ML20216H526

Summary of 970822 Meeting W/Util in Rockville,Md Re Followup to Series of Conference Calls on 970418,discussing Results of Recent Steam Generator Insps at Sequoyah Unit 1.List of Attendees,Handouts & Staff Questions Encl

ML20216H526
Person / Time
Site:	Sequoyah
Issue date:	08/26/1997
From:	Hernan R NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9709160296
Download: ML20216H526 (65)

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30046 0001

%q August 26, 1997 LICENSEE: Tennessee Valley Authority FACILITY: Sequoyah Nuclear Plant. Units 1 and 2

SUMMARY

AUGUST 22, 1997. MEETING WITH TVA TO BRIEF THE STAFF ON SEQUOYAH UNIT 1 STEAM GENERATOR TUBE INSPECTIONS FOR CYCLE 8 On August 22. 1997, representatives of the Tennessee Valley Authority (TVA) met with members of the U. 5, Nuclear Regulatory Commission (NRC) staff in Rockville, Maryland. The staff requested this meeting as a followup to a series af conference calls on April 18, 1997, to discuss the results of recent steam generator inspections at Sequoyah Unit 1. A list of attendees is given in Enclosure 1. Copies of the handout provided by TVA are given in Enclosure

2. Questions provided by the staff to TVA in advance of the meeting are listed on Enclosure 3. These questions are specifically related to the TVA report on the subject submitted to the NRC on August 8, 1997.

TVA representatives discussed the inspection results and gave an overview of the testing. Details were also given on TVA's condition monitoring progr>.m and operability assessments. The Electric Power Research Institute (EPRI)

Appendix H program for qualification of the Plus Point technique for detecting and sizing steam generator axial cracks was also discussed. TVA also discussed their joint effort with Pacific Gas & Electric (PG&E) and EPRI to qualify the Plus Point technique in support of developing alternate repair criteria (ARC) for axial cracks, The staff comented that TVA has made a good case for operational assessmeni.

of the Unit I steam generator tubes and that the magnetic bias Plus Point technique for testing U bends is a good idea. The staff questioned whether TVA.was going to remove a tube from one of the Sequoyah steam generators for f

the purpose of validating the Plus Point technique. TVA stated that they have determined that using a Sequoyah tube for this purpose is not necessary because the Diablo Canyon Plant steam generator tubes that have been pulled are very similar to a Sequoyah tube and would be adequate for the purpose of validation.

The staff questioned the ability to distinguish outer-diameter cracks from inner-diameter cracks. TVA explained using test results (lissajous patterns).

The staff also discussed uncertainties with destructive examinations with TVA.

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WA noted that a Westinghouse topical report (WCAP 14707) was submitted to the NRC for review and possible endorsement in August 1996. The topical report is intended to demonstrate that the steam geierator tube support plates will not displace during a main steamline break event. TVA sta ed that NRC approval of this topical report is crucial to the TVA/P3&E/EPRI ARC program i1r axial cracks and stated that additional meetings with the staff on this issue will be held in fi ll 1997, original signed by R.Hernan Ronald W. He nan, Senior Project Manager Project Directorate 113 Division of Reactor Projects - 1/II Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328

Enclosures:

1. Attendance List 2 TVA Handout 3 Staff Questions cc w/encts: See next page DOCUMENT NAME: G:\ SON \MTGSUM-8.22 To receive a copy of this document, indicate in the box: "C" = Copy without attachment / enclosure "E" a Copy with attachment / enclosure "N" = No copy OFFICE PDil-3/PM A gL PDil-3/LA C PDil-3:D ,i lc NAME RHeman:en VJS( BClayton FHEBDONYG DATE Q/ f /97 i/ # 97 ghW97 OFFICIAL RECORD COPY J

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- TVA noted that a Westinghouse topical report (WCAP 14707) was submitted _to'the NRC for review and possible endorsement in August 1996.- The topical- report is ,

intended to demonstrate that the steam generator tube support plates will not l

. displace during a main steamline break ' event. TVA stated that NRC approval of this topical report is crucial to the TVA/PG&E/EPRI ARC program for axial cracks and stated that additional meetings with the staff on this-issue will be held in Fall 1997. 1 h.

