ML22270A148
| ML22270A148 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 09/26/2022 |
| From: | Harris B Office of Nuclear Reactor Regulation |
| To: | Coffey R Florida Power & Light Co |
| Harris B | |
| Shared Package | |
| ML22270A147 | List: |
| References | |
| Download: ML22270A148 (2) | |
Text
ST. LUCIE NUCLEAR PLANT, UNITS 1 AND 2 SUBSEQUENT LICENSE RENEWAL APPLICATION (SLRA)
REQUESTS FOR ADDITIONAL INFORMATION (Second Round #2 - Class 1 Fatigue)
SAFETY REVIEW RAI 4.3.1-1a Regulatory Basis Pursuant to 10 CFR 54.21(c), the SLRA must include an evaluation of time-limited aging analyses (TLAAs). The applicant must demonstrate that (i) the analyses remain valid for the period of extended operation, (ii) the analyses have been projected to the end of the period of extended operation, or (iii) the effects of aging on the intended function(s) will be adequately managed for the period of extended operation.
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Background===
In the June 30, 2022, response to RAI 4.3.1-1, the applicant explained that cycle counting is not performed on the following design transients of St. Lucie Unit 1: (1) low volume control and makeup; (2) cold feed following hot standby; (3) actuation of main or auxiliary spray; (4) low pressure safety injection, 40ºF water into 300ºF cold leg; (5) opening of safety injection return line valves; and (6) loss of feedwater flow (ADAMS Accession No. ML22181A147).
The applicant explained that cycle counting is not performed on these transients based on (1) the component CUF (cumulative usage factor) value associated with the transients is not greater than 0.1 or (2) if the CUF of an associated component is greater than 0.1, the contribution of each transient to the CUF is not greater than 0.1.
Issue The applicants response to RAI 4.3.1-1 does not clearly address how the applicant considered the combined effects of these transients on CUF in the determination of cycle counting exclusion. Multiple uncounted transients could cause combined contributions to the overall CUF of a component so that the fatigue monitoring may be ineffective.
In relation to this concern, the staff noted that the following reference describes the applicants CUF evaluation for the Class 1 components and reactor coolant system piping of St. Lucie Unit 1 (
Reference:
PSL-1FSC-01-005, Revision 1, Screening of ASME Class 1 Components for License Renewal TLAA Thermal Fatigue). The reference addresses the CUF contributions of limiting transients for each component, where a limiting transient is a transient contributing to the CUF of a component more than 0.1 and is also called a fatigue-sensitive transient.
The reference also indicates that the overall CUF contribution of non-limiting transients is in the range from 0.21 to 0.78 for the following Unit 1 components: (1) steam generator primary head at divider seat bar; (2) pressurizer bottom head support skirt; (3) surge line resistance temperature detector (RDT) nozzle; and (4) surge line sample nozzle. The staff is seeking
clarification whether the non-limiting transients for these components include multiple uncounted transients.
Request Clarify whether two or more uncounted transients are included in the non-limiting transients for the following Unit 1 components: (1) steam generator primary head at divider seat bar; (2) pressurizer bottom head support skirt; (3) surge line RTD nozzle; and (4) surge line sample nozzle. If so, discuss why cycle counting is not needed for the transients even though multiple uncounted transients could cause combined contributions to the overall CUF of a component so that the fatigue monitoring may be ineffective.