ML20107M716

Provides Addl Info for ASME Section XI Relief Request

ML20107M716
Person / Time
Site:	Sequoyah
Issue date:	04/24/1996
From:	Shell R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9605010085
Download: ML20107M716 (4)

Text

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En Tennessee Vabey Authority. Post cff.ce Box 2000. Soddy-Da:sy Tencessee 37373 l

April 24,1996 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of

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Docket Nos. 50-327 Tennessee Valley Authority

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50-328 SEQUOYAH NUCLEAR PLANT (SON)- ADDITIONAL INFORMATION FOR AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) SECTION XI RELIEF REQUEST -

l SNUBBERS

References:

1. TVA letter to NRC dated October 26,1995, "Sequoyah Nuclear Plant (SON) - American Society of Mechanical Engineers (ASME)Section XI Relief Request - Snubbers"

2. TVA letter to NRC Dated March 6,1996, "Sequoyah Nuclear Plant (SON)- Additional Information for American Society of Mechanical Engineers (ASME)Section XI Relief Request - Snubbers" l

3. NRC letter to TVA dated March 25,1982,"Issuange of Amendment No.12 to Facility Operating License No. DPR Sequoyah Nuclear Plant, Unit 1" TVA, by the Reference 1 letter, submitted a request for relief to exempt applicable snubbers from the ASME Section XI code requirements and, as an alternative, perform examinations and tests in accordance with SON's technical specifications (TS).

In response to an NRC request, TVA is withdrawing a portion of its original request for relief associated with the requirements of ASME Section XI, Subarticle IWF-5200 entitled, "Preservice Examinations and Tests." TVA concurs with NRC that relief from IWF-5200 would not be necessary because IWF-5200 applies to preservice examination of nuclear plants under construction, in addition, NRC requested additionalinformation concerning why SON's TS for snubbers contains an allowance for two functional test failures within a test lot before 9605030085 960424 PDR ADOCK 05000327 p

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U.S. Nuclear Regulatory Commission Page 2 April 24,1996 testing additionallots, while the ASME code requires testing additionallots as a result of a single test failure. In response to this request, TVA provides the following:

Surveillance requirements (SRs) for snubbers were incorporated into the SON Unit 1 TSs under Amendment 12 (see Reference 3). Similar changes were approved for l

SON's Unit 2 TSs. These SRs resulted from an April 17,1981, meeting between TVA l

and NRC staff members H. Shaw and M. Virgilio. Agreements reached in the meeting resulted in TVA's amendment request to NRC dated August 28,1981.

SON's total population of safety-related snubbers is divided into five subgroups on each unit. Four subgroups are based on design and snubber type while the fifth subgroup is based on environment. For four out of the five subgroups, SON's l

functional test program limits the snubber failure rate to one snubber within a l

subgroup before testing additionallots. This approach is consistent with ASME code l

and is more conservative than the failure rate allowed by SON TSs (i.e., two failures

~per TS SR 4.7.9.f). For one of SON's five subgroups (i.e., midsize mechanical snubbers subgroup on Unit 1), SON's Snubber Test Program incorporates the TS by allowing the failure rate to increase to two. This allowance is based on the larger population of snubbers (235) within this subgroup. TVA has evaluated applying the j

conservative ASME code failure rate to this subgroup and concludes that this l

approach does not result in a significant impact to SON's functional test activities, i

l Accordingly, TVA will revise SON's Snubber Test Program (Surveillance Instruction O-SI-MFT-000-001.0)to limit the failure rate within this subgroup to one (refer to enclosure for the TVA commitment). This approach will apply the same failure rate limit to a!I subgroups and will provide consistency with the ASME code requirements.

in conclusion, TVA proposes to: (1) withdraw IWF-5200 from SON's original relief j

request letter (Reference 1), and (2) with the exception of TS SR 4.7.9.f, request l

exemption for applicable snubbers from the 1989 Edition of the ASME Section XI l

Code, and as an alternative, perform examination and testing in accordance with SON l

TS SR 3/4.7.9, " Snubbers." With regard to TS SR 4.7.9.f, TVA will limit SON's snubber test failure rate to one failure.

Please direct questions concerning this issue to D. V. Goodin at (423) 843-7734.

Sincerely, R. H. Shell Manager 3

SON Site Licensing Enclosure cc: See page 3

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U.S. Nuclear Regulatory Commission Page 3 April 24,1996 cc (Enclosure):

i Mr. D. E. LaBarge, Project Manager Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 j

NRC Resident inspector Sequoyah Nuclear Plant 2600Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Comrr.ission Region il l

101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711 i

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Enclosure TVA Commitment TVA will revise SON's Snubber Test Program (Surveillance Instruction 0-SI-MFT-000-001.0) to limit the allowed failure rate to one. This revision will be complete by June 21,1996.

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