ML102360292

Summary of Teleconference Regarding 2009 SG Tube Inspections at Palisades Nuclear Plant

ML102360292
Person / Time
Site:	Palisades
Issue date:	08/30/2010
From:	Mahesh Chawla Plant Licensing Branch III
To:	Entergy Operations
Chawla M, NRR/DORL, 415-8371
References
TAC ME2475
Download: ML102360292 (3)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 Augus t 30, 2010 Vice President, Operations Entergy Nuclear Operations, Inc.

Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043-9530

SUMMARY

OF TELECONFERENCE REGARDING 2009 STEAM GENERATOR TUBE INSPECTIONS AT PALISADES NUCLEAR PLANT (TAC NO. ME2475)

Dear Sir:

By letter dated October 22, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML092950525), Entergy Nuclear Operations, Inc. (the licensee) submitted information pertaining to their 2009 steam generator (SG) tube inspections at the Palisades Nuclear Plant. The licensee provided additional information regarding the SG inspections in a letter dated June 22, 2010 (ADAMS Accession Number ML101730490). The U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call held with the licensee, concerning the 2009 SG tube inspections, in a letter dated May 7,2009 (ADAMS Accession Number ML091060762).

The NRC staff has completed its review of these reports and concludes that the licensee provided the information required by their technical specifications and that no additional follow up is required at this time. The staff's review of the reports is enclosed.

If you have any questions regarding this matter, I may be reached at 301-415-8371.

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Mahesh Chawla, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-255 cc w/encl: Distribution via ListServ

REVIEW OF THE 2009 STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT PALISADES NUCLEAR PLANT DOCKET NUMBER 50-255 By letter dated October 22, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML092950525), Entergy Nuclear Operations, Inc. (the licensee) submitted information pertaining to their 2009 steam generator (SG) tube inspections at the Palisades Nuclear Plant. The licensee provided additional information regarding the SG inspections in a letter dated June 22, 2010 (Accession Number ML101730490).

The U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call held with the licensee, concerning the 2009 SG tube inspections, in a letter dated May 7,2009 (Accession Number ML091060762).

Palisades Nuclear Plant has two Combustion Engineering Model 2530 replacement SGs. Each SG has 8,219 mill-annealed, Alloy 600 tubes. The tubes have an outside diameter of 0.75 inches, and a wall thickness of 0.042 inches. The tubes were expanded through the full depth of the tubesheet using an explosive process.

The licensee provided the scope, extent, methods, and results of their steam generator tube inspections in the documents referenced above. In addition, the licensee described corrective actions (e.g., tube plugging) taken in response to the inspection findings.

After review of the information provided by the licensee, the NRC staff has the following comments/observations:

The licensee observed cracking in the portion of the tubes within the tubesheet, at the top of the tubesheet, in the freespan (associated with dings), at eggcrate supports, at vertical straps, and in the u-bend.

The cracks at the dings were identified with the bobbin and rotating probe. The voltage for one of the dings was approximately 2.1 volts.

One of the axially oriented stress corrosion cracks grew from non-detectable to a size that warranted in-situ pressure testing. The tube (in row 72, column 107 of SG B) passed the in-situ pressure test, and no leakage was observed at a test pressure of 5500 pounds per square inch. This flaw was only identified by one of the two analysts that reviewed the 2009 eddy current data. The reason why the other analyst did not identify this flaw was not provided. The NRC staff also reviewed the 2009 eddy current data from this flaw and concluded that there was a detectable bobbin coil signal on both the differential mix channel as well as the absolute mix channel. The staff estimated the flaw penetrated approximately 40- to 50-percent of the wall thickness.

Based on a review of the information provided by the licensee, the staff concludes that the licensee provided the information required by their technical specifications. The SG tube inspections at Palisades Nuclear Plant appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

ENCLOSURE

ML102360292 *Memo dated July 9, 2010 from RT I t0 R PascareII'I avior OFFICE NRR/LPL3-1/PM NRR/LPL3-1/LA NRR/CSGB/BC* NRR/LPL3-1/BC NAME MChawla BTuily RTaylor RPascarelli /PTam for DATE 08/30/10 08/27/10 07/09/10 08/30/10