ML20203D692

Discusses Initial Review of Commonwealth Edison Co Submittal Dtd 971015,which Util Responded to Staff Request for Addl Info.Informs That Initial Review on Methodololgy for EOC SG Tube Leakage Under Postulated Accident Not Acceptable

ML20203D692
Person / Time
Site:	Byron, Braidwood
Issue date:	11/13/1997
From:	Lynch M NRC (Affiliation Not Assigned)
To:	Johnson I COMMONWEALTH EDISON CO.
References
TAC-M97894, TAC-M97895, TAC-M99535, TAC-M99536, NUDOCS 9712160266
Download: ML20203D692 (7)

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• NUCLEAR REGULATORY GQMMISSION

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g***** november 13, u 8 E I9 UI & 4'l PUBUC 00cunEng noon Ms. Irene Johnson, Acting Manager i Nudear Regulatory Services i I- Commonwealth Edison Company  :

Executive Towers West 111 1400 Opus Place, Suite 500 ]

Downers Grove,IL 60515 PROJECTED BRAIDWOOD STATION, UNIT 1, ENL N CYCLE STEAM  !

8UBJECT:

GENERATOR TUBE LEAKAGE DUE TO OUTER DIALETER STRESS CORROSION CRACK INDICATIONS RESTRICTED FROM BURST (1 AC NOS. M97894, M97895, M99535 AND M99536) ,

Dear Ms. Johnson:

t We have conducted an initial review of Commonwealth Edison Company's (Comed) submittal -

4 , dated October 15,1997, in which Comed responded to the staff's request for additional Information (RAI) issued on October 7,1997. Based on this initial review, we find that we can

( not accept Comed's proposed methodology for estimating the end of cycle (EOC) steam

. generator (SG) tube leakage under postulated accident conditions for both Byron Station, Unit 1, and Braidwood Station, Unit 1. Tliis projected SG tube leakage is attributable to outer diameter stress corrosion crack (ODSCC) indications left in service in accordance with the e license amendments issued for Byron Station, Unit 1, and Braidwood Station, Unit 1. on

November 9,1995. ,

- In this regard, the Braidwood and Byron Stations, Units 1, apply a 3.0 voit interim plugging criteria (IPC) to ODSCC Indications located at the tube support plates (TSP). This repair limit is higher than that allowed by Generic Letter (GL) 95-05 because Comed stabilized the TSP by ,

expanding selected tubes at the support plate intersections so that the TSP would be displaced ,

only a small distance under postulated main steamline break (MSLB) conditions. Braidwood  !

l Station, Unit 1, implemented the 3.0 volt IPC at the EOC-5. Byron Station, Unit 1, implemented the 3.0 volt IPC during a Cycle 7 midcycle inspection.

During the Braidwood Station, Unit 1, spring 1997 outage ut the EOC-6, Comed compared I

the actual bobbin coil oddy current voltage distribution of its ODSCC TSP indications with -

the predicted voltage distribution and found that the predicted voltage distribution was

, nonconservative with respect to the actual voltage distribution. As a result, the predicted /

leakage during a postulated MSLB event significantly underestimated the leakage calculated based on actual EOC conditions; i.e.,6.90 gallons per minute (gpm) versus 11.5 gpm. The 9 ,

letter value was still within the Braidwood Station, Unit 1, site allowable leakage limit of 19.0 gpm. At a meeting with the staff on July 23,1997, Comed attributed the nonconservative prediction of the EOC voltage distribution to voltage-dependent growth rates which appear to j have occurred, in part, due to the higher voltage repair criteria in effect at Braidwood Station, ,'

Unit 1 (i.e., the 3.0 volt IPC). For the current Braidwood Station, Unit 1, operating cycle l

I- (Cycle 7), Comed subsequentty revised its methodology and applied voltage-dependent growth rates to predict the Braidwood Station, Unit 1, EOC-7 conditions. Comed also revised the ,,_-

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EOC-8 predictions for Byron Station, UnN 1, since a similar ydWndent growth rate may ,

exist. Based on EOC predictions that incorporated voli+-4,e,,ded growth rates, both

! stations concluded that the reactor coolant system dose equivalent lodme (DEI) concentration levels should be reduced. ,

4 As part of its review of the pending DEI level reduction license amendment requests for Byron - j Station, Unit 1, and Braidwood Station, Unit 1, the staff reviewed Comed proposed voltage- i dependent growth rate methodology. This methodology was submitted on August 14,1997, in

the Braidwood Station, UnN 1,90< lay report. Based on our review of this submittal, the staff 1

issued an RAI on October 7,1997. Comed submitted its response to the RAI on October 15, '

.1997.

