ML051400035
| ML051400035 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 06/03/2005 |
| From: | Gratton C NRC/NRR/DLPM/LPD2 |
| To: | Grissette D Southern Nuclear Operating Co |
| Gratton C, NRR/DLPM, 415-1055 | |
| References | |
| Download: ML051400035 (5) | |
Text
June 3, 2005 Mr. D. E. Grissette Vice President Southern Nuclear Operating Company, Inc.
P.O. Box 1295 Birmingham, AL 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING STATION (VOGTLE), UNIT 1 -
SUMMARY
OF CONFERENCE CALL REGARDING THE 2005 SPRING OUTAGE STEAM GENERATOR TUBE INSPECTIONS
Dear Mr. Grissette:
On March 28, 2005, the Nuclear Regulatory Commission (NRC) staff participated in a conference call with Vogtle, Unit 1 representatives regarding the detection of crack-like indications in the portion of the steam generator tube within the tubesheet. The NRC staff is forwarding the enclosed summary for your information.
Sincerely,
/RA/
Christopher Gratton, Sr. Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-424
Enclosure:
March 28 Conference Call Summary cc w/encl: See next page
June 3, 2005 Mr. D. E. Grissette Vice President Southern Nuclear Operating Company, Inc.
P.O. Box 1295 Birmingham, AL 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING STATION (VOGTLE), UNIT 1 -
SUMMARY
OF CONFERENCE CALL REGARDING THE 2005 SPRING OUTAGE STEAM GENERATOR TUBE INSPECTIONS
Dear Mr. Grissette:
On March 28, 2005, the Nuclear Regulatory Commission (NRC) staff participated in a conference call with Vogtle, Unit 1 representatives regarding the detection of crack-like indications in the portion of the steam generator tube within the tubesheet. The NRC staff is forwarding the enclosed summary for your information.
Sincerely,
/RA/
Christopher Gratton, Sr. Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-424
Enclosure:
March 28 Conference Call Summary cc w/encl: See next page DISTRIBUTION:
PUBLIC CHawes RidsOgcRp PDll-2 Rdg.
RidsNrrPMCGratton RidsAcrsAcnwMail Center RidsNrrDlpmLpdii1 RidsNrrPMSMonarque RidsRgn2MailCenter Accession No.: ML051400035 NRR-106 OFFICE DLPM:PM DLPM:LA DE:EMCB DLPM:SC NAME CGratton CHawes LLund SMonarque for EMarinos DATE 5/31/05 5/31/05 4/12/05 6/3/05 OFFICIAL RECORD COPY
Vogtle Electric Generating Plant, Unit 1 cc:
Mr. N. J. Stringfellow Manager, Licensing Southern Nuclear Operating Company, Inc.
P.O. Box 1295 Birmingham, AL 35201-1295 Mr. Skip Kitchens, General Manager Vogtle Electric Generating Plant Southern Nuclear Operating Company, Inc.
P.O. Box 1600 Waynesboro, GA 30830 Mr. Jeffrey T. Gasser Executive Vice President Southern Nuclear Operating Company, Inc.
