ML20149M313

Summary of 961114 Meeting W/Representives of CE in Rockville,Md to Discuss Status of Ongoing Braidwood,Unit 1, SG Tube Insp.List of Attendees & Slides Encl

ML20149M313
Person / Time
Site:	Byron, Braidwood
Issue date:	12/10/1996
From:	Lynch M NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9612160108
Download: ML20149M313 (35)

Text

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UNITED STATES

-h NUCLEAR REGULATORY COMMISSION 4

f WASHINGTON, D.C. seeH001 k  ! December 10, 1996 LICENSEE: CO MONWEALTH EDISON COMPANY FACILITIES: BRAIDWOOD, UNIT 1, AND BYRON, UNIT 1

SUBJECT:

SUM ARY OF A MEETING WITH THE CO MONWEALTH EDISON COMPANY ON I NOVEMBER 14, 1996, REGARDING THE STATUS OF THE ONGOING BRAIDWOOD, UNIT 1, STEAM GENERATOR TUBE INSPECTION i

A meeting was held on November 14, 1996, in Rockville, Maryland, between representatives of the Commonwealth Edison Company (Comed) and the NRC staff.

The purpose of the meeting was to discuss the status of the ongoing Braidwood,

' Unit 1, steam generator (SG) tube inspection as well as the repair program. A list of attendees is provided in Enclosure 1. A copy of the slides presented at this meeting is provided in Enclorure 2.

The present SG tube inspection at Braidwood, Unit 1, was initiated on October 11, 1996, and was conducted to determine whether there were i circumferential indications at the top of the tubesheet (TTS) in the roll transition zone. The staff had previously taken the position in a letter dated May 22, 1996, that Braidwood, Unit 1, could operate until October 15, 1996, following restart of this unit after its fall 1995 refueling outage, before conducting an eddy current inspection (ECI) of the SG tubes at the TTS.

' This position was based on the results of the inspection program conducted in the last outage. This position also reflected the staff's concerns related to the large number of SG tubes at Byron, Unit 1, which had circumferential i indications at the TTS. Both Byron, Unit 1, and Braidwood, Unit 1, have

Westinghouse Model D4 SGs; the Byron, Unit 1, SGs have been in service for two more fuel cycles than those of Braidwood, Unit 1.

Comed stated in the subject meeting that it had completed a 100 percent ECI of

all SG tubes in the hot leg side of all four SGs using the plus point probe.

! All of the 1436 SG tubes with circumferential, axial and mixed mode indications found in this latest Braidwood, Unit 1, ECI have been repaired 1

either by plugging or by inserting Westinghouse laser-welded sleeves.

A total of 23 SG tubes in the "A" and "B" SGs having the largest measured

! voltages were subjected to two sets of in-situ pressure tests to determine I\

their leak-tightness under postulated accident conditions; i.e., a postulated \

main steam line break (MSLB). Four of the first ten SG tubes pressure tested leaked; Comed estimated that two of these four SG tubes which leaked would have had very small leakage at MSLB conditions. For one of these four SG M,Oq\

tubes, Row 22 Column 73 in the "B" SG (R22/C73 B), the initial measured in-situ leakage was 0.5 gallons per minute (gps) at a differential test pressure of 1300 pounds per squsre inch (psid). The limited capacity of the pump which was used in the first set of tests did not allow a higher test pressure to be

achieved. Subsequently, a test pressure of 2300 psid was achieved in the second set of in-situ pressure tests using a higher capacity pump resulting in

, a measured leak rate of 1.0 gpm for tube R22/C73 B. Correcting for the 961216010s 961210 PDR ADOCK 05000454 -

0 PDR g -

130051

4 i

i 1

l effects of temperature and pressure, Comed estimated the potential leak rate j

for this tube under MSLB conditions for the first pressure test to be 2.1 gpm based on extrapolating the initial test data and 1.0 gpa from the data for the 4

second set of leak tests. Comed has conservatively assumed that the leakage l under MSLB conditions for this particular SG tube is 2.1 gps.

