ML24065A305

Attachment 3 - Conversation Record HI-STORM Flood-Wind Storage System Amendment 7 Meeting Summary (Non-proprietary)

ML24065A305
Person / Time
Site:	07201032
Issue date:	01/26/2024
From:	Office of Nuclear Material Safety and Safeguards
To:	Holtec
References
CAC 001028, EPID L-2021-LLA-0053
Download: ML24065A305 (2)

Text

Attachment 2 Conversation Record Summary Clarification Call with Holtec on HI-STORM Flood/Wind (FW) Amendment 7 January 26, 2024

1. Strain rate effects: Holtec stated that it will not consider strain rate effects for Metamic--HT based on staffs comments during the January 10, 2024 meeting. Holtec will keep the strain rate effects as an inherent conservatism for their analysis.

2. Treatment of localized stresses: Holtec presented several reasons for local stresses and had made adjustments in its model (of the multi-purpose canister [MPC]-37-CBS) to reduce these occurrences.

a.

Due to the presence of higher local stresses at element boundaries where temperature-dependent properties had the greatest delta, Holtec had changed the temperature-dependent properties to be more granularized than before. Holtec changed the number of temperature-dependent properties used for the basket from 4 to 13. Holtec also reduced the temperatures to be closer to the actuals, rather than providing a large margin. For example, where the thermal analytical maximum was 358°C, Holtec used 380°C for structural model.

b.

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PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390

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3. Enhanced LS-DYNA model for 37-CBS basket: Holtec considered MPC-37-CBS as a bounding basket and made the following changes to the model for MPC-37-CBS basket analysis:

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PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390

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With these changes, Holtec has improved the results as follows:

i.

Deflection results have changed from SF of 1.25 to 1.9. (Holtec does not plan to replace the existing deflection results in the safety analysis report [SAR] because they include conservative margins.)

ii.

All total stress results are below 100% true ultimate stress. Local stress concentrations shown appear to be at basket notch/slot junctions.

4. Next step: Holtec plans to update the calculation packages and revise SAR chapters 2 and 3 to explain its current approach of using MPC-37-CBS for bounding analysis.

[PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390 Holtec plans to provide written responses to clarification questions to RAI responses, including SAR changes, by February 15, 2024.

Staff questioned throughout the meeting whether Holtec plans to perform these changes for a different basket other than MPC-37-CBS, e.g., MPC-37, where local total stresses were two times of the allowable. Holtec agreed that it would consider it as a sensitivity study although it might delay the anticipated response schedule.