ML13009A158

Review of the Spring 2011 Steam Generator Tube Inservice Inspections During Refueling Outage 17

ML13009A158
Person / Time
Site:	Byron
Issue date:	01/17/2013
From:	Joel Wiebe Plant Licensing Branch III
To:	Pacilio J Exelon Generation Co
Joel Wiebe, NRR/DORL 415-6606
References
TAC ME9452
Download: ML13009A158 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 17, 2013 Mr. Michael J. Pacilio Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO)

Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BYRON NUCLEAR POWER STATION, UNIT 1 - REVIEW OF THE SPRING 2011 STEAM GENERATOR TUBE INSERVICE INSPECTIONS DURING REFUELING OUTAGE 17 (TAC NO. ME9452)

Dear Mr. Pacilio:

By letter dated July 14,2011 (Agencywide Documents Access Management Systems (ADAMS)

Accession No. ML11200A302), Exelon Generation Company, LLC (the licensee) submitted information summarizing the results of their 2011 steam generator tube inspections performed during refueling outage 17 at Byron Nuclear Power Station, Unit 1 (Byron 1).

The NRC staff has completed its review of the report and concludes that the licensee provided the information required by the Byron 1 technical specifications. No additional follow-up is required at this time. The NRC staff's review is enclosed.

If you have any questions regarding the enclosure, please contact me at (301) 415-6606.

Sincerely,

' bV~

~ oel S. Wiebe, Senior Project Manager lant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-454

Enclosure:

Summary of NRC Staff Review cc w/encl: Listserv

SUMMARY

OF NRC STAFF REVIEW OF THE STEAM GENERATOR TUBE INSERVICE INSPECTION FOR REFUELING OUTAGE 17 BYRON NUCLEAR POWER STATION, UNIT NO.1 DOCKET NO. STN 50-454 By letter dated July 14, 2011 (Agencywide Documents Access Management System (ADAMS)

Accession No. ML11200A302), Exelon Generation Company, LLC ( the licensee) submitted information summarizing the results of their 2011 steam generator (SG) tube inspections performed during refueling outage 17 at Byron Nuclear Power Station, Unit No.1 (Byron 1).

Byron 1 has four Babcock & Wilcox SGs. Each SG contains 6,633 thermally treated Alloy 690 tubes. Each tube has a nominal wall thickness of 0.040 inches. The tubes were hydraulically expanded at both ends for the full length of the tubesheet and are supported by a number of stainless steel lattice grid structures and fan bars.

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 (Le., tube plugging) taken in response to the inspection findings. All the tubes in the four SGs were inspected during this outage.

After reviewing the information provided by the licensee, the staff has the following co m ments/observations:

• The licensee reported that during the steam drum inspection, erosion was found in the steam nozzle venturi area. The localized degradation was observed in the material surrounding the venturi, adjacent to the retaining plate. The licensee stated that the original equipment manufacturer was contacted regarding this degradation and concluded to accept the condition "as-is" and that there are no further actions required.

The licensee based their conclusion on the fact that the venturies are held in place primarily by an interface fit between the venturi and steam nozzle, the retaining plate only provides a secondary retaining function, and localized degradation of the base material will in no way affect the function of the venturies or increase the risk of the venturies loosening during operation.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by the Byron 1 technical specifications. In addition, the NRC 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 the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

Primary Contributor: A. Obodoako Enclosure

ML13009A158 OFFICE LPL3-2/PM LPL3-2/LA LPL3-2/BC LPL3-2/PM NAME JWiebe SRohrer MDudek JWiebe DATE 01 110/13 01/10/13 01/16/13 01/17/13