ML20210Q128

Summary of 970723 Meeting W/Util in Rockville,Md Re Util Assessment of Spring 1997 Eddy Current Insp of Plant SG Tubes.List of Attendees & Handouts Presented Encl

ML20210Q128
Person / Time
Site:	Byron, Braidwood
Issue date:	08/25/1997
From:	Lynch M NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9708280142
Download: ML20210Q128 (32)

Text

_ . _ _ _ _ _ _ _ . _ _ _ _ _ . . _ _ __ ___ _ . . _ _ . _ . _ . _ _ . _ . _ . _ _ _ _ _ . _ .

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UNITED STATES -

4 1 NUCLEAR REGULATORY COMMISSION k i .W ASHINGToN, D.C. SneeH001 ig, - .

August 25, 1997

i

- LICENSEE

Connonwealth Edison Company (Comed)

FACILITIES: Byron Station, Unit 1, and Braidwood Station, Unit 1 j I SUMARY: SUmARY OF JULY 23, 1997, MEETING ON COMED'S ASSESSMENT OF THE SPRING 1997 ED0Y CURRENT INSPECTION OF BRAIDiOOD, UNIT 1 On July 23, 1997, the NRC' staff met with representatives of Comed in Rockville, Maryland, to discuss Comed's assessment of the spring 1997 eddy ,

current ins >ection (ECI) of the Braidwood, Unit 1, steam generator (SG) tubes.

i A list of t1e attendees is provided in Enclosure 1. A copy of the licensee's '

. presentation is provided in Enclosure 2.

. The staff's concern in this matter was that the as-found ECI indications in i the higher voltage range (i.e., the tail of the distribution) at the end of i cycle (EOC) 6 were higher than.those predicted in November 1995 at the start

of cycle 6. At that time, Braidwood, . Unit 1, implemented the license amendment which revised the technical specifications (TS) to allow outer diameter stress corrosion t. rack (ODSCC) flaw indications between 1.0 and 3.0 volts to remain in service. Prior to the ECI data acquired at Braidwood, L Unit 1, in spring 1997, the methodology in Generic letter (GL) 95-05 used by licensees implementing the 1.0 volt alternate repair criteria for ODSCC flaws had resulted in predicted voltage distributions at EOC which were more conservative than the as-found. eddy current voltages.

Comed proposed in.this meeting that the unconservative voltage prediction in

_ the upper range of voltages at the end of cycle 6 for Braidwood, Unit 1, was due to voltage growth rates which are dependent on the voltage of the ODSCC

, indications left in service. Specifically, Comed found that 00 SCC indications left in service between 1.1 volts and 3.0 volts grew faster than those less than 0.7 volts. Using voltage dependent flaw growth rates, Comed stated that

it could thereby conservatively predict the EOC voltage indications-in the 4

higher voltage range (i.e., above 5 volts). The net effect of this proposed approach is to increase the projected EOC SG tube leakage from ODSCC flaws under postulated accident conditions over that which would be predicted using the prescribed methodology in GL 95-05 and in the 3.0 volt license amendments for Braidwood, Unit 1, and Byron, Unit 1. Both Comed and the staff agreed that the method proposed by Comed is consistent with the Braidwood, Unit 1, TS which reference GL 95-05 since this generic letter encourages licensees to look for a voltage-dependent growth rate. ,

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Additionally, Comed discussed an error it had found which affected the evaluation of the margin for radiation exposures in the event of a main steamline break. Basically, Comed and Westinghouse had compared the predicted EOC SG tube leakages from ODSCC flaws evaluated at room temperature with the site allowable leakages evaluated for Byron, Unit 1, and Braidwood, Unit 1, in the hot condition. Correcting the latter values to room temperature reduces the site allowable leakage rates by 30 to 40 percent from the hot condition due to the differences in water density, thereby reducing the margin. In the ensuing discussion, it was stated that this error may be generic.

Accordingly, Westinghouse and NEI are pursuing this issue to determine if it affects other facilities.

Accounting for the error discussed above and the larger predicted EOC SG tube leakages from ODSCC flaws using voltage dependent growth rates, Comed further stated that the dose equivalent (DE) 1-131 concentration for Braidwood, Unit 1, would need to be reduced from its present TS value of 0.35 microcuries per gram to 0.10. Comed stated that the previous license amendment request for Byron, Unit 1, to reduce the DE I-131 concentration from 0.35 to 0.20 microcuries per gram is unaffected by the two factors discussed above.

