ML22024A049

Breakout Questions - Trp 143.9 - Cycle Projections

ML22024A049
Person / Time
Site:	Oconee
Issue date:	01/19/2022
From:	Angela Wu NRC/NRR/DNRL/NLRP
To:
Wu A, 301-415-2995
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Oconee SLRA: Breakout Questions SLRA Section 4.3.1, Transient Cycle Projections for 80 Years TRP: 143.9 Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed) 1 4.3.1 4-51 SLRA Section 4.3.1 states that the 1. Clarify whether a condition Fatigue Monitoring program will track report will be issued as part cycles for significant fatigue transients of the fatigue monitoring listed in Table 4.3.1-1 and will ensure activities to ensure that the corrective action is taken prior to CUF and environmental potentially exceeding fatigue design CUF limit (1.0) as well as limits. SLRA Section 4.3.1 also states each design cycle is not that a condition report will be initiated exceeded. In addition, based upon an administrative limit of 80 clarify whether the 80 percent of the fatigue cycles or if the percent of the CUF and minimum time for any transient event total environmental CUF limit occurrence projection to reach the (i.e., 0.8) will be used as the allowable is less than three years. threshold for the issuance of a condition report.

As discussed above, SLRA Section 4.3.1 addresses the issuance of a condition report regarding fatigue monitoring to ensure the number of cycles for each design transient does not exceed the design cycle limit. However, SLRA Section 4.3.1 does not clearly address the issuance a condition report to ensure the cumulative usage factor (CUF) and environmental CUF values do not exceed the design limit (1.0).

Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed) 2 4.3.1 4-52 SLRA Section 4.3.1 indicates that the 1. Explain why SLRA Table fatigue analyses are based upon 4.3.1-1 does not explicitly numbers and amplitudes of thermal and address Transients 1A1 pressure transients in UFSAR Table 5-2, through 1A5 and Transients Transient Cycles for RCS [reactor 1B1 and 1B2 for the coolant system] Components Except pressurizer surge lines and Pressurizer Surge Line and UFSAR their design cycles and Table 5-23, Operating Design Transient cycle projections. If the lack Cycles for Pressurizer Surge Line. of these transients cannot be justified, revise SLRA Specifically, SLRA Table 4.3.1-1 Table 4.3.1-1, consistent describes the 80-year projected transient with UFSAR Table 5-23 and cycles in comparison with the design provide the 80-year transient cycles that are described in projected cycles for these UFSAR Tables 5-2 and 5-23. transients.

In its review of the transients, the staff noted that Transients 1A1, 1A2, 1A3, 1A4 2. Clarify why the following and 1A5 (heatup transients) and design transients and their Transients 1B1 and 1B2 (cooldown design cycles in UFSAR transients) for the pressurizer surge line, Table 5-2 are not explicitly are listed in UFSAR Table 5-23 but these identified in SLRA Table transients are not clearly identified in 4.3.1-1: Transients 3, 4, 5, SLRA Table 4.3.1-1. 6, 12, 18, 19 and 20. If the The staff also noted that the following lack of these transients transients in UFSAR Table 5-2 are not cannot be justified, revise listed in SLRA Table 4.3.1-1: (1) SLRA Table 4.3.1-1, Transient 3, power loading 8 to 100 consistent with UFSAR percent power; (2) Transient 4, power Table 5-2 and provide the unloading 100 to 8 percent power; (3) 80-year projected cycles for Transient 5, 10 percent step load these transients.

increase; (4) Transient 6, 10 percent step load decrease; (5) Transient 12, hydrotests; (6) Transient 18, loss of

Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed) feedwater heater; (7) Transient 19, feed and bleed operations; and (8) Transient 20, miscellaneous transients.

The staff finds a need to resolve this potential inconsistency between SLRA Table 4.3.1-1 and the UFSAR transient tables.

