ML072851071

Request for Additional Information Regarding the 2006 Steam Generator Tube Inspections

ML072851071
Person / Time
Site:	Vogtle
Issue date:	10/29/2007
From:	Siva Lingam NRC/NRR/ADRO/DORL/LPLII-1
To:	Tynan T Southern Nuclear Operating Co
Martin R, NRR/DORL, 415-1493
References
TAC MD5394
Download: ML072851071 (6)

Text

October 29, 2007 Mr. Tom E. Tynan Vice President - Vogtle Vogtle Electric Generating Plant 7821 River Road Waynesboro, GA 30830

SUBJECT:

VOGTLE ELECTRIC GENERATING PLANT, UNIT 1 (VOGTLE), REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING THE 2006 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MD5394)

Dear Mr. Tynan:

By letter dated April 18, 2007, Southern Nuclear Operating Company, Inc. (the licensee),

submitted the 2006 steam generator (SG) tube inspections report performed at Vogtle 1 during the thirteenth refueling outage (1R13). The Nuclear Regulatory Commission (NRC) staff is reviewing the submittal and has determined that additional information is required to complete its evaluation.

The NRC staffs RAI is enclosed. The licensee is required to provide a response to the RAI within 30 days.

Sincerely,

/RA/

Siva P. Lingam, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-424

Enclosure:

RAI cc w/encl: See next page

ML072851071

• transmitted by memo dated OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NRR/DCI/CSGB/BC NRR/LPL2-1/BC NAME SLingam;nc MO=Brien AHiser EMarinos DATE 10 / 26 /07 10 / 26 /07 10/9/07*

10 / 29 /07

Enclosure REQUEST FOR ADDITIONAL INFORMATION REGARDING THE 2006 STEAM GENERATOR TUBE INSPECTIONS VOGTLE ELECTRIC GENERATING PLANT, UNIT 1 DOCKET NO. 50-424 By letter dated April 18, 2007 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML072480031), Southern Nuclear Operating Company, Inc.,

(the licensee), submitted information summarizing the results of the 2006 steam generator (SG) tube inspections at Vogtle Electric Generating Plant, Unit 1(Vogtle 1). These inspections were performed during the thirteenth refueling outage (1R13). In addition to this report, the Nuclear Regulatory Commission (NRC) staff summarized a conference call about the 2006 SG tube inspections at Vogtle 1 in a letter dated December 19, 2006 (ADAMS Accession No. ML063390165). In order to complete its review of the documents listed above, the NRC staff needs the following additional information:

1. The first sentence on page 4 references the tube in SG2 row 66 column 1. Considering that this tube is not referenced in the table on page 4, please clarify whether the sentence should have referenced the tube in row 6 column 1 (which is in the table).

2. Please provide the scope and results of any secondary side inspections (including foreign object search and retrieval) performed during the 2006 outage.

3. You indicated that you inspected 25% of the bulges and overexpansions from 3 inches above to 17 inches below the top of the tubesheet on the hot leg in SG1 (26 tubes), SG2 (52 tubes), and SG3 (14 tubes). In SG4, you inspected 100% (78 tubes) of the population.

Please clarify whether the total population of bulges and overexpansions in SG1, 2, and 3 are in 26, 52, and 14 tubes, respectively, or whether 25% of the bulges and overexpansions are in 26, 52, and 14 tubes, respectively.

4. Please clarify the scope of your dent and ding inspections. In particular, were all dents and dings greater than or equal to five volts on the hot-leg inspected with a rotating probe, or were just those in the u-bend examined?

5. Please provide the effective full power years (or months) for each of your inspections.

6. You indicated that 50% of the u-bends in rows one and two were inspected this outage.

Please discuss the last time the u-bends in the remaining 50% were inspected.

7. In response to oxide removal patterns in several rows, you performed rotating probe examinations of several tubes. These inspections indicated shallow wall loss, which was possibly the result of ultrasonic energy cleaning that had been used in previous outages.

Please discuss when this ultrasonic cleaning process was used and whether the

Enclosure indications of wall loss were detected with the bobbin coil (during this outage and in the outages after the ultrasonic cleaning process was applied.) If not detected with the bobbin

probe, please discuss why not, since the sizes of the indications are comparable to the sizes of wear indications reported at Vogtle 1 and other plants. In addition, if these were not detected by bobbin, discuss the possibility that these indications may be attributable to some other degradation mechanism. Please discuss the extent to which tubes other than in this row may have been affected. Please discuss the purpose of this UT cleaning process.

8. You indicated that all tubes with indications attributed to loose part wear were visually examined except for two tubes. These tubes were in row 66 column 1 (see previous question on whether this should be row 6 column 1) and row 39 column 46. If row 6 column 1 was not visually inspected, please clarify the statement that it was left in service as a result of not identifying any loose parts in inspections of tubes surrounding row 6 column 1.

9. Please discuss whether any tubes with both loose parts wear and confirmed loose parts (based on visual examination) were left in service. If so, discuss the basis for leaving these tubes in service. Please discuss the history and nature of the loose part wear indications in SG2 row 39 column 46.

10. Please discuss the extent to which the indication in SG4 row 5 column 68 extends below the bottom of the expansion transition (given that this is an OD-initiated indication, which may be isolated from the environment).

11. Please discuss the purpose of the chemical cleaning (e.g., removing deposits from within quatrefoil shaped holes) and whether it was successful.

12. You indicate that you satisfied the accident-induced leakage performance criterion since presumably only one indication was predicted to leak and this leak rate was less than your acceptance limits. Please confirm that only the single axial indication was predicted to leak. In addition, confirm that you combined this leak rate with the leak rate from other sources (e.g., plugs) in determining that you met your condition monitoring limits.

Vogtle Electric Generating Plant, Units 1 & 2 cc:

Mr. Tom E. Tynan Vice President - Vogtle Vogtle Electric Generating Plant 7821 River Road Waynesboro, GA 30830 Mr. N. J. Stringfellow Manager, Licensing Southern Nuclear Operating Company, Inc.

P.O. Box 1295 Birmingham, AL 35201-1295 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 Nations Bank 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