ML20199D138

Discusses Notification,Per 10CFR50.72 That Both Byron Station Unit 1 & Braidwood Station Unit 1 Are Outside Design Bases

ML20199D138
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 9711200267
Download: ML20199D138 (6)

Text

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NUCLEAR REGULATORY COMMISSION-WAsHINeToN, D.C. 30086 00lH

• • • • • .Ilovember 13, 1997

- Ms. Irene Johnson, Acting Manager Nuclear Regulatory Services -  :

Commonwealth Edison Company Executive Towers West lli 9 1400 Opus Place, Suite 500 j Downers Grove, IL 60515 ,

SUBJECT:

COMED NOTIFICATIONS PURSUANTTO 10 CFR 50.72 THAT BOTH BYRON STAh0N, UNIT 1, AND BRAIDWOOD STATION, UNIT 1, ARE OUTSIDE

' THEIR DESIGN BASES (TAC NOS. M97894, M97895, M99535 AND M99536)

Dear Ms. Johnson:

On October 7,1997, the Commonwesith Edison Company (Comed) notified the Nuclear Regulatory Commission (Event No. 33040) pursuant to 10 CFR 50.72(b)(1)(ii)(B) that Byron Station, Unit 1, was outside its design basis for offsite radiation dose exposures. On October 10,1997, a similar notification (Event No. 33062) was made for Braidwood Station, Unit 1.- One of the factors cited in these two notifications contributing to the projected increase.

In the primary-to-secondary leakage over that projected in prior Byron Station, Unit 1, and Braidwood Station, Unit 1, fuel cyc es, is steam generator (SG) tube leakage attributable to circumferential crack indications,

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p However, in our letter dated March 28,1997, regarding Comed's proposed extension of the '

i ~ Byron Station, Unit 1, maximum operating cycle between SG eddy current inspections (ECl), the l staff contluded that Comed's proposal to extend the present operating cycle (i.e., Cycle 8) from 448.5 days to 540 days above a T,,,, of 500 degrees Fahrenheit, was acceptable. The stars E review in this area 'ncluded information Comed had provided relative to the structural and L leakage integrity o the SG tubes dus to the occurrence of circumferential crack indications at the top of the tube sheet in the roll transition zone. This issue arose due to the relatively large '

number of circum 'erential crack indications (e.g., about 6000) found in the Byron Station, Unit 1, SG during the provious ope sting cycle (i.e., Cycle 7).

The staff's conc:asion cited above was based on our review of the quclitative considerations associated with Comed's' prior SG tube inspections as well as Comed's quantitative cycle

. length assessmeat. However, since the staff found that there was insufficient data to support a correlation between voltages found during an ECl and SG tube leakage attributable to >

circumferential crack indications, it was unable to accept Comed's quantitative assessment.

Accordingly, the stats acceptance of Comed's proposal for an extended Byron Station, Unit 1, operating cycle war based solely on our finding that the additional qualitative measures cited in Comed's letter dated January 7,1997, would provide reasonable assurance that large _

throughwall, free span circumferentie! cracks would not develop during the present Byron Station, Unit 1, operating cycle.1These measures included: (1) more sensitive eddy current E probes; (2) data analysis software with features to facilitate the detection of circumferential 7

- indications in the roll transition zone; (3) the' pulling and destructive metallurgical examination of ,

ten SG tubes in the October 1995 outage at Byron Statior; Unit 1; (4) the in-situ pressure tests .

MJ J fIg 9711200267 971113 f_ ucpu2 RRllBl(Ml 20 R.E CERE 08py PDR: ADOCK 05000454 (p . PDR _ __ _ , , _ _. .- _ _ _ _ - __ _

. . q V c. Ms. Irene Johnson 2 in the April 1996 outage at Byron Station, Unit 1, of a, sample of SG tubes containing the most significant circumferential indications; and (5) additional defense-in-depth measures cited in our letter dated March 28,1997. .The staffs finding was that as a result of Comed's aggressive approach to this issue, circumferential flaws that could become potentially significant defects at

- the end of Cycle 8 for Byron Station, Unit 1, were likely to have been detected and removed

. from service.- Further, any small circumferential crack indications below the threshold of detection and, therefore, neither repaired nor removed from service, would not grow to the extent of extending throughwall based on Comed's look back review of past ECis at Byron, Unit 1. Accordingly, it was the staffs position that all of the qualitative measures cited above, when taken as a whole, had the not effect of reducing to a very low value, the probability of throughwall, free span SG tube leakage from circumferential indications in the Byron Station, - 4 Unit 1, SG. It was our understanding when we issued our letter of March 28,1997, that this was also Comed's position. The staff concluded that these qualitative measures were also applicable to this issue in the Braidwood Station, Unit 1, SG.