Pending receipt of Comed's docketed submittals on these matters, the staff concluded on a preliminary basis that no mid-cycle SG tube inspections are necessary for the present fuel cycle at either Byron, Unit 1, or Braidwood, Unit 1; both of which will replace their Westinghouse Model 04 SGs at the end of their present fuel cycles.

At the conclusion of the meeting, the staff indicated that the proposed methodology using a voltage-dependent growth rate, introduced additional complexity into the prediction of E0C voltage distributions which was based on a data set from only one cycle of operation at one unit. The staff stated that further benchmarking will be necessary to validate the use of voltage dependent growth rates, before it concludes that this aaproach would consistently result in conservative E0C predictions suc1 as that demonstrated for the revised EOC voltage distributions for Braidwood, Unit 1. However, the staff believes that the proposed methodology appears to be a reasonable approach.

The staff also stated that its final decision on the length of the permissible operating cycle for Byron, Unit 1, would be made after reviewing a revised operability assessment by Comed for Byron, Unit 1. A similar staff decision

Byron /Braidwood Power Stations

- cc:

Ms. I. Johnson Mrs. Phillip B. Johnson Acting Manager, Nuclear Regulatory Services 1907 Stratford Lane Commonwealth Edison Company Rockford, Illinois 61107-Executive Towers West 111 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 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 Agtney 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 4

U.S. Nuclear Regulatory Commission 4450 North German Church Road 4

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 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 1

d Chairman. .

Will County Board of Supervisors W111' 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 4

_a

t 1

would be made for Braidwood, Unit 1, after reviewing the pending Braidwood, Unit 1, 90-day report and a pending Braidwood, Unit 1, license amendment request to lower the DE I-131 concentration.

Original signed by M. David Lynch, Senior Project Manager Project Directorate III-2 Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos. STN S0-454, STN 50-456

Enclosures:

1. List of Attendees

2. Licensee's Handout cc w/encls: see next page Distribution:

Hard Coav (w/ encl 1 & 2)

Docket ile- D. Lynch MDL PUBLIC PDill-2 R/F OGC 015B18 ACRS T2E26 R. Lanksbury RDL E-Mail S. Collins SJCl B. Sheron BWS r ,3 F. Miraglia FJM R. Zimmerman RPZ P. Rush PJR1 E. Sullivan EJS

'fY

-T. Martin SLM3 E. Benner EJB1 ' I E. Adensam EGAl S. Bailey SNB R. Capra RAtl S. Coffin-SMCI-G. Tracy GMT S. Dembek SXD G. Dick GFD \ \

C. Moore ACM DOCUMENT NAME: LYNCH \0723. SUN _ _ .

Te receive a capr of this document. IndMtp in the boat "C" = copy without enclosures "E" " Copy with enclosures "W" = No copy 0FFICE BM.19111-h (AMill-2 l @ - D:PDIll-2 l NAME- N )T dl0dFE RCAPRA >

DATE 08/sg797 U X 08/D/97 08/u/97 0FFICIAL RECORD COPY

.UC00E

1 i

LIST OF ATTENDEES FOR MEETING HELD ON JULY 23. 1997

}hmg Affiliation M. D. Lynch NRR/DRPW/PD 3-2 T. A. Pitterle Westinghouse G. Weil Nuclear Fuel Ron Gamble Sartrex Larry Alexander Comed-Braidwood Denise Saccomando Comed-NLA Mike Sears Comed-SGA/RPV Project John Hosmer Comed VP Eng Robert Capra NRC/DRPW/PD 3-2 Brian Sheron NRC/NRR/DE Phillip Rush NRC/NRR/DE/EMCB Edmund Sullivan NRC/NRR/DE/EMCB E. G. Adensam NRC/NRR/DRPW Eric Benner NRC/NRR/DRPM Stewart Bailey NRC/DRPW/PDIII-2 Stephanie Coffin NRC/NRR/DE/EMCB Steve Dembek NRC/NRR/SPO-L George Dick NRC/DRPW/PDIII-2 ENCLOSURE 1

