ML17321B011

Summary of 851204 Meeting W/Util & Westinghouse Re Steam Generator Tube Leaks,Repairs & Exam as Result of Jul & Aug 1985 Outages.List of Attendees & Viewgraphs Encl

ML17321B011
Person / Time
Site:	Cook
Issue date:	12/18/1985
From:	Wigginton D Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8601020520
Download: ML17321B011 (31)

Text

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Docket, No.:

50-316 LICENSEE:

FACILITY:

SUBJECT:

Indiana and Michigan Electric Company (IMEC)

Donald C.

Cook Nuclear Plant, Unit No.'2 Summary of Meeting Held on December 4, 1985 with Indiana and Michigan Electric Company to Discuss Steam Generator Tube Leaks The staff met with the licensee and their representatives from Mestinghouse to discuss the steam generator tube leaks, repairs and examination as a re-sult of the July and August 1985 outages.

The list of attendees is attached as Enclosure l.

The licensee's presentation was made from the viewgraphs attached as Enclosure 2;

some proprietary.viewgraphs have been withheld from disclosure.

The Unit 2 Model 51 steam generators have been in service for about 5 effective full power years.

All row one tubes have been plugged.

Some anti-vibration.bar problems has occurred typical for these steam generators.

In November 1983, the first crevice corrosion indications occurred.

Following this, a program was begun to improve secondary side chemistry and to replace condenser tubes as sources of contaminants.

As a result of the July-August 1985 outage due to tube leaks, a full examination was performed for all the tubes in Unit 2.

In 1984, 7 tubes were pulled with indication of integranular attack and stress corrosion cracking.

There was one indication at a support plate.

In 1985, 5

tubes were pulled as representative of a number of problems in the crevice area, above the tube sheet, and at the hot leg side support plates.

The support plate problems are new in the U.S. but have also been found in plants in Japan.

The chemistry and destructive exam strongly suggest the tubes at the support plates are subjected to a caustic environment.

From the information available, the licensee has justified the three months operations until the refueling outage and is expected to submit a report in the near future on the completed examinations.

Additional tests will be per-formed at the refueling outage and a

new report submitted subsequent to restart to justify operation beyond three months, assuming the condition at startup is equivalent to the current analysis.

The licensee has taken positive steps to reduce the corrosion problems in-cluding independent eddy - current tests review, leak rate monitoring program, secondary side chemistry control (retube main condenser with 304SS and tighten 8b01020520 851218 PDR ADOCK 0500031b

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$S85 specs on impurities), cutting down on air leakage, crevice flushing, operation with boric acid inhibitors, and sludge lancing.

During the refueling outage beginning in March 1986, the licensee will replace the feedwater boilers, ex-amine the tubes according to the technical specification requirements, and perform normal steam generator work.

The licensee is also examining sleeving, T hot reduction, and steam generator replacement for the long term.

/s/

Enclosure:

As stated cc:

See next page Dave Wigginton, Project Manager PWR Project Directorate ¹4 Division of PWR Licensing-A PWR¹ DPWR-A PWR¹4/DPWR-A DWigginton/mac QBJYoungblood 12/[ $ /85 12/ (9 /85

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Mr. Jdhn Dolan Indiana and Michigan Electric Company Donald C.

Cook Nucl ear Plant CC:

Mr. M. P. Alexich Vice President

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Nuclear Operations American Electric Power Service Corporation-I Rivers.ide Plaza

Columbus, Ohi o 43215 Attorney General Department of Attorney General

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525 West Ottawa Street Lansing, Michigan 48913

'ownship Supervisor Lake Township Hall Post Office Box 818

Bridgman, Michigan 49106 W. G. Smith, Jr., Plant Manager Donald C.

Cook Nuclear Plant Post Office Box 458 Bridgman, Michigan '9106 U.S. Nuclear Regulatory Commission Resident Inspectors Office 7700 Red Arrow Highway Stevensvi Ile, Michigan 49127 Gerald Charnoff, Esquire Shaw, Pittman, Potts and Trowbridge 1800 M Street, N.W.

Washington, DC 20036 Mayor, City of Bridgeman Post Office Box 366 Bridgman, Michigan 49106 Special Assistant to the Governor Room I - State Capitol Lansing, Michigan 48909 Nuclear Facilities and Environmental Monitoring Section Office Division of Radiological Health Department of Public Health 3500 N..Logan Street Post Office Box 30035 Lansing, Michigan 48909 The Honorable John E. Grotberg United States House of Representatives Washington, DC 20515 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 J. Feinstein American Electric Power Service Corporation I Riverside Plaza

Columbus, Ohio 43216

ENCLOSURE I S.

G.

TUBE LEAK MEETING DECEYiBER 4, 1985 NANE D. Wigginton B. Turovlin H. F. Conrad C. Y. Cheng T. Sullivan

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C.

D. Sellers G. Johnson L. Connor J. Feinstein D.

R. Mafer J.

Kobyra H.

