ML20134B365

Requests Addl Info Re Proposed Extension of Byron I & Braidwood I 3.0 Volt License Amends for Outer Diameter Stress Corrosion Cracking

ML20134B365
Person / Time
Site:	Byron, Braidwood
Issue date:	01/27/1997
From:	Lynch M NRC (Affiliation Not Assigned)
To:	Johnson I COMMONWEALTH EDISON CO.
References
NUDOCS 9701300057
Download: ML20134B365 (7)

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-y-j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. enana nant -

\ ug/ January 27, 1997 Ms. Irene-Johnson, Acting' Manager Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West III 1400 Opus Place, Suite 500 Downers Grove, IL 60515

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE PPOPOSED EXTENSION OF THE BYRON 1 AND BRAIDWOOD 1 3.0 VOLT LICENSE AMENDMENTS FOR ODSCC

Dear Ms. Johnson:

On November 9,1995, the staff issued license amendments for Byron, Units 1 and 2 and for Braidwood, Units I and 2 related to raising the Technical Specification-(TS) value of the lower voltage repair limit for steam generator (SG) tubes subject to outer diameter stress corrosion cracking (ODSCC), from 1.0 volt to 3.0 volts on the hot leg side. The lower voltage repair limit remained at 1.0 volt on the cold leg <:de. The thrust of these amendments was to allow all ODSCC indications on the hot. leg side less than 3.0 volts, detected by an eddy current inspection (ECI) in Byron I and Braidwood 1, to remain in service subject to certain restrictions in the TSs and as discussed in the safety evaluation issued with the subject license amendments.

- One of these restrictions was that the TSs related to the revised voltage

! repair criteria for ODSCC for Braidwood I would be applicable only to the end i of the operating cycle scheduled to be completed in spring 1997. A similar restriction applied to Byron 1 for the fuel cycle presently scheduled to end

! near December 1997. With respect to this latter license amendment, the F Commonwealth Edison Company (Comed) has subsequently stated that it intends to replace the Byron 1 SGs by the end of 1997.

i In its letter dated August 19, 1996, Comed submitted a request to extend for

! one more operating cycle, the applicability of the license amendments cited

above for both Braidwood I and Byron 1. The request for the latter unit was l submitted so that in the event that the delivery of the replacement SGs for

Byron I was inadvertently delayed, Byron 1 could be restarted using the SGs

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now in service after its next scheduled refueling outage (i.e., December 1997) using the present TS value of the lower voltage repair limit for the hot leg side (i.e., 3.0 volts) for 00 SCC indications.

-During the course'of our review of_the proposed license amen (ments, we have

identified a need for further information. This request for additional l '- \

9701300057 970127 I

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information=(RAI) is contained in the' enclosure to this letter. If you have '

any questions.on these matters, please contact,Mr. M. David Lynch at

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(301) 415-3023.' p t I 1 5

' Sincerely,

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s /s/7 M. David Lynch, Senior Project Manager Project Directorate III-2

, ,.' Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation ,

Docket Nos. STN 50-454, STN 50-456

Enclosure:

Request for Additional Information cc w/ enc 1: see next page Distribution: . .

J. Roe, JWR Docket File E. Adensam, EGA1 PUBLIC  ;

R. Capra PDIII-2 r/f C. Moore OGC, ul5B18 D. Lynch ACRS, T2E26

G. Dick R. Lanksbury, RIII R. Assa i S. Coffin, 07D4 P. Rush, 07D4 i E. Sullivan, 07D4 D. Diec, 08E23

T. Collins, 08E23 K. Wichman, 07D4 J. Strosnider, 0704 D.-Diec, 08E23 Document Name: G:\CMNTJR\ BRAID-BY\BBVOLT.RAI

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• RCAPRA 9.* i DATE 6/ /f_7/97 / /c7//97, 1/23/96 o//2 8 /97

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I. Johnson Byron /Braidwood Power Stations Consonwealth Edison Company cc: r Mr. William P. Poirier, Director George L. Edgar Westinghouse Electric Corporation Morgan, Lewis and Bochius Energy Systems Business Unit 1800 M Street, N.W.

Post Office Box 355, Bay 236 West Washington, DC 20036 Pittsburgh, Pennsylvania 15230 Attorney General Joseph Gallo 500 South Second Street

• Gallo & Ross Springfield, Illinois 62701 1250 Eye St., N.W.

Suite 302 EIS Review Coordinator Washington, DC 20005 U.S. Environmental Protection Agency 77 W. Jackson Blvd.