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Agenda Li -

Introduction -

John Blomgren- ,

l

] -

ARC /IPC Leak Rate Issue John Blomgren a

1 -

Braidwood IPC Leak Rate Root Cause Mike Sears I

Braidwood Cycle 7 Projections Mike Sears Byron Cycle 8 Projections Mike Sears Conclusions John Blomgren  ;

-_____a - -_ __ -__ __ . . _ _______ __L. '__.__ __.-_m.-_----_-m___--.-_. ________m___._-.-.-_.._.-____. ...-..._...m. ____

~

Introduction / Background I

u Steam Generator Replacement Outage Progress

)'j - Byron 1; November 1997

- Braidwood I; September 1998 .

~

ll 4/30/97 Meeting Presented Results of Braidwood 1 Sixth .

] Refuel SG Inspection Significant Results:

Predicted As-Found Limit .

Leak Rate (gpm) _d 6.99 11.5 18.4 Probability of Burst 7x10d 1.9x10-5 .

lx10 2 Largest Indication 8.4 Volts 10.5 Volts -

- All Tube Integrity Requirements Met After 413 Day Cycle

.1) 20a>><. f & urt37t

Introduction / Background Last Meeting Actions a

1 -

Root Cause  !

a . .

Braidwood EOC-7 Prediction i

- Expect Full Cycle Operation

- Expect Reduced Dose Equivalent Iodine (DEI) Tech Spec Byron 1 Operate to SG Replacement j - Operability Assessment Complete ,

i s

i 6

w

, Meeting Objectives .

i Present Comed's Understanding of ARC Leakage Issue 1 - :Present Results of Braidwood 1, 3,0 Volt IPC Leak Rate  !

Root Cause Investigation Present Byron 1 and Braidwood 1, IPC Methodology Changes Which Result from Root Cause Obtain NRC Concurrence on Approach for Byron 1 and Braidwood 1 Full Cycle Operation Pending Final Approval of Tech Spec Dose Equivalent Iodine Reduction L

^

m.

Conclusions  !

n Root Cause Attributed to Voltage Dependent Growth Rates l .

l 0 Braidwood 1 Will Meet All Tube Integrity Requirements for Full Cycle Operation, with Margin, to SG Replacement  !

4 1 - RCS DEI Tech Spec Change to 0.10 Ci/gm Byron 1 Will Meet All Tube Integrity Requirements for Full '

Cycle Operation, with Margin, to SG Replacement i

- RCS DEI Tech Spec Change to 0.2 Ci/gm Margins -

- IRB Leak Rate 6.0 gpm Vs. 0.9 gpm Actual (Factor of 6) .

- Actual DEI Significantly Below Allowable (Factor of 103)

- Actual Leak Rate from Tubes will be Significantly Less than Predictions from Free Span Leak Rate (Actual ~ 0) l

~~

e Site Allowable Leak Rate Vs ARC Leak Rate ,

Discrepancy i h

4

- Problem:  ;

ll - Comed Review of Site Allowable Leak Rate Limit Calculation Discovered That Leak Rate is Calculated for Operating Pressure

i and Temperature Conditions

] - IPC Leakage Correlation is Based Room Temperature Volumetric -

Leak Rate Therefore:

i

- Comparison of the IPC Calculated Leak Rate Value, to the Site Allowable Leak-Rate Value, Without a Density Correction is i Incorrect Density of Water at Operating Conditions = 44.3 lb/ft3 Density of Water at Room Temperature = 62.3 lb/ft3

- Correction Factor is 1.406 3

, i

ARC LEAKAGE CALCELATIONS Site 10 CFR 100 l Characteristics Degradation Room Temperatur-l Analysis Leak Correlation l

o a

l ,

!! l l 1 Site Allowable ARC Predicted /As Leakage Found Leakage I

High Room )

Temperature Temperature i .

LR go7 x 0. 71 = LRg. 7.