Ronald W. Hernan. Senior Project Manager Project Directorate 11-3 Division of Reactor Projects - 1/11 i Office of Nuclear Reactor Regulation i ' Docket Nos. 50-327 and 50-328

Enclosures:

1. Attendance List

2. TVA Handout

3. Staff questions cc w/ enclosures: See next page J

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SEQUOYAH NUCLEAR PLANT cc:

, Mr. Oliver D. Kingsley, Jr. Mr. Pedro Salas, Manager President, TVA Nuclear and Licensing and Industry Affairs Sequoyah Chief Nuclear Omcer Nuclear Plant Tennessee Valley Authority Tennessee Valley Authority 6A Lookout Place P.O. Box 2000 1101 Market Street Soddy Daisy, TN 3'/ 379 Chattanooga. TN 37402-2801 Mr. J. T. Herron, Plant Manager Mr. O. J. Zeringue, Sr. Vice President Sequoyah Nuclear Plant Nuclear O.oerations Tennessee Valley Authority Tennessee Valley Authority P.O. Box 2000 6A Lookout Place Soddy Daisy, TN 37379 1101 Merket i Street Chattanooga, TN 37402-2801 Regional Administrator U.S. Nuclear Regulatory Commission M.e. Jack A. Bailey Region ll Vice President 61 Forsyth Street, SW.

Engineering & Technical Services Suite 23T85 Tennessee Valley Authority Atlanta, GA 30303-3415 6A Lookout Place 1101 Market Street Mr. Melvin C. Shannon CFe*=nooga,TN 37402 2801 Senior Resident inspector Sequoyah Nuclear Plant Mr. Masoud Bajestani U.S. Nuclear Regulatory Commission Site Vice President 2600 Igou Feny Road Sequoyah Nuclear Plant Soddy Daisy, TN 37379 Tennessee Valley Authority P.O. Box 2000 Mr. Michael H. Mobley Director Soddy Daisy, TN 37379 Division of Radiological Health 3rd Floor, L and C Annex General Counsel 401 Church Street Tennessee Valley Authority Nashville, TN 37243 1532 ET 10H 400 West Summit Hill Drive County Executive Knoxville, TN 37902 Hamilton County Courthouse Chattanooga, TN 37402-2801 Mr. Raul R. Baron, General Manager Nuclear Assurance Tennessee Valley Authority 4J Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. Mark J, Burzynski, Manager Nuclear Licensing Tennessee Valley Authority 4,1 Blue Ridge 1101 Market Street -

. Chattanooga, TN 37402-2801

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ATTEMEES MtC/TVA Meetino on Auanet 22. 1997 Reaardina Steam Generator Testina h Affiliation Ron Hernan NRC-John Tsao NRC Ted Sullivan NRC Phillip Rush NRC Cheryl -Beardslee NRC R.-D. Starkey NRC Stephanie Coffin NRC Andrea Keim NRC Steve Dembek NRC Pedro Salas TVA Joe Valente TVA Helen Cothron TVA David Goetcheus TVA Clayton Webber TVA Garg Henry EPRI

-Tom Pitterle Westinghouse Enclosure 1

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1 SEQUOYAH:SUCLEAR PLA'ST CSIT 1 CYCLE 8 r

n STEAM GENERATOR

INSPECTION RESULTS j XRC PRESESTATION l'

AUGUST 22,1997

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l Agenda s Introduction Pedro Salas a UIC8 Steam GeneratorInspection Helen Cothron a Overview ofInspection Results Helen Cothron s Condition Monitoring / David Goetcheus Operational Assessment a EPRI Appendix H Qualification of Clayton Webber

+ Point a Status ofPG&E/TVA/EPRI Axial David Goetcheus PWSCC at Dented TSP Program a Summary and Conclusions Joe Valente i fsgWocsWcW1ctare gwes R1

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Introduction a This meeting will address the NRC staffs issues identified during telephone conferences April 18,1997 and discussed in letter dated May 5,1997:

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- The emergence and detectability of PWSCC at <2 volt dented intersections

- The qualification of the sizing technique used during UIC8 refueling outage a We will begin with general discussion ofeddy current inspection results a SQN UIC8 condition monitcring and operational assessment ofsignincant indications will be discussed in detail i

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UIC8 SGInspection a Background SQN Unit I Licensed 1981 i -

Westinghouse Model 51 with Inconel 600 MA tubing WEXTEX Explosive Expansions 608 Degree T-Hot ETA /Hydrazine/ Boric Acid /DMA/ Molar Ratio Secondary Chemistry Over 9,000 dented TSP intersections (denting began Cycle 1) (Unit 2 has approximately 1,000)

