ML060890314

Summary of Conference Calls, 2005 Steam Generator Tube Inspections

ML060890314
Person / Time
Site:	Comanche Peak
Issue date:	05/18/2006
From:	Thadani M Plant Licensing Branch III-2
To:	Blevins M TXU Power
Thadani M
Shared Package
ML061100059	List: ML060890314
References
TAC MC8621
Download: ML060890314 (7)

Text

May 18, 2006 Mr. M. R. Blevins Senior Vice President &

Chief Nuclear Officer TXU Power Attn: Regulatory Affairs Department P. O. Box 1002 Glen Rose, TX 76043

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION -

SUMMARY

OF TELEPHONE CONFERENCE CALLS WITH TXU GENERATION COMPANY, LP, REGARDING FALL 2005 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MC8621)

Dear Mr. Blevins:

On September 20 and October 20, 2005, the Nuclear Regulatory Commission (NRC) staff, participated in telephone conference calls with TXU Generation Company, LP (the licensee) staff, regarding Comanche Peak Steam Electric Station (CPSES), Unit 1, 2005 steam generator tube inspections.

In support of these calls, the licensee provided three discussion documents to facilitate the telephone conferences. The first document was transmitted in support of the September 20, 2005, pre-outage conference call. The second document was transmitted to support the October 20, 2005, mid-outage call. A third document was transmitted by the licensee on October 24, 2005, in order to provide follow-up information from the October 20, 2005, call.

A summary of the conference calls is enclosed for your information. The September 20 and October 20 and 24, 2005, documents are attached to the conference calls summary. This completes our actions under Task Action Commitment (TAC) No. MC8621.

Normally, the licensee provides the steam generator inspection summary reports to the NRC in accordance with the plants technical specification requirements, and the NRC staff reviews the reports as a separate action and under a separate TAC. The licensees typically submit these summary reports within one year of the completion of the steam generator inspections.

M. R. Blevins In accordance with those procedures, the steam generator inspection reports will be reviewed under a new TAC.

If there are any questions, please contact me at (301) 415-1476.

Sincerely,

/RA/

Mohan C. Thadani, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-445

Enclosure:

Summary of Conference Calls cc w/encl: See next page

M. R. Blevins In accordance with those procedures, the steam generator inspection reports will be reviewed under a new TAC.

If there are any questions, please contact me at (301) 415-1476.

Sincerely,

/RA/

Mohan C. Thadani, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-445

Enclosure:

Summary of Conference Calls cc w/encl: See next page DISTRIBUTION:

PUBLIC LPLIV Reading RidsOgcRp RidsAcrsAcnwMailCenter RidsNrrDorlLplg RidsNrrPMMThadani RidsNrrLADJohnson RidsRgn4MailCenter AHiser MMurphy JClark MYoder PACKAGE ACCESSION NO.: ML061100059 LETTER ACCESSION NO.: ML060890314 ATTACHMENT 1 TO ENCL: ML061220456 ATTACHMENT 2 TO ENCL: ML061220448 ATTACHMENT 3 TO ENCL: ML061220436 *no significant change to the SE input OFFICE NRR/LPL4/PM NRR/LPL4/LA CSGB/BC NRR/LPL4/BC NAME MThadani DJohnson Allen Hiser* DTerao DATE 5/18/06 5/18/06 12/20/2006 5/18/06 OFFICIAL RECORD COPY

FALL 2005 TELEPHONE CONFERENCE CALL

SUMMARY

STEAM GENERATOR TUBE INSPECTIONS COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 1 DOCKET NO. 50-445 On September 20 and October 20, 2005, the Nuclear Regulatory Commission (NRC) staff participated in telephone conference calls with TXU Generation Company LP (the licensee) staff regarding the fall of 2005 (1RF11) steam generator tube inspections of Comanche Peak Steam Electric Station (CPSES), Unit 1.

CPSES, Unit 1 is a four-loop Westinghouse Electric Company (Westinghouse) pressurized water reactor with four Westinghouse Model D4 recirculating steam generators. Each steam generator contains 4578 mill annealed Alloy 600 tubes, which are nominally 0.750 inches in diameter and have a nominal tube wall thickness of 0.043 inches. The tubes are supported by carbon steel tube support plates (TSPs) and chromeplated Alloy 600 anti-vibration bars (AVBs).

The September 20, 2005, call focused on the scope of the licensees base eddy current inspections conducted during the 1RF11 outage in October 2005. The licensee also discussed the potential for expansion of the base eddy current inspections, if necessary. The plans for base eddy current inspections are described in the document provided by the licensee in support of this call and is provided as Attachment 1 to this summary. Additional clarifying information and information not included in the document provided is summarized below:

The 100% +Point' coil examination of hard rolled tubes at the top of tubesheet (TTS +/- 3"), as described in the inspection plan, bounds the licensees F* evaluation.

The inspection plan indicates that 100% of all dented TSP intersections greater than or equal to 2 volts in magnitude at the H3 support will be inspected with +Point' coil. During the call, CPSES staff indicated that this inspection may be expanded to the H4 support, depending on the results of the H3 support inspections.

