ML20117L601

Cycle 7 Refueling Outage Apr- June 1996 Results of SG Tube Isi

ML20117L601
Person / Time
Site:	Sequoyah
Issue date:	07/02/1996
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20117L596	List: ML20117L594 ML20117L601
References
NUDOCS 9609170070
Download: ML20117L601 (88)

Text

_ _ _ _ . _ _ _ - _ . . _ _ _ _ _ _ _ . _ _.

! . W :-

i

! TVANUCLEAR l Sequoyah Nuclear Plant  ;

i l 1

l Unit 2 Cycle 7 Refueling Outage 4

l April- June 1996 l 1 1 1

l l RESULTS OF STEAM GENERATOR TUBE INSERVICE INSPECTION l

(AS REQUIRED BY TECHNICAL SPECIFICATION SECTION 4.4.5.5.b) i l RESULTS OF ALTENATE PLUGGING CRITERIA IMPLEMENTATION l (AS REQUIRED BY COMMITMENT FROM TECHNICAL l SPECIFICATION CHANGE 95-23) 9609170070 960930 8 DR ADOCK 0500

}*

i TABLE OF CONTENTS l

INTRODUCTION 3 SG TUBE INSERVICE INSPECTION SCOPE AN RESULTS 4 Table 1

SUMMARY

OF SEQUOYAH UNIT 2 CYCLE 7 SG EDDY CURRENT INSPECTIONITUBE PLUGGING RESULTS 6 Table 2 RESOLUTION OF DEFECTIVE TUBES AND ALL SERVICE-INDUCED WALL LOSS INDICATIONS 7 ALTERNATE PLUGGING CRITERIA RESULTS 28 LOW ROW U-BEND INDICATION RESULTS 29 CONCLUSIONS 30 ATTACHMENTS 1 WESTINGHOUSE ELECTRIC CORPORATION SEQUOYAH NUCLEAR PLANT UNIT 2 CYCLE 8 ALTERNATE PLUGGING CRITERIA REPORT 2 STEAM GENERATOR TUBE INTEGRITY ASSESSMENT FOR U-BEND PWSCC INDICATIONS I

i 1

i l

2

! INTRODUCTION ,

i l During the scheduled Sequoyah Nuclear Plant (SON) Unit 2 Cycle 7 (U2C7)

refueling outage extensive inservice inspections were conducted in all four

steam generators (SGs). The results of the inspections were classified as C-2  :

! for all four SGs. Alternate plugging criteria was implemented during this l

} inspection due to the detection of outside diameter stress corrosion cracking at '

the tube support plate intersections.

l 3

A total of two tubes were pulled, one from each SG 2 and SG 3 for the j implementation of the voltage based alternate plugging criteria.

l This report fulfills the reporting requirements of SON Technical Specification  ;

j~ section 4.4.5.5.b for report results of SG inservice inspection. Table 1 indicates i 3 the number and extent of tubes examined. Table 2 lists the location and percent  ;

3 of wall penetration or degradation call for each indication. This table also '

l identifies the tubes plugged during the refueling outage. This report also fulfills ,

the report requirements of SON Technical Specification change 95-23  ;

commitment to provide results, distributions and evaluations within 90 days of the unit restart.

l l

l i

I w

SG TUBE INSERVICE INSPECTION SCOPE AND RESULTS The SQN SG tube Inservice inspection (ISI) initial sample for bobbin coil probe inspection was 100% of the tubes full length in each SG (except SGs 1 and 2, where approximately 17.5% of the cold leg in rows 1 through 10 from the 7* cold leg support to the cold leg tube end were not examined). The bobbin coil exams were expanded to full length of all tubes due to the detection of outside diameter stress corrosion cracking (ODSCC) detected at cold leg tube support plates.

The initial sample in all four SGs for rotating pancake coil (RPC) inspection at dented tube support plate (TSP) intersections (>5 volts by bobbin coil) was 100% of the affected hot leg TSPs. Due to the detection of ODSCC in the cold leg, RPC inspection was expanded to cold leg dented TSPs (>5 volts by bobbin coil). The initial sample for row 1 and 2 U-bend examination with RPC was 20 percent in each SG. Due to the detection of PWSCC in row 1 U-bends 100% of row 1 tubes were examined in all SGs and 100% of the row 2 U-bends were inspected in SGs 2,3 and 4. The initial sample for the rotating pancake coil examination of the WEXTEX transition region was approximately 48 percent of the hotleg tubes in each SG. Due to the detection of expansion transition primary water stress corrosion cracking (PWSCC), the RPC examination scope was expanded to 100% in SG 2, and 55% in SGs 3 and 4.

Table 1 summarizes the SON U2C7 eddy current testing inservice inspection exams and summarizes the results of exams conducted. Table 2, Steam Generator Tubing inservice inspection Resolution of Defective Tubes and All Service induced Wall Loss Indications, for the SON U2C7 Outage, provides a summary of the tube damage detected and a characterization of the damage morphology.

The SG tube degradation detected were 1) Top-of-tubesheet (TTS) PWSCC,2)

Outside Diameter Stress Corrosion Cracking (ODSCC) at non dented TSP intersections,3) Low Row U-bend PWSCC,5) Anti-Vibration Bar (AVB) Wear, and 6) Cold Leg Wastage. TTS RPC exams detected axial PWSCC located in the central region of the tube bundle where WEXTEX degradation is most likely due to high tube temperatures at the top of the tubesheet and exasperated by sludge deposits creating an insulating affect. No circumferential PWSCC was detected during these inspections.

ODSCC was detected at non-dented intersections during the Unit 2 Cycle 7 outage and Alternate Plugging Criteria was implemented. A total of 367

. indications were identified in a total of 344 tubes and 342 tubes were left in service. ODSCC was detected in the cold leg of the SQN SGs, which instigated a tube pull in SG 2 from the cold leg to verify the eddy current signals are stress corrosion cracking. Due to the detection of indications of TSP ODSCC in the cold leg RPC inspections were performed on cold leg wastage indications to 4

c _. __

verify the indications were not crack like. ODSCC is due to a caustic tube support plate crevice environment, where impurities concentrate to initiate axial stress corrosion cracking. A detailed report containing the 90 day reporting criteria is discussed later in this report.

Low row U-bend PWSCC was detected with RPC examinations during the Unit 2 Cycle 7 outage. Seventeen tubes were removed from service. Historical data review of these indications was performed. It was determined that non-magnetically bias probes were used during the Unit 2 Cycle 6 inspection. All the row 1 indications detected during the Unit 2 Cycle 7 inspection were affected by permeability changes in the tubing which coincided with the flaw location in the previous inspection. The one row 2 indication detected during the Unit 2 Cycle 7 outage was not characterized as a crack-like indication, but was conservatively plugged.

There were a number of freespan indications identified by bobbin coil (Distorted Bobbin Coil Signals) in all four SGs that indicated a percent wall loss. All of these indications were examined by RPC and no crack-like indications were detected.

Minor AVB wear and cold leg wastage was detected with the bobbin coil examinations. Four tubes were plugged for AVB wear and three tubes were

- plugged for coldlag wastage. These results are identified in Table 1.

9 4

5

TABLE 1 l

SUMMARY

OF SEQUOYAH UNIT 2 CYCLE 7 SG EDDY CURRENT INSPECTION / TUBE PLUGGING RESULTS l

EDDY CURRENT EXAM TYPE S/G 1 S/G 2 S/G 3 S/G 4 Totals Full-length bobbin coil 3363 3324 3350 3377 13414 i Partial-length bobbin coil 0 0 0 0 0 l l Support plate MRPC 85 51 70 25 231 Freespan MRPC 25 16 19 128 188 l Top of tubesheet MRPC 1654 3324 1867 1879 8724 l U-Bend MRPC 98 166 174 188 626 TOTAL EXAMS COMPLETED 5225 6881 5480 5597 23183 INDICATIONS (TUBES) S/G 1 S/G 2 S/G 3 S/G 4 Totals Defects (>=40% wals loss)

HTS PWSCC 0 9 4 2 15 COLD LEG WASTAGE 1 1 1 0 3 U-BEND PWSCC 0 6 7 4 17 AVB WEAR 2 2 0 0 4 Dogradation (>=20% and <40% wallloss and APC indications) l DIST BC SIGNAL 4 7 13 7 31 l COLD LEG WASTAGE 2 9 4 3 18 l FLOW LANE BLOCKING WEAR 0 0 0 1 1 AVB WEAR 8 16 7 2 33 PI (APC) OD CORROSlON (Note 1) 43 52 88 161 344 ImperfGCtions (<20% wellloss)

COLD LEG WASTAGE O 5 4 4 13 AVB WEAR 2 6 2 6 16 MANUFACTURING FLAWS 0 0 0 0 0 PLUGGING STATUS S/G 1 S/G 2 S/G 3 S/G 4 Totals Previously Plugged (as of U2C6) 25 64 38 11 138 Plugged Cycle 7 HTS PWSCC 0 9 4 2 15 C/L WASTAGE 1 1 1 0 3 U-BEND PWSCC 0 6 7 4 17 OD TSP CORROSION (pulled tubes) 0 1 1 0 2 AVB WEAR 2 2 0 0 4 TOTAL TUBES PLUGGED 28 83 51 17 179 Note (1) SQN Unit 2 Technical Specification Change 95-23 implemented an Alternate Plugging Criteria which allows TSP ODSCC indications to remain in service when less than 2 volts amphtude (bobbin coil).

6 l

I TABLE 2 Resolution of Defective Tubes and All Service-induced Wall Loss Indications j Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 l SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION INITIAL SAMPLE 1 2 70 Pl H02+.14 ODSCC TSP (1) 1 2 75 PI H02+.09 ODSCC TSP (1) 1 3 34 Pl H01+.06 ODSCC TSP (1) 1 5 26 Pl H02+.11 ODSCC TSP (1) 1 5 46 Pl H01 +.00 ODSCC TSP (1) 1 8 31 <40 HTS +1.25 DIST. BC SIG. (1) 1 8 32 <40 HTS +1.22 DIST. BC SIG. (1) 1 9 32 <40 HTS +1.56 DIST. BC StG. (1) 1 9 39 PI H01 +.08 ODSCC TSP (1) 1 10 18 Pt C01.08 ODSCC TSP (1) 1 11 61 Pl H02+.17 ODSCC TSP (1)-

1 13 62 Pl H05+.05 ODSCC TSP (1) 1 15 28 Pl H01 +.05 ODSCC TSP (1) 1 15 38 <40 HTS +1.02 DIST. BC StG. (1) 1 17 50 Pl H05+.13 ODSCC TSP (1) 1 17 82 PI H05+.08 ODSCC TSP (1) 1 19 38 29 AV2+.14 AVB WEAR (1) 1 19 38 17 AV3+.00 AVB WEAR (1) 1 20 58 Pl H01 +.17 ODSCC TSP (1) 1 25 28 Pl C07.05 ODSCC TSP (1) l 1 26 15 PI H02+.08 ODSCC TSP (1)  !

1 26 15 PI H02+.14 ODSCC TSP (1) 1 27 31 17 AV2+.03 AVB WEAR (1) 1 27 31 17 AV3 .03 AVB WEAR (1) 1 27 48 Pl H02+.11 ODSCC TSP (1) 1 27 64 Pl H04+.06 ODSCC TSP (1) 1 28 28 PI H04+.11 ODSCC TSP (1) 1 28 45 Pl H02+.05 ODSCC TSP (1) 1 29 13 28 AV2+.00 AVB WEAR (1)

'1 29 52 PI H02+.05 ODSCC TSP (1) 1 29 63 17 AV1 +.00 AVB WEAR PLUG 1 29 63 25 AV2+.00 AVB WEAR PLUG 1 29 63 41 AV3+.00 AVB WEAR PLUG 1 30 24 Pi C04.14 ODSCC TSP (1) 1 30 25 Pl C06.03 ODSCC TSP (1) 7

TABLE 2 l

1 Resolution of Defective Tubes and All Service-induced Wall Loss indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 1 30 80 Pl H06+ 11 ODSCC TSP (1) 1 30 83 PI H05+.00 ODSCC TSP (1) l l 1 30 83 PI H06+.20 ODSCC TSP (1) 1 31 82 PI H05+.17 ODSCC TSP (1) 1 32 64 20 AV2+.19 AVB WEAR (1) 1 32 64 24 AV3+.03 AVB WEAR (1) j 1 32 64 18 AV4+.00 AVB WEAR (1) l 1 32 68 PI H01 +.08 ODSCC TSP (1) l 1 32 79 PI H05+.14 ODSCC TSP (1) i 1 32 79 Pl H06+ 14 ODSCC TSP (1) 1 33 51 30 AV2+.00 AVB WEAR (1) I l 1 33 51 21 AV3+.00 AVB WEAR (1) 1 33 57 38 AV2+.00 AVB WEAR PLUG l l 1 33 57 43 AV3+.00 AVB WEAR PLUG I 1 33 59 22 AV1+.77 AVB WEAR (1) 1 33 59 28 AV2+.58 AVB WEAR (1) I 1 33 59 24 AV2.55 AVB WEAR (1) 1 33 59 32 AV3 .06 AVB WEAR (1) ,

1 33 59 22 AV4+.97 AVB WEAR (1) 1 34 19 31 C01 +.19 C/L WASTAGE (1) 1 34 23 PI H01+.11 ODSCC TSP (1) 1 34 32 PI H05+.19 ODSCC TSP (1) 1 34 53 38 AV2+.00 AVB WEAR (1) l 1 34 53 34 AV3+.00 AVB WEAR (1) l 1 34 79 PI H05+.19 ODSCC TSP (1) 1 35 30 10 AV2 .11 AVB WEAR (1) 1 35 30 PI H01 +.08 ODSCC TSP (1) 1 36 62 Pl H02+.11 ODSCC TSP (1) 1 36 66 24 AV3+.00 AVB WEAR (1) 1 37 62 20 AV2 .06 AVB WEAR (1) 1 37 62 30 AV3 .06 AVB WEAR (1) 1 38 65 PI H04+.08 ODSCC TSP (1) 1 40 26 Pl H05+.14 ODSCC TSP (1) 1 40 69 Pl H01+.05 ODSCC TSP (1) 8 i

l TABLE 2 1

Resolution of Defective Tubes and All Service-Induced Wall Loss indications .

1 Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 1 42 34 PI H01+.19 ODSCC TSP (1) 1 44 34 21 C01 +.00 C/L WASTAGE (1) 1 44 36 Pl H01+.16 ODSCC TSP (1) 1 44 60 Pl H05+.11 ODSCC TSP (1) l 1 46 44 Pl CO2.03 ODSCC TSP (1) 1 46 49 66 CO2.05 C/L WASTAGE PLUG This sample's results have been classified as Category C-2 l

Cold Leg Bobbin Coil Expansion 1 3 77 Pi CO2+.00 ODSCC TSP (1) 1 6 9 Pl C01+.03 ODSCC TSP (1) 1 7 9 Pi C01.05 ODSCC TSP (1) 1 9 8 Pi C01.05 ODSCC TSP (1)

This sample's results have been classified as Category C-2 (1) Retest Future Outage (2) None Required 9

TABLE 2 Resolution of Defective Tubes and All Service Induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02 Jul-96 SG ROW COL IND LOCATION CHARACTERlZATION RESOLUTION INITIAL SAMPLE 2 1 23 SAI H07+2.71 PWSCC U-BEND PLUG 2 1 33 sal H07+2.63 PWSCC U-BEND PLUG 2 1 34 MAI H07+2.60 PWSCC U-BEND PLUG 2 1 40 mal H07+2.67 PWSCC U-BEND PLUG 2 1 48 MAI H07+7.23 PWSCC U-BEND PLUG 2 1 48 MAI H07+7.28 PWSCC U-BEND PLUG sal 2 2 21 H07+7.71 PWSCC U-BEND PLUG 2 2 83 Pl H01+.03 ODSCC TSP (1) ,

2 2 85 PI H01+.06 ODSCC TSP (1) 2 3 11 90 HTS.64 PWSCC HTS PLUG l 2 3 11 SAI HTS-1.09 PWSCC HTS PLUG 2 3 42 Pl H02.06 ODSCC TSP (1) 2 3 72 PI H01+.08 ODSCC TSP (1) 2 4 2 Pl C07+.00 ODSCC TSP (1) 2 4 26 PI H02.03 ODSCC TSP (1) 2 4 69 SAI HTS-1.94 PWSCC HTS PLUG 2 4 69 SAI HTS-2.39 PWSCC HTS PLUG 2 5 54 sal HTS.82 PWSCC HTS PLUG l 2 6 3 Pl H01+.00 ODSCC TSP (1)

2 6 43 PI H02+.08 ODSCC TSP (1) 2 6 78 sal HTS-1.42 PWSCC HTS PLUG I 2 6 93 28 C01 +.14 C/L WASTAGE (1) 2 7 4 Pl H01 +.03 ODSCC TSP (1) 2 7 4 Pl H02+.08 ODSCC TSP (1) 2 7 20 Pl H04+.14 ODSCC TSP (1) 2 7 50 SAI HTS.58 PWSCC HTS PLUG 2 8 61 PI H02.25 ODSCC TSP (1) 2 9 57 Pl H02.06 ODSCC TSP (1) 2 9 72 PI H02.33 ODSCC TSP (1) 2 10 8 PI H05+.06 ODSCC TSP (1) 2 10 39 Pl H01.08 ODSCC TSP (1) 2 10 56 sal HTS-1.15 PWSCC HTS PLUG 10

, TABLE 2 Resolution of Defective Tubes and All l l Service Induced Wall Loss Indications l Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 2 11 39 SAI HTS.52 PWSCC HTS PLUG 2 11 55 <40 HTS +1.82 DIST. BC SIG. (1) l 2 12 35 Pl H01 +.00 ODSCC TSP (1)

)

2 12 63 <40 HTS +2.18 DIST. BC SIG. (1) 2 12 92 34 C01.05 C/L WASTAGE (1) l 2 13 15 Pl H04+.00 ODSCC TSP (1) 2 13 15 Pl H05.05 ODSCC TSP (1) 2 14 42 <40 HTS +1.98 DIST. BC SIG. (1) 2 14 48 Pl H01+.05 ODSCC TSP (1) 2 14 54 <40 HTS +1.08 DIST. BC SIG. (1) 2 15 33 Pl H01+.08 ODSCC TSP (1) 2 15 54 PI H02.03 ODSCC TSP (1) i 2 15 54 <40 HTS +2.43 DIST. BC SIG. (1) l 2 15 89 Pl H01 +.05 ODSCC TSP (1)  !

2 17 28 15 AV1+.00 AVB WEAR (1) 2 17 28 29 AV3 .21 AVB WEAR (1) l 2 17 64 19 AV1 +.50 AVB WEAR (1) 2 17 64 28 AV2.73 AVB WEAR (1) 2 17 64 21 AV3.55 AVB WEAR (1) 2 18 42 19 AV2+.00 AVB WEAR (1) I 2 18 72 19 AV3+.00 AVB WEAR (1) 2 18 89 22 C01+.03 C/L WASTAGE (1) 2 19 28 21 AV1.14 AVB WEAR (1) 2 20 34 <40 HTS +1.38 DIST. BC SIG. (1) 2 21 53 Pl H05+.03 ODSCC TSP (1) 2 22 41 23 AV2+.00 AVB WEAR (1) 2 22 73 PI H05.03 ODSCC TSP (1) 2 23 69 31 AV2+.00 AVB WEAR (1) 2 23 69 27 AV3+.00 AVB WEAR (1) 2 24 37 <40 HTS +1.32 DIST. BC SIG. (1) 2 24 61 30 AV2.08 AVB WEAR (1) 2 24 63 31 AV2+.00 AVB WEAR (1) 2 24 82 Pl H02+.08 ODSCC TSP (1) 2 24 87 Pl H01+.03 ODSCC TSP (1) 11 I

TABLE 2 Resolution of Defective Tubes and All Service-Induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION

. 2 26 21 PI H04.03 ODSCC TSP (1) 2 26 23 Pi C06+.00 ODSCC TSP (1) 2 26 70 25 AV3+.25 AVB WEAR (1) l 2 27 65 28 AV2+.00 AVB WEAR (1) 2 27 65 28 AV3+.00 AVB WEAR (1) I

] 2 27 84 Pl H01+.03 ODSCC TSP (1) l 2 28 69 PI H02+.03 ODSCC TSP (1)

{ 2 29 16 PI H01+.05 ODSCC TSP (1)

] 2 29 16 PI H02+.05 ODSCC TSP (1)

{ 2 29 32 30 AV2+.06 AVB WEAR (1) 2 29 32 23 AV3 .29 AVB WEAR (1) i 2 29 32 24 AV4 .88 AVB WEAR (1) j 2 29 37 18 AV2+.00 AVB WEAR (1)

2 29 37 17 AV3+.00 AVB WEAR (1) 2 29 39 15 AV2+.00 AVB WEAR (1)

I 2 29 39 20 AV3+.00 AVB WEAR (1)

!! 2 29 42 30 AV1.22 AVB WEAR (1)

2 29 42 31 AV2.17 AVB WEAR (1) l 2 29 42 39 AV3+.03 AVB WEAR (1) l 2 29 42 15 AV4 .08 AVB WEAR (1)

! 2 30 70 Pl H01+.05 ODSCC TSP (1) 2 31 17 Pl H04+.05 ODSCC TSP (1) 2 31 70 PI H01+.08 ODSCC TSP (1) 2 32 20 PI H01+.05 ODSCC TSP (1)

2 32 20 Pi H02+.03 ODSCC TSP (1) 2 32 20 Pl H03.05 ODSCC TSP (1) 2 32 54 20 AV2+.00 AVB WEAR PLUG 2 32 54 42 AV3+.00 AVB WEAR PLUG 2 32 56 22 AV1.08 AVB WEAR (1) 2 32 56 26 AV2 .14 AVB WEAR (1) 2 32 62 18 AV2+.22 AVB WEAR (1) 2 32 62 22 AV3+.00 AVB WEAR (1) 2 32 79 48 C01.27 C/L WASTAGE PLUG 2 33 49 23 AV1.17 AVB WEAR (1) 12

I TABLE 2 I

Resolution of Defective Tubes and All ,

Service-induced Wall Loss indications I Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 2 33 49 31 AV2.08 AVB WEAR (1) 2 33 49 35 AV3 .08 AVB WEAR (1) 2 33 49 17 AV4 .11 AVB WEAR (1) i 2 33 62 19 AV3+.28 AVB WEAR (1) 2 34 17 13 C01.19 C/L WASTAGE (1) 2 34 63 20 AV1+.00 AVB WEAR PLUG 2 34 63 40 AV2+.00 AVB WEAR PLUG 2 34 63 21 AV3+.00 AVB WEAR PLUG 2 35 55 Pl H02+.03 ODSCC TSP (1) 2 36 18 29 C01+.00 C/L WASTAGE (1) 2 36 42 PI H02+.05 ODSCC TSP (1) 2 36 71 PI H01 +.06 ODSCC TSP (1) 2 37 20 PI H01+.03 ODSCC TSP (1) 2 37 21 14 C01+.06 C/L WASTAGE (1) 2 38 22 24 C03+.05 C/L WASTAGE (1) 2 38 24 23 C01+.14 C/L WASTAGE (1) 2 38 43 14 AV3 .19 AVB WEAR (1) 2 38 43 17 AV4.08 AVB WEAR (1) 2 38 43 16 AV4 .13 AVB WEAR (1) 2 38 45 Pl H02+.05 ODSCC TSP (1) 2 38 45 Pl H03+.05 ODSCC TSP (1) 2 38 46 20 AV3+.00 AVB WEAR (1) 2 38 46 22 AV4+.00 AVB WEAR (1) 2 39 49 16 AV3 .22 AVB WEAR (1) 2 39 49 18 AV4 .19 AVB WEAR (1) 2 42 31 30 C01.13 C/L WASTAGE (1) 2 42 39 Pl H03+.05 ODSCC TSP (1) 2 42 64 32 C01+.25 C/L WASTAGE (1) 2 42 66 17 C01 +.14 C/L WASTAGE (1) 2 43 49 PI H02+.05 ODSCC TSP (1) 2 43 63 26 C01+.00 C/L WASTAGE (1) 2 44 33 13 C01+.13 C/L WASTAGE (1) 2 44 34 PI H01+.05 ODSCC TSP (1) 2 44 36 Pl H04+.00 ODSCC TSP (1) 13

TABLE 2 Resolution of Defective Tubes and All Service-induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul 96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 2 46 48 17 C01+.19 C/L WASTAGE (1)

This sample's results have been classified as Category C-2 I Top of Tubesheet RPC Expansion 2 13 84 SAI HTS.01 PWSCC HTS PLUG 2 18 80 SAI HTS.01 PWSCC HTS PLUG This sample's results have been classified as Category C-2 Cold Leg Bobbin Coil Expansion 2 3 25 Pl C01+.00 ODSCC TSP (1) 2 4 19 Pl C02+.03 ODSCC TSP (1) 2 4 20 Pl CO2+ 05 ODSCC TSP (1) 2 4 21 Pl CO2+.03 ODSCC TSP (1) 2 4 23 Pi CO2+.00 ODSCC TSP (pull) PLUG (tube pull) 2 4 24 Pl C02+.08 ODSCC TSP (1) 2 6 10 Pl C02+.08 ODSCC TSP (1) 2 7 22 Pl C01.03 ODSCC TSP (1) 2 8 8 Pl C04.03 ODSCC TSP (1)

