ML13091A026
| ML13091A026 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 03/27/2013 |
| From: | Stinson K Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML13091A026 (4) | |
Text
Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402-2801 March 27, 2013 10 CFR 50.55(e)
U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Bellefonte Nuclear Plant, Units 1 and 2 Construction Permit Nos. CPPR-122 and CPPR-123 NRC Docket Nos. 50-438 and 50-439
Subject:
CONTAINMENT VERTICAL TENDON COUPLING FAILURE - FINAL REPORT
References:
- 1. U.S. Nuclear Regulatory Commission Operations Center Event Report No. 45559, dated December 10, 2009 (ML093490942).
- 2. Letter from TVA to NRC, "Bellefonte Nuclear Plant (BLN) Units 1 (CPPR-122) and 2 (CPPR-1 23) - Containment Vertical Tendon Coupling Failure - First Interim Report," dated December 10, 2009 (ML093480158).
- 3. Letter from TVA to NRC, "Bellefonte Nuclear Plant (BLN) Units 1 (CPPR-122) and 2 (CPPR-123) - Containment Vertical Tendon Coupling Failure - Second Interim Report," dated March 29, 2010 (ML100900090).
- 4. Letter from TVA to NRC, "Bellefonte Nuclear Plant (BLN) Units 1 (CPPR-122) and 2 (CPPR-123) - Containment Vertical Tendon Coupling Failure.- Third Interim Report," dated September 20, 2010 (ML102660164).
- 5. Letter from TVAto NRC, "Bellefonte Nuclear Plant (BLN) Units 1 (CPPR-122) and 2 (CPPR-1 23) - Containment Vertical Tendon Coupling Failure - Fourth 'Interim Report," dated March 29, 2011 (ML110940042).
6.. Letter from TVA to NRC, "Bellefonte Nuclear Plant (BLN) Units 1 (CPPR-122) and 2 (CPPR-123) - Containment Vertical Tendon Coupling Failure - Fifth Interim Report," dated March 29, 2012 (ML12093A401).
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U.S. Nuclear Regulatory Commission Page 2 March 27, 2013 The purpose of this letter is to provide the final report on the containment vertical tendon coupling failure, which TVA initially reported to the NRC Operations Center on December 10, 2009 (Reference 1). TVA has submitted five interim reports (References 2, 3, 4, 5 and 6) on this subject. TVA's fifth interim report described further actions being pursued within the Bellefonte corrective action program under Problem Evaluation Report (PER) 200119. The PER work effort has produced information deemed sufficient to support the final determination whether the subject failure is reportable pursuant to the requirements in 10 CFR 50.55(e).
The evaluations and supporting laboratory analyses of the Bellefonte Unit 1 V9 containment vertical tendon coupling failure on August 17, 2009 conclude the failure mode to be hydrogen-induced stress corrosion cracking (SCC). The root cause of failure was determined to be water and sulfides in the grease surrounding a high stress area of the failed coupling.
The evaluations to determine the extent of condition have found no SCC indications for any tendon component other than the failed V9 containment vertical tendon coupling. The vertical tendons are essential to the safety-related functions of the reactor building primary containment structure. The evaluations included performing the following activities:
" TVA reviewed applicable design specifications, design drawings, material test reports, as-built material properties, installation and maintenance history records, and operating experience, and concluded that the BLN design and added controls were adequate to minimize the introduction of water and sulfur contamination.
" TVA conducted grease analyses consistent with NRC Regulatory Guide (RG) 1.35 on the lower grease cans of all the Unit 1 containment vertical tendons. The grease inspection of the V41 vertical tendon detected a relatively small quantity of water, but did not detect any sulfur or other contaminants. The grease inspections for the remaining 183 vertical tendons did not detect the presence of water, sulfur or other contaminants, and determined the grease samples were within the applicable design specification limits.
TVA detensioned, disassembled and performed non-destructive examination (NDE) testing on the coupling heads, couplers and tendons for the two vertical tendons (V41 and V121) determined to be potentially high-risk, one randomly selected horizontal tendon (106BD),
and one randomly selected dome tendon (D3C17). In addition, RG 1.35 prescribed tests of grease samples at each end of these tendons were performed. The analysis and test results revealed no evidence of SCC and determined the material properties were within applicable design specification limits&
Based on the above results, the Bellefonte Unit 1 V9 containment vertical tendon coupling failure on August 17, 2009 does not represent a deviation that extends to other Unit 1 containment-tendons and does not represent a deviation originating with the tendon supplier.
Finally, the evaluation results indicate the deviation does not represent a substantial safety hazard and is not reportable pursuant to the requirements in 10 CFR Section 50.55(e).
Although TVA determined the deviation does not represent a substantial safety hazard and is not reportable, follow-on corrective actions for the subject containment vertical tendon coupling failure condition will continue to be assessed under PER 200119.
U.S. Nuclear Regulatory Commission Page 3 March 27, 2013 There are no regulatory commitments contained in this letter.
If you have any questions or require additional information, please do not hesitate to contact Martin Bryan at (256) 574-8265.
Respectfully, K. D. Stinson Vice President Bellefonte Project cc: See page 4 Subscribed and sworn to before me on t hi4 l-- day of Notary Public "
My Commission Expires 4m4Ž )- -
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U.S. Nuclear Regulatory Commission Page 4 March 27, 2013 cc:
Eric J. Leeds, Director Robert C. Haag U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission One White Flint North, 13H16M Region II 11555 Rockville Pike Marquis One Tower Rockville, Maryland 20852-2738 245 Peachtree Center Ave. NE, Suite 1200 Atlanta, Georgia 30303-1257 Jessie F. Quichocho, Chief for Plant Christopher J. Even Licensing Branch 11-2 U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Region II One White Flint North, 8G9A Marquis One Tower 11555 Rockville Pike 245 Peachtree Center Ave. NE, Suite 1200 Rockville, Maryland 20852-2738 Atlanta, Georgia 30303-1257 Justin C. Poole, Sr. Project Manager U.S. Nuclear Regulatory Commission One White Flint North, 8G9A 11555 Rockville Pike Rockville, Maryland 20852-2738 Victor M. McCree, Regional Administrator U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave. NE, Suite 1200 Atlanta, Georgia 30303-1257 Frederick D. Brown, Deputy Regional Administrator for Construction U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Avenue NE, Suite 1200 Atlanta, Georgia 30303-1257