Fouad V. VaudenBurg J. Wojcik G. Whiteman

,A.

W. Klein, D. D. Malinowski Ken Huffman ORGANIZATION NRC-NRR NRC-NRR NRC-NRR NRC-DPLB-EB NRC-PWR-A-EB NRC-PWR-A-EB NRC-PWR-A-EB Doc-Search Associates AEPSC AEPSC AEPSC AEPSC AEPSC AEPSC/D.

C.

Cook Westinghouse-NTD-NS Westinghouse-SGTD Westinghouse-SGTD Westinghouse-NDE Center

DEMISTERS SECONDARY MOiSTURE SEPARATOR ENCLOSURE 2

STEAM OU TO TOR8INE GENERATOR ORIFICE RINGS SECONDARY MANY/AY SWIRL VANE PRIMARY MOISTURE SEPARATOR FEEDWATER INLET'PPER SHELL FEEDWATER RING ANTIVIBRATIONBARS l.NOZZLES TUBE BUNDLE WRAPPER LOWER SHELL TUSE SUPPORT PIATES BLOWDOWN UNE TUBE SHEET SECONDARY HANDHOLE PRIMARY MANWAY PRIMARY COOLANT INLET TUBE LANE BLOCK PRIMARY COOLANT OUTLET Q~

SERIES 51 STEAM GENERATOR NOT TO SCALE 9916

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EDDY CURRENT SIGNAL CLASSIFICATION "CLEAR I.NDI CATION" r

A SIGNAL MITH UNEQUIVOCAL PHASE ANGLE NEASURABt E AT 400 KHz, CONFIRNED AT 100 KHz, >~1 VOLT.

EiGep R7C58 HL ¹1 TSP R18C77 HL ¹5 TSP DISTORTED INDICATION

.A SIGNAL VISIBLE.AT 000 KHz BELIEVED TO REPRESENT TUBE

. DEGRADATI'ON BUT MITH UNQUANTIFIABLE PHASE ANGLE;.SUP-PORTED BY 100.KHz ABSOLUTE, EaGop R18C77 HL ¹1 AND ¹2 TSPs A

"SQUIRREL".

A SIGNAL MHOSE TRACE AT 000 KHz IS COMPLEX AND PHASE ANGLE UNCLEAR, BUT MHOSE PRESENCE REPRESENTS CHANGE:

CORRELATED MITH TUBE DEGRADATION IN PRIOR EXPERIENCE; SUPPORTED BY 100 KHz ABSOLUTE DRIFT SHIFT IN 100 KHz/QOOKHz ABSOLUTE MIX Y-AXIS (+) X-AXIS (-)

TRACES SUGGESTIVE OF TUBE DEGRADATION MHILE 000 KHz DIFFERENTIAL TRACE IS QUIET, EoGop

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8. 4 1 VOLTS 1c.9,s w

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'&1 VOLT PEAK TO PEAK 400 KHZ - DIFFERENTIAL

1. 60 VOLTS 137 s

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CHAHHEL IN 4 100 KHZ - ABSOLUTE FIGURE 4 CIIrWHEL I~a 4 Ig OD INDICATION t 83 VOLTS 81 OEG 8:.

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ItDIII FIGURE 6 100 KHZ - ABSOLUTE FIGURE 8 CHAHHEL HO 4 OD INDICATION 2.87 VOLTS 54 DEG

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" 22 COLO 88r31r85

~ t l 1/85 18 16 CRACK DEPTH DISTRIBUTION I

NEAN APPROX. >/2 MAX.

I HEAN 12 FREQUENCY OF OCCURRENCE A16C77-1 l1ICRO 0981

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3 5

7 9

11 13 15 17 19.

2 l CAACItl DEPTH, fllLS

EDDY CURRENT MEASUREMENT ERROR METAL OGRAPHY SHOWED IMPROVING AGREEMENT WITH EC ESTIMATE WITH INCREASED DEPTH OF PENETRATION, FOR SECTIONS WITH REAL SCC DEPTHS IN EXCESS OF 40X THE EC ESTIMATES YIELD AN AVERAGE OF 16X UNDER-PREDICTION.

THIS'ESULT IS NOT UNEXPECTED, AS DETECTION OF SCC BY BOBBIN PROBE EC TESTING IN FIELD APPLICATIONS HAS INDICATED LOW SENSITIVITY BELOW 40X TUBEWALL PENETRATION,

COOl< 2 DEGRADATION RATES CALCULATIONS INDICATE THAT PROGRESSION RATE VARIES MITH ELEVATION IN THE STEN GENERATOR.

