ML20217D205

SER Authorizing Licensee to Use Code Case N-524 Until Such Time as Code Case Included in Future Rev of RG 1.147

ML20217D205
Person / Time
Site:	Perry
Issue date:	04/20/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20217D194	List: ML20217D191 ML20217D205
References
RTR-REGGD-01.147, RTR-REGGD-1.147 NUDOCS 9804240242
Download: ML20217D205 (5)

Text

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Q M2 O" i UNITED STATES

{ j NUCLEAR RE2ULATORY COMMISSION WASHINGTON, D.C. 20066 4 001

. . . . . ,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ASME CODE CASE N-524 PERRY NUCLEAR POWER PLANT. UNIT NO.1

, CENTERIOR SERVICE COMP &liY DOCKET NO: 5048,0.

1.0 INTRODUCTION

The Technical Specifications for the Perry Nuclear Power Plant, Unit 1, state that the inservice inspection and testing of the American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable addenda as required by 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).

10 CFR 50.55a(a)(3) states that a!(ematives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed altematives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) on the date 12 months prior to the start of the 120-month interval, subject to the limitations and rnodifications listed therein. The anplicable edition of Section Xi of the ASME Code for the Perry Nuclear Power Plant, Unit 1, during the first 10-year inservice inspection (ISI) intervalis the 1983 Edition through the Summer 1983 Addenda. The components (including supports) may meet the requirements set farth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval.

Pursuant to 10 CFR 50.55a(g)(5), if the licensee determ!nes that conformance with an examination requirement of Section XI of the ASME Code is not practical for its facility, information shall be submitted to the Commission in support of that determination and a request roade for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Comminion may grant relief and may impose ENCLOSURE 9804240242 980420 PDR ADOCF. 05000440 P PDR

1 alternative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.

By letter dated December 18,1997, Centerior Service Company, the licensee, requested approval for the implementation of the altemative criteria of ASME Sedion XI Code Case N-524 dated August 9,1993, titled " Alternative Examination Requirements for Longitudinal Welds in Class 1 and 2 Piping,Section XI, Division 1", pursuant to 10CFR 50.55a(a)(3) to be applied to the first 10-year inservice inspection interval of Perry, Unit 1.

The staff has reviewed and evaluated the licensee's request and the supporting information to use Code Case N-524 as a proposed attemative to the ASME Code requirements for the Perry Nuclear Power Plant Unit 1.

2.0 DISCUSSION HIS FOR LONGITUDINAL WELDS IN CLASS 1 AND 2 PIPING - SECTION XI. DIVISION 1 1 Comoonent identificallDB r

Class 1, Category B-J and Class 2, Categories C-F-1 and C-F-2, longitudinal piping welds (examination items B9.12, B9.22, C5.12, C5.22 and C5.42).

Code Reouirement:

ASME Class 1 longitudinal seam welds require examination of one pipe diameter in length, but no more than 12 inches of each longitudinal wald intersecting the circumferential welds. ASME Class 2 longitudinal seam welds require examination of 2.5t (where t is the thickness of the weld) in length at the intersecting circumfemntial weld. The weld length is measured from the intersection of the circumferential weld and longitudinal weld.

Code Reauirement From Which Relief is Reauested:

Relief is requested from performing the Code required examination of Class 1 and 2 longitudinal piping seam welds for the lengths identified above.

Basis for Relief (as stated by the bcensee)

"The structural integrity of the longitudinal welds Ivas demonstrated during construction by meeting the requirements of the ASME Code Section Ill, and additionally, by meeting the requirements of ASME Section XI during preservice examination. Furthermore, through Perry's fifth refueling outage, all inservice examinations of longitudinal welds were performed to the full extent required.

There were no reportable indications during the preservice or inservice examinations.

l l Industry experience in performing inservice examinations of safety class piping has demonstrated that in-service flaws are not being found in longitudinal welds.

This prompted ASME Subcommittee XI to write Code Case N-524. The conclusion of ASME Subcommittee XI was that examination of longitudinal seams beyond their intersection with a circumferential weld provides little or no benefit and, therefore, the extent of examination could be limited to the intersecting portion of the longitudinal seam without compromising the level of quality and safety.

Examination of longitudinal welds beyond their intersection with the circumferential weld involves the removal of additional insulation and, in some cases, the removal of hanger clamps or other appurtenances. It is estimated

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that these activities are cause for at least 2 REM of exposure to workers each refueling outage. Thus, compliance with the specific requirements results in hardships without a compensating increase in the level of quality and safety.