This sample's results have been classified as Category C-2 (1) Retest Future outage (2) None Required l

1 14

TABLE 2 l Resolution of Defective Tubes and All Service-Induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION INITIAL SAMPLE l

1 3 1 2 SAI H07+7.74 PWSCC U-BEND PLUG 3 1 27 SAI H07+3.69 PWSCC U-BEND PLUG 3 1 26 SAI H07+4.28 PWSCC U-BEND PLUG 3 1 29 MAI H07+3.85 PWSCC U-BEND PLUG l 3 1 38 sal H07+6.41 PWSCC U-BEND PLUG

! 3 1 50 SAI H07+2.67 PWSCC U-BEND PLUG l

3 1 59 SAI H07+7.48 PWSCC U-BEND PLUG 3 2 16 PI H01.03 ODSCC TSP (1) l 3 2 39 PI H02.05 ODSCC TSP (1) 3 2 44 Pi C01 +.00 ODSCC TSP (1) i 3 2 83 PI H06+.06 ODSCC TSP (1) l 3 3 2 Pl H01+.00 ODSCC TSP (1) l 3 4 50 PI H05+.03 ODSCC TSP (1) 3 4 82 Pl H02.03 ODSCC TSP (1) 3 5 1 22 C01+.66 C/L WASTAGE (1) 3 5 1 Pl H02.03 ODSCC TSP (1) 3 5 6 Pl C01 +.05 ODSCC TSP (1) 3 5 8 Pl C01+.03 ODSCC TSP (1) 3 5 17 Pl H02.05 ODSCC TSP (1) 3 5 19 Pl H01+.00 ODSCC TSP (1) 3 5 45 <40 HTS +1.23 DIST. BC SIG. (1) 3 5 51 Pl H05+.00 ODSCC TSP (1) 3 6 48 PI H01+.03 ODSCC TSP (1) 3 7 71 PI H02.03 ODSCC TSP (1) 3 7- 72 Pl H02+.00 ODSCC TSP (1) 3 8 2 56 C01+.11 C/L WASTAGE PLUG 3 8 14 96 HTS-1.36 PWSCC HTS PLUG 3 8 14 SAI HTS-1.69 PWSCC HTS PLUG 3 8 56 Pl H01 +.08 ODSCC TSP (1) l 3 8 57 PI H04.03 ODSCC TSP (1) 3 8 58 PI H01 +.03 ODSCC TSP (1) j 3 8 60 sal H01+.00 ODSCC TSP (pull) PLUG (tube pull) 15 l

1

i TABLE 2 Resolution of Defective Tubes and All Service-Induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 3 8 60 Pl H01.03 ODSCC TSP (pull) PLUG (tube pull) 3 8 69 PI H01+.03 ODSCC TSP (1) 3 9 2 Pi H01.08 ODSCC TSP (1) 3 9 14 Pl C01+.03 ODSCC TSP (1) 3 9 33 <40 HTS +1.55 DIST. BC SIG. (1) 3 9 36 <40 HTS +1.64 DIST. BC SIG. (1) 3 9 42 <40 HTS +1.28 DIST. BC SIG. (1) 3 9 48 Pl H01+.03 ODSCC TSP (1) 3 9 51 Pl H01 +.00 ODSCC TSP (1) 3 9 68 <40 HTS +1.48 DIST. BC SIG. (1) 3 10 2 Pl H04+.03 ODSCC TSP (1) 3 10 5 Pl H01 +.14 ODSCC TSP (1) 3 10 20 Pl C01.03 ODSCC TSP (1) 3 10 58 <40 HTS +1.32 DIST. BC SIG. (1) 3 10 60 <40 HTS +1.39 DIST. BC SIG. (1) 3 10 61 <40 HTS +1.57 DIST. BC SIG. (1) 3 10 62 Pl H01+.00 ODSCC TSP (1) 3 10 93 19 C03+.00 C/L WASTAGE (1) 3 10 93 19 C03+.05 C/L WASTAGE (1) 3 11 2 32 C01.08 C/L WASTAGE (1) 3 11 16 Pl H06+.03 ODSCC TSP (1) 3 12 12 Pi H01 +.06 ODSCC TSP (1) 3 12 46 <40 HTS +1.17 DIST. BC SIG. (1) 3 12 50 SAI HTS-1.37 PWSCC HTS PLUG 3 13 3 PI H02+.03 ODSCC TSP (1) 3 13 11 Pl C07+.05 ODSCC TSP (1) 3 13 31 Pl H01+.03 ODSCC TSP (1) 3 13 46 <40 HTS +1.47 DIST. BC SIG. (1) 3 13 53 Pl H01 +.00 ODSCC TSP (1) 3 14 3 13 C01.19 C/L WASTAGE (1) 3 14 14 Pl H01+.19 ODSCC TSP (1) 3 14 20 Pl H02.03 ODSCC TSP (1) 3 14 56 Pl H02+.06 ODSCC TSP (1) 3 15 3 Pl H01 +.05 ODSCC TSP (1) 16

TABLE 2 Resolution of Defective Tubes and All Service-induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02 Jul 96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 3 15 3 Pl H02+.05 ODSCC TSP (1) 3 15 15 PI H01+.08 ODSCC TSP (1) 3 16 4 Pl H02+.05 ODSCC TSP (1) 3 16 54 Pl H01+.08 ODSCC TSP (1) 3 16 68 SAI HTS-1.76 PWSCC HTS PLUG 3 16 81 Pl C01+.03 ODSCC TSP (1) 3 17 22 PI H01+.14 ODSCC TSP (1) 3 17 81 Pl C01+.05 ODSCC TSP (1) 3 18 18 Pl H01+.05 ODSCC TSP (1) 3 18 21 PI H01 +.11 ODSCC TSP (1) 3 18 30 20 AV2+.00 AVB WEAR (1) 3 18 35 Pl H01 +.08 ODSCC TSP (1) 3 18 38 Pl H01.03 ODSCC TSP (1) 3 18 49 Pl H01+.03 ODSCC TSP (1) 3 18 65 <40 HTS +1.27 DIST. BC SIG. (1) 3 19 14 Pl H02+ 19 ODSCC TSP (1) 3 19 64 27 AV2+.00 AVB WEAR (1) 3 19 79 Pl H02+.05 ODSCC TSP (1) 3 20 12 Pl H01+.11 ODSCC TSP (1) 3 20 28 Pi H01+.22 ODSCC TSP (1) 3 21 24 PI H01 +.08 ODSCC TSP (1) 3 21 51 <40 HTS +1.39 DIST. BC SIG. (1) 3 21 84 Pl H04+.03 ODSCC TSP (1) 3 22 88 PI H03+.14 ODSCC TSP (1) 3 23 33 SAI HTS-1.21 PWSCC HTS PLUG 3 24 12 PI H01+.05 ODSCC TSP (1) 3 24 29 PI H01+.05 ODSCC TSP (1) 3 25 9 Pl C01+.03 ODSCC TSP (1) 3 26 9 PI H01 +.05 ODSCC TSP (1) 3 26 35 Pl H01+.03 ODSCC TSP (1) 3 26 80 Pl H05+.05 ODSCC TSP (1) 3 27 26 Pl H01+.14 ODSCC TSP (1) 3 27 26 PI H02+.11 ODSCC TSP (1) 3 27 30 Pl H02+.08 ODSCC TSP (1) 17

TABLE 2 Resolution of Defective Tubes and All Service-Induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 3 27 50 <40 HTS +.87 DIST. BC SIG. (1) 3 28 45 17 AV1+.00 AVB WEAR (1) l 3 28 45 18 AV2+.00 AVB WEAR (1) l 3 28 45 20 AV3+.00 AVB WEAR (1) 3 29 81 PI H02+.16 ODSCC TSP (1) 3 30 23 Pl H01 +.14 ODSCC TSP (1) 3 31 81 Pl H05+.08 ODSCC TSP (1) 3 32 24 25 AV1+.00 AVB WEAR (1) 3 32 40 19 AV3+.00 AVB WEAR (1) ,

3 32 78 PI H04+.03 ODSCC TSP (1) l 3 32 78 PI H05+.06 ODSCC TSP (1) )

3 32 79 PI H05+.08 ODSCC TSP (1) 3 32 79 PI H06+.03 ODSCC TSP (1) 3 33 21 PI H01+.16 ODSCC TSP (1) 3 33 25 Pl H04+.08 ODSCC TSP (1) 3 33 40 Pl H01+.05 ODSCC TSP (1) 3 33 61 13 AV1+.00 AVB WEAR (1) 3 33 61 15 AV3+.00 AVB WEAR (1) 3 33 79 30 C01.08 C/L WASTAGE (1) 3 34 16 15 C01.19 C/L WASTAGE (1) 3 34 19 PI H02.03 ODSCC TSP (1) 3 34 21 Pl H01+.14 ODSCC TSP (1) 3 34 43 32 AV2+.00 AVB WEAR (1) 3 34 43 38 AV3+.00 AVB WEAR (1) 3 34 43 21 AV4+.00 AVB WEAR (1) 3 34 72 PI H02+ 05 ODSCC TSP (1) 3 34 78 22 C01+.08 C/L WASTAGE (1) 3 35 17 19 C01.47 C/L WASTAGE (1) 3 35 38 PI C02+.03 ODSCC TSP (1) 3 35 39 25 AV1.08 AVB WEAR (1) 3 35 76 PI H05+.00 ODSCC TSP (1) 3 35 76 Pl H06+.00 ODSCC TSP (1) l 3 37 33 PI H04+.03 ODSCC TSP (1) i 3 38 22 PI H01+.14 ODSCC TSP (1) 18

TABLE 2 Resolution of Defective Tubes and All I

Service-Induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 3 38 40 18 AV3+.00 AVB WEAR (1) 3 38 40 20 AV4+.00 AVB 'NEAR (1) 3 39 68 Pl H04+.08 ODSCC TSP (1) 3 40 24 Pl H02.03 ODSCC TSP (1) 3 40 25 Pl H01+.06 ODSCC TSP (1) 3 40 64 PI H03+.03 ODSCC TSP (1)

G 42 33 Pl H01+.00 ODSCC TSP (1)  ;

3 43 44 PI H04+.08 ODSCC TSP (1) I 3 44 34 PI H01+.05 ODSCC TSP (1) l 3 46 47 PI H05.03 ODSCC TSP (1)

This sample's results have been classified as Category C-2  !

Top of Tubesheet RPC Expansion No Indications This sample's results have been clF.ssified as Category C-1 (1) Retest Future Outage (2) None Required 19

TABLE 2 Resolution of Defective Tubes and All Service-Induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION INITIAL SAMPLE 4 1 15 sal H07+6.90 PWSCC U-BEND PLUG 4 1 17 SAI H07+6.09 PWSCC U-BEND PLUG 4 1 17 SAI H07+6.77 PWSCC U-BEND PLUG 4 1 19 sal H07+6.64 PWSCC U-BEND PLUG 4 1 23 SO! H07+6.48 P'NSCC U-BEND PLUG 4 1 94 <40 H02.38 DIST. BC SIG. (1) 4 1 94 31 HTS +17.56 FLBD WEAR (1) 4 2 9 Pl C04.03 ODSCC TSP (1) 4 2 13 SAI HTS.02 PWSCC HTS PLUG 4 2 15 Pi C06+.03 ODSCC TSP (1) 4 2 37 Pl H02+.03 ODSCC TSP (1) 4 2 40 Pl H01 +.05 ODSCC TSP (1) 4 2 53 PI H01 +.11 ODSCC TSP (1) 4 2 55 PI H01 +.11 ODSCC TSP (1) 4 2 58 Pl H02.03 ODSCC TSP (1) 4 2 61 Pl H02+.08 ODSCC TSP (1) 4 2 67 PI H01+.05 ODSCC TSP (1) 4 2 76 PI H01+.05 ODSCC TSP (1) 4 3 8 PI H02+.00 ODSCC TSP (1) 4 3 26 PI C02.03 ODSCC TSP (1) 4 3 71 Pl H02.03 ODSCC TSP (1) 4 3 72 PI H01.03 ODSCC TSP (1) 4 4 22 PI H02+.08 ODSCC TSP (1) 4 4 87 Pl H01+.03 ODSCC TSP (1) 4 4 89 PI H03+.03 ODSCC TSP (1) 4 4 91 Pl H01+.00 ODSCC TSP (1) 4 5 1 Pl H01+.08 ODSCC TSP (1) 4 5 12 PI H02+.00 ODSCC TSP (1) 4 5 42 PI H01+.03 ODSCC TSP (1) 4 5 46 Pl H01.05 ODSCC TSP (1) 4 5 51 PI H06+.00 ODSCC TSP (1) 4 5 53 PI H01 +.11 ODSCC TSP (1) 20

TABLE 2 Resolution of Defective Tubes and All Service-Induced Wall Loss Indications Outage: SON Unit 2 Cycle 7 Date: 02-Jul 96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 4 5 84 Pl H01+.08 ODSCC TSP (1) 4 5 91 Pl H01+.00 ODSCC TSP (1) 4 6 37 PI H01+.05 ODSCC TSP (1) 4 6 45 PI H01+.05 ODSCC TSP (1)

! 4 6 84 Pl H01+.08 ODSCC TSP (1) l l 4 7 50 SAI HTS.10 PWSCC HTS PLUG l 4 7 51 PI H01+.05 ODSCC TSP (1) 4 8 3 Pl H03+.03 ODSCC TSP (1) 4 8 8 Pl H02.03 ODSCC TSP (1) 4 8 35 Pl H01.03 ODSCC TSP (1) 4 8 37 Pl H01 +.08 ODSCC TSP (1) 4 8 42 PI H01+.03 ODSCC TSP (1) 4 8 52 PI H01+.00 ODSCC TSP (1) 4 8 53 PI H01+.05 ODSCC TSP (1) 4 8 55 Pl H01+.11 ODSCC TSP (1) 4 8 59 PI H01+.08 ODSCC TSP (1) i 4 8 60 Pl H01.03 ODSCC TSP (1) 4 8 80 PI H01.03 ODSCC TSP (1) 4 8 85 Pl H01.03 ODSCC TSP (1) 4 8 86 Pl H01.03 ODSCC TSP (1) 4 8 92 Pl H01 +.00 ODSCC TSP (1) 4 8 92 Pl H02+.03 ODSCC TSP (1) 4 9 38 Pl H01+.00 ODSCC TSP (1) 4 9 43 PI H01 +.00 ODSCC TSP (1) 4 9 50 PI H01 +.11 ODSCC TSP (1) 4 9 74 Pl H05+.00 ODSCC TSP (1) 4 11 3 14 C01.17 C/L WASTAGE (1) 4 11 53 <40 HTS +.99 DIST. BC SIG. (1) 4 11 65 <40 HTS +2.04 DIST. BC SIG. (1) 4 11 67 <40 HTS +1.63 DIST. BC SIG. (1) 4 11 85 PI H05+.16 ODSCC TSP (1) 4 12 26 PI H02+.11 ODSCC TSP (1) 4 12 32 PI H01 +.11 ODSCC TSP (1) 4 12 41 Pl H01 +.14 ODSCC TSP (1) 21

TABLE 2 )

l Resolution of Defective Tubes and All Service-induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul 96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 4 12 43 PI H01+.16 ODSCC TSP (1) 4 12 45 PI H01+.11 ODSCC TSP (1) 4 12 59 Pl H01+.11 ODSCC TSP (1) 4 12 61 Pl H01 +.11 ODSCC TSP (1) 4 12 64 Pl H01+.05 ODSCC TSP (1) 4 12 67 <40 HTS +.94 DIST. BC SIG. (1) 4 12 67 <40 HTS +1.50 DIST. BC SIG. (1) 4 12 72 PI H01 +.00 ODSCC TSP (1) 4 12 83 PI H01 +.08 ODSCC TSP (1) 4 13 38 PI H01+.14 ODSCC TSP (1) 4 13 45 PI H01+.11 ODSCC TSP (1) 4 13 47 PI H03+.14 ODSCC TSP (1) 4 13 48 Pl H01+.08 ODSCC TSP (1) 4 13 52 Pl H01+.16 ODSCC TSP (1) 4 13 53 PI H01+.11 ODSCC TSP (1) 4 14 54 <40 HTS +1.07 DIST. BC SIG. (1) 4 14 57 PI H01+.06 ODSCC TSP (1) 4 14 88 Pl H01 +.11 ODSCC TSP (1) 4 14 92 Pl H01+.08 ODSCC TSP (1) 4 15 48 Pl H01+.05 ODSCC TSP (1) 4 15 50 PI H01+.03 ODSCC TSP (1) 4 15 51 PI ' H01 +.11 ODSCC TSP (1) 4 15 52 Pl H01+.11 ODSCC TSP (1) 4 15 53 PI H01+.06 ODSCC TSP (1) 4 15 54 Pl H01+.22 ODSCC TSP (1) 4 15 57 <40 HTS +1.73 DIST. BC SIG. (1) 4 15 62 Pl H01 +.08 ODSCC TSP (1) 4 15 65 PI H01+.17 ODSCC TSP (1) 4 17 20 Pl H01 +.22 ODSCC TSP (1) 4 17 27 Pl H01 +.22 ODSCC TSP (1) 4 17 55 PI H01 +.14 ODSCC TSP (1) 4 17 87 PI H01 +.08 ODSCC TSP (1) 4 18 6 PI H02+.11 ODSCC TSP (1) 4 18 32 Pl C05.11 ODSCC TSP (1) 22

l .

TABLE 2 ,

Resolution of Defective Tubes and All Service-induced Wall Loss indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 4 18 33 PI H05+.14 ODSCC TSP (1) 4 18 54 Pl H01 +.08 ODSCC TSP (1) 4 18 61 PI H01+.08 ODSCC TSP (1) 4 20 45 PI H01+.08 ODSCC TSP (1) 4 20 47 Pl H02+.08 ODSCC TSP (1) 4 20 48 Pl H01+.03 ODSCC TSP (1) 4 20 50 Pl H01+.08 ODSCC TSP (1) l 4 20 51 PI H01+.05 ODSCC TSP (1)

I 4 20 56 PI H01 +.16 ODSCC TSP (1)

]

4 20 58 Pl H01+.08 ODSCC TSP (1) 4 20 59 Pl H01+.05 ODSCC TSP (1) 4 20 60 Pl H01 +.14 ODSCC TSP (1) 4 20 63 Pl H01 +.08 ODSCC TSP (1) 4 20 69 Pl H01+.11 ODSCC TSP (1) 4 21 6 Pl H04+.08 ODSCC TSP (1) 4 21 15 Pl H06+.00 ODSCC TSP (1) 4 21 19 Pl C05.08 ODSCC TSP (1) 4 22 15 PI H02+.08 ODSCC TSP (1) 4 22 17 Pl C04.08 ODSCC TSP (1) 4 22 17 Pl C05.14 ODSCC TSP (1) 4 22 17 Pl H02+.14 ODSCC TSP (1) 4 22 59 PI H01+.05 ODSCC TSP (1) 4 22 70 Pl H01+.14 ODSCC TSP (1) 4 22 71 PI H03+.14 ODSCC TSP (1) 4 23 64 PI H01+.11 ODSCC TSP (1) 4 23 65 PI H02+.14 ODSCC TSP (1) 4 23 69 PI H02+.25 ODSCC TSP (1) 4 23 71 Pl H01 +.11 ODSCC TSP (1) 4 23 73 Pl H02+.11 ODSCC TSP (1) 4 24 22 PI H03+ 09 ODSCC TSP (1) 4 25 57 PI H02+.05 ODSCC TSP (1) 4 25 67 Pl H04+.06 ODSCC TSP (1) 4 26 15 Pl H02+.08 ODSCC TSP (1) 4 26 69 PI H01 +.11 ODSCC TSP (1) 23

TABLE 2 i

Resolution of Defective Tubes and All Service-Induced Wall Loss Indications l Outage: SQN Unit 2 Cycle 7 Date: 02-Jul-96 l

SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION l 4 26 71 Pl H01+.11 ODSCC TSP (1) i 4 26 86 PI H02+.11 ODSCC TSP (1) 4 27 63 Pl H01+.08 ODSCC TSP (1) 4 27 70 Pl H01+.11 ODSCC TSP (1) 4 27 71 Pl H01 +.11 ODSCC TSP (1) 4 27 72 PI H02+.08 ODSCC TSP (1) 4 27 72 PI H03+.11 ODSCC TSP (1) 4 27 75 Pl H02+.16 ODSCC TSP (1) 4 27 76 Pl H01+.03 ODSCC TSP (1) j 4 27 77 Pl H01 +.11 ODSCC TSP (1) 4 27 77 Pl HO?+.14 ODSCC TSP (1) j 4 27 77 Pl H03+.16 ODSCC TSP (1) I 4 27 78 PI H02+.08 ODSCC TSP (1) 4 27 79 PI H02+.16 ODSCC TSP (1) <

4 27 80 PI H02+.08 ODSCC TSP (1) ,

4 27 83 Pl H01+.11 ODSCC TSP (1) 4 28 18 Pl H02+.06 ODSCC TSP (1) 4 28 62 Pl H02+.08 ODSCC TSP (1) 4 28 63 PI H02+.11 ODSCC TSP (1) 4 28 67 MAI H01+.00 ODSCC TSP (1) 4 28 67 MAI H01+.00 ODSCC TSP (1) ,

4 28 67 PI H01 +.11 ODSCC TSP I (1) 4 28 67 MAI H01.07 ODSCC TSP (1) 4 28 68 PI H01 +.06 ODSCC TSP (1) 4 28 68 Pl H02+.11 ODSCC TSP (1) l 4 28 70 Pl H01+.16 ODSCC TSP (1) i 4 28 70 Pl H02+.14 ODSCC TSP (1) 4 28 72 PI H01 +.11 ODSCC TSP (1) 4 28 72 PI H02+.19 ODSCC TSP (1) 4 28 77 PI H01+.08 ODSCC TSP (1) 4 28 78 Pl H01 +.16 ODSCC TSP (1) 4 28 79 Pl H03+.16 ODSCC TSP (1) {

4 28 81 Pl H02+.08 ODSCC TSP (1) 4 29 18 Pl H07+.06 ODSCC TSP (1) l 24

i TABLE 2 i

Resolution of Defective Tubes and All Senice-induced Wall Loss Indications Outage: SQN Unit 2 Cycle 7 Date: 02-Jul 96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 4 29 51 Pl H01+.11 ODSCC TSP (1) 4 29 56 Pl H06+.22 ODSCC TSP (1) 4 29 67 21 AV1+1.54 AVB WEAR (1) 4 29 67 28 AV3+.03 AVB WEAR (1) 4 29 67 18 AV4 .14 AVB WEAR (1) 4 30 80 Pi C05.08 ODSCC TSP (1) 4 31 54 PI H01+.16 ODSCC TSP (1) 4 31 72 Pl H01 +.11 ODSCC TSP (1) 4 31 79 Pl C05 .08 ODSCC TSP (1) 4 31 82 Pl C04.05 ODSCC TSP (1) 4 32 41 12 AV2+.33 AVB WEAR (1) 4 32 41 11 AV3+.00 AVB WEAR (1) 4 32 65 Pl H02+.14 ODSCC TSP (1) 4 32 70 PI H02+.16 ODSCC TSP (1) 4 34 18 PI H06+.14 ODSCC TSP (1) 4 35 55 14 AV1+.00 AVB WEAR (1) 4 36 57 Pl H02+.22 ODSCC TSP (1) 4 36 62 Pl H02+.05 ODSCC TSP (1) 4 36 65 PI H01+.11 ODSCC TSP (1) i 4 36 68 PI H02+.11 ODSCC TSP (1) 4 37 19 11 C01.16 C/L WASTAGE (1) 4 37 62 Pl H04+.08 ODSCC TSP (1) 4 37 63 Pl H01 +.08 ODSCC TSP (1) 4 38 21 PI H06+.11 ODSCC TSP (1) 4 38 26 PI H02+.11 ODSCC TSP (1) 4 38 44 19 AV3 .11 AVB WEAR (1) 4 38 47 19 AV3+.00 AVB WEAR (1) 4 38 47 16 AV4+.00 AVB WEAR (1) i 4 38 49 17 AV3+.00 AVB WEAR (1) 4 38 52 22 AV3+.20 AVB WEAR (1) 4 36 52 26 AV4+.25 AVB WEAR (1) 4 38 65 16 AV1.28 AVB WEAR (1) 4 38 65 17 AV2 .08 AVB WEAR (1) 4 38 74 PI' H04+.08 ODSCC TSP (1) 25

TABLE 2 Resolution of Defective Tubes and All Service-Induced Wall Loss indications Outage: SQN Unit 2 Cycle 7 Date: 02 Jul-96 SG ROW COL IND LOCATION CHARACTERIZATION RESOLUTION 4 40 49 Pl H02+.11 ODSCC TSP (1) 4 43 35 15 C02+.05 C/L WASTAGE (1) 4 43 61 39 CO2.14 C/L WASTAGE (1) 4 44 58 PI H06+.11 ODSCC TSP (1) l 4 44 59 Pl H01 +.11 ODSCC TSP (1) l 4 44 61 29 C03+.22 C/L WASTAGE (1) 4 45 54 14 CO2+.08 C/L WASTAGE (1) 4 45 57 27 CO2.14 C/L WASTAGE (1)

This sample's results have been classified as Category C-2 i

Top of Tubesheet RPC Expansion l

No Indications This sample's results have been classified as Category C-1 (1) Retest Future Outage (2) None Required

(

4 26

TABLE 2 i

Location Nomenclature for SQN Notation Description HTE Tube end - hot leg HTS Top of tubesheet-hotleg H01 First support plate - hot leg H02 Second support plate - hot leg H03 Third support plate - hot leg H04 Fourth support plate - hot leg H05 Fifth support plate - hot leg H06 Sixth support plate - hot leg H07 Seventh support plate - hot leg AV1 First anti-vibration bar above H07 AV2 Second an+J-vibration bar above H07 AV3 Second anti-vibration bar above C07 AV4 First anti-vibration bar above C07 C07 Seventh support plate - cold leg C06 Sixth support plate - cold leg C05 Fifth support plate - cold leg C04 Fourth support plate - cold leg C03 Third support plate - cold leg CO2 Second support plate - cold leg C01 First support plate - cold leg CTS Top of tubesheet- cold leg CTE Tube end - cold leg Indication and Characterization Nomenclature Notation Description AVB Anti-Vibration Bar C/L Cold Leg Dist. BC Sig. Distorted Bobbin Coil Signal FLBD Flow Lane Blocking Device MAI Multiple AxialIndications ODSCC Outside Diameter Stress Corrosion Cracking Pl Potential Indication (ODSCC at TSPs)

PWSCC Primary Water Stress Corrosion Cracking SAI Single AxialIndication sol Single Oblique Indication TSP Tube Support Plate 27

ALTERNATE PLUGGING CRITERIA RESULTS .