Cycle 8 Fuel Cycle 451 EFPD Cycle 9 Expected Fuel Cycle 457 EFPD- Licensed for 503 EFPD Normal operating difTerential pressure - 1417 psi Steam line break differential pressure - 2560 psi 3 times normal difTerential pressure - 4250 psi i

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CIC8 SG Inspection m Active Damage Mechanisms PWSCC at Row I U-bends PWSCC at dented TSPs

- PWSCC and ODSCC at the top of the tubesheet ODSCC at dented and non-dented TSPs AVB wear

- Cold leg wastage b

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C1C8 SG Inspection a UIC8 Steam Generator Scope 100% full length with bobbin coil probe

- 100% TFS with 0.080 mid range /0.080 high fbquency/0.115 mid range RPC probe

- 100% Row I U-Bend and 20% Row 2 wities bias U-Bend RPC probe

- Dented TSP inspection with + Point probe E enveloped the highest support plate with past identified PWSCC indications, which bound the critical area, and included a 20% bufTer zone 9

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SON-1 >=5 von cents INTERSECTIONS +11-1 TSP 1H 2H 3H 4H SH 6H 7H Total SG-1  ; 136 : 15 ._ 4 ~1

_0 - . 0 -. :10 168 SG-2 3151 - 21. -:2- g ; 0, ,, . ,;1 ,, , , _1. .-g d Ti_ 48 i

-27 8 1067 SG-3 L278 218' .-:- 372:-:-: 1 163 g $g 379- .p gm ~9p- 4 -we w 1'I 2681 l Total 1639 633 810 668 23 165 26 3964 7100%Zi] = 3420  ::::W::::::: = 75 Total = 3495 1

2-5 Voit Dents INTERSECTIONS +11-1 TSP 1H 2H 3H 4H SH 6H 7H Tetal i SG-1 159. 59 - .035 : 6 7 21 44 331

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SG-2 ~ 55' 98 : .::155:: 11 9 24 41 253 SG-3 632- $2S ~ 390'I" .5sii:5:- 90 342 63 2765 SG-4 '496 495 567 3907 ~ I*:i25 - 13 55 2143 Total 1344 1278 1007 1029 231 5 400 2b3 5492 EiO6M5'm '.,; = 3969 5:'2 N:5.': = 160 Total = 4129 Total Exams = 7624 Due to detection ofPWSCC in 2-5 volt dented TSPs, scope was expanded :o 10 wwicem ,- u include 100% H04 and 20% H05 in SG 3  ;

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UIC8 SGInspection a UIC8 In-Situ Testing Scope Utilizing the Draft EPRI SG In-situ Testing Guidelines, all crack-like indications were screened for in-situ pressure testing

- 47 tubes were sized and considered for in-situ testing t

- 15 tubes were tested in 2 SGs for PWSCC at U-Bends, at dented TSPs, and at the WEXTEX expansion a 1600 psi (representing normal difTerential pressure--temperature conected) a 2800 psi (representing steam line break differential pressure - temperature corrected) a 4750 psi (representing 3 times normal differential pressure-temperature corrected)

- All tubes met Regulatory Guide 1.121 burst and leakage requirements i

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.. Overview ofInspection Results Tubes C u m ula tive to D a m a g e M e c h a nis m P lu g g e d lA P C D a te T u b e s C ycle 8 P lu g g e d T o p-o f-tu b e s h e e t p rim a ry w a te r 55 238 stre ss co rro sio n cra ckin g D e n te d tu b e s u p p o rt pla te 181 228 p rim a ry w a te r stre s s co rro sio n cra ck in g In n e r ro w U -b e n d p rim a ry w a te r 5 69 stre ss co rro sio n cra ckin g D e n te d tu b e s u p p o rt p la te 28 52 o u tsid e dia m e te r circu m fe re n tial stre s s co rro sio n cra ckin g ,

T u b e s u p p o rt pla te o u tsid e 278 APC

• 9 dia m e te r a xia l s tre s s co rro sio n 3 P lu g g e d cra ckin g (A P C )

C old L e g W a s ta g e 0 4 T o p-o f-tu b e s h e e t o u tsid e 2 6 d ia m e te r s tre s s c o rro sio n c ra c k in g A n ti-vib ra tio n b a r w e a r 1 5 O th e r 5 34 T o tal Tu b e s plu g g e d (% ) 28o 645 4.6 %

A Ite rn a te p lu g gin g crite ria u tilize d a n d tu b e s n o f plu g g e d.

