ML20024H847

Forwards Rev 2 of MEM-MNA-296(93), Evaluation of Ultrasonic Test Results from 1993 ISI on Underclad Flaw Indications in Sequoyah,Unit 1 Rv Nozzles. Commitments for Performing Exam of Unit 1 RPV at End of Second 10-yr ISI Interval Also Encl

ML20024H847
Person / Time
Site:	Sequoyah
Issue date:	08/18/1993
From:	Fenech R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20024H848	List: ML20024H847 ML20024H849
References
TAC-M85308, TAC-M85309, NUDOCS 9308260005
Download: ML20024H847 (4)

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Tennessee Valley Authontv. Post Offce Box 2000 Soddy-Da:sv. Temessee 37379-2000 Robert A. Fenech vce Presdent. Sequoyah Naclear Ptant August 18, 1993 U.S. Nuclear Regulatory Commission -

ATTN: Document Control Desk  ;

Washington, D.C. 20555 i

Gentlemen:  !

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - RESULTS OF THE REACTOR PRESSURE VESSEL ,

(RPV) N0ZZLE INSPECTION FOR UNDERCLAD CRACKS - UNIT 1 i

References:

1. NRC letter to TVA dated April 16, 1993, " Reactor Vessel l l Nozzle Supplemental Inspections - Sequoyah Nuclear Plant )

l Units 1 and 2 (TAC Nos. M85308 and M85309)" i

2. TVA letter to NRC dated January 8, 1993,'"Sequoyah l Nuclear Plant (SQN) - Technical Specification (TS) j Change 92 Deletion of TS Surveillance Requirement '

(SR) 4.4.10.b - Supplemental Exam of Reactor Vessel l Nozrles" l

The purpose of this letter is to provide NRC with a summary report of the j SQN ultrasonic inspections of the Unit 1 RPV nozzles for underclad l cracking that was completed during the Unit 1 Cycle 6 (U1C6) refueling l outage. The summary report was prepared by Westinghouse Electric j Corporation for TVA and contains the results of the nozzle inspection and j a flaw evaluation. l l

In summary, the RVP nozzle underclad flaw indications identified in 1980 i could not be directly compared with the 1993 (U1C6) inspection results because of the inherent difference in inspection technology and the robotic application of the ultrasonic inspection.- The inspections completed during the UIC6 refueling outage will serve as baselice data for comparison during the next 10-year inspection interval (i.e., end of 1 the second 10-year in-service inspection [ISI) interval for Unit 1). j i

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U.S. Nuclear Regulatory Commission 3 Page 2 August 18, 1993 -

i The flaws detected during the UIC6 inspection are less than the flaw acceptance standards defined in the American Society of Mechanical -

Engineers code,Section XI, IWB-3500. Therefore, the flaws do not affect the RPV structural integrity or design margin of SQN Unit 1.

In accordance with the Reference 2 letter, TVA submitted a proposed TS j change for Units 1 and 2 (TS Change 92-16) that deletes a supplemental l l examination requirement associated with inspecting SQN's reactor vessel i l nozzles for underclad cracking (TS SR 4.4.10.b). In Reference 1, NRC l

noted that a further review of TVA's requested TS amendment and its

! application for the Unit 2 Cycle 6 refueling outage awaiting NRC's review of the results of the Unit 1 examination. The underclad crack phenomena ,

do not exist for Unit 2. Thus, TS SR 4.4.10.b should be removed from the j l

Unit 2 TSs. TVA requests that NRC proceed with their proposed TS l amendment for Units 1 and 2 as submitted. Rather than retain the l

examination requirement within SQN's Unit 1 TSs, TVA will maintain the current examination requirement within SQN's augmented ISI program (Surveillance Instruction [SI] 114.1).

TVA has enclosed a commitment to revise SQN's augmented ISI program t (SI-114.1) to require the examination of the Unit 1 RPV nozzles for  ;

underclad cracking. This augmented examination will require that the  !

ultrasonic technique be at least as sensitive as that used to conduct the examination during the UIC6 refueling outage. The UIC6 examination will serve as a baseline examination for future examinations. The augmented examination will be performed at the end of the second 10-year ISI interval for Unit 1. The results of the augmented examination will be submitted to NRC for review and evaluation. A determination may be made at that time whetber future 10-year examinations would be required. i Enclosure 1 provides the summary report of the Unit I nozzle inspection.

Enclosure 2 contains TVA's commitment for performing the examination of the Unit 1 RPV nozzles at the end of the second 10-year ISI interval.

Please direct questions concerning this issue to D. V. Goodin at (615) 843-7734.

Sincerely, sh2gdkyfkIf-i? 'a-d(

Robert A. Fenech j Enclosures cc: See page 3 i

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l U.S. Nuclear Regulatory Commission Page 3 August 18, 1993 ,

l Enclosures cc (Enclosures):

Mr. D. E. LaBarge, Project Manager U.S. Nuclear Regulatory Commission .

One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 l

• l NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator j U.S. Nuclear Regulatory Commission Region II -

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

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l ENCLOSURE 1 SEQUOYAH NUCLEAR PLANT  :

REACTOR PRESSURE VESSEL N0ZZLE UNDERCLAD INSPECTION REPORT (UNIT 1 CYCLE 6 REFUELING OUTAGE) ,

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