Site Allowable Leak Rate Vs IPC Leak Rate Discrepancy Impact: -

. Site Allowable Site Allowable RT fl Leak Rate Limit

• Leak Rate Limit with Reduced Iodine i (Hot) (RT) (gr) u

., d.2W '

Byron 12.8 gpm 9.1 gpm 45.5 gpm @.ve_r ,p a n; Braidwood 9.4 gpm 6.7 gpm 67.0 gpm e 3er ,p o.<o

• Based on 1.0 pCi/gm DEI Actions:

- Comed Review Braidwood and Byron IPC Calculations as Part of -

PIF Root Cause *

- Westinghouse Performing " Potential Issue" Investigation to Determine Effects on Other Units i

- NEI S/G Working Group to Respond to this Issue

._y mcwcmes/ym af coe AtA~' -

Braidwood IPC Leak Rate Root Cause i

ll L Questions i - Why is Tail of EOC Distribution Under Predicted?

~

j - What Changes to Methodology are Needed to Accurately Predict EOC Distribution? ,

- How do you Know that the Proposed Methodology will Accurately Predict EOC Conditions?

- Root Cause Investigation Objectives

- Determine Root Cause of Distribution and Leak Rate Under-Prediction

. - Identify Methodology Changes to Address Root Cause t

= .= : 2-5 I Number of Indications y o - p w a m a w a l E 3- I g  !

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. Braidwood IPC Leak Rate Root Cause '

i

~

Root Cause Methodology i

- Scope Considers All Applicable 3.0 Volt IPC Variables

- Studies Performed to Assess Impact on 2 Criteria i How Accurately is the As-Found Distribution Predicted

~How Accurately is EOC-6 As-Found Leak Rate Predicted Methodology Application Objectives

- Benchmark Calculation Methodology Changes Using Cycle 6 Data

- Apply Methodology Changes to Braidwood 1 EOC 7 Projections and Byron 1 EOC 8 Projections 4

1 4

i i

! . Braidwood Unit 1 IPC Leak Rate Discrepancy Root Cause Scope I i

h Variable EOC-6 Evaluation Conclusion e

M =

increases LR Slightly. EOC Under-Predicts Distrltumon and

Add Mid-cycle Repaired inds to EOC

.,' Under-Predicled Lealt Race Increases LR, EOC segnirscanely Under-Predicts Distreulion and i N Constant POO (0.4) Under-Predicted

' Leak Rate [

POPCD (Voltage Dependent POD) Decreases LR. EOC Under-Predias Distreullon and -

p' Significanny Under- Predicted Leak Rate 4 GL 95-05 Growth Rate :- ^^_: :?g-j Cycle 6 Growth Rales increases LR and EOC Under-Predids Distreugnon and Distribution Sirc. '"a Leak Rate .!

P Voltage C:;:n f:2 Growth Rates < i increases LR and EOC Over-Predicts LR, Best Preects i a Cyde 6 Growth Rates

~

Distribution O6rs'", EOC distribusson [

Using Days > M Vs. EFPD  !

Cycle Length sane N k C@

Increases LR Shghtly g including NDE UncertairWy in i ound R lon Slighly

' Eddy CurrerW Uncertainty Uncensinty  :

Distreution i

Useng Volts in POL Vs. j voltage Vs. Probability of Le kage Correlation Change EOC Distreution Affect on LR {

IRB Testing of Braidwood Tube I Voltage Vs. Leakage Correlation IRB Leak Rate Value has Margin Pull (5.6V) Results in 0.9 g rn Vs. 6.0 gpm Does not Address EOC Distribuldn No Segnificant increase in Teenperature Effects indscation Growth Rates at f Lower TSP Elevation  ;

i

Conclusion:

Voltage E:;:..f:M Growth Rates are the Root Cause l I

t- .

i .

Braidwood Unit 1 Predicted EOC-8 Voltage Distribution Using Cycle 6 GL 95-05 Growth Rates Compared to Cycle 6 As-Found > 3.0 Volts 8 ,

4 DEOC As-Found E EOC Predided 6

~

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BotMn VoMage, voMs ,

7#17197 950 PW Weoces2 uns ch br6 tw6 ddep

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l .