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Overview ofInspection Results i

SON U1C8 SG 1 PWSCC AT SON UICS SG 2 PWSCC AT DENTED TSPs DENTED TSPs  !

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i Condition Monitoring /

Operational Assessment l David Goetcheus i

Condition Monitoring a Condition Monitoring for U-Bend Axial PWSCC

- Two tubes were identified that exceeded the 0.47" axial crack length criteria assuming the flaw was 100% through wall H07+10.26"in tube RIC36 SG 3 -

0.75" long, 65% max depth, 51% average depth H07+11.24 in tube RIC84 SG 4 0.99"long,96% max depth,74.4% average depth i

- Both tubes were in-situ pressure tested 1600 usi 2800 psi 4750 psi RIC36 No leakage No leakage No leakage RIC84 No leakage 0.079 gpm 0.43 gpm

- Both tubes exhibited burst pressure above RG 1.121

- Both tubes exhibited leakage below 3.7 gpm accident leakage limit (total Icakage -

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U-Bends were heat treated UIC3

- More extensive row 1.U-bend examinatio.1 scope UIC8 m RIC84 last examined U1C6 m RIC36 last examined UIC7 m Improved detectability with mag bias row 1 probes a 100% Row I U-Bend examination UIC8

- All indications satisfied tube integrity at EOC8 s Operating conditions for cycle 9 essentially the same a Improved examination and 100% scope UICS Predict all U-Bend indications found at EOC-9 will meet RG 1.121 Guidelines 17 wwiam pm ai

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Operational Assessment  :

m Operational Assessment for U-Bend Axial PWSCC (Continued)

- Conservatively assume that U-bend ECT detection limit is 40% through wall and 0.25" length

- Flaw growth rates developed during-UIC8 outage a Average depth average growth - 0.62% l m Max depth average growth - 1%

a Length average growth - 0.17"

- NDE uncertainty +/-20%

- Therefore, if an indication was missed BOC-9, it could only grow to 61% and 0.42", which does not exceed RG 1.121 length and depth criteria of 0.71" for 100%

through wall and approximately 81% average depth for a very long crack (1.2").

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e Condition Monitoring a Condition Monitoring for Axial PWSCC at Dented TSPs

.- 41 circumferential indications detected - all smaller than the 238 degree (EPRI correlation) RG 1.121 limit for burst at 3dPyo 196 axial PWSCC indications in 165 tubes were detected a 10 tubes selected for in-situ pressure testing as bounding indications based on length, maximum depth, and voltage a Longest indications outside TSP were R36C42 (0.31") and R14C73 (0.43")

CYC8 Dent httx Average RPC BC SG Row Col Voit Lencth Deh Derwh Voit ^

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Voit Location 3' il4l 73 j~7.9. ' (0.43"" E 76% 7 56.5% 7 .11 1 27~~H01+.60 7 3

3  ;;16:_67m ::2.96 ;0,45"3162%, 41.2%n 2.14ml.85._;H01-23 ;p 0.21" 48% 27.1 % 0.58 3 30 71 <2 038" 54 % 343 % 2.23 131 H02.45 4 1 21 3.53 0.53" 61 % 31.5 % 0.79 7'DD H02.27 4 3 45 2.84 0.22" 43 % 30.6% 1.07 NDD H01+.01 4 14 29 <2 034" 84 % 69.2 % 0.90 0.73 H02+.16

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Condition Monitoring a Condition Monitoring for Axial PWSCC at Dented TSPS

. (Continued) u In-Situ pressure tested a Results -No leakage and all tubes exhibited burst pressure above RG 1.121 TSPs will not displace in a steam line break event for SGs having TSP corrosion even if the corrosion has not progressed to denting, including chemically cleaned SGs (WCAP 14707 August 1996) s Since TSPs do not displace in a SLB event, in-situ testing can be applied to assess leakage and burst

- Limiting indication outside TSP, R14 C73, did not leak

- Conservatively, assuming TSPs do displace a Largest flaws become free span a Limiting indication is R37C28 - crack length of 0.89", average depth 54.8%

- Calculated burst pressure - 5238 psi using LTL properties

- 0.90" flaw with 80% average depth would satisfy 1.43dP sw

- R37C28 has significant margin 20 fg * .'..t lcreve pres R1

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Condition Monitoring u Condition Monitoring for Axial PWSCC at Dented TSPs (Continued)

- Pulled tube and lab sample burst pressures compared to R37 C28

- Flaws bounding R37 C28 meet 1.43 SLB.

