ML20141F364

Summary of 970430 Meeting W/Licensee in Rockville,Md to Discuss Various Aspects of SG Eddy Current Insp Conducted at Plants During Spring 1997 Refueling Outage.List of Attendees & Licensee Handouts Encl

ML20141F364
Person / Time
Site:	Byron, Braidwood
Issue date:	06/27/1997
From:	Lynch M NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
TAC-M96498, TAC-M96500, NUDOCS 9707020281
Download: ML20141F364 (36)

Text

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g j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20e86-0001 o% *****/ June 27, 1997 LICENSEE: Commonwealth Edison Company (Comed)

FACILITIES: Braidwood Station, Unit 1 Byron Station, Unit 1

SUMMARY

OF MEETING CONCERNING THE STEAM GENERATOR INSPECTION RESULTS AT BRAIDWOOD, UNIT 1 AND ITS IMPLICATION FOR BYRON, UNIT 1 (TAC NOS. M96498 AND M96500) l A meeting was held on April 30, 1997, in Rockville, Maryland, between members of the NRC staff and representatives of the Commonwealth Edison Company (Comed, the licensee). The purpose of the meeting was to discuss various aspects of the steam generator (SG) eddy current inspection (ECI) conducted at Braidwood, Unit 1, during the spring 1997 refueling outage (i.e., the end-of-cycle 6 (E0C-6)). The discussion also briefly touched upon the potential implications for Byron, Unit 1, in light of the recent Braidwood, Unit 1, ECI.

A list of attendees is provided as Enclosure 1. A copy of the licensee's slides is provided as Enclosure 2.

In November 1995, Comed implemented a 3.0 volt interim plugging criteria (IPC) in the Braidwood, Unit 1, SG in accordance with License Amendment No. 69, dated November 9, 1995. This license amendment revised the Braidwood, Unit 1, Technical Specifications (TS) to incorporate the 3.0 volt IPC, cited above, in place of the prior 1.0 volt IPC first authorized in 1994. This earlier, more restrictive IPC was generally consistent with the methodology endorsed by the staff in Generic Letter (GL) 95-05. The methodology in GL 95-05 endorses the use of a freespan model for the repair criteria for SG tubes subject to primarily axially oriented outer diameter stress corrosion cracking (ODSCC) at the intersection of the SG tubes with the tube support plates (TSP). The methodology in the 3.0 volt IPC is identified as the locked tube model which takes credit for certain SG hardware modifications implemented during the Braidwood,' Unit 1, fall 1995 refueling outage. The main hardware modification was to expand (lock) 21 SG tubes per SG for a total of 85 locked SG tubes, into selected regions of the TSPs at various SG elevations and thereby act as additional stay rods. Comed had demonstrated, through analysis and testing ir, 1995, that adding these additional locked SG tubes limited the deflection of the TSPs under postulated accident conditions to a relatively small value (i.e., less than 0.100 inches). The net effect of this effort was to significantly reduce the conditional probability of burst of the SG tubes left in service using the 3.0 volt IPC; the potential leakage from these SG tubes was also reduced.

The issue which led to the April 30, P97, meeting was the pending Comed request for a Braidwood, Unit 1, license amendment to extend the 3.0 volt IPC for one more operating cycle. Implementation of the 3.0 volt IPC had been limited to one cycle (i.e., from fall 1995 to spring 1997).

NBC Fil.E CElFEB COPY 9707020281 970627 -

PDR ADOCK 05000454 G PDR _

1

! i At this meeting, Comed compared the predictions for EOC-6 for main steamline 4 break (MSLB) leakage made at the previous outage (i.e., fall 1995) with a leakage calculation based on the actual EOC-6 ECI results. Although still

well under the Braidwood, Unit 1, site allowable leakage limit, the MSLB

! calculated leakage using E00-6 data was substantially higher than the MSLB

! leakage using projected E00-6 voltages. The licensee attributed this f phenomenon to an under prediction of the size and number of large 00 SCC indications (i.e., greater than 5 volts). Comed is attempting to determine.

the cause of this under prediction and will address its resolution in its 90 Day Report. The licensee will also reexamine the E0C-8 predictions for Byron, Unit 1, since the methodology applied for this unit was the same as used for Braidwood 1. Byron, Unit 1, had also implemented a 3.0 volt IPC in its fall 1995 outage. Preliminary calculations for Braidwood, Unit 1, MSLB leakage at E0C-7 (i.e., fall 1998) indicates a need for a reduction in the dose equivalent iodine level to justify a full cycle of operation.

