ML20127P532

Summary of 850502 Meeting W/Util & Westinghouse in Bethesda,Md Re Steam Generator Tube Plugging for Indications within Tubesheet Region.List of Attendees & Viewgraphs Encl

ML20127P532
Person / Time
Site:	McGuire, Mcguire
Issue date:	05/09/1985
From:	Hood D Office of Nuclear Reactor Regulation
To:	Adensam E Office of Nuclear Reactor Regulation
References
TAC-61775, TAC-61776, NUDOCS 8505240017
Download: ML20127P532 (24)

Text

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.f - -y npa atog'h, . UNITED STATES 'e y7 g NUCLEAR REGULATORY COMMISSION

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May 9,.1985 T^DocketsNos:s .501369 -

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' MEMORANDUM FOR: Elinor G. Adensam, Chief Licensing Branch No. 4 Division of Licensing -

FROM: Darl S. Hood, Project Manager Licensing Branch No. 4 Division of Licensing

SUMMARY

OF MAY 2, 1985 MEETING ON STEAM GENERATOR TUBE PLUGGING FOR INDICATIONS WITHIN THE TUBESHEET REGION -

MCGUIRE NUCLEAR STATION On May 2,1985, the NRC staff met in Bethesda, Maryland with Duke Power Company and Westinghouse to address the issue of repairing or removing (plugging) a steam generator tuoe frcm service for the McGuire Nuclear Station if degradation were to be detected in the full depth hardroll expanded portion of the tube (within the tubesheet). Duke's purpose of the meeting was to discuss and seek NRC concurrence for a plugging criterion complementary to Regulatory Guide 1.121, but which recognizes the reinforcing effect of the tubesheet on the outside diameter of the tube. Meeting attendees are listed in Enclosure 1.

-Enclosure 2 is the handouts used during the presentations. It includes the text of Westinghouse's evaluation and development of a distance (designated P*) below the top of the tubesheet beyond which tube degradation of any extent wculd not result in a severed tube end becoming clear of the tubesheet during normal or postulated accident condit4cns. For degradation at or below such a location, Westirghouse finds that the integrity of the bundle would not be lost, nor leakage increased in excess of that for which the safety consecuences have been appropriately addressed. On the basis of Westinghouse's evaluation, Duke proposes that tubes with eddy current indications located 1.282 inches or more below the top of the tubesheet be left in service regard-less of the depth of the indication. Peripheral tubes and interior tubes adjaC8:nt' to and on the tubelane side of the tube support plate stayrods would be excluded.

Although cracking has not been observed to date at McGuire, Duke noted that primary plants e.g. (water stress Alamarez andcorrosion cracking Summer) with MA Alloyhas600 been observed tubes that were mechnically at some other nuc roll expanded into the tubesheet. The cracks are generally short and axial and occur at the expanoed/ron expanded transitions and at skip roll locations within the tubesheet. Duke proposed that the NRC review the abnve p'ugging criterion by June 1,1985, in order that it may be applied when the eddy current test results for McGuire Unit I will be available.

8505240017 850509 DR ADOCK0500g9 L

The staff noted its preference that the review of the proposed criterion and the general cracking phenomenon be performed on a generic basis, such as with an affected PWR Owners Group. The staff stated that, even if reviewed on a plant-specific basis, the technical review for the P* criterion could not be completed by June 1, 1985. The staff suggested, however, that if indications are found in the Unit 1 tubes within the tube sheet region, Duke should meet promptly again with the staff with the benefit of these data to review their significance in terms of the McGuire Technical Specifications.

et.

Darl S. Hood, Project Manager Licensing Branch No. 4 Division of Licensing

Enclosures:

As stated cc: See next page DESIGip5EDORI Certified BY 9

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McGuire Mr.'R. B. Tucker, Vice President Nuclear Production Department Duke Power Company 422 South Church Street

-Charlotte, North Carolina 28242 cc: Mr. A. Carr Duke Power Company

. P. O. Box 33189 422 South Church Street Charlotte, North Carolina 28242 Mr. F. J. Twogood Power Systems Division Westinghouse Electric Corp.

