Watts Bar, Unit 1 - American Society of Mechanical ...Case N-597-1, "Requirements for Analytical...

Tennessee Valley Authority, Post Office Box 2000, Spring City. Tennessee 37381-2000

William R. Lagergren, Jr.Site Vice President, Watts Bar Nuclear Plant

DEC 17 200310 CFR 50.55a

U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, D. C. 20555

Gentlemen:

In the Matter of ) Docket No.50-390Tennessee Valley Authority )

WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 - AMERICAN SOCIETY OFMECHANICAL ENGINEERS (ASME) SECTION XI, INSERVICE INSPECTION -REQUEST FOR RELIEF 1-RR-05 - APPLICATION OF CODE CASE N-597-1,REQUIREMENTS FOR ANALYTICAL EVALUATION OF PIPE WALL THINNING

In accordance with 10 CFR 50.55a(a)(3)(i), TVA is requestingrelief from specified inservice inspection (ISI) requirements inSection XI of the ASME Boiler and Pressure Vessel Code for WBNUnit 1. Enclosure 1 to this letter provides request for relief1-RR-05 for NRC review and approval for the use of ASME CodeCase N-597-1, "Requirements for Analytical Evaluation of PipeWall Thinning," Section XI, Division 1. The request for reliefis an alternative involving the use of the Code Case that has anacceptable level of quality and safety for this application.

Pursuant to the conditions of Regulatory Guide 1.147, "InserviceInspection Code Case Acceptability, ASME Section XI," Division1, Revision 13, TVA requests review and approval for applicationof Code Case N-597-1 for the location described. Code Case N-597-1 is conditionally acceptable for use as described in Table2 of Regulatory Guide 1.147, Revision 13. Condition 1 is met asTVA's Flow Accelerated Corrosion (FAC) Program is written to theprovisions of EPRI Nuclear Safety Analysis Center Report 2002L-Revision 2. Condition 2 is met by submittal of this request forrelief to use the Code Case. Condition 3 does not apply to thisapplication of the Code Case as this is a Class 2 component.

U.S. Nuclear Regulatory CommissionPage 2

DEC 17 2003

Condition 4 is met by scheduling this component for examinationin the Cycle 6 refueling outage. Condition 5 does not apply tothis application of the Code Case as the corrosion phenomenonhas been determined to most probably be due to FAC andassociated original construction counterbore machining. Noother corrosion phenomenon is suspected at this location.

Enclosure 2 contains details on the evaluation relative to theCode Case for the elbow. Enclosure 3 contains a copy of theCode Case preceded by the applicable conditions of RegulatoryGuide 1.147, Table 2.

TVA requests approval of this relief request for application ofCode Case N-597-1 by July 30, 2004, prior to the predicted wallthickness falling below the required minimum wall thickness inSeptember, 2004.

Enclosure 4 contains the commitments in this letter. If youhave any questions about this relief request, please contactP. L. Pace at (423) 365-1824.

Sincerely,

W. R. Lagergr n)

Enclosures1. Request for Relief 1-RR-052. Evaluation of Component 103BE2523. Regulatory Guide 1.147, Table 2 and Code Case N-597-14. Commitment List

cc: See page 3

U.S. Nuclear Regulatory CommissionPage 3

DEC 17 2003

cc (Enclosures):NRC Resident InspectorWatts Bar Nuclear Plant1260 Nuclear Plant RoadSpring City, Tennessee 37381

Ms. Margaret H. Chernoff, Project ManagerU.S. Nuclear Regulatory CommissionMS 08G9One White Flint North11555 Rockville PikeRockville, Maryland 20852-2738

U.S. Nuclear Regulatory CommissionRegion IISam Nunn Atlanta Federal Center61 Forsyth St., SW, Suite 23T85Atlanta, Georgia 30303

ENCLOSURE 1

WATTS BAR NUCLEAR PLANT (WBN) UNIT 1FIRST 10-YEAR INTERVAL

REQUEST FOR RELIEF 1-RR-05

SUMPARY: During implementation of WBN's Unit 1 Cycle 5Refueling Outage Flow Accelerated Corrosion (FAC)Program, ultrasonic testing (UT) detected a thinlocation in an American Society of MechanicalEngineering (ASME) Code Class 2 main feedwaterpiping elbow at the steam generator Loop 2 inletnozzle. A "topography map" of the thin areas wasmade using UT thickness measurements and the UTdata was evaluated both by CHECWORKS and analyticalmethods. Based on the UT thickness measurements,predicted wear rate, and analytical analysis, itwas determined that the predicted wall thickness(tp) will fall below the required minimum wallthickness (tmin) eleven months after startup fromthe Cycle 5 refueling outage. However, analysisdemonstrates the elbow meets the alternativeevaluation criteria of ASME Code Case N-597-1,Section -3600. This condition was documented on aProblem Evaluation Report in WBN's CorrectiveAction Program. The remaining three steamgenerator elbows to the inlet nozzles wereultrasonically examined and were found acceptable.

The Cycle 5 refueling outage UT of the elbow foundthe current wall thickness (teas) to be 0.639inches. Using an estimated wall thinning rate of0.025 inches/year (0.0375 inches/18 month cycle)(plus a ten percent safety factor), the predictedwall thickness tp at the Cycle 6 refueling outageis calculated to be 0.598 inches.

The allowable minimum wall thickness tn ascalculated by the equation specified in Code CaseN-597-1 Paragraph -3622.1(a)(1) is 0.613 inches.As noted, the predicted wall thickness tp of 0.598inches will fall below the allowable minimum wallthickness tmin of 0.613 inches. The minimum wallthickness is greater than ninety percent of theminimum wall thickness tmn as allowed by theprovision of the Code Case. Thus, TVA isrequesting review and approval for application ofthe Code Case N-597-1 as allowed by the conditionsof Regulatory Guide 1.147 Inservice Inspection CodeCase Acceptability, ASME Section XI, Division 1,Revision 13. Application of the Code Case providesan acceptable level of quality and safety for thisapplication. Therefore, pursuant to 10 CFR

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ENCLOSURE 1



50.55a(a)(3)(i), TVA is requesting approval of thisrequest for relief (1-RR-05) to use the Code CaseN-597-1.

1

Main Feedwater System

Unit:

System:

Component:

Code Class:

CodeRequirement:

CodeRequirementFor WhichRelief isRequest:

BasisFor Relief:

ProposedAlternative:

FAC Grid 103BE252, 16-inch nominal pipe sizefeedwater pipe mitered 45 degree elbow at the inletto Loop 2 Steam Generator

Class 2 Piping

ASME Section XI, 1989 Edition, IWA-4300

ASME Section XI, 1989 Edition, IWA-4300 provides aprocess for assessing a component for continuedservice after a defect has been removed. Thisprovision stipulates that where the sectionthickness has been reduced below the minimum designthickness, the component shall be repaired. As analternative, the component may be evaluated andaccepted in accordance with the design rules ofeither the Construction Code or Section III.

Regulatory Guide 1.147, Revision 13, conditionallyaccepted the use of Code Case N-597-1 subject tofive conditions. Some of these conditions requireprior NRC review and approval to continue to usethe Code Case.

As an alternative to the requirements of IWA-4300,TVA proposes to use the provisions of the ASME CodeCase N-597-1 for analytical evaluation of the mainfeedwater piping, FAC grid 103BE252, subject to theconditions incorporated into the acceptance of theCode Case in Regulatory Guide 1.147, Revision 13.

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ENCLOSURE 1

WATTS BAR NUCLEAR PLANT (WBN) UNIT 1

FIRST 10-YEAR INTERVAL


JustificationFor TheGranting ofRelief: A copy of the UT data obtained during the Cycle 5

Refueling Outage as printed from CHECWORKS programis shown in Attachment 2 of this enclosure. Theblank locations are either obstructions or wherethe UT examiner was unable to properly place thetransducer due to obstructions in confined accessspace. In addition to performing the normal FACUT for thickness on the grid, a one hundred percentUT scan at the toe of the weld (TOW scan) wasperformed. The lowest thickness reading and itslocation were recorded. The location of the "Al"(grid origin) is approximately at the top of thehorizontal portion of the elbow on the upstream end(end opposite that viewed in Photo 3). This placesRow "E" at the intrados and Row "N" at theextrados. With the configuration of this portionof the pipe loop, it would be expected that wearwould occur in the extrados portion of the subjectelbow and would be elongated in the direction offlow.