Michael I. 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. Learner 1035 Outer Park Drive Environmental law 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, Illinois 61010  ;

U.S. Nuclear Regulatory Commission Byron Resident 1sspectors 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 III Byron, Illinois 61010

U.S. Nuclear Regulatory Commission i

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

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Rural Route #1, Box 79 Ms. Lorraine Creek Braceville, Illinois 60407 Rt. 1, Box 182 Manteno, Illinois 60950 Mr. Ron Stephens

Illinois 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 l

, Joliet, Illinois 60434 4

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Commonwealth Edison Company Braidwood Station Manager Rt. 1, Box 84 Braceville, Illinois 60407 Ms. Bridget Little Rorem Appleseed Coordinator 117 North Linden Street Essex, Illinois 60935 Document Control Desk-Licensing Commonwealth Edison Company 1400 Opus Place, Suite 400

-Downers Grove, Illinois 60515 Mr. H. G. Stanley Site Vice President Braidwood Station Commonwealth Edison Company RR 1, Box 84 Braceville, IL 60407 1

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l RE0 VEST FOR ADDITIONAL INFORMATION M LATED TO THE EXTENSION OF THE 3.0 V0LT LOWER V0LTAGE REPAIR LIMIT FOR ODSCC BYRON UNIT 1 AND BRAIDWOOD UNIT _1 DOCKET NOS. STN 50-454 AND STN 50-456 l 1. Provide a summary of the results from the inspection of the steam j generator (SG) internal structures conducted in the Byron 1 outage in October 1995, similar to the summaries provided.in the two reports cited in the references below.

2. The licensee stated in Reference 1 that it visually inspected 89 vertical support bars and 157 vertical support bar welds in the four SGs and found no indication of structural degradation in the welds which would prevent the support bars from performing their function. State whether any types of indications were found. If so, describe the nature of these indications, including the number of such indications and their l

location and an evaluation of their potential effect on the structural capability of the vertical support bar welds.

3. In Reference 1, the licensee stated that it inspected 50 tubes around each of the three antirotation devices and did not find any i operationally-induced degradation of the tube support plates (TSPs).

State whether any type of degradation was found. If so, describe the nature of the degradation, including the extent, the location, the probable cause and an evaluation of the effect on the stiactural capability of the TSPs.

4. In its letter dated August 19, 1996, the licensee stated that it will use a modified eddy current inspection (ECI) technique to inspect 50 tubes adjacent to each antirotation device in all four SGs and to  ;

inspect 20 tubes along the patch plate scam in one SG. State when and where this inspection will be performed (e.g., during the upcoming refueling outages at Braidwood I and Byron 1).

5. State whether the presence of the TSP intersections will continue to be verified during SG ECIs.

6. In its letter dated August 19, 1996, the licensee stated that it will verify the integrity of the SG tube expansions at the TSP intersections for the 21 SG tubes used to stabilize the TSPs by inspecting 20 percent of these expansions. Additionally, this sample of SG tubes will also be inspected at the top of the tubesheet in the roll transition zone.

State when and where this SG tube inspection will be performed (e.g.,

during the upcoming refueling outages at Braidwood 1 and Byron 1).

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Describe the criteria for selecting the initial inspection sample of SG tubes.

7. In its submittal dated August 19, 1996, the licensee also stated that the staff will not be notified if axial indications are detected at the sleeved and expanded joint intersection of the 21 SG tubes with the TSPs or at the TTS. Since these SG tubes were inspected before plugging and no indications were found, the staff requests that it be promptly notified if any type of indication is found in subsequent inspections of these locations.

8. The licensee stated in its August 19, 1996 submittal, that it will continue to implement the criteria for eddy current probe wear recommended by the Nuclear Energy Institute (NEI). This approach requires that all indications greater than 75 percent of the lower voltage repair limit which were inspected with a worn probe, be reinspected with a new probe. State whether Braidwood I and Byron I will continue to reinspect with a new probe after determining that significant probe wear exists, indications greater than 75 percent of 1.0 volt, even at hot-leg intersections at which the 3.0 volt alternate repair criteria (ARC) is applied.

9. In its submittal dated August 19, 1996, the licensee stated that the probability of axial tensile failure will be calculated in accordance with the guidance in Generic Letter (GL) 95-05 and will combine this probability with the conditional probability of axial burst failure if any indications with a voltage greater than or equal to 15 volts are identifieci or if a large number of iadications between ten and fifteen volts are identified. State the basis for specifying a limit of  !

l 15 volts. Indicate why there is an upper limit on this range. Define '

what constitutes a large number of indications, including the basis for this criterion.

! 10. The licensee proposed to add definitions of both the Locked TSP Model 2

and the Freespan Model into the Byron 1 and Braidwood 1 TSs. However, the staff review of the definitions proposed to be added to TS Section 4.4.5.4.a indicates that intersections containing a corrosion-induced dent greater than 0.065 inches are not excluded. Provide a basis for this approach.

11. Provide the scheduled date for the start of the Braidwood 1 Cycle 6

, refueling outage and the Byron 1 Cycle 8 refueling outage.

12. During a SG blowdown following a postulated main steamline break (MSLB),

the pressure drop across a TSP will be determined by the position dependent flow distribution across a TSP. Because of the difference in resistances between fluid flows parallel and perpendicular to the SG tube bundles above the topmost TSP, a multidis..nsional flow pattern

exists. This effect will be most pronounced at the upper TSP.

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i Accordingly, assess the effect of the multidimensional flow pattern on the position dependent pressure drop across the TSPs.

References

1. Comed letter dated March 5, 1996, "r- Good Station Unit 1 Steam Generator Interim Plugging Criteria is Day Report".

2. Comed letter dated September 9,1996, " Byron Station Unit 1 Steam Generator Interim Plugging Criteria 90 Day Report for the End-of-Cycle 7 Inspection".

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