P. O. Box 355 Pittsburgh, Pennsylvania 15230 .

Mr. Robert Gill Duke Power Ccmoany Nuclear Production Deoartment P.--0. Box 33189 Charlotte, . North Carolina 28242

'J. Michael McGarry, III, Esq.

Bishop, Liberman~, Cook, Purcell and Reynolds-1200 Seventeenth Street, N.W.

Washington, D. C. 20036 Mr. Wm.~ Orders Senior Resident inspector c/o U.S. Nuclear Regulatory Commission Route'4, Box 529 Hunterville, North Carolina 28078 J. Nelson Grace, Regional Administrator U.S. Nuclear Regulatory Commission, Region II-101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323 R. S. Howard Operating Plants Projects Regional Manager Westinghouse Electric Corporation - R&D 701 P . 0. r!.. 1728 Pittsburgh, Pennsylvania 15230 w

Enclosure 1 MCGUIRE SG Tube Plugging May 2, 1985 Name Organization Darl S. Hood - LB4/DL/NRR B. D. Liaw MTEB/DE/NRR C. Y. Cheng MTEB/NRR G. W. Whiteman W - Nuclear Safety R. F. Keating W - SGTD C. McCracken - CMEB/DE/NRR B. Turovlin MTEB/DE/NRR C. W. Hendrix, Jr. DPC0/ Maintenance Engr.

-B. T. Estes, Jr. SCE&G - Nuclear Engr.

A. Monroe SCE&G - Nuclear Lic.

A. L. Sudduth Duke Power - Design Engr.

R. L. Gill Duke Power - McGuire Licen.

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hd.Y 5/z/J.T McGUIRE UNITS 1 AND 2 TUBESHEET PLUGGLNG CRITERION PRESENTATION OVERVIEh' 0 . INTRODUCTION . (A.L. SUDDiflH, DUKE P0hB)

V 0' 'IUBESHEET PLUGGING CRITERION DEVELOPMENT ( G.W. hEITSLAN, R.F. KEATING,.

WESTI.NGHOUSE) .

O PNSCC BACKGROUND CONSIDERATIONS (A.L.~ 'SUDDlTTH)-

0 DUKE P0hB"S PROPOSED ACTIONS (A.L. . SUDDlmi)

- 0' " REQUESTED NRC ACTIONS (R.L. GILL, DUKE P0hB)-

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. . i TUBE PLUGGING CRITERION IN THE 1UBESHEET REGION

.I TE0fiICAL SPECIFICATION PLUGGING LIMIT APPLIES 15 00GH

- EE 1UBE LENGlE

- ACCCU.NT FOR THE CONSTRAINING EFFECT OF THE TUBESHEET i DEFLNE A REGION WITHIN THE TUBESHEET IN hEICH NO PLUGGING REQUIRBENTS NEED APPLY l-r

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Tubesheet Plugging Criteria Tubesheet y y i '

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4 PULLOW CRITERIm (P*) DEVELOPMENT BRIEP OVERVIEW EASPECTS O TUBE BURST WILL NOT OCCUR WIEIN EE EBESHEET 0 1UBE COLLAPSE WILL NOT OCCUR WIEIN E E TUBESHEET 0 TEONICAL SPECIPICATION LEAKAGE LDiITS APPLY CCNSIDERATIONS 0 A PIXED OR CAPIURED TUBE END IS MAISTAINED 0 PRDIARY-TO-SECONDARY LEAKAGE IS LDiITED 0 - TUBE IhTEGRITY IS MAIhTALNED UNDER LD1ITING CONDITIONS 0 IUBE IhTEGRITY ABOVE P* IS DEMONSTRATED ( BY CONTINUED ECT)

'O ECT AXIAL UNCERTAIhTY

- -- RESULTS 0 TUBE PULLOUT IS PRECLUDED 0 1UBES WIE INDICATIONS BELOW P* REMAIN LN SERVICE O P* CRITERION DGuS NOT APPLY TO PERIPHERAL 1UBES AND SWE IhTERIOR TUBES