Comed inspected all the Braidwood, Unit 1, " locked" tubes. Forty-nine of the 85 expanded SG tubes had circumferential indications in the top-of-the-tubesheet (TTS) region. The licensee pressure tested the seven largest indications to 3200 psi; no leakage was detected. The largest indication was pressure tested to 4900 psi with no leakage. With these test results, Comed concluded that the degraded locked tubes had significantly more load carrying capability than required during an MSLB event. All locked tubes will be sleeved and then replugged. With sleeving, the design basis requirements of the locked tubes to support the 3.0 volt IPC are met. Byron, Unit 1, is currently operating with locked tubes without sleeves at the TTS and, thus, is susceptible to similar TTS degradation as seen at Braidwood, Unit 1. Comed discussed its justification for believing that the locked tubes at Byron, Unit 1, will meet design basis requirements through the end of the current cycle. Comed used several approaches to predict the voltage distribution of TTS indications in the Byron, Unit 1, locked tubes. The size of the largest predicted E0C-8 locked tube TTS indication at Byron, Unit 1, is smaller than the calculated limit to maintain structural integrity during an MSLB event.

The methodology Comed used to predict the locked tube TTS indications was benchmarked using the Braidwood, Unit 1, results. The staff indicated the approach appeared reasonable, but asked that the operability assessment be docketed for a review of the details.

I l l 1 Comed, in a parallel action, submitted its root-cause evaluation of the circumferential crack indications of the locked SG tubes at the TTS in a letter dated April 30, 1997. Finally, in its letter dated May 23, 1997, Comed  !

submitted its proposed approach and its schedule for evaluating the recent i Braidwood, Unit 1, ECI results, uv I -

wm O r;- -

M. David Lynch, Project Manager l 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. Licensee's Handout cc w/encls: see next page i

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Comed, in a parallel action, submitted its root-cause evaluation of the circumferential crack indications of the locked SG tubos at the TTS in a .I letter dated April 30, 1997. Finally, in its letter dated May 23, 1997, Comed submitted its proposed approach and its schedule for evaluating the recent Braidwood, Unit 1, ECI results.

ORIGINAL SIGNED BY:

M. David Lynch, Project Manager ,

Project Directorate III-2 i 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. Licensee's Handout cc w/encls: see next page I

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0200i.)3 i

DISTRIBUT!oN W/enct 1 & 2: E-MAIL w/enct 1: E. Adensam tDocketc ,. PUBLIC S. Collins /F Miraglia R. Zimmerman PD3-2 r/f OGC 015 B18 J. Roe (JWR) R. Capra (RAC1) B. McCabe (BCM)

, ACRS T2E26 D. Lynch (MDL) C. Moore (ACM) D. Ross (SLM3) G. Dick (GFD)

R. Lanksbury (RDL) S. Bailey (SNB) J. Gavuta (JAG 1) S. Coffin (SMC1)

B. Sheron (BVS) C. Beardstee (CDB) E. Sullivan (EJS)

, DOCUMENT NAM : G:\CMNTJR\ BRAID BY\BECT.3097.S ,

l OFFICE KU M Tl thM l R. / 4:PD3-2 () f(i lb i NAME 6 1) { CM()6RE \ ,)CAPRA / $A l DATE 06A (197 @ '

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O I Comed, in a parallel action, submitted its root-cause evaluation of the l circumferential crack indications of the locked SG tubes at the TTS in a j

letter dated April 30, 1997. Finally,- in its letter dated May 23, 1997, Comed submitted its proposed approach and its schedule for evaluating the recent Braidwood, Unit 1, ECI results.

ORIGINAI, SIGNED BY:

! M. David Lynch, Project Manager Project Directorate III-2 l l Division of Reactor Projects-III/IV  !

