ML22013A302

Trp 143.1 St Lucie SLRA - Breakout Questions Class 1 Fatigue

ML22013A302
Person / Time
Site:	Saint Lucie
Issue date:	12/21/2021
From:	Office of Nuclear Reactor Regulation
To:
Rodriguez-Luccioni H
References
EPID L-2021-SLR-0002, L-2021-SLR-0002
Download: ML22013A302 (4)

Text

St. Lucie SLRA: Breakout Questions SLRA Section 4.3.1, Metal Fatigue of Class 1 Components TRP: 143.1 Note: Breakout Questions are provided to the applicant and will be incorporated into the publicly-available audit report.

Technical Reviewer Seung Min 12/9/2021 Technical Branch Chief Matt Mitchell 12/21/2021 Breakout Session Date/Time To be filled in by PM Applicant Staff NRC staff To be filled out by PM during breakout Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) 1 4.3.1 4.3-2 SLRA Tables 4.3.1-1 and 4.3.1-2 1. Explain why the second describe the 80-year projected cycles for cycle projection method the design transients, which were uses only the recent 10 included in the original PSL LRA for PSL years of the cycle counting Units 1 and 2 respectively. for 80-year cycle projections. As part of the The SLRA indicates that the 80-year response, clarify whether projections of the transient cycles use the second projection the cumulative cycle counts for each method results in the more transient monitored on each unit up to conservative 80-year cycle December 31, 2019. The SLRA also projections (i.e., more explains that the cycle counts are projected cycles) than the projected to 80 years of operation (1) first projection method (i.e.,

based on a direct extrapolation of the the direct extrapolation of cycle counts through the subsequent the cycle count).

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Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) period of extended operation (SPEO) or (2) based on cycle accumulation over the recent 10 years of cycle counting (up to December 31, 2019) and then by pro-rating the counts for the remaining years to the end of the SPEO.

However, the SLRA does not clearly explain why the second cycle projection method for some transients uses only the cycle counts from the recent 10 years of the cycle counting.

2 4.3.1 4.3-10 SLRA Tables 4.3.1-1 and 4.3.1-2 1. For the transients excluded 4.3-11 describe the design transients, which from fatigue monitoring were included in the original PSL LRA for based on cycle margins, PSL Units 1 and 2 respectively. These describe the cycle margins tables indicate that some transients will (e.g., margins beyond the not be monitored in the Fatigue actually accumulated Monitoring program (e.g., plant loading, cycles with respect to 80-5 percent/minute and 10 percent step year projected cycles and load increase transients). design cycle) to confirm that cycle margins are In addition, Tables 1 and 2 of large enough to exclude Westinghouse LTR-SDA-II-20-32-NP the transients from fatigue indicate that the transients, which will not monitoring.

be monitored in the Fatigue Monitoring program, are consistent with the transients that are not monitored in the 2. For the transients excluded current licensing basis (i.e., the initial from fatigue monitoring license renewal term up to 60-year based on fatigue usage operation). The tables explain that these contributions, clarify design transients were excluded from the whether the 80-year monitoring of the Fatigue Monitoring evaluation considers all the Page 2 of 4

Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) program because the transients resulted contributions of the in a fatigue usage less than 0.1 or large excluded transients on margins were present with respect to fatigue usage to confirm actual cycle counts versus allowable that the total contributions cycle limits. of the transients for an applicable location do not The staff found a need to confirm that the exceed the contribution basis of excluding these transients from limit (0.1), as opposed to a fatigue monitoring remains valid for 80 single contribution of a years of operation. specific transient. If not, justify why the combined effects of the transients on fatigue usage are not considered in the determination for fatigue monitoring exclusion.

3 4.3.1 4.3-2 SLRA Seciton 4.3.1 states that the 1. Clarify whether the Fatigue 4.3-12 transients, which are included in the Monitoring program will current PSL Fatigue Monitoring program monitor the additional but not included in the original PSL LRA transients that are for PSL Units 1 and 2, are presented in described in SLRA Tables Tables 4.3.1-3 and 4.3.1-4, respectively. 4.3.1-5 and 4.3.1-6. If not, The SLRA also indicates that SLRA justify why the additional Tables 4.3.1-5 and 4.3.1-6 describe the transients in the table do 80-year projections for additional not need to be monitored transients (e.g., loss of letdown flow in the Fatigue Monitoring transient cycles) that support subsequent program for SPEO.

period of extended operation (SPEO) fatigue evaluations.

2. With respect to the pressurizer spray nozzle The SLRA does not clearly discuss cumulative usage factor whether the Fatigue Monitoring program addressed in SLRA Table Page 3 of 4

Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) will monitor the additional transients for 4.3.1-4, describe the 80 years of operation, which are relevant transients and described in SLRA Tables 4.3.1-5 and their cycle limits, 4.3.1-6. accumulated cycles and 80-year projected cycles, In addition, SLRA Table 4.3.1-4 consistent with the other addresses the pressurizer spray nozzle transient listings.

cumulative usage factor in the column for the additional Unit 2 transients that are included in the fatigue monitoring.

However, this item does not clearly describe relevant transients and their cycle limits, accumulated cycles and 80-year projected cycles. The staff found a need to clarify the transients and associated cycles for this item.

4 4.3.1 4.3-4 SLRA Section 4.3.1 addresses the metal 1. Discuss the following fatigue TLAA for Class 1 components and items: (1) the design piping. transients used in the However, the section does not clearly cumulative usage factor discuss the following items: (1) the design (CUF) calculations for transients used in the cumulative usage pressurizer surge lines; (2) factor (CUF) calculations for pressurizer the associated design surge lines; (2) the associated design cycles, actual cycles and cycles, actual cycles and projected 80- projected 80-year cycles; year cycles; and (3) how the applicant and (3) how the applicant ensures that actual cycles do not exceed ensures that actual cycles the design cycles. do not exceed the design cycles.

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