The staff is concemed that the two 10 CFR 50.72 notifications cited above appear to contradict our prior findings that the qualitative measures Comed implemented at Byron Station, Unit 1, and Braidwood Station, Unit 1, reduced to a very low value, the probability of throughwall, freespan lockage from circumferential cracks. Accordingly, state whether Comed has changed its position on this issue. Furthermore, indicate whether Comed has obtained additional

~ information or performed any other analyses that could affect our evaluation or understanding of -

the bases for Comed's prior proposals to operate both Byron Station, Unit 1, and Braidwood Station, Unit 1, without any midcycle eddy current inspections for circumferential crack indications. In this regard, state whether Comed has conducted a re review of Comed's ECl data from prior inspections which might affect Comed's prior position that the circumferential crack indications found in the Byron Station, Unit 5, SG had taken several operating cycles to

( develop, if there are any questions on these issues. please contact me at (301) 415-3023.

The staff believes that the apparent reversal of Comed's prior position in the two 10 CFR 50.72 1- notifications cited above regarding the low probability of throughwall, freespan SG tube leakage attributable to :ircumfersntial crack indications, may have arisen from a lapse in the quality control of these notifications. Assuming this to be the case, 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.

l l- Sincerely nn A w- t -

M; David Lynch, Senior Project Manager Project Directorate lll-2 Division of Reactor Projects - I!!/lV Office of Nuclear Reactor Regulation Docket Nos. STN 50-454 and STN 50-456 cc: See next page

=a-  ; *

• Ms. Irene Johnson '

in the April 1996 outage at Byron Station, Unit 1, of a sample of SG tubes containing the most significant circumferential indications; and (5) additional defense-in-depth measures cited in our letter dated March 26,1997. The staff's finding was that as a result of Comed's aggressive approach to this issue, circumferential flaws that could become potentially significant defects at the end of Cycle 8 for Byron Station, Unit 1, were likely to have been detected and removed from service. Further, any small circumferential crack indications below the threshold of detection and, therefore, neither repaired nor removed from service, would not grow to the extent of extending throughwall based on Comed's look back review of past ECis at Byron, Unit 1. Accordingly, it was the staff's position that all of the qualitative measures cited above, when taken as a whole, had the not effect of reducing to a very low value, the probability of throughwall, free span SG tube leakage from circumferential indications in the Byron Station, Unit 1, SG, it was our understanding when we issued our letter of March 28,1997, that this was also Comed's position. The staff concluded that these qualitative measures were also applicable to this issue in the Braidwood Station, Unit 1, SG.

The staff is concemed that the two 10 CFR 50.72 notifications cited above appear to contradict our prior findings that the qualitative measures Comed implemented at Byron Station, Unit 1, and Braidwood Station, Unit 1, reduced to a very low value, the probability of throughwall, freespan leakage from circumferential cracks. Accordingly, state whether Comed has changed its position on this issue. Furthermore, indicate whether Comed has obtained additional information or performed any other analyses that could affect our evaluation or understanding of the bases for Comed's prior proposals to operate both Byron Station, Unit 1, and Braidwood Station, Unit 1, without any midcycle eddy current inspections for circumferential crack l

indications. In this regard, state whether Comed has conducted a re-review of ComEdis ECl l

data from prior inspections which might affect Comed's prior position that the circumferential crack indications found in the Byron Station, Unit 1, SG had taken several operating cycles to develop. If there are any questions on these issues, please contact me at (301) 415-3023.

The staff believes that the apparent reversal of Comed's prior position in the two 10 CFR 50.72 notifications cited above regarding the low probability of throughwall, freespan SG tube leakage attributable to circumferential crack indications, may have arisen from a lapse in the quality l

control of these notifications. Assuming this ' be the case, we encourage Comed to avoid l such problems in the future by ensuring clos coordination between the personnel at the Byron and Braidwood Stations and the corporate staff at Downers Grove.

Sincerely, OilpnalSIGCMi:

M. David Lynch, Senior Project Manager Project Directorate ill-2 Division of Reactor Projects - lil/IV Office of Nuclear Reactor Regulation R. Assa Docket Nos. STN 50-454 and STN 50-456 }STRIBUTION: Docket R. Capra RJBLIC PDill-2 r/f C. Moore

, cc: See next page E. Adensam, EGA1 D. Lynch C. Miller M. Jordan, Rill OGC,015B18 ACRS, T2E26 G. Dick S. Bailey M. Holmberg, Rill S. Coffin C. Beardslee E. Sullivan J. Strosnider G. Lainas B. Sheron C. Hinson R. Emch J. Gavula, Rlli l DOCUMENT NAME: G:\ BRAID-BY\BBNOTIF.EOC *See previous concurrence io w= . m or w. * ,= io,*A uene c conv maa -- m c=v e -%. -w wo ennv G

OFFICE PJWO , LA:lfDI2 b EMCB* D:PD32 NAME 9tTP@N } BMODf(E ESULLIVAN RCAPPA W DATE 11//gl9FUT 11 6 /97 11/10/97 11/ft/97 OFFICIAL RECORD COPY

I Ms. Irene Johnson =2-in the April 1996 outage at Byron Station, Unit 1, of a sample of SG tubes containing the most significant circumferential indications; and (5) additional defense-in-depth measures cited in our letter dated March 28,1997. The staff's finding was that as a result of Comed's aggressive approach to this issue, circumferential flaws that could become potentially significant defects at the end of Cycle 8 for Byron Station, Unit 1, were likely to have been detected and removed from service. Further, any small circumferential crack indications below the threshold of detection and, therefore, neither repaired nor removed from service, would not grow to the extent of extending throughwall based on Comed's look back review of past ECis at Byron, Unit 1. Accordingty, it was the staff's position that all of the qualitative measures cited above, when taken as a whole, had the net effect of reducing to a very low value, the probability of throughwall, free span SG tube leakage from circumferential indications in the Byron Station, Unit 1, SG. It was our understanding when we issued our letter of March 28,1997, that this was also Comed's position. The staff concluded that these qualitative measures were also applicable to this issue in the Braidwood Station, Unit 4, SG.

