ML15344A354

Requests for Additional Information for the Review of the Lasalle County, Units 1 and 2 License Renewal Application Set 15

ML15344A354
Person / Time
Site:	LaSalle
Issue date:	02/16/2016
From:	Jeffrey Mitchell License Renewal Projects Branch 1
To:	Gallagher M Exelon Generation Co
Mitchell J, NRR/DLR, 415-3019
References
TAC MF5346, TAC MF5347
Download: ML15344A354 (6)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 16, 2016 Mr. Michael P. Gallagher Vice President, License Renewal Projects Exelon Generation Company, LLC 200 Exelon Way Kennett Square, PA 19348

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE LASALLE COUNTY STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION - SET 15 (TAC NOS. MF5347 AND MF5346)

Dear Mr. Gallagher:

By letter dated December 9, 2014, Exelon Generation Company, LLC (Exelon) submitted an application pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew the operating licenses NPF-11 and NPF-18 for LaSalle County Station (LSCS), Units 1 and 2, respectively. The staff of the U.S. Nuclear Regulatory Commission (NRC or the staff) is reviewing the information contained in the license renewal application and has identified, in the enclosure, areas where additional information is needed to complete the review.

These requests for additional information were discussed with Mr. John Hufnagel, and a mutually agreeable date for the response is within 30 days from the date of this letter. If you have any questions, please contact me at 301-415-3019 or by e-mail at Jeffrey.Mitchell2@nrc.gov.

Sincerely,

/RA Daneira Melendez for/

Jeffrey S. Mitchell, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374

Enclosure:

As stated cc: Listserv

ML15344A354 OFFICE LA:DLR*

PM:RPB1:DLR BC:RPB1:DLR PM:RPB1:DLR NAME YEdmonds JMitchell YDiaz-Sanabria JMitchell (DMelendez-Colon for)

DATE 2/11/16 2/11/16 2/15/16 2/16/16

Letter to Michael Gallagher from Jeffrey S. Mitchell dated February 16, 2016

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE LASALLE COUNTY STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION - SET 15 (TAC NOS. MF5347 AND MF5346)

DISTRIBUTION:

E-MAIL:

PUBLIC RidsNrrDlr Resource RidsNrrDlrRpb1 Resource RidsNrrDlrRpb2 Resource RidsNrrDlrRerb Resource RidsNrrDlrRarb Resource RidsNrrDlrRasb Resource RidsNrrDlrRsrg Resource RidsNrrPMLaSalle Resource J. Mitchell R. Plasse D. Drucker J. Danna J. Wachutka, OGC J. Lindell, OGC D. McIntyre, OPA M. Kunowski, RIII V. Mitlyng, RIII P. Chandrathil, RIII H. Logaras, RIII C. Lipa, RIII S. Sheldon, RIII R. Ruiz, RIII J. Robbins, RIII

ENCLOSURE LASALLE COUNTY STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION REQUESTS FOR ADDITIONAL INFORMATION - SET 15 (TAC NOS. MF5347 AND MF5346)

RAI B.2.1.4-1

Background:

During the IP-71002, License Renewal Inspection, at LaSalle County Station, Units 1 and 2 (LSCS), NRC inspectors reviewed Exelon Procedure ER-AB-331, Revision 14, BWR Internals Program Management. This procedure addresses changes to the enhanced visual examination (EVT-1) requirements in boiling water reactor vessel and internals project (BWRVIP)-03, Reactor Pressure Vessel and Internals Examination Requirements. of Exelon Procedure ER-AB-331, Exelon Position on EVT-1 Implementation, states that changes relating to limitations on the allowable viewing angle have reduced the effective weld coverage to zero percent in some cases. It also states that EVT-1 inspections of required welds and components that yield an effective coverage of zero percent meet the BWRVIP inspection requirements, because the BWRVIP guidelines impose no minimum required effective inspection coverage for EVT-1 examinations. As noted in the Aging Management Program (AMP) Audit report, dated September 22, 2015, ER-AB-331is used by the BWR Vessel ID Attachment Welds and BWR Vessel Internals AMPs.

The examination requirements for American Society of Mechanical Engineers (ASME)

Section XI, for Category B-N-2 only refers to accessible welds, and does not reference a specific figure for examination surface or volume, which could be interpreted as not being a defined surface or volume and therefore, not being subject to the ASME Code requirement for essentially 100 percent coverage. However, the staffs Final License Renewal Safety Evaluation Report for BWRVIP-48 (included with BWRVIP-48-A, under BWRVIP Inspection Guidelines) states The examination volumes are limited to the attachment weld and the adjacent heat-affected regions of the vessel clad. Based on the statement in the staffs safety evaluation, the accessible welds and the adjacent heat-affected regions of the vessel clad associated with BWR Vessel ID Attachment Welds program are considered a defined surface or volume. Therefore, it is the staffs expectation that examinations performed on the accessible welds will yield essentially 100 percent coverage, which the staff considers to be 90 percent or greater coverage.

BWRVIP is one of the issue programs (IPs) included in NEI 03-08, Rev. 2, Guideline for Management of Materials Issues. As stated in NEI 03-08, All utilities shall adopt applicable IP work products in accordance with the expected level of implementation, or provide an appropriate justification for any deviations.