Office of Nuclear Reactor Regulation -

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

Enclosures:

1. List of Attendees

2. Licensee's Handout

! cc w/encls: see next page DISTRIBUTION w/ encl 1 & 2: E MAIL w/ encl 1: E. Adensam c Docket PUBLIC 5. Collins /F. Miraglia R. Zissnerman

! PD3 2 r/f OGC 015 B18 J. Roe (JWR) R. Capra (RAC1) 8. McCabe (BCM) l ACRS T2E26 D. Lynch (EL) C. Moore (ACM) D. Ross (SLM3) G. Dick (GFD)

[ R. Lanksbury (RDL) S. Bailey ($NB) J. Gavuta (JAG 1) S. Coffin (SMC1)

B. Sheron (BWS) C. Beardstee (CDB) E. Sullivan (EJS) l DOCUMEN7 NAME: Gr\CMNTJR\ BRAID-BY\Blotl097.

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0FFICIAL RECORD COPY

Byron /Braidwood Power Stations cc:

Ms. I. Johnson Mrs. Phillip B. Johnson

Acting Manager, Nuclear Regulatory Services 1907 Stratford Lane Rockford, Illinois 61107

! Commonwealth Edison Company 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 Was'ington, n 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 1250 Eye St., N.W. 500 South Second Street Suite 302 Springfield, Illinois 62701 Washington, DC 20005 EIS Review Coordinator Michael I. Miller, Esquire U.S. Environmental Protection Agency 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 203 North LaSalle Street Springfield, Illinois 62704 Suite 1390 Chicago, Illinois 60601 Commonwealth Edison Company Byron Station Manager U.S. Nuclear Regulatory Commission 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 Commonwealth Edison Station U.S. Nuclear Regulatory Commission 4450 N. German Church Road 801 Warrenville Road Byron, Illinois 61010 Lisle, Illinois 60532-4351 U.S. Nuclear Regulatory Commission Ms. Lorraine Creek Braidwood Resident Inspectors Office Rt. 1, Box 182 Rural Route #1, Box 79 Manter.o, 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 l 110 East Adams Street Springfield, Illinois 62706

l l

Chairman . I Will County Board of Supervisors l Will County Board Courthouse l Joliet, Illinois 60434 Commonwealth Edison Company Braidwood Station Manager i

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 l Commonwealth Edison Company RR 1, Box 84 Bracemille, IL 60407 4

9

l LIST OF MEETING ATTENDEES STEAM GENERATOR INSPECTION RESULTS APRIL 30. 1997 i HEL i M. David Lynch George Dick

, Stewart Bailey Jim Gavula Stephanie Coffin Cheryl Beardslee Robert A. Capra Edmund J. Sullivan Brian Sheron Commonwealth Edison Company Jay Smith Denise Saccomando Bob Borsun i

Kenneth L. Graesser i David Wozniak i Jim Meister John Hosmen Harry Smith Roman Geisor Mike Sears John Blomgren Dominion Enaineerina Jeff Gorman Sartrex Ron Gamble Westinahouse Bob Keating i

Enclosure 1 i

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Agenda

- Introduction / Objectives .

John Blomgren Braidwood 1 Mike Sears ,

- Inspection Results

- Locked Tube Inspection -

- Tube Pull Selection ,

Conclusions Byron 1 Roman Gesior

- Braidwood Locked Tube Root Cause

- Full Cycle Operation Assessment

- Conclusions Conclusions John Blomgren

Meeting Objectives

- Present Comed Conclusions on Braidwood 1 and Byron 1 Full Cycle Operation .

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Conclusions

- Basis for Steam Generator Integrity

- Leakage < Site Allowable at MSLB (26.8 gpm Braidwood)

- Probability of Burst < 1 x 10-2 l

- Braidwood 1 Will Operate Full Cycle Until Steam Generator Replacement with Reduced RCS DEI Limit

- Byron 1 Will Operate-Full Cycle Until Steam Generator Replacement

- Provided Requested Information for Issuance of 3.0 Volt IPC Renewal  :

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- Braidwood 1 Mode Change May 15th, Comed Requests Amendment by May 9th l

l

Braidwood Preliminary Inspection Results 100% Row 1&2 U-Bend (+PT) 2 Axial /1 CircInd 1

100% Dents > 5.0 Volts (+PT) 1 Circ Ind  ;

20% Dents 2.5 - 5 Volts (+PT) -No Indications  !

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. 100% Hot Leg TTS (+PT) 287 Inds j 100% Cold Leg TTS (+PT) 35 Inds LWS (+PT) No Indications (50% Complete) 100% Full Length Bobbin 109 Inds > 3.0 Volts 1984 Inds 1.0 to 3.0 Volts 4936 Inds 0 to 1.0 Volts Locked Tube Inspection (+PT) 49 Cires at TTS

• 16 In Situ Pressure Tests No Leakage

Inspection Results Analysis .

