ML17058A832

Summary of 910619 Meeting W/Util Re Upcoming mid-cycle Insp & Possible Repair of HPCS Nozzle at Facility.List of Meeting Attendees & Viewgraphs Encl

ML17058A832
Person / Time
Site:	Nine Mile Point
Issue date:	06/27/1991
From:	Brinkman D Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9107050046
Download: ML17058A832 (80)

Text

Docket No. 50-410

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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 20555 June 27, 1990 LICENSEE:

FACILITY:

SUBJECT:

Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station, Unit 2 MEETING MINUTES REGARDING THE JUNE 19, 1991, MEETING TO DISCUSS THE UPCOMIVG MID-CYCLE INSPECTION AND POSSIBLE REPAIR OF THE HPCS NOZZLE AT NINE MILE POINT 2.

A meeting was held in the NRC One White Flint North Office in Rockville, Maryland, with Niagara Mohawk Power Corporation (NMPC) and NRC staff representatives to discuss the planned inspections, fracture mechanics

analysis, and possible repairs of the HPCS nozzle at Nine Mile Point 2 during the upcoming mid-cycle inspection.

Enclosure 1 is a list of the meeting attendees.

The handout material used by the licensee during the meeting is attached as Enclosure 2.

By letter dated December 28, 1990, NMPC submitted for NRC staff review and approval a fracture mechanics evaluation of a flaw that had been detected in the weld (KC-32) joining the HPCS nozzle safe end to the safe end extension.

The flaw had been'etected by a scheduled ultrasonic inservice inspection during the plant's first refueling outage.

After subjecting the weld to a

Mechanical Stress Improvement Process, the licensee determined the flaw to be 41% of wall thickness and to extend 11.3% of the wall circumference.

The NRC staff reviewed the licensee's submittal and requested the licensee commit to performing a mid-cycle inspection of the subject weld.

By letter dated January 7, 1991, the licensee committed to perform the requested mid-cycle inspection between the beginning of the fifth and end of the tenth month of the second refueling cycle.

The NRC staff's safety evaluation of the licensee's analysis concluded that the Nine Mile Point 2 reactor pressure vessel was acceptable for service without excavation and weld repair of the flaw in weld KC-32 provided the flaw would be ultrasonically reexamined during the committed mid-cycle inspection.

The NRC staff's safety evaluation also recommended that the licensee submit for staff review and approval, a revised fracture mechanics analysis performed in accordance with recommendations contained in the safety evaluation.

A further recommendation was to consider using radiographic examination techniques for examination of weld KC-32 during the mid-cycle inspection.

The licensee requested this meeting to update the NRC staff on the status of the revised analysis and to inform the staff that attempts to perform radiographic examination of weld KC-32 did not produce radiographs of acceptable quality and therefore this technique will not be used during the kRC,,IRK CREES mSpK 9s07050046 910627 PDR ADOCK 050004i0 PDR

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mid-cycle inspection.

During the meeting, the licensee committed to submit a revised fracture mechanics analysis by June 28, 1991.

The NRC staff agreed to promptly review this revised analysis as well as the proposed repair plan submitted on June 10, 1991.

It was agreed that if any significant growth (to be defined by NMPC and agreed to by the NRC staff) of this flaw is detected during the mid-cycle inspection, further evaluation will be required as well as a probable repair.

However, if the NRC staff determines the revised analysis to be submitted on June 28, 1991, is acceptable and there is no significant growth of the flaw, the plant may resume and continue operation without repairing the weld (KC-32) until the next refueling outage when the weld will be reinspected.

Enclosures:

1. List of Attendees

2. Licensee Handout Material Donald S. Brinkman, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc w/enclosures:

See next page

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Nr. B. Ralph Sylvia Niagara Mohawk Power Corporation Nine Nile Point Nuclear Station Unit 2 CC:

Nr. Nark J. Wetterhahn, Esquire Winston

& Strawn 1400 L Street, HW.

Washington, D.C. 20005-3502 ter. Richard Goldsmith Syr acuse University College of Law E. I. White Hall Campus

Syracuse, Hew York 12223 Resident Inspector Nine Nile Point Nuclear Power Station P. 0.

