ML19312B772

Forwards Steam Generator Operating History in Response to NRC 771209 Request

ML19312B772
Person / Time
Site:	Oconee
Issue date:	02/16/1978
From:	Parker W DUKE POWER CO.
To:	Case E Office of Nuclear Reactor Regulation
References
NUDOCS 7911190562
Download: ML19312B772 (32)

Text

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,s REGULATORYINFOhdbTIONDISTRIBUTIONSYSTEM' IDS)

-DISTRIBUT10N FOR XNCOMINO MATERIAL ._io - 2 0 '70/287 4

EC: CASE E G ORG: PARKER W O DOCDATE: 02/16/_78-NRC DUKE PWR DATE RCVD: 02/_21/79 OCTYPE:' LETTEF NOTARIZED: NO COPIES RECEIVED

,UB. JECT: LTR 1 ENCL 1

' 5PON:E TO ?RC"S LTR DTD 12/09/77.

FURNISHING INFO CONCERNING TEAM GENERATCR OPERATING HISTORY.

_1NT NAME: OCONEE - UNIT 1 REVIEWER INITI AL: XJM OCONEE - UNIT 2 DISTRIBUTER INITI AL:

OCONEE - UNIT 3

• ++++"+++4++-***** OISTRIBUTION OF THIS MATERIAL IS AS FOLLOWS ******************

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M CUNNINCHAM - ALL AMENDMENTS TO FSAR AND CHANGES TO TECH ?PECS GENERAL DISTRIBUTION FOR AFTER ISSUANCE OF OPERATING LICENSE.

(DISTRIBUTION CODE AOO1)

• W/7 ENCL FOR ACTION: E R '-' .._.

INTERNAL: REG FILE ++t3/D - NRC PDR**W/ ENCL

. c ou 2. ENCL OELD**LTR ONLY HANAUER**W/ ENCL CHECK **W/ ENCL EISENHUT**W/ ENCL SHAO**W/ ENCL BAER**W/ ENCL BUTLER **W/ ENCL GRIMES **W/ ENCL J COLLINS **W/ENCI J. MCGOUGH**W/ ENCL EXTERNAL: LPDR'S WALHALLA, SC**W/ ENCL TIC ++W/ ENCL NSIC**W/ ENCL ACRS CAT B4*W/16 ENCL DISTRIBUTION: LTR 40_ ENCL 39 CONTROL NER: 7sO53OO10 SIZE: 1P+14P+17P

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DUKE POWER COMPANY Powsm Bt:sto No 4a2 SocTn Caracu STazzT. CitAHLOTTE. N. C. 28242 wiwau o. maa ca.sa. February 16,1978 s.cr p=cs.ocar *tttewowc: Aaca 704 src = paoovcoom f

, 73-4083 Mr. Edson G. Case, Acting Director , ,;~<- ~

Office of Nuclear Reactor Regulation } c-

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U. S. Nuclear Regulatory Commission Washington, D. C. 20555 3

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RE: Oconee Nuclear Station sj g Docket Nos. 50-269, -270, -287 An %-

Dear Sir:

In response to your letter of December 9, 1977 concerning steam generator operating history, please find attached the information requested with regard to the Oconee Nuclear Station.

Very truly yours, ,

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William O. Parker, Jr.

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9 8 AIfACHMENT 1 OCONEE NUCLEAR STATION UNIT 1 STEAM GENERATOR HISTORY l

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OCONEE NUCLEAR STATION ,

UNIT 1 1

1. BASIC PLANT INFORMATION Startup Date: July 15, 1973 Utility: Duke Pcwer Company Location: Seneca, South Carolina Thermal Power Level: 2568 MWt NSSS Supplier: Babcock and Wilcox (B & W)

Number of Loops: 2 Steam Generator Supplier, Model No., Type: B & W, 177 FA, Once Through Steam Generator (OTSG)

Number of tubes per Generator: 15,530 Tube Size, Material: Alloy 600; 0.625" OD; 0.557" ID If, STEAM GENERATOR OPERATING CONDITIONS Normal Operation Inlet Temperature: 602.8'F Primary Pressure: 2200 psi Secondary Pressure: 925 psi Allowed Leak Rate: 0.3 gpm 6

Primary Flow Rate: 65.66 x 10 lb/hr Accidents

. Design Basis LOCA; Maximwn Delta-P: 925 psi Main Steam Line Break; Maximum Delta-P: 2200 psi y - -

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III. STEAM GENERATOR SUPPORT PLATE INFORMATION j = '

Material: SA 212 B Carbon Steel Design Type: Broached 1

5 Design Code: AS)2 III (through 1967) i Dimensions: 58.7" R, thickness 1.5" 6

Steam Flow Rate: 5.3 x 10 lb/hr i

j Tube Dimensions: 5/8" D (nominal) .