P.O. Box 1295 Birmingham, AL 35201-1295 Mr. Steven M. Jackson Senior Engineer - Power Supply Municipal Electric Authority of Georgia 1470 Riveredge Parkway, NW Atlanta, GA 30328-4684 Mr. Reece McAlister Executive Secretary Georgia Public Service Commission 244 Washington St., SW Atlanta, GA 30334 Mr. Harold Reheis, Director Department of Natural Resources 205 Butler Street, SE, Suite 1252 Atlanta, GA 30334 Attorney General Law Department 132 Judicial Building Atlanta, GA 30334 Mr. Laurence Bergen Oglethorpe Power Corporation 2100 East Exchange Place P.O. Box 1349 Tucker, GA 30085-1349 Arthur H. Domby, Esquire Troutman Sanders NationsBank Plaza 600 Peachtree Street, NE Suite 5200 Atlanta, GA 30308-2216 Resident Inspector Vogtle Plant 8805 River Road Waynesboro, GA 30830 Office of the County Commissioner Burke County Commission Waynesboro, GA 30830
MARCH 28, 2005 CONFERENCE CALL
SUMMARY
STEAM GENERATOR TUBE INSPECTIONS VOGTLE ELECTRIC GENERATING STATION (VOGTLE), UNIT 1 DOCKET NO. 50-424 On March 28, 2005, the Nuclear Regulatory Commission (NRC) staff participated in a conference call with Vogtle, Unit 1 representatives regarding its steam generator (SG) tube inspections (particularly the finding of crack-like indications in the portion of tube confined within the tubesheet). A summary of the information discussed during the call is provided below.
Vogtle, Unit 1 has four model F SGs designed and fabricated by Westinghouse. The thermally treated Alloy 600 SG tubes have an outside diameter of 0.688-inch and a nominal wall thickness of 0.040-inch. The tubes are hydraulically expanded for the full depth of the tubesheet at each end and are supported by a number of stainless steel tube supports. In the U-bend region, the tubes are supported by anti-vibration bars. The tubes are arranged in a square pitch.
During the 2005 outage, tube inspections were planned for SGs 1 and 4. In the tubesheet region, a rotating probe equipped with a +PointTM coil was to be used to inspect the expansion transition region (from 3 inches above to 10 inches below the secondary face of the tubesheet) of 20 percent of the tubes. During this initial sample, circumferential indications initiating from the inside diameter of the tube were found in two of the tubes in SG 4. The indications were associated with bulges or over expansions. At Vogtle, a bulge is recorded at a certain location if the voltage of the bulge exceeds a threshold value (e.g., 18 volts). Similarly, a location is classified as overexpanded if the diameter of the bulged area exceeds the average diameter of the tube by a specified amount.
One of the affected tubes is located at Row 11 Column 88 (R11C88). In this tube, two circumferential indications were identified in a 170-volt bulge. The two indications were separated by approximately 170 degrees. The indications were confirmed to be present with a
+PointTM coil, a Ghent probe (a transmit-receive probe), and a delta probe (a rotating probe with 3 coils). The indications are approximately 1.7 inches below the secondary face of the tubesheet, and the voltage associated with these indications is 0.72 volts. During the last inspection of this tube in 2002, there were no indications at this location.
The other affected tube is located at R6C101. In this tube, one circumferential indication was identified in a 109-volt bulge. The indication was confirmed to be present with a +PointTM coil, a Ghent probe (a transmit-receive probe), and a delta probe (a rotating probe with 3 coils). The indication is approximately 0.4 inches below the secondary face of the tubesheet, and the voltage associated with this indication is 0.7 volts. During the last inspection of this tube in 1999, there were no indications at this location.
As a result of the findings in SG 4, the scope of the rotating probe examinations in the tubesheet region was increased. In SG 4, 100 percent of the bulges and overexpanded tubes throughout the depth of the tubesheet will be inspected. In SGs 1, 2 and 3, a 20 percent sample of all the bulges and over expansions in the tubesheet region will be inspected. These exams will be performed in the upper region (i.e., top 10 inches) of the tubesheet and on the more severe bulges and over expansions. If a crack-like indication is detected in this sample, the examinations in the affected SG will be expanded to include a 100 percent of the bulges and over expansions throughout the depth of the tubesheet.
The number of tubes with bulges and over expansions in each of the SGs was estimated as follows: 201 in SG 1, 446 in SG 2, 123 in SG 3, 177 in SG 4.
At the end of the call, the NRC staff asked to be notified if any additional crack-like indications were identified. The NRC staff did not identify any issues associated with the licensees planned inspections to address the finding of crack-like indications in bulged and overexpanded tubes in the tubesheet region.