ML18037A983

Forwards Requests for Relief ISI-16,applicable to BFN Units 1 & 3 & ISI-2-5,applicable to BFN Unit 2.Requests for Relief Pertain to Longitudinal Weld Insps in Class 1 & 2 Piping. Requests Use of ASME Code Case N-524 for Plant ISI Programs

ML18037A983
Person / Time
Site:	Browns Ferry
Issue date:	07/06/1994
From:	Salas P TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9407140143
Download: ML18037A983 (14)

Text

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'CELERATED RIDS PROCESSING)

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9407140143 DOC.DATE: 94/07/06 NOTARIZED: NO DOCKET FACIL:50-259 Browns Ferry Nuclear Power Station, Unit 1, Tennessee 05000259 50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 P AUTH. NAME AUTHOR AFFILIATION SALAS,P. Tennessee Valley Authority RECI P . NAME RECIPIENT AFFILIATION R Document Control Branch (Document Control Desk)

SUBJECT:

Forwards Requests for Relief ISI-16,applicable to BFN Units 1 & 3 & ISI-2-5,applicable to BFN Unit 2.Requests for relief 0 pertain to longitudinal weld insps in Class 1 & 2 piping.

DISTRIBUTION CODE: A047D COPIES RECEIVED:LTR j Requests use of ASME Code Case N-524 for plant ISI programs.

ENCL TITLE: OR Submittal: Inservice/Testing/Relief from ASM'ode GL-89-04 NOTES L SIZE: C RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-4 1 0 PD2-4-PD 1 ~ 1 TRIMBLE,D 2 2 WILLIAMS,J. 2 2 INTERNAL: ACRS NRR/DE/EMEB 6

1 6

1 AEOD/DS P/ROAB NRR/EMCB 1,

1 1

1 NUDOCS-ABSTRACT 1 1 OC G 1 0 OGC/HDS3 1 0 REG FI 01 1 1 RES/DSIR/EIB 1 1 D

EXTERNAL EG&G BROWN I B 1 1 EG&G RANSOME,C 1 1 NRC PDR 1 1 NSIC 1 1 K 0 C

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NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACTTHE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2083 ) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 24 ENCL 21

0 Tennessee Valley Authority. Post Office Box 2000, Oecatur, Alabama 35609 July 6, 1994 10 CFR 50. 55a (a) (3)

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of ) Docket No. 50-259 Tennessee Valley Authority ) 50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) I UN TS 1 r 2 r AND 3 AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) SECTION XI INSERVICE INSPECTION (ZSZ) PROGRAM REQUEST FOR RELIEF CLASS 1 AND 2 PIPING LONGITUDINAL WELD INSPECTION In accordance with 10 CFR 50.4 and 10 CFR 50.55a(a)(3), TVA is submitting Requests for Relief from ASME Section XI, ISI requirements for NRC review and approval. The Requests for Relief pertain to longitudinal weld inspections in ClassN-524 1 and 2 piping. TVA is requesting to use ASME Code Case for the BFN Units 1, 2, and 3 ISI programs.

The ASME Code Committee approved Code Case N-524, "Alternative Examination Requirements for Longitudinal Welds in Class 1 and 2 Piping Section XI, Division 1," on August 9, 1993. Code Case N-524 has not been approved for use by NRC in Regulatory Guide 1.147, "Inservice Inspection 1."

Code Case Acceptability ASME Section XI, Division However, provisions stated in footnote six to 10 CFR 50.55a provide for use of other Code Cases upon request, if approved by the Director of the Office of Nuclear Reactor Regulation pursuant to 10 CFR 50.55a(a)(3).

BFN Units 1 and 3 are in their first ISI interval ASME Section XI, 1974 Edition, Summer 1975 Addenda. BFN Unit 2 is currently in it's second ISI Interval ASME Section XI, 1986 ZLJ(3tjg, 5 9407140143 05000259 94070b PDR ADOCK Q

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U:S. Nuclear Regulatory Commission Page 2 July 6, 1994 Edition. The enclosure to this letter provides Requests for Relief ISI-16, applicable to BFN Units 1 and 3, and ISI-2-5 that applies to BFN Unit 2.