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6 WBESHEET REGION PRIMARY WATER STRESS CORROSION CRACKING BACKGROUND CONSIDERATICNS PRIMARY WATER SCC HAS BEEN OBSERVED IN MA ALLOY 600 WBES WHICH WERE MEOiANICALLY ROLL EXPANDED INTO EE WBESHEET

-0 CRACISABE GENERALLY SHORT AND AXIAL: NO REPORTS OF CIRCINFERENTIAL CRACKING LN DGESTIC PL\ HTS

O CRACKING OCCURS AT EXPANDED /NON EXPANDED TRANSITIONS AND AT SKIP ROLL LOCATIONS WIEIN EE WEESHEET s

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DUKE PGER'S PROPOSED ACTIONS FOR FtGUIRE UNITS 1 AND 2 0 LlNG METALLURGY WILL BE REVIEhTD TO ASSESS SUSCEPTIBILITY TO F6 SCC O- MANUFACWRING DATA AND BASELINE EDDY CURRENT DATA WILL BE REVIEh'ED FOR LOCATION OF SIGNIFICANT WBE GEGIEIRY DEVIATIONS IN IFi TUBESHEET REGION:

ROLL TRANSITIONS

-- ROLL STEPS OVERLAP BEThEEN ROLL STEPS 0 INSPECTIONS OF THE TUBESHEET REGION WITH CONTENTIONAL BOBBIN PROBES WILL BE AUGIENTED WITH RPC OR 8 X 1 PROBES O PERMANEhT CORRECTIVE ACTIONS ARE BEING PURSUED IN RESEARCH PROGRAMS SPONSORED BY THE STEAM GENERATOR OhhERS GROUPf AND BY hESTINGHOUSE l

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% J REQUESTED hE ACTIONS

'O ' NRC CONCURRENCE WITH TECHNICAL JUSTIFICATION OF 1UBESHEET PLUGGING CRITERICN

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Ifew/fJq-sfit u INTRODUCTION PURPOSE-TO ADDRESS THE ISSUE OF REPAIRING OR REMOVING A STEAM GENERATOR TUBE FROM SERVICE WHEN THE DEGRADATION HAS BEEN DETECTED IN THE FULL DEPTH HARDROLL EXPANDED PORTION OF THE TUBE (WITHIN THE TUBESHEET).

A PPR O A CH ESTABLISHMENT OF A CRITERION COMPLEMENTARY TO USNRC REGULATORY GUIDE 1.121 BASED ON CONSIDERATION OF THE REINFORCING EFFECT OF THE TUBESHEET ON THE OUTSIDE DIAMETER OF THE TUBE.-

CONCLUSION THE NEED TO REPAIR OR REMbVE A TUBE FROM SERVICE IN THE DUKE MCGUIRE NUCLEAR POWER PLANTS IS OBVIATED WHEN THE GOVERNING EDDY CURRENT INDICATIONS ARE WITHIN A SPECIFIED PORTION OF THE TUBESHEET.

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. ~ APPLICABLE CRITERI A USNRC REGULATORY GUIDE 1.121 ~

REGULATORY GUIDE 1.121 DESCRIBES AN ACCEPTABLE METHOD FOR ESTABLISHING THE LIMITS FOR TUBE DEGRADATION, BEYOND WHICH -

- TUBES ARE TO BE REPAIRED OR REMOVED FROM SERVICE. THE

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ACCEPTABLE DEGRADATION IS REFERRED TO AS THE TUBE PLUGGING LIMIT. -

THE PURPOSE IN COMPLYING WITH THE REQUIREMENTS OF RG 1.12I IS TO PRECLUDE THE SAFETY CONSEQUENCES WHICH MIGHT BE ASSOCIATED

.WITH THE RUPTURE OF A NUMBER OF SINGLE TUBE WALL BARRIERS.

