ML20024H847
| 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: |
| References | |
| TAC-M85308, TAC-M85309, NUDOCS 9308260005 | |
| Download: ML20024H847 (4) | |
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1 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
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Docket Nos. 50-327 Tennessee Valley Authority
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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
Nozzle Supplemental Inspections - Sequoyah Nuclear Plant
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l Units 1 and 2 (TAC Nos. M85308 and M85309)"
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TVA letter to NRC dated January 8, 1993,'"Sequoyah 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" 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.
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).
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U.S. Nuclear Regulatory Commission 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 provides the summary report of the Unit I nozzle inspection. 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 l
Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711 i
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ENCLOSURE 1 SEQUOYAH NUCLEAR PLANT REACTOR PRESSURE VESSEL N0ZZLE UNDERCLAD INSPECTION REPORT (UNIT 1 CYCLE 6 REFUELING OUTAGE) e t
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