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IV. STEAM GENERATOR BLOWDOWN INFORMATION Oconee Nuclear Station's Once Through Steam Generators (OTSG) are not designed to perform normal blowdowns. There is no operational requirement to perform normal blowdownc. The steam generator sample line, however, i can provide a limited blowdown capability of 1 GPM during power operation.

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V. WATER CHEMISTRY SPECIFICATIONS A. Feedwater (Normal Power Operation)

J 10 ppb (max)

Total Solids Cation Conductivity 0.5 pmho/cm (max) l Dissolved Oxygen as 02 7 ppb (max) i Hydrazine as N 2Hg 1-25 ppb Silica-as SiO2 20 ppb (max)

Total Iron as Fe 10 ppb (max)

Total Copper as Cu 2 ppb (max) pH @ 77'F 9.3-9.6 Lead as Pb 1 ppb (max)

Feedwater (Startup*)

Total Iron as Fe 100 ppb (max)

Cation Conductivity 1.0 pmho/cm (max)

Dissolved Oxygen as 02 100 ppb (max)

Hydrazine 300% of stoichiometric 02

• Established prior to f a.eding OTSGs.

B. OTSG Water (Less Than 102 Steaming) pH 9.0-10.5 Cation Conductivity 10 umh em (mar)

Chloride 1.4 Jt. ~ .* pt )

Sodium 2.0 ppm (max)

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OTSG Water (Layup) 4 Ammonia as NH3 10 ppm (nominal) 2 ppm-20 ppm range ph @ 77'F 9.5-10.5 Hydrazine 200 ppm initial 50 ppm (min)

Sodium 1.0 ppm (max)

Cation Conductivity 10 pmho/cm (max)

C. Condenser Cooling Water Condenser Cooling Water is obtained from Lake Keowee. There are no demineralizers or cooling towers installed. The following is a table of representative chemistry values:

Calcium 2.2 ppm Magnesium 0.7 ppm Sodium 1.7 ppm Potassium -0.9 ppm Bicarbonate Alkalinity 13.6 ppm Sulfates 1.1 ppm l

Chlorides 0.6 ppm Phosphates <0.2 ppm Nitrates 0.1 ppm Free Carbon Dioxide .11.0 ppm

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Silica 6.1 ppm Total Iron 0.05 ppm Manganese 0.12 ppm

_pH 6.5-7.0 kN i

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9 VI. TURBINE STOP VALVE TESTING Turbine Stop Valve Testing had been performed on a daily basis from initial startup until February 1974, when weekly testing was initiated.

In July 1975, the testing frequency was returned to a daily basis for stop valves and weekly for the control valves. In March 1977 when it appeared that stop valve testing might possibly contribute to steam generator tube failure, the frequency was citanged back to monthly.

Frequency Actual: Monthly (maximum time between tests is 6 weeks)

Recommended: Daily (turbine vendor)

Monthly (steam generator vendor)

Pcwer Level Actual: 65 percent full power, or 94 percent full power if power reduction not desirable Recommended: 65 percent full power (steam generator vendor)

No recommendation (turbine vendor)

Testing Procedures Actual: Stroke Length - full - 8.5 inches

- to trip - 8.0 inches Stroke Rate - open to closed - 13 sec.

- closed to open - 27 sec.

Recommended: same as actual

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VII. STEAM GENERATOR TUBE DEGRADATION HISTORY INSERVICE INSPECTION RESULTS November 1974 A.

Initial Refueling Inservice Inspection Steam Generator 1A:

umber of Tubes Inspected

573 (3.69%)

Number of tubes plugged: 0 Metalurgical Exam Results: No evidence of degradation in excess of 20%

Steam Generator 13:

Number of Tubes Inspected: 493 (3.171) 2 Number of Tubes plugged: 0 Metalurgical Exam Results: No evidence of degradation in excess of 20%.

