ML20036A001

Summary of 930427 Meeting W/Util Re Discussions on Initial Findings of Refueling Outage 7 SG Insp.List of Attendees & Handouts Encl

ML20036A001
Person / Time
Site:	Summer
Issue date:	05/04/1993
From:	George Wunder Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9305070176
Download: ML20036A001 (34)

Text

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May 4, 1993

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L Docket No. 50-395 k

LICENSEE: South Carolina Electric & Gas Company FACILITY: Virgil.C.. Summer Nuclear Station, Unit No. 1

SUMMARY

OF MEETING WITH SOUTH CAROLINA: ELECTRIC & GAS COMPANY On April 27, 1993, South Carolina Electric & Gas Company (SCE&G)' management met with the staff to discuss the initial findings of the Refueling Outage.7 steam generator inspection. The licensee's presentation included a discussion-of the-trends of operating parameters (hot leg temperature and steam generator loop power) for the last seven cycles.

During the outage, three tubes with unusually high voltage-in'dications were pulled for laboratory analysis. The preliminary findings from the tube pull were presented; specifically, that the high voltage indications were due to multiple axial cracks within:the flow distribution baffle. The licensee also -

provided a schedule for the completion of the laboratory' analysis.

SCE&G presented their basis for startup and operation until the results of the:

pulled tube analysis are received.

Included in their basis were a determination that no unreviewed safety question exists,- a: statement that the acceptance criteria of Regulatory Guide 1.121 were met, and a commitment to limit steam generator leakage to 150 gallons per day. SCE&G will meet-with.

the. staff again when the analyses results are complete. This will be in about:

-two months.

An attendance list is included as Enclosure 1.

A copy of. the handout' provided by the. licensee is' included as Enclosure 2.

Original signed by:

George F. Wunder, Project Manager

' Project Directorate'II-I Division of Reactor Projects - 1/II Office of' Nuclear Reactor. P,egulation'

Enclosures:

1.

Attendees list 2.

Handout cc w/ enclosures:

See next.page OFC:

LA:PDZTijlIP7 PM:PD d d AD:PD21:DRPE-NAME' PDAnde M k G M b :tmw JAMitchellY DATE 05/#/93 05/or/93 05/ d /93 Document Name: SUM 0427.MTS-

• 113 BC ilLE CENTER CDPJl 9305070176 930504 PDR ADOCK 0500 5

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DISTRIBUTION:

cc w/ enclosures 1 and 2:

-Docket File NRC/ Local PDRs PD 11-1 Reading File

.G. F. Wunder E. W. Merschoff, R-II cc w/ enclosure 1:

T. Murley/F. Miraglia 12-G-18 J. Partlow 12-G-18 S. A. Varga G. C. Lainas J. A. Mitchell P. D. Anderson

-T. A. Reed B. L. Mozafari T. R. Farnholtz W. T. Russell '12-G-18 l

B. D. Liaw 7-D-26 J. Strosnider 7-D-4 G. Johnson 7-D-4 E. Murphy 7-D-4 H. F. Conrad 7-D-4 K. J. Karwoski 7-D-4 E. Jordan HNBB 3701 L. G. Plisco 17-G-21 N. Economos R-II OGC ACRS (10) cc:

Licensee & Service List i

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.g Virgil C. Summer Nuclear St'ation South Carolina Electric-& Gas Company c

cc:

Mr. R. J. White:

Nuclear Coordinator S.C. Public Service Authority c/o Virgil C. Summer Nuclear Station Post Office Box 88, Mail ~ Code 802

.Jenkinsv111e, South Carolina 29065 J. B. Knotts, Jr., Esquire

~

Winston &-Strawn Law Firm

'1400 L Street, N.W.

Washington, D. C.

20005-3502 Resident Inspector / Summer NPS c/o U.S. Nuclear Regulatory Commission Route 1, Box 64 Jenkinsville, South Carolina 29065 Regional Administrator, Region.II U.S. Nuclear Regulatory Commission 101 Marietta St., N.W., Ste. 2900 Atlanta, Georgia 30323

' Chairman, Fairfield County Council Drawer 60 Winnsboro, South Carolina 29180 Mr. Heyward G. Shealy, Chief.

