ML20225A191
| ML20225A191 | |
| Person / Time | |
|---|---|
| Site: | 07201032 |
| Issue date: | 08/12/2020 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML20225A188 | List: |
| References | |
| 5018079 | |
| Download: ML20225A191 (3) | |
Text
Attachment 1 to Holtec Letter 5018079 Amendment Request 1032-7
SUMMARY
OF PROPOSED CHANGES All changes to the CoC and FSAR are marked in the subsequent attachments. Changes that have occurred as part of prior applications are not marked as changes.
Proposed Change #1 Addition of a new variant of the HI-STORM FW Overpack, called HI-STORM FW UV, where the UV stands for unventilated. The overpack is a simplified version of the HI-STORM FW System wherein the overpacks inlet and outlet air passages have been removed, resulting in a complete cessation of ventilation in the space between the cask cavity and the stored multi-purpose canister (MPC) during the systems operation.
Reason for Proposed Change #1 The HI-STORM FW UV is needed to serve as a low-dose MPC storage system wherein the external environment around the canister is sought to be controlled, such as to protect from stress corrosion cracking.
Justification for Proposed Change #1 The new overpack has been evaluated and is fully described in the provided Supplement I to the FSAR.
This supplement provides the necessary information and analyses to support the HI-STORM FW Version UV. The supplement identifies the areas which are impacted by the new overpack design, and each chapter also lists the sections that are unaffected by the new design. The new overpack is structurally, thermally, and shielding qualified to meet all the requirements of 10CFR72. There is no change to the criticality or confinement evaluation, since the MPCs are unchanged from previous HI-STORM FW amendments. Related to this change is the increased temperature limit for the MPC baseplate from 400 oF to 425 oF, which has been analyzed for all MPCs in Chapter 3 of the FSAR.
Proposed Change #2 Modify vent and drain penetrations to include the option of second port cover plate.
Reason for Proposed Change #2 The addition of a second cover plate for these penetrations removes the need to do field helium leak testing of these cover plates.
Justification for Proposed Change #2 See attached Licensing Memorandum: Proposed design change for MPC Lid Port Covers to improve ALARA and ruggedness of the MPC for increased reliability of confinement integrity The HI-STORM FW CoC, MPC drawings, and FSAR Chapter 9 and 10 have been updated to include this change.
Proposed Change #3 Allow automated equipment to perform leak test of the MPC materials and welds in the fabrication shop.
Justification for Proposed Change #3 The acceptance criteria for the leakage test will remains unchanged when implementing the automated process. By automating the leakage testing process, there will be more reliable and repeatable testing and to Holtec Letter 5018079 Amendment Request 1032-7
SUMMARY
OF PROPOSED CHANGES eliminate possibility for human error. The current testing relies on Level III qualifications, which requires a large amount of training, of which not many personnel are qualified. The HI-STORM FW FSAR Chapter 8 and 10 have been updated to include this change Proposed Change #4 Change the hydrostatic pressure test of the MPC acceptance criteria to be examination for leakage only.
Remove post hydrostatic test PT examination.
Reason for Proposed Change #4 The post hydrostatic pressure test PT examination is not an ASME Code requirement and causes incurred dose without corresponding safety benefit.
Justification for Proposed Change #4 The HI-STORM FW CoC, and FSAR Chapter 9 and 10 have been updated to include this change.
Proposed Change #5 Inclusion of the ability to run a CFD analysis to evaluate site-specific fire scenarios.
Reason for Proposed Change #5 The CFD analysis allows for an alternate and accurate modeling of site-specific fire, using the models that are already approved for normal conditions.
Justification for Proposed Change #5 FSAR Section 4.6 has been updated to include this change. The acceptance criteria and the thermal model adopted for analysis remain unchanged when implementing the CFD method.
Proposed Change #6 Use updated methodology for tornado missile stability calculations for freestanding HI-STORMs and HI-TRACs. Clarify the weights to be used for varying heights of HI-TRACs.
Reason for Proposed Change #6 The change updates the methodology for tornado missile stability analysis to consider changing restoring arm as a cask lifts up and rotates. Also to provide weight information for HI-TRACs that may be loaded with less than the maximum fuel assemblies.
Justification for Proposed Change #6 Structural analysis, as outlined in the updated Chapter 3, shows that all safety factors remain acceptable with the new analysis method and provides additional information on HI-TRAC loaded weights for clarity.
Editorial Changes to Holtec Letter 5018079 Amendment Request 1032-7
SUMMARY
OF PROPOSED CHANGES Update the description of the HI-STORM FW system in the CoC to clearly indicate that only the portions of the components that come into contact with the pool water need to made of stainless steel or aluminum.
Update the statements in FSAR Section 3.2 related to CG eccentricities in the evaluation of lifting devices. The previous FSAR commitment does not stem from any requirement in NUREG-0612 or ANSI N14.6. This FSAR requirement is unnecessary since ANSI N14.6 mandates increased design factors of 6 and 10 with respect to material yield and ultimate strength, which adequately compensates for small CG variations.