ML22013A305

Trp 143.4 St Lucie SLRA - Breakout Questions HELB

ML22013A305
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: ML22013A305 (4)

Text

St. Lucie SLRA: Breakout Questions SLRA Section 4.3.4, High Energy Line Break Analyses TRP: 143.4 Note: Breakout Questions are provided to the applicant and will be incorporated into the publicly-available audit report.

Technical Reviewer Seung Min 11/30/2021 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 4.3.4 4.3-22 SLRA Section 4.3.4 addresses the high 1. Clarify whether additional 4.3-23 energy line break (HELB) analyses. The break locations and their section indicates that the existing HELB effects will be evaluated in analysis for Class 1 reactor piping at St. the Class 1 piping HELB Lucie Unit 2 uses the guidance in the analysis if new additional Giambusso letter (December 1972), which piping break locations are is described in Branch Technical Position identified based on the CUF 3-3 (ADAMS Accesso No. ML070800027). threshold of 0.1. If not, In the guidance, the postulation of HELB provide justification for why locations is, in part, based on the such additional HELB cumulative usage factor (CUF) criterion locations do not need to be (i.e., CUF greater than 0.1) for Class 1 evaluation in the HELB piping. analysis.

SLRA Section 4.3.4 also explains that, as discussed in SLRA Section 4.3.1 and Page 1 of 4

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

Table 4.3.1-1, the original Unit 2 design 2. The applicant proposed to cycles (CLB cycles) bound the projected use the Fatigue Monitoring cycles for 80 years of operation. Based program for managing the on this evaluation, the applicant aging effect associated with determined that the fatigue analyses, the HELB TLAA. Given the corresponding cumulative usage factors proposed approach, clarify (CUFs) and Class 1 piping postulated whether the Fatigue HELB locations remain valid for the Monitoring program subsequent period of extended operation. includes a relevant action to update the HELB analysis In comparison, Branch Technical Position based on potentially new (BTP) 3-3 specifies that, if intermediate additional HELB locations Class 1 piping locations between terminal discussed in request item 1.

ends have a CUF value greater than 0.1, such locations are postulated as break locations in the HELB analysis. This CUF threshold for HELB postulation (0.1) is significantly lower than the CUF limit of 1.0 used in fatigue design analyses.

However, the applicant did not clearly address whether the 80-year operation may increase the CUF values at Class 1 piping locations above the CUF threshold of 0.1 for HELB postulation such that additional break locations needs to be evaluated in the HELB analysis.

Therefore, the staff found a need to confirm that, if new additional piping break locations are identified based on the CUF threshold of 0.1, the applicant will evaluate such new break locations in the HELB analysis.

Page 2 of 4

Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) 2 4.3.4 4.3-22 SLRA Section 4.3.4 indicates that the 1. Clarify whether the 4.3-23 existing HELB analysis for non-Class 1 sampling line is included in piping at St. Lucie Unit 2 uses the the scope of the Unit 2 guidance in the Giambusso letter HELB analysis.

(December 1972), which is described in 2. In addition, clarify whether Branch Technical Position 3-3 (ADAMS the stress range reduction Accesso No. ML070800027). In the factor of the sampling line guidance, the postulation of HELB less than 1.0 may have an locations is, in part, based on impact on HELB location the allowable stress range for expansion postulation. If so, discuss stress (Sa). Sa may need to be adjusted how the applicant by a stress range reduction factor, which addresses new potentially is, in turn, determined by the number of additional break locations thermal cycles as addressed in the and their effects on the implicit fatigue analysis in SLRA Section HELB analysis for the 4.3.2. sampling line.

In SLRA Section 4.3.4, the applicant dispositioned the HELB analysis for non-Class 1 piping in accordance with 10 CFR 54.21(c)(1)(i), indicating that the HELB analysis remains valid for the subsequent period of extended operation.

In comparison, SLRA Section 4.3.2 indicates that, except for the sampling line, the non-Class 1 piping systems involve a stress range reduction factor of 1.0 for 80 years of operation. However, the sampling line involves a 80-year projected stress range reduction factor of 0.7, which is less than 1.0. Therefore, the staff needs to clarify whether the stress range reduction factor for the sampling Page 3 of 4

Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) line (less than 1.0) may have an impact on the break location postulation in the non-Class 1 HELB analysis.

3 4

Page 4 of 4