Box 126

Lycoming, New York 13093 Nr. Gary D. Wilson, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202 Nr. David K. Greene Manager Licensing Niagara mohawk Power Corporation 301 Plainfield Road

Syracuse, New York 13212 Ms.

Donna Ross New York State Energy Office 2 Empire State Plaza 16th Floor

Albany, Hew York 12223 Supervisor Town of Scriba R.

D.

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Oswego, New York 13126 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 Charlie Donaldson, Esquire Assistant Attorney General New York Department of Law 120 Broadway New York, Hew York 10271 Hr. Richard N. Kessel Chair and Executive Director State Consumer Protection Board 99 Washington Avenue

Albany, New York 12210 Nr. Hartin J.

HcCormick Jr.

Plant Manager, Unit 2 Nine Nile Point Nuclear Station Niagara tiohawk Power Corporation P. 0.

Box 32

Lycoming, NY 13093 Nr. Joseph F. Firlit Yice President

- Nuclear Generation Nine Nile Point Nuclear Station Niagara Mohawk Corporation P,. 0.

Box 32

Lycoming, New York 13093

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ENCLOSURE 1

ATTENDANCE LIST June 19, 1991 Meeting With Niagara Mohawk Power Corporation to Discuss Upcoming Mid-cycle Inspection and Possible Repair of HPCS Nozzle at Nine Mile Point 2

Name Donald S.

Brinkman Robert A. Capra C. Y. Cheng W. David Baker John Tsao Richard B. Abbott W. A. Koo Tom Fay M. Banic John Swenszkowski Christopher A. Boen H. Kaplan Robert Hermann W. S. Fingrutd Sam Ranganath Carl Terry Martin J. McCormick, Jr.

Shashi Dhar Robert Deuvall Daniele Qudinot Position Senior Project Manager Project Director Chief, Mat and Chem Eng. Br.

Licensing-Program Director Materials Engineer NMPC Mgr. Unit 2 Eng.

Materials Engineer NMPC - Licensing Materials Engineer NMPC - (jA/NDE Group Lead Materials Co-op Reactor Inspector Chief, Met Sect GE - Sr. 1felding Spec.

Manager, Mat, Mon & Stru Anal VP - Nuclear Engineering Plant Manager NMP2 Mech Engineer NMP2 Supervisor Mech Eng NMP2 Project Engineer Or anization NRC/NRR/PD I-1 NRC/NRR/PD I-1 NRR/DET/EMCB Niagara Mohawk NRR/DET/EMCB NMPC NRR/DET/EMCB NMPC NRR/DET/EMCB NMPC NRC/Rgn I NRC/Rgn I NRC/NRR/DET GE GE-NE NMPC NMPC NMPC NMPC NRC/NRR/PDI-1

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ENCLOSURE 2 NIAGARAMOHAWKPOWER CORPORAl ION HPCS CORE SPRAY NOZZLE MEETING AGENDA JUNE 19, 1991 PEAKERS INTRODUCTION/PURPOSE R. ABBOTT BACKGROUND INFORMATION S. DHAR FRACTURE MECHANICS ANALYSIS M. BADLANI (SMC O'DONNELL, INC.)

IV.

UNCERTAINTYIN FLAW SIZING UTILIZINGUT TECHNIQUES J. SWENSZKOWSKI V.

UTILIZATIONOF RT TECHNIQUE FOR EXAMINATIONPURPOSES J. SWENSZKOWSKI Vl.

CONTINGENCY REPAIR PLAN S. RANGANATH (GENERAL ELECTRIC)

Vll.

SUMMARY

R. ABBOTl

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BACKGROUND INFORMATION OF HPCS NOZZLE KC-32 FLAW IN-SERVICE INSPECTION OF HIGH PRESSURE CORE SPRAY NOZZLE SAFE END TO SAFE END EXTENSION WELD KC-32 PERFORMED IN OCTOBER 1990 REVEALED A FLAW THAT EXCEEDED THE ASME CODE ACCEPTANCE STANDARDS.