Paired dings are generally caused by the manufacturing process. In 1999, South Texas Project observed outer diameter stress corrosion cracking at a paired ding. Degradation at paired dings has never been identified at CPSES.

During the 1RF10 (2004) outage, 100% of the tungsten inert gas (TIG) sleeves installed in the 1RF09 (2002) outage were inspected. A 20% sample of these sleeves is included in the 2005 inspection plan. The plan is to inspect from 3 inches above the top of the sleeve to 3 inches below the bottom of the sleeve with a +Point' coil.

Enclosure

There are no plans to perform rotating probe inspections on wear indications at AVB locations.

This decision is based on experience gained through hundreds of prior inspections of cold leg baffle wear locations that have never identified cracks within the wear.

The October 20, 2005, call focused on the topics provided to CPSES by the NRC staff. These topics and the plants response (based on the information available at the time of the call) are provided as Attachment 2 to this summary. Additional clarifying information and information not included in the document provided is summarized below:

Following the September 20, 2005, call, the licensee increased the scope of its examinations to include a +Point' inspection of 100% of the wear scars at AVBs (7 locations) and 20% of the wear scars at baffle plates. The licensee also increased the scope of its examination of TIG sleeves to include a partial length inspection from 3 inches above to 3 inches below the top of the sleeve. These exams were added since the capabilities of the bobbin coil in this region are limited.

All indications at hard rolled locations were located in the expansion transition region.

Indications identified for the longest extent and largest voltage in the document provided are not necessarily the same indication. In most cases the indication with the largest voltage was found in a different tube than the indication with the longest extent.

The two volumetric indications identified at tube supports are small scars that appear to have originated from a foreign body that was lodged between the tube and the tube support. This foreign body is no longer present. These indications have been tracked for several outages.

One freespan indication identified on the outer diameter (OD), was an axial indication that spanned approximately 33 inches. The maximum voltage of this indication was 0.25 volts.

No flaws were identified at dent locations.

No cracks were identified at wear scars.

The licensee plans to repair 7 tubes due to partially-collapsed TIG-welded sleeves. These sleeves had been in service for 2 operating cycles and appeared to show minor deformation. A 0.540 inch diameter bobbin coil would not pass through the sleeve locations, which would normally have a nominal inside diameter of 0.561 inches. A 0.50 inch rotating probe was able to pass through the sleeve location.

With respect to the freespan indications detected during the outage, a few were deeper than that observed in the past outage and there was a higher density of cracking than the previous outage.

With respect to the axially-oriented OD-initiated indications at the TSPs, the number observed is about the same as that observed in prior outages.

Enclosure

With respect to the low row U-bend examinations, rows 3 through 10 are generally considered susceptible to circumferential degradation and rows 3 through 8 are generally considered susceptible to axial degradation. Tubes in rows 17 through 22 may have some ovality associated with them.

During the last outage at CPSES, Unit 1, a circumferential (oblique) indication was found in the U-bend region of a row 13 tube.

At the time of the call, inspections in the U-bend and at special interest locations were still ongoing.

At the conclusion of the October 20, 2005, call, the NRC staff requested that the licensee provide some supplemental information once it had completed its inspections. The information requested included 1) a discussion of the +Point' coil inspections performed in the U-bend region, 2) further information about any in-situ pressure tests performed, and 3) a discussion of the performance of the Primary and Secondary Analyses with respect to freespan axial indications. The requested information was submitted by the licensee and is provided as to this summary as follow-up information, following the October 20, 2005, call.

Based on the information provided, the staff did not identify any technical issues that warranted follow-up action at this time.

Attachments:

1. September 20, 2005, Conference Call Summary

2. October 20, 2005, Conference Call Summary

3. Answers to Follow-up Questions Enclosure

Comanche Peak Steam Electric Station cc:

Senior Resident Inspector Mr. Brian Almon U.S. Nuclear Regulatory Commission Public Utility Commission P. O. Box 2159 William B. Travis Building Glen Rose, TX 76403-2159 P. O. Box 13326 1701 North Congress Avenue Regional Administrator, Region IV Austin, TX 78701-3326 U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Ms. Susan M. Jablonski Arlington, TX 76011 Office of Permitting, Remediation and Registration Mr. Fred W. Madden, Director Texas Commission on Environmental Regulatory Affairs Quality TXU Generation Company LP MC-122 P. O. Box 1002 P. O. Box 13087 Glen Rose, TX 76043 Austin, TX 78711-3087 George L. Edgar, Esq. Terry Parks, Chief Inspector Morgan Lewis Texas Department of Licensing 1111 Pennsylvania Avenue, NW and Regulation Washington, DC 20004 Boiler Program P. O. Box 12157 County Judge Austin, TX 78711 P. O. Box 851 Glen Rose, TX 76043 Environmental and Natural Resources Policy Director Office of the Governor P. O. Box 12428 Austin, TX 78711-3189 Mr. Richard A. Ratliff, Chief Bureau of Radiation Control Texas Department of Health 1100 West 49th Street Austin, TX 78756-3189