B. March 1976 - 293 Effective Full Power Days (EFPD) since last refueling inspection r

Steam Generator lA Number of tubes inspected: 469 (3.02%)

Number of tubes plugged: 0 Metalurgical Exam Results: No evidence of degradation in excess of 20%

Steam Generator 1B Number of Tubes Inspected: 495 (3.19%)

Number of tubes plugged: 0 Metalurgical Exam Results: No evidence of degradation in.

excess of 20%

9-s C. August 1977 - 308 EFPD since last refueling inspection Steam Generator lA 4 4 Number of tubes inspected: 2500 (16.10%)

Number of tubes plugged prior to this ISI: 2 (.01%)

Number of tubes plugged this ISI: 5 (.03%)

Metalurgical Exam Results: All 5 tubes were in periphery region and exceeded degradation limits. All five tubes showed localized OD degradation with a maximum wall thinning of 60%. The defect area was at the 14th support plate. The tubes were 8-5, 117-107, 146-14, 147-11 and 7-4.

Steam Generator 1B Number of tubes inspected: 5004 (32.22%)

Number of tubes plugged prior to this ISI: 19 (0.1%)

Number of tubes plugged this ISI: 34 (0.22%)

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Metalurgical Exam Results:

'Al tubes were in the periphery region.

All tubes plugged showed localized OD degradation with a maximum wall thinning of almost 100%.

The defect area was at the 14th support plate except as noted:

88-122 (9th)64-125(1)99-125 138-68 68-127 37-4 100-124 51-123 75-121 (12th) 8-49 101-120 68-131(1)76-122 (12th)60-114 (12th) 101-122 43-108( }- 100-122 (13th)93-110 41-110 75-113 (14th) 62-11 16-71 9-51 (12th) 61-12 17-79 (13th) 8-48 7-32 (between 12th-13th)60-127 76-111 7-53 (11th)61-123 83-117 133-56 (11th)

(1)not plugged this ISI

( ) removed for further study Tubes 22-92, 133-57, and 79-2 were also plugged during this ISI for reasons other than exceedance of degradation limit.

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REGION IDENTIFICATION Region # Tubes Within Region

' Periphery of Bundle (1) 6806 (43.82%)

Tube Lane (2) 636 (4.09%)

Interior 8088 (52.08%)

Total 15,530 Allowed wall thinning before plugging = 40%

(1) Defined as tubes outside a 12 sided polygon connecting support rod positions (~20 rows)

(2) Within 5 rows of open tube lane i

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. A. October 31, 1976 R0-269/76-17 OTSG 1 A Number of tubes leaking 1 Number of additional tubes inspected 15 Total number plugged / removed 2 Summary a) Tube 77-17 plugged due to leakage b) Tube 77-18 also plugged B. December 8, 1976 R0-269/ 76-19 OTSG 1 B Number of tubes leaking 1 Number of additional tubes inspected 139 Number of tubes plugged / removed 4 Summary a) 114-109 plugged due to leakage at 14th support plate (SP) b) Tubes 113-110, 75-18, 113-115, also plugged C. January 15, 1977 R0-269/77-2 OTSG 1 B Number of tubes leaking 1 Number of tubes additional inspected 140 i

Number of tubes plugged / removed 2 Summary 4

a) Tube 75-12 plugged due to crack at upper support U

' plate b) . Tube 81-128 also plugged

. . . ) 9 D. February 28, 1977 R0-269/77-8 OTSG 1 B Number of tubes leaking 1 Number of additional tubes inspected ~3%

Number of tubes plugged / removed 6 Summary a) Tube 32-13 plugged due to leakage at 14th SP b) Tubes also plugged: 101-4, 33-14, 2-7, 77-25, 2-8.

c) Tube removed: 77-25 E. March 22, 1977 R0-269/77-17 OTSG 1 B Number of tubes leaking i Number of additional tubes inspected 100 Number of tubes plugged / removed 5 Summary a) Tube 77-25 identified as leaker (weld failure in old plug) b) Tubes also plugged: 77-3, 77-5, 77-8, 77-22, 77-29 F. May 7, 1977 R0-269/77-16 OTSG 1 B Number of tubes leaking 1 Number of additional tubes inspected 507 Number of tubes plugged / removed 3 Summary a) Tube 77-15 identified as leaker with crack 1/4" belou upper tube sheet b) Tube 17-5 also plugged c) Tube 75-18 removed

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-IX. CONDENSER INFORMATION As stated earlier in Section V of this report,-water from Lake Keowee is used to provide condenser cooling. Condenser tubes are made of 304 Stainless Steel. During operation, tube leakage is detected by secondary chemistry analysis for silica; a maximum of 20 ppb is allowed.

A search for a tube leak occurs whenever the silica concentration in the' secondary begins to increase.