1 1

In light of the results of the first ten SG tubes pressure tested, Comed pressure tested another 13 tubes from SGs "A" and "B." Only one of these SG tubes in the second set leaked. Of the five SG tubes that leaked, Comed estimated that prior to the Braidwood, Unit 1, shutdown in mid-October 1996, the total potential leakage under MSLB conditions would have been 2.15 gpm from SG "B"; i.e, 2.1 gpa from R22/C73 8 and 0.05 gpa from R21/076 B.

All of the first ten SG tubes pressure tested were subsequently tested for structural integrity at a differential test pressure of 5100 psid; none of these burst. None of the second set of 13 SG tubes were tested for burst strength because the first set of SG tubes which were pressure tested for leakage were considered by Comed to be the most likely candidates to burst.

On the basis of the' foregoing discussion, Comed concluded that the structural integrity requirements for the Braidwood, Unit 1, SG tubes were satisfied during the operating time of about ten months ending in fall 1996. Comed also concluded that the potential leak rates under MSLB conditions for the worst SG were lower than the Braidwood Station site allowable leakage rate of about 27 gps. With respect to the restart of Braidwood, Unit 1, Comed stated that the Braidwood, Unit 1, SGs could be safely operated for an additional five months and based this conclusion on its evaluation of the data obtained in the present mid-cycle SG ECI and the results of the in-situ pressure tests.

During the visual inspection of the Braidwood, Unit 1, SGs, there appeared to be a potential leak past a plug in one of the 21 SG tubes which had been expanded into the tube support plates (TSPs), thereby making it function as an ,

additional tie rod limiting the displacement of the TSPs under postulated '

accident conditions. These additional tie rods in the Byron, Unit 1, and Braidwood, Unit 1, SGs were a crucial element in the 3.0 volt alternate repair criteria (ARC) license amendments issued in fall 1995 for Byron, Unit 1, and i Braidwood, Unit 1. Comed stated that it had removed this plug and conducted '

an ECI of this subject tube; no defects in the tube were detected.

With respect to the pending request to delete a mid-cycle ECI in the present I fuel cycle for Byron, Unit 1, Comed stated that it would submit all of its '

responses to the prior requests for additional information (RAls) by November i 27, 1996. However, Comed was e.ot ready at this meeting to discuss the i methodology it will propose ror estimating the end of cycle (EOC) leakage rates under MSLB conditions. Comed stated that its approach for estimating .

EOC leakage will be presented in its November 27, 1996, submittal. l Accordingly, whereas Comed had previously requested a staff decision by the end of Novemberfl996 regarding its proposal to operate the Byron, Unit 1, SGs for 600 days without a mid-cycle ECI until their replacement in early 1998, Comed now requested that the staff provide its decision on the pending proposal by mid-January 1997. This delay will allow the results of the  ;

present Braidwood, Unit 1, SG inspection, including the preliminary results of l

i 1

the metallurgical examination of the four SG tubes pulled from one of the Braidwood, Unit 1, SGs, to be factored into Comed's submittal on November 27, 1996. ,

~

f At the end of the meeting, the staff provided a number of comments as follows:

1. Comed had significantly expanded the database characterizing )

circumferential indications at the'TTS in Westinghouse Model:D4 SGs.

2. The staff noted that Comed's approach for determining leakage presented during the meeting is inconsistent with that used previously in Comed's

cycle length assessment. Accordingly, the-staff requested Comed to consider analyzing the potential leakage for a ' postulated MSLB using a

probability of leakage correlation incorporating all available industry

, data, including that obtained in the present Braidwood, Unit 1, i inspection. The staff requested that this leakage evaluation be included in the forthcoming submittal on November 27, 1996.

j 3. The satisfactory inspection results of the SG tube expanded as part of the 3.0 volt ARC amendments issued in fall 1995 for both Byron, Unit 1, and ,

Braidwood, Unit 1, provides assurance that the basis for the staff's

acceptance of the 3.0 volt ARC license amendments is not affected by the results of this mid-cycle Braidwood, Unit 1, SG inspection.

4

4. The staff believes that one of the main issues related to the length of operating cycle between SG tube inspections at Byron, Unit 1, and Braidwood, Unit 1, continues to be an appropriate method for estimating

the potential leakage at the end of the inspection interval under MSLB >

conditions.