" RUPTURE IS DEFINED AS ANY PERFORATION OF THE TUBE PRESSURE BOUNDARY ACCOMPANIED BY A FLOW OF FLUID EITHER FROM THE PRIMARY TO THE SECONDARY SIDE OF THE TUBE OR VICE VERSA, DEPENDING ON THE DIFFERENTIAL PRESSURE CONDITION PREVAILING

. DURING NORMAL-PLANT OPERATION OR DEVELOPED IN THE EVENT OF POSTULATED PIPE BREAK ACCIDENTS WITHIN EITHER THE PRIMARY REACTOR COOLANT PRESSURE BOUNDARY OR THE STEAM SYSTEM PRESSURE BOUNDARY.*

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USNRC RG 1.121 B ASIC REOUIREMENTS THE BASIC REQUIREhENTS CONSIST OF THE FOLLOWING:

I. STRUCTURAL LIMITS - *

1. NORMAL PLANT OPERATION - PRIMARY TUBE STRESSES ARE LIh0TED SUCH THAT A MARGIN OF 3 IS PROVIDED AGAINST EXCEEDING THE ULTIMATE TENSILE STRENGTH OF THE TUBE MATERIAL, AND THE YIELD STRENGTH OF THE TUBE MATERIAL IS NOT EXCEEDED.

2. ACCIDENT CONDITIONS - THE REQUIREhENTS OF PARAGRAPH NB-3225 OF SECTION III OF THE ASME CODE ARE TO BE MET, AND APPLIED LOADS ARE LESS THAN THE BURST STRENGTH OF THE TUBES AS DETERMINED BY TEST.

3. FATIGUE - THE CUMULATIVE USAGE FACTOR MUST BE LESS THAN UNITY ACCOUNTING FOR ALL DESIGN TRANSIENTS.

II. LEAK BEFORE BREAK DEMONSTRATION -

THROUGH WALL CRACKS WITH A SPECIFIED LEAKAGE LIMIT DURING NORMAL OPERATION DO NOT PROPAGATE AND RESULT IN TUBE RUPTURE DURING POSTULATED ACCIDENT CONDITIONS.

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TREATMENT OF'TUBESHEET TUBE INDICATIONS PREMISE THE BASIC PREMISE TO BE APPLIED IS THAT IF A SEVERED TUBE END IS

,CONSTRAIMED SUCH THAT IT CANNOT BECOME CLEAR OF THE TUBESHEET ,

THE INTEGRITY OF'THE BUNDLE IS CONSERVED, AND IF LEAKAGE IS LIMITED THE SAFETY CONSEQUENCES OF LEAKAGE HAVE BEEN APPROPRIATELY ADDRESSED.

APPLICATION OF RG 1.121 IDENTIFICATION OF A DISTANCE, DESIGNATED P*, BELOW THE TOP OF THE TUBESHEET FOR WHICH TUBE DEGRADATION OF ANY EXTENT WILL NOT RESULT IN A SEVERED TUBE END FROM BECOMING CLEAR OF THE TUDESHEET DURING NORMAL OR POSTULATED ACCIDENT CONDITIONS.

CONSIDERATIONS

1. DEVELOPMENT OF THE ENGAGEMENT D;5TANCE REQUIRED TO MAINTAIN A FIXED TUBE END CONDITION IN THE TUBESHEET WITH A POSTULATED CIRCUMFERENTIAL INDICATION.

2. LIMITATION OF PRIMARY-TO-SECONDARY LEAKAGE CONSISTENT WITH ACCIDENT ANALYSIS ASSUMPTIONS.

3. MAINTENANCE OF TUBE INTEGRITY UNDER POSTULATED LIMITING CONDITIONS OF PRIMARY TO SECONDARY AND SECONDARY TO PRIMARY DIFFERENTIAL PRESSURE.

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TUBESHEET EFFECTS RELATIVE TO THE PERFORMANCE OF DEGR ADED TUBES

' BURST STRENGTH OF FULL DEPTH EXPANDED TUBES THE BURST STRENGTH OF THAT PORTION OF A TUBE LOCATED WITHIN THE TUBESHEET IS REINFORCED TO THE EXTENT THAT THE PRESENCE OF THE TUBE MATERIAL IS NOT NECESSARY, I.E., TUBE BURST IS OBVIATED BECAUSE DEFORMATION BEYOND THE EXPANDED OUTER DIAMETER IS ESSENTIALLY PRECLUDED.