! The intent of this RAI was to determine the sensitivity of the projected EOC leakage to the

! assumptions in Comed's proposed methodology. Comed's RAI response indicates that the  ;

, projected EOC SG tube leakage can very from about 57 gpm to about 68 gpm for the three hybrid methodologies Comed evaluated. Comed's response also indicates that a change in the lower voltage limit from 1.10 volts to 1.45 volts of the largest voltage _ indications left in service

' (i.e., the binning strategy), would increase the projected EOC primary to secondary leakage up to . '

100 gpm. In reviewing the results and discussion in Comed's RAI response, we find that there is insufficient data available to justify Comed's proposed methodology. Furthermore, the sensitivity discussed above leads us to conclude we can not accept Comed's proposed methodology for

. predicting the SG tube EOC leakage during a postulated MSLB event for Braidwood Station, Unit 1. Although our conclusion also applies to Byron Station, Unit 1, the issue is not as  ;

significant since strong voltage-dependent growth rates at Byron Station, Unit 1, have not been .

apparent and the Byron Station, Unit 1, SG are being replaced during the outage that begin in earty November 1997.

We informally told Comed's representative of our initial positions on Comed's RAI response on October 22,1997, to permit Con.Ed to consider whether to go forward with the meeting

, previously scheduled for October 24,1997, to discuss these matters. We indicated to Comed's '

representative that since the staff was sufficiently concemed about the lack of data to

! substantiate Comed's proposed methodology, we believed that Comed should address this issue from a larger perspective. Namely, we request that Comed provide justification for not conducting a mid-cycle inspechon of the ODSCC flaw indications left in service in the Braidwood i

Station, Unit 1, SG in accordance with the present 3.0 voit IPC. Finally, we believe that Comed's

' current administrative del limit for Breldwood Station, Unit 1, may not be sufficiently  ;

conservative, in this regard, it is our understandmg that Comed is presently considering a program to address the NRC's concems on these matters.

Since the predicted SG tube leakage increases with operating time at temperature, it is important that Comed address this issue in a timely manner. Accordingly, please respond within 30 days s from the date of this letter.

I We note that the two license amendment requests to reduce the del limits for Byron Station, 3 Unit 1, and Braidwood Station, Unit 1, had lapses in their quality control. Specifically, the Byron Station, Unit 1, amendment request had numerous small errors in the assessment of radiation exposure doses which required several Comed submittels to resolve. The Braidwood Station, b

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. Ms. Irene Johnson 3-Unit 1, amendment request had several small errors in the hard copy evaluation of the standards in 10 CFR 50.92 while the electronic version of this same evaluation submitted on I

disk had a large number of errors. While all of these problems were smallin nature, they did cause the staff to expend significant resources to correct them. Accordingly, we encourage Comed to avoid such problems in the future by ensuring close coordination between the personnel at the Byron and Braidwood Stations and the corporate staff at Downers Grove, if there are any questions regarding these matters, please contact me at (301) 415-3023.

Sincerely, OrthsisteedDr M. David Lynch, Senior Project Manager Project Directorate 111-2 Division of Reactor Projects - fil/IV Office of Nuclear Reactor Regulation Docket Nos. STN 50-454 and STN 50-456 4

cc: See next page DISTRIBUTION:

Docket PUBLIC ~ F0lli-2 r/f E. Adensam, EGA1 R. Capra C. Moore D. Lynch OGC,015B18 ACRS, T2E26 M. Jordan, Rlli G. Dick S. Bailef S. Coffin C. Beardslee E. Sullivan J. Strosnider G. Lainas B. Sheron C. Hinson R. Emch C. Miller J. Gavula, Rlli M. Holmberg, Rlli

• See previous concurrence DOCUMENT NAME: G:\CMNTJR\ BRAID \BRSG.EOC To receive a copy of this document, indicate in the box: "C" = Copy without enclosures "E" = Copy with i enclo*ures "N" = No copy OFFICE @i T LA:PCS2 EMCB* l D:PD32 E NAME' ff6C6(V) CMdOhE ESULLIVAN RCAPRA >

DATE 11//3 /9T~ 6 - 11/ )3 /97 11/10/97 11/t 3 197 OFFICIAL RECORD COPY

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. Ms. Irene Johnson 3 Unit 1, amendment request had several small errors in the hard copy evaluation of the standards in 10 CFR 50.92 while the electronic version of this same evaluation submitted on disk had a large number of errors. While all of these problems were smallin nature, they did  !

cause the staff to expend significant resources to correct them. Accordingly, we encourage l Comed to avoid such problems in the future by ensuring close coordination between the l personnel at the Byron and Braidwood Stations and the corporate staff at Downers Grove.

l if there are any questions regarding these matters, please contact me at (301) 415 3023.

j Sincerely, MEMedDV' M. David Lynch, Senior Project Manager Project Directorate 1112 Division of Reactor Projects - lil/IV  ;