(B)

SINCE THE FLAWHAD PROPAGATED TO ALLOY182, WHICH IS SUSCEPTIBLE TO IGSCC, NMPC ELECTED TO UTILIZE MECHANICALSTRESS IMPROVEMENT (MSIP) AS A MEANS OF MITIGATING CRACK GROWTH DUE TO IGSCC BY IMPROVING THE RESIDUAL STRESS DISTRIBUTION AROUND THE TIP OF THE FLAW.

(C)

POST

MSIP, THE WELD WAS RE-INSPECTED.

THE RE-INSPECTION INDICATEDTHAT THE FLAW DEPTH WAS 0.36 INCHES (41 'Yo OF WALL THICKNESS) AND 3.4 INCHES (11.3/o OF CIRCUMFERENCE) IN LENGTH.

(D)

NMPC PERFORMED A FRACTURE MECHANICS ANALYSISTO SUPPLEMENT MSIP. THE FRACTURE MECHANICS ANALYSIS DISREGARDED BENEFIT OF MSIP.

THE THROUGH WALL RESIDUAL WELD STRESS DISTRIBUTION REPORTED IN NUREG-0313, REVISION 2, WAS UTILIZEDWHICH SHOWED THE FLAW TO GROW FROM A DEPTH OF 41% TO A DEPTH OF 69%

IN ONE FUEL CYCLE OF OPERATION (12,000 HOURS).

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(E)

NRC SAFETY EVALUATION OF FRACTURE MECHANICS ANALYSIS FOR KC-32 REQUIRED NMPC TO:

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PERFORM A MID-CYCLEINSPECTION OF NOZZLE WELD KC-32 (BETWEEN THE 5TH AND 10TH MONTH OF THIS CYCLE).

~

RESUBMIT FRACTURE MECHANICS ANALYSIS BASED ON MID-CYCLEINSPECTION WHICH WOULD:

(i)

ASSESS WELD RESIDUAL STRESSES IN 10" DIAMETER PIPE.

lh (ii)

ADDRESS UNCERTAINTY IN

'FLAW SIZING RESULTING FROM ULTRASONIC EXAMINATION.

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LOCATION OF FLAW LD I

I Flow WP SAP.E END EXTENSlON (SA-508 CL.1)

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NIAGARA i'lOHAWK POWER CORPORATION NINE NILE POINT UNIT 2 CRACK GROWTH EVALUATION FOR CORE SPRAY SAFE-END-TO-EXTENSION WELDNENT PRESENTED TO UNITED STATES NUCLEAR REGULATORY CoivIMISSION JUNE 1991

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GEOMETRY Bc MATERIALS RNITE ELEMENT MODEL QUALIFY MODEL WITH NUREG 0313/1061 WfLDING RESIDUAL STRESSES AT WELD MIDPLANE OPERATING LOADS STRESS DISTRIBUTION AT CRACK LOCATION STRESS INTENSllY FACTOR g CRACK GROW11I MSIP OPERATING LOADS STRESS DISTRIBUTION AT CRACK LOCATION CRACK DEPTH EXCEEDS COMPRESSIVE REGION CRACK DEP1H CRACK ARRESTED ANALYSIS FLOW CHART

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49.75 3 7.3 6.063

'ETAlL A 2.203 2.766 l.

DETu,::L a 00 5.047

~ ao 3 IL0.75 DE:i"'L rs CORE SPRAY NOZZLE GEOMETRY

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CRACK, TlP AIRWAYS

DEC, 10

) '99 44:5S:82 Pt OT NO.

PA'"-,T1

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ITEP, 2QQ i've.~

~ GLOBAL ONX 8.848 SNH

-3778 SNX 37211

. ME,LO CENTEH ZV DIST 1.78"-

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-2938 earn>

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3915 1 223>>

2856";

2888'

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Ut> laod fn (89) f 1~'JIIf 3.7 ioST HSIP AttlRI STIIY'SFS Ir( Tttt Shirr.-fno-IO-rrTCt stoa Iirln (0,7RA.': COIIT.'IACT10tt}

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MELO CBTER AHSYS DEC 18 a4:49:

PLOT No Pn':!T1

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lER Iei 5'>'A' GLQBAI OtN 8.