• COLLAPSE STRENGTH OF FULL DEPTH EXPANDED TUBES THE COLLAPSE STRENGTH OF THAT PORTION OF THE TUBE LOCATED WITHIN THE TUBESHEET IS SIGNIFICANTLY INCREASED. COLLAPSE MODES WHICH ARE ACCOMPANIED BY LOCAL DEFORMATION BEYOND THE OUTER DIAMETER-(GEOMETRICAL REACTION) ARE SIGNIFICANTLY STRENGTHENED.

• LEAKAGE OF FULL DEPTH EXPANDED TUBES

, NO ACTUAL LEAKPATH IS EXPECTED DUE THE HARDROLLING OF THE TUBES INTO THE TUBESHEET. LEAK RATE EFFECTS HAVE BEEN ASSESSED BY ASSUMING A LEAK PATH TO EXIST AND DETERMINING THE RELATIVE LEAKAGE %HICH WOULD OCCUR DURING POSTULATED ACCIDENT CONDITIONS.

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- DEVELOPMENT OF THE P* CRITERION DEVELOPMENT OF THE P* CRITERION IS BASE ON ASSUMING THAT A TUBE HAS BEEN DEGRADED TO THE POINT OF SEVERENCE WITHIN THE TUBESHEET. THE SEVERED TUBE IS POSTULATED TO MOVE UPWARD TO A POSITION WHERE,THE EXTRADOS SURFACE OF THE U-BEND APEX IS IN CONTACT WITH THE TUBE DIRECTLY ABOVE IT. UNDER OPERATING OR ACCIDENT CONDITIONS ADDITIONAL DISPLACEMENT MAY OCCUR. THE TOTAL ' AMOUNT OF UPWARD MOVEMENT HAS BEEN ADDRESSED BY THE FOLLOWING CONSIDERATIONS.

• MANUFACTURING CONSIDERATIONS ,

A STUDY OF THE FABRICATION AND ASSEMBLY PROCESS WAS CONDUCTED.WHICH INCLUDED CONSIDERATION OF NOMINAL GAP DIMENSIONS AND MANUFACTURING STEPS WHICH COULD RESULT IN VARIATIONS TO THE NOMINAL DIMENSIONS. A MAXIMUM AS-BUILT GAP VALUE WAS IDENTIFIED.

• THERMAL EXPANSION CONSIDERATIONS VERTICAL DISPLACEMENT OF A SEPARATED TUBE U-BEND WAS CONSIDERED TO BE THAT OF AN INTACT OUTBOARD NEIGHBOR TUBE U BEND.

• PRESSURE ELONGATION CONSIDERATIONS AXIAL ELONGATION OF AN INTACT OUTBOARD NEIGHBOR TUBE U-BEND WAS CONSIDERED TO PERMIT ADDITIONAL UPWARD MOVEMENT OF A SEVERED TUBE U-BEND.

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MANUFACTURING CONSIDER ATIONS

• THE MANUFACTURING STUDY PERFORMED TO ESTABLISH A CONSERVATIVE VALUE FOR THE MAXIMUM GAP WHICH MIGHT EXIST UPON COMPLETION OF STEAM GENERATOR FABRICATION INCLUDED CONSIDERATION OF THE FOLLOWING ELEMENTS:

DRAWINGS PROCESS SPECIFICATIONS ASSEMBLY OPERATIONS REWORK OPERATIONS (TYPICAL)

MAXIMUM ALLOWABLE TOLERANCES

• THE KEY ELEMENTS IN THE MANUFACTURING TOLERANCE EVALUATION INCLUDED CONSIDERATION OF THE FOLLOWING:

o TUBE TO TUBESHEET FITUP o TUBE EXPANSION DUE TO ROLLING OPERATIONS o TUBE SCHEDULE TOLERANCES LEG TOLERANCE BEND RADIUS TOLERANCE OUTSIDE DIAMETER TOLERANCE o TUBE TRIMMING AND U BEND GAP ADJUSTMENT SPECIFICALLY PERFORMED TO MAINTAIN MINIMUM U-BEND GAPS IN LATER MODEL STEAM GENERATORS. THIS WAS DONE TO INCREASE THE GAP TO THE NEXT OUTBOARD NEIGHBOR TO MAKE IT CLOSER TO NOMINAL. THIS WOULD ALSO DECREASE THE GAP TO THE NEXT INBOARD NEIGHBOR TO ALSO MAKE IT CLOSER TO NOMINAL.