Bureau of_ Radiological Health South Carolina Department of Health and Environmental Control a'

Carol'ina 29201' m

Mr. R. M. Fowlkes, Manager Nuclear Licensing _& Operating Experience i

South Carolina Electric & Gas Company Virgi1~ C. Sumer Nuclear. Station Post Office Box'88

- Jenkinsville, South Carolina 29065 Mr.; John L. Skold's, Vice President Nuclear. Operations South Carolina Electric &. Gas Company Virgil C.. Summer Nuclear. Station Post Office Box 88 Jenkinsville, South Carolina - 29065'

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o ENCLOSURE 1 ATTENDANCE LIST Staff SCE&G Other W. Russell J. Skolds R. White (Santee Cooper)

G. Lainas R. Clary T. Pitterle (Westinghouse)

B. D. Liaw R. Kelso W. Cullen (Westinghouse) i J. Strosnider J. Frick R. Pollard (UCS)

G. Johnson N. Economos E. Murphy H. Conrad T. Reed G. Wunder B. Mozafari T. Farnholtz K. Karwoski

ENCLOSURE 2 l

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South Carolina Electric &. Gas Company V. C. Summer Nuclear Station i

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x NRC / SCE&G Meeting

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B Steam Generator Tube Examination Refueling Outage 7 Results N

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April 27,1993 I

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1 V C Summer Nuclear Station

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Purpose Jack Skolds VCS Steam Generators Rollin Kelso Inspection Techniques & Methodology 4

RF-6 Results RF-7 Inspection Plan RF-7 Inspection Results Review of Cycle 7 Operation John Frick Tube Pulls John Frick Reason / Tube Selection Basis Tube Pull Process Examinations / Schedule j

Preliminary Findings Cycle 8 Operation Ron Clary j

Basis for Start-up/ Initial Operation I

Future Activities Summary Jack Skolds Discussion All t

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9 Inform NRC of Refuel 7 Inspection / Repair Results 1

9 Provide Update of Status of Pulled Tube Testing

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9 Discuss Cycle 8 Operation i

9 Discuss Future Activities I

a s s e.e eses

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j D-3 S/G AV2 AV3 Number AV1 AV4 Scheme 14H 14C I

13H 13C i

12H

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11H 11C i

10C i

4 09C i

08H 08C Inlet 07C Outlet Side Side 06C 05H OSC E

04C E

03C 02H E

02C 01H 01C TSH TSC Tube Sheet l

TEH TEC t

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V C Summer Nuclear Station i

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9 Bobbin Coil Examinations i

J Performed for Entire Tube Length e

Voltage Measurement at Tube Support Plate Locations Method used for F* Implementation in Tube Sheet Region G

Rotating Pancake Coil Examination Top of Tube Sheet - Secondary Face Tube Support Plate Indications if Accessible Small Radius U-Bends a

Method Used for L* Implementation in Tube Sheet Region i

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V C Summer Nuclear Station f$!

h !hIk k'M Refuel 6 Refuel 7 Inspection Plan All Available Tubes All Available Tubes by Bobbin Coil by Bobbin Coil All Available Tubes All Available Tubes in H/L Tube Sheet Region in H/L Tube Sheet Region by MRPC by M R PC i

All Accessible TSP Flaws All Accessible TSP Flaws Reported by Bobbin Reported by Bobbin were MRPC Inspected were MRPC Inspected Data Acquisition Mir 18 A Miz 18 A Acquisition System Acquisition System 610 ULC 610 U LC Probes Used Probes Used l

Latest Rev. Zetec Latest Rev. Zetec Acquisition Sof tware Acquisition Sof tware N/A Probe Wear Standard N/A New ASME & Transfer nar....,..

Standards

V C Summer Nuclear Station f f f M w n.v iit. n n.>... w, m.>.

Refuel 6 Refuel 7 Data Analysis Analysts Qualified to Analysts Qualified to SNT-TC-1 A,1980 edition SNT-TC-1 A,1980 edition and Classroom Portion Requirements of EPRI Guidelines Appendix 'G' Site Specific Training Site Specific Training Required Required Normallud on TSP Normalind on ASME 20%

No Minimum Voltage No Minimum Voltage Threshold Imposed Threshold Imposed TSP's Analyud TSP's Analyud per EPRI Guidelines per WCAP-13522 for Appendix 'I' Interim Plugging Criteria for Non Dented TSP for TSP Flaws in VCSNS SIG Intersections Industry Events Between Refuel 6 & Refue! 7 Raised Analyst Sensitivity for Recognition of TSP Flaws ammis...,..