The UT data evaluator determined the wear for theelbow should be evaluated by the blanket methodsince the elbow was fabricated from bent pipe whichcould be expected to cause thickness variations ina circumferential direction. Also, it was decidedbands showing evidence of being countered-bored,(Bands 1, 2, 3, 9, and 10), would not be used todetermine the wear of the grid. Attachment 3 ofthis enclosure shows the results of weardetermination.

The UT data and the wear data obtained as describedabove were next entered into a spreadsheet.Attachment 4 of this enclosure shows a copy of thedata as entered into cells P16 (wear) and cellsW16, X16, and Y16 for the UT data. The wear andthe limiting thickness (the lowest UT reading) wereused to calculate the remaining service life,(Lrem), shown in cell T16. The Lrem was calculatedto be a time less than the 1.5 years required tooperate until Cycle 6 Refueling Outage - in fact anegative number.

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ENCLOSURE 1



The UT data and the physical configuration of thepipe in question indicates there was an extra longcounterbore applied to the upstream end of theelbow during construction and that Band 3 is atransition area between counterbore and non-counterbore. The thickness required aftercounterbore is a nominal 0.758 inches with atolerance of plus 0.005 inches and minus zeroinches. This thickness is only 0.037 inchesthicker than the Tcpt value of 0.721 inches. Also,during construction the weld was prepared manuallyon the outside diameter surfaces for nondestructiveexamination NDE). As seen in Attachment 1 of thisenlosure, the location and orientation of the"thin" areas are not typical of AC wear.

The following additional information is based uponsuggested content in an NRC memorandum, datedAugust 6, 2003, for relief requests where the wallthickness is less than tin.

1. Markup of piping isometric showing locationwhere piping is less than tn:

Attachment 5 of this enclosure shows thelocation of FAC grid 103BE252 on the mainfeedwater piping. The thin areas are locatedtoward the upstream end of the elbow and areshown in Attachment 1 of this enclosure.Attachment 1, page EAI-5 shows the thin areaof concern. The grid spacing is a three-inchsquare. Photo 1 shows an overall view of thenozzle, the elbow, pipe pup piece, and otherelbows, plus pipe restraint devices and ahanger. Photo 2 shows a close-up lookingbetween the restraint devices which shows aportion of the pipe pup piece, a portion of thesubject elbow, and a hanger. Photo 3 shows aclose-up of the subject elbow and the inletnozzle from the side opposite the view shown inPhotos 1 and 2. Each attachment shows the pipewhip restraint devices around the elbow.

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ENCLOSURE 1



2. Affected System

Main Feedwater System

3. System normal operating temperature = 440degrees Fahrenheit (F)Normal operation pressure = 1145 pounds persquare inch (psi)Design Pressure = 1185 psi

4. Pipe size and nominal pipe wall thickness(tnom) :

16-inch Schedule 80 (tnom = 0.844 inches)

5. Code-allowable tin,

The allowable minimum wall thickness t ascalculated by the equation specified in CodeCase N-597-1 paragraph -3622.1(a)(1) is 0.613inches. This equation is essentially the sameequation for calculating the minimum wallthickness based upon the allowable hoopstresses.

6. Current thickness and date measured:

tmea = 0.639 inches measured on September 16,2003

7. Estimated wall thinning wear rate:

0.025 inch/year (0.0375 inch/18 month cycle)

8. Predicted wall thickness (tp) at RefuelingOutage 6:

0.598 inches.

9. Discuss how pressure spikes associated withanticipated system transients are accounted forin establishing tmin-

The identified pressure surges due toanticipated system design transients areconsidered and bounded in establishing tn.For this piping the Feedwater Check Valve Slam

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ENCLOSURE 1



Transient loadings have also been considered asinput.

10. Provide licensee's basis for determining thewear thinning rate.

The UT data evaluator determined the wear forthe elbow should be evaluated by the blanketmethod since the elbow was fabricated from bentpipe which could be expected to cause thicknessvariations in a circumferential direction.Also, it was decided bands showing evidence ofbeing countered-bored (Bands 1, 2, 3, 9, and10) would not be used to determine the wear ofthe grid. Attachment 3 of this enclosure showsthe results of wear determination.

11. Provide licensee's criteria for repairing orreplacing piping and the basis for thecriteria.

TVA's FAC Program allows three options if thepredicted remaining service life is less thanthe amount of time until the next inspection.These options are:

a) shorten the inspection interval;

b) perform a more detailed stress analysis toobtain a more accurate value of theacceptable service life using theevaluation methods specified in TVA's CivilDesign Standard, Structural Evaluation ofWall Thinning in Pipe Due to FlowAccelerated Corrosion: and,

c) repair or replace the component.

In addition, for piping and components withpredicted wall thinning that satisfies theacceptance criteria for continued service, theProgram requires monitoring areas containingFAC degradation during successive examinationsuntil repair or replaced with a FAC resistancematerial and determine the frequency of futureexaminations by the FAC wear rate or remainingservice life calculated from examination data.

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ENCLOSURE 1



For this application, the current FAC Programrequires this elbow to be inspected during thenext refueling outage. The Program requiresthat when the predicted remaining service lifeis shorter than the time until the next outage,the appropriate corrective action document beinitiated. A WBN Problem Evaluation Report wasinitiated during the Cycle 5 refueling outage.

WBN's planned action regarding FAC grid103BE252, pending approval of this request, isto:

a) continue operation until the Cycle 6refueling outage;

b) during the Cycle 6 refueling outage,ultrasonically examine this elbow to obtaina new set of UT data, obtain a refined wearrate and perform a new analysis; and,

c) based on the Cycle 6 data, determinewhether to replace the elbow or continue toimplement Code Case N-597-1 using therevised (new) analysis.

12. Discuss what evaluation methods and criteriathe licensee plans to use for performinganalytical evaluations of pipe wall thinning inClass 1 carbon steel piping subjected to FAC.

WBN has no Class 1 carbon steel piping withinthe FAC Program.

13. Discuss what evaluation methods and criteriathe licensee plans to use for performinganalytical evaluations of pipe wall thinning innon-Code Class 1 carbon steel piping subjectedto FAC.

Analytical structural evaluation of piping thatis subjected to FAC and is within the scope ofthe WBN ASME Section XI Program is based uponsatisfying design basis stress criteria per theCode of Record for the piping (i.e., ASME Class2 or Class 3). Specifically, this requires the

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ENCLOSURE 1



determination of the minimum piping componentwall thickness that satisfies all pertinentstress requirements including hoop stress dueto pressure and longitudinal stress due topressure and moment loading for all applicableload combinations. In addition, the minimumrequired wall thickness to satisfy design basisstress criteria is screened against a limitingthickness of 30 percent of the pipe nominalthickness and the larger value is used todetermine remaining life in the component.This overall approach is summarized in TVACivil Design Standard DS-C1.2.5, "StructuralEvaluation of Wall Thinning in Pipe Due to FlowAccelerated Corrosion" which was developed toprovide a consistent evaluation process fordetermination of a required thickness thatsatisfies design basis stress criteria and, assuch, it provides a rational basis forrepair/replacement decisions.

ImplementationSchedule: The alternative to apply Code Case N-597-1 to

FAC Grid 103BE252 is requested for the durationof time that the analytical evaluation cansupport the acceptability of the component oruntil it is repaired or replaced.

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ENCLOSURE 1


FIRST 10-YEAR INTERVALREQUEST FOR RELIEF 1-RR-05

PHOTO 1

OVERALL VIEW OF MITERED ELBOWWELDED TO STEAM GENERATOR #2 INLET NOZZLE

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ENCLOSURE 1




PHOTO 2

VIEW OF PIPE PUP PIECE (LEFT)AND PORTION OF MITERED ELBOW (RIGHT)

BETWEEN RESTRAINT DEVICES

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ENCLOSURE 1



PHOTO 3

........... ,..

