ML082810446

Request for Additional 180-Day Report on the Sprung 2008 Steam Generator Tube Inspection-Calvert Cliffs Nuclear Power Plant, Unit No. 1

ML082810446
Person / Time
Site:	Calvert Cliffs
Issue date:	10/15/2008
From:	Pickett D Plant Licensing Branch 1
To:	Spina J Calvert Cliffs
pickett , NRR/DORL, 415-1364
References
TAC MD9446
Download: ML082810446 (3)

Text

October 15, 2008 Mr. James A. Spina, Vice President Calvert Cliffs Nuclear Power Plant, Inc.

Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RE: 180-DAY REPORT ON THE SPRING 2008 STEAM GENERATOR TUBE INSPECTION - CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NO. 1 (TAC NO. MD9446)

Dear Mr. Spina:

By letter dated July 31, 2008, Calvert Cliffs Nuclear Power Plant, Inc. submitted the 180-Day Report on the Spring 2008 Steam Generator Tube Inspection. This report documented the steam generator inspections performed at the Calvert Cliffs Nuclear Power Plant, Unit No. 1.

The NRC staff has reviewed the information provided and has determined that additional information is needed to complete its review. Enclosed is the staffs request for additional information (RAI). As discussed with your staff, we understand that you intend to respond to this RAI by December 5, 2008.

Please contact me at 301-415-1364 if you have any questions.

Sincerely,

/RA/

Douglas V. Pickett, Senior Project Manager Plant Licensing Branch I-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-317

Enclosure:

As stated cc w/encl: Distribution via ListServ

ML0828210446 OFFICE PM/LPL1-1 LA:LPL1-1 BC/CSGB BC/LPL1-1 NAME DPickett SLittle AHiser by MKowal memo dated DATE 10 /14/ 08 10 /14/ 08 9 / 25 / 08 10 /15/ 08 REQUEST FOR ADDITIONAL INFORMATION 2008 STEAM GENERATOR TUBE INSPECTIONS CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NO. 1

1. For each refueling outage since installation of the steam generators (SGs), please provide the cumulative effective full-power months that the SGs have operated.

2. In the report, it is stated that 324 fan bar wear (FBW) indications in 272 tubes were identified in the Calvert Cliffs Nuclear Power Plant Unit 1 SGs during the spring 2008 inspection; an increase of approximately 2/3 from the 189 indications in 166 tubes identified during the 2004 inspection. Please describe any insights on the cause of the increase of FBW indications. Please also describe the size distribution of the new FBW indications found in the spring 2008 inspection in comparison to the size distribution of the FBW indications found in the 2004 inspection. If the size distribution of the new indications is comparable or more severe than the size distribution of the old indications, please discuss whether the conditions are becoming worse with time. Please also discuss what tubes are considered to be in the pre-defined fan bar wear susceptible region and why it appears to differ between the two SGs.

3. Please describe the scope and results of any secondary side inspections.

4. Please discuss the nature of the ambiguous bobbin indications.

5. Presumably, a number of new bobbin indications were identified near the fan bars. Of these new bobbin indications, it does not appear that all were inspected with rotating probes and that only those indications greater than 15% through-wall were inspected with a rotating probe. If the Nuclear Regulatory Commission staffs understanding is correct, discuss how the causal mechanisms for these new bobbin indications were determined. Please discuss how wear attributed to tube-to-tube contact and loose parts was ruled out as the causal mechanism.

6. Please discuss whether any tubes were identified that were in close proximity.

7. Please provide a list of all service induced indications including their location, orientation (if linear) and measured sizes.

8. Please discuss whether a secondary side visual inspection was performed near the tubes attributed to foreign object wear (SG11 R126C114 and SG12 R106C134) to confirm the absence of a loose part. In addition, please discuss whether potential loose part indications (from the eddy current data) were visually inspected to identify and remove any loose parts. If any possible loose part indications were left in service without visual inspection, please discuss how it was confirmed that tube integrity would be maintained.

Enclosure