ML12286A067

Request for Additional Information, Review of Results of 2011 Steam Generator Tube Inspections Performed During Refueling Outage 18

ML12286A067
Person / Time
Site:	Callaway
Issue date:	10/18/2012
From:	Lyon C Plant Licensing Branch IV
To:	Heflin A Union Electric Co
Lyon C
References
TAC ME9087
Download: ML12286A067 (3)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 18, 2012 Mr. Adam C. Heflin Senior Vice President and Chief Nuclear Officer Union Electric Company P.O. Box 620 Fulton, MO 65251

SUBJECT:

CALLAWAY PLANT, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RE: 2011 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. ME9087)

Dear Mr. Heflin:

By letter dated May 17, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12139A275), Union Electric Company (the licensee) submitted information summarizing the steam generator tube inspections performed at Callaway Plant, Unit 1, during Refueling Outage 18 in 2011. The U.S. Nuclear Regulatory Commission (NRC) staff is currently reviewing the submittal to ensure compliance with Callaway Plant Technical Specification 5.6.10.

The NRC staff has determined that additional information, as requested in the enclosure, is needed to complete its review. Please provide a response to the questions within 30 days of the date of this letter.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for NRC staff review and contribute toward the NRC's goal of efficient and effective use of NRC staff resources. If circumstances result in the need to revise the requested response date, please contact me at 301-415-2296 or via e-mail at Fred.Lyon@nrc.gov.

Sincerely, Carl F. Lyon, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-483

Enclosure:

As stated cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION 2011 STEAM GENERATOR TUBE INSPECTIONS UNION ELECTRIC COMPANY CALLAWAY PLANT, UNIT 1 DOCKET NO. 50-483 By letter dated May 17, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12139A275), Union Electric Company (the licensee) submitted information summarizing the steam generator (SG) tube inspections performed at Callaway Plant, Unit 1, during Refueling Outage 18 in 2011. The U.S. Nuclear Regulatory Commission (NRC) staff is currently reviewing the submittal to ensure compliance with Callaway Plant Technical Specification 5.6.10. The NRC staff has determined that additional information is needed to complete its review. Please provide a response that addresses the questions below.

1. Please discuss the results of your plug inspection. Regarding the secondary side inspections in the steam drum area of SG Band SG C, please discuss whether any degradation was identified.

2. On page 2 of the report, it is indicated that the X-probe was used to acquire data on both the hot-leg and cold-leg from the tube end to 1-inch above the first tube support plate, in all four SGs. The report also states that the data would be analyzed for both hot-leg and cold-leg, from 3-inches below the top of the tubesheet to 1-inch above the first support plate. Table 1 on page 3, however, indicates that only the hot-leg data was analyzed and that only data from 3 inches above to 3 inches below the top of the tubesheet was acquired. Please clarify.

3. Please provide descriptions of the following acronyms: IDC and SPT.

4. For the 20 percent random sample of dings that were performed on each SG, please provide the minimum voltage threshold used for screening.

5. Please clarify the nature of the 33 miss-drilled tubes (e.g., size, location).

6. The text below Table 3 indicates that the maximum reported axial length was 0.59 inches and the maximum reported circumferential extent was 48 degrees. Please verify these numbers, as Table 3 is noted to contain an axial length and circumferential extent greater than these values.

7. Table 3 provides a listing of tube support plate wear indications; please provide a similar table for all anti-vibration bar indications.

8. There appears to be a Significant increase in the number of wear indications at the tube supports and anti-vibration bars. Please discuss any insights for these increases. Please discuss whether the growth rates of these indications have increased or decreased.

Enclosure

' ML12286A067 *email dated October 5 , 2012 OFFICE NRR/LPL4/PM NRR/LPL4/LA NRRlDE/ESGB/BC NRRlLPL4/BC NRR/LPL4/PM NAME FLyon JBurkhardt GKulesa' MMarkley FLyon (LGibson for)

DATE 10/17/12 10/17/12 10/5112 10/18/12 10/18/12