VIEW OF MITERED ELBOW VIEWEDLOOKING AWAY FROM STEAM GENERATOR NOZZLE

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ENCLOSURE 1



LIST OF ATTACHMENTS

Attachment 1

Attachment 2

Attachment 3

Attachment 4

Attachment 5

UT Data Report

CHECKWORKS UT Data Sheet

Wear Rate Summary

UT and Wear Data Analysis

Grid Isometric

ENCLOSURE 1ATTACHMENT 1


REQUEST FOR RELIEF 1-RR-05UT DATA REPORT

TENNESSEVALX | DIVIS ~lTRASONIC I CAMIBRATION REPORTAUTHOM~Y CALIBRATION NO. N

PRO1ECT WBN UNIT: I CALIBRATIONDATE PROC.: I N-UT- 26 REVJT.C:21103-01 CALBLOCK NO.: J774

TYPE: 9f39o S _ s >ts '16'INSTRUVMET I TRANSDUCERDATA CAL BLK- TEMP.: 84°

1ERMOMETERS/N: 562779IXSRUMENT MANUF.: IMA THRMt CAL DUE DATE: 06-16-04SERIALNO.: E36027 DUEDATE: 08-504 COLPLANT: ULTRAGELIITRANSDItCERMANUF.: BA BATCRNO. 01225SERLALNO.: 60VL31j o

SIZE: . 8 4g FREQ.: 8. mhz INSTRUIENT SETINGSCABLE TYPE PIm LENIGTI 72" PROBE: F

THICK CAL.: iFTI 2PFT.25Dt~ ,)?bRANGE /,O oD inches

- - - A e = = sVELOCIT: iJuS_ _ I I _ _ _ A GAIN M DUJ

M TCG MODE: SINGLE OP DUAL _

_ _L RECTIFY: POSITIVEI NEGATIVE 1T FULDU AMLITUDE NORMAL D SCALE O

DISPLAYWIDTH Jo ad inches CALIBRATION TIESINTALCALTNIE: ,230

(1) VERMCAnONTS _F". REFLECTOR a,6 GAIN 72 dB 1)/ 3 2) | 3) 4'AMPL / % ETALPATs'd inches 5) 6) 17) 8)

FINAL CAL TNI5 D (2) COMPN(S) EXAED TRW

REF. EFLECTOR _ A_ GAIN 7C dB /0; &E2SZ ______

AMPL /00 % METALPATH .7-0 inhes

COMMENTS: rnAPpl'c FLouw -yq ssT.I.31.21 -u B .7",; ,7d0" __

EXANMOL6, LvL ANI:

SEXAME: > Lvi. DATE:

RE,Ve /, -k LAi. L PAGE 17 d 22//

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REQUEST FOR RELIEF 1-RR-05CHECKWORKS UT DATA SHEET

CompanyPlantUnitDB Nmc

: Tenr.eacee Valley Authority: atte Bar: I: TVAhB

Report ate: 12-DEC-03 Time: 09:36:47

CHECAORPKS FAC Vrainn 1.0r (Piiild 7S)

*** UT Matri. ***,*..-...... .**

J.TNR NAMP : FW5: Main P oop #2COMPONENT NAM13 s 103a2s3OUTAGE AME : UCS RFO-5SECTION : U/S MainThom - 0.844 (in), Tscreen - 0.721 (in)VGrid dal

1

345678910

A0.7030.7801.180

B0.7100.7781.092

C0.7370.7570.762

D0.7730.7620.769

E0.7390.7610.772

F0.744O.7600.789

G0.8050.7570.849

R0.8330.811.142

I0.7860.7911.074

1.205 1.192 1.163 1.034 1.081 1.182 1.221 1.2281.059 1.040 1.006 0.996 0.979 1.066 0.979 0.9720.810 0.829 0.815 0.99 0.743 0.'96 0.738 0.'147

1.2951.2670.927O.7V/2

0.7721.2950.5230.9870.227

0.7410.7800.925

1.1971.1701 .13S0.951o. 183

0.7411.1970.4560.9480.191

K0.7950.7661. C77

1.1451.0961. C840.8790. 869

0.7661.1450.3790.9640.152

L0.7910.7141.1111.1021.1141.0831.0771.0670.9050.901

0.7141.1140.4000.9870.147

M0.7590.7111.1191.0991 .1031.0811.0841.0610.9440.830

0.7111.1190.40E0.9790.157

N0.7450.7211.1221.1141.0911. 891.0821.0780.9570.969

0.7211.1220.4010.9870. 155

a0.7420.7721.1371.135

1.1301.1200.9720.878

0.7421.1370.3950. 9PE

0.169

p0.7440.7371.1171.119

1.1271.109

0.9960.89'

0.7371.1270.3900.9810.168

Q0.7230.7681.1191.149

1.2191.1791.3180.76

Min0.7030.7110.7621.0991 .0911.0811.0771.0610.8510.V38

Max0.8330.8161.1831.1491.1141.1971.2951.2671.0660.901

Del0.1300.1050.4180.0500.0230.1160.2180.2060.2150.163

Ave0.7570.7611.0091.1201.1031.1191.1421.1450.9730.821

Dev0.0350.0270.1570.0190.0120 . es0.0740.0650.0590.054

Min 0.703Max 1.205Del 0.502Ave 0.956Dev 0.219

0.7101.1920.4S20.9390.192

n.7371.1630.4260.8730.173

0.7621. 0940.3 220.8640.140

0.7391.0810.3420.8460.147

0.7441.120.4380.8900.186

0.7381.2210.4830.9910.183

0.7471.22S0.4 810.9S60.194

0.7231.2190.4961.3060.194

SECTION SU11MARYMinimum Thickrens -Maximum Thickr~eea -

Delta -

Average Thickr.ess -Standard Deviation -

0.7031.2950.5920.9500.17'

Minimum at l,AMaximum at 7,I

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REQUEST FOR RELIEF 1-RR-05WEAR RATE SUMMARY

CMSIy : T =ze83 Vall-y thorzy Repor: Dt. a 25-VC-03 Time 13.58:2F1Zat a h@tti irm1t t I crHr-kA= FAC Versloa .oc :3tld 75)D3 Nama: TIOiSV

*~ fl au.ry .*-

Cogo&ent :103S252LiI. F52 Hai. FI Locp 2C-cm-try riPe S 45-DIl EOTW

-> t-ction: U/S HalScn - 0.34 In), Tinit - 0.000 (in), Tcreen - 0.721 (1.,

parocls) Grld Sl. 14o. of Avg. Standard Kil. k. H.x. Thk. Total u..r Total Svr.(RXC) Pollts T.k. DLv. IRxCI C5XC; Life Was: aIthod Hours.

UIOC5 R3a-S l0x17 125 C.95C 0.171 C.701:: A: 1.29;t7 : 0.1,: l----- 65472.C

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ENCLOSURE 1ATTACHMUENT 4


REQUEST FOR RELIEF 1-RR-05UT AND WEAR DATA ANALYSIS

,

I C I D E F G H | I J I K I L I M I N 0 P I Q I R I S I T1 The below FAC grid UT data has been reviewed. evaluated for adeqluacy, compared to the acceptance criteria, and are acceptable for continued service. These grids may be reinsulated2 and returned to service.3 Original signed by Evaluator Original signed by Verifier4 Evaluata pmn4 .fbal. adle. NEAJ.tN VW91 fXef Ipfi. 4ae). Nt-UAN

5 Definitions:6 LOC' = for Tees, Reducers. and Expanders, U-Upstream Main Run. D=Downstream Main Run. B=Branch, L=Large diameter end, and S=Smal diameter end.7 Taccpt-Acceptable Minimum Thickness, calculated value unless indicated. fllm=RFO-5 minimum measured thickness. Wmeas=Wear, measured, fram CHECWORKS. Lremwpredicted Life

8 remaining-(Tlim-Taccpt)f(WRcorr SF). WRcorr=Wrmeas x (greater of WR current/Wravg or 1). Repair or Replaco?=Lrem>1.5. Expand Sample?=Tflmo-(0.5Tnom) and (Lrem'3.0).910 WO No.: 02-012720-000

12 O 1.0 0.875 0.5 Ltime Tamcpt WRcurrent WRavg WRcurrent Rcorr T.. Wmeas WRmeas Repair or Expand . I-13 C _______ _ .....1............. - (years) (inch) (in0 (inyr) |VVRavg) Ci. . (inch) finlyr) Replace? Sample? Lrem, yrs14 Loop 2 Inside Crane Wall - Class B15 5-075 103BP251 0.844 0.739 OA22 7.52 0.613 26.957 30.440 0.886 0.018 0 137 0.018 NO NO -; 4,-16 5-076 103BE252 0.844 0.739 0.422 7.52 0.721 29.485 33.294 0.886 0.025 YES YES 2.0)17 5-077 1038N253 0.844 0.739 0.422 7.52 0.490 33.697 38.050 0.886 00100 0.013 No NO 16.51 8 Comments:19 U/S T.O.W Scan value on 103BE252 is from mapped/scanned area. U/S end of elbow, and weld to P251, are covered by support.20 U/S T.O.W Scan value on 103BP251 is from T.O.W scan around weldolet. D/S end of pipe, and weld to E252, are covered by clamp..21 See PERs 03-016397-000 (specific) and 03-016393-000 (generic). One local spot (see map) shows a small area with 0.639" thickness,22 Further evaluation by Civil Engineering has determined 103BE252 is acceptable for continued service for 11 months and will be dispositioned23 in accordance with corrective actions of PER 03-016397-000.2425 M16 = IF(OR(K16=-,LlG="').-NA-.(K16/L16)) T16 = IF(OR(O1 6="NA"N 1 6="NA"),'NA,(01 6-JI 6)/(NI 6'1. 1))26 N16 = IF(Q16="NA","NA".(MAX(1,M16)yQ16)) V16 = Input27 016 = IF(MIN(W16:Y16)>0,MIN(WI6:Yi6),"NA' t) W16 = Input28 P16= Input X16= Input29 Q16 = IF(P16="NA",-NA",P16/116) Y16 = Input30 R16 = IF((T16>1.5),"NO","YES') Z16 = 0.3F1631 S1 = IF(AND(T1 6>3, 01 6>H1 6),"NO","YES") AA1 6= IF(J1 6='"',"',IF(Zl 6>J1 6+0.0005,"Error,"OK"))

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ENCLOSURE 1

ATTACHMENT 4


REQUEST FOR RELIEF 1-RR-05UT AND WEAR DATA ANALYSIS

C D E V W X Y Z AA1 The below FAC grid UT data has

2 and returned to service. . . Not*~pnti'd rt''.t.