Row / Col or Sample # Lenath Ava Depth Burst Pressure (ks0 37/28 (Field NDE) 0.89" 54.8 % 5.2 (calculated based on LTL) 11/2 (Sample truth) 0.84" 80.9 % 4.47 11/4 (Sample truth) 1.05" 71.0 % 4.16 21/43 (pull tube) 0.99" 50.3 % 7.84 fag'docss 7,%1cteve pres RI 4

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Operational Assessment u Operational Assessment for Axial PWSCC at Dented TSPs A growth rate study was performed during UIC8 outage a Utilized 1997 Analysis Guidelines, reviewing past data with the knowledge that a flaw could exist a Growth rates were obtained by measuring ECT parameters two w~ays:

1. Cycle 8 sizing data utilizing EPRI Appendix H technique and sizing data from Cycle 7 production technique for + Point data. Comparison not exact since past data acquisition parameters were different. 26 total indications

2. Cycle 8 production data and Cycle 7 history production data that utilized the same acquisition parameters for + Point data. Comparison more valid. 88 total indications a Rules applied in growth study:

1. Indication must be present in history to measure growth parameter

2. Negative growth = zero (conservative) fagWocs'estnetcrere swes R1 O

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Operational Assessment s Operational Assessment for Axial PWSCC at Dented TSPs (Continued)

Growth Rate Study

Conclusions:

a + Point Appendix H Sizing Technique Average Growth Values:

Length growth / cycle = 0.06" Average depth growth / cycle = 2.%% ,

Max depth growth / cycle = 2.23%

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Growth Rate Study

Conclusions:

s Production AcquisitionTechnique:

Average voltage growth / cycle = 0.37 volts Length growth / cycle = 0.042" ID AXIAL VOLT GROWTH RATES BASED ON PRODUCTION ID AX1AL LENGTH GROWTH RATES BASED ON PRODUCTION TECHMOUES TECHNIQUES l

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Operational Assessment m Operational Assessment for Axial PWSCC at Dented TSPs (Continued)

RG 1.121 calculation for dented TSP >2.0 volts-u Based on a dented tube pulled from a similar SG and field detected with + Point, the detection threshold is 0.12",38% max depth,23% average depth a Based on worse case growth rates from EOC-8 growth rate study

- Length - 0.06" - Max Depth - 2.23%

- Average Depth - 2.96%

a Therefore,if an indication was missed BOC-9,it could only grow to 40.23% max depth, 0.18",25.96% average depth n If worse case from growth study is used (20% max depth growth,0.22" length growth, 16.73% avg depth growth)

Ave Depth Leneth Max Depth Threshold 23 % 0.12" 38%

Growth at 95% 16.73 % 0.22" 20 %

39.73 % 0.34" ;3%

His is less than the 0.90" flaw with 80% average depth which satisfies 1.43dP a pagWocs%1crere pes RI 1

e 3

Operational Assessment m Operational Assessment for Axial PWSCC at <2 Volt Dented TSPs UIC7 and UIC8 <2 volt inspections were based on bobbin coil inspection.

m Bobbin data was reanalyzed with more stringent analysis criteria EOC-8 u 5E2 tubes were identified to be potential flaws and were + Point examined.

90 were confirmed as axial PWSCC and the remainder were NDD.

m A total of 702 <2 volt dented intersections were + Point examined u Only one indication was identified by + Point that was not detected by bobbin, R33 C21 SG 4.

- Length - 0.29"

- Avg Depth - 30.5%

'- . - Max Depth -76% (single data point) m Probability of Detection (POD) = 95% at 94% confidence 26 p.gwes% ct.ve pra at

Segmysh, thtt 1, Cycle 8 ', _.

• Stes. W ater 4 Rcw 33, T.ciwn 21, lei, Inner 31ameter

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Operational Assessment

, m Operational Assessment for Axial PWSCC at < 2 Volt Dented TSPs (Continued) j - R33 C21 would indicate that the bobbin detection threshold would be slightly greater than 30% average depth for an indication of about 0.25" length.