Braidweed Unit -1 Cycle 6 Growth for Dree BOC Distributions (SG-C + Largest Growth in SG-A) CPDF l Distributions l

l g 'g '

! h & 5 h g- g s- s- @ @ @ S*'* @ @ Ej.[.E T T-T-T-'"

l y e "* , e. e e* *~ ,.x.x-x-x-r **

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. y x- x *~ x x. .- '

0.8- *' I"

x. BOC Voltage Ranges u

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-Up to 0.7 voit (1230) 4 3 e- .-

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I - c- 0.7 to 1.1 volts (665) t i a F 3 .C .

j 0.5-

. -- r --Over 1.1 volts (208) c,, .x 5 0.4 - ,' - e-- Total 5

• E r 0 03 - f ;'-

x 0.2 - .; ,

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g

~

"g d'E'n '4 e E 4'E t d'd j 3 g  ;

• j'd'* g Vokage Growth / Days > 500F

Conclusion:

Indications with Larger BOC Voltage (i.e. Over 1.1 Volts) Exhibit Higher Growth

3.0 V IPC Leak Rate Root Cause n

un Ind Voltage Ind Vdtage Ind Voltage p BOC6

! C. BOC6 BOC6 .

• Distribution Distribution Distribution

< 0.7 Volts 0.7 - I.1 Volts > 1.1 Volt j

On Y Y Y l

'l X Ind Voltage Ind Voltage h

~

Ind Voltage Growth

r Growth Growth l Distribution Distribution Distribution l 0 i V V V n

Q a

+ Q

+ = k>

Ind Voltage Leak Rate Taken at I Ind Voltage Ind Voltage

& Ind Voltage EOC 6 Distribution EOC 6 Distribution EOC 6 Distribution S EOC6 Distribution (P M oed) (Cumulative) g (Predicted) (Predicted)

(Predicted)

Results: Projected = 13.1 gpm As-Found EOC-6 = 11.5 gpm

Conclusion:

Voltage Dependent Growth Rate Methodology is Benchmarked

,j '

Braidwood 1 Predicted EOC-6 Voltage Distrftstion Using Cycle S Voltage Dependent Growth Rates Compared to Cycle 6 As-Found, > 3.0 Votis a

OEOC h

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conckskm: vanage Dependen. Growth Rate Methodology More Closely Simulated Tall of EOC DisMtenon 7n727953 PM Esoeser* e tr7 tse despe ywsh

Braidwood IPC Leak Rate Root Cause Conclusion r'

- Indications With Larger BOC Voltages Exhibit Increased Frequency

, ofLarger Growth During the Cycle

- Voltage Dependent Growth Rates Only Variable to Satisfy EOC .

Indication Distribution and Leak Rate Benchmark Cdtena Why Voltage Dependent Growth Rates were not Seen in Previous Cycles?

- Change From 1.0 Volt IPC to 3.0 Volt IPC Allowed Larger Indications to Remain in Service at BOC 6 Leading to Larger EOC Indications

- Following GL 95-05 Required Cycle 5 Mid-Cycle Inspection (1.0 Volt IPC) Which Removed Largest and Highest Growth Indications

es

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kk M Braidwood 1.0 Volt IPC gg 4 g Refuel 4(459 Days) a 1 O t,h

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Braidwood 1.0 Volt IPC g[ Mid-Cycle (283 Days) e]

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b3 Id - Braidwood 3.0 Volt IPC 4 kk Q~

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Refuel 5 (203 Days) I mr e u C

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Refuel 6 (413 Days)

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25 Y{' g Braidwood Replacement ja. @

1~ (475 Days Planned)

N 00 9

Braidwood Cycle 7 Tube Integrity Cycle 6 Met All Tube Integrity Requirements

- Previous Cycle 6 Duration (413 Days > 500 F)

- Projected Cycle 7 Duration (475 Days > 500oF)

Application ofIPC Voltage Dependent Growth Rate i Methodology

- Results (475 Days); g5 Projected EOC 7 Leak Rate = 57.1 gpm (Bounding SG C)

Largest Voltage Indication = 14.5 Volts

- Conclusion

- Conservative Braidwood EOC 7 Leak Rate Prediction

- Full Cycle Operation Justified With 0.10 Ci/gm DEI i l

- Margins l - IRB Leak Rate 6.0 gpm Vs. 0.9 gpm Actual (Factor of 6)

- Actual DEI Significantly Below Allowable (Factor of103)

- Actual Leak Rate from Tubes will be Significantly Less than

Predictions from Free Span Leak Rate (Actual ~ 0)