345 Dofnnltons: cW Ctal:-T-minT Measured6 LOC' = for Tees. Reducers. and Evel US .d DS:4.:

7 Toccpt=Acceptable Minimum T h11th .odi'>-, .i'wf ., '..'

8 rernaining=(Tlim-Taccpt)(W Toe Grid Toe Oi 0.3BAnd o of ... ; Tnorn

1 FIL Grid Numb r L WTmin

12 ~~~0 Pon~ nh ic nhCheck

14 Loop 2 Insid Cr15 5-075 103BP251 BA 0.763 0.707 OK

16 5-076 103BE252 = BL 639 1 3 .77 ... OK17 5-077 103BN253 .BA. 0*731 0.744 .. OK

18 Comments:

19 UIS T.O.W San 20 UIS T.O.W San 21 See PERS 03-01622 FUrther evaluation23 in acordance wit24

2526=

28

29303 1

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REQUEST FOR RELIEF 1-RR-05GRID ISOMETRIC

ENCLOSURE 2



EVALUATION OF WBN FLOW ACCELERATED CORROSION (FAC) PROGRAMCOMPONENT 103BE252

RELATIVE TO ASME CODE CASE N-597-1

Background and Objective:

This evaluation addresses flow accelerated corrosion (FAC)induced wall thinning for WBN FAC Component 103BE252, anAmerican Society of Mechanical Engineers (ASME) Section III,Class 2, 16-inch Schedule 80 (i.e., Nomial thickness (tnom) =0.844 inches), elbow located in Loop 2 of the Unit 1 MainFeedwater System. This elbow is fabricated from SA-333 GR 6material. Design pressure and temperature are 1185 poundsper square inch (psi) and 600 degrees Fahrenheit (F),respectively.

Based on wall thickness data taken during the Cycle 5refueling outage in September 2003 (i.e., 0.639 inchesminimum measured remaining thickness) and wear ratescomputed using WBN FAC Program methods (including tenpercent safety factor), the minimum projected wall thickness(tp) at the time of Refueling Outage-6 (i.e., 1.5 yearsafter Refueling Outage-5) was determined to be 0.598 inches.This evaluation provides technical justification that tpsatisfies ASME Code Case N-597-1 requirements. Eachpertinent section of the code case is addressed separatelybelow:

Section -3500 - Wall Thickness Acceptance Standards:

Per Section -3500 (a)(1), the acceptance standard that tp(0.598 inches) must be greater than 0.875 tom = 0.739 inchesis not satisfied for this component. However, tp issignificantly greater than the limiting thicknessrequirement specified in Section -3500(d) for ASME Class 2components (i.e., tp = 0.598 inches > 0.2 t = 0.169inches). Thus, further evaluation is performed inaccordance with Section -3600, "Analytical Evaluation forClass 2 and Class 3 Piping Items,O as permitted by Section -3223, "Acceptance by Engineering Evaluation."

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ENCLOSURE 2



Section -3600 - Analytical Evaluation for Class 2 and Class3 Piping Items

Section -3621 - Evaluation of Pipe, Elbows, BranchConnections and Reducers:

Per Section -3621(d), the ratio, R/tp = 8.0 inches/0.598inches = 13.4, is less than 50. Thus, the potential forbuckling requires no further evaluation.

Section -3622 - Thickness Evaluation:

In determining acceptance in accordance with Section -3622,the wall thickness data taken during Refueling Outage-5 isused with the wear rate (plus a ten percent safety factor)applied for the length of service expected (i.e., 1.5 yearsuntil Refueling Outage-6) to determine projected thickness.For WBN FAC component 103BE252, a minimum projected wallthickness value (tp) of 0.598 inches has been computed forRefueling Outage-6. Considering the design pressure (P =1185 psi) and allowable stress for the elbow material (S =15000 psi @ 600 degrees F), the equation from theconstruction code is used to determine the requiredthickness (tan) as follows:

t = P Do = 1185 psi (16.00in) 0 613innun 2 (S + y P) 2 [15000 psi +0.4(1185 psi)]

For acceptability, Section -3622.1(a) specifies that tp maynot be less than ninety percent of tin.

to, 0.598 in = 0.976 > 0.900

t-n 0.613in

Since the ninety percent tin criteria is satisfied, therequirements of Section -3622 are satisfied without furtherevaluation.

Section -3623 - Piping Stress Evaluation:

The effect of the pipe longitudinal pressure and bendingstresses was evaluated for WBN FAC Component 103BE252 usinga detailed stress analysis in accordance with theConstruction Code of Record and the requirements of Section-3623. This detailed stress analysis used as input the

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Refueling Outage-5 measured thickness data for cross sectionin question including the wear rate (plus a ten percentsafety factor) applied for the length of service expected(i.e., 1.5 years until Refueling Outage-6). The stressanalysis methodology applied accounted for reduced sectionproperties and induced bending due to neutral axis offsetconsidering the projected thicknesses at the time ofRefueling Outage-6. Also, the stress evaluation accountedfor the impact on the elbow stress intensification factor(Section -3623.4) due to the projected wall thickness atRefueling Outage-6 and the intensification factor wasincreased accordingly. Pipe bending loads were taken fromthe analysis of record which is a rigorous static anddynamic qualification of the piping that demonstratessatisfaction of ASME Class 2 requirements. Although, theanalysis of record assumes nominal thickness for all pipingcomponents, the 1.143 stress allowable factor permitted inSection -3623.1 was not used in the structural evaluation.This stress evaluation showed that the applicable Code ofRecord ASME Section III, Class 2 equations remain withinrequired allowable stresses when considering the reducedthickness profile of the affected cross section as projectedto Refueling Outage-6. Specifically the maximum primary andprimary plus secondary stress ratios (applied/allowable)were found to be 0.917 and 0.865, respectively. Thus, therequirements of Section -3623 are satisfied.

Section -3624 - Evaluation of Branch Connections:

The location of FAC Component 103BE252 is a piping elbow andnot a branch connection, therefore, the requirements ofSection -3624 are not applicable.

Section -3625 - Evaluation for Cyclic Operation:

This component was evaluated for cyclic operation usingSection -3625(b). For the WBN main feedwater system, reviewof the stress range reduction factors of Table 3625-1indicates that a factor of 1.0 would be applicable since theapplicable number of full temperature thermal cycles for oneoperation cycle is much less than the 650. In addition,projected thicknesses at Refueling Outage-6 have beenincluded in the development of the stress intensificationfactor for the Section -3623 analysis discussed above whichdemonstrated satisfaction of pertinent stress equations andhence, suitability for cyclic service in accordance withASME Class 2 piping requirements. For Section -3625(c),

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ENCLOSURE 2



evaluation of ASME Section III, NC-3600, Equation 11 (i.e.,sustained primary plus thermal expansion stress) indicatesthat the revised stress ratio (i.e., applied/allowable)remains less than 1.0 for the analysis performed in theSection -3623 evaluation. This ensures that the localoverstrain in the thinned region for the combination ofmaximum sustained plus thermal expansion stresses have beenadequately considered. Thus, the requirements of Section -3625 are satisfied.

Conclusion:

As discussed above, the pertinent elements of the Code CaseN-597-1 evaluation have been applied to address theprojected thickness of WBN FAC Component 103BE252 at thetime of Refueling Outage-6. For each element, acceptabilityhas been demonstrated in accordance with N-597-1requirements. Thus, it is concluded that this pipingcomponent is acceptable for service without repair orreplacement until the WBN Unit 1 Cycle 6 refueling outage.

