ML20086Q854

Requests Relief from Requirements of Paragraphs IWA-7110 & IWA-7210 of Section III of ASME Code.Relief Specific for Weld Located Between 24 Inch HPCI Turbine Exhaust Line & 10 Inch Branch Line

ML20086Q854
Person / Time
Site:	Cooper
Issue date:	07/21/1995
From:	Mueller J NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NLS950144, NUDOCS 9507280217
Download: ML20086Q854 (6)

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NLS950144 l July 21,1995 g . U.S. Nuclear Regulatory Commission Attention: Document Control Desk

. Washington, D.C. 20555  ;

Subject:

Third Ten-Year Interval inservice Inspection Relief Request Iligh Pressure Coolant Injection (IIPCI) Turbine Exhaust Line Pressure Boundary Cooper Nuclear Station  !

NRC Docket No. 50-298, License No. DPR-46 ,

Reference:

1) Letter (No. NLS940084) to U.S. Nuclear Regulatory Commission Document Control Desk from Nebraska Public Power District dated -  ;

December 23,1994," Exemption Request - HPCI Turbine Exhaust Line Pressure Boundary" i Letter to G. R. Ilorn from William D. Beckner (NRC) dated' February 7, l 2) 1995, " Cooper Nuclear Station - Request for Relief from the Requirements

• of 10 CFR 50.55a: HPCI Turbine Exhaust Line Pressure Boundary (TAC '

No. M91252)"

Gentlen en: .j i

In accordance with the requirements of 10 CFR 50.55a(a)(3), the Nebraska Public Power District

. (District) requests relief from the requirements of Paragraphs IWA-7110 and IWA-7210 of the Section Ill, American Society of Mechanical Engineers Boiler and Pressure Code. Specifically, this reliefis for the weld located between a 24" high pressure coolant injection (HPCI) turbine ,

exhaust line and 10" branch line at Cooper Nuclear Station (CNS). The relief, once granted, will  !

be effective throughout the Third Ten-Year ISI interval, scheduled to commence on January 1, 1996, subject to the completion of the 1995 refueling outage. The District requests that relief be granted under both the provisions of 10 CFR 50.55a(a)(3)(i) and 10 CFR 50.55a(a)(3)(ii). The

~ justification supporting the granting of this relief under these provisions is contained in both i E Reference 1 and the attachment to this letter.  !

On December 23,1994, the District submitted a request for relief (Reference 1) on a permanent l basis from the ASME Boiler and Pressure Vessel Code,Section XI and Section til requirements.

-- On February 7,1995, the Nuclear Regulatory Commission (NRC) approved the subject relief request only through the end of the current Ten-Year Inservice Inspection (ISI) interval. The. _!

safety evaluation associated with Reference 2 stated that the District would be required to I resubmit this request for the Third Ten-Year ISI interval. In response, the District is submitting -!

. the subject relief request in the attachment to this letter. 1 9507280217 950721 1 L Of' i DR ADOCK 0500 8

U.S. Nuclear Regulatory Commission July 21,1995 Page 2 of 2 The District requests NRC approval of the subject relief request by September 1,1995. This date "

is based on the District's need to allow sufficient time to plan for the weld replacement during the 1995 refueling outage, currently scheduled to commence October 1995, should the subject relief request be denied.

If you have any questics.s or require any additional information, please contact me.

Sincerely,

/

f.11. Mueller Site Manager

/dnm cc: Regional Administrator USNRC Region IV Arlington, TX NRC Resident inspector Cooper Nuclear Station NRC NRR Project Manager Rockville, MD NPG Distribution i

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t Cooper Nuclear Power Station Third Ten Year Interval Inservice Inspection Program l

RELIEF REQUEST NUMBER: RI-01 COMPONENT IDENTIFICATION '

Code Class: 2

References:

IWA-7210(b)

Examination Category: Exempt Item Number: N/A

Description:

24" HPCI Turbine Exhaust 10" Branch Connection Component Numbers: N/A CODE REQUIREMENT IWA-7210(b) states that items to be used for replacements shall meet the requirements of the applicable Construction Code to which the originalitem was constructed and the existing design requirements. The design specification specifies ASME Section III, Subsection NC, 1974 Edition with the Summer 1977 Addenda as the Construction Code. ,

Section III, paragraph NC-4244(a) states that nozzles and branch and piping connections shall be attached by full penetration butt welds through the wall of the component.

1 BASIS FOR REIIEF The subject weld, as shown in Figure RI-01.1, was installed in 1983 by a fillet weld instead of a full penetration butt weld. The Code requirements for the fabrication and installation of branch connections insures the connection will be of adequate strength within the limits of the allowable stresses. Configurations other than those specified in the Code may be used as long i as stresses are within Code limits. CNS performed a stress analysis of the subject weld which accounted for the section properties of the weld and followed the general analysis guidelines of Subsection NC, including the appropriate stress intensification factor, branch reinforcement requirements, and loading conditions. The conclusion of this analysis is that the integrity of the weld is acceptable in its current condition. This conclusion is based on the following:

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1) Nondestructive examination (VT-1 and PT) was performed on the weld at the time of installation, and the weld was found to be free of surface flaws. -

2) The weld is not subject to secondary stress loads due to thermal expansion or anchor i movements that could result in future crack initiation and/or propagation.

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Cooper Nuclear Power Station Third Ten Year Interval Inservice Inspection Program  ;

RELIEF REQUEST NUMBER: RI-01

3) - There is adequate reinforcement provided by the 24" XS pipe such that no additional branch reinforcement is required for the attached weldolet.

4) The weld has performed satisfactorily for over twelve years of operation.

5) As shown below, the primary stresses in the weld are significantly lower than the Code allowable stresses:

f SERVICE CALCULATED CODE RATIO LEVEL WELD STRESS ALLOWABLE OF STRESSES -

STRESS A

1,386 psi 15,000 psi 0.09 B 1,771 psi 18,000 psi 0.10 C 2,120 psi 27,000 psi 0.08 D 2, 316 psi 36,000 psi 0.06 Note: 1) The calculated stresses are based on design / peak pressure and bending / torsional movement stresses. i

2) The Code allowable stresses are based on the lowest allowable stress of either of the two components associated with the weld in question.

PROPOSED ALTERNATE PROVISIONS As an alternate, the fillet weld between the 24" HPCI Turbine exhaust line and the 10" branch  ;

connection will remain inservice for the balance of the interval.

APPLICABII TIME PERIOD Relief is requested for the Third Ten Year Interval of the CNS Inservice Inspection Program.

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• Cooper Nuclear Power Station Third Ten Year Interval Inservice Inspection Program RELIEF REQUEST NUMBER: RI-01 FIGURE RI-01.1 24" HPIC TURBINE EXHAUST 10" BRANCH CONNECTION l'

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IF# WNRF RANOC .

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10*W SCH. 80 S.R. ELBO W

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_ . INSERT WELDOLET g =. . a , - ,

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LIST OF NRC COMMITMENTS l ATTACHMENT 3 l Correspondence No: NLS950144 The following table identifies those actions committed to by the District in this document. Any other actions discussed in the submittal represent intended or planned actions by the District. They are described to the NRC for the NRC's information and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITTED DATE COMMITMENT OR OUTAGE There are no new commitments contained in this N/A correspundence.

PROCEDURE NUMBER 0.42 l REVISION NUMBER 0 l PAGE 10 OF 16