- UIC8 field data of bobbin voltage vs + Point average depth verifies that bobbin detection isjust over 30% average depth.

SG4 R14 C16 - 31.3%

SG2 R11 C12 - 30.4%

- It is unlikely that indications in this avemge depth range would grow to exceed the structural limit of 100% which satisfies the RG 1.121 SON UIC8 Bobbin Coil Detection vs

+ Point % Avg Depth <2.14 volt Dents ,

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1 Operational Assessment m Operational Assessment for Axial PWSCC at < 2 Volt Dented TSPs (Continued)

- Conservatively, assuming TsPs displace Undetected indications left in service BOC-9 would be bound by the worse case missed Cycle 8 - R33 C21 with worse case growth from growth study ECT uncertainty based on Appendix H program - 11.9% for depth Ave Depth Leneth R33 C21 30.5 % 0.29" Growth at 95% 16.73 % 0.22" ECT Uncertainty 11.9% 0.15" 59.13 % 0.66" This is less than the 0.90" flaw with 80% average depth which satisfies 1.43dPs w fsgWesWolcre gres Rt

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l EPRI Appendix H Qualificauon of-Point, Length, Depth, & PDA ,

i i

i Clayton Webber

EPRI Appendix H Qualification of Point Length, Depth, & PDA d u Objective m Requirements m Methodology m Length Correction

! e Accuracy ofTechnique

! m Summary

. 30 x 1 3%%ia m , a

i EPRI Appendix H Qualification of

! Point Length, Depth, & PDA a Objective To detect and size axial PWSCC at dented TSPs i

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1 EPRI Appendix H Qualification of Point Length, Depth, & PDA a Requirements

+ Point Probe Frequency -300kHz Rotation Speed - 300 revolutions per min Axial Speed of Probe - 0.1 inches per second Voltage noimalized - 20 volts on 100% EDM axial indication on Cal. Standard

- Calibration Curve Established Utilizing ID Notches

. . paguacs'ardelcrarc pres RI

EPRI Appendix H Qualification of Point Length, Depth, & PDA a M~ethodology I -

Calibration is established based on multiple ID EDM notches ..

Each scan line ofindication is sized using phase analysis based on calibration curve

~

Scans are taken to the end of flaw-like response Record a zero percent call at beginning and end ofindication I

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33

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! EPRI Appendix H Qualification of

! Point Length, Depth, & PDA

! a Length Correction Data points within 0.2," of the end of flaw will be adjusted as follows

! u Ignore those that change ID to OD The following do not apply if crack exhibits primarily an OD response a Amplitudes ofless than 1 volt with ID phases greater than or equal to 85% will be ignored 4 m Amplitudes ofless than 1 volt with ID depth increases greater than 10% over approximately 0.05" spans will be ignored i

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34

EPRI Appendix H Qualification of Point Length, Depth, & PDA Axial PWSCC Based on Phase Angle Measurements @ Dented Intersedions Length Max Depth Area RMSE Sample l Met Estl Met Estl Met Estl %TW Coef Diablo 10-22 0.12 0.22 38 48 19.67 28.23 15.61 0.8 Diablo 21-43 C1 0.99 0.97 98 60 50.22 44.45 21.59 0.79 Diablo 21-43 C2 028 0.29 50 40 37.62 31.28 9.61 0.99 Sample 7 C1 0.87 0.87 100 100 96.28 93.9 9.04 0.95 Sample 7 C2 0.66 0.6 100 99 84.79 88.85 30.97 0.78 Sample 7 C3 0.13 0.1 65 64 46.14 43.2 18.06 0.85 Sample 8 C1 2.64 2.32 100 99 84.97 90.55 N.02 0.77 Sample 8 C2 2.45 2.33 100 100 83.56 92.66 24.59 0.72 Sample 9 C1 1.87 1.59 100 100 82.08 90.84 26.8 0.74 Sample 9 C2 1.71 1.71 100 100 8425 88.04 21.17 0.87 Sample 10 C1 2.56 2.36 100 100 89.94 83.33 24.14 0.91 Sample 10 C2 2.21 2.04 100 87 71.5 67.04 17.9 0.79 Sample 11 C1 0.68 0.73 100 95 98 85.49 17.33 0.66 Sample 11 C2 0.58 0.46 95 99 73.96 89.74 20.34 0.92 Sample 12 C1 1.9 1.69 100 100 87.3 86.89 42.26 0.35 Sample 12 C2 0.55 0.41 82 64 50.55 38.29 37.48 0.09 Sample 12 C5 0.18 021 90 83 70.47 5929 19.37 0.81 RMSE 0.15 11.45 8.14 22.66 0.75