V C Summer Nuclear Station Steam Generator Inspections Refuel 6 - October 1991 p)h,;. ' g.

. e1549 ? 4'u9e4 tag

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g Th Bobbin Coil & MRPC Inspections...

S/G

'A' SIG

'B' S/G 'C' Total Total in S/G 4674 4674 4674 14022 Plugged Prior to RF-6 368 617 385 1370 Sleeved Prior to RF-6 (Tube Sheet) 76 49 0

125 i

Inspected Full Length

• 4306 4057 4289 12652 by Bobbin Coll Inspected Inlet Tube Sheet 4230 4008 4289 12527 Region by MRPC i

Inspected TSP's by MRPC 19 73 38 130 Installed Sleeve Examination (100%)

76 49 0

125 I

• Sleeved tubes were Inspected with Bobbin Coll from the outlet tube end to the top of the sleeve on the inlet side.

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E Steam Generator Tube Status Refuel 6 Results i

S/G 'A' S/G 'B' S/G 'C' ALL S/G Total F# Applied 151 273 ~

161 585 Total L' Applied 44 24 18 86 T.S. Cires. Steered 5

31 17 53 Tubes Plugged-Other 2

0 150 152 Bobbin TSP Flaw MRPC NDD 8

52 19 79 Bobbin TSP Flaw MRPC Confirmed 11

.21 19 51 Leave in ' Service (F'/ L * / TSP.N DD) 203 349 198.

750 I

1. Sleeved RF 6 204 27S 75 559-

1. Plugged RF-6 13 21 169 203 Total Sleeved 285 358 92 735 l

Total Plugged 381 638 554 1573-2

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I V C Summer Nuclear Station Steam Generator Inspections Refuel 7 - March 1993 I.

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S/G ' A' S/G

'B' S/G

'C' Tota!

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Total in S/G 4674 4674 4674 14022 Plugged Prior l

to RF-7 381 638 554 1573 Sleeved Prior

,l to RF-7 285 358 92 735 4'

Inspected Full Length

• 4293 4036 4120 12449 l

by Bobbin Coll r

Inspected Inlet Tube Sheet 4008 3678 4028 11714 Region by MRPC Inspected TSP's by MRPC 99 155 187 444 l

Installed Sleeve Examination (20%)

147 0

0 147

• Sleeved tubes were inspected with Bobbin Coil from the l

outlet tube end to the top of the sIceve on the inlet side.

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Steam Generator Tube Status Refuel 7 Results P

S/G 'A' S/G 'B' -

S/G 'C' ALL S/G Total F* Applied 166 229 179-574 Total L' Applied 34 32 20 86-T.S. Cires. Plugged

& Stabillmd 6

18 13 37 hbes Plugged-Other 105 140 95 340 Bobbin TSP Flaw MRPC NDD 29 58

'84 171 Bobbin TSP Flaw MRPC Confirmed 70 97 104 271:

Leave in Service (F */ L */ TS P-N D D) 229 319-283 831 Plugged 181 255 212 648 l

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'h Steam Generator Tube Status Refuel 7 Results i

i S/G 'A' S/G 'B' S/G 'C' ALL S/G Plugged - RF-7 181 255 212-648 I

i Sleeved - RF-7 0

0 0

0 Total Plugged 562 893 766 2221 i

Total Sleeved 285 358.