1

5. Finally, the staff requested that the revised methodology for estimating

leakage at the end of the inspection cycle be benchmarked by applying the circumferential indication growth rate observed in the most recent Byron, ,

Unit 1, fuel cycles to the beginning of cycle (B0C) Braidwood, Unit 1, circumferential indications.

/s/

M. D. 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 l

! I

Enclosures:

i 1. List of Attendees )

2. Slides '

cc w/encls: See next page DOCUMENT NAME: LYNCH \ll14.MTS c, Indioety in the box: "C" = Copy without enclosures *E" = Copy with enclosures *N" = No copy i

To receive a copy of this f::- -

0FFICE ph9DM-ft LA1PIflII-2 (' D:PDIII-2 l E.

NAME N/ OMdWE RCAPRA P DATE 12'/dt/96 %

12/(9/96 12/ro/96 0FFICIAL RECORD COPY

._. - .- _ _ . - - _ - _ _ = .

i

. I Byron /Braidwood Power Stations cc:

Ms. I. Johnson Mrs. Phillip B. Johnson Acting Manager, Nuclear Regulatory Services 1907 Stratford Lane Comonwealth Edison Company Rockford, Illinois 61107 Executive Towers West III 1400 Opus Place, Suite 500 George L. Edgar Downers Grove, Illinois 60515 Morgan, Lewis and Bochius 1800 M Street, N.W.

Mr. William P. Poirier, Director Washington, DC 20036 Westinghouse Electric Corporation Energy Systems Business Unit Ms. Bridget Little Rorem Post Office Box 355, Bay 236 West Appleseed Coordinator Pittsburgh, Pennsylvania 15230 117 North Linden Street Essex, Illinois 60935 Joseph Gallo Gallo & Ross Attorney General l 1250 Eye St., N.W. 500 South Second Street i Suite 302 Springfield, Illinois 62701 Washington, DC 20005 I EIS Review Coordinator Michael I. Miller, Esquire U.S. Environmental Protection Agency i Sidley and Austin 77 W. Jackson Blvd.

One First National Plaza Chicago, Illinois 60604-3590 Chicago, Illinois 60603 Illinois Department of Howard A. Learner Nuclear Safety Environmental law and Policy Office of Nuclear Facility Safety ,

Center of the Midwest 1035 Outer Park Drive i 203 North LaSalle Street Springfield, Illinois 62704 Suite 1390 Chicago, Illinois 60601 Commonwealth Edison Company Byron Station Manager U.S. Nuclear Regulatory Comission 4450 North German Church Road Byron Resident Inspectors Office Byron, Illinois 61010 4448 North German Church Road Byron, Illinois 61010-9750 Kenneth Graesser, Site Vice President Byron Station Regional Administrator, Region III Comonwealth Edison Station U.S. Nuclear Regulatory Comission 4450 N. German Church Road 801 Warrenville Road Byron, Illinois 61010 Lisle, Illinois 60532-4351 U.S. Nuclear Regulatory Comission Ms. Lorraine Creek Braidwood Resident Inspectors Office Rt. 1, Box 182 Rural Route #1, Box 79 Manteno, Illinois 60950 Braceville, Illinois 60407 Chairman, Ogle County Board Mr. Ron Stephens Post Office Box 357 Illinois Emergency Services Oregon, Illinois 61061 and Disaster Agency 110 East Adams Street ,

Springfield, Illinois 62706

Chairman Will County Board of Supervisors Will County Board Courthouse Joliet, Illinois 60434 '

Commonwealth Edison Company Braidwood Station Manager Rt. 1, Box 84 Braceville, Illinois 60407 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 Bracemille, IL 60407 l

_. _ . _ _ _ _ ._. ~ . - - - - -- - - --

l

.i l

COMONWEALTH EDISON COMPANY

SUBJECT:

SUMARY OF A MEETING WITH THE COMONWEALTH EDISON COMPANY ON MOVEMBER 14, 1.996 l

l Distribution:

Hard Cony w/encls I and 2 w/ encl 1 only: '