1 A report in accordance with Technical Specification Change 95-23 commitment  !

for Alternate Plugging Criteria was prepared by Westinghouse Electric Corp. to l provide results, distributions, and evaluations within 90 days of unit restart for i the implementation of Alternate Plugging Criteria at SON Unit 2. The  !

Westinghouse report is Attachment 1.

l l

l l

i l

4 i

28

i LOW ROW U-BEND INDICATION RESULTS

, Low row U-bend PWSCC was detected with RPC examinations during the Unit 2 Cycle 7 outage. Seventeen tubes were removed from service during this inspection. Historical data review of these indications was performed to 1

determine growth rate information in support of structural integrity analysis. All the row 1 indications detected during the Unit 2 Cycle 7 inspection were affected by permeability changes in the tubing which coincided with the flaw location in the previous inspection. It was determined that non-magnetically bias probes

, were used during the Unit 2 Cycle 6 inspection. Westinghouse performed the l structural integrity analysis of the three largest indications (See Attachment 2).

TVA has reviewed the results of the analysis and concurs with the conclusion

that structural integrity was maintained during cycle 7 operation. The one row 2 s indication detected during the Unit 2 Cycle 7 outage was not believed to be

crack-like but was conservatlvely plugged.

i j I I l

Y e

l l

29 I

j

CONCLUSIONS The NDE testing completed on the SON Unit 2 SGs and plugging of defective i tubes met the Technical Specification and ASME Section XI code requirements for Inservice Inspection; therefore, each SG has been demonstrated operable.

Alternate Plugging Criteria was implemented in accordance with Technical Specification Change 95-23.

I Steam Generator Chemical Cleaning was implemented during the Unit 2 Cycle 7 outage as an ameliorative measure for ODSCC at non-dented tube support plate inter.cections to prevent future incidence of ODSCC at all tube locations.

t l

l l

l l l

\ 1 l

I i

30

j ..^. -

! Attechm: Int 1

] WESTINGHOUSE PROPRIETARY CLASS 3 l

i i SG-96 08-010 4

i i

j SEQUOYAH UNIT - 2 i CYCLE 8 ALTERNATE PLUGGING CRITERIA 1 90 DAY REPORT 4

1

August 1996 1

4 J

I 4

f 1

i i

i l1 6

Westinghouse Electric Corporation Energy Systems Business Unit l Nuclear Services Division

! P.O. Box 158 Madison, Pennsylvania 15663-0158 J

d

. o i

i

WESTINGHOUSE PROPRIETARY CLASS 3 SG-96-08 010 1

1 i

i 1

i i

l SEQUOYAH UNIT - 2 i CYCLE 8 ALTERNATE PLUGGING CRITERIA 90 DAY REPORT l

i l

August 1996

l l

TABLE OF CONTENTS Pane No.

1.0 Introduction 1-1 2.0 Summary and Conclusions 2-1 l

3.0 Sequoyah Unit-2 Pulled Tube Data 3-1 3.1 Sequoyah Unit-2 Pulled Tube Examination Results 3-1 3.2 Comparison of RPC Depth Profiles with Destructive Examination Results 3-6 3.3 Sequoyah Unit-2 Pulled Tube Evaluation for ARC Application 3-7 3.4 Comparison of Sequoyah-2 Data with Existing ARC Correlations 3-9 4

4.0 EOC-7 Inspection Results and Voltage Growth Rates 4-1 1

4.1 EOC-7 Inspection Results 4-1 l 4.2 Voltage Growth Rates 4-2 4.3 NDE Uncertainties 4-3 5.0 Data Base Applied for ARC Correlations 5-1 6.0 SLB Analysis Methods 6-1 7.0 Bobbin Voltage Distributions 7-1 7.1 Probability Of Detection (POD) 7-1 7.2 Calculation of Voltage Distributions 7-1 7.3 Predicted EOC-8 Voltage Distributions 7-2 8.0 SLB Leak Rate and Tube Burst Probability Analyses 8-1 8.1 Calculation of Leak Rate and Tube Burst Probability 8-1 8.2 Predicted Leak Rate and Tube Burst Probability 8-1 9.0 References 9-1 s:\spe\tva96\u2c8_90d.wp5 ii

f ,

SEQUOYAH UNIT - 2 CYCLE 8 ALTERNATE PLUGGING CRITERIA 90 DAY REPORT

1.0 INTRODUCTION

This report provides an evaluation of the Sequoyah Unit-2 steam generator (SG) eddy current data at tube support plates (TSPs) at End of Cycle 7 (EOC-7),

including Steam Line Break (SLB) leak rate and tube burst probability results, in support of the implementation of the Alternate Plugging Criteria (APC) for Cycle 8 operation as outlined in the NRC Generic Letter GL 95-05, Reference 9.1.

Calculations ofleak rates and probability of tube burst are reported for the EOC-7 condition based on measured bobbin voltage distributions. Also provided are projections of bobbin voltage distributions, leak rates and tube burst probabilities for Cycle 8 operation. The methodology used in these evaluations is in accordance with the plant-speci6c methodology for the Sequoyah Units 1 & 2 presented in Reference 9.2 as well as the generic methodology described in Reference 9.3.

The application of the TSP APC for the Sequoyah Unit-2 SGs involves a complete, 100% Eddy Current (EC) bobbin coil inspection of all TSP intersections in the tube bundles of all four SGs and plugging of TSP indications greater than 2 volts which are confirmed by a Rotating Pancake Coil (RPC) probe. RPC inspections are also performed at certain locations exhibiting dent voltages and mixed residual signals.

The measured bobbin signals are used to predict SG tube leak rate and probability of burst during a postulated SLB and show that they are within the allowable regulatory limits.

This report also summarizes results from laboratory examination of tube specimens pulled from Sequoyah Unit-2 SGs during the EOC-7 outage.

s:\apc\tva96\u2c8_90d.wp5 1-1 L

l I

l 2.0

SUMMARY

AND CONCLUSIONS SLB leak rate and tube burst probability analyses were performed for the actual ,

EOC-7 bobbin voltage distributions and projected voltage distributions for the  !

EOC-8 condition at Sequoyah Unit-2. SG 4 was found to be the limiting SG at EOC-7, and it is also projected to be the limiting SG for Cycle 8. The calculations demonstrate that APC application at EOC-7 (actual distribution) and EOC-8 satisfy NRC criteria for allowable leakage and burst probability.

A total of 366 axial outside diameter stress corrosion cracking (ODSCC) indications were found during the inspection in all four steam generators combined, of which '

only four indications had a voltage above one volt and none above two volts.

Steam generator 4 had the largest number ofindications found (170), and it is the limiting steam generator from the standpoint of SLB leak rate and tube burst probability. Twelve indications were inspected with a RPC probe and only two were confirmed. Two indications were located in tubes pulled to confirm ODSCC j and, accordingly,364 of the 366 indications were returned to service for Cycle 8. '

SG 4 with 170 indications had the largest number ofindications reported at EOC-7 ,

and all indications were returned to service for Cycle 8. SG 2 had the largest i indication reported at EOC-7,1.65 volts, and it was returned to service since it is below the 2 volt APC.

The bounding estimates for SLB leak rate and burst probability calculated using the measured EOC-7 voltage distributions are 0.07 gpm and 1.90x104 , respectively. l These values were calculated for SG 4 which is the limiting SG, and they are much  !

lower than the allowable SLB leakage limit of 3.7 gpm and the NRC reporting I guideline of 10-2 for the tube burst probability. j SLB leak rates and tube burst probabilities were also projected to EOC-8 l conditions for all four SGs using the Cycle 7 growth rate distribution based on reevaluated voltages from EOC-6 and EOC-7 inspection bobbin data. Projections were made using both the NRC required constant probability of detection (POD) )

value of 0.6 as well as a voltage-dependent POD termed probability of prior cycle l detection (POPCD). POPCD is established based on data from past IPC/APC i inspections, and it takes into account newly initiated indications which is important for APC application. The POPCD distribution used here is established  !

using data from 11 inspections conducted in 8 plants after 1992.  !

l SG 4 was also found to be the limiting SG for Cycle 8 operation. SLB tube leak rate for SG 4 is projected to be 0.35 gpm at the EOC-8 conditions and the burst probability is projected to be 1.90x10-5 These results, based on a conservative POD value of 0.6, are substantially lower than the Sequoyah Unit-2 APC allowable i s:\ ape \tva96\u2c8_90d.wp5 2-1 I

limit for SLB leakage (3.7 gpm) and the NRC guideline of 1.0x10 for the burst probability.

Two tube segments, each containing the first and second TSP crevices, were pulled during this outage per the generic letter requirement. One tube segment is from the hot side of tube R8C60 in SG-3. It had a bobbin voltage of 1.1 volts at the first TSP intersection which was confirmed by RPC as an axial indication; the  ;

second TSP intersection was also inspected with RPC and found to be NDD. The other tube segment is from the cold side of tube R4C23 in SG-2; it had a bobbin  !

voltage'of 0.4 volt at the second TSP intersection and RPC inspection of both intersections did not show any flaws. The 1.1 volt indication on R8C60, TSP 1 was ,

found to have a 60% maximum depth,34% average depth and 0.523 inch length with a burst pressure of 9,434 psi. The 0.4 volt indication on R4C23, TSP 2 was found to have only a 2% depth indication. The indication at R8C60, TSP 2 was found to have a 50% maximum depth,20% average depth and 0.602 inch length with a burst pressure of 10.269 psi. Reevaluation of the field data for this indication yielded 0.2 volt. The crack morphology for the indications is axial ODSCC with cellular patches typical of the EPRI database for APC application. l Incorporation of the Sequoyah Unit-2 data in the EPRI APC database would have l negligible influence on the APC correlations (SLB structural limit, using 95%/95% - I lower tolerance limit material properties, increases by 0.1 volt, i.e., from 8.7 volts to 8.8 volts).

Chemical cleaning of all four steam generators was performed at this outage. The .

tube segments removed from SGs 2 and 3 were examined to assess the effects of i chemical cleaning, if any, on surface deposits at the TSP intersections. The tubes i were found to be very clean in the free span between TSP intersections. DeFosits j remained on the tube within the TSP; although the deposits were not as thick as  ;

frequently found in other plants without chemical cleaning. There were no other j apparent effects of chemical cleaning relative to the application of the APC for i ODSCC at TSP intersections.

s:\apc\tva96Tu2c8.90d.wp5 2-2

3.0 SEQUOYAH UNIT-2 PULLED TUBE DATA  ;

3.1 Sequoyah Unit-2 Pulled Tube Examination Results 3.1.1 Introduction i 1

One cold leg tube (CL) segment (Tube R4C23) removed from SG 2 and one hot leg j (HL) tube segment (Tube R8C60) from SG 3 of Sequoyah Unit-2 were examined at l the Westinghouse Science and Technology Center primarily in support of alternative repair criteria (ARC) applications. The examination was conducted to characterize corrosion at the steam generator tube support plate (TSP) crevice locations. The tubes were selected to obtain a sampling of the indications observed in the spring 1996 field eddy current inspection to support Unit-2 application of the ARC for ODSCC at TSP intersections. The first and second TSP crevice regions (TSP 1 and TSP 2) of the tubes were removed. The TSP 1 region of HL Tube R8C60 and CL TSP 2 region of Tube R4C23 had original field eddy current calls of OD origin indications. The SGs were chemically cleaned prior to pulling the ,

tubes.  !

i 1

After nondestructive laboratory examination by eddy current, ultrasonic testmg, i radiography, dimensional characterization and visual examination, the TSP.1 i region of Tube R8C60, TSP 1 was leak tested at an elevated temperature.

Subsequently, room temperature burst testing was conducted on the leak tested TSP 1 region, as well as the non-leak tested TSP 2 of Tube R8C60, non-leak tested TSP 1 and TSP 2 regions of Tube R4C23, and a free span (FS) section from each of the two tubes (R8C60 and R4C23). The two burst tested TSP specimens of Tube R8C60 were destructively examined using SEM fractography techniques to characterize corrosion. In addition, all four TSP burst tested specimens were further examined using metallography.

I 3.1.2 NDE Results Visual inspection of the as-received tubes indicated no heavy deposits on the chemically cleaned tubes. The free span lengths of tubing were very clean while the TSP regions of tube R4C23 showed a very light deposit in some areas and the TSP regions of R8C60 showed relatively more and uniform deposit. However, there was no heavy deposit anywhere in the TSP or top of tubesheet regions of either tube.

Table 3-1 presents a summary ofimportant field and laboratory NDE results. The eddy current data were reviewed, including re-evaluation of the field data, to

- reassesc the voltages assigned to the indications and to assess the field no-s:\ ape \tva96\u2ca.90d.wp5 3-1

a .

detectable-degradation (NDD) calls for detectability under laboratory analysis conditions. Results of a third analysis, with particular emphasis on the field NDD l indications for incorporation into the ARC database, is discussed in Section 3.3.  !

In general, field and laboratory eddy current inspections (bobbin probe, RPC and l

+ Point probes) produced similar data for most of the regions examined.

For the TSP 2 of Tube R4C23, there was very little difference between the original field call and the field datc re-evaluation. The re-evaluation of the TSP 1 showed the presence of a distorted indication with some characteristics similar to that of the TSP 2. This signal does not meet the normal calling criteria for an indication.

The third analysis, discussed in Section 3.3, concludes that the TSP 1 indication is bobbin NDD. The 3-coil and + Point probes showed no indications for both the TSP regions. All indications were confined to the TSP crevice region. The laboratory, post-pull data of Tube R4C23 show little difference from the field data.

In the case of the TSP 1, there was an approximately two-fold difference in the signal strength (voltage) present but the indication remains NDD by RPC l inspection. 1 The re-evaluation of the field data for TSP 1 of Tube R8C60 resulted in only some minor differences in the RPC amplitudes measured. Allindications were confined to the TSP crevice region. The laboratory data of the tubes exhibited some differences from the pre-pull data. The dents in the' TSP 2 laboratory data are attributed to the tube pull process. In the case of the TSP 1, there was an approximately two-fold increase in the amplitude of the signal present in both the bobbin and RPC data. Also, there was a noticeable difference in the circumferential extent of the signals as measured by rotating probe techniques.

These differences are attributed to the pulling process and possibly suggest some tearing ofligaments between microcracks. The TSP 2 exhibited some suggestion of degradation in the post-pull data not present in the field data. Given the presence of a tube pull-related dent, it is suggested that some tearing ofligaments between microcracks occurred at this location which enhanced the detection of the degradation.

The laboratory eddy current data for the TSP 1 region of Tube R8C60 indications had a considerable width in the RPC and + Point data, and also in the laboratory UT data, suggesting the possibility of intergranular cellular corrosion (ICC) or three dimensional intergranular attack (IGA) in addition to and in association with axial cracking. Laboratory UT data suggested that both TSP regions of Tube R8C60 had indications. (Destructive examination also later found corrosion at the TSP crevice regions of this tube.)

Radiographic testing showed low level wall loss locally (pitting like indications) for the TSP 2 regions of Tubes R4C23 and R8C60, not confirmed during the s:\ ape \tva96\u2c8.90d.wp5 3-2

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

i subsequent destructive testing. The radiographic indications probably were related I to surface deposit variations.

l All the indications were found on the OD surface of the tubes. No corrosion indications were noticed on the ID surface during the NDE examination or subsequent destructive testing.

l 3.1.3 Leak, Burst and Tensile Testing )

l l The TSP 1 crevice region of tube R8C60, which had the largest original field eddy I current indications, was leak tested at elevated temperature and pressure at j conditions ranging from a simulated normal operating condition to a simulated l steam line break condition. For the normal operating conditions, the primary side pressure and temperature were nominally 1950 psi and 620*F and the secondary j side pressure and temperature were nominally 605 psi and 605'F. At the steam l line break conditions, the primary side pressure and temperature were nominally l 2780 psi and 618'F and the secondary side pressure and temperature were nominally 205 psi and 612*F. The tube did not develop any leak under these conditions.

1 i All four pulled TSP crevice region and two free span regions were burst tested at j room temperature at a pressurization rate of 2000 psi per second. The burst tests were performed simulating free span conditions with no TSP enveloping the indications. The TSP 1 crevice region of Tube R8C60, with relatively more degradation, was tested using a bladder and lubricated foil for the burst tests with  ;

! a " semi-constraint" condition which simulated the latere! constraint provided by the TSP located above the crack indication at prototypical spacing between TSPs.

I Results of the burst tests are presented in Table 3-2. All burst specimens developed axial burst openings. The openings for the TSP crevice region specimens of Tube R8C60 were within the crevice regions which had shown indications during laboratory NDE. The circumferential positions of the burst openings for this tube were close to the location of the deepest laboratory NDE indications. The bursts for R4C23 occurred above the TSP elevation indicating the likelihood of negligible degradation within the TSP All TSP specimens burst at high pressures. The lowest burst pressure for the TSP crevice regions (Tube R8C60, TSP 1, the 1.1 volt field bobbin indication) was 9434 psi,81% of the burst pressure ofits free span equivalent. Table 3-2 also presents room temperature tensile data obtained from FS sections of the pulled tubes. The tensile and burst strengths for ti:e free span

' sections are typical for Westinghouse tubing of this vintage.

l Following burst testing, a visual inspection showed the presence of cracking on both sides of the TSP burst openings of Tube R8C60. The corrosion was confined to the crevice regions. No cracking was visually identifiable on Tube R4C23 after the burst tests.

i s:\ ape \tva96\u2c8.,.90d.wp5 3-3

l 4

e 1

i 3.1.4 Destructive Examination Results l From post-burst test visual inspections, corrosion cracks were observed on the i burst faces of both TSP specimens of Tube R8C60. However, all four TSP specimens were destructively examined. All specimens selected for destructive examination were metallographically examined for corrosion. The specimens with corrosion cracks on the burst faces were also evaluated by SEM fractography. The tv o free span sections taken one frem each tube, selected for the reference burst pressure property test, had no degradation, as would be expected.

The burst fracture faces of the two TSP crevice region specimens from Tube R8C60 were opened for SEM fractographic examinations. Table 3-3 presents the results of the fractographic data in the form of macrocrack length versus depth, macrocrack length / average and maximum depth, and the number / location / width of ductile or uncorroded ligaments found on the TSP fracture faces. The TSP burst openings occurred in axial macrocracks that were composed of numerous axially I oriented intergranular microcracks of OD origin. Two ductile ligaments separating the microcracks were present on each burst opening macrocrack. All intergranular corrosion was confined within the crevice regions. For the TSP 1 region of Tube R8C60, the axial burst macrocrack had an average depth of 34% over a length of 0.523 inch with a mr.ximum depth of 60% while the burst macrocrack of the TSP 2 region had an average depth of 21% over a length of 0.602 inch with a maximum l depth of 50%.

Figures 3-1 to 3-4 present sketches of the TSP region burst openings. Figures 3-3 and 3-4 also show crack distributions on the OD surface of the tube found by visual (30X stereoscope) examinations. The sketches show the locations where cracks were found and their overall appearance, not the exact number of cracks or their detailed morphology. All corrosion was confined to the crevice regions.

Transverse metallographic sections were taken at the maximum width of the burst openings. These sections were in the mid TSP regions of Tube R8C60 and ' above the TSP regions of Tube R4C23. Additional transverse samples were taken in the  ;

mid TSP regions of Tube R4C23 to examine for corrosion cracking within the TSP elevation. Due to the complexities of the crack networks observed in the TSP regions ofTube R8C60, radial metallography was utilized, in addition to transverse metallography, to provide an overall understanding of the intergranular corrosion ,

morphology. In radial metallography, small sections of the tube (typically 0.5 by l 0.5 inch) are flattened, mounted with the OD surface facing upwards and then j progressively ground, polished, etched, and viewed from the OD surface towards l the ID surface. Table 3-4 provides a summary of the metallographic data. g From the metallographic examinations conducted on the TSP 1 region of Tube R8C60, it was concluded that the dominant OD origin corrosion morphology was s:\ ape \tva96\u2c8.90d.wp5 3-4 j l

axialintergranular stress corrosion cracking (IGSCC). In addition, there was some intergranular cellular corrosion (ICC) found in association with the axial IGSCC.

With an ICC morphology, a complex mixture of short axial and oblique angled cracks interact to form cell-like structures. Figure 3-5 provides an example of the corrosion morphology found at the TSP 1 of Tube R8C60 by radial metallography at a depth 2% below the OD surface. With progressive radial grinding, it was shown that the axial IGSCC became more dominant with depth while the ICC tended to disappear. Figure 3-6 provides the corrosion morphology at the TSP 2 region of Tube R8C60 at a depth 2% below the OD surface. This figure shows also the presence ofICC along with IGSCC. However, in the TSP 2 region, ICC was '

not as deep as in the TSP 1 region as shown in Table 3-4.

IGSCC morphology can be characterized by depth-to-width (D/W) ratios of the cracks. The widths are measured at mid-depths. IGA involvement has been characterized by three arbitrary categories of(D/W) ratios. D/W ratios greater than 20 are defined as having minor involvement, ratios between 3 and 20 as moderate, and ratios less than 3 as having significant IGA involvement. Crack density is also considered an important parameter in characterizing corrosion.

l Crack densities greater than 100 cracks in 360 degrees are defined as high while '

values less than 25 are defined as low. The OD origin axial intergranular corrosion observed by metallography in the TSP crevice regions of Tube R8C60 i had similar crack densities and crack morphologies. The crack density was medium and the crack morphology was moderate, as measured by D/W ratios. The l D/W ratio was 10 for the TSP 1 region and 6 for the TSP 2 region. The ratio for l the TSP 2 region is less because the cracks were not as deep in as they were in the TSP 1 region even though the width ofIGA involvement was the same. Table 3-4 l presents a summary of the metallographic data. The TSP 1 and TSP 2 specimens of Tube R8C60 specimen had an estimated 45 and 40 cracks respectively over the tube circumference in the crevice region with the cracking concentrated near the burst fracture.

The TSP regions of Tube R4C23 did not show any corrosion cracks on the burst openings, the OD surface of the tube (Figures 3-1 and 3-2), or on the transverse metallographic sections taken at the center of burst section or in the TSP crevice l region. (Table 3-4). Only minor isolated surface corrosion, s 2% deep, was neticed l at the tube OD,in the TSP crevice region.

l

( 3.1.5 Conclusions Both the TSP crevice regions of Tube R8C60, hot leg from SG 3, had OD origin corrosion present. Metallographic data showed that the corroded TSP crevice 1 l regions had combinations of axially oriented IGSCC and ICC with the axial IGSCC l predominating. The depth ofIGSCC and ICC was greater for the TSP 1 region as s:\apc\tva96\u2c8.90d.wp5 3-5

compared to the TSP 2 region. All TSP region corrosion was confined to the crevice regions. The corrosion morphology was typical of pulled tubes within the EPRI database. The TSP crevice regions of Tube R4C23, cold leg from SG 2, did not show any corrosion cracking during burst or metallographic testing. Only minor isolated surface corrosion, s 2% deep, was noticed at the tube OD, in the TSP-2 crevice region of R4C23.