92 735 l

Total Effective Plugged 12.34 %

19.49 %

16.49 %

16.10 %

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i V C Summer Nuclear Station i

.i NDE Summary 1

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O All Available Tubes (i.e. Not Plugged)

Examined by Bobbin for Full Length and j

by MRPC in H/L Expansion. Transition Region.

j in Refuel 6 & Refuel 7

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All Accessible TSP Flaws MRPC Examined by MRPC (Indications Inaccessible to MRPC were-i Plugged) i 1

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Probe Wear and IPC ASME Transfer Standards a

used in' Refuel 7 9

Data Analyzed per TSP-IPC WCAP #13522 in Refuel 7 1

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No Minimum Voltage Threshold Imposed for;

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'4 TSP Flaws-li 5

9 Industry: Events Between RF and RF-7 Raised-Analyst Sensitivity. for Recognition.of TSP Flaws:

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V C Summer Nuclear Station Refuel 7 Results

[ffhp hhjh hg.3g.ms o-i 5 Indications Exceeded 3.7 Volts l

Out of 12,449 Tubes or 99,592 Hot Leg TSP /FDB Intersections a

i S/G Row Col Volts Location l

B 42 43 22.32 01H + 0.00 i

B 28 41 11.59 01H + 0.00 B

33 20 9.84 01H + 0.00 i

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31 45 7.72 01H + 0.00 B

30 45 6.02 01H + 0.00 i

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1 01H is the Flow Distribution Baf fle Plate

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RRE18 4(#98 l

V C Summer Nuclear Station fMr [

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9 Cycle Operating Characteristics & Transients G

Chemistry 9

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Hot

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S S/G Loop Power S

S/G Heat Flux I

G Feedwater Temperature i

G Cycle Comparison Summary

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Cycle Operating Characteristics 445 EFPD

>94% Capacity Factor for Cycle 4

S Transients 3 Rx Trips - 1 Trip from 100% Power i

3 Plant Shutdowns l

18 Plant Power Reductions lf Slight Increase in Steady State Leakage 1

Following Trips & Power Reductions Total Leakage Increase of <12 GPD Over Cycle l

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V C Summer Nuclear Station khhh{$hbhkhj Y AY# ?

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• e Chemistry Within EPRI Guidelines No Out of Spec. Primary / Secondary Operation J

Independent Review of Cycle Chemistry j

No Known Correlation Between Atypical i

Voltage Growth and Chemistry Found 1

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V C Summer Nuclear Station

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Cycle Loop 'A' Loop 'B' Loop 'C' Avg.

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616.90 615.60 616.60 616.37 2

615.90 616.20 616.50 616.20 3

618.40 615.90 617.50 617.27 t

4 617.50 614.90 616.10 616.17 5

617.90 617.00 616.30 617.07 4

6 618.70 617.50 617.20 617.80 7

619.20 617.10 616.00 617.43 1

Dev.

2.3

• F 1.5 ' F

-0.6*F 1.06

• F

V C Summer Nuclear Station Loop Power (MWth)*

Cycle Loop ' A' Loop 'B' Loop 'C' 2

914.7 917.7 941.7 i

3 926.8 906.2 953.1 i

4 927.8 909.6 933.8 5

918.5 916.8 937.3 6

930.3 895.2 947.5 7

923.0 918.0 945.9

• • 8 t

• Loop Power Controlled by Loop RCS Flow Rate

" Predicted Cycle 8 30F98sG 040tB 1

V C Summer Nuclear Station

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9 Heat Flux Increases as Tubes are Plugged 9

Steam Pressure and Secondary Temperature Decrease with Plugging 9

S/G 'B' Heat Flux is the Intermediate of

'A' and 'C' Steam Generators 4

9 Hide-Out Return Studies Indicate Similar Contaminant Loading Between S/G's

V C Summer Nuclear Station ff h

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435 F Design Temperature 9

433

• F Current Temperature i

Decrease Due to Feed Water Heater Fouling i

and Plugging 9

Negligable Affect on Hot Leg Temperature Due to Pre-Heater i

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V C Summer Nuclear Station N M kwXw.imhd 9

All 3 S/G Experienced Same Cycle History Transients Chemistry 9

Slight Increase in Steady State Leakage i

Experienced Following Trips &

Power Changes S

THot Increase for All S/G is Slight Increase for 'B' - Is Less Than ' A' THot Increase Appears to be Too Srnall to Account

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For Voltage Growth 9

S\\G Loop Power is Lowest in 'B' S/G S

Heat Flux is Increasing in All S/G 1

'B' S/G Heat Flux Less than 'C' Greater Than 'A' A

l 9

Feed Water Temperature...