Docket File OGC PUBLIC ACRS PDIII-r/f MDLynch RLanksbury, RIII E-Mail w/ encl 1 only:

JRoe JWR RZimmerman RPZ FMiraglia FJM EAdensas EGAl ,

RCapra RACI GDick RAssa CMoore ACM EJordan ELJ1 BMcCabe BCM JStrosnider KWichman WKropp Philip Rush Ted Sullivan Glainas Stephanie Coffin

)

l l

1 MEETING ATTENDANCE 4

November 14 1221 NAng Affiliation Eh2at l M. D. Lynch NRR/PDIII-2 415-3023 George Dick NRR/PDIII-2 415-3019 Ramin Assa NRR/PDIII-2 415-1391

Jack Strosnider NRR/DE 415-2796 Gus Lainas NRR/DE 415-3298 Stephanie Coffin NRR/EMCB (301)415-2778 Keith Wichman NRR/ENCB 415-2757 i

Philip Rush NRR/EMCB 415-2790 Ted Sullivan NRR/EMCB 415-3266

. Wayne Kropp RIII/EB Branch Chief 829-9633 i

John Hosman Comed Engineering (703)663-7344 Roman Gestor Comed Engineering (630)663-7671 John Blomgren Comed Engineering (630)663-7215

David Wozniak Comed / Byron Station (815)234-5441 X2612 James Meister Comed /Braidwood Station (815)458-2801 X2341

, Denise Saccamondo Comed /NLA (630)633-7283 Ron Gamble Sartrex (301)468-6403 Jim Begley AP Tech (412)920-6633 4

i f

ENCLOSURE 1

, i Comed /NRC Steam Generator Status Meeting Braidwood Unit 1 November 14,1996 ENCLOSURE 2

Agenda

. Introduction J hn Blomgren

- Meeting Objectives

- Braidwood 1 Plan

- Byron /Braidwood 1 Strategy

- Braidwood Tube Pull Plan Roman Gesior

- Braidwood 1 Status .

- Inspection and Repair Overview

- Structural Assessment

- Leakage Assessment

- Locked Tube Inspection Conclusions . -

John Blomgren  :

~

Meeting Objectives Inform NRC Regarding the Results of Braidwood 1 Inspection Demonstrate Braidwood 1 Met Steam Generator Tube-Integrity Requirements Define the Strategy for Cycle Length Assessment for '

^

Byron and Braidwood Unit 1 i

I i

l l

Braidwood 1 Plan P

100% HL TTS + Point Probe Inspection of 4 SG's  !

Repaired all Circumferential Indications Insitu Pressure Tested Largest Indications

\

Pull Tubes with Circumferential Indications  ;

R~un to Spring 1997 Refuel Outage Perform 100% HL & CL TTS + Point Inspection in Refuel

Conclusions In Situ Pressure Test Results of the Braidwood 1 Circumferential Indications t Present for Over 496 Days Confirm Tube Integrity Requirements Maintained In Situ Tests of Circumferential Indications Which Grew Since 2/95 Did Not Leak

i Byron /Braidwood Strategy Revise POL Curve with Insitu Data and Revised Voltage Adjustment Factors Recompute Leak Rate for Projected EOC Distribution with Insitu Leak Data i

Revise Burst Curve Based on Non-Burst Bound, Insitu Pressure Test Data, and Revised Voltage Adjustment  ;

Factors Recompute Structural Limit Based on Revised Burst Curve Analyze Pulled Tubes Perform Byron and Braidwood Cycle Length Assessment  !

i

____.______________________._______________________________________._-.___________i

Byron Strategy

- Schedule

- RAI Response - 11/27/96 i

- Meeting on RAI Response - Mid-December t

- Preliminary Tube Pull Results - Mid-December

- NRC Cycle Length Review Completion - Mid-January i

l i

i i

Braidwood 1 Tube Pull Plan Pull 4 Tubes

- Largest Voltage Indication

- Largest Leak Indication

- Smaller Indication No Leakage

- Indication with Large Max. Voltage Low Avg. Voltage Metallographic Analyses to Assess:

- Morphology

- Percent Degraded Area and 100% TW Area

- Similar Analyses as Byron 1 Tube Pulls

- Burst Testing of Flaws

- Assess Voltage Sizing Techniques

Braidwood 1 Status Inspection and Repair Overview i

Inspection Scope

- 100% HL TTS

- + Point Probe (+ Point,0.080" & 0.115" RPC)

- EddyNet95 Analysis Software Voltage Screening Identified the Degradation in SG D to be Significantly Lower than in the Remaining 3 SG's Insitu Pressure Test 23 Circumferential Indications Pull 4 SG Tubes .