Eddy current bobbin and other (RPC, + Point, Cecco) probe data correlated well with the corrosion distribution for the cracks of Tube R8C60. Of the NDE techniques, laboratory UT provided the most accurate description of the TSP region corrosion, both in numbers of the TSP regions with corrosion (2 out of 2) and in the area extent and orientation of the corrosion.

The TSP crevice region burst pressures ranged from 9,434 to 12,378 psi. All burst pressures were well above safety guidelines of R.G.1.121 and close to free span burst values, (i.e., those without corrosion) except for the TSP 1 region of Tube R8C60 which burst at 81% of its free span equivalent pressure. The burst pressure data were consistent with expectations and near the mean predictions for the alternative repair criteria burst pressure versus bobbin voltage correlation.

} 3.2 Comparison of RPC Depth Profiles with Destructive Examination Results Although not a part of the ARC for ODSCC at TSP intersections, industry efforts are being applied to develop software and procedurer for obtaining length versus depth profiles from RPC and + Point data. Depth profiling for R8C60, TSP 1 was performed prior to the destructive examination of the indication. The other, very low voltage indications were too small for depth sizing. The predicted depth profile is compared with the destructive examination results in this section.

Figure 3-7 shows the comparison of the + Point coil, eddy current depth profile with the destructive exam data for R8C60, TSP 1. The destructive exam length of 0.523" is somewhat longer than the NDE length of 0.38". The destructive exam results show a shallow tail ofless than about 20% depth which was not detected by the + Point coil and depths for the lower end of the crack are underestimated.

The average depth of 48.7% from NDE is larger than the 33.6% by destructive exam. Overall, the NDE results are conservative for calculating the burst pressure of the indication since the shallow tails of the crack do not contribute to the burst  !

pressure. The burst pressure calculated from the destructive exam profile is 9,467 psi (effective or weak link crack length is 0.44" with an average depth of 39%)

compared to the measured 9,434 psi. The burst pressure calculated from the NDE profile is 9,133 psi (weak link crack length is 0.35" with an average depth of 52%).

s:\apc\tva96\u2c8.90d.wp5 3-6

l ,

. . i i

l l

3.3 Sequoyah Unit-2 Pulled Tube Evaluation for ARC Applications The pulled tube examination results were evaluated for application to the EPRI .

database for ARC applications. The eddy current data were reviewed, including I reevaluation of the field data, to finalize the voltages assigned to the indications and to assess the field NDD calls for detectability under laboratory conditions. The data for incorporation into the EPRI database 'were then defined and reviewed against the EPRI outlier criteria to provide acceptability for the database. l 3.3.1 Eddy Current Data Review

Table 3-5 provides a summary of the eddy current data evaluations for the  ;

i Sequoyah Unit-2 pulled tubes. These NDE data results have been discussed in the l above Section 3.1.2. As noted above, the field and laboratory reevaluations of the field bobbin data are in good agreement for the field call at R8C60, TSP 1 and I R4C23, TSP 2. An additional laboratory reevaluation of the field data was performed, particularly to assess the NDD calls for R8C60, TSP 2 and R4C23, TSP l 1. Figures 3-8 to 3-11 show the bobbin analysis results for this reanalysis. The reevaluated field bobbin voltages, including the adjustment for cross calibration of the field ASME standard to the laboratory standard, are used for the EPRI ARC l database. The reevaluation was performed by the same analyst that pcrformed a )

large part of the EPRI pulled tube database and the use' of these voltages '

minimizes analyst variability in the database, which is separately accounted for l in ARC applications as an NDE uncertainty.

I

! The TSP 2 indication of R8C60 and the TSP 1 indication of R4C23 were found to  !

be bobbin NDD in the field data. These indications are associated with maximum I crack depths of 50% and no degradation, respectively, with an average depth of 20% for R8C60, TSP 2. The R8C60, TSP 2 indication was identified by reanalysis of the field data to be a 0.2 volt bobbin indication confirmed by + Point. The post-pull laboratory inspection identified the indication by all RPC, Cecco and UT probes although the bobbin data is masked by a dent from the tube pulling operations. The R4C23, TSP 1 indication is NDD by all pre and post pull analyses except one analyst evaluating the field and laboratory bobbin data. The bobbin analysis is shown in Figure 3-10 and shows no significant flaw response in the single frequency results and is typical of non-flawed mixed residuals found in field inspections. The bobbin response for TSP 2 of R4C23, which had only a 2%

corrosion depth, has a more significant flaw like response at all frequencies even though the corrosion depth is expected to be too small to cause the flaw like bobbin response at TSP 2. For ARC applications, it is appropriate to consider TSP 1 to be NDD and TSP 2 to be a flaw indication.

1 The Sequoyah Unit-2 SGs were chemically cleaned prior to the tube pull at EOC-7. I Visual examination for tube surface deposits indicates that the tubes were i

l s:\ ape \tva96\u2c8.90d.wp5 3-7

essentially free of deposits over the free span regions of the tubes between TSPs'.

The tube sections within the TSP crevices had OD deposits following the chemical cleaning and the tube pull operations. The area of the tubes near the top of the TSP were essentially free of deposits. Therefore, no definitive statement about deposit removal at the TSPs can be made except it is clear that the chemical cleaning did not remove all deposits within the TSP crevices and the cleaning operations for the crevices were not as effective as for the free span sections of the tubing. There is na reason to believe that bobbin voltages were significantly affected by the cleaning operations since the changes in post-pull voltages are similar to that found for tubes without chemical cleaning.

3.3.2 Sequoyah Unit-2 Data for ARC Applications The pulled tube leak test, burst test and destructive examination results are summarized in Table 3-6. The R8C60, TSP 1 indication did not leak at SLB '

conditions. No leakage for the other indications is inferred from the shallow corrosion depths. Since the TSP 1 indication of R4C23 is field bobbin NDD, this indication cannot be used in the EPRI ARC database for the voltage correlations.

The Sequoyah Unit-2 pulled tube results were evaluated against the EPRI data exclusion criteria for potential exclusions from the database. . Criteria la,to^1e apply primarily to unacceptable voltage, burst or leak rate measurements and indications without leak test measurements. Criteria Ic to le are not applicable to the Sequoyah Unit-2 indications. .The indication at R4C23, TSP 2 requires evaluation against criteria la and Ib. Criterion la applies to indications with corrupted bobbin voltage measurements which includes extraneous (not ODSCC) factors influencing the voltage measurements. Criterion 1b applies to an inappropriate burst test. The 0.35 volt TSP 2 response for'R4C23 is apparently a false signal for the associated 2% depth since the 2% depth would not be detectable by bobbin inspection. The bobbin voltage would be associated with deposits, TSP effects or other contribution to a mixed residual signal and exclusion Criterion la is applicable to this indication. This is consistent with the indication not being detectable by any other probe (+ Point, UT, etc.). In addition, the indication burst in the free span outside the TSP and is thus not associated with the bobbin voltage measurement. Although the burst test was appropriately performed and, burst outside the TSP is reasonably expected for the destructive exam results, data exclusion Criterion Ib is applicable to the burst data since the burst pressure is not associated with the flaw at the TSP. Therefore, the R4C23, TSP 2 indication is excluded from all ARC correlations per Criteria la and Ib.

Criterion 3 applies to potential errors in the leakage measurements and is not applicable to the Sequoyah Unit-2 indications with no leakage.

s:\apc\tva96\u2c8.90d.wp5 3-8 t .

^

EPRI Criterion 2a applies to atypical ligament morphology for indications having high burst pressures relative to the burst / voltage correlation and states that high

. burst pressure indications with s; 2 uncorroded ligaments in shallow cracks < 60%

deep shall be excluded from the database. Table 3-6 identifies the number of

)'

remaining ligaments and the maximum depths for the indications. The R8C60, TSP 1 indication has two ligaments with a maximum depth of 60%. However, the j indication lies almost on the mean burst correlation and does not satisfy the exclusion criterion. The R8C60, TSP 2 indication has two ligaments with a j maximum depth of 50%. ' However, the indication lies just below the mean burst correlation and does not qualify for exclusion from the database. I i

As shown in the last column of Table 3-6, the TSPs 1 and 2 indications of R8C60 are to be included in the probability of leakage and burst correlations. The indication at R4C23, TSP 2 is excluded from the database per EPRI exclusion

! Criteria la and ib. The impact of the indications on the ARC correlations is j further discussed in Section 3.4.

i s

3.4 Comparison of Sequoyah Unit 2 Data with Existing APC Correlations j This section reports on the evaluations performed which utilized the results ofleak l rate and burst testing of tube sections which were removed from Sequoyah Unit-2

, in 1996. The results of the destructive examination of the tube sections is recorded

in Section 3.1 of this report. The Sequoyah 2 pulled tube data germane to the APC i correlations, and the bobbin amplitudes for APC applications, are given in Table

! 3-6. The results of the destructive examinations, e.g., leak and burst tests, are l compared to the database2 of similar test results for 7/8" outside diameter steam

' generator tubes. In addition, the effect of including the new test data in the

, reference database was evaluated. In summary, the test data are consistent with i the database relative to the burst pressures and the probability of leas as a function of the bobbin amplitude. (No comparison ofleak rates is possible since the specimens did not leak at the SLB pressure.) These comparisons and evaluations ,

i are discussed below.

i i j 3.4.1 Suitability for Inclusion in the Database l .

The report information on the destructive examinations of the tube sections was l

reviewed relative to the EPRI guidelines for inclusion / exclusion of tube specimen i data in the alternate plugging criteria (APC) database, as discussed in Section 3.3. ,

i 2

i The database consisted of the EPRI recommended database as documented in the addendum to EPRI report NP-7480-L.

i a:\ ape \tva96\u2c8.90d.wp5 3-9 i

This review revealed no information that would lead to a conclusion that the data should not be included in the database. Therefore, the resulting correlations -

should be considered applicable to the use of APC to indications in 7/8" diameter tubes in Westinghouse SGs.

3.4.2 Burst Pressure vs. Bobbin Amplitude Results from two (2) burst tests, performed on tube specimens which exhibited non-zero bobbin amplitudes at TSP elevation locations, were considered for evaluation.

A plot of the burst pressures of the Sequoyah Unit-2 specimens is depicted on Figures 3-13 and 3-14 relative to the burst pressure correlation developed using the latest recommended reference database.'

1. A visual examination of the data relative to the EPRI database indicated that the burst pressures measured fall well within the scatter band of the reference data. This evident from the positions of the data within the tolerance band of Figure 3-13 and from the nearness of the data points to the reference regression line illustrated on Figure 3-14.

2. Both data points fall within a 90% non-simultaneous two-sided prediction band about the regression line (the one-sided 95% prediction curve depicted is the lower bound of the two-sided 90% prediction band). Since a two-sided simultaneous prediction band for the two data points would be wider than the non-simultaneous band, no statistically significant anomalies are indicated.

I In summary, the visual examination doesn't indicate any significant departures from the reference database.

Since the Sequoyah Unit-2 burst pressure data were not indicated to be from a separate population from the reference data, the regression analysis of the burst pressure on the common logarithm of the bobbin amplitude was repeated with the additional data included. A comparison of the regression results obtained by including these data in the regression analysis is provided in Table 3-7. Regres-sion predictions obtained by including these data in the regression analysis are also shown on Figure 3-14. A summary of the changes is as follows:

1. The intercept of the burst pressure, P3, as a linear function of the common logarithm of the bobbin amplitude regression line is decreased by 0.09%.

8 The database is not shown since it is proprietary to the Electric Power Research Institute.

s:\ ape \tva96\u2c8_90d.wp5 3-10

This has the effect of decreasing, albeit not significantly, the predicted burst pressure as a function of the bobbin amplitude.

2. The slope of the regression line is decreased by 0.05%, i.e., the slope is less steep. This has the effect ofincreasing the burst pressure as a function of bobbin amplitude for large indications.

3. There is a decrease in the standard error of the residuals of 0.8%. The effect of this change would be reflected in a slightly smaller deviation of the 95%

prediction line from the regression line.

The net effect of the changes on the SLB structural limit, using 95%/95% lower tolerance limit material properties, is to increase it by 0.1 volt, i.e., from 8.7 volts to 8.8 volts. The decrease in the slope and standard error coupled with the fact that the structural limit is also increased indicates that the probability of burst would also decrease for bobbin indications over the structural range ofinterest.

Based on the small change in the structural limit, the change in the probability of burst would be expected to be not significant.

3.4.2 Probability of Leak .

~

The data of Table 3-6 were examined relative to the reference correlation'for th'e' pol as a function of the common logarithm of the bobbin amplitude.' Figure'3 illustrates the Sequoyah Unit-2 data relative to the reference correlation. All of

the specimens exhibited pol behavior commensurate with expectations indicated

by the reference regression curve. Based on the visual examination, there is no significant evidence ofirregular results, i.e., outlying behavior is not indicated.

In order to assess the effect of the new data on the correlation curve, the database was expanded to include the Sequoyah Unit-2 data and a Generalized Linear Model regression of the pol on the common logarithm of the bobbin amplitude was repeated. A comparison of the correlation parameters with those for the reference .

database is shown in Table 3-8. These results indicate:

1. A 0.2% reduction (larger negative value) in the logistic intercept parameter.

2. A 0.2% increase in the logistic slope parameter.

3. The absolute values of the parameters' covariance matrix changed by 0.3%

to 0.4%.

4. The Pearson standard error decreased by 0.1% from 0.571 to 0.566. This is a negarive indicator since the ideal value would be 1.0, but is not judged to be significant.

s:\ ape \tva96\u2c8.90d.wp6 3-11 m

J In order to assess whether or not these changes are significant, the reference correlation and the new correlation were also plotted on Figure 3-14. An examina-tion of Figure 3-14 reveals essentially no change, in an absolute sense, in the correlation over the entire range of the data. It is noted that when the total leak rate is determined using the leak rate to bobbin volts correlation, the resulting value can be quite insensitive to the form of the pol' function. Hence, the effect l of the changes in the parameter values and variances is judged to be insignificant relative to the calculation of the expected total leak rate.

3.4.3 Leak Rate vs. Bobbin Amplitude As previously noted, none of the specimens exhibited leakage at the SLB differ-ential pressure. Since the reference correlation ofleak rate to voltage exhibits a j p-value of 1.4% for the slope parameter, the use of the correlation in performing Monte Carlo simulations to estimate the total leak rate is considered to be l

justified, based on the requirements stipulated in the NRC Generic Letter for voltage based plugging criteria. )

3.4.4 General Conclusions -

The review of the effect of the Sequoyah Unit-2 data indicates that the burst J pressure and the probability ofleak correlations to the common logarithm of the i bobbin amplitude would not be significantly changed by the inclusion of the data. l Therefore, it is likely that the conclusions relative to EOC probability of burst and l

EOC total leak rate based on correlations obtained using the reference database j would not be significantly affected by repeating those analyses using an expanded I database which includes the Sequoyah Unit-2 test data.

I l

l l

l i

I i

l l

l l l s:\apc\tva96\u2c8.90d.wp5 3-12

Table 3-1 Comparison of NDE Indications Observed at Sequoyah Unit-2 on Pulled S/G Tubes Location Field E/C Lab E/C Lab UT Data Lab X-Ray R4C23, Bobbin: NDD (0.29 V DI - Bobbin: 0.64 V DI - non- NDD NDD TSP 1, non-quantifiable)* quantifiable SG 2, CL REC: NDD REC: NDD

+ Point: NDD Cecco: NDD

+ Point: NDD R4C23, Bobbin: 0.41 V, 27% deep, Bobbin: 0.45 V,35% deep, NDD Low level wall loss TSP 2, OD PI DI locally (pitting like 5'12, CL (0.35 V,27% deep, OD DI REC: NDD indications) due to tube noise)* Cecco: NDD REC: NDD + Point: NDD

+ Point: NDD

()* = Eddy current reevaluation value using cross calibration of ASME standard to reference lab standard.

Legend of Abbreviations:

Ind = Indication TSP = tube support SAI = single axial ind. NDD = no detectable degradation RPC = Rotating Pancake Coil plate MAI = multiple axial ind. TTS = top of tubesheet MCI = multiple cire. ind. V = volts DI = distorted indication PI = possible indication s:\apc\tva96\u2c8_90d.wp5 3-13 .

Table 3-1 (Continued)

Comparison of NDE Indications Observed at Sequoyah Unit-2 on Pulled S/G Tubes Location Field E/C Lab E/C Lab UT Data Lab X-Ray R8C60, Bobbin: 1.1 V, PI ( 1.1 V, PI - Bobbin: 1.93 V,21% deep, DI Network ofindications in NDD.

TSP 1, 94% deep)* EEC: MAI,1.78 V, 38% deep, axial and circumferential SG 3, HL REC: SAI, 0.96 V, 0.34" long, 48* 0.55" long at 235' with a directions on the OD of circumferential extent (SAI, circumferential extent of 135* located between 188 and 0.60 V,58% deep,0.39" long,45' Cecco: PI with a circumferential 317' with a depth of 20 to of cire. extent)* extent of 120*, 68% max. depth 30%. Also shallow

+ Point: SAI, 0.31 V, 0.28" long, + Point: MAI, (distorted),0.22 V, indications (less than 20%

50* of circumferential extent 75% deep,0.53" long at 224'with deep) located between 9 (SAI, 0.20 V,79% deep,0.28" a circumferential extent of 129* and 21* and at 38*.

long, 50* of circ. extent)*

R8C60, Bobbin: NDD Bobbin: 4.24 V dent in TSP 2 and Network of shallow Low level wall TSP 2, BEC: NDD 0.79 V dent at 2.60" below TSP 2 indications (less than 20% loss locally SG 3, HL + Point: NDD deep) in axial and (pitting like REC: Lift off signals, possible circumferential directions indications)

SAI,0.23 V,0.30 long,41* of on the OD located between circumferential extent, non- 110 and 171* and 236 and quantifiable depth 300*.

Cecco: PI with a circumferential extent of 45*, dent with distorted indication (estimated depth <

20%)

+ Point: SAI, (distorted),0.19 V,

< 20% deep, 0.36" long at 303*

with 56" of circumferential extent s:\npe\tva96\u2c8_90d.wp5 3-14 .

Table 3-2 Room Temperature Burst and Tensile Test Data for Sequoyah Unit-2 S/G Tubes Location Burst Burst Burst Burst 0.2% Offset Tensile Tensile Pressure, Ductility, Length, Width, Tensile Yield Ultimate Elongation, psig  % inches inches Strength, psi Strength, psi  %

R4C23, FS, SG 2, CL 12422 32.6 2.008 0.383 56,779 107,416 37.1 R4C23, TSP 1, SG 2, CL 12378 31.8 1.988 0.375 R4C23, TSP 2, SG 2, CL 12305 32.2 1.933 0.383 R8C60, FS, SG 3, HL 11616 24.2 2.285 0.310 55,730 107,865 38.3 _

R8C60, TSP 1, SG 3, HL 9434 14.1 1.264 0.331 R8C60, TSP 2, SG 3, HL 10269 15.3 1.382 0.310 Control, NX8161 11587 52,308 102,615 35.7 Legend:

TSP = tube support plate; FS = free span, TTS = top of tubesheet; SG = steam generator

• = Burst with foil and bladder in a semi-restraint condition, all others burst without restraint, bladder, or foil.

+ = Failed outside gage length, reducing the measured ductility.

s:\ ape \tva96\u2c8_90d.wp5 3-15 .

3 Table 3-3 Sequoyah Unit-2 SG Tube Intergranular Macrocrack Profiles for OD Origin Corrosion Tube, Length vs. Depth & Ductile Ligament Data Positional Information Comments Specimen (inches /% throughwall)

R8C63, TSP 1, 0.00/00 Crack Top (located 0.10" below The axially oriented SG 3, HL 0.02/05 TSP top) burst macrocrack '

(Axial Burst 0.04/03 had two ductile Crack) 0.06/05 ligaments with  !

0.08/08 dimple rupture 0.10/25 features occurring 0.12/10 over more than 50%

0.14/08 of their lengths.

0.16/20 0.18/53 0.20/45 0.22/50 0.24/50 0.26/50<-ugament u o.008" wide 0.28/50 0.30/50 0.32/50 0.34/58 (0.36/60)<-(Max. depth = 60%)

0.38/50 0.40/51<-ugament 2/ o.005' wide 0.42/45 0.44/43 0.46/40 0.48/55 0.50/40 0.52/08 0.523/00 Crack Bottom (located 0.623" Ave. depth = 34% Macrocrack Length = 0.523 inch below TSP top) s:\ ape \tva96\u2c8_90d.wp5 3-16 .

F Table 3-3 (Continued) -

Sequoyah Unit-2 SG Tube Intergranular Macrocrack Profiles for OD Origin Corrosion Tube, Length vs. Depth & Ductile Ligament Data Positional Information Comments Specimen (inches /% throughwall)

R8C60, TSP 2, 0.00/00 Crack Top (located 0.125" below The axially oriented SG 3, HL 0.02/06 TSP top) burst macrocrack (Axial Burst 0.04/16 had two ductile ,

Crack) 0.06/16 ligaments with 0.08/12 dimple rupture 0.10/06 features occurring 0.12/25 over more than 50%

0.14/22 of their lengths.

0.16/35 0.18/31 0.20/31 0.22/28<-Ligament u o.010" wide 0.24/25 0.26/38 0.28/31 0.30/25 0.32/38 0.34/41<___ Ligament 2/ 0 006 wide 0.36/35 0.38/35 (0.40/50) <-(Max. depth = 50%) ,

0.42/28 0.44/28 0.46/19 0.48/12 0.50/06 0.52/05 0.54/06 0.56/06 0.58/03 0.602/00 Crack Bottom 00cated 0.727" Ave. depth = 21%, Macrocrack Length = 0.602 inch below TSP top) s:\ ape \tva96\u2c8_90d.wp5 3-17

Table 3-4 Metallographic Data of Sequoyah Unit-2 Steam Generator Tubes Est'imated Max. Depth of ICC Avg.D/W Section Cracks Maximum Max 1 Avg. Depth Oblique and Axial Ratio from Number Components (% Transverse of Length per Number of (% Throughwall)

Specimen Section Type Cracks at Mid- Throughwall in Radial Section Cracks Unch) Inch crevice Location Section)

R4C23, Transverse - Burst 0 2.75 0 0 NA NA NA TSP 1 Opening SG 2, CL (1.1" above TSP top)

Transverse - (Mid TSP) 0 2.75 0 0 NA NA NA R4C23, Transverse - Burst 0 2.75 0 0 NA NA NA TSP 2, Opening (0.5" above TSP SG 2, CL top)

Transverse - (Mid TSP) 0 2.75 0 0 NA NA NA RSC60, Transverse - (Mid TSP) 23 2.02 11 45 51/21 10 TSP 1, SG 3,IIL Radial 18 0.36 50 depth = 2% 24%< Oblique <50%

Radial 14 0.39 36 depth = 10% Arial>50%

Radial 15 0.41 36 depth = 24%

Radial 4 0.41 11 depth = 50%

R8C60, Transverse -(Mid TSP) 17 2.06 8 40 20/8 6 TSP 2, SG 3,IIL Radial 18 0.38 47 depth = 2% 2%< Oblique <10%

Radial 12 0.39 31 depth =10% Axial >34%

Radial 11 0.41 27 depth = 24%

Radial 2 0.41 5 depth = 34%

• Minor isolated surface corrosion, s 2% deep, was noticed in some areas on the tube OD.

a:\apc\tva96\u2c8_90d.wps 3-18 .

Table 3-5. Summary of Plant W-21996 Pulled Tube Eddy Current Results 1 Field Call Lab. Reevaluation of Field Data Post Pull Data Tube T S Bobbin + Pt. Bobbin ASME Bobbin Depth + Pt. Bobbin RPC +

P Volts"' Volts Volts Cal. Volts'85 Volts Volts 3-Coil Point Cecco UT R8C60 1 1.10 0.31 y 1.01 1.081 1.09(1.10) 85 % 0.24 y 1.93 1.78 v 0.22 v PI MAI ,

Hot Leg SAI MAI MAI MAI 2 NDD NDD 0.19 1.081 0.20(NDD) DI 0.18 v Dented 0.23 v 0.19 v PI MAI SAI R4C23 1 NDD NDD NDD -

NDD(0.29) -

NDD 0.64 NDD NDD NDD NDD Cold  ;

Leg 2 0.41 NDD 0.42 0.842 0.35(0.35) DI NDD 0.45 v NDD NDD NDD NDD Notes: 1. Field data include cross calibration of ASME standard to the reference laboratory standard.

2. ASME calibration represents the cross calibration factor for the field ASME standard to the reference laboratory standard and is applied to the laboratory reevaluation to obtain the corrected APC volts. Two laboratory reanalyses of the field data are given in the Table. The first value given (without parentheses) is used for ARC evaluation::- See text for discussion of the differences. .

r

. t s:\ ape \tva96\u2c8_90d.wp5 3-19

[

Table 3-6. Plant W-21996 Pulled Tube Data for ARC Applications T Bobbin Data Destructive Examination Leak Rate- Burst Pressure Data - kai Use in Tube S RPC Results 1/hr Corr.

p' Volts Note 5 Max. Avg. Crack No. N. O. SLB Meas. o, o, Adj."

