ML15163A071

Requests for Additional Information for the Review of the LaSalle County Station, Units 1 and 2 License Renewal Application - Set 6 (TAC Nos. MF5347 and MF5346)

ML15163A071
Person / Time
Site:	LaSalle
Issue date:	07/07/2015
From:	Jeffrey Mitchell License Renewal Projects Branch 1
To:	Gallagher M Exelon Generation Co
Mitchell J, NRR/DLR, 415-3019
References
DLR-15-0303, TAC MF5346, TAC MF5347
Download: ML15163A071 (9)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 7, 2015 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 6 (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/

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

July 7, 2015 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 6 (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/

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 DISTRIBUTION: See next page ADAMS Accession Number: ML15163A071 *Concurred via e-mail OFFICE LA:DLR* PM:RPB1:DLR PM:RPB1:DLR BC:RPB1:DLR PM:RPB1:DLR NAME YEdmonds JMitchell RPlasse YDiaz-Sanabria JMitchell DATE 6/24/15 6/24/15 6/29/15 7/7/15 7/7/15 OFFICIAL RECORD COPY

Letter to Michael Gallagher from Jeffrey S. Mitchell dated July 7, 2015

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE LASALLE COUNTY STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION - SET 6 (TAC NOS. MF5347 AND MF5346)

DISTRIBUTION:

E-MAIL:

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J. Mitchell R. Plasse D. Drucker B. Wittick J. Wachutka, 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

LASALLE COUNTY STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION REQUESTS FOR ADDITIONAL INFORMATION - SET 6 (TAC NOS. MF5347 AND MF5346)

RAI B.2.1.24-1

Background:

Generic Aging Lessons Learned (GALL) Report aging management program (AMP) XI.M36, External Surfaces Monitoring of Mechanical Components, as modified by License Renewal Interim Staff Guidance (LR-ISG) LR-ISG-2012-02, Aging Management of Internal Surfaces, Fire Water Systems, Atmospheric Storage Tanks, and Corrosion Under Insulation, program element 4, detection of aging effects, recommends that [t]ightly adhering insulation is considered to be a separate population from the remainder of insulation installed on in-scope components. The entire population of in-scope piping that has tightly adhering insulation is visually inspected for damage to the moisture barrier with the same frequency as for other types of insulation inspections.

License renewal application (LRA) Section B.1.24 states in the Program Description section that the program does not require removal of tightly-adhering insulation that is impermeable to moisture unless there is evidence of damage to the moisture barrier. Instead, the program includes visual inspection of the entire accessible population of piping and components during each 10-year period of the period of extended operation.

Issue:

The staff has identified a difference between the GALL Report AMP and the applicants program. The applicants program states that it will inspect the entire accessible population of the tightly-adhering insulation components, instead of the entire population as stated in the GALL Report AMP. It is not clear to the staff what criteria were used to identify components as accessible and the basis for the acceptability of not inspecting inaccessible insulation. In addition, the staff lacks sufficient information to complete its review of this issue because it does not know the material type and environment (e.g., radiation) of the tightly adhering insulation in inaccessible locations.

Request:

Explain the criteria used in establishing categories of the accessible population and justify program adequacy if only the accessible population is inspected. In addition, state the insulation material type and environment for the inaccessible insulation.

RAI B.2.1.24-2

Background:

GALL Report AMP XI.M36, as modified by LR-ISG-2012-02, program element 4, detection of aging effects, recommends that [f]or all outdoor components (except tanks) and any indoor ENCLOSURE

components exposed to condensation (because the in-scope component is operated below the dew point), inspections are conducted of each material type (e.g., steel, stainless steel, copper alloy, aluminum) and environment (e.g., air-outdoor, moist air, air accompanied by leakage) where condensation or moisture on the surfaces of the component could occur routinely or seasonally.

LRA Section B.1.24 states in the Program Description section that [i]nspections are conducted for each external environment where condensation or moisture on the surfaces of the component could occur routinely or seasonally.

Issue:

It is not clear to the staff that each external environment will include each material type and environment as provided in the GALL Report AMP.

Request:

Explain what each external environment refers to. Justify and provide a basis if any material/environment combination will be exempted.

RAI 3.2.2.1.1-1

Background:

LRA Section B.2.1.11, Bolting Integrity, states that submerged bolting will be visually inspected for loss of material and loss of preload as enhancements to the program. Examples of submerged bolting are in the emergency core cooling system (ECCS) suction strainers, diesel fire pump suction screens, and Lake Screen House traveling screens.