Sleeve or Plug all Circumferential and Axial Indications, Stabilize Circumferential Indications l

i

i i

l Braidwood 1 A1P02 Inspection / Repair Overview

\

Number of Tubes With Indications

. Indication 1 A SG 1B SG 1C SG 1D SG Total l Circumferential 221 276 610 293 1400 Axial 1 20 3 8 32 Mixed Mode 2 3 6 3 14 Total 224 299 619 304 1446

! Total Repairable Tubes

• 224 295 618 299 1436

' Tubes Sleeved 181 0 443 272 detP- Sg Tubes Plugged and Stabilized Total Equivalent Plugging %

43 295 17R 27 191>- Q 13.2 9.3 20.6 9.6 13.2

• Some tubes have more than 1 Indication l l

i i

6 O

Braidwood 1 Assessment Burst:

5 of the Largest Indications in SG A and 5 in SG B Insitu Pressure Tested to 5000 psi All Tubes Satisfied Structural Integrity Requirements 9 of 10 Indications Present in Look-Back to 2/95 Period of Time from 2/95 to 10/96 is 496.5 Days > 500oF Significantly Improved Inspection Techniques in 10/96 Therefore Structural Integrity Requirements for Braidwood 1 Steam Generator Tubes are Met

i Braidwood 1 Assessment ,

t Leak:

7 of the Largest Indications in SG A and 16 of the Largest Indications in SG B were Insitu Leak Tested to 3100 psi 1

Total Circumferential Indication Leakage from Limiting SG is 2.15 gpm (SG B) 17 of the 23 Indications were Present in Look-back to 2/95 Period of Time from 2/95 to 10/96 is 496.5 Days > 500oF All the Indications which Leaked were Present in 2/95 Significantly Improved Inspection Techniques in 10/96 Therefore Site Allowable Leak Rates for Braidwood 1 Steam Generator Tubes are Met

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Frequency Distribution for Average 0.080' Coil Voltage .

0.35 A

0.30  ;. - - * - -SG C # of inds m -

. --o-SG B # of Inds Less # insitu Tested C . * *

$= 0.25 -

I -

' a SG B # Insitu Tested

.2 -

! 5 x SG A # insitu Tested

]  :  ! 1 -

= -

U0 0.20 -

x  ; . _ No E -

' Leak C.

• 0.15 o -

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e  : 5

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0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 Average 0.080" Coil Voltage, Volts

Conclusion:

Insitu Pressure Tested Indications in SGs A and B Bound Largest Indications at Braidwood 1

l Frequency Distribution for Maximum 0.080" Coil Voltage 0.35 .

.' SG C # of In6s

-o--SG B # of Inds Less # Iresilu Tested 4

a SG B # Insitu Tested I

e -

.- x SG A # insitu Tested o '. t li 0.25

.2 - I i

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= -

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4 0.05 g g A ) .

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--- " # # b '"* ' ' ' ' ' ' ' ' ' '" ' ' ' '

O.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Maximum 0.080" Coil Voltage, Volts

Conclusion:

Insitu Pressure Tested Indications in SGs A and B Bound Largest Indications at Braidwood 1 sooouvens

Braidwood 1 Structural Assessment Maximum and Average Voltage are used to Assess Structural Integrity 5 of the Largest Indications in SG A and 5 in SG B Insitu Pressure Tested to 5000 psi, 3xNOdP 4035 psi SG's A & B Have the Largest Indications, Bound SG's C & D Tube Selection Based upon Arc Length, + Point and 0.080" RPC Avg. Voltages

- Arc Lengths Range from 164 to 316 Degrees

- + Point Avg. Voltages Range from 0.35 to 2.25 Volts

- 0.080" RPC Avg . Voltages Range from 0.29 to 1.2 Volts Tubes Met Structural Integrity Requirements i

Braidwood 1 Leakage Assessment 7 Indications in SG A and 16 in SG B Leak Tested at 3100 psi, MSLB Pressure is 2560 psi Tube Selection Based Upon + Point and 0.080" RPC Vert.