Condensor tube leakage:

Date Remarks November 1974 2 tubes plugged

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X. RADIATION EXPOSURE WITH RESPECT TO STEAM GENERATORS Date Generator Dose (Exam & Repair) ( Comment:

11/74 A&B 44 First Refueling ISI 3/76 A&B 28.3 Second Refueling ISI 10/76 A 22 OTSG A leak 12/76 B 25 OTSG B leak 1/77 B 18.7 OTSG B leak 2/77 B 25.4 OTSG B leak 5/77 B 18 OTSG B leak 8/77 A&B 25.7 (exam) Third Refueling ISI 20.4 (repair)

Total A&B 391 (1) Dose in man-rem; testing and repair were not always separable.

XI. DEGRADATION GROWTH OTSG 1B Tube Number Location 2/76 1/77 5/77 9/77 90-124 14th S.P. -- --

20-30% 25-30%

113-112 14th S.P. -- --

30% 30%

81-128 14th S.P. 60%(l) 80% -- -- 98-128 14th S.P. -- --

0% 35%

No evidence of real degradation growth in tubes90-124 and 113-112.

Tube 81-128 was plugged 1/77 and tube 98-128 is still in service.

EFPD between 2/76 - 1/77 is approximately 179.

EFPD between 5/77 - 9/77 is approximately 63.

(1) Computer evaluation techniques not available at time but tube was backchecked when 80% indication was observed.

There are no tubes with a degradation history in Steam Generator lA.

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J A ATTACIO!ENT 2 OCONEE NUCLEAP. STATION UNIT 2 STEAM GENERATOR HISTORY

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.J OCONEE NUCLEAR STATION-UNIT 2

2. BASIC PLANT INFORMATION Startup Date: September 9, 1974 Utility: Duke Power Company Location: Seneca, South Carolina Thermal Power: 2568 MWt NSSS Supplier: Babcock and Wilcox (B & W)

Number of Loops: 2 Steam Generator Supplier, Model No. , Type: B&W, 177 FA, Once Through Steam Generator (OTSG)

Number of tubes per Generator: 15,530 Tube Size, Material: Alloy 600; 0.625" OD; 0.557" ID II. STEAM GENERATOR OPERATING CONDITIONS Normal Operation Inlet Temperature: 602.8*F 6

Primary Flow Rate: 65.66 x 10 lb/hr Primary Pressure: 2200 psi Secondary Pressure: 925 psi Allowed Leak Rate: 1 gpm Accidents Design Basis LOCA; Maximum Delta-P: 925 psi Main Steam Line Break; Maximum Delta-P: 2200 psi

III. STEAM GENERATOR SUPPORT PLATE INFORMATION Material: SA 212 B Carbon Steel Design Type: Broached Design Code: ASME III (thru 1967)

Dimensions: 58.7"R, thickness 1.5" 6

Steam Flow Rate: 5.? x 10 lb/hr Tube Hole Dimensions: 5/8" D (nominal)

IV. STEAM GENERATOR BLOWDOWN INFORMATION Oconee Nuclear Station's Once Through Steam Generators (OTSG) are not designed to perform normal blowdowns. There is no operational requirement to perform normal blowdowns. The steam generator sample line, however, can provide a limited blowdown capability of 1 GPM during power operation.

V. WATER CHEMISTRY SPECIFICATIONS

• Water chemistry specifications for Unit 2 are the same as Unit 1, and are contained in Attachment 1,Section V.

VI. TURBINE STOP VALVE TESTING Turbine stop valve testing procedures for Unit 2 are the same as those for Unit 1 and are contained in Attachment 1,Section VI.

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. VII. STEAM GENERATOR DEGRADATION HISTORY INSERVICE INSPECTION RESULTS A. April 1976 - Initial Refueling Inspection Steam Generator 2A Number of tubes inspected: 479 (3.08%)

Number of tubes plugged prior to this ISI: 0 Number of tubes plugged this ISI: 0 Metalurgical Exam Results: No evidence of degradation in excess of 20%

Steam Generator 2B Number of tubes inspected: 476 (3.07%)

Number of tubes plugged prior to this ISI: 0 Number of tubes plugged this ISI: 0 Metalurgical Exam Results: No evidence of degradation in excess of 20%

B. August 1977 - 277 EFPD since last refmaling inspection Steam Generator 2A Number of tubes inspected: 506 (3.26%)

Number of tubes plugged prior to this ISI: 0 Number of tubes plugged this ISI: 0 Metalurgical Exam Results: No evidence of degradation in 1

excess of 20% l Steam Generator 2B Number of tubes inspected: 987 (6.36%)

i Number of tubes plugged prior to this ISI: 3 (.02%)

Number of tubes plugr,ed this ISI: 4 (.03%)

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- o Metalurgical Exam Results: Three tubes plugged were in-the lane region and one in the interior. Maximum degrada-tion was in excess of 40%. All were degraded at the 15th SP except the interior tube, which ras at the 12th SP.

