ML20086H975

Forwards Temporary Request for Relief from ASME Code for Weld Leakage on Component Cooling Sys HXs OB2 & 2A1,per 911120 Telcon Re Actions Taken to Address Leakage from Two Socket Weld Joints.Supporting Calculation SCG-2M-0025 Encl

ML20086H975
Person / Time
Site:	Sequoyah
Issue date:	12/02/1991
From:	Joshua Wilson TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20086H977	List: ML20086H975 ML20086H985
References
NUDOCS 9112100219
Download: ML20086H975 (5)

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l December 2, 1991 l l

U.S. Nuclear Pegulatory Commission ATTN ~ Document Control Deak ,

'4ashington, D.C. 00555 Gentlement ,

in the Matter of ) _ Docket Nos. 50-327 t Tennessee Valley Authority ) 50-328  !

SEQUOYAH NUCLEAR PLANT-(SQN) - TEMPORARY RELIEF PROM AMERICAN SOCIETY OF MECHANICAL ENG1N"ERS ( ASME) CODE FOR '4 ELD !.EAKAGE ON COMPONENT COOLING SYSTEM  !

(CCS) HEAT EXClF 'CERS (HX'S) OB2 AND 2A1 During a Novettber *,0,1991, telephone conic.:ence call between NRC and TVA i staffs. TVA proviced additional information regarding the actions that had been takei) to address icakage from two socket weld joints (fillet weld on i sacket connection) located in ASME Code Class. 3 piping (3/4-inch piping leading to a thermal relief valve on the shell side [ essential raw cooling water]) cf the OB2 and'2A1 CCS hx's.

A secondary purpose of-the telephone conference call was to'obtain clarification of NRC ataf f's position regardin regulatory actions that must be taker. to address the socket weld leakage. NRC stati indicated in the telephone conference call that the following actions were required Perform an engineering analysis by the next day to determine if the temporary clamp, which was installed to limit weld leakage, would ensure that. structural .inteErity of the Class 3 pipin.; would be maintained 'under ,

seismic-loads. This analysis is included as an attachment +o-Enclosure-1.- This-action van teen to show compliance with Technical Specification 3.4'.10 Action C.

2. Submit a temporary request for relief from the ASME Section XI code under 50.55a to_ address. operation during the interim period of time (approximately two weeks) until'_ a code repair can be perfortred. NRC further indicated that a-Generic 1.etter 90-05 analysis ~could not be performed for this situation, i.e., socket-weld leak.

-9112100219 911202- 1 PDR. ADOCK 0500032'l p PDR g).

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I i U.S. Nuclear Regulatory Commission December 2, 1991

3. Repu '

e ';t welds before 1l nit I restart (Mode 2) from the onging Cycle 'u. ig outage.

Enclosure 1 provides n'A's request f or relief (Item 2 above) from the ASME Section XI code. This relief requesit is being submitted under 10 CFR 50.55a(g)(5)(lii). Enclosure 2 reiterates TVA's ccmmitment to repair or replace thn affected weld material in accordance with the ASME code before restart (Mode 2) from the current t'n i t i Cycle $ cutage. Structural integrity will be maintained in the interim by monitoring the temporary alteration for furtner degradation on a weekly basis.

P' ease direct luestions concerning this issee to D. V. Goodin at (615) 343-773'..

sincerely.

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,512 L J' L. Wilson

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Enclosure ec: (Enclosure):

Mr. D. E. ballarge, Froject Manager U.S. Nuclear Regulat.ory Canmission One White Flint, North 11555 Rockville ? he Rockville, Maryland 20852 NRC Resident inspm tar Sequoyah Nuclear i'lant 2600 !gou Ferry Rs*d Soddy Daisy Tennessee 37379 Mr. B. A. Wilson, Project Wief U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 Atlanta Georgia 30323 I

, i ENCLOSURE 1 4

REQUEST FOR RELIEF--ESSENTIAL RA4 C00L1NG WATER (ERCW) ,

RELIEF VALVE P! PING TEMPORARY ALTERATION t UNIT 5: SQN Units 1 and 2

- COMPONENTS: The socket veld joint on 3/4-inch stainless steel piping '

to the Relief Valves 0-67-1514 and 2-67-1513 SYSTEM: ERCW AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE CLASS: 3 FUNCTION - The piping and relief valves provide thermal protection for the component cooling system (CCS) heat exchangers (hx's) OB2 and 2A1.

IMPRACT! CAL-CODE REQUIREMENTS: When a code repair is performed, it is required to be performod in accordance with the ASME.Section XI, IWA-4000 or IWA-7000 for the replacements, to restore structural integrity to the original design requirements. This requirement is impractical to meet

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at this time because of an ongoing modification for installing the two new plate-type CCS hx's 1A1 and 1A2.

The compensttory requirements of the safety evaluation for this modification requires the CCS hx's DB2 and 2A1  ;

to be in operation in order to support both Unit 1 and Unit 2 CCS heat loads.

BACKGROUND: A temporary alteration was installed to place bolted block clamps around the-piping in order to minimize or stop'the leakage and provide _for structural integrity to -

the piping to ensure that the piping does not degrade '

further.

l The operability of the systen,has been addressed. The flawed welds are on the discharge _ piping of the CCS "

hx's DB2 and 2A1. Even if a total failure occurred, the *

-ERCW flow on the-supply side of these nx's will not be impaired.- Therefore -these hx's are still able_to.

- perform their d(sign function. The only potential impact to the equipment downstream is the ERCW supply-to the motor-driven auxiliary feedwater pumps off the 30-inch diameter discharBe header. ' Considerable flov-margin exists f or this application. atud therefore.

,, supply _ capability would be-unaffected by the small lors of-flow. In addition, the potential impact of flooding and/or water spray on safety-related equipment has been evaluated and has been determined to not impact safe operation of the plant.

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A structural analysis of the temporary clarnps was performed to ensure that structural integrity of the  ;

piping could te nairtained (ref er to the attachment to this enclosure). Please note that Revision-1 has been issued to the original analysis. Significant margins remain to ensure structural integrity.

ALTERNATIVE REQUIREMENTS: The temporary al teration will be lef t in place until. the new Unit 1 CCS hx's lAl and 1A2 can be placed in service +

and the normal configuration is reestablished. .;

A system walkdown of the temporary alteration will be performed on a weekly basis by the system engineer. The system engineer wil'. assess the structural integrity of the temporary alteration by verifying that there is no further degradation.

A$ME code repairs or replacements will be performed before Unit i restart (Mode 2) currently scheduled for Denember 9. 1991.

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PLO90205/192  ;

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. ATTACllMENT TO ENC 1.0SURE 1 I

i WA ENGINEERING ANALYSIS FOR TEMPORARY CLAMPS INSTALLED ON C1.AES 3 PIPING B87 911121 001 i

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