The ASME Section XI Code (applicable BFN editions) currently requires one pipe diameter in length but not more than 12 inches be examined for Class 1 longitudinal piping welds.

For BFN Unit 2, Class 2 longitudinal piping welds are"t" required to be examined for a length of 2.5t, where is the thickness of the weld. These lengths of weld are measured from the intersection of the circumferential weld and longitudinal weld. For BFN Units 1 and 3, Class 2 longitudinal piping welds, are required to be examined for their full length. ASME Code Case N-524 significantly reduces the required weld examination volume and/or surface area. This is accomplished by limiting the examination of the longitudinal weld to the volume and/or surface area contained within the examination requirements of the intersecting circumferential weld. This would include, for Unit 2, the weld and one-half inch on both sides of the weld crown for surface examinations, and one-fourth inch on both sides of the weld crown for volumetric examinations (lower one-third). The weld examination volume for Units 1 and 3 would be the weld plus one-half inch or the thickness of the pipe wall (which ever is greater) on either side of the weld.

Code Case N-524 directs the weld examination at the high risk area associated with the longitudinal and circumferential weld intersections. Itexamination, eliminates low risk areas on the significantly reducing longitudinal weld from examination time requirements and radiological exposure to examination personnel. Compliance with the existing ASME Section XI requirements results in unnecessary radiological exposure to plant personnel performing the examinations without a compensating increase in the level of quality or safety.

TVA requests NRC review of the enclosed Requests for Relief as a Priority 2 High Priority Near-term item as described in a memorandum from Dr. T. E. Murley to the NRR staff, dated June 6, 1993. TVA has evaluated the potential cost savings for using ASME Code Case N-524 for BFN Units 2 and 3.

Considering weld preparation, examination, craft support, and radiological exposure costs; TVA estimates that $ 800,000 could be saved during the remaining life of the two units.

In addition, the proposed Requests for Relief could

U:S. Nuclear Regulatory Commission Page 3

.July 6, 1994 significantly reduce the duration of refueling outages. This would increase power generation revenue and save the cost incurred for the purchase of replacement power.

TVA requests NRC review and approval of the Requests for Relief by September 1, 1994. This date is necessary to support resource planning and allocation for the Unit 2 Cycle 7 refueling outage scheduled to begin on October 1, 1994.

There are no commitments contained in this letter. If you have any questions, please telephone me at (205) 729-2636.

Sincerely, as Manager of Site Licensing Enclosures cc (Enclosure):

Mr. Mark S. Lesser, Section Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. D. C. Trimble, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

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ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 1, 2, AND 3 AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) SECTION XI INSERVICE INSPECTION (ISI) PROGRAM REQUESTS FOR RELIEF (SEE ATTACHED)

ISI-2-5 UNIT 2 ISI-16 UNITS 1 AND 3

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R es F r Relief ISI-2-5 (Unit 2)

Com onents: Longitudinal Welds in Class 1 and 2 Piping Classification: Class 1 and 2 Code Cate pries: B-J, C-F-1, and C-F-2 Item Numbers: B9 ~ 1 2 I B9 22 g C5 12 / C5 ~ 22 g C5 ~ 42 g C5 ~ 521 C5 ~ 62 and C5.82 Ins ection Re uirements: ASME Section XI, 1986 Edition, Table IWB-2500-1 requires a volumetric and/or surface examination be performed of at least one pipe diameter length but no more than 12 inches of each longitudinal weld that intersects a circumferential weld required to be examined under Code Category B-J.

ASME Section XI, 1986 Edition, Table IWC-2500-1 requires a volumetric and/or surface examination to be performed of at least 2.5t, where "t" is the thickness of each longitudinal weld that intersects a circumferential weld requiredC-F-2. to be examined under Code Categories C-F-1 and Basis For Relief: Longitudinal piping welds are fabricated during the manufacturing process under controlled shop conditions, which produce higher quality welds and more uniform residual stress patterns.

Longitudinal piping welds undergo heat tzeatment in the manufacturing facility, which enhances the material properties of the weld and reduces the residual stress created by welding.