Volts Depth Depth Depth Length Lig." 1300 2560 Burst Burst paid psid Press. Press.

1 R8C60 1 1.09 85 % 0.24 60% 34 % 0.523" 2 0.0 0.0 9.434 7.932 B, POL Hot 2 0.20 DI 0.18 50%'8' 21% 0.602" 2 0.0'8' O.0'" 10.269 8.634 B, POL Leg FS 11.616 55.7 107.9 9.767 R4C23 1 NDD -

NDD 0% - - - 0.0'8' O.0'8' 12.378 10.370 None Cold Outside Leg TSP 2 0.35 DI NDD 2% - - -

0.0'8' O.0'8' 12.305 10.309 None Outside TSP FS 12.422 56.8 107.4 10.407 Notes:

1. FS is freespan section of tubing with no tube degradation to obtain tensile properties and undegraded tubing burst pressure.

2. Number of uncorroded ligaments with > 50% ofligament length remaining in burst crack face.

3. Inferred from destructive exam. depth, leak test not performed. Corrosion depth too shallow for leakage at SLB conditions. '

4. Burst pressures adjusted to 68.78 ksi, average flow stress at 650' F for 7/8 diameter tubes (Reference 3.6).

5. B = data to be used in burst correlation, POL = data to be used in probability ofleakage correlation, L = data to be used in lealc rate correlation.

6. Crack is > 30% deep only over about 0.1". _

t s:\ ape \tva96\u2c8_90d.wp5 3-20

= ,

I l

i i

i i

Table 3.7: Effects of the Sequoyah Unit 2 Data on the Burst Pressure vs. Bobbin Volts Correlation

• i P, = a + a log 1 2 (Volts)

Parameter Reference Database Database with Value

• Sequoyah-2

% 7.6003 7.5938

% -2.3645 -2.3528 or,,,, 0.8285 0.8222 N (data pairs) 79 81-p Value for % 2.5 10 8 3.4 10'8 8

r 81.9% 82.0%

Notes: (1) The reference flow stress for the determination of the parameters of the correlation equation ,

was 68.78 ksi. '

(2) The reference database is as documented in the addendum to EPRI NP-7480-L.

s:\ ape \tva96\u2c8.90d.wp5 3-21

l l

l l

i 1

i Table 3.8: Effect of Sequoyah Unit 2 Data on the Probability of Leak Correlation Pr(Leak) = {1 + e -l' * '21sm]}-1 Parameter Reference Database Database with Value

• Sequoyah 3 -5.5778 -5.5875

-2 7.4334 7.4446 V11

• 2.0432 2.0353 V12 -2.3713 -2.3623 V22 3.2038 3.1941 DoF* 94 98 Deviance 24.61 24.62 Pearson cem, 0.571 0.566 Notes: (1) The reference database is as documented in the  ;

addendum to EPRI NP-7480-L. l (2) Parameters V are u elements of the covariance matrix of the coefficients, pi, of the above regression equation.

, (3) Degrees of Freedom I

s:\ ape \tva96\u2c8_90d.wp5 3-22

f L

' I I ,

2.25 - ,

2.00 - l D

fl .

9 c

o 1.00 -

n -

. \

5 ill l i

i 0.00 I I SP Top 0* 90* 180* 270* 360*

Circumferential Position (degrees)

Figure 3-1 Sketch of the OD surface showing the burst fracture opening at the top of the first tube support plate (TSP 1) of Tube R4C23. No cracking was noticed on the fracture face and OD surface of the tube.

3-23 .

__ _ _ _ _ _ . . _ _ _ _ _ _ . _ . _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ . _ _ . _ _ _ _ _ ___ ________m_____.m _ _ _ _ _ _ _ _ _ _ . _ . _ _ __ _ _ _ _ . - _ _ _ _ _ _ _ _ _

1 I I 2.25 -

2.00 -

E f

.s

~

l

@ 1.00 - -

Ca '

g - SP Top i

0.00 i i i 0* 90* 180* 270* 360* .

Circumferential Position (degrees) l Figure 3-2 Sketch of the OD surface showing the burst fracture opening 'at the second tube support plate  !

(TSP 2) of Tube R4C23. The burst opening extended above the top of TSP crevice region. No cracking was noticed on the fracture face and OD surface of the tube.

.:t.peuva96\u2cy8pd wp5 3-24 ,

I I I 1.25 -

SP Top E '

1-@ - /

s  %

) Il c

a

. {7 ' >\\

h d

la 0.50 - kh sLg; I

I N - SP Bottom 0.00 i i i 0* 90* 180* 270* 360*

Circumferential Position (degrees)

Figure 3-3 Sketch of the OD crack distribution found at the first support plate (TSP 1) of Tube R8C60. Also shown is the location of the burst fracture opening. The burst opening extended beyond the TSP crevice region, but the corrosion cracking was confined to the crevice region.

s:\ ape \tva96\u2cy8_90d.wp5 3-25

1 I I 1.50 -

3

- SP Top 1.00 ~ ,' f, ,h ,I 'j 8 /

aN .

hl

\il I

/j E

t 0.50 - '

5((

\ 'g - SP Bottom 0.00 i i i 0* 90* 180* 270* 360*

Circumferential Position (degrees)

Figure 3-4 Sketch of the OD crack distribution found at the first support plate (TSP 2) of Tube R8C60. Also shown is the location of the burst fracture opening. The burst opening extended beyond the TSP crevice region, but the corrosion cracking was confined to the crevice region.

s:\apc\tva96\u2cy8_90d.wp5 3-26

?

5 .

l i

1 -

i

. p,f '-5>y h.g r . .

',1, . 9 j . .

?:

=

. u c.A r.l .:: i . :.

,,4.

#' A vfi-

. . [-;.M., ....- -', y, .-

{t a

s 'h, ..m. ,Q - O

Tr. b

1. ~ 'N- ( CL 1,y w

_ . p. .

,; c p .

m x ~ g.: :

w:

s

, .y .

w. =.:.

s: ,xw- .

__ =

1

?

SC-

s;;y 2 . . .

. Om

r. ;.

, c; j y~- u,

.s.

. ::n. c. .;.

m .. .

..g t ,,.. .j s.o l .p  ;. % .

-,.w.

a ..

n I w. .. a ,59 w, t 1.rv p.< 3 *, 6.. . N .

..;;. ~... 5y E;.. ;J-

. n y.- <:

i  ;::c,mN.c;. .g. e:

, y, . -

' c.as.a .

. . ' (.y r - '

yy: .

Q < ,_

m:.e

. . . .c ., - -

, , , .;a i ' - :'

.. f ;.. 7%_ ';; :. -

, r;;.3 ;

i:

. I,4 .y;-i d .. .

.3 -

., -: Gr. : ' ' ,'

+

;,\; ,.. y

,.- .. . .: 3 n,.--;;- M, .-

l,.

c; .'@

~ '

E!

o Q . .c p :..- . . -

..m'. .:;.. r .4 c -i.' .-.:s. f ?. - T,.

1,..

3

. . ; 7, . .z. _ . . .. .. ..

w m

h.

r ,

j i

j Figure 3-5 OD radial metallography showing intergranular cellular corrosion

(ICC) present along with the more dominant axial intergranular

{ stress corrosion cracking (IGSCC) at the first tube support plate j (TSP 1) of Tube R8C60. 16X Mag. 2% depth.

j s:\ ape \tva96\u2cy8_90d.wp5 3-27 i

1 i

1 i

i i

4 i

! t en

~c l .

h

=

i E-r:k ,:'/,- b

{

l 4 .-

• L

.j; .g

,,,(#

1 ;-; , ?;. ,,

'$.:f:Y .:.c.

[

s-

.,j% ?2i' ?iQf7., I Wy,M::,; (

. .,N

.u,-

I'

?'); - "

. i, a, L.%,._%.8..

. $, n ..0 .

T5 . "f ' :h, , .'l'iQ; li:l' j(;Q';M , Ej

' q. Q  : .

.,. x. -

sti hy,;

D .yJ l .

...w7. , t!.}'.g s.

Nr . 44, -

3. .

n ;, . .

' yp., y::.O.ny 4 '

1 * , ' '..ki Y:; ~,;,. 3-7,, , .s Di { ,fL ., .

! 10 ' 'n m #v v6p$.;.-@g.

di . vn;i.

E4. , w -_ i9:R' .. pt. m j '1'%. , ' ,,2 ,

j: ' *flg,3,n,p l .

e2 .J ,; *W'-

C i ,

• ,", . ,4 92.

w g 5. ,g

,. np

.c.r.(p(.n-

'

'z

,. y: , . -l.y;  ;:

i ..

"V %:M Q i k. =. . t ; M.' '

. d ff%~ H Ih[" y'%J."-).. O T.?h.rsJiiT.YQffI lE fM,..ST.&"W S I .. . . .

-n- '

L4 4 F wi'~

! V

.M

i 1

& k4y; 4 #.m; 4; .

i w kt.:.15 B

.f':.W:f)g::c%s. c k

y!'

y , *.j;g.; o

. .'* f mm 1lt..T.,s.. : t. . .L->

~'

'g. 4 .. ~ .. , t t

i d

i i

1

Figure 3-6 OD radial metallography showing intergranular cellular corrosion

{ (ICC) present along with the more dominant axial intergranular

stress corrosion cracking (IGSCC) at the second tube support plate

! (TSP 2) of Tube R8C60. 16X Mag. 2% depth.

)

s:\ ape \tva96\u2cy8_90d.wp5 3-28

a Figure 3-7 Sequoyah Unit 21996 Pulled Tube go Plus Point Depth Profile - R8C60 Indication at TSP-I 80 ,

.U - - O - - + Point

. -e-Destructive Exam DG . l 70 l

g. D-a,,*l7 ,-_~ '. ,

= .

= .

_ 60

$ =

.c:

g

[C50 '

Id. _ = : -

= - /.

O U

\'J k I + Pt DE 4 40 --

8 ." Max Depth 82% 60.0 %

H Length .38 .523 30 -

II Avg. Depth 48.7 % 33 6 %

I--s-a.l.l-I 111

\\

20 -p 10 -

8

.* . M O si sii  :: -

is _

-0.3 -0.2 -0.1 0 0.1 0.2 0.3 Axial Distance TEN 0860.XLS:ChR08C60:8/20/% 3-29 .

t i

'6 M t r u E Y e 0e e S C T I [

u l

S M 0 0

+ 2 e l m m E L

lj A R I f t

t t M I

T 0 e D i

[

ll 8 0 C 1 2 f 3 5 t 2 4 E N s  : 'E F F f F m e 5 u E l E

T /

s 2

2 M m M l a 1 80fe l t 0 N f e N E T ) I OS O 5 I

• 4 B R I M u B a

1 0 s f m m u T

• • y a

G B

: f MIR :

A TEl t 5

5 u t

t m

lllT I t

L A

NI tTi C [ N R a

5 t a I E N 8 f

e e S U 3 gI R d 5 E T f

i t

/

5 I

L f

5 t T i

n 1

b e I 0 8 - b S S S

5 -

o B

2

{ F d l

i F

f e

k a

h e o sf f

3 4

Ef 0 f 3

2 i s

s a t 1 - s e

+B 0S 8

y 1

M I

g l aC 5C a s

5 n a

~g F R e

3 3

8 4

8 p

p

] 1 3

E 5

4 I

U p

p t

y r

o a

r E V o e 4 1 b 2

M 5 5 1 a 0 L 3-f o 3 5 b{ F l t

s u

a s k e 5 t 3 e t 1 5

sf e fa e

i t

R s 0B 2 g  :

1 n g 3 a 1 g

g 1

m 3 C MC a

P S

4 0

L T] 7 2

T T 0

6 C

8 1

8 3

5 p p

3 8

U p

p R 2 V E 3

G S

3 W1 I  :

8 I _ 8-3 e

r 5 p

u g

w .

- d WI 8

l a _

$ i F

0 9_

8y 8

2 u

\

6

, - 1 - _. _ - - ~ - ~ - _ - . - 9

~ ___- _

a 1 3 P# [*QE v OY4U 00NO \

t e

p a

\:

s

1

• 1 1

l l

E E SI h h hI E! I

. a g n 1- ECUCI m j = 3 T 3 2 u l ! -

s = --eg

- e a - =

=  ;; _g

! E E -

~

i F' 55$c .$

7- " d 55----: c a A 3 =

.a

- = = = -

3

2 r ,

3 g 3 K lL $  !

I e

'.8

• 1 1

2 2 -

m "t - "t Is a .:?

Is _

i e c l w no C c5

= ,

o L

c- tr* b 1 s

4 - e 2 1 3 J 2e 2 8 5 4 l H 5 w $.

C CQ A

Y J E

M

=- ~

~

s a

[3 si 4 .- u 5 m m

l

=w -

= E+

/ ^ o r o O

c 3 m M

d ,

_ " t co ,

• e > i 0

w e.

en 1

~

4 ,

] c I n

==

3 8

i ..,I . .

.,,,...t . , j

• I , . . . i , , , , I ,,, .

EC175 08/09/96 14:28:31 1 u

i s 40s the ge 38V E8W 3.45 M i I:5 10 5.82 5Eman Rese-= [et m< .

51 C 1 taff C 1 Ostf

1 1: I RIEL M E DISE MIa 5IDE K

{ 5/E emuuttem SUTLET IC l l:l lIN

- EXTENT TEN l TEM jQt N M SPEED *****lsm/ses lTRAt>

NDD set V,, e.33 Lugg 3e m V,, e.se M 32 is.J n., e e5-27 22 isss cunt sosetu-2 rateutucy a=

e s  ; m .< _ =

BCNTE: 8 F3 lee INTERP: OFF F4 le RATE: 80s

- /

100 19.25 3 5 tes Ehz Ito 89.25 3 3 200 Kha C t Estr C t Otfl rn a -

r -

4 O -

CD -

N -

r -

m N -

W -

e.53 Lggg255 et Vpp e.48 Lilgit? 552 m .

V,,

r : i m  %

( -

& or-- r n

- n _m m o e m

^ 5

" ~

u : ~

to Figure 3-10 SG 2 R4C23 TSP 1: Results of Laboratory Reanalysis of Field Bobbin data a:\ ape \tva96\u2cy8_90d.wp5 3-32 .

e 5.52 5 1 400 thz 40 l col  : !W 5IV t.45 It i 1:5 to SE em 30H- = CeL e< :

C 1 Saff C I Baff 1: 1 I: 1 EffL E LE 8ISE MIE 519L K 7 5/E e m enti m m SuiLET l:l

~~ ~ ~

fC l lIN LIT [MT IIN l T[lt l I N f1 SP[ED *** **l t e/ses lTEAtu

__ _- g Vpp 4.42 g 145 m vpp 4.45 M 147 23I NN 8 45 2h22 im CUAL 8088tu-2 Rf0uthty 7 R 2

. M .V EinRn: 8 f2 290

,M --- - c; _x w __

F3 tee e

SENTE:

% "N

/ RE

\

30s 84.25 3 5 800 Ehm 100

~

14.25 a 3 20e Ehm C I 8str C 8 Entf

~_

m n -

~

V u -

m -

O -

Co -

H -

m -

s -

@ er 3 232 m 12 41 Vpp 9.17 m _

Vpp t.43 e

^

\ l

[

1. k  %

~

O U-O - U _ _. _A U 4

5 -

Figure 3-11 SG 2 R4C20 TSP 2: Results of Laboratory Reanalysis of Field Bobbin data s:\spc\tva96\u2cy8_90d.wp5 3-33 .

Figure 3-12: Burst Pressure vs Volts for 7/8" Alloy 600 SG Tubes Additional Data, Reference Gr = 68.78 ksi @ 650 F 12.0 10.0

- Reference Database m W2 Additional Data ,

t N -

Regression Curve i

~ _ __

" N s .

N

.,.' ------ 95%/90% Tol. Band 8.0 ' - '

m

.. ..,' w s -

y ... .

. X, ...

2 N

g -

N .

g 6.0 x -..

m u .., .., -

x N

. . N ,-

._ l

$ 4.0 N

- x

.' . , N N

s

_ _ _h s 2.0 . '

0.0 0.1 1. 10. 100.

Bobbin Amplitude (Volts)

[788V_896.xis] Tol.BW 3-34 RFK: 8/21/96. 2:13 PM

Figure 3-13: Burst Pressure vs Volts for 7/8" OD Alloy 600 SG Tubes Reference Database, Reference or = 68.78 ksi @ 650 F 12.0 EPRUNRC Database a Additional Data 10'0 Regression Curve N es -

--- 95% Prediction @ LTL u N + New Regression N +g O . x New 95% Pred @ LTL 8.0 x ,,,* ' x '

$e n.' ,

u 1g N 5

6.0

'x- m N --s g

'* \

4 u x'v __

N. _ _

m ^%.

'X h 4.0 -

x' x.

x+S 'N-s 3.657 ksi --- - - --'--'-- -

,%x,. -x +

j .,,g~ 3.N_

y~

2.560 ksi - - --- '-- -- ----- ---' -------- - - - - - -- - - - ' --- -- --

---?

~ -% - x

' x 2.0 - .

X l .X -

. i -x 8.84 V 28.10 V -- - -

1 0.0 O.1 1. 10. 100.

Bobbin Amplitude (Volts) .

RFK: 8/21/96,2:14 PM

[788V_896.xis] BvsV.NRC

Figure 3-14: Probability of Leak for 7/8" SG Tubes Effect ofInclusion of Additional Data 1.0 ,. . .

0.9 EPRUNRC Database /

m Additional Data /

0.8 m + POL EPRUNRC Data )

[

d 0 .7 w/ Additional Data /

E c

• 0.6 [

E ]

j 0.5

• E D 0.4 E

g 0.3 0.2 0.1

=- -

/

0.0 - -

0.01 0.1 1.0 10.0 100.0 Bobbin Amplitude (Volts) .

178PV_896.xts] PollogM i3 bhh MK: 8/21S6,2-13 PM

1 l

4.0 EOC-7 INSPECTION RESULTS AND VOLTAGE GROWTH RATES 4.1 EOC-7 Inspection Results In accordance with the Generic Letter 95-05, the inspection of the EOC-7 Sequoyah Unit-2 SGs consisted of a complete,100% Eddy Current Test (ECT) bobbin probe full length examination of all hot leg and cold leg tube support plate (TSP) intersections in the tube bundles of the four SGs. A 0.720 inch diameter probe was used for all hot leg and cold leg TSP indications where APC was applied. A total of 366 axial TSP ODSCC indications were found in all four steam generators in the current inspection, ofwhich only fourindications had a voltage above one volt and none above two volts.

Therefore, no tube repairs were made because of ECT voltages exceeding the 2 volt repair limits. An augmented RPC inspection was performed consistent with the Generic Letter 95-05 requirements. The augmented RPC inspection using the + Point probe included examination of all TSP intersections in all four SGs with a dent  ;

voltage over 5.0 volts. In addition, a total of 79 mixed residual signals with a  !

bobbin voltage above about 2 volts were also inspected with a pancake coil; none had i a flaw-like signal. There were no RPC circumferential indications at the TSPs, no  !

RPC indications with potential PWSCC phase angles, and no indications extending i beyond the TSP edges. No flaw indications were found in any dents above 5 volts. I All RPC responses were consistent with that expected for ODSCC at ' TSP l Intersections.  :

i I I A summary of EC indication statistics for all four SGs is shown on Table 4-1. The I j - table shows the number of field bobbin indications detected during the current (EOC-

7) inspection, the number of these field bobbin indications that were RPC inspected,

the number of RPC confirmed indications, the number of repaired indications, and i the total number ofindications in tubes returned to service for Cycle 8 operation.

l Bobbin voltage distribution for all indications detected during the current inspection j l is also shown in graphical form in Figure 4-1.

J Overall, the combined data for four SGs of Sequoyah Unit-2 show the following.

[

• A total of 366 indications were detected at the TSP intersections during the EOC-7 inspection, and they all had a bobbin voltage below 2 volts.

i

• Of the 366 indications detected during the EOC-7 inspection, a total of 12 were RPC inspected.

j

• Only two indications were RPC confirmed (both below 2 volts).

i

• Two indications were removed from service due to tube being pulled to confirm j ODSCC, and the remaining 364 indications were returned to service for Cycle

8.

I E

s:\ ape \tva96\u2cy8 90d.wp5 4-1

__ . .- .- - -. . - . . _ . . . = _ . , .

i

! A review of Table 4-1 indicates that SG 4 had the largest number of indications at EOC-7 (a quantity of 170, all below 1.0 volt), thereby it potentially could be the limiting SG at EOC-8. Two indications above 1 volt were found each in SGs 2 and 3, and the largest bobbin voltage measured is 1.65 volts (in SG 2).

The distribution of EOC-7 indications as a function of support plate location ie

summarized in Table 4-2 and illustrated in Figure 4-2. 326 out of 366 indications 4 were found at the hot leg intersections, of which 254 indications (about 78%) were at the first two TSP intersections. The remaining 40 indications were detected at the cold leg TSP intersections, of which 24 were at the first two TSPs. Eight cold leg indications were tested with a RPC probe; they were all NDDs. This distribution indicates the predominant temperature dependence of ODSCC at Sequoyah Unit-2 l and is consistent with the pattern generally found in other plants,i.e., ODSCCs are

found mostly in the first few hot leg TSPs.

4.2 Voltage Growth Rates For projection of leak rates and tube burst probabilities at the end of Cycle 8 i operation, voltage growth rates were developed from EOC-7 inspection data and a l reevaluation of the same indications from the EOC-6 inspection EC signals. Table 4-3 shows the cumulative probability distribution of growth rate per EFPY for each Sequoyah Unit-2 steam generator during Cycle 7. These growth data are also plotted

in Figure 4-3. Among the four steam generators, SG 2 has a slightly larger average

! voltage growth during Cycle 7, and it also has the indication with the largest voltage growth. The curve labelled ' cumulative'in Figure 4-3 represents averaged composite

! growth data from all four SGs.

R

! Since only a small number ofindications were found during the previous inspections,

! no historical growth data is available for Sequoyah Unit-2. Therefore, in Figure 4-4 j the growth rates for Sequoyah Unit-2 are compared with those for Cycle 7 operation of Unit-1 as well as those for another plant with Model 51 SGs that has also i implemented APC. Cycle 7 growth rates for Sequoyah Unit-2 are slightly higher i

than those observed for Unit-1; however, relatively fewer indications were found in j the Unit-1 Cycle 7 inspection and the Unit-1 growth rate distribution shown in Figure 4-4 is based on data from only 43 indications Thus, no firm conclusions can

, be drawn regarding the slight differences noted in the growth rates for the two units.

The average growth rate for Cycle 7 of Unit-2 is about 2/3rds of that found for Plant A during the cycle in which APC was applied for the first time (the cycle in which significant number ofindications appeared at the TSPs). The design-basis hot leg temperatures for Sequoyah Unit-2 and Plant-A are within about loc and, thus, it is meaningful to compare the growth rates for the two plants. In general, growth rates for TSP indications decrease significantly a few cycles after APC is applied initially i (i.e., a few cycles after a significant number of TSP indications appear the first time).

j For example, between first time and third time application of APC for Plant A the s:\apc\tva96\u2cy8.90d.wp5 4-2

! . , j i

l average growth rate, decreased by about 2/3rds, as evident in Figure 4-4. Thus, l growth rates for Unit-2 may also decrease significantly in the next few cycles. The

! Sequoyah Unit-2 average growth of about 60% (Table 4-4) applies to very small BOC

! voltages (364 of 366 BOC volts are below 0.75 volt) for which percentage growth is l high while changes in voltages are small (0.12 volt average). The maximum growth value of 0.7 volt is smaller than found in most APC applications.

! The NRC guidelines in Generic Letter 95-05 stipulate that a plant-specific growth rate distribution used in SLB leak rate and tube probability analyses to support APC l application must contain at least 200 data points that are established using bobbin

! voltages measured in two consecutive inspections. As the Sequoyah Unit-2 Cycle 7 i composite growth data contain 366 data points established using reevaluated voltages i

from EOC-6 and EOC-7 inspection data, they meet the above NRC requirement. l Thus, Cycle 7 growth can be used in the Monte Carlo analyses to project SLB leak i rates and tube burst probabilities at EOC-8. The analysis methodology described in l Reference 9.3 requires the use of the more conservative of composite growth rates and l SG-specific growth rates in the Monte Carlo analysis for a specific SG. Since growth rates for SG B are higher than the composite growth rates, they were imposed on all four steam generators to provide a conservative basis for predicting EOC-8 performance.

4.3 NDE Uncertainties The NDE uncertainties applied for the Cycle 8 voltage projections in this report are documented in References 9.2 and 9.3 and they are consistent with NRC GL 95-05 (Reference 9.1). The probe wear uncertainty has a standard deviation of 7.0% about I a mean of zero and has a cutoff at 15% based on implementation of the probe wear standard. The analyst variability uncertainty has a standard deviation of 10.3%

about a mean of zero with no cutoff. These NDE uncertainty distributions, presented in Table 4-5 as well as graphically illustrated in Figure 4-5, are included in the Monte Carlo analyses used to predict the EOC-8 voltage distributions.