%Thru-Wal POD @ 90 Fraction deteded

<50% 0.09 1.0 0 (111) 50-100% 0.86 1.00 (16/16)

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a Accuracy ofTechnique Percent Degraded Area Based on Phase Analysis had a RMSE of 8.14 l - Axial Extent Based on Phase Analysis had a RMSE of 0.15 A -

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! EPRI Appendix H Qualification of l Point Length, Depth, & PDA s Summary Average depth and length are qualified for use

- Additional samples are being produced to improve the database for average depth, I length, and maximum depth sizing .

1 37

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l Status of PG&E/TVA/EPRI Axial PWSCC at Dented TSP

. Program David Goetcheus O

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Status of Axial PWSCC at Dented TSP Program a PG&E/TVA/EPRI Appendix H Qualification Program for Axial PWSCC at Dented Intersections Program Objectives a Complete + Point Appendix H qualification to include data sets 20-70% average depth a Develop Appendix H qualification for bobbin coil detection of axial PWSCC at TSP intersections with < approximtely 2.5 volt dents a Provide a database to supy ort an ARC for axial PWSCC at dented intersections (status not presented)

Status of Objectives 1 and 2 m To date 63 cracks have been produced in 750 degree F doped steam in 55 dented TSP intersections a Burst testing and metallurgical exams are complete on 12 samples

= Lmples are representative of field flaw data Sameles (Met) Field Voltage (028 volts -3.7 volts) Voltage (038 volts -3.11 volts)

Length (0.17"- 1.05") Length ( 0.11"- 0.89")

Avg Depth (15.3% - 80.9%) Avg Depth (11.6% - 71%)

39

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k Status of Axial PWSCC at Dented TSP Program a PG&E/TVA/EPRI Appendix H Qualification Program for Axial PWSCC at Dented Intersections (Continued)

Status of Objectives 1 and 2 (Continued) m Tasks included in Objectives

- Samples packed and baked with magnetite

- ECT data collected with bobbin coil (mid/high frequency), mica probe,

+ Point, mag bias + Point, Gimbled + Point,4C4 probe,3 coil RPC, 0.080 pancake (high frequency and mid range) -

- Appendix H qualification program Pressure test 12 selected samples to fill out the + Point Appendix H qualification and bobbin coit qualification

- Burst correlations

- Fractography -

- ECT vs metallurgical correlations ,

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Status of Axial PWSCC at Dented TSP Program Summary of Bobbin Detectability for PWSCC

+ Point Destructive Exam **

Bobbin Flaw Analysis Flaw Callel Local Avg.

TSP Dent Typical No. of Max. Avg. FS Burst Max. Max. Avg.

Specimen Location Volts Volts Analysts Length Depth Depth Pressure Length Depth Depth

• Depth 1 4 2.32 2.18 4/4 0.79 87% 51.4 % 9.23 0.708 68.0% 54.3 % 39.0'4 2 5 2.32 1.70 4/4 0.93 73 % 25.5 % 10.90 0.94 41.0 % 35.5% 17.7 %