Max. Voltages and Max. Depth (Phase Angle)

- + Point Vert. Max. Voltages Range from 0.65 to 7.07 Volts

- 0.080" Vert. Max. Voltages Range from 0.39 to 3.5 Volts

- + Point Max Depths Range from 8% to 88%

Total Leakage in Limiting Steam Generator 2.15 gpm < Site Allowable Leak Limit (26.8 gpm) when Combined with Predicted TSP ODSCC Leakage (6.99 gpm) and Leakage from Unfaulted SG's

Braidwood Unit 1 insitu Test ResuR ,

Test Leak Pressure MSLB Leak ROW COL .080 MAX Rate (gpm) (psi) Rate (gpm)

SG B 21 76 3.5 0.1 3200 0.046 22 73 1.49 0.5 1300 2.1 t 22 73 1.49 1 2300 1 .

SG A -

27 60 1.14 0.006 5100 0 27 55 1.7 0.001 3200 0 23 41 1.43 0.001 3100 0 No Indications Below 0.080' Max. Voltage Leakage Threshold of 1.29 volts Leaked at MSLB Conditions  ;

Teial Leak Rate from Limiting SG = 2.15 gpm at MSLB Conditions

Braidwood 1 Tube R22C73 MSLB Leak Rate Confirmation  ;

ABB Insitu Test System Could not Attain MSLB Pressures due to High Leak Rates During Insitu Testing Westinghouse High Capacity Pump Mated with ABB Insitu Test System System Developed to Provide Confirmation of Calculated Leak Rates for Tube R22C73 at MSLB Conditions Due to Significant Pressure Drop in Test System (3000 -

4000 psi) System Flow Capacity is Reduced Qualification Testing of System to Verify the Pressure at the Flaw .

i

Braidwood 1 Tube R22C73 MSLB Leak Rate Confirmation Leak Rate for Tube R22C73 Using the Hybrid System was '

1 gpm at a Flaw Pressure of 2300 psi Corrected to MSLB Conditions the Leak Rate is 1 gpm

Conclusion:

This Result Confirms the Magnitude of the Leak Rate (1 -2 gpm) Determined by Calculational Methods for R22C73 at MSLB Conditions i

i i

f

~

t i

Locked Tube Inspection A Wet Plug was Identified in Visual Inspection of SG A

- The Plug was in a Tube Expanded for TSP ODSCC IPC

- The Plug was Removed

- No Water in Tube Inspection Scope:

- From Tube End to 7th Support Plate Inspected with 610 Bobbin

- TTS Inspected with Three Coil + Point Probe

- 4 Locked TSP Expansions (8,9,10, & 11) Inspected with Gimbated

+ Point Probe Primary, Secondary and Resolution Analysis with Independent Review of 2 Level III's No Indications Detected

Conclusion:

Plug Did Not Leak i

. ..l Braidwood 1 Plan 100% HL TTS + Point Probe Inspection of 4 SG's Repaired all Circumferential Indications Insitu Pressure Tested Largest Indications Pull Tubes with Circumferential Indications Run to Spring 1997 gpgel Outage Perform 100% HL &g CL TTS + Point Inspection in Refuel

Byron /Braidwood Strategy Revise POL Curve with Insitu Data and Revised Voltage Adjustment Factors ,

Recompute Leak Rate for Projected EOC Distribution with Insitu Leak Data Revise Burst Curve Based on Non-Burst Bound, Insitu Pressure Test Data, and Revised Voltage Adjustment .

