ML12290A853

Request for Additional Information for the Review of the Limerick Generating Station, Units 1 and 2, License Renewal Application

ML12290A853
Person / Time
Site:	Limerick
Issue date:	10/19/2012
From:	Milano P License Renewal Projects Branch 1
To:	Gallagher M Exelon Generation Co
Milano P, 415-1457
References
TAC ME6555, TAC ME6556
Download: ML12290A853 (6)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 19, 2012 Mr. Michael P. Gallagher Vice President, License Renewal Projects Exelon Generation Company, LLC 200 Exelon Way Kennett Square, PA 19348

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE LIMERICK GENERATING STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC NOS. ME6555 AND ME6556)

Dear Mr. Gallagher:

By letter dated June 22, 2011, Exelon Generation Company, LLC (applicant) submitted an application, pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew the operating licenses for Limerick Generating Station, Units 1 and 2, for review by the U.S. Nuclear Regulatory Commission (NRC). On July 31,2012, the staff issued the Safety Evaluation Report with Open Items related to this application, which includes Open Item 3.0.3.2.13-1 regarding the applicant's proposed aging management of the suppression pool liner and downcomers under the scope of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, Subsection IWE. In a letter dated September 12,2012, the applicant responded to the open item.

The staff is reviewing the information contained in the letter of September 12, 2012, and has identified that further information is needed to complete its review. The specific questions are in the enclosed request for additional information (RAI).

The RAI was discussed with Christopher Wilson, and a mutually agreeable date for the response is within 15 days from the date of this letter. If you have any questions, please contact me by telephone at (301) 415-1457 or bye-mail at Patrick.Milano@nrc.gov.

Sincerely,

~~Q).~

Patrick D. Milano, Sr. Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-352 and 50-353

Enclosure:

Request for Additional Information cc w/encl: Listserv

LIMERICK GENERATING STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION REQUEST FOR ADDITIONAL INFORMATION License Renewal Application (LRA), Section B.2.1.30, "ASME Section XI, Subsection IWE" Request for Additional Information (RAI) 8.2.1.30-2.2

Background

In its response to RAI B.2.1.30-2.1, dated April 27, 2012, Exelon Generation Company, LLC (the applicant) stated that:

"[T]he acceptance criterion for the downcomers of 0.0625 inches for surface defects is applied to local degradation of less than or equal to 5.5 inches in any direction. An area of localized corrosion of 0.040 inches (or more) metal loss will be recoated. The criterion for acceptable general corrosion is less than or equal to 0.044 inches metal loss. An area greater than 5.5 inches in any direction with a depth of 0.030 inches (or more) metal loss will be recoated.

The applicant, in a letter dated September 12, 2012, stated that downcomer recoating acceptance criteria, as described in its letter dated April 27, 2012, will be incorporated into the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)

Section XI, Subsection IWE aging management program (AMP). However, the applicant revised ASME Section XI, Subsection IWE AMP B.2.1.30, LRA Appendix A, Updated Final Safety Analysis Report (UFSAR) Supplement (Section A.2.1.30 and Commitment 30) to state that ASME Section XI, Subsection IWE AMP will be enhanced prior to period of extended operation (PEO) "to include the criteria used to determine when the downcomer areas affected by corrosion will be recoated."

The applicant has not incorporated the downcomer recoating criteria, which was described in its letter dated April 27,2012, into ASME Section XI, Subsection IWE AMP submitted to the NRC on September 12, 2012. In addition, LRA Appendix A, UFSAR Supplement (Section A.2.1.30 and Commitment 30) does not describe the downcomer recoating criteria. This is not consistent with Title 10 of the Code of Federal Regulations (10 CFR) 54.21 (d), which requires that the FSAR supplement for the facility must contain a summary description of the programs and activities for managing the effects of aging for the PEO.

In its letter dated September 12, 2012, the applicant stated that the Coating Maintenance Plan, which addresses recoating the areas of general and local corrosion of the liner plate, began in 2012 to allow the prioritized actions to be implemented prior to reaching PEO. However, it is not clear to the staff why the enhancement for the downcomer inspection and recoating criteria will not be implemented (as a part of the Coating Maintenance Plan) until the PEO starts for Unit 1 in 2024 and for Unit 2 in 2029.

ENCLOSURE

- 2 Request Revise ASME Section XI, Subsection IWE AMP B.2.1.30, LRA Appendix A, UFSAR Supplement (Section A.2.1.30 and Commitment 30) to incorporate the downcomer recoating criteria. In addition, explain why prioritized actions to implement the downcomer recoating criteria are not planned prior to the PEO.

RAI 8.2.1.30-6

Background

In its letter dated September 12, 2012, the applicant stated that ultrasonic (UT) thickness measurements were performed on four liner plates in areas affected by general corrosion to determine the remaining wall thickness (two readings per plate). The thickness of these four plates was also visually assessed and compared to the UT measurements. It was determined from this comparison that the visual assessment of general corrosion metal loss for these four plates was conservative and correlated well with the UT measurements. The applicant further stated that to confirm visual assessments of general corrosion, a UT measurement will be performed, when IWE examinations are conducted, on any area of the submerged suppression pool liner affected by corrosion and significant metal loss.

The staff is concerned that a UT examination only on an area of suppression pool liner affected by general corrosion during each IWE inspection period (four years) may not be sufficient to conclude that visual assessment of general corrosion metal loss correlates well with the UT measurement.

Request Provide the justification for not performing UT examinations on a number of plates at more than one location to determine the correlation between visual assessments of general corrosion metal loss and the UT measurements.

RAI 8.2.1.30-7

Background

In its letter dated September 12, 2012, the applicant stated that the Limerick Generating Station acceptance criteria and examination methodology are consistent with ASME Section XI, Subsection IWE (specifically with the Subsections IWE -1241 and IWE-1242) and Table IWE 2500-1 requirement that 100 percent of areas having substantial corrosion require augmented inspection. Substantial liner corrosion is defined by the applicant as general corrosion that exhibits greater than 25 mils of average metal loss, or local areas of general corrosion with greater than 50 mils of metal loss. The applicant further stated that VT-1 detailed visual examinations are performed as required by ASME Section XI, Subsection IWE, Table IWE-2500-1 and 10 CFR 50.55a requirements.

-3 The staff reviewed the applicant's revised ASME Section XI, Subsection IWE AMP and UFSAR Supplement (Section A.2.1.30 and Commitment 30) provided in the letter dated September 12, 2012. The staff did not find any reference to the applicant's (owner's) defined criteria for augmented inspection as general corrosion greater than 25 mils average metal loss or local areas of general corrosion greater than 50 mil loss in the LRA AMP 8.2.1.30 and the UFSAR Supplement (Section A.2.1.30 and Commitment 30). Section CFR 54.21 (d) of 10 CFR requires that the FSAR Supplement for a facility must contain a summary description of the programs and activities for managing the effects of aging for the PEG.

Request Revise LRA AMP 8.2.1.30 and the UFSAR Supplement (Section A.2.1.30 and Commitment 30) to include owner's defined criteria for augmented inspection.

ML12290A853

• via email OFFICE PM:RPB1:DLR NAME PMilano IKing SB:DLR BC:RPB1 :DLR PM: RPB1 :DLR MMarshali DMorey PMilano DATE 10/19/2012 10/19/2012 10/19/2012 10/19/2012 10/19/2012

Letter to M. Gallagher from P Milano dated October 19, 2012

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE LIMERICK GENERATING STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC NOS. ME6555 AND ME6556)

DISTRIBUTION:

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