6 4 2.18 0.64 4/4 0.54 65 % 51.1 % 9.38 0.42 75.0 % 65.0% 51.3 %

8 1 1.42 0.88 4/4 0.48 73 % 40.3% 10.56 0.42 58.0 % 52.2% 40.2%

8 2 1.52 0 85 4/4 0 47 56 % 45.3% 10.90 0.47 55.0 % 48.7% 33 4 %

8 3 1.61 0.70 4/4 0 51 65 % 46.2% 11.06 0.46 50.0 % 44.2 % 33.3 %

9 1 1.34 0.52 4/4 0.47 52% 42.7% 11.12 0.424 49.0% 37.0%

9 2 1.34 3.70 4/4 0.98 81 % 70 8 % 3 94 1.01 90.0 % 84.1 % 60 8%

11 2 1.49 1.90 4/4 0.87 84 % 71.7 % 4.47 0.837 99.2 % 97.0% 80.9 %

11 4 1.95 2.40 4/4 1.00 90% 72.6 % 4.16 1.048 98 0% 7f.0%

12 4 1.39 0.11 1/4 0 41 59% 45.2% 13.17 0.53 33.0 % 26.7 % 15.3%

13 3 1.29 0.28 4/4 0.37 52 % 38 8 % 0.336 46.0% 29 0 %

R21C43 1 3.2 3.49 2/2 1.00 70 % 51.1 % 7.84 0.991 98.0 % 89.0% 50.3 % =

R10C22 2 2.31 0.49 1/2 0.46 41% 29.7 % 12.09 0.122 38.0 % 23.2% 23.2 %

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l Status of Axial PWSCC at Dented TSP

Program a PG&E/TVA/EPRI Appendix H Qualification Program for Axial PWSCC at Dented Intersections (Continued)

Conclusions a Bobbin coil detection for axial PWSCC at <2 volt dents will be submitted for Appendix H approval ,

a Samples with 20-70% average depth cracks at dented TSP intersections have been produced to supplement Appendix H Qualification for + Point average depth and length sizing u A data base of more than 60 axial PWSCC samples typical of field data have been developed for APC development 42 s e e ne- n

i I

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Summary and Conclusions l

4 Joe Valente-A, g i o

L Summary and Conclusions i

a SQN Unit 1 SGs met condition monitoring for EOC-8 m SQN Unit 1 SGs met operational assessment for EOC-9 m Appendix H qualification for bobbin coil detection of PWSCC in <2 volt dents will be submitted to EPRI by November a PG&E and TVA will continue the program for an ARC for axial PWSCC at Dented TSPs and meetings will be '

requested in the fall to discuss progress

- Need NRC to review and comment on the TSP Displacement WCAP

, fsec wo.tcreu p RI

. ._ _ _ __ _ _ _ - __ -__ L

l i

in a letter dated August 8,1997, TVA submitted for staff review a report,'Sequoyah ,

i Nuclear Plant (SON)- Special Report on Steem Generator (SG) Activities Completed q During the Unit 1 Cycle 8 (U18) Refueling Outage." The report, a 90-day report, was )

l submitted as a part of implementing the voltage-based altemate repair criteria for steam l l generator tubing. TVA will meet with the staff on August 22,1997 to discuss the results l l of cycle 8 inspection of steam generator tubes.

To facilitate the discussion during the meeting on August 22, TVA requested staff review of the report before the meeting. Because of the limited time available for the review of the report (the staff received the report on August 15), the staff performed a cursory review and had the following preliminary questions:

1. page 6-7 and 6-8. There is a considerable discrepancy between the actual and predicted voltage distribution for end of cycle 8 (EOC-8) for all four steam generators (SGs). The number of indications and bobbin voltages were under-predicted in the i non-conservative direction. (1) Explain the discrepancy (i.e., calculational error or other cause); and (2) Provide your plans to rectify the discrepancy in the 90-day report (if due to a calculational error) or address how the previous under-prediction will impact future calculations and predictions.

2. page 7-3. Because of the discrepancy in the predicted and actual voltage

, distribution, there is also a considerable discrepancy in the calculated leak rate using the actual voltage distribution and predicted voltage distribution. How has the previous under-prediction affected the projected leak rate calculations for the end-of-cycle 9, (discussed on page 7-4).

3. In a letter to the NRC dated July 30,1997, David Modeen of Nuclear Energy Institute provided the industry response to an issue of a potentialinconsistency in the assessment of the radiological consequences of a main wteam line break (MSLB). The radiological consequences of a MSLB are based on a calculated primary-to-secondary mass flow rate at operating conditions (i.e., temperature and pressure). In contrast, the primary to-secondary leakage from the projected end-of-cycle steam generator tube indications during a MSLB event is based on measurements taken at room temperature. A generic letter is being written to address this issue, but at the August 22 meeting, we would appreciate any information you can provide on how this issue is j factored !nto your 90-day report calculations. .

4. page 6 of the Cover letter. In light of defective tubes detected in the U-bend regions of the tubes, provide future inspection scope for the row 1 and row 2 U. bends.

5. pages 8 and 9 of the cover letter. TVA discussed condition monitoring for axial PWSCC at tube support plate (TSP), but not for circumferential PWSCC indications.

Please discuss why circumferential PWSCC indications were not addressed.

ENCt.0SURE 3 ,

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