l

Expectations Discussion / Action / Sponsor / Completion Date l

2. Identify and provide recommendations to resolve concerns that apply to Technical Specifications Discussion: With the unique characteristics of AT&T Round Cells, generic parameters and Surveillance Requirements need to be evaluated for applicability.

1 Action: Review Standardized Technical Specification for applicability. Document positions and basis.

Sponsor: APS Completion Date: (90 days following resolution ofIEEE 450 issue) ( Note-SCC 29 Nuclear Task Group supported Lucent's position that IEEE 450 applied to the Round.

Cells on 9/24/96. Waiting on formal letter from IEEE.)

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Charter Attachment Page 3 of 8 O

Expectations Discussion / Action / Sponsor / Completion Date

3. Identify and determine applicability ofIEEE Standards i

IEEE Std. 450 Discussion: Due to the unique design and characteristics, it has not been established or documented if AT&T Round Cells are covered by this standard.

Action: Determine if Round Cells are included in IEEE Std. 450. If so, to what extent and should differences be addressed. If Round Cells are not included, how and where should they be addressed. Request a Standards interpretation based on date submitted from User's Council.

IEEE Std 485 Discussion: IEEE Std. 485 is normally use i far sizing (including various margins) lead-acid batteries used at Nuclear Stations. The standard methodology uses battery performance discharge rates and curves published by battery manufactures. AT&T does not have data published in terms needed for battery sizing used by this Standard.

Performance data has been collected but not officially published by Lucent Technologies.

Action: Request a Standards interpretation based on data submitted from User's Council.

Sponsor: APS Completion Date: (Request submitted prior to fall 96 IEEE, Working Group meeting)

Status: The Council determined that IEEE 450 and 485' applies to the AT&T Round Cell l

Battery. Minor revisions were submitted and accepted by the IEEE SCC 26 Nuclear Task Force for Section 6.3 ofIEEE 450-1995 and Section 6.2.1 ofIEEE 485-1983. The Nuclear Task Force also agreed with Lucent Technologies that IEEE 450 applies to Round Cells. Completed

Charter Attachment Page 4 of 8 l

l Expectations Discussion / Action / Sponsor / Completion Date

4. Review historical problems and lessons learned Discussion: Significant problems and lessons learned during service need to be shared with the group from both a historical perspective and on-going basis.

Action: Research problem history and record on-going problems and lessons learned.

Solicit input and share with the group.

Sponsor: GPUN Completion Date: Initial Rollout Approx. 6/96 Status: Completed 4'

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Charter Attaciunent

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Page 5 of 8 Expectations Discussion / Action / Sponsor / Completion Date

5. Develop position on testing and correlation ofinternal cellimpedance/ resistance to cell performance Discussion: Comed, Braidwood Nuclear Station has been taking internal cell impedance measurements on designated strings of Round Cells and comparing values with battery Pe'ormance Test results. The emphasis is to establish a correlation between cell impedance and capacity. This testing also explores the effect of entrapped gases generated during charging on cell impedance.

Action: Document test results and determine validity of correlation and benefits of impedance testing.

Sponsor: Comed Completion Date: Approx.10/96 Status: Reference Attaclunent 5 of the September 23,1996, meeting minutes (completed).

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Charter Attachment Page 6 of 8 e

r Expectations l

Discussion / Action / Sponsor / Completion Date

6. Investigate performance and behavioral characteristics of high and low specific gravity Round Cells Discussion: Recent problems and abnormalities of Round Cells have been limited to those with high specific gravity electrolyte. The effects of high specific gravity electrolyte on performance and behavioral characteristics are not fully understood.

Action: Investigate perfomiance and behavioral characteristics of high and low specific gravity cells. Determine and document differences of each.

Sponsor: WolfCreek Completion Date: Approx. 4/97 4'

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usarter Attachment' Page 7 of 8 s

Expectations Discussion / Action / Sponsor / Completion Date

7. Establish communication between members and methods of data pooling Discussion: With national participation, the User's Council member locations are such that frequent meetings are impractical. In order to share ideas and data, a more direct method ofcommunication is needed.

Action: Develop a network between Council members using the Internet, that will provide convenient distribution of correspondence, information, and test data. Method should be fast, simple and convenient such that frequent correspondence and sharing of data is encouraged.

Sponsor: Duke Power Completion Date: Approx. 6/96 Status: Completed W

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Expectations Discussion / Action / Sponsor / Completion Date

8. Investigate root cause(s) of Palo Verde and 11raidwood battery capacity loss Discussion: Recent Performance Tests of Round Cell batteries at Palo Verde Unit 2 and Braidwood Unit I have indicated unexpected and premature loss of capacity. Root cause evaluations at each station are ongoing. The results of these evaluations should be reviewed and shared such that lessons are learned and applied to develop a better understanding of Round Cell behavior.

Action: Investigate root cause(s) ofcapacity loss and evaluate results.

Sponsor: APS/ Comed Completion Date: 12/31/96 (Revised to correspond to NRC commitment date.)

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