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ENCLOSURE 3



REGULATORY GUIDE 1.147 TABLE 2

ANDAPPLICABLE TO AND COPY OF ASME CODE CASE N-597-1

ENCLOSURE 3




CODE TABLE 2, CONDITIONALLY ACCEPTABLE SUPPLEMENT/CASE SECTION XI CODE CASES EDITION

NUMBER CONDITION. ._

N-586 Alternative Additional Examination Requirements for Class , 2, 5/98Eand 3 Piping, Components, and Supports, Section Xl, Division 1

The engineering evaluations addressed under Item (a) and theadditional examinations addressed under Item (b) shall beperformed during this outage. If the additional examinationsperformed under Item (b) reveal indications exceeding theapplicable'acceptance criteria of Section XI, the engineeringevaluations and the examinations shall be further extended toincluded additional evaluations and examinations at this outage.

N-593 Alternative Examination Requirements for Steam Generator 11/98ENozzle to Vessel Welds, Section Xl, Division

Essentially 100 percent (not less than 90 percent) of thee .examination volume A-B-C-D-E-F-G-H must be nspected.

N-597-1 Requirements for Analytical Evaluation of Pipe Wall Thinning, 2/01 ESection Xl, tDivision I

(1) Code Case must be supplemented by the provisions of EPRINuclear Safety Analysis Center Report 202L-R2. April 1999,'Recommendations for an Effective Flow Accelerated CorrosionProgram,' for developing the Inspection requirements, the*method of predicting the rate of wall thickness loss; and thevalue of the predicted remaining wall thickness. As used inNSAC-202L-R2, the terms should' and shall" have the sameexpectation of being completed.(2) Components affected by flow-accelerated corrosion to whichthis Code Case are applied must be repaired or replaced inaccordance with the construction code of record and Owner'srequirements or a later NRC approved edition of Section III ofthe ASME Code prior to the value of t reaching the allowableminimum vall thickness, t,,, as specified In -3622.1 (a)(1) of thisCode Case. Alternatively, use of the Code Case is subject toNRC review and approval.(3) For Class 1 piping not meeting he criteria of -3221, the useof evaluation methods and criteria Is subject to NRC review andapproval.(4) For those components that do not require immediate repairor replacement, the rate of wall thickness loss is to be used todetermine a suitable inspection frequency so that repair orreplacement occurs prior to reaching allowable minimum wall

I___________ thickness, t,.

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ENCLOSURE 3




. CODE TABLE 2, CONDITIONALLY ACCEPTABLE 3UPPLEMENTICASE SECTION XI CODE CASES EDITION

.NUMBER CONDITION

N-597-1 Requirements for Analytical Evaluation of Pipe Wall Thinning, 2/01 E(continued) Section Xl, Division 1

(5) For corrosion phenomenon other than flow acceleratedcorrosion, use of the Code Case is subject to NRC review andapproval. Inspection plans and wall thinning rates may bedifficult to justify for certain degradation mechanisms such asMIC and pitting.

N-599 Alternatives to Qualification of Nondestructive Examination 2198EPersonnel for Inservice Inspection of Metal (Class MC) andConcrete (Class CC) Containments, Section Xl, Division

This Code Case may not be used when a licensee updates tothe 1992 or later Edition of Section XI that requires the use ofANSI/ASNT CP-189, "Standard for Qualification and Certificationof Nondestructive Testing Personnel."

N-606-1 Similar and Dissimilar Metal Welding Using Ambient 6/98ETemperature Machine GTAW Temper Bead Technique for BWRCRD Housing/Stub Tube Repairs, Section Xl, Division 1

Prior to welding, an examination or verification must beperformed to ensure proper preparation of the base metal, andthat the surface is properly contoured so that an acceptable weldcan be produced. The surfaces to be welded, and surfacesadjacent to the weld, are to be free from contaminants, such as,rust, moisture, grease, and other foreign material or any othercondition that would prevent proper welding and adversely affectthe quality or strength of the weld. This verification is to berequired in the welding procedures.

N-616 Alternative Requirements for VT-2 Wsual Examination of 6/98EClasses 1, 2, 3 Insulated Pressure Retaining BoltedConnections, Section XI, Division 1

(1) Insulation must be removed for VT-2 examination during thesystem pressure test-for any 17-4 PH stainless steel of 410stainless steel stud or bolt aged at a temperature below 1 1000For with hardness above R. 30.(2) For A-286 stainless steel studs or bolts, the preload must beverified to be below 100 Ksl or the thermal insulation must beremoved and the Joint visually examined.(3) For nuts conforming to SA-194; removal of the insulation forvisual Inspection is not necessary.(4) Prior to conducting the VT-2 examination, the provisions ofIWA-5213, "Test Condition HoldingTim-es." 1989 Edition, are tobe followed.

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CODE CASE N-597-1

CASE

N-597-1CASES OF ASMIE BOILER AND PRESSURE VESSEL CODE

Approval Date: September 7, 2001

See Numeric Index for expirationand any reaffirmation dates.

Case N-597-1Requirements for Analytical Evaluation of PipeWal ThinningSection XI, Division 1

Inquiry: What requirements may be used for analyti-cal evaluation of Classes 1, 2 and 3 piping itemssubjected to internal or external wall thinning?

Reply: It is the opinion of the Coirnittee that thefollowing rules may be used.

-1000 SCOPE

This Subsection provides requirements for analyticalevaluation of Classes 1, 2, and 3 piping items (e.g.,piping and fittings) with internal or external wall thin-ning. These requirements are applicable to nonplanarflaws.

value, tp, may be used in determining acceptabilityfor continued service. Methods of predicting the rateof wall thickness loss and the value of :, shall be theresponsibility of the Owner.

.3220 Acceptance

-3221 Acceptance By Examination

Piping items whose examination and evaluation re-sults reveal that t, meets the acceptance standards of-3500 or the Construction Code are acceptable forcontinued service. When these criteria are not met, thealternatives of -3222, -3223, and -3224 may be used.Fig. -3220-1 shows a flow chart of the acceptancealternatives.

-3222 Acceptance by Repair/ReplacementActivity

Piping items whose thickness is less than that requiredby -3500. -3223, -3224 shall be corrected by a repair/replacement activity.

.3223 Acceptance by Engineering Evaluation

Piping items whose examination and evaluation re-sults reveal that the criteria of -3221 are not satisfiedmay be accepted for continued service by engineeringevaluation.

(a) For Class I piping items, this evaluation shallbe conducted in accordance with evaluation methodsand criteria developed by the Owner.

(b) For Classes 2 and 3 piping items, an acceptableevaluation method and criteria are provided in -3600.Alternative evaluation methods and criteria may bespecified by the Owner.

.3224 Acceptance by Reduction of Time to NextExamination

Piping items whose examination and evaluation re-sults reveal that the criteria of -3221 are not satisfied,are acceptable for continued service when the time tothe next examination for the affected piping items isreduced such that the acceptance criteria of -3221 or-3223 are met using the tp for the reduced examinationperiod.

-3000 ACCEPTABLE STANDARDS

-3100 Preservice Examination

Piping items examined prior to commercial serviceare acceptable for service when the measured wallthickness meets the requirements of the ConstructionCode.

-3200 Inservlce Examination

-3210 General

Upon completion of pipe wall thickness examinations,the predicted remaining wall thickness, tr, at the timeof the next scheduled examination shall be calculatedfor piping items under evaluation. The predicted re-maining wall thickness Is the spatial distribution ofwall thickness remaining throughout the piping itemand may have a unique value at any given locationon the piping item. Alternatively, the minimum predicted

985 SUPP. 2 - NC

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)

N-597-1CASES OF ASME DOILER AND PRESSURE VESSEL CODE

FIG. -3220.1 ACCEPTANCE FLOW CHART

SUPP. 2 - NC 986

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)

N-597CASES OF ASME BOILER AND PRESSURE VESSEL CODE

Required Thickness

Piping item Reference

Straight pipe -3600(al(1)

Elbows -3500tsl(1)

Reducer3 -2500(al(21

Tease -3500n)13)

Branch -3500(a113)connections1

Designed Item -3500(a114)

Other items -3GOO(bl

1Altemate of -3600Cal) may be used.

Thickness Limit

Code class Reference

I -3=O.(cl

2 -3500(d)

3 _3500(C)2

2 Atemate criteria may be developed Inaccordance with -3500(M).

FIG. .3500-1 WALLTHICKNESSACCEPTANCESTANDARDFLOW CHART

-3500 WaU Thickness Acceptance Standards

A flow chart for the acceptance standards is shownin Fig. -3500-1.

