ML20128K013

Forwards SE Accepting Util Justification for Break Exclusion of Main Steam Lines in Valve Vaults Provisionally Until End of Refueling Outages

ML20128K013
Person / Time
Site:	Sequoyah
Issue date:	02/11/1993
From:	Labarge D Office of Nuclear Reactor Regulation
To:	Medford M TENNESSEE VALLEY AUTHORITY
Shared Package
ML20128K017	List: ML20128K013 ML20128K022
References
TAC-M84828, NUDOCS 9302180043
Download: ML20128K013 (3)

Text

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%  ! February ll, 1993 Docket Nos. 50-327 and 50-328 Tennessee Valley Authorit ATTN: - Dr. Mark 0. Medfot ,, Vice President Nuclear Assurance, Licensing & Fuels 3B Lookout Place

. 1101 Market Street Chattanooga, Tennessee 37402-2801

SUBJECT:

JUSTIFICATION FOR CONTINUED OPERATION - SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 (TAC NO. M84828)

By Licensee Event Report No. 50-327/92013, dated August 17, 1992, the Tennessee Valley Authority (TVA), licensee for the Sequoyah Nuclear Plant, Un'its 1 and 2, reported that Westinghouse Electric Corporation had determined that the mass and energy releases during a double-ended guillotine steam line break in the main steam valve vaults were not :onservatively calculated. The mass and energy releases were recalculated using a more realistic methodology described in ANSI /ANS Standard 58.2, 1980. The use of this methodology significantly increased the mass and energ" releases in the vaults, such that the calculated pressures exceeded the design margins and the structural adequacy of the concrete walls and roof slabs could not be assured.

As a result of this determination, TVA prepared a Justification for Continued Operation (JCO), which was based on showing that the main steam piping within the vaults meets the break exclusion provisions of Standard Review Plan (SRP)

Branch Technical Position (BTP) MEB 3-1, " Postulated Rupture Locations in Fluid System Piping Inside and Outside Containment." Although the vaults are not part of the containment penetration areas, TVA argued tnat the vaults can be categorized as a containment penetration area on the basis that the design criteria for both were the same.

Discussions concerning the JC0 were held with Region Il and Nuclear Reactor Regulation (NRR) staff personnel on July 17 and 24, 1992. At that time, the staff determined that the JC0 satisfactorily resolved the concerns for plant operation until each unit's next refueling outage.

At the request of the staff, TVA submitted the JC0 by letter dated November 30, 1992. NRR has reviewed the JC0 and concluded that the break exclusion of the main steam lines within the valve vaults is acceptable until the refueling outages for Unit 1 and 2 scheduled to start in April and September 1993, respectively. Our safety evaluation is enclosed.

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PDR ADOCK 05000327 P PDR

Dr. Mark 0. Medford It is the staff's understanding that new engineering analysis has shown that by modifying some pipe supports, the original design basis for the main steam line break accident analysis inside the valve vaults will be restored. The modifications will be performed prior to startup from the 1993 refueling outage for each unit. Following the modifications, reliance on the break exclusion criteria described in Branch Technical Position MEB 3-1 will no longer be necessary.

Sincerely, Original sii ed by David E. LaBarge, Senior Project Manager Project Directorate 11-4 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation

Enclosure:

Safety Evaluation cc w/ enclosure:

See next page

' Distribution Docket File' NRC & Local PDRs SQN Rdg. File S. Varga 14-E-4 G. Lainas 14-H-1 F. Hebdon _

D. LaBarge M. Sanders OGC 15-B-18 M. Hartzman J. Norberg ACRS(10)

E. Herschoff Rll B. Wilson RIl P. Kellogg Ril W. Holland Rll 0fC PDil-4/LA PDII-4/PMik[ PDilr4/D NAME MSandersh/ DLaBarge:ak FHYt/ don DATE Ci //9/93 2_/1o/93 3 /ti/93

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-Tennessee Valley Authority Sequoyah Nuclear Plant ATIN: Dr. Mark O. Medford cc:

Mr. John B. Waters, Chairman County Judge Tennessee Valley Authority Hamilton County Courthouse ET 12A Chattanooga, Tennessee 37402 400 West Summit Hill Drive Knoxville, Tennessee 37902 Regional Administrator U.S.N.R.C. Region II Mr. J.~R. Bynum, Vice President 101 Marietta Street, N.W.

Nuclear Operations Suite 2900 3B Lookout Place Atlanta, Georgia 30323 1101 Market Street Chattanooga, Tennessee 37402-2801 Mr. William E. Folland Senior Resident Inspector Sequoyah Nuclear Plant

!!r. M. J. Burzynski, Manager U.S.N.R.C.

Nuclear Licensing and Regulatory Aire 1rs 2600 Igou Ferry Road Tennessee Valley Authority Soddy Daisy, Tennessee 37379 5B Lookout Place Chattanooga, Tennessee 37402-2801 Mr. Jack Wilson, Vice President Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, Tennessee 37379 TVA Representative Tennessee Valley Authority 11921 Rockville Pike Suite 402 Rockville, Maryland 20852 Ms. Marci Cooper, Site Licensing Manager Sequoyah Nuclear Plant Tennessee Valley Authority P,0. Box 2000 Soddy Daisy, Tennessee 37379 Mr. Michael H. Mobley, Director Division of Radiological Health 3rd Floor, L and C Annex 401 Church Street Nashville, Tennessee 37243-1532 General Counsel Tennessee Valley Authority ET llH 400 West Summit Hill Drive Knoxville, Tennessee 37902 l

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