Row 1 U-Bend Indications (PWSCC)

- 2 AxialInds (0.41",0.29")

0.41" In Situ Pressure Tested to 5000 psi, No Leakage  ;

- 1 Circ Ind (52 deg)

In Situ Pressure Tested to 5000 psi, No Leakage

Conclusion:

- All Tube Integrity Requirements Met

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Inspection Results Analysis i

Cire at 23.8 Volt Dent

- Dent Present in Baseline, No Significant Change

- 5 H - Contained Within TSP

- 71 Arc Length

- Much Smaller Than TTS Indications

- Stabilize / Plug Conclusion  !

- No Significant Degradation ofDents  ;

- All Tube Integrity Requirements Met i

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Inspection Results Analysis 3.0 Volt IPC (Preliminary)

- MSLB Leakage. Calculation "As-Found"  ;

Projected 6.99 gpm Actual 11.5 gpm l Site Allowable Leakage Limit 26.8 gpm

- Probability of Burst Projected 6.81 x 104 Actual 1.9 x 10-5 Generic Letter 95-05 Requirement < 1 x 10-2

- EOC.7 IPC (Preliminary Results)

Projected MSLB Leakage 27.2 gpm Projected Burst Probability < 1x10-5  ;

Conclusion-

- Braidwood Unit 1 Met Tube Integrity Requirements at the EOC 6

- Braidwood Can Start-up from Refuel

- Submit Tech Spec Change to Reduce RCS Dose Equivalent Iodine Limits

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L Inspection Results Analysis

Conclusions:

L

- All As-Found Requirements Met ,

Leakage < Site Allowable at MSLB (26.8 gpm Braidwood)

Probability of Burst < 1 x 10-2 t

- Supported by In Situ Pressure Testing of Bounding Indications

- 3.0 VoltIPC Below Leak and Burst Limits

- Full Cycle Expected

- IP'C EOC Leak and Burst Calculations Will be Included in 90 Day Report

- Technical Specification Change to Reduce DEI Will Be Submitted e

l-Locked Tube Design Basis

- Maintain TSP Displacement to No More Than 0.10" During a MSLB i - Accomplished by:

l Hydraulically Expanding a Sleeve into Selected TSP Intersections .  ;

Remove 'fube From Service After Expansion by Plugging Tube Functions as an Additional Tie Rod Load Design Basis 500 lbs l

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Locked Tub.e Inspection .

49 of 85 Locked Tubes With TTS Cire Indications

- Significantly Smaller Than Pervious Tube Pulls

- In Situ Pressure Tested 7 of the. Largest Indications to 3200 psi, No Leakage

- In Situ Pressure Tested Largest Indication to > 4900 psi, No Leakage ~ .

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l Locked Tube Inspection Corrective Actions:

- All Locked Tubes Will Receive a LWS at TTS Followed by Plugging

Conclusions:

- 3.0 Volt IPC Design Basis Requirements met for "As-Found" Condition  :

- Corrective Actions Will Assure Design Basis Requirements met Until End ofNext Cycle (SG Replacement) t

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Locked Tubes Repaired with Laser Welded Sleeves i

4 Design Criteria of Locked Plugged Tubes Must Carry 500 lbs Axial Force during MSLB

- Design ofInservice LWS- Must Carry RG 1.121 Loads during Normal / Faulted Conditions (approx.1500 lbs)

- Conclusion, Locked Plugged Tubes Can Carry >500lbs

- Original Qual.ification of Lower Rolled Joint

. - Pull Test Data Corrected for Locked Tube Condition at MSLB

Conclusion:

Original Test Data Demonstrates that Locked Tube Can Carry >500 lb Load with Significant Margin Evaluation of Additional Test Data of Lower Rolled Joint

- Test Data Adjusted to Braidwood Locked Tsbe Conditions

Conclusion:

Additional Testing Demonstrates that LWS in Locked Tube

, Can Carry >500lb Load with Significant Margin

i Locked Tubes Repaired with Laser Welded

Sleeves Original Testing of Laser Welded Upper Joint

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- Tensile Load Test Performed, Weld Can Carry Approx. 9000lbs

Conclusion:

Original Qualification Testing of the Upper Welded Joint Can Carry >500 lb Load With Significant Margm

- Additional Testing of Laser Welded Upper Joint

- Doel Pulled Sleeved Tensile Test Demonstrated LWS Can Carry Up to 13,000 lbs With No Failure

Conclusion:

Additional Testing Demonstrates that the Upper ,

Welded Joint Can Carry 500lbs Load With Significant Margm

Conclusion:

LWS Meets All Design Requirements for a Locked Tube and Is An Acceptable Repair With Significant Margin

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t IPC TUBE PULL REQUIREMENTS j t

l l - Generic Letter 95-05 Requirements

- Minimum of Two Intersections

• Selection Criteria .

