ML26019A018
| ML26019A018 | |
| Person / Time | |
|---|---|
| Site: | HI-STORM 100 |
| Issue date: | 01/16/2026 |
| From: | Holtec |
| To: | Office of Nuclear Reactor Regulation, Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML26019A016 | List: |
| References | |
| 5021083 | |
| Download: ML26019A018 (0) | |
Text
1 HI-STORM UMAX Amendment 6 Summary of Proposed Changes (SOPC)
Change #1 Introduce a new version of the HI-STORM UMAX CEC (Version F)
Reason for Proposed Change #1 Certification of the new design of the UMAX CEC (Version F) is being requested generically for all fuel types. This new version offers improved shielding capabilities. The new cask will introduce a new lid, an outboard inlet and outlet vent pipes, and a stability wedge. All MPCs currently allowed in the UMAX will also be implemented into UMAX Version F, as well as the new canisters added in Proposed Change #4 Justification for Proposed Change #1 Version F of HI-STORM UMAX is included into the FSAR in Supplement I. The new version is either analyzed by each discipline for the same design conditions as the previously certified system or it is documented why the existing analyses remain bounding.
Change #2 Introduce a new HI-TRAC VW Monolithic Shield Cylinder (MSC) Design, which utilizes Holtite instead of water or lead. This HI-TRAC design also does not use a mating device during transfer.
Reason for Proposed Change #2 The HI-TRAC VW MSC is utilized to optimize transfer operations at the site. The design provides additional shielding for personnel. The elimination of the need for a mating device simplifies the download operation Justification for Proposed Change #2 The HI-TRAC VW MSC is included into the FSAR throughout the main body. The new version is either analyzed by each discipline for the same design conditions as the previously certified system or it is documented why the existing analyses remain bounding.
Change #3 Add new fuel classification (17x17G) to the HI-STORM UMAX FSAR and CoC Reason for Proposed Change #3 Some utilities need the ability to load fuel into dry storage that does not meet any of the current allowable content types.
to Holtec Letter 5021083
2 Justification for Proposed Change #3 The new fuel type is within the existing size and weight limits and therefore has no impact on structural and there are no different operations required from any fuel type. The fuel has the same heat load restrictions as all other fuel types and therefore has no impact on thermal. The fuel has been evaluated by shielding and criticality and shown to be acceptable as documented in the proposed updates to the HI-STORM UMAX FSAR.
Change #4 Incorporate MPC-37CBS and MPC-89CBS across all variants of the HI-STORM UMAX Reason for Proposed Change #4 The MPC-37CBS and MPC-89CBS are variants of the existing MPCs certified for use in the HI-STORM UMAX system. The basket variants are better in fabrication space as they use bolted shims which eliminates weld distortion. This change will align the UMAX with the canisters allowed in the HI-STORM FW.
Justification for Proposed Change #4 The new MPC variants are either analyzed by each discipline for the same design conditions as the previously certified system or it is documented why the existing analyses remain bounding.
Change #5 Incorporation of a methodology to develop site specific loading patterns in Chapter 4 of the HI-STORM UMAX FSAR and inclusion of higher maximum per canister and per cell limits for those patterns.
Reason for Proposed Change #5 The need to store fuel with higher per-assembly heat load fuels is projected to grow further. It has been determined that individually developed patterns would give more flexibility to loading plans. This loading pattern methodology is similar to the methodology developed in the NRC approved Thermal Topical Report HI-2200343.
Justification for Proposed Change #5 The methodology being used is similar to a methodology previously approved by the NRC. The heat load patterns are required to maintain compliance with the same acceptance criteria previously approved for the storage system. Therefore, the system maintains the same level of safety as the previously certified systems.
Change #6 Incorporation of the Topical Report on the Radiological Fuel Qualification Methodology for Dry Storage Systems, Holtec Report HI-2210161-A. to Holtec Letter 5021083
3 Reason for Proposed Change #6 Incorporating this topical report will increase flexibility in developing loading patterns and loading plans. It will also simplify the analysis, review and approval process for this license amendment, and reduce the need for future license amendments.
Justification for Proposed Change #6 The process outlined in the FSAR is the implementation of the NRC reviewed topical report, which has been approved. Modifying the contents according to this methodology ensures that the shielding performance of the system continues to meet regulatory requirements.
Change #7 Remove the previously established 20% heat load penalty applied during the initial licensing of the HI-STORM UMAX System Reason for Change #7 Removing penalties will allow design basis heat loads to be loaded into the HI-STORM UMAX.
Justification for Change #7 Chater 4 of the proposed HI-STORM UMAX FSAR provides benchmarking data to show the thermal performance of the overpack continues to meet acceptance criteria at design basis heat loads. Based on this updated benchmarking, the penalty is no longer appropriate.
to Holtec Letter 5021083