Although Code Case N-524 is not included in Revision 11 of Regulatory Guide 1.147," Inservice inspection Code Case Acceptibility- ASME Section XI Division 1," it is listed as an accepted Code Case in DG-1050 (Revision 12 to Regulatory j Guide 1.147), which is out for public comment."

Attemative Examination (as stated bv the licenseek 4

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" Perry proposes to perform inservice examination of longitudinal welds utilizing 1 the alternative requirements delineated in Code Case N-524. In accordance with Code Case N-524, the following shall apply:

(a) When only a surface examination is required, examination of longitudinal piping welds is not required beyond those portions of the we!ds within the examination boundaries of the intersecting l circumferential welds.

(b) When both surface and volumetric examinations are required, examination of longitudinal piping welds is not required beyond those portions of the welds within the examination boundaries of the intersecting circumferential welds provided the following requirements are met.

(1) Where longitudinal welds are specified and i locations are known (as is the case within Perry's current inservice examination boundary),

examination requirements shall be met for both transverse and parallel flaws at the intersection of the welds and for that length of longitudinal weld within the circumferential weld volume; L_____._._.._______ . . _ _ . . ._...__w

i (2) Where longitudinal welds are specified and locations ,

are unknown, or the existence of longitudinal welds is uncertain, the examination requirements shall be met for both transverse and parallel flaws within the entire examination volume of intersecting circumferential welds."

3.0 EVALUATION

The ASME Section XI Code (1983 Edition) requires one pipe diameter in length, but no more than 12 inches, be examined for Class i longitudinal piping welds. Class 2 longitudinal piping  ;

welds are required to be examined for a length of 2.5t, where t is the thickness of the weld. l These lengths of weld are measured from the intersection of the circumferential weld and ,

longitudinal weld. The licensee's proposed alternative, Code Case N-524, limits the volumetric and surface examination requirements of the longitudinal weld to the volume or area contained within the examination requirements of the intersecting circumferential weld.

Longitudinal welds are produced during the manufacturing process of the piping, not in the field as is the case for circumferential welds. The Code contains requirements on characteristics and performance of materials and products, and specifies the examination requirements during the manufacturing of the subject longitudinal piping welds.

In addition, there are material, chemical, and tensile strength requirements in the Code. The ,

manufacturing process that is specified by the Code provides assurance of the structural integrity of the longitudinal welds at the time the piping is manufactured.

The preservice examination and initialinservice examinations have provided assurance of the structural integrity of the longitudinal welds. The experience in the United States has been that pipes with shop welded longitudinal seams have not experienced degradation that would warrant continued examination beyond the boundaries required to meet the circumferential weld examination requirements. No significant loading conditions or known material degradation mechanisms have become evident to date which specifically relate to longitudinal seam welds in nuclear plant piping.

If any degradation associated with a longitudinal weld were to occur, it is expected that it would be located at the intersection with a circumferential weld. This intersection is inspected in  ;

accordance with the provisions of Code Case N-524. Furthermore, the 1983 ASME Code,  !

Section XI, Appendix ill " Ultrasonic Examination of Piping Systems" which is applicable to the j subject plant, requires scanning for reflectors parallel and transverse to the weld seam in case l of ferritic piping, contrary to the requirement in some older Code editions to only scan for reflectors oriented parallel to the weld seam. The transverse scan of a circumferential weld, will l further detect reflectors oriented parallel to a longitudinal weld at the root of intersection of a longitudinal seam.

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4.0 CONCLUSION

Based on the above discussions, the staff concludes that the licensee's proposed use of Code Case N-524 as an attemative to the Code requirements, provides an acceptable level of quality and safety by providing assurance of structuralintegrity. Therefore, the licensee's proposed attemative to use Code Case N-524 is authorized for the Perry Unit 1, pursuant to 10CFR50.55a(a)(3)(i). The licensee is authorized to use Code Case N 524 until such time as ,

the code case is included in a future revision of Regulatory Guide 1.147. At that time the >

licensee is to follow al1 provisions in Code Case N-524, with limitations issued in Regulatory Guide 1,147, if any, should the licensee continue to implement this relief request.

Principal Contributor: P. Patnaik Date: April 20, 1998 l

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