Factors Recompute Structural Limit Based on Revised Burst Curve -

Analyze Pulled Tubes Perform Byron and Brhidwood Cycle Length Assessment

i Byron /Braidwood Strategy

- Schedule

- RAI Response - 11/27/96

- Meeting on RAI Response - Mid-December

- Preliminary Tube Pull Results - Mid-December

- NRC Cycle Length Review Completion - Mid-January

Conclusions In Situ Pressure Test Results of the l Braidwood 1 CircumferentialIndications Present for Over 496 Days Confirm Tube Integrity Requirements Maintained In Situ Tests of Circumferential Indications Which Grew Since 2/95 Did Not Leak

worst SG freq vs EOC approach  ? .*

i I

Braldwood 1 SG B Frequency vs. Projected Frequency (EOC Approach) 0.25 r W LaakiInes:

SG B Ti:-- -_ i Conoceed to Toid Number Projected (EOC Naproach) m -5.3 spm -- / 7

~

800 0.2 m a r-- - c nime- - wm  :

gg Indicatons - 11 B gpm Burst ." .-..:(SG B as Actad):

D Inesynes Tag or Diselbudon(EOC W):

• ""-*' E 0.15 u -

o@Mual 2 Tubes -ameles 3 Tubes - 2.60 iolts Inespets Tag of DIsetuton(SG Ii Aceuel)

RA D 1 Tube - 3.5 voin 0.1 U ' -# -i 3 Tubes - 1.6 wan'

, f 0.05

~li.s '

a U

, i 0- ,N N' N N' O.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.000" RPC VoRage, volts AM Page1

c ..

ave volts freq. ch Breldwood 1 SG B Frequency vs. Projected Frequency (EOC Approach) Avg Volts 0.3 Bu st Assessment (SG B as Acaual): -

0.25 ,,i, uy== Tad or L- ivutwni p:vu aw v cie):

11ube - 1.80 volts 27ubes =1.50 voks 0.2 3 Tubes = 1.35 volts Intigrate Tail of Distributen (SG B Actual):

a 11ube = 1.2 volts 0.15 2 *" '

{ 31ubes = 0.65 volts 0.1 =

a y ql

. PCX 0.05

y B

0 . -<

0 0.5 1 1.5 2 2.5 0.000" RPC Average Voltage, volts Page1 .

_____....___.___-_____._.___.-__m.. _ . . _ . _ _ _ _ . _ . _ . - _ _ . _ . _ . . _ . _ _ . . _ _ _ _ _ _ _ . _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ __s _ _ _ _ _

?

v' the metallurgical examination of the four SG tubes pulled from one of the Braidwood, Unit 1, SGs, to be factored into Comed's submittal on November 27, 1996.

At the end of the meeting, the staff provided a number of coments as follows:

1. Comed had significantly expanded the database characterizing circumferential indications at the TTS in Westinghouse Model D4 SGs.

1

2. The staff noted that Coned's approach for determining leakage presented  !

during the meeting is inconsistent with that used previously in Comed's '

cycle length assessment. Accordingly, the staff requested Comed to consider analyzing the potential leakage for a postulated MSLB using a probability of leakage correlation incorporating all available industry data, including that obtained in the present Braidwood, Unit 1, inspection. The staff requested that this leakage evaluation be included in the forthcoming submittal on November 27, 1996.

3. The satisfactory inspection results of the SG tube expanded as part of the 3.0 volt ARC amendments issued in fall 1995 for both Byron, Unit 1, and  !

Braidwood, Unit 1, provides assurance that the basis for the staff's acceptance of the 3.0 volt ARC license amendments is not affected by the results of this mid-cycle Braidwood, Unit 1, SG inspection.

2 4. The staff believes that one of the main issues related to the length of operating cycle between SG tube inspections at Byron, Unit 1, and Braidwood, Unit 1, continues to be an appropriate method for estimating the potential leakage at the end of the inspection interval under MSLB conditions.

5. Finally, the staff requested that the revised methodology for estimating leakage at the end of the inspection cycle be benchmarked by applying the circumferential indication growth rate observed in the most recent Byron, Unit 1, fuel cycles to the beginning of cycle (B0C) Braidwood, Unit 1, circumferential indications.

^

en O M. D. 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

Enclosures:

1. List of Attendees

2. Slides cc w/encls: See next page