ML17283A040

Enclosure 2 - Nrc'S Presentation Slides-Seabrook Station, License Amendment Request, Stage 3 Methodology

ML17283A040
Person / Time
Site:	Seabrook
Issue date:	10/10/2017
From:	Justin Poole Plant Licensing Branch 1
To:
Poole J, NRR/DORL/LPLI, 415-2048
Shared Package
ML17283A039	List: ML17278A748 ML17283A040 ML17283A041
References
CAC MF8260, EPID L-2016-LLA-0007
Download: ML17283A040 (9)

Text

Seabrook Station License Amendment Request Stage 3 Methodology Justin Poole, Project Manager, DORL, NRR Bryce Lehman, Structural Engineer, DE, NRR George Thomas, Senior Structural Engineer, DE, NRR

Agenda

• Issues with Current Stage 3 Methodology

• Staff Expectations for Methodology

• Path Forward

• Schedule Discussion 2

Stage 3 as Described in LAR

• Description in LAR of advanced techniques proposed to be used is high-level with no implementation details provided for staff to evaluate as a generic method of evaluation

• Includes methods whose implementation appear open to interpretation, with no specific applicability limitations, justification or acceptance criteria, and may be outside the design code (ACI 318-71)

• LAR notes that analysis will demonstrate compliance with ACI 318-71 3

Staff Concerns with Stage 3

• It is unclear how the methodology as described in the LAR could be consistently applied and similar results obtained

- Significant decisions in the Containment Enclosure Building (CEB) calculation appear to be based on engineering judgement

- Stage 3 uses iterative processes with no clear limitations 4

Staff Concerns with Stage 3

• Review of Containment Enclosure Building (CEB) calculation identified several general issues:

- ACI 318-71 requirements for moment redistribution do not appear to be met or justified; approach used does not appear to be supported by accepted concrete codes

- Acceptance criteria are not provided for the structural adequacy of sections to develop a plastic hinge

- A limit on moment redistribution iterations is not provided

- No guidance is provided on determining the threshold factor or under what circumstances it can be modified

- No evaluation of serviceability limit state included under normal service load conditions that include ASR 5

Staff Expectations for Methodology

• The LAR or UFSAR mark-up should include sufficient detail to allow qualified engineer to follow the process through any Stage 3 calc

- How ACI 318-71 requirements will be met and/or justification for alternatives and requirements that are not met

- Guidance/criteria on when proposed analysis techniques and methods can be used

- Limits on the use of iterative processes

- Identified rebar strain limits under normal service conditions including ASR load 6

Path Forward:

Potential LAR Supplement

• Potential LAR supplement options:

- Update LAR to include detailed, consistently applicable methodology; staff will review a sample of completed calculations

- Approval of partial methodology (Stage 1 & 2); all final Stage 3 evaluations for NRC review and approval

- Other options?

• Approach is up to NextEra 7

Impacts on Schedule

• Staff intends to review a sampling of completed Stage 1, 2 and 3 analyses

- Sampling dependent on analysis complexity and issues identified

• Schedule dependent on analyses availability

- Analyses should be approved and incorporated by NextEra prior to NRC review 8

Questions?

9