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SPECIAL ISSUES RELATED TO P* APPLICABILITY

• SAFE SHUTDOWN EARTHQUAKE (SSE)

EFFECTS OF LIMITING BENDING LOADS AND TUBE ROCKING ON VERTICAL DISPLACEMENT OF THE TUBE END IN THE TUBESHEET HAVE BEEN CONSIDERED FOR THE LOADING CONDITION WITH THE LIMITING EFFECT, I.E., SAFE SHUTDOWN EARTHQdAKE. FOR A TUBE WITH THE MAXIMUM SPAN LENGTH BETWEEN SUPPORTS TUBE UPLIFT EFFECTS WERE FOUND TO BE NEGLIGIBLE.

• DENTING OF STEAM GENERATOR TUBES ALTHOUGH TUBE DENTING IS NOT EXPECTED TO OCCUR IN MODEL D STEAM GENERATORS FOR A VARIETY OF REASONS, CONSIDERATION WAS GIVEN TO THE EFFECTS OF DENTING ON THE P' CRITERION. RELATIVE TO P* RESULTANT AXIAL MOVEMENT OF A SEPARATED TUBE WOULD BE THAT ASSOCIATED WITH ACCIDENT CONDITION MOTIONS AND IS LESS THAN THE MARGIN AFFORDED BY THE P* CRITERION.

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USAGE ISSUES REL ATED TO P' APPLICATION

• AXIAL VERSUS CIRCUMFERENTIAL INDICATIONS MAINTENANCE OF A FIXED TUBE END CONDITION IS AN ISSUE ONLY FOR A POSTULATED SEPARATED TUBE. FOR AXIAL INDICATIONS, PULLOUT FROM THE TUBESHEET IS NOT AN ISSUE.

BEHAVIOR OF AXIAL INDICATIONS AT OR ABOVE P* WOULD BE EXPECTED TO BE THE SAME AS FOR INDICATIONS ELSEWHERE IN THE FREE SPAN TUBE LENGTHS.

• ISTACT NEIGHBOR DEFINITION THE DEVELOPNENT ASSUSES THAT THE OUTBOARD NEIGHBOR TUBE IS STRUCTURALLY INTACT,I.E., IT DOES NOT CONTAIN INDICATIONS WHICH WOULD RESULT IN ITS INABILITY TO RESIST THE LOAD IMPOSED BY THE SEPARATED TUBE. THIS IS BASED ON TIIE EXTREhELY LOW PROBABILITY OF SIMULTANEOUS OCCURENCE OF THE POSTULATED LIMITING CONDITIONS, E.G., MAXIMUM GAPS, CIRCUMFERENTIAL DEGRADATION IN BOTH TUBES, AND 7_ERO FRICTIONAL RESTRAINT OF TUBE ENDS.

• EDDY CURRENT INSPECTION UNCERTAINTY THE CRITERION IS hEANT TO BE APPLIED TO A REPORTED LOCATION, OF A PRESUMED "CIRCUMFERENTIAL" INDICATION, BELOW THE TOP OF THE TUBESHEET WHICH CONSERVATIVELY ACCOUNTS FOR ECT SIGNAL INTERPRETATION UNCERTAINTY.

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TUBE LEAK AGE CONSIDER ATIONS NO ACTUAL' LEAK PATH WOULD BE EXPECTED DUE TO THE HARDROLLING OF THE TUBES INTO THE TUBESHEET. THEREFORE, A LEAK PATH WAS POSTULATED TO EXIST AND THE RELATIONSHIP BETWEEN THE LEAK RATE AT POSTULATED FLB AND SLB CONDITIONS WAS ASSESSED RELATIVE TO THAT AT NOMINAL PLANT OPERATING CONDITIONS.