- Emphasis on Large Voltage Indications

- Cover a Range ofIndications including NDD in Mctions

- Representative Sample of SAI's as Compared to Mars Indications

- Braidwood Strategy

- Pull Largest Accessible SAI (2 Intersections Per Tube) 8.93 Volts,1-NDD, SG A 6.08 Volts,1-NDD, SG A l- _ _ _ _ _ _ _ - _ - - _ _ _ _ - _ _ _ _ - - _ _ _ - _ _ _ _ _ _ _ _ _ - - - _ _ _ . _ - _ _ _ .-

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Braidwood 1 Conclusions -

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As-Found Condition of Steam Generators Met all .

Requirements (Both Locked and Inservice Tubes)

- Leakage < 26.8 gpm at MSLB

- Probability of Burst < 1 x 10-2

- In Situ Pressure Testing of Bounding Indications, No Leakage

- All Locked Tubes Capable of Carrying 500 !bs Load

- Full Cycle Operation Until Steam Generator Replacement  ;

Anticipated

- Technical Specification Change to Reduce DEI Will Be Submitted  :

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Braidwood 1 Locked Tube Root Cause Objective: Identify the Reason for Discrepancy Between Frequency ofInd.'s in Locked and In-Service Tubes at Braidwood 1 Issues Investigated Relevant to ODSCC

- Materials

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- Stress

- Environment .

- Temperature

- Fabrication

- Growth Rates Basis Strain Gage Results from Tube Locking Field Qualification Tests; Axial Stress at TTS Ranges &om 2.5 ksi to 32 ksi for Different Lock Configurations Largest + Point Indication Voltages at Tubes Locked at Lowest Support (3H)

Estimated Temperature Difference Between TTS HL In-Service Tube and HL Locked (Plugged) Tube is Approximately 50oF ECT Signals Same for TTS Circ. Ind.'s in Locked Tubes and In-Service Tubes

Locked Tube Root Cause Conclusion Tube Locking Process Induces Axial Stress at TTS Sufficient to Grow Indications In-Service > Detection Threshold

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Locks at Lowest Elevation (3H) Induces Sufficient Axial Stress to Grow Cracks Deeper than Locks at Higher Elevation Reduced Temperature Affects due to Tube Plugging Not Sufficient to Overcome Increased Stress Affects on ODSCC Growth No New Mode of Degradation, Cracks are Circumferuntial ODSCC at the Roll Transition

j Byron Locked Tube TTS ODSCC

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Operability Assessment Objective: Verify Structural Integrity of Locked Tubes to Ensure Design Basis is Me~t at EOC-8  :

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Assess StructuralIntegrity

- Predict EOC-8 Size of Locked Tube TTS Cire. Ind.'s Using Byron  !

Growth Data

- Non-Burst Structural Limit (From In Situ Pressure Test Data)

- Braidwood In Situ Test Results

- Benchmark Method Against Braidwood As-Found i

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Byron Operability Assessment Methodology Byron End of Cycle 8 Locked Tube TFS Cire. Indication Prediction Methodology.

BOC Distribution Growth Distribution NDE Uncertainty EOC Distribution t = 630 Ind -l- Ind -l- Ind -

NDE Parameter NDE Parameter NDE Parameter NDE Parameter 85 Ind's atDetectionThreshold Byron Growth Rates (From NDE Uncertainty 0.3 V Assess AgainstStructural of 0.3 V Max,0.1 V Avg. NDD)+ Brwd.LockedTube Max,0.32 V Avg. Limit Growth Rates Methodology Benchmark Against Braidwood 1 Locked Tube As-Found BOC Distribution Growth Distribution NDE Uncertainty EOC Distribution t = 412 Ind -l- Ind -l- Ind  : I i

NDE Parameter NDE Parameter NDE Parameter NDE Parameter P

85Ind'satDetectionThreshold Braidwood Growth Rates NDE Uncertainty 0.3 V ComparetoAs-Found of 0.3 V Max,0.1 V Avg. (From NDD)+ Brwd. Max,0.32 V Avg. Distribution LockedTube GrowthRates

By. ' and Braidwood ODSCC Cire. Crack Growth Rates (Ind's from NDD) '

Max Vcitage ,

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E Brd. Growth Freq. I E Byron Growth Freq.