TUBES HEET CREVICE ABOVE TUBESHEET SUPPORT PLATES OVERALL AVERAGE DEGRADATION RATE FOR'LL THREE ZONES IS APPROXINATELY 10.0X OVER 10.5 I'19NTHS EQUIVALENT FULL PO'4'ER OPERATION..

k FOR THE CONTENPLATED OPERATING INTERVAL - APPROXIMATELY 90 DAYS APPLICATION OF THE HIGHEST REGIONAL DECRADATION RATE (28K OVER 10.5 EFPI IN THE TUBESHEET CREVICE) IS CONSISTENT WITH THE REQUIRED hlNINUf'l MALL THICKNESS.

COOK 2 DEGRADATION RATE CALCULATIONS.

IDENTIFICATION OF EC INDICATIONS AS RESULTING FROM STRESS CORROSION CRACKING POSES CHALLENGE TO GROWTH RATE DETERNI NATION',

o TYPICALLY SCC 4 40% IS NOT DETECTED AND SCC ~40%

HAS BEEN PLUGGED.

o RATE DETERNINATION COULD REDUCE TO AVERAGING OBSERVED INDICATIONS BUT UNDETECTABLE CRACKS NOST LIKELY EXISTED.

IN ORDER TQ CHARACTERIZE THE SITUATION WITH QUANTITATIVE INDICES, SEVERAL AVENUES MERE EXPLORED:

1.

RE-ANALYZE 1984 RESULTS FOR TUBES WITH CLEAR SIGNALS IN 1985;,SELECT NOST WELL-BEHAVED DATA AND CALCULATE CHANGES.

2 FORCE DEPTH ESTIMATES ON ALL INDICATIONS (DI's IiN 1985 AND BEST ESTINATE OF UNREPORTED 1984 DATA);

CALCULATE CHANGE, 3.

ADJUST EC DEPTH ESTINATES BASED ON TUBE PULL NETAL-LOGRAPHY; CALCULATE CHANGE.

s', 'i MINIMUM TUBE WALL REQUIREMENTS IN ACCORDANCE WITH THE CRITERIA OF RG 1. 121 DC COOK UNIT 2 STEAM GENERATORS STRUCTURAL LIMIT FOR NORMAL PLANT OPERATION~

PRIMARY TUSE STRESSES ARE LIMITED SUCH THAT A MARGIN'F 3 IS PROVIDED AGAINST EXCEEDING THE ULTIMATE TENSILE STRESS OF THE TUBE MATERIAL I

THE YIELD STRENGTH OF THE TUBE MATERIAL IS NOT EXCEEDED DURING NORMAL OPERATION FOR POSTULATED ACCIDENT CONDITIONS~

THE REQUIREMENTS OF SECTION NB-3225 OF SECTION II I OF THE ASME CODE APPLY FOR ALL DESIGN TRANSIENTS'HE, CUMULATIVE FATIGUE USAGE FACTOR MUST BE LESS THAN UNITY EAK BEFORE BREAK DEMONSTRATION THROUGH WALL CRACKS WITH A SPECIFIED LEAKAGE LIMIT DURING NORMAL OPERATION DO NOT PROPOGATE AND RESULT IN TUBE RUPTURE DURING POSTULATED ACCIDENT CONDITION LOADINGS

D.

C.

COOK NUCLEAR PLANT UNIT 2 OPERATING INTERVAL JUSTIFICATION CATEGORY ALLO/'!ABLE z ECT. UNCERTAINTY 16 16 16 CREVICE ABOVE TS TSP 62 62 70 GROWTH PLUGGING LEVEL REQUIREt) (R)

PLUGGING LEVEL INPLB'lENTED (X)

ALL 0%

50 8,0"

'40 NARGIN AFTER 5 l'iONTHS OPERATION (i')

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" WORST CASE GROWTH RATE PROJECTED FOR 5 EFPN OPERATION

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3. fretting at Tube Lane Blocking Devices.

16 - Row 1 ECT indications 520 - Row. 1 nreventative Olugging 0 - Defects at AVB Mtersections R Defects at tubesheet

surface, hot leg

"-"'::- ""'-".M--'-'Fiidic'aotkins':at'fubesheet" surhice"'".%bet--.%en--.". < " 1 ~: 5 - Defects at tubesheet

surface, cold leg 59 - Befects in crevice region, hot leg 01 - Indications in crevice region,.hot leg 0 - Defects at 1st suooort nlate intersections, cold leo 16 Defects at suPPort nlate.intersections.

col/ lea 6 - fk)n-defective tubes remyed for tube analsisis 8 - Niscel laneous (Preservice, mistakes,.etc.) ~ t g ~ 612 - TOTAL \\ ~ ~ ~ ~ ~ 0 MEETING

SUMMARY

DISTRIBUTION QEQ 1 8 198S Docket File NRC PDR L PDR NSIC PRC System PWR84 Reading File Project Manager Dave Wi inton M. Duncan

Attorney, OELD J. Partlow E. Jordan B. Grimes ACRS (10)

NRC Partici ants D. Wigginton B. Turovlin H. Conrad C.

Cheng T. Sullivan C. Sellers G. Johnson OTHERS bcc:

Licensee 5 Service List

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