ML073450005

E-mail from Mohan Thadani, Project Manager to Wayne Harrison and Scott Head at STPEGS

ML073450005
Person / Time
Site:	South Texas
Issue date:	12/10/2007
From:	Thadani M NRC/NRR/ADRO/DORL/LPLIV
To:	Harrison A, Head S South Texas
Thadani, M C, NRR/DORL/LP4, 415-1476
References
TAC MD5948
Download: ML073450005 (4)

Text

From: Mohan Thadani To: INTERNET:awharrison@stpegs.com; Internet:smhead@stpegs.com Date: 12/10/2007 3:54:20 PM

Subject:

PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION RE: UNIT 1 SG TUBE INSPECTIONS Scott/Wayne:

By letter dated April 16, 2007, (ML071140087) STP Nuclear Operating Company submitted information summarizing the results of the steam generator tube inspections performed at STP Unit 1 during its Fall 2006 refueling outage (1RE13).

In order for the U.S. Nuclear Regulatory Commission staff to complete its review of the submitted information, please address the following request for additional information. Please let me know the date by which you could forward a response to the following RAI.

I will arrange a phone call to discuss the RAI, if clarification is needed.

Thank you for your support.

Mohan 301 415-1476 SOUTH TEXAS PROJECT UNIT 1 2006 STEAM GENERATOR INSPECTIONS REQUEST FOR ADDITIONAL INFORMATION DOCKET NO. 50-498 (TAC MD5948)

1. You state that one tube in Steam Generator (SG) D was plugged (R117 C49) due to a wear depth of 44% at the top of tubesheet on the cold leg due to wear caused by the stabilizer wire. When was this tube last inspected and was this a location where a loose part was present during the prior inspection?

2. Please describe the inspection techniques used to perform the upper steam drum, feedring and ninth tube support plate inspections; were they visual or ultrasonic?

Please discuss the results of these inspections.

3. For each RFO or SG tube inspection since installation of the replacement SGs, please provide the cumulative effective full power months that the SGs have operated.

4. Please clarify the following sentence: AA more extensive eddy current and visual inspection of steam generator 1D was developed to support the planned 3 cycle inspection interval for the Unit 1 steam generators.@ Is this statement intended to indicate that a more robust examination was performed in steam generator 1D in an effort to justify extending the interval between inspections from 1 cycle to 3 cycles?

5. Please clarify the following sentence: A+Point inspection of 20% of the first two rows of U-bend lookingY..@ Were these tubes inspected full length with a +Point coil or was only the U-bend region of 20%

of the row 1 and 2 tubes inspected with a +Point coil?

6. For steam generators 1A, 1B, and 1C, a +Point inspection of all tube bulges in the tubesheet were performed. For steam generator 1D a +Point inspection of all tube bulges and overexpansions in the tubesheet was performed. Please discuss why the overexpansions in steam generators 1A, 1B, and 1C were not inspected.

7. For steam generators 1A, 1B, and 1C, it was indicated that an eddy current inspection would be performed on tubes near unretrieved possible loose parts, if possible.

Please clarify why it may not be possible to inspect these tubes. If these tubes are not inspectable, please discuss why these tubes were not plugged and how you confirmed (or will confirm) that these tubes have adequate integrity.

8. Please discuss the results of the tube scale profiling performed in steam generator 1C.

9. Regarding the table summarizing the scope of your eddy current inspections, please clarify the following:

a. Please clarify the hot- and cold-leg columns. Do the numbers in these columns indicate the number of tubes that were inspected from either the hot or cold leg. For example, were 4330 tubes in steam generator 1A inspected full length from the hot leg, and an additional 384 tubes inspected full length from the cold leg?

b. There appears to be a disproportionate number of dents/dings in steam generator 1A. Please clarify.

c. Please clarify the APLPs [possible loose parts] Inspected@ and APLP Calls@ rows. If there were no PLP Calls, why were any PLPs inspected?

10. Please confirm that no wear was found at the tube support plate elevations.

11. Regarding the PLP indications, please discuss the extent to which these

indications were found during the bobbin, rotating probe, or both inspections (i.e., provide the number of indications detected with only the bobbin probe, the number of indications detected with only the rotating probe, and the number of indications detected with both probes).

12. Regarding the visual inspections at the top of the tubesheet and at the flow distribution baffle in steam generator 1D, please address the following: (a) the source of the PLP indications at the flow distribution baffle, (b) the number of loose parts/foreign object left in steam generator 1D at the top of the tubesheet and the flow distribution baffle including their location and size. How much stabilizer wire remains unaccounted for in the SGs?

13. Please discuss the nature of the restriction in the one tube in steam generator 1B.

14. In the Table on page 7 there are several locations/tubes that were listed as Aretest@ tubes. Please confirm that all of these tubes/locations were

15. In several instances, you discuss Aactive degradation mechanisms.@ In the context of this report, please confirm that Aactive degradation mechanism@ is referring to any service-induced deterioration of the tubes due to mechanical wear or corrosion (regardless of the depth of the deterioration).

CC: Burke, John; Hiltz, Thomas; Hiser, Allen; Karwoski, Kenneth Mail Envelope Properties (475DA77C.BC4 : 23 : 35106)

Subject:

PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION RE:

UNIT 1 SG TUBE INSPECTIONS Creation Date 12/10/2007 3:54:20 PM From: Mohan Thadani Created By: MCT@nrc.gov

Recipients nrc.gov OWGWPO01.HQGWDO01 JPB3 CC (John Burke) nrc.gov OWGWPO04.HQGWDO01 ALH1 CC (Allen Hiser)

KJK1 CC (Kenneth Karwoski)

TGH CC (Thomas Hiltz)

STPEGS.COM awharrison (INTERNET:awharrison@stpegs.com) smhead (Internet:smhead@stpegs.com)

Post Office Route OWGWPO01.HQGWDO01 nrc.gov OWGWPO04.HQGWDO01 nrc.gov STPEGS.COM Files Size Date & Time MESSAGE 9322 12/10/2007 3:54:20 PM Options Expiration Date: None Priority: Standard ReplyRequested: No Return Notification: None Concealed

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