3 4.3.1, 4-54 SLRA Table 4.3.1-1, Note 1 and the 1. Provide the reduced set of Table related discussion in SLRA Section 4.3.4 allowable transient cycles 4.3.1-1 indicate that, the pressurizer surge line, discussed in SLRA Table main steam penetrations and main 4.3.1-1, Note 1.

feedwater penetrations have a reduced set of transient cycles, compared the design transient cycles listed in SLRA 2. Clarify whether the Fatigue Table 4.3.1-1. Monitoring program will perform monitoring to However, SLRA Sections 4.3.1 and 4.3.4 ensure that the actual do not clearly provide the following transients do not exceed information: (1) the reduced set of the the reduced set of transient transient cycles and (2) whether the cycles.

Fatigue Monitoring program will monitor the reduced set of the transients.

Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed) 4 4.3.1 4-52 SLRA Section 4.3.5 addresses the 1. Clarify whether the 4.3.5 4-71 analytical evaluation of flaws for the 80- analytical evaluations of all year operation. The section indicates that the flaws discussed in the flaws identified for initial license SLRA Section 4.3.5 use renewal have been re-evaluated or the the design transients and component containing the flaw has been cycles identified in SLRA replaced. SLRA Section 4.3.5 also Section 4.3.1 without explains that these reanalyzed flaws are assuming a reduced set of now acceptable for their full controlling transient cycles. If not, design basis transient cycles as identify the reduced set of discussed in Section 4.3.1. transient cycles.

In comparison, UFSAR Table 5-2, Note 1 indicates that certain components have 2. Clarify whether the flaw tolerance evaluations (as addressed transients and cycles used in UFSAR Sections 5.2.2 and 5.2.3.12.4) in SLRA Section 4.3.6 that assume a reduced number of heatup (weld overlay fatigue and cooldown cycles for the evaluations. analysis) are bounded by the design transients and Therefore, the staff finds a need to further cycles identified in SLRA confirm that, except for the pressurizer Table 4.3.1-1.

surge line flaw tolerance evaluations separately addressed in SLRA Section 3. Clarify whether the Fatigue 4.3.4, the analytical evaluations of all the Monitoring program will flaws discussed in SLRA Section 4.3.5 ensure that the actual use the design transients and cycles transient cycles do not identified in SLRA Section 4.3.1 without exceed the transient cycles using a reduced set of transient cycles. that are assumed in the The staff needs a similar confirmation for flaw evaluations and weld the weld overlay fatigue analysis overlay fatigue analysis.

discussed in SLRA Section 4.3.6.

Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed) 5 4.3.1 4-51 Note 2 of UFSAR Table 5-2 indicates that, 1. Clarify whether the in order to analytically demonstrate a reduced cycles of the usage factor of less than 1.0, certain transients specified in welds associated with the emergency high Notes 2 and 7 of UFSAR pressure injection (HPI) nozzles have Table 5-2 are applied to been qualified for fewer than the design the design cycles number of cycles of two transients as described in SLRA Table follows. Specifically, the sum of the cycles 4.3.1-1.

of the manual actuation of HPI system after reactor trip transient (Transient 8) 2. Justify why SLRA Table and the cycles of rapid depressurizations 4.3.1-1 does not include transient (Transient 9) cannot exceed 29 Transients 3, 4 and 12 in cycles. UFSAR Table 5-2 that involve the reduced cycles Similarly, Note 7 of UFSAR Table 5-2 for the reactor vessel explains that the reactor vessel closure closure head assemblies.

head assemblies are limited to 5000 If it cannot be justified, cycles of power loading and unloading revise SLRA Table 4.3.1-1 transient (Transients 3 and 4) and 15 to include these transients, cycles of hydrotests transient (Transient consistent with UFSAR 12). Table 5-2.

In contrast, SLRA Table 4.3.1-1 does not include the design transients that have the reduced set of cycles that are specified in Notes 2 and 7 of UFSAR Table 5-2. The staff needs to resolve this potential inconsistency.