ML12215A337

Evaluation for Tube Vibration-Induced Fatigue

ML12215A337
Person / Time
Site:	Watts Bar
Issue date:	07/31/2012
From:	Hruby R Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML12215A337 (3)

Text

Enclosure 1 is to be withheld from public disclosure under 10 CFR § 2.390.

When separated from this enclosure, this letter is decontrolled.

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 July 31, 2012 10 CFR 50.4 U,S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391

Subject:

Watts Bar Nuclear Plant (WBN) Unit 2 - WBN Unit 2 Evaluation for Tube Vibration-Induced Fatigue

Reference:

1. TVA letter to NRC dated March 1, 1989, "Watts Bar Nuclear Plant (WBN)

Units 1 and 2 - Nuclear Regulatory Commission (NRC) Bulletin 88-02, Rapidly Propagating Fatigue Cracks In Steam Generator Tubes" This letter provides documents that TVA committed to provide in response to NRC Bulletin 88-02, "Rapidly Propagating Fatigue Cracks in Steam Generators Tubes," as detailed in the reference above.

TVA Commitment Item 4 of Enclosure 2 of the reference stated, "The results of the thermal-hydraulicanalysis and details of the permanent long-term corrective actions will be submitted to the NRC when they become available to TVA."

Commitment Closure contains the Westinghouse Electric Company (WEC) proprietary version of WCAP-1 7309-P, Revision 1, "Watts Bar Unit 2 Evaluation for Tube Vibration Induced Fatigue,"

dated February 2012. This report documents the evaluation for tube vibration-induced fatigue for the WEC Model D3 steam generators at WBN Unit 2 for susceptibly to fatigue-induced cracking of the type experienced at North Anna Unit 1 in July 1987. contains WEC non-proprietary version of WCAP-1 7309-P, Revision 1, "Watts Bar Unit 2 Evaluation for Tube Vibration Induced Fatigue," dated February 2012.

- 9O

U.S. Nuclear Regulatory Commission Page 2 July 31, 2012 As stated in 9.5 (CONCLUSIONS) of the report, the long term corrective action is as follows:

"... it is recommended that Steam Generator 4 Row 12 Column 106 through 109 tubes be removed from service. These tubes should either be plugged with sentinel plugs or plugged with solid plugs if a cable tube damper is installed. For all other tubes it is not necessary to recommend preventative action since the stress ratios and total cumulative fatigue usage of all the other unsupported U-bend tubes did not exceed the limiting value of 1.0. Steam generator tubes at Watts Bar Unit 2 (other than the four recommended to be removed from service above) are not expected to be susceptible to high-cycle fatigue rupture at the top tube support plate in a manner similar to the rupture that occurred at North Anna Unit 1. This conclusion applies to both the current specified operating conditions and to MUR uprate power operating conditions."

Note: The recommended solid tube plugs with cable tube dampers were installed as documented in WEC Field Service Report MRS-FSR-1941-WBT) contains WEC non-proprietary document CWA-12-3414, "Application for Withholding Proprietary Information from Public Disclosure WCAP-17309-P, Revision 1, 'Watts Bar Unit 2 Evaluation for Tube Vibration Induced Fatigue,"' dated February 28, 2012. contains information proprietary to Westinghouse Electric Company LLC (WEC). contains the necessary information supporting the request for withholding such information. TVA requests that the WEC proprietary information be withheld from public disclosure in accordance with 10 CFR § 2.390.

There are no new regulatory commitments contained in this letter. If you have any questions, please contact Gordon Arent at (423) 365-2004.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 3 1 st day of July, 2012.

Respectfully, Raymond A. Hruby, Jr.

General Manager, Technical Services Watts Bar Unit 2 Enclosures (see page 3)

U.S. Nuclear Regulatory Commission Page 3 July 31, 2012

Enclosures:

1. WEC Proprietary Document: WCAP-17309-P Revision 1, "Watts Bar Unit 2 Evaluation for Tube Vibration Induced Fatigue," dated February 2012.

2. WEC Non-Proprietary Document: WCAP-17309-NP, Revision 1, "Watts Bar Unit 2 Evaluation for Tube Vibration Induced Fatigue," dated February 2012.

3. WEC non-proprietary document CAW-12-3414, "Application for Withholding Proprietary Information from Public Disclosure WCAP-17309-P, Revision 1, 'Watts Bar Unit 2 Evaluation for Tube Vibration Induced Fatigue,"' dated February 28, 2012.

cc (Enclosures):

U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Resident Inspector Unit 2 Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381