ML22013A304

Trp 143.3 St Lucie SLRA - Breakout Questions EAF

ML22013A304
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: ML22013A304 (7)

Text

St. Lucie SLRA: Breakout Questions SLRA Section 4.3.3, Environmentally-Assisted Fatigue TRP: 143.3 Note: Breakout Questions are provided to the applicant and will be incorporated into the publicly-available audit report.

Technical Reviewer Seung Min 12/7/2021 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 4.3.3 4.3-21 SLRA Section 4.3.3 addresses the 1. Provide justification for not environmentally-assisted fatigue (EAF) identifying the charging analysis for the reactor coolant system. system nozzle in the As part of the EAF analysis, Tables 3-1 sentinel location list of LTR-and 3-2 of Westinghouse LTR-SDA-II SDA-II-20-31-NP, Revision 31-NP, Revision 2 report provide the 2 even though the leading EAF locations (also called component is identified as a sentinel locations) for the equipment leading EAF location for components and piping components, Combustion Engineering respectively. designed plants in NUREG-6260. If the charging In comparison, NUREG/CR-6260 system nozzle is bounded identifies the charging system nozzle by another location in terms location as one of the EAF leading of environmental cumulative locations for Combustion-Engineering- usage factor (CUFen),

designed plants. However, Tables 3-1 Page 1 of 7

Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) and 3-2 of Westinghouse LTR-SDA-II identify the bounding 31-NP, Revision 2 does not clearly location and provide the discuss the EAF analysis results for the environmental fatigue charging system nozzle. correction factor (Fen) and CUFen values of the bounding location and charging system nozzle location to demonstrate the bounding nature of the other leading location.

2 4.3.3 4.3-21 SLRA Section 4.3.3 addresses the 1. Clarify how the applicants environmentally-assisted fatigue (EAF) determination of the analysis for the reactor coolant system. leading EAF locations In addition, Westinghouse LTR-SDA-II- evaluates the piping 20-31-NP, Revision 2 describes the systems or zones that are applicants approach for determining the exposed to different EAF leading locations. thermal and pressure transients. As part of the The SLRA does not clearly address how response, clarify whether the determination of the leading EAF the leading EAF locations locations evaluates the piping systems or are determined based on zones that are exposed to different the environmental thermal and pressure transients. cumulative usage factors in each piping system or zone that is exposed to essentially the same thermal and pressure transients.

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Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) 3 4.3.3 4.3-21 The following BWXT report discusses the 1. Provide justification for environmentally-assisted fatigue (EAF) excluding the plant analysis for St. Lucie Unit 1 replacement loading/unloading, 10 steam generators (

Reference:

BWXT percent step load Report MSLEF-SR-01-NP, Revision 0, St. increase/decrease, and Lucie Unit 1 Replacement Steam normal plant vibration Generator Environmentally Assisted transients from fatigue Fatigue Report). Table 2 of the BWXT monitoring even though report lists the design transients analyzed these transients and in the EAF analysis. associated cycles are used in the EAF analysis for Unit SLRA Section 4.3.1 and Table 4.3.1-2 2 steam generators. As indicate that some of the transients, part of the response, which are used for the CUFen calculations explain how the applicant in the BWXT report, will not be monitored can ensure that the actual in the Fatigue Monitoring Program for cycles of these transients subsequent period of extended operation. do not exceed the cycles The transients, which the applicant analyzed in the CUFen proposed not to monitor, are the calculations of the BWXT following: (1) plant loading/unloading report.

transient; (2) 10 percent step load increase/decrease transient; and (3) normal plant vibration transient.

The analyzed cycles of the plant loading/unloading, 10 percent step load increase/decrease, and normal plant vibration transients in the EAF analysis of the BWXT report are 2077, 2000 and 1000000 cycles, respectively. The staff found a need to confirm the adequacy of excluding these transients from fatigue monitoring.

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Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) 4 4.3.3 4.3-21 The following BWXT report discusses the 1. Explain why transient pair environmentally-assisted fatigue (EAF) number 4 involves a analysis for the St. Lucie Unit 1 significantly greater Fen replacement steam generators value compared to the

(

Reference:

BWXT Report MSLEF-SR- other transient pairs. As 01-NP, Revision 0, St. Lucie Unit 1 part of the response, Replacement Steam Generator compare the temperature, Environmentally Assisted Fatigue strain rate, coolants Report). Table 5 of the BWXT report dissolve oxygen and steel summarizes the EAF analysis results for sulfur content values used steam generator tubesheet solid rim near in the Fen calculations the tubesheet dome. The tubesheet solid between transient pair 4 rim is fabricated of low alloy steel. and the other transient pairs.