The plugged tubes were: 75-5 uane 75-9 Lane 78-2 Lane 112-29 Interior REGION IDENTIFICATION Region # Tubes with Region Periphery of Bundle (1) 6806 (43.82%)

Tube Lane (2) 636 (4.09%)

Interior 8088 (52.08%)

Total 15,530 Allowed wall thinning before plugging = 40%

i (1) Define as tubes outside a 12 sided polygon connecting support rod positions ('20 rows) l (2) Within 5 rows of open tube lane.

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VIII. ABNORMAL OPERATIONAL EVENTS

. December 4, 1976 R0-270/76-15 OTSG 23 Number of tubes leaking 1 Number of additional tubes inspected 133 Number of tubes plugged / removed 3 Summag a) Tube 77-23 plugged due to leakage at upper tube sheet b) Tubes also plugged: 77-27, 124-42

, c) Tubes removed: 77-27, 77-23 IX. CONDENSER INFORMATION As stated earlier in Section V of this report, water from Lake Keowee is used to provide condenser cooling. Condenser tubes are made of

304 Stainless Steel. During operation, tube leakage is detected by secondary chemistry analysis for silica; a maximum of 20 ppb is allowed. A search for a tube leak occurs whenever the silica concen-tration in the secondary begins to increase.

Condenser tube leakage:

Date Remarks January 1975 2 tubes plugged i

X. RADIATION EXPOSURE WITH RESPECT TO STEAM GENERATORS Date Generator Dose (Exam & Repair)( Comments 4/76 A&B 2.1 First Refueling ISI 12/76 B 25 OTSG B leak

j. 8/77 A&B 13.5 (exam) Second Refueling ISI 36.5 (repair) SOAK Instrumentation insertion 1 (2) and OTSG repair 1/78 B 11 OTSG B leak and SOAK removal 10/77 B 18 (exam) OTSG B leak Total A&B 106.1 (1) Dose in man-rem; examination and repair dosages could not always be separated.

l (2) SOAK (Second-Of-A-Kind) Flow-vibration instrumentation added for 1

additional information on possible causes of OTSG leakage.

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i XI. DEGRADATION GROWTH OTSG 2B Tube Number Location 12/76 6/77 75-5 15th S.P. 60% 85%

i 75-9 15th S.P. 40% 60%

75-14 15th S.P. 20% 20%

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EFPD between 12/76 - 6/77 is approximately 180.

i Tube 75-5 has since been stabilized, tube 75-9 has been removed and 4

1 tube 75-14 is still in service.

There are no tubes with a degradation history in Steam Generator 2A.

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e ATTACHMENT 3 OCONEE NUCLEAR STATION LTIT 3 STEAM GENERATOR HISTORY l

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O D OCONEE NUCLEAR STATION UNIT 3 I. BASIC PLANT INFORMATION

-Startup Date: December 10, 1974 Utility: Duke Power Company Location: Seneca, South Carolina Thermal Power: 2568 MWt NSSS Supplier: Babcock & Wilcox (B & W)

Number of Loops: 2 Steam Generator Supplier, Model No. Type: B & W, 177 FA, Once Through Steam Generator Number of tubes per Generator: 15,530 Tube Size, Material: Alloy 600; 0.625" OD; 0.557" ID II. STEAM GENERATOR OPERATING CONDITIONS Normal Operation Inlet Temperature: 604*F 6

Primary Flow Rate: 65.66 x 10 lb/hr Primary Pressure: 2200 psi Secondary Pressure: 925 psi Allowed Leak Rate: 1 gpm Accidents Design Basis LOCA; Maximum Delta-P: 925 psi Main Steam Line Break; Maximum Delta-P: 2200 psi

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III. STEAM GENERATOR SUPPORT PLATE INFORMATION

. . Material: SA 212 B Carbon Steel

. Design Type: Broached Design Code: ASME III (thru 1967)

Dimensions: 58.7"R, thickness 1.5" 6

Steam Flow Rate: 5.6 x 10 lb/hr Tube Hole Dimensions: 5/8" D (nominal)

IV. STEAM GENERATOR BLOWDOWN INFORMATION Oconee Nuclear Station's Once Through Steam Generators (OTSG) are not designed to perform normal blowdowns. There is no operational requirement to perform normal blowdowns. The steam generator sample line, however, can provide a limited blowdown capability of 1 GPM during power operation.