O Locked Tube Distribution Frequency 0.3 -

Number of Points:

Byron: 565  !

0.25 {- Braidwood: 258 Ludeu Th. 49 i

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l 1997 Braidwood Unit 1 Benchmark Locked Tube Predicted Vs. Actual RPC Max Voltage Distributions (TTS Cire. ODSCC) 18 ,

E Brd. As Found O Predicted # of Tubes 16 Predicted Distribution BOC = 85 Ind's,0.3 Max. Volts (Detection Threshold) 14 ' GrowilrRattrrBrd 10/96 ind s, NDD in i0/95 + Locked ' .

Tubes, NDD 10/95 (dV/1 year)

Time = 412 Days 12 inciuderNDE Uncerininty 10 -

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RPC Max Voltage, volts Predicted Distribution is Conservative and Bounds As-Found Locked Tube Indications, Benchrnarks Methodology for Use on Byron 4r28/971:48 PM BWD4971N.XLS ch brd pred vs act max

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Byron Unit 1 EOC-8 Predicted Locked Tube Indication Distribution RPC Max Voltage, Braidwood Benchmark Method 20 O Byron Predicted # of Ind's Benchmark I "

OC - 85 nd s 0.3 a Volts (Detection Threshold)

Growth Rate = By. 10/95 & 4/96 Ind's, NDD in 10/94 +

E Brd. # of Locked Tubes 97 RPC Max Brd. Locked Tubes, NDD 10/95 (dV/1 year) 16 - We_=_630_ Days includes NDE Uncertainty 14

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Byron Operability Assessment 1 L

- Byron Predicted EOC-8 Locked Tube Distribution Less than Structural Limit (4035 psi) Margin of 2.8 to Required MSLB Load of 500 lbs -

- Largest Braidwood Locked Tube TTS Cire. Ind. Insitu Tested to 4900 psi (Margin of 3 to MSLB Load)

Conclusion:

Byron Locked Tubes will Meet Reg 1.121 Load Carrying Requirements at EOC-8 i

i i

In Situ Test Load Conditions Tube Locked at TSP due to Corrosion g TSP Si =62 F2= TSP Y Reaction Force -

=61 Fi =F2 -

L, >>>L, 36' 3,g g ,F= Erd Cap Force PressurexTube In Situ ProbeUpper 4900 ps.i x 0.35 in2

.UE ----.

uWWL n  !

S,L 2 2 6.4" p

V . , .

V '

Tube Sheet In Situ Probe Lower

\ M Flaw i

l Gripper Based on Simplified Stmetural Analysis ofthis Model 85 - 90% ofLoad is seen at TFS 1

Finite Element Model ofthe In Situ Loading Condition at 4900 psi on a Tube Locked at i the TSP and TFS is 1583 lb for a Shallow Flaw and 1242 lbs for a Deep Flaw l Therefore the Tube is Tested for Axial Strength > 500 lbs Testing Performed Consistent with EPRI In Situ Pressure Test Guidelines

-Braidwood 1 Conclusions Addressed Full Cycle Locked Tube Integrity Repaired AllIndi. cations Requiring Repair

- Met AH "As-Found" Leak and Burst Requirements as Demonstrated by IPC Analysis and In Situ Results

- Preliminary EOC 7 IPC Calculations Show Full Cycle Requirements Met

- Technical Specification Change to Reduce DEI Will Be Submitted Therefore, Meet All Regulations

- Reg Guide 1.121

- 3.0 VoltIPC '

i i

Byron 1 Conclusions

- Analysis Shows Locked Tube Integrity Maintained With Margin .

r 1

~

Conclusions

- Basis for Steam Generator Integrity

- Leakage < Site Allowable at MSLB (26.8 gpm Braidwood)

- Probability of Burst < 1 x 10-2

-i t

- Braidwood 1 Will Operate Full Cycle Until Steam -

Generator Replacement with Reduced RCS DEI Limit

- Byron 1 Will Operate Full Cycle Until Steam Generator Replacement

- Provided Requested Information for Issuance of 3.0 Volt i IPC Renew.al

- Braidwood 1 Mode Change May 15th, Comed Requests Amendment by May 9th ,

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