The parameters monitored or inspected of AMP XI.M18, Bolting Integrity, are based on inspecting bolted connections for leakage on a frequency of at least once per refueling cycle.

LRA Section B.2.1.11 states that the inspection frequencies for submerged bolting are as follows:

• ECCS and reactor core isolation cooling (RCIC) suction strainers in the suppression pool - during each inservice inspection (ISI) interval

• Service water diver safety barriers and diesel fire pump suction screens - during maintenance activities

• Lake Screen House traveling screens framework - during each refuel cycle Issue:

It is unclear to the staff whether visual inspections for submerged bolting will consist of inspecting the bolt head only, or if a representative sample of bolts will be removed and the shank inspected. If visual inspections are only performed on the head of the bolt, loss of material in the shank region or loss of preload of the bolt might not be recognized.

The staff also noted that the inspection frequency coupled to ISI intervals for the ECCS and RCIC suction strainers is not consistent with that of the inspection frequency for AMP XI.M18.

LRA Section B.2.1.11 does not provide a defined inspection frequency for the service water diver safety barrier and diesel fire pump suction strainer bolting.

It is unclear to the staff that loss of material and loss of preload for submerged bolting will be adequately managed so that the intended function(s) will be maintained consistent with the current licensing basis during the period of extended operation, as required by Title 10 of the Code of Federal Regulations, Part 54.21(a)(3).

Request:

1. Justify the inspection parameters, such as removal of the bolt to permit inspections of the shank portion of the bolting, for the visual inspections of submerged bolting, and whether a representative sample will be removed and inspected.

2. Justify the inspection frequency in the LRA for visual inspections of submerged bolting, other than that associated with the lake screen house traveling screen framework.

RAI 3.1.2.2.1-1

Background:

LRA Table 3.1.2-3 provides the applicants summary of the aging management review for the reactor vessel internals system. LRA Table 4.3.4-1 provides the bounding cumulative usage factor (CUF) values for the reactor vessel internal components that have been analyzed for fatigue.

Issue:

LRA Table 4.3.4-1 provides the CUF values for the access hole cover and the core differential pressure and liquid control line, implying that these components are subject to cumulative fatigue damage. These two components are also included in LRA Table 3.1.2-3. However, LRA Table 3.1.2-3 does not include cumulative fatigue damage as an aging effect requiring management for either of these components.

Request:

Justify why cumulative fatigue damage is not included as an aging effect requiring management in LRA Table 3.1.2-3 for the access hole cover and the core differential pressure and liquid control line components, or revise LRA Table 3.1.2-3 to include this effect for these components.

RAI 4.2.7-1

Background:

LRA Section 4.2.7 addresses a time-limited aging analysis (TLAA) on reactor pressure vessel reflood thermal shock analysis.

Issue:

LRA Section 4.2.7 does not clearly address all parameters used in the applicants analysis. The staff needs additional information to clarify the adequacy of the applicants analysis.

Request:

As discussed above, provide the following information:

1. Orientation, shape, and maximum size of the bounding flaw which is postulated for the limiting locations of reactor vessel and nozzle.

2. Structural factor used for Service Level C (Emergency) conditions if Service Level C conditions are applicable as a bounding condition for the analysis.

3. Method used to calculate neutron fluence attenuation through reactor vessel component thickness if neutron fluence attenuation is considered.

RAI 4.3.2-1

Background:

LRA Section 4.3.2 describes two categories of license renewal systems that were designed in accordance with American Society of Mechanical Engineers (ASME)Section III, Class 2 or 3 or American National Standards Institute (ANSI) B31.1 requirements:

1. systems that are attached to ASME Section III, Class 1 piping and are affected by the same thermal and pressure transients as the Class 1 systems

2. systems that are affected by different thermal and pressure cycles related to their specific operations The first category includes the portions of the following systems: Residual Heat Removal, High Pressure Core Spray, Low Pressure Core Spray, Reactor Core Isolation Cooling, Reactor Water Cleanup, Control Rod Drive, Main Steam, Feedwater, and Condenser and Air Removal. The systems in the second category include portions of the Reactor Core Isolation Cooling, Fire Protection, and Diesel Generator and Auxiliary systems.