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DIST 1.'XFS.

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2 1 38.

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55i 18" Hozz le (H16) w. Extn. -Hew 0 8~

FlGVRE 3.ll POST NS1P AXlAL STRESSES MlTH OPERATlNG LOADS lRCLVDEO FOB THE SAFE-FNO-TO-FXTENStON XELO (u.788>. COillnACT<OWj

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ZHS10E'4U 50 40 o GE26 a GE'26 (4 ozimulhsI

< AHL 26(2 ozimuths)

< AHL 26 (N-SBtYlC= FROM KRH)

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0.2 THROUGH-MALL OISTRISUTION OF AXIAL RES IOUAL STRESS FROH HUREG-0313

INSlOK 'HALL 50 OUT SIOE SALL QQ 30 20 10 Ql Ul 0

-)0 0.2 Qg

,alt 0.8 ASSUMED THROUGH-MALL MELDING RESIDUAL STRESS DISTRIBUTION IN SHALL-0INETER MELDNENTS

(<Iz in.).

(FROM NUREG-1061)

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O'Donnel. l L Associates, Inc ~

Pitt,sburgh~

Pennsg lvania COPlBINED AXIAL STRESS (AS-IJELDED + NORPlAL OP

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Dou Pl 8 2 e.~

8 6 e 8 DISTANCE FRON THE I D ~

(LIALL FRACTION) e o

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COMBINED AXIAL STRESS DISTRIBUTION AT OPERATING CONDITIONS

STRESS INTENSITY FACTOR Stress Profile represented by third degree polynomial cro

~ Ao + A)X + A~X

+ A3X Stress Intensity Factor

[

Reference:

Dedhia and Harris, PVP Vol. 95, 1983]

K, j~a

[A F

+ aA,F,

+ a'A,F,

+ a'A,F,]

A, A A, and A, coefficients of the polynliial expression representing 0'he stress profile K (x) in the uncracked section a

crack depth, and F

, F F, and F, Influence function factors Oa

re' I

ioS 4.86 b

a 5

1.8 B.S F1.

>>rr reer r

~ rrree F2 eeerrree

+rrerere e~ orr re>>~ e~ e er e~ e F3 e.e e.z 8.3 e.s (ArT)

INFLUENCE FUNCTIONS FOR POWER STRESSES e.v

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0 'Donne I. l. L Assoclatea Inc i Pit tabula"gh Penna@ l.van ia STRESS INTENSITV FACTOR VS CRACK DEPTH 8 ~ 888 8+888 e.wee 8 688 CRACK DEPTH (QALL FRACTION) 8 880 STRESS INTENSITY FACTOR VERSUS CRACK DEPTH FOR OPERATING CONDITIONS INCLUDING AS-WELDED STRESS

il

pper K 'Plateau' N iO jn/hr.

15 20 25 4J 59 M

70 80%)N K Oai i~el CSL~OSiTc, CVCX GROWLS RP 4TIOiVSRIP VSB IH THE PIALUATIOil

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CRACK GROWTH ASSESSMENT MONTH ENDING TINE phrs CRACK DEPTH

/ Wall CRACK LENGTH*

/ Circumference Hay 91 June 91 July 91 August 91 Sept 91 Oct 91 Nov 91 Feb 92 0

2920 3650 4380 5110 5840 6570 7300 9700 41.18 46.59 47.85 49.08 50.27 51.43 52.55 53.63 56.95 11.2 12.7 13.0 13.3 13.7 14.0 14.3 14.6 15.5 Threshold K1 28.5 ksiJin Plateau Growth Rate 5.0 x 10 in/hr.

• Assuming length grows in same ratio as depth.

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O'Danne ll L Assaciates Inc.