L

Byron Cycle 8 IPC Leakage

- Byron EOC 8 Projected Leakage = 19 gpm (600 Days) l 2 Evaluations Performed

- Application of Byron Cycle 7B Voltage Dependent Growth Rates to Byron BOC-8 = 22.8 gpm (500 Days) M

- Application of Braidwood Cycle 6 Voltage Dependent Growth Rates to Byron BOC-8 = 27.5 gpm (500 Days) K7-

• Conclusion

- Full Cycle Operation With 0.2 Ci/gm DEI

- Margins

- IRB Leak Rate 6.0 gpm Vs. 0.9 gpm Actual (Factor of 6)

- Actual DEI Significantly Below Allowable (Factor of 103)

- Actual Leak Rate from Tubes will be Significantly Less than Predictions from Free Spaa Leak Rate (Actual ~ 0)

~ s o

O*

Compadson of Braidwood BOC-4 and BOC-7 to Byron BOC-8 t

a BR, BOC-8 m By-BOC-s O BR, BOC-7 f 400 --

NumberofImscadons:

BR BOC-8: 2381 BY BOC-8: 3318

' BR BOC-7 3503 E

! *g 300 - -

3

! s k

20s -

z too o

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• GOOO~OOOO%55OO*NOOOOONUO&OU4O sobbinv % , m .

Cw+2-5:

1) Byron BOC-8 Distribullon is Sim5ar to Braidwood BOC-6 and Therefore it is Expeded Ihat Byron EOC-8 wis be Si;N to Braidwood EOC

2) Voltage Dependent "r-a-AA-i;ifi s Benchmarked on Braldwood BOC-6 Therefore M is Also Appropriate for Byron BOC-8 7116197 2:21 PM BOC con.zis Chartt

.._-..__..,__.2_%_.. -.,__... . . ..,

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

i .

I l Compadson of Braktwood BOC-4 and BOC-7 to Byron BOC-8 I

i 10  !

i;; i , :  !

' i:

l , ' ,' , 1 i

j l t

! : W BR, BOC-6  !

j l 5 BeBOC-8 l i

i 1 .

O BR, BOC-7 i

g - ..

, j I '  ; . Number of N: j

! I BR BOC-8; 2381

! BY BOC-8: 3316  :

( g .

BR BOC-7: 3503 sa 4

l

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2 I. i j

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Q Q Q Q 84 84 84 84  % h h h b b b b b gD

Conclusions:

1) Byron BOC-8 Distribution is Similar to Braidwood BOC-6 and Therefore it is Expeded that Byron EOC-8 wNl be SimRar to Braidwood EOC-8

2) VoNage Dependent *.rA is Benchmarked on Braidwood BOC-8 Therefore M is Also A,v+;.b for Byron BOC-8 j i

t t

l 7/18/97 2:19 PM BOC Compedson.xis Chart 1 l l

8--+ . _ _ . _ _ _ - - - - - _ _ _ _

Conclusions

! Root Cause Attributed to Voltage Dependent Growth Rates

- Braidwood 1 Will Meet All Tube Integrity Requirements for Full Cycle Operation, with Margin, to SG Replacement

- RCS DEI Tech Spec Change to 0.10 pCi/gm

- Byron 1 Will Meet All Tube Integrity Requirements for Full Cycle Operation, with Margin, to SG Replacement

- RCS DEI Tech Spec Change to 0.2 pCi/gm

- Margins

- IRB Leak Rate 6.0 gpm Vs. 0.9 gpm Actual

. (Factor of 6)

- Actual DEI Significantly Below Allowable (Factor of 103)

- Actual Leak Rate from Tubes will be Significantly Less than Predictions from Free Span Leak Rate (Actual ~ 0)

-4 l Actions

- Anticipate Byron Unit 1 DEI Tech Spec Change by 8/29/97

- Submit Braidwood Unit 1 DEI Tech Spec Change by 8/12/97

- Need Braidwood Unit 1 DEI Tech Spec Change by 10/10/97

- Byron Unit 1 Operability Evaluation Updated to Reflect New Leak Rate Number - 7/23/97

- Review of Braidwood and Byron Previous IPC Calculations

- Westinghouse Performing " Potential Issue" Investigation

- NEI S/G Working Commitee to Respond to IPC Leak Rate Calculation Issue I

m