Office of Nuclear Reactor Regulation ,

I Docket Nos. STN 50-454 and STN 50-456 cc: See next page DISTRIBUTION:

Docket PUBLIC PDill 2 r/f E. Adensam, EGA1 R. Capra C. Moore D. Lynch OGC,015B18 ACRS, T2E26 M. Jordan, Rlli G. Dick S. Bailey S. Coffin C. Beardslee E. Sullivan J. Strosnider G. Lainas B. Sheron C. Hinson R. Emch C. Miller J. Gavula, Rill M. Holmberg, Rill

• See previous concurrence DOCUMENT NAME: G:\CMNTJR\ BRAID \BRSG.EOC To receive a copy of this document, Indicate in the box: "C" = Copy without enc;osures "E" = Copy with enclosures "N" = No copy OFFICE M T LA:PDB2 EMCB' l D:PD32 E NAME d[Yl65(i(V) cudOkE ESULLIVAN RCAPRA 9.~

QATE 11//9 /97 6 11/13 /97 11/10/97 11/13 /97 OFFICIAL RECORD COPY

i Ms. Irene Johnson 3 Unit 1, amendment request had several small errors in the hard copy evaluation of the standards in 10 CFR 50.92 while the electronic version of this same evaluation submitted on disk had a large number of errors. While all of these problems were smallin nature, they did cause the staff to expend significant resources to correct them. Accordingly, we encourage Comed to avoid such problems in the future by ensuring close coordination between the I personnel at the Byron and Braidwood Stations and the corporate staff at Downers Grove. P l

if there are any questions regarding these matters, please contact me at (301) 415-3023.  !

Sincerely, W^_

• M. David Lynch, Senior Project Manager Project Directorate 1112 Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket Nos. STN 50-454 and STN 50-456 cc: See next page i

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- . . l 4 1. Johnson Byron /Braidwood Power Stations Commonwealth Edison Company cc:

Mr. William P. Poirier, Director George L Edgar  !

Westinghouse Electric Corporation Morgan, Lewis and Bochius i Energy Systems Business Unit 1800 M Street, N.W.

Post Office Box 355, Bay 236 West Washington, DC 20036 Pittsburgh, Pennsylvania 15230 Attomey General Joseph Gallo 500 South Second Street Gallo & Ross Springfield, Illinois 62701 l 1250 Eye St., N.W. l Suite 302 EIS Review Coordinator Washington, DC 20005 U.S. Environmental Protection Agency 77 W. Jackson Blvd.

Michael 1. Miller, Esquire Chicago, Illinois 60604-3590 Sidley and Austin One First National Plaza Illinois Department of Chicago, Illinois 60603 Nuclear Safety Office of Nuclear Facility Safety Howard A. Leamer 1035 Outer Park Drive Environmentallaw and Policy Springfield, Illinois 62704 Center of the Midwest 203 North LaSalle Street Commonwealth Edison Company Suite 1390 Byron Station Manager Chicago, Illinois 60601 4450 North German Church Road Byron,lilinois 61010 U.S. Nuclear Regulatory Commission Byron Resident inspectors Office Kenneth Graesser, Site Vice President 4448 North German Church Road Byron Station Byron, Illinois 61010 9750 Commonwealth Edison Station 4450 N. German Church Road Regional Administrator, Region 111 Byron, Illinois 61010 U.S. Nuclear Regulatory Commission 801 Warrenville Road U.S. Nuclear Regulatory Commission Lisle, I!Iinois 60532 4351 Braidwood Resident inspectors Office Rural Route #1, Box 79 Ms. Lorraine Creek Braceville, Illinois 60407 Rt.1, Box 182 Manteno, Illinois 60950 Mr. Ron Stephens lilinois Emergency Services Chairman, Ogle County Board and Disaster Agency Post Office Box 357 110 East Adams Street Oregon, Illinois 61061 Springfield, Illinois 62706 Mrs. Phillip B. Johnson Chairma6 1907 Stratford Lane Will County Board of Supervisors Rockford, Illinois 61107 Will County Board Courthouse Joliet, Illinois 60434

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• Commonwealth Edison Company Braidwood Station Mana0er ,~

Rt.1, Box 84 '

Braceville,lilinois 60407 ,

Ms. Bridget Little Rotem i Appleseed Coordmator 117 North Linden Street  !

Essex, Illinois 60935 i Document Control Desk Uoensing ,

Commonwealth Edison Company 1400 Opus Place, Suite 400 ,

Downers Grove, Illinois 60515  ;

Mr. T. J. Tulon Site Vice President i Braidwood Station Commonwealth Edison Company -

i RR 1, Box 84 _

Braceville,IL 60407  ;

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