I s:\ ape \tva96\u2cy8.90d.wp5 4-3

Table 4-1 Sequoyah Unit 2, May 1996 Outage Summary ofInspection and Repair for Tubes in Service During Cycle 7 Steam Generator 1 Steam Generator 2 Steam Generator 3 In-Semce During Cycle 7 In-Service During Cycle 7 In-Service During Cycle 7 vdese w ,,c ,,e , w w ,,c ,,e . Rw w ,,g ,,c ,,,,,,,,,,

Rw Inspecied Confumed Repoised laspecied Confirmed Repairmt leW Confinned Repend 0.2 4 0 0 0 4 5 1 0 0 5 7 0 0 0 7 0.3 18 0 0 0 18 9 0 0 0 9 19 1 0 0 19 04 13 0 0 0 13 12 5 0 0 12 14 0 0 0 14 0.5 5 0 0 0 5 16 2 O I 15 18 0 0 0 18 06 3 0 0 0 3 8 0 0 0 8 18 0 0 0 18 0.7 0 0 0 0 0 5 0 0 0 5 7 0 0 0 7 08 1 0 0 0 1 0 0 0 0 0 6 0 0 0 6 0.9 1 0 0 0 1 I O O O 1 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 I O O O I 1

O O O O O I O 9 0 1 1 1 1 I O I.I 1.6 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 1.7 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 Total 45 0 0 0 45 58 8 0 1 57 93 I I I 92

>lV O O O O O 2 0 0 0 2 2 1 1 I I Steam Generator 4 Combined Data from All Four SGs In-Service During Cycle 7 In-Semce During Cycle 7

' M- RPC RPC Indmenons Vdase RPC RPC Inspeceed Conrwinal Repewed Inspected Confinned Repened Bm 0.2 12 0 0 0 12 28 1 0 0 28 0.3 36 1 0 0 36 82 1 0 0 82 04 40 0 0 0 40 79 5 0 0 79 0.5 37 0 0 0 37 76 2 0 I 75 06 18 0 0 0 18 47 0 0 0 47 0.7 12 1 0 0 12 24 1 0 0 24 0.8 6 0 0 0 6 13 0 0 0 13  !

0.9 5 I I O 5 8 I I O 8 I 4 0 0 0 4 5 0 0 0 5  ;

I.I O O O O O 2 1 I I i 1.6 0 0 0 0 0 1 0 0 0 1 1.7 0 0 0 0 0 1 0 0 0 I Total 170 3 1 0 im 366 12 2 2 364

>lV O O O O O 4 I I I 3 e

auseGft MLSTaps +4 e1Me4es paa 4-4

Table 4-2 (Sheet 1 of 2)

Sequoyah Unit-2 May 1996 TSP ODSCC Indication Distributions for Tubes in Service During Cycle 7 Steam Generator 1 Steam Generator 2 Steam Generator 3 Tuk Number Number Number Maximum Average Largest Average Maximum Average Largest Average Maximum Average Largest Average Support g g g

• • * ' *E' " ' *E ' *E " **

Plate E* *E Indications Indications Indications 1101 11 0.72 035 035 0.12 19 0.83 0.48 0.61 0.18 42 1.53 0.53 0 54 0.22 1102 9 0.54 035 0.42 0.08 16 1.65 0.53 0.91 0.24 19 0.73 0.45 0.28 0.12 1103 0 - - - - 3 0 45 0.42 0.09 0 03 2 08 0.51 0.45 0.26 1104 3 0.48 035 0.25 0.09 5 0.49 0.28 0.1 -0.01 8 0.8 0 41 039 0.11 1105 10 0.86 0.42 0.41 0.14 4 0.67 035 0.43 0.12 8 0 62 0 44 03I 0.12 1106 3 0.42 038 0.23 0.18 0 - - - - 4 0.44 0.29 0.15 0.04 1107 o . . . . o . . . . 0 . . . .

C07 1 0.29 0.29 -0.03 ~ -0.03 1 1.05 1.05 038 038 1 0.18 0.18 -0.01 -0.01 C06 1 0.13 0.13 -0.09 -0.09 1 0.21 0.21 0 07 0.07 0 - . - -

C05 o . . . . o . . . . 0 . . . .

C04 1 03 030 0.11 0.11 1 039 039 0.21 0.21 0 - - - -

CO2 2 0.25 0.25 -006 -0.10 6 0.44 0.39 0.25 0. I I I O 25 0.25 0 04 0.04 COI 4 0 29 0.26 0.27 0.23 2 031 0.25 0.21 0 08 8 034 0.27 0.25 0.11 Total 45 58 93 4-5

Table 4-2 (Sheet 2 of 2)

Sequoyah Unit-2 May 1996 TSP ODSCC Indication Distributions for Tubes in Service During Cycle 7 Steam Generator 4 Composite of All Four SGs Tube Number Number Support Maximum Average Largest Average Maximum Average Largest Average Plate Voltage Voltage Growth - Growth Voltage Voltage Growth Growth 110 1 98 0.98 0.46 0.62 0.18 170 1.53 0.47 0.62 0.19 1102 40 0.85 0.42 0.77 0.20 84 1.65 0.44 0.91 0.18 1103 8 0.53 036 0.22 0.13 13 0.8 039 0.45 0.13 1104 4 03 0.23 0.1 0.04 20 0.8 033 039 0.07 1105 3 0.5 0.35- 0.26 0.17 25 0.86 0.40 0.43 0.13 1106 6 0.85 0.41 0.26 0.18 13 0.85 037 0.26 0.13 1107 1 0.81 0.81 0.29 0.29 1 0.81 0.81 0.29 0.29 C07 0 - - - -

3 1.05 0.51 038 0.11 C06 1 0.24 0.24 -0.04 -0.04 3 0.24 0.19 0.07 -0.02 C05 5 0.55 0.43 0.18 0.09 5 0.55 0.43 0.18 0.09 C04 3 033 0.25 0.12 0.08 5 0.39 0.29 0.21 0.11 CO2 1 0.21 0.21 0 0.00 10 0.44 0.33 0.25 0.05 Col 0 - -- - -

14 034 0.26 0.27 0. I4 Total 170 366 c owmnawnnumum .' -

4-6

Table 4-3 Sequoyah Unit-2 M'ay 1996 Growth Rate Distribution per EFPY for Cycle 7 Steam Generator 1 Steam Generator 2 Steam Generator 3 Steam Generator 4 Cumulative l

Volts No. of ' ' ' '

CPDF CPDF CPDF CPDF CPDF Obs Obs Obs Obs Obs

-0.1 2 0.044 1 0.017 2 0.022 1 0.006 6 0.016 0 13 0.333 9 0.172 15 0.183 13 0.082 50 0.153 0.1 8 0.511 17 0.466 25 0.452 54 0.400 104 0.437 0.2 14 0.822 22 0.845 31 0.785 68 0.800 135 0.806 0.3 6 0.956 5 0.931 10 0.892 25 0.947 46 0.932 0.4 2 1.000 2 0.966 9 0.989 7 0.988 20 0.986 0.5 0 1 0.983 1 1.000 1 0.994 3 0.995 0.6 0 0 0.983 0 1 1.000 I 0.997 0.7 0 1 1.000 0 0 1 1.000 Total 45 58 93 170 366

)

e GROWTil XLs TmNe4 3 t/19/96 3:42 PM

~

7 ,

_ _ _ _ _ . - _ _ _ _ _ _ _ _ - . _ _ _ _ _ _ _ - . _ _ _ _ _ _ _ . _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___ -__ _ _ - _ _ _ _ --M

~

Table 4-4 Sequoyah Unit-2 May 1996 Average Voltage Growth During Cycle 7 Voltage Number of Average Voltage Range Indications BOC Entire Cycle Per EFPY ' Entire Cycle Per EFPY '

Composite of All Steam Generator Data Entire Voltage Range 366 0.27 0.161 0.122 59.9 % 45.4 %

V soc < .75 Volts 364 0.26 0.161 0.122 60.8 % 46.2 %

2.75 Volts 2 1.01 0.155 0.118 15.4 % 11.7 % ,

Steam Generator 1  ;

Entire Voltage Range 45 0.23 0.112 0.085 47.6% 36.1%

V ooc < .75 Volts 45 0.23 0.112 0.085 47.6 % 36.1%

2.75 Volts 0 - - - - -

Sleam Generator 2 Entire Voltage Range 58 0.29 0.158 0.120 54.2 % 41.2 %

V noc < .75 Volts 58 0.29 0.158 0.120 54.2 % 41.2%

2.75 Volts 0 - - - - -

Steam Generator 3 Entire Voltage Range 93 0.29 0.162 0.123 55.0 % 41.8%

V soc < .75 Volts 92 0.29 0.159 0.120 55.5% 42.1%

2.75 Volts 1 1.06 0.470 0.357 44.3 % 33.7 %

Steam Generator 4 Entire Voltage Range 170 0.26 0.174 0.132 68.1% 51.7*A V soc < .75 Volts 169 0.25 0.176 0.134 70.0 % 53.1 %

2.75 Volts 1 0.95 -0.160 -0.121 -16.8% -12.8%

1. liased on Lycle / duration 01454 Lt PU (4.32 42 PY )

GROWTH XLSITable-4-4i8/19/96[3.42 PM ,

4-8

Table 4-5 i

Probe Wear and Analyst Variability - Tabulated Values i

Analyst Variability Probe Wear Variability Std. Dev = 10.3% Mean = 0.0% Std. Dev = 7.0% Mean = 0.0%

j No Cutoff Cutoff at +/- 15%

j Value Cumul. Prob. Value Cumul. Prob.

-40.0% 0.00005 < - 15.0% 0.00000

-38.0% 0.00011 -15.0% 0.01606

-36.0% 0.00024 -14.0% 0.02275 )

-34.0% 0.00048 -13.0% 0.03165 i

-32.0% 0.00095 -12.0% 0.04324 j -30.0% 0.00179 -11.0% 0.05804 i -28.0% 0.00328 -10.0% 0.07656

-26.0% 0.00580 -9.0% 0.09927

-24.0% 0.00990 -8.0% 0.12655

-22.0% 0.01634 -7.0% 0.15866

-20.0% 0.02608 -6.0% 0.19568

-18.0% 0.04027 -5.0% 0.23753

- 16.0% 0.06016 -4.0% 0.28385

-14.0% 0.08704 -3.0% 0.33412

-12.0% 0.12200 -2.0% 0.38755

-10.0% 0.16581 -1.0% 0.44320

-8.0% 0.21867 0.0% 0.50000 l

-6.0% 0.28011 1.0% 0.55680

-4.0% 0.34888 2.0% 0.61245

-2.0% 0.42302 3.0% 0.66588 0.0% 0.50000 4.0% 0.71615 2.0% 0.57698 5.0% 0.76247 4.0% 0.65112 6.0% 0.80432 6.0% 0.71989 7.0% 0.84134 8.0% 0.78133 8.0% 0.87345 10.0 % 0.83419 9.0% 0.90073 12.0 % 0.87800 10.0 % 0.92344 14.0% 0.91296 11.0 % 0.94196 16.0 % 0.93984 12.0 % 0.95676 18.0 % 0.95973 13.0 % 0.96835 20.0% 0.97392 14.0 % 0.97725 22.0 % 0.98366 15.0 % 0.98394 24.0 % 0.99010 > 15.0% 1.00000 26.0 % 0.99420 28.0 % 0.99672 30.0 % 0.99821 32.0 % 0.99905 34.0 % 0.99952 36.0% 0.99976 38.0% 0.99989 40.0 % 0.99995 GROWTi!.XLS Table 4-5 8/11/9612:08 Phi 4-9

Figure 4-1 Sequoyah Unit 2, May 1996 Outage Bobbin Voltage Distributions for Tubes in Service During Cycle 7 50 40 - -

aSG-1 -----

OSG-2 j 30 - - - -

j OSG-3 5

20 - - - - - - .

MSG-4 __ _

2; r -= ._ _

E 1 ,

10 - - s' - ) -  :

_ k

?

!j -1

=

a 5

" # n 0  :  :  :  :

E

" '=": =

l R  :

l

~

S S $ 5 $ $ $ $ 2 0 U Bobbin Voltage BOBNRPC_XLsFig_4-l]

41Q

_ ___._..__.- .. _ . _ _ . _ .. --..____ _ _.._..._._..._____.. .._______ _.. .__. _ _.. _m _ _ _ _ _ . . _ -

Figure 4-2 Sequoyah Unit-2 Maj 1996 Outage ODSCC Indication Axial Distributions for Tubes in Service During Cycle 7 100 90 80 OSG-A 70 SSG-B 8

y - - . MSG-C __

60 s MSG-D a

% 50 o

D a

E 40 -

z 30 20 -

1 2 =

10 -j _i 5 ' E j m ari a

FL o

i e  ::1 _ r# E .

.n _. __ . _ E 1104 IIO5 H06 1107 C07 C06 C05 C04 CO2 COI 1101 1102 1103 Tube Support Plate GROWHI XI 5 Fig 4-28/12/96 3.34 PM 4-11

Figure 4-3 Sequoyah Unit - 2 May 1996 Outage Cutralative Probabilit- /Growth Rate Distributions for Cycle 7 on an EFPY Basis 1.0 e n -g _ ;; g __ __ _ x x x- x pS#

7. .

• O.9 - -

fe , -

+ ', ( . -

/ - .-

0.8 -

/."

= (

y 2 0.7 - j f

E /

I 0.6 - /

/  : SG1

.2 fj, 4(/ - -+ - SG 2

c 0.5 _

% 4 5 1 - - * - - SG 3 t

y 0.4 - /,t 1

% /

3 // _o_.SG4 E

0.3 - -

// -

U //

/t --x- Cumulative 0.2 - )

.7 9,f 0.1 - --- rf' , -

/

0.0 x#".g .  :  :  :  :  :  :  :

5 oo

~

N. 9 o 9 N 9 9 9 9 m.

o o o o o o o o o

o. o.

Voltage Growth aa= =~ = = ' = 4-12

Figure 4-4 Sequoyah Unit 2, May 1996 Outage Comparison of Cycle 7 Growth Rate Distribution (on an EFPY Basis) with Other Plants 1.0 _

_  ; ; ;

: = = -

+

0.9 - /

't r i t /

0.8 - ,L Il- ---

I

$ I I 0.7 - ' -t-E

= I I sa. t I a 0.6- g-- -l - -x-Plant A (Third Time APC Application) - - -

I I f.c I I g 0.5 - - -l - 0 Plant A(First Time APC Application) --

.n I . I C I 4

,E 0.4 - r --+- Sequoyah-1 --

% I -f 3 I I g 0.3 - l- ,! - +- Sequoyah-2 U

fI' l-0.2 - I I

I 0.1 - ,' -tb 0.0 A- + r, cx=, '4 )'  :  :  :  : : :  :  :  :  :  : :  :  : :  :  :  :  :  :  :  :  :  : :  : :  : :  : :  :

m n - -

o m

o 9

o m

o e

o 9 9 9 m e m m

n m

9 o

m a

e m

m o o o - - - - -

Voltage Growth (per EFPY)

- nw== ' a = 4-13

Figure 4-5 NDE Uncertainty Distributions 1 ,

c;;c00000000 0.9 -- - - - - - - - - -- - - - - - - - -

0.8 - - --

0.7 - -

=

b 25 0.6 - - -- - - - - - -- - - - - - -

E E -e- Analyst Variability 0.5 ~~~ ~~

Probe Wear j 0.4 U

0.3 - -

0.2

?

0.1 0oseeccccccccc^

-40% -30% -20% -10% 0% 10 % 20% 30 % 40%

Percent Variation in Signal Voltage (%)

ng 4-5 Chart i Fig 4 5 Chart I 8/19/96 339 PM 4-14 .

5.0 DATA BASE APPLIED FOR APC CORRELATIONS The database used for the APC correlations applied in the analyses of this report are consistent with those used in the initial APC submittal for Sequoyah Units 1&2 (Reference 9.2) and described in Reference 9.4 as approved by the NRC in GL 95-05.

Per NRC requests, this database has been updated to include more recent pulled tube data from plants P-1 and A-2. (The plant codes used are same as those established for Reference 9.4.) The updated database is given in Reference 9.6.

l l For the SLB leak rate correlation, the NRC recommends that Model Boiler specimen 542-4 and Plant J-1 pulled tube R8C74, TSP 1 be included in the database. This database is referred to as the NRC database and is applied for the leak rate analyses of this report. As noted in Section 6, the leak rate data does not satisfy statistical requirements for a voltage dependent leak rate correlation.

Two hot leg tube segments pulled during this outage (one from SG 3 - R8C60 and another from SG 2 - R4C23), per GL 95-05 requirement, were examined at the Westinghouse Science and Technology center. Results from tube leak test, burst test

! and destructive examinations are summarized here in Section 3. The pulled tube i

exam results were also evaluated for application to the EPRI database for APC application, and it was concluded that inclusion of this Sequoyah Unit-2 data does not significantly affect the existing burst pressure and probability ofleak correlations.

l l

l l

I s:\apc\tva96\u2cy8.90d.wp5 5-1

6.0 SLB #EALYSIS METHODS Monte Carlo analyses are used to predict the EOC-8 voltage distributions and to calculate the SLB leak rates and tube burst probabilities for both the actual EOC-7 voltage distribution and the predicted EOC-8 voltage distribution. These methods are consistent with those described in the generic methods report of WCAP-14277 (Reference 9.3) and the Sequoyah-specific report of WCAP-13990 (Reference 9.2).

Based on the NRC recommended leak rate database, the leak rate data do not satisfy the requirement for applying the SLB leak rate versus bobbin voltage correlation.

The NRC requirement is that the p value obtained from the regression for the slope parameter be less than or equal to 5%. For the NRC recommended data, the p value is about 6.5% and the leak rate versus voltage correlation is not applied. The SLB leak rate correlation applied is based on an average of all leak rate data independent of voltage. The analysis methods for applying this leak rate model are given in Section 4.6 of WCAP-14277 (Reference 9.3). A Monte Carlo analysis is applied to account for parameter uncertainties even though the leak rate is independent of -

voltage, s:\ ape \tva96\u2cy8.90d.wp5 6-1

1

[

7.0 BOBBIN VOLTAGE DISTRIBUTIONS 7.1 Probability of Detection (POD) ,

The number of indications assumed in the analysis to predict tube leak rate and burst probability is obtained by adjusting the number of indications reported, to account for measurement uncertainty and birth ofnew indications over the projection period. This is accomplished by using a Probability of Detection (POD) factor. The calculation of projected bobbin voltage frequency distribution is based on a net total  ;

number ofindications returned to service, defined as follows.

l N

Nrot ars = - Na,, u + No ,,io,,,,,

where:

Nrot ars = Number of bobbin indications being returned to service for the next cycle.

Ni = Number of bobbin indications (in tubes in service) reported in the current inspection.

POD = Probability of Detection.

N,,,u = Number of Ni which are repaired (plugged) after the last cycle.

No ,io,,,a = Number ofpreviously-plugged indications which are deplugged after the last cycle and are returned to service in accordance with IPC l applicability.

4 There are no deplugged tubes returned to service at Sequoyah Unit-2 BOC-8.

The NRC generic letter (Reference 9.1) requires the application of a constant POD 1 value of 0.S to define the beginning of cycle (BOC) distribution for the EOC voltage projections, unless an alternate POD is approved by the NRC. Sufficient data exist  !

now to define an alternate POD based on the past inspection data. A voltage- l dependent POD known as POPCD has been established using data from 11 post-1992 l inspections at 8 different plants. It takes into account newly initiated indications j which are important for APC application. The development of POPCD and  !

supporting data are presented in Reference 9.6. Table 7-3 shows POPCD data as a l function of bobbin voltage and, in Figure 7-1, POPCD is compared with EPRI POD ,

(EPRI POD is based on expert opinion and multiple analysts' evaluations for plants I with 3/4" diameter tubes). It is evident from Figure 7-1 that below about 0.4 volt the  !

NRC recommended POD of 0.6 is non-conservative while it is too conservative above about 0 5 volt. This is also reflectcd in the two BOC-8 distributions shown in Figure t 7-1. It is ofinterest to apply POPCD for sensitivity analysis and compare the results  !

for the case with a POD value of 0.6.  ;

s:\ ape \tva96\u2cy8.90d.wp5 7-1

7.2 Calculation of Voltage Distributions Bobbin voltage projections start with a cycle initial voltage distribution which is projected to the corresponding cycle final voltage distribution, based on the growth rate adjusted for the anticipated cycle operating time period. The overall growth rates for each of the Sequoyah Unit-2 steam generators during Cycle 7, as represented by their cumulative probability distribution functions, are shown on Figure 4-3. The composite growth data with 366 data points meet the Generic Letter 95-05 requirements. Further conservatism for the EOC-8 bobbin voltage prediction is provided by the use of the SG 2 growth rates as they are slightly higher than the i composite growth rates. The methodology used in the calculations of EOC bobbin voltage distributions is described in Reference 9.5.

For each SG, the initial bobbin voltage distribution ofindications being returned to service for the next cycle (BOC-8) is derived from the actual EOC-7 inspection results adjusted for tubes that are taken out of service by plugging. The Cycle 8 bobbin voltage population, summarized on Table 7-2, shows EOC-7 bobbin voltage indicatians, indications removed from service because of tube repairs (all below the 2 volts repair criteria) and the BOC-8 indications corresponding to two values of POD.

The estimated Cycle 8 operating period used in the EOC-8 voltage projection calculations is 457.0 EFPD.

7.3 Predicted EOC-8 Voltage Distributions Using the Monte Carlo analysis methodology described in Section 6.0, analyses were ,

performed to predict the performance of the Sequoyah Unit-2 steam generators at  !

EOC-8, based on the BOC-8 conditions summarized in Table 7-2 and the SG 2 growth l rates (limiting growth rates) shown in Table 4-3 . Calculations were carried out with a constant POD of 0.6, in accordance with the NRC direction of Reference 9.1 as well as POPCD. The results based on a POD of 0.6 are the reference values and those based on POPCD are intended for comparison with the reference results.

As shown in Figure 7-1, below about 0.4 volt NRC recommended POD of 0.6 is non-conservative relative to POPCD while it is too conservative above about 0.5 volt.

Since a large fraction of the indications at EOC-7 are below 0.5 volt, the number of indications at BOC-8 predicted with POPCD is higher than that with a POD of 0.6, as seen in the two BOC-8 distributions shown in Table 7-2.