(a) A Class 1, 2, or 3 butt welded pipe, elbow,branch connection, or reducer piping item is acceptablefor continued service without further evaluation whentp at all locations on the piping item meets the followingrequirements.

(1) For straight pipe and elbows purchased to anominal pipe specification with an allowable wall thick-ness undertolerance of 12.5%, t shall be not less than0.875 ,,,, except that, for Class I short radius elbows,an evaluation shall be conducted to show that therequirements of N-3642.2 are net.

(2) For the small end of concentric and eccentricreducers. r, shall be not less than 0.875 ,,,, for thepipe size at the small end. For the large end, the largeend transition and the conical portion, t, ihall not beless than 0.875 tl for the pipe size at the large end.For the small end transition, the required thicknessshall be gradually reduced from that required at thelarge end to that required at the small end (see Fig..3622-1).

(3) For tees and branch connections, r, shall benot less than 0.875 t.,3 for the same size pipe forregions outside the limits of reinforcement required bythe Construction Code used in the evaluation. Forregions within the limits of reinforcement, t, shall be

917

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)


not less than the thickness required to meet the branchreinforcement requirements of the Construction Code.

(4) For regions of piping items designed to specificwall thickness requirements, including designed weldcounterbores and regions with integral reinforcement,4r shall be not less than the minimum design thickness,including tolerances and excluding any corrosion allow-ances. specified in the original design analysis for thepiping item.

(5) As an alternative to the requirements of-3500(a)(2) and -3500(a)(3), for reducers, tees, or branchconnections purchased to fitting standards allowed inTable NB-3132-1 and for which baseline as-installedthickness measurements exist. r, shall not be less than0.875 times the as-installed thickness measurements,except that the thickness shall not be less than 0.875 tnC|-

(b) Acceptance criteria for Class 1 2, and 3 pumps.valves, flanges, reducing elbows. socket weld fittings,and any other piping items not covered by -3500(a)shall be the responsibility of the Owner.

(c) For any Class I piping item, when 4, at anylocation is less than 0.3 t.o. further evaluation isbeyond the scope of this Case.

(d) For any Class 2 piping item, when t, at anylocation is less than 0.2 :,,,, further evaluation isbeyond the scope of this Case.

(e) Except as provided in (1 below, for any Class3 piping item, when t4 at any location is less than 0.2t,,, or 0.5 :,.,, whichever is less, further evaluationis beyond the scope of this Case. Lee value of t-, ,shall be determined in accordance with -3600.(19 As an alternative to -3500(e), decreased wall

thickness. including local through-wall leakage in Class3 piping items whose maximum operating temperaturedoes not exceed 200'F and whose maximum operatingpressure does not exceed 275 psi may be accepted.Evaluation methods and acceptance criteria shall bespecified by the Owner.

(b) Analytical evaluations shall be conducted usingthe predicted wall thickness, t4, at the next examinationof the piping item. The methods used to determine rpare the responsibility of the Owner.

(c) A piping item is acceptable for continued serviceif the minimum pipe wall thickness, branch reinforce-

*ment requirements, and piping stress criteria of theConstruction Code used in the evaluation are met forall specified loading conditions.

(d) As an alternative to -3610(c), butt welded pipe,elbow, branch connection, and reducer piping itemsmay be evaluated in accordance with -3620.

(e) Alternative evaluation of pumps, valves, flanges,and other piping Items are the responsibility of theOwner.

(t) Piping items under evaluation with r,, exceedingthe acceptance standards of -3500 and satisfying -3600shall be monitored for continued degradation. The fre-quency and means of monitoring for degradation arethe responsibility of the Owner.

-3620 Evaluation of Pipe, Elbows, BranchConnections, and Reducers

-3621 General Requirements

(a) The evaluation shall meet he requirements of-3622 and -3623.

(b) For a branch connection or tee, the region withinthe limits of reinforcement defined in the ConstructionCode shall meet the requirements of -3624.

(c) Evaluations shall be conducted using the appro.priate piping equations, loadings, load combinations,allowable material properties, and other acceptancestandards from the Construction Code used in theevaluation, except as specifically modified by this Case.

(d) When the ratio R, is greater than 50, thepotential for buckling of the thinned region shall beevaluated. Evaluation methods and acceptance criteriashall be specified by the Owner.

-3600 Analytical Evaluation for Class 2 andClass 3 Piping Items

-3610 General Requirements

(a) Analytical evaluations shall be conducted in ac-cordance with Construction Code. Later Code Editionsand Addenda may be used. Use of later Code Editionsand Addenda shall be reviewed for acceptability to theregulatory and enforcement authorities having jurisdic-tion at the plant site.

-3622 Thickness Evaluation

-3622.1 Evaluation for Minimum Wall Thickness

(a) Except as provided in -3622.1(b), the value ofrp at any location shall not be less than 90% of eminimum wall thickness of the piping item, rj, requiredfor design pressure, defined in the Construction Codeused in the evaluation, exclusive of any additionalcorrosion allowance.

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ENCLOSURE 3

WATTS BAR NUCLEAR PLANT (WBN) UNIT



CODE CASE N-597-1

CASE (continued)

N-597-1CASES OF ASME BOILER AND PRESSURE VESSEL CODE

(1) For straight pipe, bends, and elbows, tin shallbe determined by:

PD.2(S + yP)

(2) For concentric and eccentric reducers. in ateach end shall be equal to tj, of straight pipe of thesame nominal size as the reducer end. For the conicalportion of the reducer and the transition at the largediameter end, :,,.. shall be that of the large diameterend. A gradual transition in t

n shall be assumed forthe transition at the small end (see Fig. 3622-1).

(3) For branch connections and tees, except atregions providing reinforcement of the opening requiredby the Construction Code used in the evaluation, tashall be as-required for straight pipe.

(b) When t, is less than 0.9 ti,,i at any location,additional evaluations may be conducted to determinethe allowable local thickness, tce subject to the limita-tions in (c). The thinned region and the parametersthat define the depth and extent of thinning are illustratedin Fig. -3622-2. The allowable local thickness shall bedetermined in accordance with any one of the methodsin -3622.2, -3622.3, -3622.4. -3622.5, or -3622.6.

(c) Local thinning evaluation shall not be allowedfor the following:

(I) A region adjacent to any branch connectionon the run piping, unless the distance between thecenter of the branch connection and the edge of thethinned area predicted to be less than tn exceeds Ds,where D is the nominal inside diameter of the branchconnection and L, is the maximum dimension of thethinned region less than t ;n.

(2) At the small end transition of a reducer.(3) Inner portion of elbows and pipe bends (Fig.

-3622-3), excluding a region within I1. ,t,; ofthe butt welds, unless the rin m in the evaluation of-3622.2, -3622.3, or -3622.4 Is replaced by i' ,n. de-fined by:

i'At . (0-5 +I + cos,) s

-3622.2 Local Thinning- Limited TransvcrscExtent

(a) The evaluation procedure shall consider the depthand extent of the affected area and require that thewall thickness exceed r, , for a distance that is thegreater of 25 jRacmr,,mor 2Lm,, between adjacent

thinned regions, where Rnm is the mean radius of thepiping item based on nominal wall thickness and "g isthe average of the extent of L,, below ,,, for the adjacentareas (see Fg. -36224). Alternatively, the adjacentthinned regions shall be considered a single thinned regionin the evaluation.I (b) Provided that the transverse extent of wall thin-ning predicted to be less than t,.. , is less thanor equal tojR , the allowable local thickness, hav,shall be determined from Table -3622-1, wbere Rmi.is the mean radius of the piping item based on theminimum wall thickness r". For straight pipe, Table-3622-1 may be used when L,) exceeds JR_;;; i;,except that an additional thickness tb shall be addedto the value determined from Table -3622-1.

(c) This approach shall not be used to evaluate areducer.

-3622.3 Local Thinning-Limited Axial andTransverse Extent

(a) When the maximum extent of wall thinning, 4,,for which thickness is predicted to be less than tr, isless than or equal to 2.655/=,,i n,, , and t is greaterthan 1.13 t,. td, shall be determined by satisfying(b) below and (c) or (d) below. This approach requiresthat adequate reinforcement be available surroundingthe thinned area in accordance with (c) or (d). Thisevaluation approach is not applicable for the followingconditions:

(I) Thinned areas adjacent to branch connections,when. the reinforcement zone for the thinned areawould overlap the required reinforcement of the branchconnection.