Pit tsburgh Pennsg Lvania is 8'8 8'5 r

r 8.48 4888 6888 TIP1E

( HRS )

CRACK DEPTH AS A FUNCTION OF OPERATING TINE

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8 18 O'Donnelly L Associates, Ines Pi M sbua"gh>

Pennsg t..mania 8.i6 8'4 8 iB 8+18 4888 6888 TIPlE

( HRS )

CRACK LENGTH AS A FUNCTION Of OPERATING TINE

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O'Donnell h Associates, Inca Pitt sburgh Pannsg lvanla 1.5 Eeergonc 8 Faulto F

3 B Norma l 8 Upse g Uithout PlSIPi Crack Stable aft ar 97BB Hrs g Last Out age UT Resu lt s Crack Stable ASIDE Section XI IUB 3618 Limits 0 B e.w 8 6 8 ~ 8 NON-9IPlENSIONAL CRACK LENGTH (LiPI4D) i 0 FAILURE ANALYSIS DIAGRAH

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CONCLUSIONS

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ANALYSIS BASED ON THf ACTUAL POST-MSIP DISTRIBUTION CORRESPONDING TO FIELD MEASURED PIPE CONTRACTION INDICATES THAT THE CRACK RfMAINS IN THE COMPRESSIVE REGION.

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FOR THE HYPOTHETICAL CASE WITHOUT MSIP, FRACTURE MECHANICS EVALUATION BASED ON A CONSERVATIVE LINEAR AS-WELDED RESIDUAL STRESS, PREDICTS A

CRACK DEPTH LESS THAN 57/o OF THE WALL THICKNESS AFTER ONE FUEL CYCLE.

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PREDICTED CRACK DEPTH AFTER ONE CYCLE MEETS THf ASME CODE SECTION XI LIMIT AND THE CRACK REMAINS IN THE STABLf REGIME.

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ANALYSIS RESULTS RECONFIRM THAT SAFE OPERATION CAN BE CONTINUED THROUGH THE CURRENT CYCLf.

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UT UNCERTAINTY PAGE10F 3 o

U.T. EXAMINATIONSWERE PERFOM4ED TO ASMX SECTION XI CODE, WITH ENHANCEMENTS ENDORSED BY THE EPRI NDE CENTER.

o EPRI REQUIRES THATTHE TECHNIQUES EIVIPLOYED (PROCEDUIRE, EQUIPMIENT, A1VD PERSONNEL) BE QUALIFIEDBY DEMONSTRATION, ON SAMPLES WITH DEFECTS OF KNOWN QVAI'A'ITIESAl'Gl QUALITIES.

ALLUT EXA3dEVATIONSPERFOID'IED ON THIS WELD WERE BY PROCEDURE, EQUIPIVIENT, AND PERSOI%NEL THAT EIA&BEEN QUALIFIEDAT THE EPRI NDE CEN'rER.

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o AUTOMATEDUT EXAMINATION IDENTIFIEDTHE PH)ICATION.

o FOUR (4) DIFFERENT ALUT TECKVIQUES WERE UTILIZEDTO SIZE TEE INDICATION. TEE RESULTS %ERE ALLCONSISTENT KITHEACH OTHER A2'6) SUPPORTED THE AUTOMATED EXAM.

o AI<TER A MODIFICATIONON AN ADDITIONALARIMOF Tj.'IIS:SYSTEM BOTH AUTOMATEDAlVD ALUT E

ATIONS WERE REPERFOM4ED.

THE RESULTS WERE ALSO CONSISTENT WHH Tl&'REVIOUSLYPERFORMED SIZING.

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UT UNCERTAINTY PAGE 3 OF 3 o

UT UNCERTAPtTY SHOULD NOT BE A FACTOR AS TIXE TECKNIQUES THAT WERE EMPLOYED AIRE STATE OF THE ART A1%3 HAVE BEEN PROVEN BY DEMONSTRATIONTO ACCUIDTELY MEASURE THE SIZES OF KNOWN DEFECTS.

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FEA'SISIIITYOF RADIOGRAPHY ON

':"::, ".'" HPCS::,INDICATION:";,':;:,"-'",:

o A WATER FILLEDMOCK-UP OF THE NOZZLE WAS RADIOGRAPHED IN THE SHOP USING APPROXIMATELYA 70 CURIE IR 192 SOURCE.

o RESULTS PtDICATED THATBY USING A STRONGER SOURCE MEAMNGFUL RESULTS COULD POSSIBLY BE OBTAINED.

o A 200. CUME SOURCE OF IR 192 WAS OBTAPKD AZG) RADIOGRAPHYWAS ATTEMPTED ON THE AIBACONTAIINlNG THE Il%3ICATION.

o RESULTS OF TIIE RADIOGRAPHS WERE INCONCLUSD'E (RADIOGRA'HS %'ERE NOT OF READABLEQUALITY).

o ADDITIONALRADIOGIRABHS WERE ATTEMPTED USING DIFFERENT SPEED FILMS AND WITH VARYINGTHE SOURCE ANGLE.