The staff is concemed that the two 10 CFR 50.72 notifications cited above appear to contradict ou: prior findings that the qualitative measures Comed implemented at Byron Station, Unit 1, and Braidwood Station, Unit 1, reduced to a very low value, the probability of throughwall, freespan leakage from circumferential cracks. Accordingly, state whether Comed has changed its position on this issue. Furthermore, indicate whether Comed has obtained additional information or performed any other analyses that could affect our evaluation or understanding of the bases for Comed's prior proposals to operate both Byron Station, Unit 1, and Braidwood Station, Unit 1, without any midcycle eddy current inspections for circumferential crack indications. In this regard, state whether Comed has conducted a re-review of Comed's ECl data from prior inspections which might affect Comed's prior position that the circumferential crack indications found in the Byron Station, Unit 1, SG had taken several operating cycles to develop. If there are any questions on these issues, please contact me at (301) 415-3023.

The staff believes that the apparent reversal of Comed's prior position in the two 10 CFR 50.72 notifications cited abovt, regarding the low probability of throughwall, freespan SG tube leakage attributable to circumferential crack indications, may have arisen from a lapse in the quality control of these notifications. Assuming this to be the case, 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.

Sincerely, Oil;!nalSignSy:

M. David Lynch, Senior Project Manager Project Directorate 111-2 Division of Reactor Projects - lil/IV Office of Nuclear Reactor Regulation R. Assa Docket Nos. STN 50-454 and STN 50-456 JSTRIBUTION: Docket R. Capra

%)BLIC PDill-2 r/f C. Moore cc: See next page E. Adensam, EGA1 D. Lynch C. Miller M. Jordan, Rlli OGC,015B18 ACRS, T2E26 G. Dick S. Bailey M. Holmberg, Rlli S. Coffin C. Beardslee E. Sullivan J. Strosnider G. Lainas B. Sheron C. Hinson R. Emch J. Gavula, Rill DOCUMENT NAME: G:\ BRAID BYTBBNOTIF.EOC *See previous concurrence Altsglye a cony ofihlidQCumenklDdiC4Lbidhe bor "C" = Coev Mhout em!c:iures

• E* = Cocy w'th emknures "N" =.lh.CC2Y..

OFFICE J P HNd I LA:RD32 [_ EMCB* D:PD32 l G NAME 9tTMQN ) CMOORE ESULLIVAN RCAPRA W DATE 11/dl9M/T 11/A #97 11/ 10 /97 11/ft/97 OFFICIAL RECORD COPY

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Byron /Braidwood Power Stations

-* = 1. Johnson- -

Commonwealth Edison Company - _

oc: .i

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

Westinghouse Electric Corporation Morgan, Lewis and Bochius Energy Systems Business Unit ' 1800 M Street, N.W. =i Post Offlos Box 355, Bay 236 West- Washington, DC 20036 .

Pittsburgh, Pennsylvania 15230 Attomey General-Joseph Gallo 500 South Second Street =

Gallo & Ross _-

Spnngfield, Illinois 62701 1250 Eye St., N.W.

- Suite 302 - EIS ReviewCoordinator 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 lilinois Department of Chicago, Illinois 60603 Nuclear Safety-Office of Nuclear Facility Safety Howard A. Leamer 1035 Ou'or 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,Illiaois 60601 4450 North German Church Road Byron, Illinois 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,liiinois 61010 i- U.S. Nuclear Regulatory Commission

. 801 Warrenville Road U.S. Nuclear Regulatory Commission Lisle, Illinois 60532-4351 Braidwood Resident inspectors Office

- Rural Route #1, Box 79 -

Ms. Lorraine Creek Braceville, Illinois 60407 Rt.1, Box 182

- Mantono, Illinois 60950 Mr. Ron Stephens filinois 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 Chairman 1907 Stratford Lane Will County Board of Supervisors Rockford, Illinois 61107 Will County Board Courthouse Joliet, Illinois 60434

' - Commonwealth Edison Company Braidwood Station Manager Rt.1, Box 64 Bracevjile, Illinois 60407 Ms. Bridget Uttle Rorem -

Appleseed Coordinator 117 teorth unden Street Essex,lilinois 60g35 Document Control Desk-Ucensing Commonwealth Edison Company 1400 Opus Place, Suite 400 Downers Grove, Illinois 60515 Mr. T. J. Tulon Site Vice President Braidwood Station Commonwealth Edison Company RR 1, Box 84 Braceville,IL 60407

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