ML20206B714

Requests Exemption from Requirements of ASME Boiler & Pressure Vessel Code,Section Xi.Fee Paid

ML20206B714
Person / Time
Site:	Brunswick
Issue date:	11/04/1988
From:	Mcduffie M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NLS-88-204, NUDOCS 8811150551
Download: ML20206B714 (6)

Text

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gg Carolina Power & l.lght Company W4 g SERIAL: NLS-88-204 10CFR50.33a United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20333 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 30-324/ LICENSE NO. DPR-62 ASME CODE RELIEF REQUEST - SERVICE WATE' RR-09 Gentlemen:

Carolina Power & Light Company (CP&L) hereby requests an exemption from the requiremer.ts of the ASME Boiler and Pressure \\ essel Code,Section XI, for the Brunswick Steam Electric Plant, U.ilt 2 (BSEP-2). The provisions of 10CFR50.53a(aX3) allow for exemptior.s when compliance with the rpacified requirements would result in hardship or unusual ditficulties without a compensating increas: in the level of quality and safety.

BACKGROUND During BSEP-2 operation on July 3,1988, a through-vw. leak was discovered in a weld in the servlee water system (see Attachments I and 2). The line is located downstream of the 2-Ell-PDV-F068B control valve and is the B-loop service water discharge header.

The through-wall failure is located in weld FWl3 of the lin e number 2-SW-173-20-137 in the Unit 2 reactor building.

An ultrasonic thickness mapping was perfermed on this weld and six similar w elds on the A and B service water loops for both BSEP units. The ultrasonic testing ruealed fouc L

Indications in field weld FW13. Three of the four indications ia weld FWl3 were relatively small and of little consequence. The fourth indication was identified as being 11.5 inches in length and 66% through-wall in the area of the through-wall leak.

Ultrasonic testing of the similar welds on both BSEP units revealed several minor indications comparable to those found in weld FW13, i.e., they were small and of little consequence.

The line in which the indication is located is classified as Seismic Class and ASME ISI Class 3. A temporary repair was performed which consisted of a carbon steel split collar r

being fully welded to the service water piping, top and bottom,360 degrees by means of a fillet weld and the halves of the collar longitudinally welded on both sides with a full penetration weld (see Attachment 3). Code repair or repleement would have necessitated unit shutdown for implementation. A Justification for Continued Operation (JCO) was prepared and approved by the Plant Nuclear Safety Committee

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f [0 (PNSC). The design calculations performed verified that full structural and seismic l

g integrity of the l'.ne would be maintained by the repair.

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,.NSL-8$-204 / P:g2 2 Due to the operating cc figuration, an isolable hydrostatic test boundary could not be achieved during unit operation. Thus, the hydrostatic test required by IWA-4400(a) was not performed immediately af ter the repair.

REQUIREMENT The ASME Boiler and Pressure Vessel Code,Section XI,1980 Edition through the Winter 1981 Addenda, Article IWA-4000 describes the requirements for repair of pressure-retaining components. IWA-4120 states that repairs shall be performed in accordance with the Owner's Dealgn Specification and Construction Code. IWA-4400 requires that a hydrostatic test be performed af ter a repair is made.

JUSTIFICATION The impact of the small indications identified by the ultrasonic tests is insignificant since they are radially separated and appear sha'llow, $ ort, and do not %trude into the design minimum wall thickness requirement. The ultrasonic test resul.; for the through-wall indication show that its maximum depth, determined at the area of the through-wall failure, is approximately 66% through-wall. The indication extends 11.5 inches in length along the weld. A stress anal sis was performed assuming there was 11.5 inches of through-wall indication along weld int FWl3. The normal operating stress in this piping system is approximately.50% i the total design stress. The total desi n stress is approximately U% of the material maximum code allowable stress. The anal sis indicated that structural integrity of the piping system would have been mai tained during a design basis earthquake.

A JCO was prepared and approved by the PNSC. The basis for the JCO was an evaluation / calculation which confirmed that the subject piping was operable considering operation stresset only. A Probablistic Risk AssessmentIPRA) concluded that risk of a design basis seismic event was acceptable until a temporary / calculation later concludedrepair could b within a given time restriction. Finalization of the analysis that the piping system was Short Term Seismically Qualified with the through-wall indication.

affected weld. g" { of the piping has been ensured b addingad to the pipe. Design The seismic inte it a band of metal around the "is a split collar which was fu ly wel calculations verif.

A.t full structural and seismic integrity of the line would be maintained by the <. 'poray repair.

The hydrostatic test required b/ IWA-4400 was not performed due to the operating configuration of the system. An isolable hydrostatic test boundary could not be achieved during unit operation. The alternate tests performed ensure piping integrity because plant experience has demonstrated that the actual system pressure in the area of the weld ranges from little more than static head resulting from discharge weir anti-siphon level to near vacuum immediately below the control valve 2-E11-PDV-F06SB. The piping design pressure is 150 psig.

/tLTERNATE TESTING i

A system inservice pressure test was performed in accordance with paragraph IWA-5213(c).

A monthlv visual in:pection will be performed on the temporary repair until the service water piping is raplaced during the next BSEP-2 refueling outage currently scheduled to begin in August '.989.

GENERAL The events described above are discussed in Inspection Report Nos. 50-325/324/88-26. As a result of the inspection, CP&L committed to revise plant procedures to raquire NRC approval prior to deviation from the ASME Code. Based on further evaluation and discussion with members of the NRC Staf f, the Company will incorporate the following process into plant procedures for obtaining NRC approval of ASME Code relici requests.

Docunient Control Desk NSL-88-204 / Page 3 If plant operating conditions do not permit obtaining prior NRC approval of variances from the ASME Code (i.e., during holidays, weekends, and when immediate repairs are required), then:

The plant staf f will implement any immediate actions that may be deemed necessary to ensure the continued safe operation of the facility.

The plait staf f will attempt to notify the NRC as quickly as possible (either through the NRC Resident inspector, Regio. II, and/or through Corporate Licensing and the NRR Project ManagerTof the situation.

Within ten working days of occurrence of the situation, the Company will submit for NRC review and approval an ASME Code relief request. The Code relief request will solicit prompt NRC issuance of interim relief until such time as final approval of the relief request can be issued (if approved).

Otherwise, the Company will continue to seek NRC approval prior to deviating from the ASME Code ADMINISTRATIVE Carolina Power & Light Company has reviewed this request in accordance with 10CFR170.12 and determined that an application fee is required. A check for $130 is enclosed in payment of this fee.

Please refer any questions regarding this submittal to Mr. Stephen D. Floyd at (919) 836-6901.

Yours very truly, d74'O

"/T M. A. McDuf fie Senior Vice Preside..

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