The EOC-8 predicted APC voltage distributions are summarized on Table 7-3. As l anticipated, the limiting steam generator is SG 4 with about 283 indications predicted at EOC-8 for a POD value of 0.6. The assumed BOC-8 and predicted EOC-8 bobbin I

s:\ ape \tva96\u2cy8_90d.wp5 7-2

frequency distributions for each steam generator are shown on Figures 7-2 through 7-5 for constant POD value of 0.6 as well as the voltage dependent POPCD. The maximum bobbin voltage predicted for EOC-8 is 2.3 volts for POD value of 0.6 and

' 2.2 volts for POPCD.

l j

l i

s:\ ape \tva96\u2cyS_90d.wp5 7-3 j

l l -

l Table 7-1 Comparison of POPCD with EPRI POD POPCD Based on Data from 11 Post '92 Inspections in 8 Plants Voltage EPRI Bin POPCD*

POD 0.1 0.30 0.24 0.2 0.38 0.34 0.3 0.49 0.44 0.4 0.57 0.53 0.5 0.62 0.62 0.6 0.66 0.67 0.7 0.71 0.73 0.8 0.76 0.77 0.9 0.80 0.81 1 0.83 0.83 1.2 0.90 0.88 1.4 0.93 0.91 __

1.6 0.96 0.92 1.8 0.98 0.93 2 0.984 0.94 3 1.00 0.98 3.5 1.00 1.00

' Data Taken from Reference 9.6.

m occ w x T 7.i .i n s u m 7-4 l

I Table 7 - 2 Sequoyah Unit 2 May 1996 EOC-7 Field Bobbin and Assumed BOC-8 Bobbin Distributions in SLB Leak Rate and Tube Burst Analyses Steam Generator 1 Steam Generator 2 l

EOC-7 BOC -8 EOC-7 BOC -8 m D B B Indications R 6 B

indications 7 ,

0.2 4 0 6.7 11.8 5 0 8.3 14.7 0.3 18 0 30.0 40.9 9 0 15.0 20.5 0.4 13 0 21.7 24.5 12 0 20.0 22.6 0.5 5 0 8.3 8.1 16 1 25.7 24.8 0.6 3 0 5 4.5 S 0 13.3 11.9 0.7 0 0 0 0 5 0 8.3 6.8 0.8 1 0 1.7 1.3 0 0 0 0.9 1 0 1.7 1.2 1 0 1.7 1.2 1 0 0 0 0 0 0 0 0 1.1 0 0 0 0 1 0 1.7 1.2 1.2 0 0 0 0 0 0 0 0 1.3 0 0 0 0 0 0 0 0 1.4 0 0 0 0 0 0 0 -0 1.5 0 0 0 0 0 0 0 0 1.6 0 0 0 0 0 0 0 0 1.7 0 0 0 0 1 0 1.7 1.1 Total 45 0 75.1 92.3 58 1 95.7 104.8

> lV 0 0 0 0 2 0 1.7 2.3 Steam Generator 3 Steam Generator 4 EOC-7 BOC -8 EOC-7 BOC-8 Vohage Field Bobbin Indications POD Indications POD Bin Indications Repared 0.6 Repared 0.6 0.2 7 0 11.7 20.6 12 0 20.0 35.3 0.3 19 0 31.7 43.2 36 0 60.0 81.8' O.4 14 0 23.3 26.4 40 0 66.7 75.5 0.5 18 0 30.0 29.0 37 0 61.7 59.7 0.6 18 0 30.0 26.9 18 0 30.0 26.9 0.7 7 0 11.7 9.6 12 0 20.0 16.4 0.8 6 0 10.0 7.8 6 0 10.0 7.8 0.9 1 0 1.7 1.2 5 0 8.3 6.2 1 1 0 1.7 1.2 4 0 6.7 4.8 1.1 1 1 0.7 0.2 0 0 0 0 1.8 0 0 0 0 0 0 0 0 1.3 0 0 0 0 0 0 0 0 1.4 0 0 0 0 0 0 0 0 1.5 0 0 0 0 0 0 0 0 1.6 1 0 1.7 1.1 0 0 0 0 1.7 0 0 0 0 0 0 0 0 Total 93 1 154.2 167.2 170 0 283.4 314.4

> 1V 2 1 2.4 1.3 0 0 0 0 PRfDCOtfp AS Tasse74 trteet 4 44 Pts 7-5

Table 7 - 3 Sequoyah Unit 2 May 1996 Voltage Distribution Projection for EOC - 8 Steam Generator 1 Steam Generator 2 Steam Generator 3 Steam Generator 4 y,3 9, Projected Number ofIndications at EOC-8 Bin POPCD POPCD POPCD POPCD 06 6 6 6 0.2 0.69 1.23 0.87 1.53 1.21 2.14 2.08 3.67 0.3 5.40 8.17 4.19 6.71 7.08 11.05 12.82 19.82 04 13.09 17 % 9.19 12.87 15.27 21.42 31.15 42.74 0.5 16.69 21,49 14.68 18.02 21.67 27.30 46.98 58.15 06 14.95 17.99 17.45 19.16 25.15 28.02 51.39 57.91 0.7 9.76 10.92 16.35 16.60 24.17 24.36 44.15 45.78 0.8 5.67 6.02 12.30 11.85 20.41 19.28 32.59 31.65 0.9 3.37 3.41 7.72 7.19 14.69 13.29 22.25 20.50 1.0 2.14 2.09 4.46 4.06 9.45 8.27 15.11 13.34 1.1 1.45 1.40 2.63 2.36 5.77 4.95 10.21 8.78 1.2 0.78 0.62 1.68 1.45 3.39 2.83 6.61 5.56 1.3 0 00 0.00 1.11 0.93 1.94 1.54 3.91 3.21 1.4 0.70 0.70 0.70 0.56 1.14 0.87 2.09 1.68 1.5 0.30 0.30 0.43 0.33 0.70 0.52 1.00 0.55 1.6 0.31 0.22 0.49 0.31 0.00 0.00 1.7 0.29 0.05 0.40 0.00 0.70 0.70

_ 1.8 0.30 0.00 0.07 0.70 0.30 0.30 1.9 0 01 0.70 0.00 0.00 I'.0 0.00 0.00 0.70 0.00

_ L1 0.70 0.00 0.30 0.30

_ 2.2 0.00 0.30

_2.3 0.30 TOTAL 74.99 92.30 95.67 104.89 154.00 167.15 283.34 314.34

>1V 3.23 3.02 8.46 6.90 14.90 12.02 24.82 20.78

>2V O O 1.00 0 1.00 0.30 0 0 m = - coco - w r. 7-6

Figure 7-1 Comparison of POPCD with EPRI POD POPCD Based on Data from 11 Inspections at 8 Plants 1.0 _ ,,,,____________ _ _g _ _ n x _ _ - -

--o 0.9 x-M " " _ y V'

O.8 0.T 0 E NRC Recommended POD w / N g 0.6 s ?7 a

% 0.5  !?

.I / ,/

3 /

I[

,g 0.4 - - - - - --

,2 ,/[ --x- EPRI POD 0.3 -i/ - -

d ---o -POPCD 0.2 0.1 0.0  :  :  : l l 0 0.5 1 1.5 2 2.5 3 3.5 Bobbin Amplitude PREDCOMP.XLSjFig71]8/19!98i4.45 PM 77 ,

Figure 7-2 Sequoyah Unit-2 SG 1 Predicted Bobbin Voltage Distribution for Cycle 8 i

POD = 0.6 45 0 40.0 i

33 a C BOC-8 l

30.0 I

,j u Predicted EOC-8 l

.. 25 0 E .,

'o 1

20.t t b  :

2 15 0 -

10.0 - - - -

50 - - - - -

0.0 " E " " -

0.1 0.2 0.3 0.4 0.5 06 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 Bobbin Voltage POPCD 45.0 i

40 0 O BOC-8 35 0

, 30.0 m Predicted EOC-8 8

25.0

] l s  !

2 15 0 - - i l

10 0 - - -

l l

5.0 - - - -- -

00 E I- " " -

0.1 0.2 0.3 04 05 06 0. 7 08 09 10 11 12 1.3 14 1.5 i Bobbin Voltage j

- . . . . ~

7-8

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

1

. I l

l Figure 7 - 3 Sequoyah Unit.2 SG 2 Predicted Bobbin Voltage Distribution for Cycle 8 POD = 0'.6 30 f

i

- l 25 l OBOC4  ;

s 20 m

l e Predicted EOC4 5

13

\

l 15 - - -

E 10 - - - --

~

I 5 - - - - -

g E 2 E o

- llli....rt_.

$ E E E $ 3 5 0 7 5 0 I O I O O E E O Bobbin Voltage l

l POPCD so 25 .

OBOC4

~

20 -- -.

$ e Predicted EOC4 5

4 y15 .,

o

! ~

• to __.- _ - _ _ ._

~

5 -.- - - - -- - - - - -

, I r cl_Im . . . _n .. _

o E S o $ $ $ $ $ 3 U C ! O I C I I E N 2 N ,

Bobbin Voltage moeo u 79 e,1=> - ~

Figure 7 - 4 '

Sequoyah Unit-2 SC 3 Predicted Bobbin Voltage Distribution for Cycle 8 POD = 0.6 j 35.o l

9 J

! O BOC-8 25.0 -

j m Predicted EOC 8 . j E

l l j 20.0 - - - - -

, l i3 (  !

s j is.o - - - - - -

l E

I l$ _ =

j 10.0 - - - - - -

I l

s.0 - - - - - - ---

(

J i t .: .: n. .

. . l

: : : as,2,, l POPCD l 45.0 40.0 O BOC-8 35.o  ;

1

, 30.0 m Predicted EOC-8 8 l 2 -

g 25.0 y so.o

- --- - - -I l

= no _ _ - - _ _

1 10.0 - - - - -

N - - e eemm ene em -

! ., t I I . ._ _m . -

l

!  ; ; ; ; : : : : : : : : : - s . . . s - ~

j soddin vo.ao. l moeonus au ~ ~

7 39

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

• l l

l Figure 7 - 5 Sequoyah Unit-2 SG 4 Predicted Bobbin Voltage Distribution for Cycle 8 4

POD = 0.6 i

70.0 i

~

, 60 0 -

l O BOC-8 50.0 - -

'lj 40.0 m Predicted EOC-8 '

- - - I

!4 j 300 - - - - -

j l

! 20.0 - - - - - - '

i 1

l 10.0 - - - - - - -

l

~

1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 lit._

1.1 12 1.3 1.4 1.5 1.6 1.7 1.8 Bobbin Voltage

! POPCD 90.0

~

80.0 l

i 70 0 -

0 80C-8 e0.0 -

1 E Predicted EOC-8 l $ 50.0 - -- -

'3 j

40.0 - - - --

2 30.0 - - - - - -

20.0 - - -

l --- -

31 l j ':  ; i, . . -

0.1 0.2 0.3 0.4 0.5 06 0.7 08 09 to s .1 1.2 13 14 15 to 17 18 Bobbin Voltage mow-u 7-11 m2=> a =

8.0 SLB LEAK RATE AND TUBE BURST PROBABILITY ANALYSES l 8.1 Calculation of Leak Rate and Tube Burst Probability l

l Correlations have been developed for the evaluation of ODSCC indications at TSP locations in steam generators of nuclear power plants which relate bobbin voltage amplitudes to free span burst pressure, probability ofleakage and associated leak rates. The Westinghouse methodology used in the calculation of these parameters,  ;

documented in References 9.2 and 9.3, is consistent with NRC criteria and l l guidelines of Referehces 9.1.

8.2 Predided Leak Rate and Tube Burst Probability Using the Monte Carlo analysis methodology described in Section 6.0, analyses l were performed to calculate SLB tube leak rate and probability of burst values for  !

the EOC-7 condition based on the measured voltage distributions as well as for the projected EOC-8 voltage distributions. The results of Monte Carlo calculations performed are summarized on Table 8-1. Since APC is being applied for the first ,

time, no Monte Carlo projections are available for EOC-7 conditions, so a I comparison of actuals with projections is not possible.

1 1 From Table 8-1 it is evident that SG 4 is the limiting steam generator for both l I

EOC-7 as well as EOC-8 conditions. The limiting SLB leak rate and tube burst probability calculated from the measured EOC-7 voltage distribution are 0.07 gpm and 1.90x10~8, respectively. The corresponding results projected for EOC 8 l condition using the NRC required POD value of 0.6 are 0.19 gpm and 1.90x10'8 .

The resdts for both EOC-7 and EOC-8 conditions are well below the Sequoyah Unit-2 allowable SLB limit of 3.7 gym and the NRC reporting guideline for tube burst probability of 1.0x102. Although a larger EOC 8 indication population is predicted with POPCD, the peak voltages and SLB leak and burst results predicted are lower than those with a POD of 0.6. In summary, the Sequoyah Unit-2 steam generators meet and exceed the APC criteria with a substantial margin.

i J

a:\apc\tvau296\cy8,90 day.wp5 8-1

I l

l Table 8 -1 Sequoyah Unit-2 1996 Outage Summary d SLB Tube Leak Rate and Burst Probability 1

Steam POD Na d Max. Burst Probability SLB l Generator Indio- Volts" Leak Rate ations 1 Tube > 1 Tube epm l EOC-7 Actual  ;

1 1 45 1.1 1.90 x 10'8 < 4 x 1 0-8 <0.01 2 1 58 2.0 1.90 x 10'8 < 4 x 10 8 0.01 3 1 93 1.9 1.90 x 10'8 < 4 x 10'8 0.04 4 1 170 1.4 1.90 x 10 8 < 4 x 10'8 0.07 i

EOC-8 Predided 0.6 75 1.5' 1.90 x 10'8 < 4 x 10-8 0.03 POPCD 92 1.6 1.90 x 10 8 < 4 x 1 0~8 0.03 0.6 96 2.3 1.90 x 10'8 < 4 x 10 8 0.10 POPCD 105 2.2 1.90 x 10'8 < 4 x 10 4 0.09 O.6 154 2.1 1.90 x 10'8 < 4 x 10 8 0.19  !

I 3

POPCD 167 2.1 1.90 x 10 8 < 4 x 10 4 0.17 i 1

8 0.6 283 1.8 1.90 x 10 8

< 4 x 10 0.35 POPCD 314 1.8 1.90 x 10'8 < 4 x 10'8 0.34

' Voltages include NDE uncertainties from Monte Carlo analyses and exceed measured voltages.

l s.\apc\tvau296%cy8_90 day wp5 8-2

9.0 REFERENCES

9.1 NRC Generic Letter 95 05, " Voltage Based Repair Criteria for the Repair of Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress l

Corrosion Cracking", USNRC Office of Nuclear Reactor Regulation, August S, 1995. .

I 9.2 WCAP 13990, "Sequoyah Units 1 and 2 - Steam Generator Plugging Criteria for Indications at the Tube Support Plate", Westinghouse Nuclear Services Division, l May 1994.

9.3 WCAP-14277, "SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP Intersections", Westinghouse Nuclear Services Division, Jan.1995.

9.4 EPRI Report NP-7480 L, " Steam Generator Outside Diameter Stres Corrosion Cracking at Tube Support Plates - Database for Alternate Repair Criteria, Volume 1: 7/8 Inch Diameter Tubing," Revision 1, Lacember 1993.

9.5 EPRI Draft Report TR-100407, "PWR Steam Generator Tube Repair Limits -

Technical Support Document for Outside Diameter Stress Corrosion Cracking at Tube Support Plates, Revision 1, August 1993, 9.6 Addendum to EPRI Report NP-7480-L," Steam Generator Outside Diameter Stress Corrosion Cracking at Tube Support Plates - Database for Alternate Repair Criteria, Addendum-1,1996 Database Update" August 1996.

s:\apc\tvau296\cy8 90 day.wp5 91

Attcchm:;nt 2 l l

l Westinghouse Energy Systems sa 355 j Electric Corporation Pittsburgh Pennsylvania 15230 0355 3

TVA-96-138 Ref: TVA-96-129 l

July 29,1996 l

Mr. Mark Burzynski Tennessee Valley Authority l

Sequoyah Nuclear Plant l P.O. Box 2000 /

Soddy Daisy, TN G7379 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT S/G Tube Integrity Assessment - Revision

Dear Mr. Burzynski:

Attached please find revised Unit 2 S/G Tube Intet;rity Assessment for U-Bend Axial PWSCC Indications.

This revision includes changes discussed between Westinghouse and TVA (D. Hughes).

If you have any questions, please contact the~ undersigned.

Very truly yours, David R. Co lier Project Director TVA Projects cc: D. Lafever D. Hughes, BR-3 A-C D. Goetcheus, BR-3 A-C E. Camp F. Fink Pennwu o Peormance 1522e. doc

' AUS 14 1996 6001Mif

L Sequoyab 21996 Inspection SG Tube Integrity Assessment for U-Bend Axial PWSCC Indications I

k

, 1.0 Introduction

This report provides a tube integrity assessment for axial PWSCO indications found in the small radius. U bend region of Sequoyah 2 in the 1996 inspection. The axialindications

! are dominantly in the Row 1 tubes with only one shorter indication in Row 2 which is i judged not to be a real indication but conservatively plugged. The inspection was 4 l performed with an 80 mil RPC pancake coil with confirmation of the indications including

inspection with a + Point coil. The + Point coil helps to reduce ovality and liftoff l responses in the U. bend and permits improved sizing of the indications.

l The field data analyses included a review of the prior '94, 80 mil coil inspectior. data for i

! indications found in '96. These results permit comparisons of the prior and current

! inspection results and provide estimates of growth in length and maximum RPC voltage.

To support this tube integrity assessrr at, crack depth profiles for the three longest

indications were estimated from the 4 Point inspection results. The depth profiles permit j estimates of the burst capability of the indications, i

{ 2.0 Operating Conditions for Structural Assessment i i

! . The U bend indications are free span indications and the structural margin guideline of ' l

RG 1.121 to accommodate SAPuo pressure differentialis applicable. The steam pressure l for Sequoyah 2 is about 831 psi which results in APuo = 1419 psi and SAPuo = 4257 psi.

, Predicted burst pressures for the U bend indications are compared to the 4257 psi

! guideline for the structuralintegrity assessment.

3.0 Material Properties for Small Radius U bend Tubes Burst pressure analyses given later in this report require the material flow stress. For small radius U bends, the strain hardening from bending of the tubes significantly increases the yield strength of the tubing. Material properties from tube manufacturing data are taken from straight length sections of the tubing and would underestimate the material properties. As discussed below, the increase in properties from tube bending is only partially reduced by the U bend heat treatment such as applied at Sequoyah 2.

The material properties of Row 1 tubes were evaluated as a part of the U bend heat treatment process development. As teceived U bends indicated a yield strength of about 105 ksi. A stress relieved U bend indicated a yield strength of about 97 ksi after one cycle of heat treatment and about 90 ksi after two, five minute cycles at 1500 'F. Only a single heat treatment is applied in the field process such that the yield strength after heat treatment would be expected to be about 95 ksi. The tensile strength is estimated at about 120 ksi and the test data indicates that heat treatment to 1500 'F has little effect on the ultimate tensile strength. Thus, the flow strength would be expected to be > 105

. s%mshemuse ee6 July 8, toes I

e 1 O

ksi following U. bend heat treatment. For the burst pressure estimates of this report, a flow stress of 100 ksi is applied. The material certifications from the manufacturing records show flow stress of 80 to 85 ksi for the straight length tubing of the three tubes analyzed in this report.

The burst pressure correlations used for Alloy 600 tubing were developed for the more ductile range of flow stresses and are known to slightly overestimate burst pressures for strain hardened tubing with flow stresses as high as 100 ksi. The burst pressures for the U. bend tubes analyzed would exceed that calculated for the straight length material properties and be less than that calculated for a 100 ksi flow stress. Therefore, burst pressures are reported for both the material certification properties and a flow stress of 100 ksi.

4.0 U. bend Inspection Results A total of 19 U. bend ID axial indications were reported in the '96 inspection. Table 1 provides a summary of the indications as obtained from analysis of the RPC pancake coil.

Table 1 was obtained from a growth study and also includes a reanalysis of the '94 cycle 6 inspection results for axial length and maximum voltage. The circumferential extent of the indications is also given in the table and represents a measure of the coil resolution as influenced by coilliftoff and permeability effects. A TVA review of the data indicates that the coil responses are sigmficantly influenced by permeability effects particularly for the cycle 6 data. Although the cycle 7 data are appreciably better than the cycle 6 data with regard to the permeability variations, there is still a permeability influence which makes length measurements difficult.

It is seen from Table 1 that there is no significant change in crack length from the pancake coil between the '96 results and the reevaluated '94 data. In some cases, the increase in voltage, indicating a potential increase in depth, may be real although there are a number ofindications with a decrease in voltage between the '94 and '96 inspections. The results clearly show that the indications were present in '94 at comparable lengths to that in '96 and growth, if any, was principally in depth. Thus, the indications did not initiate over the last operating cycle and growth rates, while not adequately quantifiable, are modest for the U. bend indications. The indications have been present for some time and the current inspection results are typical of an " inspection transient" resulting from improvements in the mag biased coils.

The three longest indications are RIC27 and RIC38 in SG 3 and RIC23 in SG 4. These indications have been further evaluated as a part of this study. Demonstration of tube integrity for these indications bounds the other indications since these three indications have both the longest lengths and the highest maximum voltages. In addition, the next longest indication of 0.54" would satisfy the 3APso burst anargin for a tube with a flow stress of 100 ksi even if the crack were assumed to be throughwall. Thus, it is adequate to focus the tube integrity P.ssessment on the three largesc indications.

The pancake coil'96 and '94 responses from the field analyses for the three largest indications are shown in Figures 1 to 6. These results show the same general shape of the indications between the '94 and '96 inspections as indicated by the Table 1 results.

.w % u w+um 2

i The pancake coil response of RIC38 is of particular interest since it shows as series of

! potentialindications spanning an overalllength of about 4 inches. This is shown by the

laboratory reanalysis of the pancake coil data as given in Figure 7. Figure 7 shows at j .least six separable coil responses. It is believed that only a part of the largest amplitude

response (right side of Figure 7) represents a real flaw. This is supported by the

'. laboratory analysis of the + Point data as shown in Figure 10. The + Point coil subtracts

! common responses from the two coils which helps to reduce effects ofliftoff and j permeability. It is seen from the + Point data of Figure 10 that there is only one j

~

sigmficant response spanning a length of about 0.78". The + Point data is used for the  ;

tube integrity assessment discussed later in this report. The + Point response for RIC27  !

l 1s similar to that found for the pancake coil as seen by a comparison of Figures 1 and 9.

1 l The longest reported indication is that for RIC23 in SG 4. Figures 5 and 8 show the field i and laboratory analyses of the pancake coil data for this indication. There is no j significant difference between the two analyses. Figures 11 and 12 show analyses of the +

j Point data for two different views of the indication for comparison with the pancake coil j results of Figures 5 and 8. The + Point data shows an offset of the indication at about the mid. length of the response which is only slightly seen in the pancake response of Figure 8.

i This effect is believed to be likely due to slippage in the probe and the indication is~

assumed to be a continuous axial crack for the tube integrity analyses. The low

amplitude, rounded + Point responses near the ends of the indication are not believed to

! be due to a real crack. For conservatism, the tube integrity analyses are performed with i and without the ends of the response included as the flaw length. i I

j 5.0 Tube Integrity Assessment i

i The crack lengths of Table 1 for tubes R1027, R1038 and R1C23 are too long to establish tube integrity based on a very conservative throughwall crack assumption. For a flow stress of about 100 kai, a throughwall crack length on the order of 0.55 to 0.60 inch would' i approximate the structurallimit for a throughwall indication. Therefore, the tube integrity assessment for these three largest indications is based on depth sizing for the i indications. For small radius U. bend indications, the phase angle response is distorted by liftoff effects due to tube ovality and by permeability effects. These effects are particularly significant for pancake coils but are reduced for the + Point coil. Therefore, only the + i Point inspection results have been used to develop crack depth as a function oflength. l Some distortion remains in the + Point phase angle and it is n====ry to conservatively assign depths by using the phase angle corresponding to the deepest depth in analyzing the distorted phase response. Thus, the depth profiles are expected to be an overestimate of the actual depth 'and result in a conservative tube integrity assessment. The + Point data, as well as a reanalysis of the pancake coil data, were performed in the laboratory to support a 6ube integrity assessment. l l

Table 2 summarizes a comparison of the field calls, the growth study of Table 1 and the laboratory reanalysis results. The laboratory + Point analyses include the average depth and calculated burst pressure as discussed below. As previously noted, the tails of the coil responses are not expected to represent a crack but were conservatively included in the +

Point responses for the tube integrity assessment. This results in the laboratory crack lengths tending to exceed the field calls. The conservatively estimated average depths for

-- - w 3

- I

. j the indications range from 62.9% for RIC38 to 68.7% for R1C23.

The crack length vs depth profiles were used to estimate the burst pressure capability for the indications. The results for the three potentially limiting indications are given in Tables 3 to 5. The burst pressure analysis methodology searches the crack profile for the most limiting length / depth section that results in the lowest burst pressure (weak link using BKH model column in the tables) as well as calculating the burst pressure for the total crack length and average depth. The tables also include a plot of the crack depth profile as obtained from the + Point analyses. For all three indications, the lowest burst pressure results over a section of the crack as determined by the weak link model. For RIC27, the estimated burst pressure is 5.07 ksi which provides significant margin over the RG 1.121 guidelines. The crack length between 0.16" and 1.05" contributes to limiting the burst pressure of the indication. While recognizing that this estimate may be slightly  ;

high due to the low ductility in the U. bend, there is ample margin for uncertainty in the burst pressure analysis. Even if material properties - very conservatively assumed to l correspond to the straight length material certificatica cne burst pressure would be 4.081 ksi which is near to the structural requirement. For RIC38, the estimated burst pressure of the indication is 7.39 ksi and this indication is the least limiting of the three indications. The estimated burst pressure for RIC23, the estimated burst pressure is 5.04 1 ksi with the weak link of the crack occurring between 0.03" and 1.24" of the crack length. i The burst pressure would be 4.23 ksi even for the very conservative application of the l straight length material properties. The expected real crack length (+ Point Run 2 of  !

Table 5) results in a burst pressure of about 5.7 ksi.  !

The maximum depth estimates of Table 2 for RIC27 in SG 3 and RIC23 in SG 4 could have short throughwell cra:k penetration within the uncertainties of the depth estimates. l Operating leakage in thm 3Gs was only a few gpd with the source of the leakage not clearly identified. The crack profiles of Tables 3 and 5 indicate that the potential throughwalllength would be abcut 0.2" and conservatively < 0.3". For a 0.3" throughwall U. bend crack, the operating leakage would be about 0.01 gpm (about 15 gpd) and the SLB leakage would be about 0.06 gpm (about 90 gpd). These smallleak rates do not challenge

. leakage integrity for the Segouyah.2 SGs. ,

1 6.0 Conclusions Based on the above assessments, it is concluded that:

4

• The U-bend indications found in the 1996 Sequoyah.2 inspection satisfy the structural and leakage requirements of Reg. Guide 1.121.

The burst pressures for the U. bend indications exceed about 5 ksi compared to the RG 1.121 guideline of 4.257 ksi.

. The burst assessment includes conservative estimates of crack length and depth.

Steamline break accident condition leakage would be expected to be < 90 gpd which is insignificant compared to allowable leakage under accident conditions.

.---*. mo. = 4

4 Table 1. Summary of U-Bend Indication Growth Assessment Results -

Pancake Coil l

s/23/w 5/G ROW COL LOcN AXIAL CIRC VOLTAGE FYN FLAW EXTENT EX7ENT I1GLU ORInt, CYE CY7 CY6 CY7 CY6 CY7 2 2 21 HD7+8.0 NDD .22 NDD $7 NDD 1.93 AX2 1 23 H07+2.7 .27 .33 68 37 8.37 10.21 YES AX!

