ML112930436

Review of the 2011 Steam Generator Tube Inspections

ML112930436
Person / Time
Site:	Calvert Cliffs
Issue date:	10/27/2011
From:	Pickett D Plant Licensing Branch 1
To:	George Gellrich Calvert Cliffs
Pickett D, NRR/DORL/LPL1-1, 415-1364
References
TAC ME6672
Download: ML112930436 (4)

Text

UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555-0001 October 27, 2011 Mr. George H. Gellrich, Vice President Calvert Cliffs Nuclear Power Plant, LLC Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702 CALVERT CLIFFS NUCLEAR POWER PLANT UNIT NO.2 -REVIEW OF THE 2011 STEAM GENERATOR TUBE,INSPECTIONS (TAC NO. ME6672)

Dear Mr. Gellrich:

By letter dated June 30, 2011, Calvert Cliffs Nuclear Power Plant, LLC, the licensee, submitted information summarizing the results of the 2011 steam generator (SG) tube inspections performed at the Calvert Cliffs Nuclear Power Plant Unit No.2. The Nuclear Regulatory Commission (NRC) staff has completed its review of this report. Based on its review, the staff concludes that the licensee provided the information required by the plant's technical specifications.

In addition, the staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and that inspection results appear to be consistent with industry operating experience at similarly designed and operated units. The NRC staff's review of this report is enclosed.

Please feel free to contact me at 1364 if you have any questions.

Sincerely, Douglas V. Pickett, Senior Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-318

Enclosure:

As stated cc w/encl: Distribution via Listserv UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CALVERT CLIFFS NUCLEAR POWER PLANT. LLC REVIEW OF THE 2011 STEAM GENERATOR TUBE INSPECTIONS CALVERT CLIFFS NUCLEAR POWER PLANT UNIT NO.2 DOCKET NUMBER 50-318 By letter dated June 30, 2011 (Agencywide Documents Access Management System Accession No. ML111822717), Calvert Cliffs Nuclear Power Plant, LLC, the licensee, submitted information summarizing the results of the 2011 steam generator (SG) tube inspections performed at Calvert Cliffs Nuclear Power Plant Unit No.2 (Calvert Cliffs Unit 2). Calvert Cliffs Unit 2 has two Babcock and Wilcox International SGs. Each SG contains 8471 thermally-treated Alloy 690 tubes. Each tube has a nominal outside diameter of 0.75 inches and a nominal wall thickness of 0.042 inches. The SGs have a triangular tube pitch arrangement with 1 inch spacing between tube centers. The tubes are hydraulically expanded the entire depth of the tubesheet.

Rows 1-18 of the U-bend received stress relief treatment after bending. The licensee provided the scope, extent, methods, and results of their SG tube inspections in the document referenced above. In addition, the licensee described corrective actions, such as tube plugging, taken in response to the inspection findings. The tubes in SGs 21 and 22 were inspected this outage. After reviewing the information provided by the licensee, the staff has the following comments or observations: The licensee reported that all plugs were visually inspected and confirmed to be in the proper location with no evidence of deformation or leakage. The licensee reported that the 1 st lattice support was visually inspected with views looking upward at the bottom of the 1 st lattice support showing mostly clean conditions, with an occasional flake wedged between the tubes and the lattice bars. The tube surfaces had a fairly uniform thin film of deposit but looked clean. The licensee reported that all lattice support and shroud support components appeared structurally sound and in good condition.

In addition, the shroud support bracket weldments and lattice ring backing bars were observed and found to be in good condition.

It was also reported that the annular region of the 1 st lattice support was viewed and all structural components such as shroud support lugs were found to be sound and intact. The horizontal surfaces Enclosure

-2 in the annular region were characterized as being uniformly coated with a thin, dark gray colored film deposit. The licensee also reported that the materials for the lattice, lattice assembly, bolts, and the support structures appeared as manufactured with no degradation. The licensee reported 343 Potential Loose Part (PLP) indications in SG 21, and 203 were recorded in SG 22. Of the 343 PLP indications in SG 21, 92 of them were classified as inner bundle single (IBS) indications.

In addition, of the 203 PLP indications detected in SG 22, 69 of them were classified as IBS indications.

The licensee stated that I BS indications are defined as PLP indications located in a single tube without a PLP indication in an adjacent bounding tube. The licensee indicated that most of the PLPs were caused by sludge rocks and/or scale. The licensee indicated that during the 2011 refueling outage, the only metallic objects identified and remaining in the Calvert Cliffs Unit 2 SGs are three pieces of wire plus a small shear pin (1/32" diameter by 1/16" length) in SG 22 and two other smaller metallic objects in SG 21 (machining curl and a piece of wire). The licensee also identified non-metallic objects (primarily sludge rocks, flakes, gasket material, etc.) that remain in the SGs. It was reported that historical metallic objects continue to remain in the SGs from previous outages. These objects were addressed and dispositioned at the time. The disposition either allowed the object to remain in-place or required associated tubes to be plugged and/or stabilized. The licensee confirmed that a bounding analysis was performed on the objects newly identified during the Unit 22011 refueling outage. The licensee stated that the results of this analysis concluded that a complete through-wall wear scar or indication in the tube outer diameter is not probable over the next two fuel cycles or four effective full power years. Furthermore, it was indicated that the analysis previously performed in support of historical metallic objects continues to remain in effect, where applicable.

Based on a review of the information provided, the staff concludes that the licensee provided the information required by the technical specifications.

In addition, the staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and that inspection results appear to be consistent with industry operating experience at similarly designed and operated units. Principal Contributor:

A. Obodoako, NRR Date: October 27, 2011 October 27, 2011 Mr. George H. Gellrich, Vice President Calvert Cliffs Nuclear Power Plant, LLC Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702 CALVERT CLIFFS NUCLEAR POWER PLANT UNIT NO.2 -REVIEW OF THE 2011 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. ME6672)

Dear Mr. Gellrich:

By letter dated June 30, 2011, Calvert Cliffs Nuclear Power Plant, LLC, the licensee, submitted information summarizing the results of the 2011 steam generator (SG) tube inspections performed at the Calvert Cliffs Nuclear Power Plant Unit No.2. The Nuclear Regulatory Commission (NRC) staff has completed its review of this report. Based on its review, the staff concludes that the licensee provided the information required by the plant's technical specifications.

In addition, the staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and that inspection results appear to be consistent with industry operating experience at similarly designed and operated units. The NRC staff's review of this report is enclosed.

Please feel free to contact me at 1364 if you have any questions.

Sincerely, Ira! Douglas V. Pickett, Senior Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-318

Enclosure:

As stated cc w/encl: Distribution via Listserv DISTRIBUTION:

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