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FEASIBILITYOF RADIOGRAPHY ON

,:. HPCS INDICATION:::,::.;;:;:;,::-:,::;..

";-",';-"":""'-'.':::;PAGE 2 OF 2 0

THESE ALSO DID NOT PRODUCE RADIOGRAPHS OF ACCEPTABLE QUALITY.

o TO PURSUE Fib'%TED RADIOGRAPHY ON THIS WELD WOULD RESULT IN UNNECESSARY EXPOSUI& TO PERSOINM< L AM)NOT YjKLD A2'A'lEMlING&JL P8'OKNATION.

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WELD OYERLAY DESIGN BASIS FOR NlNE MILE POlNT 2 CORE SPRAY NOZZLE SAFE END TO SAFE END EXTENSION WELD PRKSKNTED SY SAM RANQANATH GK NUCLEAR KNERGY SAN JOSEi CALXFORNXA

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THXCKNKSS SASKO ON XWS-3640 ANO Ap~aNOXX C az SECTXON XZ CONSXDERS PRESSUREi WEXGHT AND SEXSMXC ZNERTXA LOADXNG NO CREDXT TAKKN FOR RENAXNXNG PIPE CROSS-SECTION>>

7HVS XNDKPKNDENT OF CRACK SXZK 0

MXNXMUM LKNGTH XS

~RT L.KNGTH GENERALLY GREATER FOR UT XNSPKCTASXL.XTY SHRZ NKAGE ANALYSIS ASSURES STRESSES KLSEl4HERK 1N THE PXPXNG SYSTEM ARE L4XTHXN ALLOMASI.K VALVES SYSTEM MELDS MITH INDICATIONS NEED TO SE RKEVALUATEO

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Pipe Cross Se tions Stress Oistributions At Net Section Collapse Pm Pm+Pl c Neutral Axis Section A-A (Uncracked Section) 0

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Section B;B (Cracked Section)

~ 0 Figure 2 - Weld Overlay Stress Distributions at Net-Section Collapse R50-0591. QP 12

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THICKNESS DESIGN FOR A

FULL STRUCTURAL OVERLAY l

r/2 R>>

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Neutral axis 6S a

p'b 2 sin p 7r p, =sap. + p,) p.

WELD OVERLAV THICKNESS = ( ~

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- Weld Overlay Thickness Calculation Summary

• • 0 0 a 0 **0 0 0 *0 0 0 0 0 *1 I1*0 0 *%**%1 1'* 0 %*%*0 *0 I*1 0*0 0 0 1 *0 0 **0 0 *1 0 0 0 0 0 0 0 0 0 0 0 PLANT ID!

NINE MILE POINT 2

WELD ID:

SAFE END TO SAFE END EXT PIPE THICKNESS ~

0'8 INCH PIPE DIAMETER

~ 11. 38 INCH PRIMARY STRESSES:

PRESSURE DEAD WEIGHT MEMBRANE DEAD WEIGHT BENDING SEISMIC MEMBRANE SEISMIC BENDING SM WELD MATERIAL SM PIPE MATERIAL 3.66 KSI 0.27 KSI 2.98 KSI 0.58 KSI 4'3 KSI 23'0 KSZ

~ 23. 30 KSI WOT T+WOT PB (KSZ)

PM+PB PM+PB/3 PM (KSZ)

REMOTE WOT (REMOTE)

(WOT) 0.255 0.774 3.595 5.333 23.556 8.928 9.050 PRIMARY STRESSES!