1 33 H07+2.7 .35 .23 63 27 2.12 6.15 YE8 AXI 1 34 HD7+3.6 .33 .33 58 40 3.20 4.35 YES AXI 1 40 HD7+2.6 .41 .33 137 11 13.96 9.71 YES AXI 1 48 HD7+7.2 .37 47 43 49 21.77 21.04 YES AXI 1 48 H07+7.2 .33 .33 35 42 8.01 3.01 YES AXI 3 1 2 HD7+7.7 .44 .38 65 65 3.48 7.44 YES AXI i 1 26 HD7M3 .50 .54 55 62 2.49 12.30 YES AXI  !

1 27 HD745 .71 .91 66 57 2.57 21.89 YES AXI 1 29 197+3.5 .56 .51 52 59 11A0 8.M YES CSL 1 29 HD7+3.5 .56 .47 58 39 14.37 6J9 YES CFL 1 38 )#749 1.20 .90 105 95 11A0 18.01 YE5 m i 1 50 }W7+1.5 J9 .39 71 91 5.63 8.97 YES AXI j 1 $9 187+7.5 .18 .30 38 73 3.s6 10.13 YES AX1  ;

1 4- 1 15 137+4.9 .56 .34 90 30 7.17 3Al YES AXr 1 17 19744.5 .48 .38 105 46 10.08 11.22 YBS AXE 1 19 197*4.5 .35 39 $9 49 5.91 4.46 YES AXE 1 23 19744.4 1.41 1.33 75 47 17.00 2tJ8 YE5 AX1 9

b v .

.g I

t Table 2. Sequoyah-2 '96 Inspection: Summary of U-bend RPC and Burst Pressure Analyses ~-

Three Largest Indimtions l t

'96 Inspection '94 Inspection ,

SG Tube Elev. Coil Anal. Length Max. Max. Avg. Ilurst Length Max.

(in.) Volts Depth Depth Press. (in.) Volts (ksi) ,

3 RIC27 7H +3.7 80 Mil Field 0.76 24.9 '

i

, 711+3.8 + Pt Field 4.75 Growth 0.91 21.9 'O.71 2.87 l 711+ G.5 80 Mil r 80 Mil Lab. 0.77 15.8 84 %

+ Pt Lab. 1.42 4.30 100 % . 66.5% 5.07*

l 4.08" t 3 RIC38 711+6.3 80 Mil Field 4.41" 10.1 ,

l 711+ 6.4 + Pt Field 0.26 5.21 i 0.90 18.0 1.20 11.4 j 711+6.9 80 Mil Growth 80 Mil lab. 0.70 11.1 85 %  ;

+ Pt Lab. 0.78 4.15 84 % 62.9*4 7.395 6.30*

l 4 RIC23 711+6.5 80 Mil Field 1.35 28.2 ,

711+6.4 + Pt Field 7.09 80 Mil Growth 1.35 28.6 1.41 17.0

! 7H +6.5 80 Mil Imb. 1.68 17.9 100 %

+ Pt Lab. 1.70 4.44 99% 68.7% 5.04*

4.23" Notes: i

1. Flow stress of 100 kai at R.T. based on material hardening due to bending of tube followed by U. bend heat treatment.

2. Flow stress based on tube material certifications for straight length of tube.

t

3. Total mported length spans a number of individual 80 mil coil responses, most of which are not flaw like in + Point coil inspection (See Figure 7) i i

_ ~ . . .

Tab!s 3: S2quoyah-2, SG 3; Tube R1C27 U-bsnd Axial Crack; + Point Dtta

, , i . , , , ,

OD i t i Rm i Pfsbo i i i St.RT2OP Sf. cort 0875 0.050 0.4125 14326 1 0 9114 73.37 Op. Temp.

Pbar2Pb PO Pp P.s dP.noo I dP stb St.str.hard 80.50 Rm. Temp.

0.000  ! 0.000 2.250 0.831 1.419 l 2.560 l 91.14 Op. Tomo I i i I i -

100.00 i Rm Tomo

+ Point + Point Crack , Crack g Craca Wook unk Using Depths (* O, Deoths DoDths BKHmodel 0%

• 0 X.mu) 0.160 22 % 1 0 03 X. max 1.0'A 52 % 1 00s Length 0.890 60% 1 0.1 Depth 80.1 %

55 % 1 0.13 Pb i Sf 0.056 65% i 0.16 PD.str. hare 5.069 52 % I 0.2 Pb. cort 4.081 73 % I 0.23 sa% 1 0.27 63 % 1 0.3 52% i O 23 eis i 0.37 99% 1 04 97% 1 0 44 100 % l 0 47 99 % 1 05 100% i 0 54 89% 0 57 92% 0 01 69% l 0 64 se% 0 sf 78% 0.71 86 % 0.74 aos 07s aos 0 et 84 % 0M 70 % 0 as 78% 0 91 70% 0 to 48 % 1 0 SS 50 % i 1 01 e4% i 1.0s 0% i 1.22 0% 1.25 ,

70% 1.20 63% 1.32 55% 1 36 83 % 1.30 0% 1 42 D.ava 66.5 % D. awn D.avn L 1.42 L L

..fe.690.... . A 99. . . . .P,0;600, , ,,,,,,,, , ,Pb.,600 , ,,,,,,,,,

_ Rate Psib 0.0 Ratio Psib Ratio Psib Sequoyah, SG 3 Two R1C27 -

100 % y ,

• 1~

/ \_=

~

I -

O / h ,A ,

70% g%-

j '

_. -N .

I\ -

a j _- S 3h , -

b **}&.f!

m- -. ?l ~~'\ Y-.

15 , g _

6 40% : l \ -

I m 1 g -

\

~

20% - -

- + Point Data _

= j i

\s '

0, .

l 0.0 0.1 0.2 0.3 0.4 0.8 08 0.7 0.0 0.9 1.0 1.1 12 1.3 1.4 1.5 -

Length from End of Crack (in.) -

pvaanmain aicrrt s.n e PageI nacnestiss as

i

)

1 Tablo 4: Sequoyah 2, SG-3 ; Tuba R1C38 U-bend Axial Crack; + Point Data l l 1 I l l l 1 I OD t i Rm Pfsbo I i Sf.RT20P Sf. cert. l 0.875 0.050 0.4125 14326 0.9114 77.74 Op Temp l Pbar2Pb P0 P.o P.s dP too CP. stb Sf.str. hard 85.3 Rm Temp 0.000 l 0.000 2.250 l 0.831 1.419 l 2.560 l 91.14 l Op Temp i e i i I i 100.00 i Rm Temp 8

+ Point + Point

1. • 1. rad ra d sak M W ng Lengths Lengths Len9ths Deoths Depths Deoths BKHmodel 0% 0.00 X. min 0.030 l 65% 0.03 X. max 0.750 l 76 % 0.06 Length 0.720 73 % 0.10 Depth 65% l 70 % 0.13 Pb / Sf 0.081 73 % 0.17 Pb.str. hard : 7.386 i 68 % 0.20 Pb. cert 6.300 68 % 0.23 60 % 0.27 65% 0.30 I l 57 % 0.34 I 55 % 0.37 I I 55 % 0.37 I i 65% 0.41 68 % 0.44 76 % 0.47 47% 0.51 50 % 0.54 I 55 % 0.58 ,

84 % 0.61 73 % 0.64 57 % 0.68 68 % 0.71 70% 0.75 0% 0.78 D. avg 62.9 % D.avo D. avg L 0.78 L L ,

Pb.600 0.000 Pb.600 Pb.600 l Ratio Pstb -

0.0 Ratio Psib Ratio Psib i  !

i i e i i i i Sequoyah 2. Tube R1C38 I 100 % j 90 %

80% -

b (x

y 70% -

~I j  %- -\\  ! x_ \ #

M-60% * #

f w' '

T

( #

1 Y I 1

5 50 % r i k 40% -- , \

$ 30% <} $

20% -

.E -+- + Point Data 10% - -

g__

0%

O.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Length from End of Crack (in.)

pvassa m atm.m m esst.e m PageI w m us.**5 *

. Tabb 5: Sequsyah 2, SG-4; Tuba R1C23 U-band Axial Crack; + Point Data l l l l 1 e 1 l OD t Rm Pfsbp i i Sf.RT2OP Sf. cert 0.875 0 050 0.4125 14326 i 0.911e 76.38 Oo Tomo Pbar2Pb P0 P .p P.s cP.nop dP.ste i Sf.str.hard 83.80 Rm Temp 0.000 0.000 2.250 0.831 1.419 2.560 l 91.14 Op Temo i i i # t i 100.00 i Rm Temp

+ Point- Run 1 + Point Run 2 + Point Run 1 Crack Crack Crack Weak Link Using Depths *09" Depths *N Depths b*"9" BKHmodel <

0% 0.00 0.0% 0.64 X.msn 0.030 60 % 0.03 100.0 % 0.67 X. max 1.240 89 % 0.09 87.0 % 0.70 Length 1.210 81 % 0.15 53.0 % 0.74 Deotn 76.2%

63 % 0.220 98.0 % 0.81 Pb / Sf 0.055 41 % 0.28 98.0% 0.84 PD.str. hard -

5.043 75 % 0.34 98.0 % 0.87 Pb. cert i 4.226 84 % 0.41 100.0 % 0.91 1 69% 0.47 100.0 % 0.94 I 86 % 0.53 93.0 % 0.97 1 72 % 0.60 82.0 % 1.01 + Point Run2 81 % 0.67 79.0 % 1.04 Weak Link using 75% 0.73 85.0 % 1.08 BKHmodel 97 % 0.79 70.0 % 1.11 X. min 0.64 99% 0.86 53.0 % 1.14 X. max 1.67 97% 0.92 73.0 % 1.17 Lengtn 1.03 95% 0.99 70.0 % 1.21 Deptn 72.9 %

60 % 1.05 63.0 % 1.24 Pb/Sf 0.063 63 % 1.11 70.0 % 1.28 PD.str. nard ' 5.747 57 % 1.17 25.0 % 1.31 Pb. cert 4.816 60% 1.24 76.0 % 1.34 i 31 % 1.29 73.0 % 1.37 47% 1.36 73.0 % 1.41 60% 1.42 53.0 % 1.44 63% 1.48 53.0 % 1.47 60% 1.54 49.0% 1.50 60 % 1.61 45.0% 1.54 44 % 1.67 63.0% 1.57 0% 1.70 76.0% 1.60 79.0% 1.63 79.0% 1.67 0.0% 1.70

_D.ava 68.7 % D.svg 44.9 % 0.avo L 1.70 L 1.70 L ___

. . .Pp.6pg , , ,, A039,, , , ,PA6,09, ,, , ,0A09, , , , ,P,b;t[0,0, ,

Rabo Psib 0.0 Ratio Psib 0.0 Ratio Pstb i

Sequoyah 2, Tube R1C23-- + Point Data 100%  :

k* -

_ P:W m /< l *}

._t .--,

-- -I -\ A-R &, .l. V . n-

m. + \ f__v q.4.t  ; wc ,  ;  ;

3" 3..

h(l N

4

• Y.hE.I gja,f._ .;

j _..

}..

v

_j --gy-- 1 30, - a w .

.. 1 [  !

20% - - - . + Point. Run 1 -[  !

10% <

~

-o-. + Point. Run-2 i ' --

0.0 0.1 0.2 c.3 c.4 o.s o.e 0.7 c.s o.s 1.0 1.1 1.2 1.3 1.4 1.s 1.s 1.7 t.s Length from End of Crack (in.)

ji)li inlI' k o N k 2R* ye4 gL - N i

! ,,E 2 5

• Nin

(

/

H [

M l i

T l 4 l

E L

l

) I A

R N l I ,

.X ll I .

E c e

l: K /s I

M .

B n n l9 l I -

/

I i

o I H

4 E

l 7

t l 6 I 8 a

c M le H 9 i T B

d I

n E C/

7 f

9 f

N E

1 E M P G ~

d

" S E $

n ]

e L B- I A

X U D 6

A l 8 nenW0 l

i 1 o i3 i 3 D C 8 4

1 l I

e ' : 3 6

k s#

t a u3me c l 8 L

l R

n P

a t

: n nse:i eet ir s S ss serS p

(

a E I

G G

R I

a s ee iei .s nss l jj iii:

t i e 0r .

a say3 n D K t s

ut d I w s t

l ,

e W - ~

i F 6 =

6 2 2

9 7 c x .

%j)./

2 e C n .

I a 2 R h n s K f

. E n e 6 if i i .

2 v ,

b 9 3 D - -- t x

i u I c i E

.i l s

A T 2C a i '

. e m a m

1 r

u e ,

. . (

Lg s m E

n m g 1 o i

2 8 2 c a s-F . , n i 8 ,1 i c

1 v V

6 1

y -

e 4 V 1

(

2: '

~ a2

_ 4 8 ,

1

,al e3p-s"'. % C .

f . .

! Figure 2. Tube RIC27 '94 Field Data, Pancake Coil U-Bend Indication 129 CN I Y CN 6 H 25.69 396 Khr CH 2 3I1 @ E J SG ROM - Cet. 3 4 $

b ,I', ,*,,,,,, REEL _ _ _ Of SK EtE SIDE = = Q T tetettenz 3r SIC M IfNii n fHLET $,

f es. er sten tants: rs p llH ;E

- nin/ttas rtsissau: sernss tasonsel H87 l *3.88 lrl i

[ * - EXTENT, He7 [ HTE TRAIN

[H r

I s j lTRICCERl l ID l AMIAL SPEED 9.87 lIn/sec Q

fit 7 f .

Vpp 2.87 DEG 61 94

• 1 bh ---v g V

i

' d AMIAt. VIEN C

CIRCtNERENTIAL ENT: 55 BEG

! h 2

\

f -

.i.s.

A AMIM. I MCE AXIAL EXT - 9.71 IN l l .

C i H

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . . _ _ _ _ _ _ _ _ . . _ _ . . _ _ _____ ___m___ _ - - _ _ _ _ - -

SEQUQYAH 05/11/96 INLET UNIT: 2 SG: 3 REEL: 3H93 RES E = 5 w -Z <

gg d =2 u- * -

w %

. 5 -

E 4 g - e l

- -  : =.

= @ l 6 W 3 g J " 4 2 g -

.c E5 4 m .

3 n e -

i!

=  ;;

u . < -

C3 2 d

RERR5 [ f

= . -

5 u

o I EY . Y O E!=,5 $ 9

~

c 5 a il.m%

g -

2, 1

=

3 "dC GIE

• I e I  !!

g- t 5 k I m

c P  !

kJ u .\

W ( }

= {

m U

a

=~

l 1

x E. t z i)

~ ' e d ~

M n*2' n * "- _ ........ .. E a d C 4 y av E 5 g

= . -

H

! O M gs u ~

• ~

g 5 d k

=c u E- > U d E

':P l

j

.m .__

~

l l I E -

I EC183 05/1E/96 16:25:57

Figure 4. Tube RIC38 '94 Field Data, Pancake Coil U-Bend Indication m

84 CH I V 016 Y 18.91 300 Khz CH 2 184 @ [ El

]

SC BI-E ROW 3 $

SIN RE c

y

@ - QlV teletIDW:

x no:atien: 41 t

is OUTLET O

M us er Sten tests:

ausmas ersiscan:

38 sisisss e aweses '

He7 l +G.58 j:l k

lIH EXTEHI H07 l HIE [li SPEED 5.08lIn/see TRAIN its ,

ltRICGERl l ID l AMIAL O

Vpp 11.49 DEC 19 94 bas

..V. E ci. _ m < m : 1.s o a

M..

? U EDT.6.5t M7 -

AMIAL TRACE AXIAL EXTs 1.29 IN i k i g I

m

.j Figure 5. Tube RIC23 '96 Field Data, Pancake Coil U-Bend Indication 134! e I Y sEV 39.50 s 2 300 Khz 333 W t J sc u m pon = = cot e i vi I* I *I ',', o 3'

, h,, ,,, REEL EDE0ISKmMSIDEE t notettes: rse S/G majHITem IHLET o us. Dr stas (lats: les K sessumeu rtsisters asusss t essin3e> Me7 jes.4tl:l lIN k 7

818 88' EMIEMI HS7 [ C97 @

c its I l TRIGGER] lIOl OBLIQUE SPEED 9.97lIn/sec  ! RAIN vpp 2s.se etc 32 sei D n w. "

7 BL M AXIAL. VIEN N

d CIRCtHEERENTIAL EXT: 47 DEC g lei

( h,'

J; l

301*E.9I M**

360 t.no O I A

.mt mcc ,

t1 es AMIAt. EXT: 1.35 IN .

). .

Y I ~

b

- u 3 _

a* i M

e SEQUOYAH 08/17/94 INLET UNIT: 2 SG: 4 REEL: 4H74 SEC h i C S-* $ b d E E E

" = I w

ll Im ll il c .:= a.

= g n = G 1 I

. = 3 5 J* W E 8

" a E a l l ..

'M O I l c. E o 3 R $. R I E E -

- m . n

=

i= n a w

- E

- =

8 3 ;r.*Ec- l a s e 1 U .;; I -

I o g3

.x - l 8  !!=j2

.. p ,_

= .. s .

S  !! ! -

. *ssa c E d

$ u""*"E cm:j 5 ,

E la O  :

y 3g 3; .. .......... ......

.iA E '

ie e

v 2 I m

M W

~

0 / s

" N M B Q n )

J l 5 x

• o a

• L[ ~

C 2 j di o g 5 g-~ ~ ~ ' ,5 H 3 8 ~

E W I

n E -

3 W 8

4 4

" ' k/

• 5 5

4 i N E I y I

= i l l l

l

SEQUOYAH 05/11/96 INLET UNIT: 2 SG: 3 REEL: 3H93 DNT

$ 0 Ei$ =" 1 es 8

/

d g g :-

2 5l

?.

~

.I'5

-t "EE  ;- e =.

-, - = .

.. x;

.= a u 0 $ a g __g - --

g.:

.3 5 -

$ g  ! .

[/ /

f S =x5E2 gj 5 y ~ '/jr '\

z.z.

.e aj \.

S 5 5- N.,

8 iiius u 'k

.550I 5

~

1

/

h.5 $((iE g '

<. 'e f g} W gg , / ' '

b

,f

.$ 5

• I $$ '

a .: --

f j'/,' ,

I {/' >

E; m t

% f

• y,j, <; ' L; /

CC

~

E- y/ ' / }.

o a )  %,/

U .

g / ~

Y j ~3 3 E E

                  ;                                                                                                                                    'Y
                                                                                                                                                                               /g 3
                                                                       ]( V                                                                                                    'e.              /,

Cf J ,l

     &          m                            =

l-o h 's > ' . .: E *- A. ..  :.._.._.,.. - ..-._

                  ~

l I

                                                                                                                                                                .s
                  ~j                     l                                                                                                                                  l
                $\                                      $

EC187 05/30/96 10:19:12

SEQUOYAH 05/10/96 INLET UNIT: 2 SG: 4 REEL: 4H83 DNT m iu ju iE zii / H E i  :- si

                                    ~
                                                            /

BI ISill I l s . WI o Ele 2 3 g

                         = =

R E E!E w.m

                                                                 /

R w 5 o N h i I S  : $ hO *EE!

       $                       55                          ,O  '

x its 3 N 3 $ s j .. .. ; 5 EE55 $ . 6~  !!$! 5 h> si -"l 9 \#

      .s.2 4

w

                         -        !- is 88 9 /[#4 .

1 4 A m e u gg E E / nm G , ( p , ,

                                                                                    /         [

9 A / ,

                                                                                                          ?

x ~ ~; E

       $     r, 2                                       l
       ~                                       p-~

W . d I -

a E > -l p.,;p,tj,i,f{,h.

lL

                                             ^
                                                        "'0 W         ,,

l 5 2l i f

lll$'hMigrammemaman EC187 05/29/96 15:55:57

                                                                                                              )

f,  ! SEQUOYAH 05/12/96 INLET UNIT: 2 SG: 3 REEL: 3H97 DNT E g

                              =

1% s-- gLn - u tsa s - a ! M b - c am E Gi = =. m E. m _= . E Ea o s.

• s 5 EM "lEs N u n ,

a s s  : m w a [O z**=3 C

        .e                       u?

A N y sEs- _ 3 .. .. : " ' R  !!EgE $ 6e ..EEus 1 ' 0 === a-

                                  .=
               =O                    $ w E8          W               E      :

g -- d?

          ~u N

m a ,

        *                                                   )                      '

T r- "e e

                      "f                                                                          E 2            ~*

5

• i*

o

        .C            e h         ?

5-N.S m o 3 a

          $           5                               &                                ~
        .9 a            >,

M .. n N i

                      >                    l                                                               !
                      ~z/mwmwmwmwnWmunymb WWWWwowmym)w.                    ,

N e EC187 05/29/96 14:0*:08 t O

SEQUOYAH 05/12/96 I!!LET U!!IT: 2 SG: 3 REEL: 3H97 DNT MO bb !" 8 El$ h 8M= 2 5I A ~1 d 5 E E E M o = o

                            $ R   E N E o             a m      um N                    w 5                            $

E 5

              +

2RE l x u r;g -/

                                                                                                                                                     /

es - - a k kIhj5 '/ el2o i le- ::2" f -- f 4) el 3 $

              %G                                                                 )

oo eo v

                                                                                                                                                            ./

m !el . U == 2 / M n o

                         -                                               5
                                                                                              /

a u ' I ' o , 4 - - . G - < S -9

:- 3 l l I -d!!!!i-n .. l- l! 0 ll l ll ll ll!ll ll!!! Il llIl l l! ! !! l lIl ll l l i

                       .~

l l 4

                      ~ 5 *ngi ii  pn..m, win.m        pf j?%'Einigjij;hihiii[@f""5lldsiti%iiia=a ea'"'
                      *l                                                                     e EC187 05/29/96 13:44:39

ouN^ >m mm OfeMN c~~$..N n m Q dO ;>:;I mO- ujA " 24 a T H l l N H I R K E L ll H A R E T l l I D U M I S O e . H e ,

                         -      E M          l        E T

s E  :

                                                           /

N _E EK T l7 l i n - O S I 3 l R I H H 9 D U 9 E 0 l G E N m P E E m L B l-D T T T N E S D E

                                                                                                                 %-                       7 3

i C o S E E R G

                                      /

S S T E X E P S r' w

                                                                                                             ~qc        .

0-B T s t ] E w n i o R U S A  : o2 w ~ P l E 2 a N

           +                  ze2      5 4 i t

s l f ss 3 3s o

                                                                                                                                     'S 3

t ( i s s y si t s 3 4

                                                                                                                   %x
                                                                                                                      - g*mw l

n3 i 1 a t

• l R

n  : : a nua #' E G A ost n i t r t s t a' G I r R y r n aaf s

t t oi l T

t so s oo t i res e s

                                       .i T ne r h )!

at s r a E t u s oc i n t a g7 a ss b d an st i n iee t LI r t 2 4 a,d n 5 0_ t 6 . - ae 3 DB - L 3 6U 9

                                                                                                                       %nk              e6   0 m

d

           '         I                                                                                                                       3 g

8 , r 3 C h K f C _ C I 0 0 t i 6 1 R t 3D e ._

                                                                                                                                $wx 1                                             a                                                                            _

e m2 C m _ b a P u s _ 3

                                                                                                                                 -m-q.

T -

                       +                                                          -

0 5

                                                                               \                                                      R i

1 l 2 1 2 2 p e r u g 5 V p e4 i

                                                                                            -    =

F V 2: 1 b =r 5kE

_ .?

i 2E1 e2 ?i 3,

                                                                                                 =-                                                      _

V 1 ee EL i? i-2: ef7  : s2

                                                                                      ~   t             $,                                               _

4 D _ 3 T_ 2 omjm o ." 5t a M0'

7 Figure 12. Tube RIC38 '96 Data, Laboratory Analysis of + Point Coil U-Bend Indication

                                                                                                                       '                                                                                                          tn
                                                                                                   -t N>-         .u.

e2V e2V 2.61 e 2 300 Khz 31 [ ] SG P0l4 EOL El 34 x station-re REEL 514 SIDEhl h vrotation$ see S/G KEE I MLET h us. or stan t outs: se estamns risiscan: sisitesan3si 488 STD l +0.00 l:l IH

                                                                                                                                                     '#'"*                             EXTEHT                 TEH j TEH    INN SPEED                 0.09lin/see  TRAIN N -                 is     -

l TRIGGER l lttEASURE x,, A O t.n N s E E Ypp M 4'l HDD o

                                                                   !  !                          1                           L                                                                                                    c:
                                                                 -1    .l_     i    ;_ _

f ~ 4 d as c1 Spras ~4t - - S 4'D .j p= M:s: p A

                                                               =            -     ..

e a 1

                                                        -     _-                                                                                      w,                                                                          .

5 -

                                                                                                                                     -               pnxv                                                                         n c                                                 w                   'e             p                    ' ~

mM/ sr..... !2 I I kC

                                                        =
 -_ _ _ - - _ - _ - - _ _ - _ - - - _ _ - _ - - _ - _ _                                                                                       __ _           __ _           _ _    _    _ _____ _ _ _ _ __                      A}}