Table 5 of the BWXT report also indicates that the environmental fatigue correction factor (Fen) for transient pair number 4 is 2. Clarify the following items:

greater than the Fen values for the other (1) which cycles are used transient pairs by a factor of 6.7 in the Fen calculations approximately. The staff found a need to between the design cycles clarify why transient pair number 4 and 80-year allowable involves a significantly greater Fen value cycles listed in Table 5 of compared to the other transient pairs. the BWXT report; and (2) whether the allowable In addition, Table 5 of the BWXT report cycles for the transient lists both the design transient cycles and pairs in Table 5 of the the 80-year allowable cycles. The staff BWXT report are based on needs to clarify the following items: (1) the acceptable 80-year which cycles are used in the projected cycles of the environmental cumulative usage factor transients described in (Fen) calculations between the design Table 2 of the BWXT cycles and the allowable cycles for the report.

transient pairs; and (2) whether the allowable cycles are based on the Page 4 of 7

Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) acceptable 80-year projected cycles of the transients described in Table 2 of the BWXT report.

5 4.3.3 4.3-21 The Framatome 86-9329644-001 report 1. Provide justification for summarizes the environmentally-assisted excluding the plant fatigue (EAF) analysis for St. Lucie Unit 2 loading/unloading, 10 replacement steam generators, Unit 1 and percent step load 2 replacement reactor vessel closure increase/decrease, and heads, Unit 2 pressurizer repairs, Unit 2 cold feedwater following weld overlays and Unit 2 auxiliary spray hot standby transients line reducer (

Reference:

Framatome from fatigue monitoring Document Number 86-9329644-001, St. even though these Lucie SLR CUFen Evaluations Summary, transients and associated July 15, 2021). reduced cycles are used in Table 5-2 of the Framatome report the EAF analysis of the specifies the reduced cycles of the Framatome report.

transients that are used in the environmental cumulative usage factor 2. Clarify whether the (CUFen) calculations, as reduced from the primary coolant pump design cycles. Some of these transients, starting/stopping transient which involve limited (reduced) cycles of St. Lucie Unit 2 will be compared to design cycles, will not be monitored in the Fatigue monitored in the Fatigue Monitoring Monitoring program. If not, program, as indicated in SLRA Section provide justification for 4.3.1. excluding the transient The transients, which are used for the from fatigue monitoring.

CUFen calculations in the Framatome report and will not be monitored in the Fatigue Monitoring program, are the 3. Clarify whether the spray following: (1) plant loading/unloading nozzle, main spray transient; (2) 10 percent step load initiation, auxiliary spray increase/decrease transient; and (3) at power 1, auxiliary Page 5 of 7

Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) cold feedwater following hot standby spray at power 2, and transient. Given that these transients and main spray term in their reduced cycles are used for the cooldown transients will CUFen calculations in the Framatome be monitored in the report, the staff found a need to confirm Fatigue Monitoring the adequacy of excluding these program to ensure that the transients form fatigue monitoring. actual transient cycles do The staff also noted that the primary not exceed the cycles coolant pump starting/stopping transient projected and analyzed in (also designated as the DP transient) is the EAF analysis of the used in the EAF analysis for the Unit 2 Framatome report. If not, steam generator tube-to-tubesheet weld. provide justification for However, SLRA Section 4.3.1 and excluding these transients Framatome report do not clearly address from fatigue monitoring.

whether the pump transient for St. Lucie Unit 2 will be monitored in the Fatigue Monitoring program.

In addition, SLRA Section 4.3.1 and Framatome report Tables 5-2 and 5-3 (addressing pressurizer spray nozzle transients) do not clearly address whether the following transients related to Unit 2 pressurizers, which involve reduced cycles in the CUFen calculations, will be monitored in the Fatigue Monitoring program: (1) spray nozzle transient (also called the spray nozzle transient 17A/B/C); (2) main spray initiation transient; (3) auxiliary spray at power 1 and auxiliary spray at power 2 transients; and (4) main spray term in cooldown transient.

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Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) 6 Page 7 of 7