(2) Thinned areas for which any portion of thereinforcement zone would lie on the conical or smalldiameter transition zone of a reducer.

(3) Adjacent thinned areas qualified by this ap-proach when the reinforcement zones associated witheach area would overlap.

(b) The thickness of the remaining pipe wall at thethinned section is adequate if the following equationis satisfied.

0.3534

(c) If there is a surrounding reinforcement zone withpredicted thickness of at least tmn for a minimum

989 SUPP. 2 - NC

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)

N-597-1CASES OF ASME BOILER AND PRESSURE *VESSEL CODE

dimension of L/2 in all directions, reinforcement forthe thinned area shall satisfy the following equation. tmi. I Cosa

to. F L ) (t-'-)

(d) As an alternative to (c), the reinforcement adjacentto the thinned area shall justify the following equation.

t.- 'a I (0.935A;nFan L,.j,,

.3622.4 Local Thinning-Unlimited TransverseExtent

(a) The evaluation shall include consideration of thedepth and extent of the affected area less than m.m*

The wall thickness shall exceed rn for an axial distancethe greater of 25 Rrntom or 2 L betweenadjacent thinned regions at each circumferential locationon the piping item (see Fig. -3622-5). Alternatively.the adjacent thinned regions shall be considered a singlethinned region in the evaluation.

(b) Thickness 'do: shall be determined from Table-3622-1.

(c) This approach shall not be used to evaluate areducer.

.3622.5 Local Thinning-Elbows and Bent Pipe

(a) For locations farther thanRmjinmoj from weldsto adjacent piping items, the predicted thickness onthe outer portion of an elbow or bend may be lessthan j. for straight pipe. The local allowable thicknessat each location shall be deternined by:

hM 2 0.5 + 0.5tS~ft I + cose

Rb(Z)where

RbM/R.~= ratio of elbow bend radius to mean piperadius, based on tr,,,, for the same size pipe

-3622.6 Local Thinning-Central Portions ofConcentric Reducers

(a) For the conical portion of concentric reducers,the loc allowable thickness less than rmiD shall satisfythe following equation:

SUPP.2 - NC

(b) For the flared transition at the small end of aconcentric reducer, the local allowable thickness shallbe gradually reduced from the value determined at theconical end of the flare to td. for the small end ofthe reducer.

(c) ibis approach shall not be used to evaluateeccentric reducers.

-3623 Piping Stress Evaluation

.3623.1 Evaluation Requirements

(a) The effects of piping stresses shall be evaluatedin accordance with the equations of the ConstructionCode used in the evaluation. If the piping designanalysis is based on nominal piping thickness, theallowable stresses used in a stress analysis based onpredicted thickness, r, (see -3210), may be multipliedby 1.143. Consideration shall be given to changes inthe pipe metal area, pipe inside area, section modulus,and stress indices or stress intensification factors, asdescribed in -3623.2, -3623.3 and -3623.4. The effectsof cyclic operating conditions shall be addressed inaccordance with -3625.

(b) The piping stress evaluation, shall be based onthe predicted thickness at. each cross section of thepiping item that exhibits significant thinning or isaffected by a change in stress index or stress intensifica-tion factor. Alternatively, the evaluation may be basedon the limiting cross section.

-3623.2 Nominal Longitudinal Pressure Stresses

(a) The pipe metal area and the pipe inside area,for the thinned cross section might result in stressesdifferent from those of the piping stress analysis ofrecord.

(b) For simplified analysis, the piping item may beassumed to be uniformly thinned with a thickness of:,.,,. For this approach, the nominal longitudinal pres-sure stress shall be determined by:

SoPD.P41.,Wn,

When evaluating reducers, the large and small endsshall be evaluated separately. For the large end, tpmnishall be determined from all locations for the largeend and conical section. For the small end, !,,, forthe entire reducer shall be used.

990

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CODE CASE N-597-1

CASE (continued)

N-597CASES OF ASMtE JOI ED AND PRESSURE VESSEL CODE

(c) Detailed stress analysis may be conducted basedon the complete set of measurements around the thinnedcross-section of the piping item. The nominal longitudi-nal pressure stress, S, shall be determined by:

PA;Ap,

(1) To evaluate piping at a branch connectionbeyond the limits of reinforcement, it shall be assumedthat the entire region within limits of reinforcement Isat thickness tin for the unreinforced pipe section, withthe outside surface at the pipe nominal outside radius.If excess reinforcement is available within the limitsof reinforcement, the excess metal area may be includedin A.,.

(2) When evaluating the longitudinal pressurestress in the central cone of a reducer, the stress shallbe determined based on the local radius at the crosssection and the local t, at and adjacent to the crosssection of interest, except that the resulting stress shallbe multiplied by a factor of I/cosa.

(d) Vben using Code Editions and Addenda thatrequire use of stress indices, the nominal longitudinalstress determined in accordance with (b) and (c) shallbe doubled.

-3623.3 Nominal Longitudinal Bending Stresses

(a) Thinning of the piping item cross-sectional areamight result in bending stresses different from thoseof the piping stress analysis of record. The nominallongitudinal bending stress, Sb, for the various loadingconditions and load combinations shall be deter-mined by:

iAli + PAsss2 a ,

(c) Detailed stress analysis may be conducted basedon a complete set of measurements around the thinnedcross section of the piping item.

(d) When evaluating thinning at the cross section ofa branch connection, the requirements of -3623.2(c)(1)shall be meL

-3623.4 Stress Intensification Factors and StressIndices

The local piping item wall thickness could affectthe stress indices or stress intensification factors usedin determination of the effective piping stress at abranch connection. When reduced wall thickness couldincrease these factors, the effect shall be consideredby using a reduced piping item thickness detenninedin accordance with (a), (b), or (c).

(a) Except as allowed in b) or (c), stress intensifica-tion factors or stress indices for a piping item shallbe based on the assumption of uniform wall thickness,using a value of t,,, and an associated mean piperadius in the formula for these factors.

(b) As an alternative (a) above, the factors may bebased on the average t, of the piping item excludingbranch reinforcement zones, except that predicted thick-ness at locations within a distance of twice the pipenominal all thickness from butt welds to adjacentcomponents need not be considered. For reducers, theaverage :,, of the small end shall be used with thesmall end diameter to determine the factor.

(c) As an alternative to (a) or (b) above, stressanalysis of thinned piping items may be conducted toshow the effects of wall thinning and the distributionof stresses on an affected piping item.

-3624 Evaluation of Branch Connections

-3624.1 The region of branch connections and teeswithin limits of reinforcement of the Construction Codeused in the evaluation shall be evaluated in accordancewith -3624.2 or -3624.3.

-3624.2 Branch Connections Not RequiringReinforcement

(a) The region on the piping run shall be evaluatedin accordance with the requirements of -3622 and -3623,without consideration of the branch connection, exceptthat tr, within a region of radius of Di of the branchpipe from the center of the branch connection shallnot be less than rj. for the pipe run.

(b) The branch piping shall be evaluated in accord-ance with the requirements of -3622 and -3623.

(b) For simplified analysis, the piping item sectionmodulus may be based on a uniformly thinned sectionwith thickness t When evaluating reducers, thelarge and small ends shall be evaluated separately. Forthe large end, r,,, shall be determined from all locationsfor the large end and conical section. For the smallend, ,,,,, for the entire reducer shall b used.

991

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)


-36243 Branch Connections RequiringReinforcement

(a) Branch reinforcement requirements shall be deter-mined in accordance with the Construction Code usedin the evaluation.

(b) For the region of the piping run that providesbranch reinforcement, the value of t, at any locationshall not be less than t, for the nominal pipe runplus any required reinforcement at that location.

(c) For the region of the branch pipe that providesbranch reinforcement, t shall not be less than tsu forthe branch pipe plus any required reinforcement

.3625 Evaluation for Cyclic Operation

(a) For piping items with t not less than 0.75tw and subject to no more than 150 equivalent fulltemperature cycles at the time of the next examination.in accordance with the Construction Code used in theevaluation,piping stress equations that include thermalexpansion and anchor movement stresses need not beevaluated.

(b) For piping items not meeting the requirementsof -3625(a), when the design includes consideration ofthermal expansion stresses, the allowable stress rangefor expansion stress shall be determined in accordancewith the Construction Code used in the evaluation,except that the stress intensification factor, 1. shall berevised to take into account the geometry of the thinnedregion. As an alternative to establishing a revised stressIntensification factor, the stress range reduction factorsof Table -3625-1. which are based on an increase inthe stress intensification factor by a factor of 2 overthe life of the component, may be'used.

