ML20212D146

SER Accepting Request to Use Proposed Alternative to Certain Weld Repair Requirements in ASME Boiling & Pressure Vessel Code

ML20212D146
Person / Time
Site:	Seabrook
Issue date:	09/17/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20212D144	List: ML20212D140 ML20212D146
References
NUDOCS 9909230019
Download: ML20212D146 (3)

Text

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.eup .ft UNITED STATES j j

'f NUCLEAR REGULA ORY COMMISSION WASHINGTON, D c. 20555 4 001

. . . . . ,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATICN ALTERNATIVE TO WELD REPAIR REQUIREMENTS SEABROOK STATION. UNIT NO.1 NORTH ATLANTIC ENERGY SERVICE CORPORATION DOCKET NO. 50-443

1.0 INTRODUCTION

in a letter dated July 9,1999, North Atlantic Energy Service Corporation (the licensee),

requested relief from certain weld repair requirements in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) at Seabrook Station, Unit No.1 (Seabrook). The licensee proposed as an alternative the implementation of the requirements of Specification SA 351, Grade CD4MCu, to the 1989 Edition of Section 11 of the Code in lieu of the requirements of Table I-7.2 to the 1989 Edition of Section lll of the Code.

2.0 BACKGROUND

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including supports) must meet the requirements, except design and access provisions and preservice examination requirements, set forth in Section XI of editions of the Code and addenda that become effective subsequent to the editions specified in paragraphs (g)(2) and (g)(3) of this section and that are incorporated by reference in paragraph (b) of this section, to the extent practical within the limitations of design, geometry and materials of construction of the components.

2.1 Code Requirements The applicable edition of Section XI of the Code for Seaorook is the 1989 Edition with no addenda of the Code. Subsection IWA-4120(a) to Section XI of the Code states that " repairs shall be performed in accordance with the Owner's Design Specification and the original Construction Code of the component or system. Later editions and addenda of the Construction Code or of Section lil, either in their entirety or portions thereof, and code cases may be used." The repair of castings manufactured from SA-351, Grade CD4MCu material is required to follow Section Ill. However, note (5) to Table I-7.2 " Allowable Stress Values S for

?' :Witic Pte.M. H;gh Nickel Alloys, and Copper Alloys for Class 2 and 3 Components" to Section 111 of the Code prohibits the use of welding processes on SA-351, Grade CD4MCu material.

r-Enclosure 9909230019 990917 PDR ADOCK 05000443 P PDR

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4 2-Contrary to note (5), paragraph NCA-122i IG Section 111 of the Code states that " materials shall be manufactured to an SA, SB, or SFA specification..." and specification SA-351/SA-351M, Section 10 " Repair by Welding" to Section 11 of the Code allows weld repairs to Grade CD4MCu material, provided the repairs are made using procedures and welders qualified under Section IX of the Code.

2.2 Request for Approval of an Alternative Pursuant to 10 CFR 50.55a(a)(3) proposed alternatives to the requirements of paragraphs (c),

(d), (e), (f), (g), and (h) of this section or portions thereof may be used when authorized by the Nuclear Regulatory Commission (NRC). The applicant shall demonstrate that: (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

2.3 Proposed Alternative The licensee proposed that repairs made to components utilizing SA-351, Grade CD4MCu materials in the service water and service water cooling tower pumps will be performed using procedures and welders qualified under Section IX of the Code. Weld repairs shall be inspected to the same quality standards that are used to inspect the castings. Radiography inspections shall be used when Supplementary Requirement SS is specified, when weld repairs are made on castings that have leaked on hydrostatic test, or when castings in which the depth of any cavity prepared for welding exceeds 20 percent of the weld thickness or 1 inch [25mm],

whichever is smaller, or when castings in which any cavity prepared for welding is greater than approximately 10 inches (65 cm2 ). When castings are produced with Supplementary Requirement S6 being specified, weld repairs shall be inspected by liquid penetrate examination to the same standards that are used to inspect the castings. These requirements are consistent with the requirements in Specification SA-351/SA-351M, Section 10,

• Repair by Welding" to the 1989 Edition of Section 11 of the Code.

In addition to the above, no weld repairs will be performed on-site at Seabrook. All repairs to the SA-351, Grade CD4MCu material will be performed in accordance with a 10 CFR Appendix B quality assurance program by an ASME certificate holder at the certificate holder's facility where the material can be solution heat-treated after the weld repair. The ferrite content of the repairs will be controlled utilizing procedures and administrative controls approved by the licensee.

2.4 Basis for Request Seabrook is proposing to use an alternative to the requirements in Section lli of the Code for service water pumps to resolve a contradiction in the Code. Specif'cc"y, M.b:c'A ,;roposes to use the requirements in Section ll of the Code as an alternative.

During the manufacturing of the service water pumps, cer'tain material conditions may require that weld repairs be performed on components made from SA 351, Grade CD4MCu. Section 10 " Repair by Welding"of Specification SA-351/SA-351M to the 1989 Edition of Section 11 of the

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l Code allows weld repairs for all grades of SA 351 material provided the repairs are made using procedures and welders qualified under Section IX of the Code. Note (5) of Table l-7.2 to the l 1989 Edition of Section lli of the Code is in conflict with Section 11. Section ill requirements prohibit the use of welding processes for repairs of SA-351, Grade CD4MCu material. This conflict was resolved in the 1995 Edition of the Code by moving the data contained in earlier editions of Table I-7.2 of Section til to Table 1 A, Section ll, Part D and removing footnote (5).

The NRC published a proposed rule (62 FR 63982) dated December 3,1997, which would amend 10 CFR 50.55a to permit the use of 1989 Addenda through the 1996 Addenda of the l Code. However, the NRC has not issued the final rule.

3.0 EVALUATION The most recent Code referenced in 10 CFR 50.55a is the 1989 Edition with no addenda. The i differences between Section 11 and Section ill in the 1989 Edition of the Code have been l reso.lved in the 1995 Edition of the Code that permits weld repair providing certain conditions

[ are met.

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) The licensee will use the requirements consi. stent with Specification SA-351/SA-351M, Section 10. " Repair by Welding" to the 1989 Edition of Section 11 of the Code. Section 10 requires that repairs are made using procedures and welders qualified under Section IX of the Code.Section IX requires that procedures and welders be qualified by means of performance demonstrations. The successful demonstration of procedures and w' elder skills and verification of weld integrity with nondestructive examinations provides assurance that the weld repair has an acceptable level of quality and safety.

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4.0 CONCLUSION

l The NRC staff has reviewed and evaluated the licensee's proposed alternative to use l Section 10 " Repair by Weiding" to Specification SA-351/SA-351M of the 1989 Edition of j

! Section ll of the Code for weld repairs on Grade CD4MCu castings. Based on the above '

l discussion, the NRC staff has determined that the proposed alternative would provide an L acceptable level of quality and safety. )

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! Pursuant to .10 CFR 50.55a(a)(3)(i), the proposed alternative is authorized for repair welds on  !

Specification SA-351/SA-351M, Grade CD4MCu castings.

Principal Contributor: D. Naujock i

Date: September 17, 1999 l

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