Results of previous weld inspections throughout the industry indicate that longitudinal welds have not been a safety concern, and there has been no evidence of longitudinal weld defects compromising safety at nuclear power plants.

Longitudinal welds have not been shown to be susceptible to any particular degradation mechanism.

The only areas of a longitudinal weld that may be suspect are the ends of the weld adjacent to the field fabricated circumferential weld.

Longitudinal welds are extremely difficult to locate even when the piping is identified as welded pipe. Typically, the existence and location of longitudinal welds must be determined by acid etching, eddy current examination, or a combination of the two methods. This results in an increase in personnel radiological exposure and generation of radwaste above that incurred as a result of performing the required examinations of the longitudinal welds.

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Re ues F r Relief ISI-2-5 Basis For Relief (cont.): The radiological exposure and cost associated with the inspection of longitudinal welds are dependent on the time it would take to remove and reinstall insulation and interferences, prepare the weld for examination, and perform the examination.

Based on the above, the inspection of longitudinal welds as currently required by ASME,Section XI is not technically warranted.

The ASME Code Committee has recognized this fact and has published Code Case N-524, "Alternative Examination Requirements For Longitudinal Welds In Class 1 and 2 Piping Section XI, Division 1."

Alternate Ins ection: As an alternative to the existing ASME,Section XI requirements, Browns Ferry Nuclear Plant will adopt the provisions of ASME Code Case N-524 for the examination of Class 1 and 2 longitudinal piping welds.

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R ue F r Relief ISI-16 (Units 1 and 3)

~Com onents: Longitudinal Welds in Class 1 and 2 Piping Classification: Class 1 and 2 Code Cate pries: B-J, C-F, and C-G Item Numbers: B4.5 and C2.2 Ins ection Re uirements: ASME Section XI, 1974 Edition, Summer 1975 Addenda, Tables IWB-2500 and IWB-2600 require a volumetric examination to be performed of at least one pipe diameter length but no more than 12 inches of each longitudinal weld that intersects a circumferential weld required to be examined under Code Category B-J.

ASME Section XI, 1974 Edition, Summer 1975 Addenda, Tables IWC-2520 and IWC-2600 require a volumetric examination to be performed for the total length of a longitudinal weld selected for examination in accordance with Code Categories C-F and C-G.

Basis For Relief: Longitudinal piping welds are fabricated during the manufacturing process under controlled shop conditions, which produce higher quality welds and more uniform residual stress patterns.

Longitudinal piping welds undergo heat treatment in the manufacturing facility, which enhances the material properties of the weld and reduces the residual stress created by welding.

Results of previous weld inspections throughout the industry indicate that longitudinal welds have not been a safety concern, and there has been no evidence of longitudinal weld defects compromising safety at nuclear power plants.

Longitudinal welds have not been shown to be susceptible to any particular degradation mechanism.

The only areas of a longitudinal weld that may be suspect are the ends of the weld adjacent to the field fabricated circumferential weld.

Longitudinal welds are extremely difficult to locate even when the piping is identified as welded pipe. Typically, the existence and location of longitudinal welds must be determined by acid etching, eddy current examination, or a combination of the two methods. This results in an increase in personnel radiological exposure and generation of radwaste above that incurred as a result of performing the required examinations of the longitudinal welds.

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~ +~ ~ dt Re ues For Reiief ISI-16 Basis For Relief (cont.): The radiological exposure and cost associated with the inspection of longitudinal welds is dependent on the time it would take to remove and reinstall insulation and interferences, prepare the weld for examination, and perform the examination.

Based on the above, the inspection of longitudinal welds as currently required by ASME,Section XI is not technically warranted.

The ASME Code Committee has recognized this fact and has published Code Case N-524, "Alternative Examination Requirements For Longitudinal Welds In Class 1 and 2 Piping Section XI, Division 1."

Alternate Ins ection: As an alternative to the existing ASME,Section XI requirements, Bzowns Ferry Nuclear Plant will adopt the provisions of ASME Code Case N-524 for the examination of Class 1 and 2 longitudinal piping welds.

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