For both groups of non-Class 1 piping, the applicant states that the 60-year projections for the transients will not exceed 7,000 cycles, and therefore, the stress range factors originally selected for the components within these systems remain applicable for the period of extended operation. These allowable stress calculations meet the requirements for a TLAA, and the applicant dispositioned them in accordance with 10 CFR 54.21(c)(1)(i).

Issue:

LRA Tables 4.3.1-1 and 4.3.1-2 provide the 60-year cycle projections for the transients associated with the Class 2 and 3 and ANSI B31.1 piping in the Reactor Coolant System and Auxiliary Systems. The applicant stated that the systems in the first category experience the same thermal and pressure transients included in these tables. However, the applicant did not provide the applicable transient information for the second category of systems. The staff requires additional clarification on the transients and 60-year projections for these systems to verify that the cycle limits and the original allowable stress calculations will remain valid for the period of extended operation.

Request:

1. Identify the ASME Section III, Class 2 or 3 or ANSI B31.1 systems that are affected by different thermal and pressure cycles than the ones included in LRA Tables 4.3.1-1 and 4.3.1-2, including the Reactor Core Isolation Cooling, Fire Protection, and Diesel Generator and Auxiliary systems.

2. For each of the identified systems:

a) provide the transients used in the allowable stress calculations, b) provide the projected 60 year cycle count for each of these transients, and c) justify that the TLAA remains valid for the period of extended operation in accordance with 10 CFR 54.21(c)(1)(i).

RAI 4.3.3-1

Background:

LRA Section 4.3.3 states that for each Class 1 piping system or subsystem in the environmental fatigue evaluation, the applicant determined the most limiting location for each wetted material type based on the location with the highest ASME Code CUF value. The LRA further states that, in some cases, one Class 1 piping location was evaluated because the analysis represents another piping location that is bounded. The applicant defined the criteria for determining a bounded location as: a) must be affected by the same transients as the analyzed location, b) must have a lower ASME Code CUF than the analyzed location, and c) must be made from the same material or, if of a different material, the bounded material must have a lower Fen value than the bounding material.

LRA Table 4.3.3-3, Note 12 states that stainless steel location 376IJ in the N7 head spray nozzle bounds the carbon steel location 10A in the reactor core isolation cooling piping system for Unit 1.

Issue:

The staff noted that in order to have a meaningful comparison of CUF values to determine the most limiting component (or leading location) by using the highest CUF value, it is important that the CUFs were assessed similarly (e.g., amount of rigor in calculating CUF) and used the same

fatigue curves in ASME Code,Section III, Appendix I. The staff noted that through the course of plant operation it is possible that CUF values for specific components were possibly re-evaluated as part of power uprates, generic letters, bulletins, etc. to different editions of ASME Code,Section III and with varying levels of rigor when compared to the fatigue evaluations performed for the plants original design.

The staff also noted that LRA Table 4.3.3-3, Note 12 states that environmental fatigue analysis for the stainless steel location 376IJ is provided in LRA Table 4.3.3-1. The staff noted that location 376IJ is provided in LRA Table 4.3.3-2, which provides the environmental fatigue analysis results for Unit 2. The staff is unclear on either: a) which component in LRA Table 4.3.3-1 the note is referencing, or b) how a component in Unit 2 can bound a piping component in Unit 1 for consideration of environmentally-assisted fatigue.

Request:

1. Confirm that the CUFs that were compared with each other in a system to identify the location with the highest CUF value were assessed similarly (e.g., amount of rigor in calculating CUF) and used the same fatigue curves in ASME Code,Section III, Appendix I to provide a meaningful comparison. If not, provide the basis for ranking or comparing the CUFs to one another to provide an appropriate method for screening and determining a leading/limiting location.

2. Clarify which reactor pressure vessel component bounds the carbon steel location 10A from LRA Table 4.3.3-3. If the bounding component is a component in Unit 2, justify how a component or piping component can be used to bound components in different units for consideration for environmentally-assisted fatigue.

3. Identify any additional locations where a different material type was bounded by the limiting location(s) within a system and provide the system, locations, and materials that have been compared and bounded. For the carbon steel location 10A in LRA Table 4.3.3-3 and any additional locations, justify that this comparison of environmentally-adjusted CUF values between different materials within a reactor pressure vessel component or piping system for the consideration of environmentally-assisted fatigue is appropriate or valid.