ML042570229

Summary of Meeting with Tennessee Valley Authority Regarding Potential Fabrication Damage to Steam Generator Tubes at Sequoyah, Unit 1

ML042570229
Person / Time
Site:	Sequoyah
Issue date:	09/10/2004
From:	Robert Pascarelli NRC/NRR/DLPM/LPD2
To:	Tennessee Valley Authority
Pascarelli,R J,NRC/NRR/DIPM,415-1245
References
TAC MC3377
Download: ML042570229 (4)

Text

September 10, 2004 LICENSEE:

Tennessee Valley Authority FACILITY:

Sequoyah Nuclear Plant, Unit 1

SUMMARY

OF MAY 20, 2004, TELEPHONE CONFERENCE WITH TENNESSEE VALLEY AUTHORITY REGARDING POTENTIAL FABRICATION DAMAGE TO THE STEAM GENERATOR TUBES AT SEQUOYAH, UNIT 1 (TAC NO. MC3377)

On May 20, 2004, a telephone conference was held between the staff of the U.S. Nuclear Regulatory Commission (NRC) and representatives of Tennessee Valley Authority (TVA). The purpose of the meeting was to discuss recent operating experience related to steam generator fabrication and its potential applicability to Sequoyah Nuclear Plant, Unit 1.

AB Sandvik Materials Technology manufactures tubes used in nuclear steam generators. After manufacturing the tubes, Sandvik packages the tubes and sends them to a steam generator fabricator. There are several steam generator fabricators. Following the unpacking of tubes manufactured by Sandvik, a steam generator fabricator (Ansaldo) noticed several tubes were damaged by screws used in the packing container. As a result of this finding, Sandvik notified the NRC formally by submitting a report pursuant to Part 21 of Title 10 of the Code of Federal Regulations. In this report (ML041410445), Sandvik indicated that the tubes manufactured for the replacement steam generators at Sequoyah, Unit 1, were also packaged using screws.

As a result of this notification, the NRC held a conference call with TVA on May 20, 2004, to ensure they were aware of the finding of damaged tubes and to discuss any actions they have taken to address the issue. The Sequoyah, Unit 1, steam generator tubes were manufactured by Sandvik and the steam generators were fabricated by Doosan.

During the call, the licensee indicated they were aware of the Sandvik report which indicated that tubes had been identified with damage as a result of the packing procedure. In addition, they indicated that they entered this condition into their corrective action program.

The licensee also indicated that they do not believe there is an immediate safety concern at Sequoyah, Unit 1, for several reasons. These reasons are discussed below.

The Sandvik tubes found to be damaged by screws by the steam generator fabricator were for steam generators that employ square bends (i.e., 90-degree bends) rather than the U-shaped used in the Sequoyah, Unit 1, steam generators. As a result, the tubes at Sequoyah, Unit 1, do not have a long horizontal run between the square bends and are, therefore, supported differently in the packing container (i.e., the U-bends dont need additional support). In addition to the differences in the packaging of the tubes, the TVA representatives indicated that they had sent representatives to Sandvik to ensure they followed their packing procedures.

Since the replacement steam generators were placed into service, there has been no primary-to-secondary leakage at Sequoyah, Unit 1, indicating that there is no through-wall penetration. This provides confidence that if any damage did occur, it was not through-wall (nor did it tear through-wall during the hydrostatic test following fabrication).

With respect to the inspection of the tubes, the licensee indicated that during the preservice inspection all (113) dents greater than 2 volts were inspected with a rotating probe. None of the dents were anomalous (i.e., the licensee believes that any anomalous dents such as that observed associated with a tube damaged by a screw would have been identified). In addition, the licensee recently reviewed the largest dent in their steam generator and concluded it was not similar to the dent found at another plant where a screw had damaged the tube.

To provide added confidence that none of the tubes were severely damaged during fabrication by a screw, the licensee currently plans to inspect all dents greater than 2 volts with a rotating probe (+PointTM) during their next steam generator tube inspection (which is currently planned for October 2004). In addition, they indicated the analysts would be trained to identify tubes damaged by screws.

The licensee also indicated that they were not aware of any tubes being rejected by their steam generator fabricator (Doosan). In addition, they were not aware of any leakage during the primary or secondary side hydrostatic test performed on their steam generators.

At the end of the conference call, the staff verified that the TVA representatives were aware of qualification work being performed by another utility to confirm the capabilities of the rotating probe at detecting steam generator tube fabrication damage. The TVA representatives were aware of this effort.

Please direct any inquiries to Ken Karwoski at 301-415-2752, or [KJK1@nrc.gov].

/RA/

Robert J. Pascarelli, Project Manager, Section 2 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-327 cc: See next page

ML042570229 NRC-001 OFFICE PDII-2/PM PDII-2/LA PDII-2/SC (A)

NAME RPascarelli BClayton MMarshall DATE 8/23/04 8/23/04 9/10/04

Tennessee Valley Authority SEQUOYAH NUCLEAR PLANT cc:

Mr. Karl W. Singer Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801 Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. James E. Maddox, Vice President Engineering & Technical Services Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Randy Douet Site Vice President Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 General Counsel Tennessee Valley Authority ET 11A 400 West Summit Hill Drive Knoxville, TN 37902 Mr. John C. Fornicola, Manager Nuclear Assurance and Licensing Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Mark J. Burzynski, Manager Nuclear Licensing Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. Pedro Salas, Manager Licensing and Industry Affairs Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 Mr. David A. Kulisek, Plant Manager Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 Senior Resident Inspector Sequoyah Nuclear Plant U.S. Nuclear Regulatory Commission 2600 Igou Ferry Road Soddy Daisy, TN 37379 Mr. Lawrence E. Nanney, Director Division of Radiological Health Dept. of Environment & Conservation Third Floor, L and C Annex 401 Church Street Nashville, TN 37243-1532 County Mayor Hamilton County Courthouse Chattanooga, TN 37402-2801 Ms. Ann P. Harris 341 Swing Loop Road Rockwood, Tennessee 37854