(c) The potential for local overstrain in the thinnedregion for the combination of maximum sustained plusthermal expansion stresses shall be considered. Sus-tained loads include pressure, weight, and other sus-tained mechanical loads. Local overstrain is definedin NC-3672.6(b). Evaluation methods and acceptancecriteria shall be specified by the Owner.

-3626 Nomenclature

A.=total cross-sectional area of pipe based on

nominal outside diamDeter, f , in24,-

Ai=predicted inside cross-sectional area for apipe that has experienced wall thinning, in.2

A.=predicted metal cross-sectional area for apipe that has experienced wall thinning, in?

A,=predicted metal cross-sectional area ofpipe, in.2

A,,t,=the reinforcement area available in the pipewall based on the predicted thickness distri-bution in excess of rmia and within the limitsof reinforcement of the Construction Codefor an opening ith diameter ,, at theregion of local thinning, in

D.=nominal outside diameter of piping item(e.g., 10.75 for NPS 10 pipe), in.

d,=maximum outside diameter of a reducer at.the thinned location, in.

DAoutside diameter at the large end of thereducer, in.

Di= nominal inside diameter of a branch connec-tion, in.

f=stress range reduction factori=stress intensification factor of tie Construc-

tion Code (not less than 1.0)I Unpredicted minimum moment of inertia of

the thinned pipe about the neutral axis ofthe pipe section, considering all orientationsof the section neutral axis, in!

L=maximum extent of a local thinned areawith wall thickness less than t,,,, in.

L,,=maximum extent of a local thinned areawith wall thickness less than :,,, in.

4,(,)=maxinum axial extent of a local thinnedarea with wall thickness less than tmi in.

L,,,,,=maximum of the axial extents of two adja-cent local thinned areas with wall thicknessless than ,,,,, in.

L,( )=maximum transverse extent of a localthinned area with wall thickness less thant:,,, in.

L,,,,=average of the extents of thickness less thanI,,,a for two adjacent thinned areas, in.

Mfb=resulting bending moment from the designanalysis of record for each loading conditionunder consideration, in-lb

P=design pressure, psiRb =bend radius of an elbow to the elbow center

line, in.R.=nominal outside radius (e.g., 2.25 for NPS

4 pipe), in.Rm',=radius to the nominal outside surface of the

pipe plus the nominal distance between thecenter of the pipe and the neutral axis. in.

Rmii=mean radius of piping item based on thenominal outside radius and the minimum

992

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)

N-597-1CASES OF ASMIE BOILER AND PRESSUF.E VESSEL CODE

Large endtransition zone

Central conical/ section

Small endtransition zone

GENERAL NOTE:Transition zones extend from the point on the ends where the diameter begins to changeto the point on the central cone where the cone angle Is constant.

FIG.-3622-1 ZONES OF REDUCER

wall thickness (e.g., 7.85 for NPS 16 pipewith trw = 0.30 in.), in.

R,,om=mean radius of piping item based on thenominal radius and thickness (e.g., 6.75 forNPS 14 XS pipe with t, = 0.5 in.), In.

3=allowable stress-for piping item, includingjoint efficiency factor. E, if applicable, psi.

St = maximum nominal bending stress at thethinned section, psi.

S,-nominal longitudinal pressure stress, psi.t,,,,=allowable local thickness, in.

tb=uniform. thickness, of piping item, requiredby the Construction Code, to withstand sus-tAined and occasional bending loadings inthe absence of pressure, thermal expansion,and anchor movement loadings, in.

:,= inimum wall thickness required by theConstruction Code to sustain pressure, ex-clusive of-tolerances and any allowancesfor corrosion, in.

auenl= tmin for. large end of a reducer, in.rmmi ip,=tmmn for straight pipe, in.

(,radusted inimum thickness for inner por-tion of an elbow, in.

,, = nominal thickness of pipe or fitting specifiedin the applicable industry standard for the

piping item. For items designed to specifiedminimum thickness, the nominal thicknessis the design thickness, including corrosionallowance and excluding tolerances, in.

r=distribution of predicted local thickness ofa piping item at the next scheduled examina-tion, in.

t.pW.=minimum predicted local thickness of apiping item at the next scheduled examina-tion, in.

y=factor required by the Construction Codeused in the evaluation

Z^1.=predicted minimum section modulus for thethinned section, including consideration ofthe shift of the neutral axis of the thinnedpipe section, ID/R,, in?

a=maximum cone angle at the center of areducer, degree

8= maximum angle from the center of the outerone-half of the elbow to the location of thethinned area being evaluated, as measuredin the pipe cross section, degree

£=nominal distance between the cente of thepipe and the neutral axis of the thinnedpiping section, in.

993 SUPP. 2 - NC

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)

N-597-1CASES OF ASME BOLER AND PRESSURE VESSEL CODE

tnom

t V///// ~~~~I

Axiul direction

t TransverseI (hoop direction)

FIG. -3622-2 ILLUSTRATION OF WALL THINNING

SUPP. 2 - NC 994

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued

N-597CASES OF ASME DOELER AND PRESSURE VESSEL CODE

diameter

FIG. -3622-3 ELBOW AND NOMENCLATURE

995

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ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)

N-597CASES OF ASME BOMER AND PRESSURE VESSEL CODE

t 2 6inin surrounding arqa

x1.3

Area 3ro 3 < rmrnn

X- - minimum distance between areas iand JLm, - maximum extent of thinned areai

Lm,avg - 05 Lm.I + Lm

GENERAL NOTE:Combination of adjacent areas into an equivalent single area shall be based on dimensionsand extents prior to combination.

FIG. -3622-4 SEPARATION REQUIREMENTS FOR ADJACENT THINNED AREAS

996

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ENCLOSURE 3

WATTS BAR NUCLEAR PLANT (WBN) UNITFIRST 10-YEAR INTERVAL


CODE CASE N-597-1

CASE (continued

N-591CASES OF ASME BoILER AND PRESSURE VESEL CODE

4

[Note (1)]

X = minimum distanea between areas iandjat any circumferential location on pipeLmps)I . maximum extent of thinned area in axial direction

ma - maximurn of the extents Lmga and Lmal /of two adjacent areas

NOTES:II) Areas need not be combined Into single areas based on separation in the transverse direction, provided that

transverse extents of individual adjacent thinned areas do not overlap.121 Combination of adjacent areas into an equivalent single area shall be based on dimensions and extents prior to

any combination of adjarent areas.

FIG. -3622.5 SEPARATION REQUIREMENTS FOR ADJACENT THINNED AREAS

997

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ENCLOSURE 3




CODE CASE N-597-1

CASE (continued)


TABLE -3622-1

Allowable Local Tickness

-3622.2 -3622.4

O 0.100 0.1000.20 0.100 0.2610.23 0.100 0.3000.26 0.100 0.37503z 0.100 0.477

0.38 0.100 0.551OA5 0.100 0.6160.50 0.100 0.6510.60 0.100 0.7030.70 0.182 0.742

0.83 0.300 0.7780.85 0.315 0.7820.90 0.349 0.7941.00 0.410 0.8131.20 0.505 0.841

1.40 0.572 0.8601.60 0.622 0.8731.80 0.659 0.8832.00 0.687 0.8912.25 0.714 0.897

2.50 0.734 0.9002.75 0.750 0.9003.00 0.7.63 , 0.9003.50 0.787 0.9004.00 0.811 0.900

4.50 0.634 0.9005.00 0.858 0.9005.50 0.882 0.9006.00 0.900 0.900

>6.00 0.900 0.900

GENERAL NOTE:Interpolation may be used for intermediate valLes.

998

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V

ENCLOSURE 3



CODE CASE N-597-1

CASE (continued)


TABLE -3625-1MODIFIED STRESS RANGE REDUCTION FACTORS

Number of Equivalent Stress RangeFull Reduction Factor 2, f

Temperature Cycles1 , N

650 or less 1.0>650 to 1100 0.9

>I100 to 20CO 0. >2000 to 3900 0.7>3900 to 3500 0.6

>8500 to 21,000 0.5over 21,000 0.4

NOTES:(1) Cycles to next Scheduled Inspection or repair/replaccment activlty.(2) The nodified stress range reduction factors are based on an

Increase I the stress intensification factor, I by a factor of zover the lfe cf the component.

999

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ENCLOSURE 4



COMMITMENT LIST

ENCLOSURE 4



COMMITMENT LIST

1. During the Cycle 6 refueling outage, Watts Bar willultrasonically examine Grid 103BE252 elbow to steamgenerator Loop 2 inlet nozzle to obtain a new set of UTdata, obtain a refined wear rate and perform a new analysis.

E4-1

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