PM PM+PB 3.595 M 8.928 5lIMUM REQUIRED WELD OVERLAY THICKNESS ~ 0'55 INCH MINIMUMREQUIRED WELD OVERLAY WIDTH

~

2.2 INCH

• • 00 04*0 0 O*O****1*0*******0*

0 1***t 0 01 4*01****OOOOOO*1% 0 1 0 1 0 1*11*4*1*1 R50-0591. WP 13

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0.26" hain Overlay Tl>ickiiess Excludirig First l.ayer 2.75" Min x

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Flow First Layer of Overla Wg SAF.E END EXTENSION SAFE ENl)

After filial fiiiisliiiigllic t<il> siirface of tlie overlay, tlie i>veri;iy slioulil illtei'sec t tile silfe elld sill'filce Wltll a i>>axiiiiuiiiof 1/n-i>>i;il iiiiilerfill ol'ocal excess reii>fc>n ciiieiit aiid willi a I/O" iiii>>. r'>diiis.

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CNAtVPLF OF

~lQ< < WC.~& CvEX4AAV l~ E XA~~ AFAR AE.ZuaZaa WiO VL.i CC= OvCuc &V

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THE F ULL STRU CTURAt. MELD OVERLAY FOR THE Nh4P 2

CORE SPRAY NOZZLE. SAFE END TO SAFE END EXTENSXON MEL.Dt MEETS ALt.

CODE, NRC AND UT XNSPECTASX I.XTY CRZTKRXA

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MMARY NMPC A TI N

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SUBMIT REVISED FRACTURE MECHANICS ANALYSISTO NRC BY

'JUNE 28 FOR APPROVAL

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PERFORM MID-CYCLE UT INSPECTION OF WELD KC-32

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EVALUATE UT RESULTS WITH RESPECT TO THE RESULTS OF REVISED FRACTURE MECHANICS ANALYSIS.

THE FOLLOWING CRITERIA WILL BE UTILIZED:

(i)

IF FLAW LENGTH AND DEPTH FOR THE PERIOD OF EVALUATION IS WITHIN ALLOWABLE LIMITS AS ESTABLISHED BY THE ANALYSIS, NO FURTHER ACTION WILL BE TAKEN UNTILTHE REFUELING OUTAGE.

(ii)

IF FLAW LENGTH FOR THE PERIOD OF EVALUATION EXCEEDS ALLOWABLE LIMITS AS ESTABLISHED BY THE ANALYSIS BUT DEPTH REMAINS WITHIN THE LIMITS ESTABLISHED, A

REVISED FRACTURE MECHANICS ANALYSISWILL BE SUBMITTEDTO NRC FOR ACCEPTANCE PRIOR TO STARTUP.

(iii)

IF FLAWDEPTH FOR THE PERIOD OF EVALUATIONEXCEEDS ALLOWABLELIMITS AS ESTABLISHED BY THE ANALYSIS, NMPC SHALL PERFORM REPAIR OF THE KC-32 WELD.

~

REVIEW AND APPROVE REVISED FRACTURE MECHANICS ANALYSIS

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APPROVE ASME XI REPAIR PLAN SUBMITTED ON JUNE 10, 1991

peg e I F ~

mid-cycle inspection.

During the meeting, the licensee committed to submit a revised fracture mechanics analysis by June 28, 1991.

The NRC staff agreed to promptly review this revised analysis as well as the proposed repair plan submitted on June 10, 1991.

It was agreed that if any significant growth (to be defined by NMPC and agreed to by the NRC staff) of this flaw is detected during the mid-cycle inspection, further evaluation will be required as well as a probable repair.

However, if the NRC staff determines the revised analysis to be submitted on June 28, 1991, is acceptable and there is no significant growth of the flaw, the plant may resume and continue operation without repairing the weld (KC-32) until the next refueling outage when the weld will be reinspected.

Original Signed By:

Enclosures:

1. List of Attendees

2. Licensee Handout Material Donald S. Brinkman, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc w/enclosures:

See next page DISTRIBUTION:

FMiraglia JCalvo PDI-1 Reading DBrinkman OGC NRC Participants CCowgill NRC Im Local PDRs JPartlow SVarga RACapra CVogan EJordan ACRS (10)

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CVogan DATE: Q/g,'Ij'91

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