ML120170140

E-mail, Request for Additional Information 1RE16 Steam Generator Tube Inspection Summary Report

ML120170140
Person / Time
Site:	South Texas
Issue date:	01/17/2012
From:	Balwant Singal Plant Licensing Branch IV
To:	Harrison A South Texas
Singal, Balwant, 415-3016, NRR/DORL/LPL4
References
TAC ME7266
Download: ML120170140 (2)

Text

From: Singal, Balwant Sent: Tuesday, January 17, 2012 9:51 AM To: Harrison, Albon Cc: Walker, Harold

Subject:

South Texas Project, Unit 1 1RE16 Steam Generator Tubing Inspection Summary Report - Request for Additional Information (RAI)

By letter dated September 21, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML11272A126), South Texas Project Nuclear Operating Company (the licensee), submitted information summarizing the results of the spring 2011 steam generator tube inspections at South Texas Project Unit 1. In order to complete its review of this document the Nuclear Regulatory Commission (NRC) staff requests the following additional information:

1. In Table 1, 12 tubes were identified as requiring a retest due to a restriction. Please discuss the nature and cause of these restrictions. Please also address if these restrictions were service induced?

2. Table 5 lists the visual inspection results for the top of tubesheet potential loose part signals. For steam generator D, 6 possible loose part signals were identified at the top of the tubesheet; however, only 5 are listed in Table 5. Was a visual inspection performed for the sixth possible loose part signal at the top of the tubesheet. If so, please discuss the results.

3. Please discuss whether any visual inspections were performed in steam generator D for the 89 possible loose part signals located at the flow distribution baffle and 1st tube support plate. If visual inspections were performed, please discuss the results. Were these possible loose part signals present in prior outages?

4. Inspections of the steam drums were performed in two steam generators. Please discuss the results of these inspections. In addition, please discuss the results of the video inspection of the ninth tube support plate in steam generator 1A.

5. It was indicated that signals representative of tube diameter increases (bulges) were reported from the bobbin inspection analyses. Please discuss the nature of these bulges. Are these indications service induced? Please discuss how these indications were dispositioned.

6. Page 3 The following paragraph is on page 3:

Within the noise of the bobbin data is a very small signal measuring approximately 4%. The signals are very much like the residual on each edge of the TSP. For the 1RE16 inspection, the overall noise was less, the mix residual a little less, and the signal was therefore more defined from its surroundings. Wear at TSP is considered a "potential degradation mechanism" for the RSG's within the 1RE16 Degradation Assessment.

Please clarify the context of this paragraph. Is it describing general trends in the eddy current data or results from a specific tube? If so, which tube has the 4% through-wall

indication since none of the flaws identified in the submittal have a reported depth of 4%

through-wall.

A copy of the Draft RAI was issued via e-mail on January 3, 2012. Mr. Philip Walker informed us on January 16, 2012 that no clarification call is needed. Please treat these RAIs a s formal RAIs. You are requested to respond to these RAIs within 30 days from the date of this e-mail.

Thanks.

Balwant K. Singal Senior Project Manager (Comanche Peak, STP, and Palo Verde)

Nuclear Regulatory Commission Division of Operating Reactor Licensing Balwant.Singal@nrc.gov Tel: (301) 415-3016 Fax: (301) 415-1222