V. WATER CHEMISTRY SPECIFICATIONS Water chemistry specifications for Unit 3 are the same as Unit 1 and are contained in Attachment 1,Section V.

VI. TURBINE STOP VALVE TESTING PROCEDURES Turbine Stop Valve Testing Procedures for Unit 3 are the same as those for Unit 1 and are contained in Attachment 1,Section VI.

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VII. STEAM GENERATOR DEGRADATION HISTORY A. November 1976 - Initial Refueling Inspection Steam Generator 3A Number of tubes inspected: 586 (3.77%)

Number of tubes plugged prior to this ISI: 0 Number of tubes plugged this ISI: 0 Metalurgical Exam Results: No evidence of degradation in excess of 20%.

Steam Generator 3B Number of tubes inspected: 489 (3.15%)

Number of tubes plugged prior to this ISI: 3 (0.02%)

Number of tubes plugged this ISI: 0 Metalurgical Exam Results: 4 tubes had degradation between 20-30%. No other tubes showed evidence of degradation in excess of 20%

B. October 1977 - 289 EFPD since last refueling inspection Steam Generator 3A Number of tubes inspected: 1090 (7.00%)

Number of tub 2s plugged prior to this ISI: 0 Number of tubes plugges this ISI: 0 Metalurgical Exam Results: No evidence of degradation in excess of 20%

Steam Generator 3B Number tubes inspected: 1090 (7.00%)

Number of tubes plugged prior.to this ISI: 20 (0.13%)

Number of tubes plugged this ISI: 0 Metalurgical Exam Results: 6 lane tubes had evidence of degradation between 20%-40% at the 15th SP but' were not plugged.

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. REGION IDENTIFICATION Region # Tubes With Region

Periphery of Bundle (1) 6806 (43.82%)

Tube Lane (2) 636 (4.09%)

interior 8088 (52.08%)

Total 15,530 Allowed wall thinning before plugging 40%

(1) Defined as tubes outside a 12 sided polygon connecting support rod positions (~20 rows)

(2) Within 5 rows of open tube lane i

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l VIII. ABNORMAL OPERATIONAL EVENTS A. July 21, 1976 R0-287/76-10 OTSG 3B Number of tubes leaking 1 Number of other tubes inspected not available Number of tubes plugged / removed 3 Summary a) Tube 77-11 was plugged due to leakage about 10 feet below tube sheet.

b) Tubes 81-63, 37-6 were also plugged.

B. February 14, 1977 R0-287/77-2 OTSG 3B Number of tubes leaking 1 Number of other tubes inspected 142 Number of tubes plugged / removed 11 Summary a) Tube 77-19 was plugged due to leakage from crack at 15th SP b) Tubes 75-2 and 77-12 thru -21 were also plugged.

C. June 10, 1977 R0-287/77-8 OTSG 3B Number of tubes leaking 1 Number of other tubes inspected 133 Number of tubes plugged / removed 1 Summary a) Tube 78-1 was plugged due to leakage at 15th SP b) Leak rate was approximately doubled by mainsteam stop value test conducted while leak was monitored

I D. - ' July 14, 1977 R0-287/77-10 OTSG 3B Number of tubes leaking 1 Number of other tubes inspected 120 Number of tubes plugged / removed 2 Summary a) Tube 77-2 was plugged due to leakage at bottom of upper tube sheet b) Tube 77-1 was also plugged 1X. CONDENSER INFORMATION As stated earlier in Section V of this report, water from Lake Keowee is used to provide condenser cooling. Condenser tubes are made of 304 Stainless Steel. During operation, tube leakage is detected by secondary chemistry at.alysis for silica; a maximum of 20 ppb is allowed. A search for a tube leak occurs whenever the silica concen-tration in the secondary begins to increase.

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Condenser tube leakage:

, ,, , Date Remarks August 1976 Two tubes plugged october 1976 Identified cause of previou leakage as a broken bypass line support member causing steam to impinge directly on condenser tubes. Plugged approximately 150 tubes that were bent February 1977 One tube plugged April 1977 One tube plugged May 1977 Three tubes plugged December 1977 One tube plugged i

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