Issue:

Although not addressed in BWRVIP guidelines, the staffs expectation is that the examination coverage of inspections performed for AMPs based on BWRVIP guidance (i.e., Generic Aging Lessons Learned (GALL) Report AMP XI.M4 BWR Vessel ID Attachment Welds,) would be in accordance with the ASME Code. Because some BWRVIP guidelines do not address minimum required effective examination coverage, it is unclear to the staff whether limited coverage (i.e.,

less than 90 percent) is considered a deviation from the BWRVIPs expected level of implementation. In that regard, it is also unclear to the staff whether examination coverage of zero percent meets the BWRVIPs expected level of implementation. Based on this, crediting weld inspections that do not meet essentially 100 percent coverage (i.e., at least 90 percent of the accessible weld), without disposition or justification, is inconsistent with the staffs expectation for implementation of the BWRVIP-based programs during the period of extended operation.

Request:

1.

For the vessel ID attachment welds that include guidelines associated with the BWRVIP and rely on EVT-1 examinations, provide a summary of the locations where EVT-1 examinations are performed, indicate whether Alloy 182 welds are included, and the percent coverage for these examinations that can be qualified in accordance with the latest revision of BWRVIP-03.

2.

For vessel ID attachment weld locations, where examination coverage is expected to be less than 90 percent during the period of extended operation, provide the technical basis regarding the limited inspection coverage, and its adequacy to detect aging degradation prior to loss of intended function(s).

3.

For vessel ID attachment welds, provide a summary of the operating experience related to detected flaws, and the results of any flaw analyses, or other evaluations that may offer insights into flaw sizes that can be tolerated.

4.

Describe how inspection results that credit EVT-1 examinations (for vessel ID attachment welds) with minimal coverage (i.e., essentially zero percent coverage) will be documented and justified during the period of extended operation.

5.

State whether deviation reports will be submitted for inspection results for vessel attachment welds that credit examinations with limited coverage (e.g., less than 90 percent of accessible welds). If deviation reports will not be submitted, justify how the BWRVIP will provide adequate oversight of the effectiveness of the BWR Vessel ID Attachment Welds.

RAI B.2.1.7-3b

Background:

By letters dated June 25, 2015, and September 15, 2015, Exelon responded to requests for additional information (RAIs) B.2.1.7-3 and B.2.1.7-3a regarding limited examination coverage for inspections of welds associated with the BWR Stress Corrosion Cracking AMP and NRC Generic Letter (GL) 88-01. Exelons responses indicate that additional inspections to compensate for limited examination coverage are not necessary to manage cracking due to intergranular stress corrosion cracking during the period of extended operation.

As discussed in the initial RAI, GL 88-01 states, Examinations performed under the Scope of this letter should comply with the applicable Edition and Addenda of the ASME Code,Section XI, as specified in paragraph (g), Inservice Inspection (ISI) Requirements of 10 CFR 50.55a, Codes and Standards, or as otherwise approved by the NRC. In addition, the required volume for ASME Code examinations is defined as more than 90 percent of the specified volume.

Based on information from LSCSs docketed ISI reports, the examination coverage for a number of GL 88-01 welds is only 50 percent. Although the staff-approved BWRVIP-75-A, Technical Basis for Revisions to Generic Letter 88-01 Inspection Schedules, allows for modifications to the inspection extent and schedule described in GL 88-01, the modification to the inspection extent only applies to the number of welds being inspected, not the extent of examination coverage. BWRVIP-75-A does not specifically address the minimum required effective examination coverage.

Issue:

Although not explicitly addressed in BWRVIP-75-A, the staffs expectation has been that the examination coverage of inspections performed for AMPs consistent with GALL Report AMP XI.M7 BWR Stress Corrosion Cracking, would be the same as that required by the ASME Code (i.e., greater than 90 percent). BWRVIP-75-A includes a discussion about the sampling percentages from ASME Section XI Inspection requirements and notes that ASME Section XI has been the ISI mechanism for assuring a robust reactor coolant system boundary and an adequate level of plant safety. Crediting weld inspections that do not meet the required ASME Code examination coverage without specific documented justification is inconsistent with the staffs expectation for implementation of the BWR Stress Corrosion Cracking program, during the period of extended operation.

Since a minimum extent of effective examination coverage is not specified in BWRVIP-75-A, it is unclear to the staff what percentage of examination volume coverage Exelon considers as inspected for a weld examination that will be credited under the BWR Stress Corrosion Cracking program. Although Exelon has not considered additional weld inspections as being necessary to compensate for limited examination coverage, it is unclear to the staff that sufficient bases will be documented and independently reviewed to justify the limited examination coverage, where less than 90 percent of a weld has been examined. The staff considers sufficient bases, as information comparable to that which would be included in a relief request, had the inspection been an ASME Code examination.

Request:

1.

State the minimum percentage of weld volume examination coverage for a single weld to be considered inspected under the BWR Stress Corrosion Cracking program, during the period of extended operation. If the minimum examination volume coverage percentage for crediting a weld as inspected is less than 90 percent, provide the technical basis to show that adequate levels of piping integrity and reliability will be achieved, as discussed in GL 88-01.

2.

For each inspection performed under the BWR Stress Corrosion Cracking program, which will credit weld examinations with less than 90 percent coverage (during the period of extended operation),

a.

state whether documentation will be available onsite that provides the justification for the limitation, and whether the documentation will be independently reviewed to validate the justification,

b.

if documentation discussed in a) above will not be available, identify the controls that will be established to justify the limited weld examinations.