Only Affects Pre-Heater

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Temperature Decreased by ~2 F

G No Known Correlation Found Between These 7 Parameters & The Atypical Voltage Growth of the 5 FDB Indications l

9 Search for Causative Factor (s) Continues

V C Summer Nuclear Station 4

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Atypical Voltage Indications P

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Only Method to Fully Characterize Indications i

4 9

Check Correlation of Atypical Indications to WCAP 13522 Predictions 9

Extend Industry Data Base for High Voltage Signals 9

Obtain Burst, Leak and Crack Morphology Data for High Voltage Signals 3

I J8P93 3 84893 1

V C Summer Nuclear Station Complete Receipt Inspection, Visual Examination Photography, ECT, X-Ray Radiography, UT, X-Ray Diffraction of Deposits, Silastic Molds Scheduled To Be Complete By:

05/18 Leak Testing Burst Testing 0 6/11 Preliminary SEM Fractography of 4

Burst Fracture Faces Complete Destructive Examination Conduct any ESCA-AES Chemistry Examinations on Surface Deposits 06/17 Issue Summary Letter of Key Results 09/24 Final Report Issue

V C Summer Nucleai Station hhhikbNNkIN!

O Population of Atypical Voltage Indications was 5 Indications out of 99,592 Hot Leg Intersections 9

Tubes Damaged During Tube Pull Tubes were subjected to Loads on the order of 1/2 Yield for a Virgin Tube During Deflection Tests Post Pull Bobbin & MRPC Voltages Increased by Factors of 2 to 4.

(Provide Very Conservative Results) 9 Cracks were Contained within the FDB 9

Multiple Axial Cracks Found in Pulled Tubes with Apparent Cellular Involvement S

Cracks Isolated to Quadrant in Contact with FDB S

If Atypical FDB Voltage are Excluded, Average Growth Rates for Cycle 7 are Lower than for Cycle 6.

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i Basis for Start-Up/ Initial Period of Cycle 8:

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Operation 1

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V C Summer Nuclear Station diNihFe WahOlii Safety Evaluation Performed to Determine Interim Operating Period 9

No Unreviewed Safety Question Determined per 10-CFR-50.59 9

Acceptance Criteria - RG 1.121 9

Used WCAP-13522 IPC Methodology 9

Conservative Interim Period Determined to be 3.6 Months S

Evaluation will be Updated to Incorporate Additional Analysis of RF-7 Inspection Results & the Pulled Tube Exam. Results 9

SCE&G will Limit S/G Leakage to 150 GPD

V C Summer Nuclear Station swwwMkhww ap% -NIS dkhiliIhi

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All Tubes with Detectable Cracklike Indications were Removed From Service Regardless of Through Wall Depth l

9 Enhanced Inspection Methods Utilized in RF-7, as opposed to RF-6, Reduces the Probability of Leaving Tubes with Small Defects in Service O

Continuous Leak Detection Monitors are Used

- On Line Condenser Off Gas Monitor.

Sensitivity is 3 x 10-' micro curies /cc to 6 x 10 2 micro curies /cc based on Xe = 133

- On Line S/G Blowdown Liquid Monitors Sensitivity is 10 to 2 x 10 micro curies /cc equivalent to Cs-137

- All of These Read Out and Alarm in the Control Room - Set Point is 2 x Background j

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V C Summer Nuclear Station f'pf 3Rdy.e,agimno

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Complete Review of RF-7 Inspection Data 9

Complete Review of Previous Cycle Operating Data t

S Complete Pulled Tube Testing 9

Evaluate Results of Pulled Tube Tests G

Determine Effect on Remainder of Cycle 8 Operation P

Operational Limitations Length of Operating Cycle (Mid Cycle Outage - If Required) 9 Assemble Information 9

Meet with NRC in Late June /Early July to Discuss Results (Timing well within Interim Operating Window)

V C Summer Nuclear Station 4

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4 9

Reviewed Refuel 7 Inspection Results 3

L 9

Reviewed Cycle 7 Operation 7

4 9

Discussed Tube Pull Process 9

Presented Preliminary Findings O

Presented Basis for Start-up/ Initial i

j Cycle 8 Operation l

9 Discussed Future Activities f

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