• ACCIDENT RELATIVE TO NORMAL OPERATING LEAKAGE RATES THE FOLLOWING EFFECTS ARE SIGNIFICANT RELATIVE TO A POSTULATED LEAK SOURCE LOCATED P* OR MORE BELOW THE TOP OF THE TUBESHEET: .

o THE DECREASE IN THE LENGTH OF THE LEAK PATH ANNULUS, DUE TO THE PULLOUT OF THE POSTULATED TUBE END.

F o TUBE TO TUBESHEET LOADING DUE TO THE INCREASED PRESSURE WITHIN THE TUBE.

FOR AN INITIAL LOCATION OF A POSTULATED LEAK SOURCE A

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DISTANCE P' BELOW THE TOP OF THE TUBESHEET, THE DECREASE IN THE LENGTH OF THE LEAK PATH RESULTS IN AN INCREASE IN THE LEAKAGE OF APPROXIMATELY 10 PERCENT. THIS SMALL EFFECT WOULD' BE REDUCED SOMEWHAT BY THE PRESSURE EFFECT.

THEREFORE, THE EXISTING TECHNICAL SPECIFICATION LEAKAGE CRITERION IS CONSIDERED SUFFICIENT TO MAINTAIN CONDITIONS CONSISTENT WITH ACCIDENT ANALYSIS ASSUMPTIONS.

FOR AXIAL INDICATIONS, THE TUBE END IS STRUCTURALLY INTACT AND PULLOUT IS RESISTED. LEAK RATE WOULD THUS BE BOUNDED BY THAT OF FREE SPAN INDICATIONS.

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TUBES EXCLUDED FROM P* APPLICATION THE ANALYSIS FOR THE DEVELOPMENT OF P* IS BASED ON CONSIDERATION OF THE RESTRAINT AFFORDED BY A NEIGHBORING TUBE.

THERE ARE L CATIONS IN THE BUNDLE WHERE SUCH RESTRAINT IS NOT OR MAY BE ASSUMED TO NOT BE PRESENT.

• PERIPHERAL TUBE LOCATIONS THE PERIPHERAL TUBES IN THE BUNDLE DO NOT HAVE OUTBOARD NEIGHBORS. THE ANTI-VIBRATION BARS RETAINING RINGS COULD BE CONSIDERED TO AFFORD RESTRAINT, HOWEVER, THE BUNDLE DOES NOT FORM A SMOOTH UNIFORM SURFACE, THUS, NOT ALL TUBES WOULD BE AFFORDED RESTRAINT. IT IS THEREFORE CONSIDERED PRUDENT TO EXCLUDE ALL PERIPHERAL TUBES FROM APPLICATION OF THE P*

CRITERION.

• INTERIOR THE INTERIOR TUBES ADJACENT TO AND ON THE TUBELANE SIDE OF THE TUBE SUPPORT PLATE STAYRODS DO NOT HAVE AN ADJACENT OUTBOARD NEIGHBOR TO PROVIDE THE RESTRAINT FOR APPLICATION OF THE P* CRITERION.

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SUMMARY

'OF P' DEVELOPMENT AND APPLICABILITY

SUMMARY

ON THE BASI.S OF THIS EVALUATION, IT IS CONCLUDED THAT TUBES WITH EDDY CURRENT INDICATIONS IN THE TUBESHEET REGION BELOW THE P' CRITERION OF 1.282 INCHES CAN BE LEFT IN SERVICE REGARDLESS OF THE I1EPTH OF THE INDICATION, AND ARE STILL IN COMPLIANCE WITH THE REQUIREMENTS OF USNRC RG 1.121.

TUBES WITH EDDY CURRENT INDICATIONS OF PLUGGABLE MAGNITUDE AND LOCATED LESS THAN P* BELOW THE TOP OF THE TUBESHEET SHOULD BE REMOVED FROM SERVICE IN ACCORDANCE WITH THE PLANT TECHNICAL SPECIFICATION AND FREE SPAN APPLICATION OF RG 1.121.

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