ML23338A308
| ML23338A308 | |
| Person / Time | |
|---|---|
| Site: | Holtec |
| Issue date: | 12/04/2023 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML23338A304 | List: |
| References | |
| 5014974 | |
| Download: ML23338A308 (1) | |
Text
Attachment 3 to Holtec Letter 5014974 1.0.3 Implementation of Topical Reports 1.0.3.1 Thermal Topical Report The NRC has reviewed and approved Topical Report HI-2200343-A [1.0.7]. This report outlines a methodology for developing heat load patterns for each canister. Throughout this FSAR, the areas where the topical report can be applied are identified. However, since the topical report itself is specifically focused on the thermal methodology, this section provides an outline of the approach for implementing that methodology. For additional clarity, a flowchart of the process is included in Figure 1.0.1.
Change Control The NRCs SER [1.0.8] explicitly lays out restrictions on the scope of the review for the topical report. Most notably, limitation 4.2 describes the model reviewed for the scope of the topical report as invariant. However, since this FSAR is subject to the provisions of 10CFR72.48, use of that topical report needs to address the change control process. Note that in all cases, the HI-STORM 100 system being considered must be one of the models listed in Appendix 1 of [1.0.8]
The following explains the steps in the flow chart in Figure 1.0.1 for implementation of the topical report
- Step 1: Site decides the existing CoC heat load patterns do not meet their needs, and develops a new pattern that would meet fuel loading needs
- Step 2: General Licensee and Holtec determine if the HI-STORM 100 system and contents being loaded matches the invariant model in the topical report [1.0.7]
o If yes, then proceed through the qualification process outlined in the topical report, ensure all topical report acceptance criteria (including all temperatures and pressures from Tables 2.1 and 2.2 of [1.0.7]) are met, and rejoin at Step 3 o If no, follow steps 2a through 2d
- Step 2a: Ensure that the variations from the topical report [1.0.7] invariant model (identified in Step 2) are acceptable without prior NRC approval o This process is identical to Holtecs existing 72.48 program and should be documented accordingly, which develops a 72.48 model for that variation o If the 72.48 process indicates that prior NRC approval is required, that application must be made and approved by the NRC prior to use of the HI-STORM 100 system. The topical report methodology [1.0.7] cannot be used until NRC approval is obtained.
- Step 2b: Once the variations have been determined to be acceptable without prior NRC approval under 72.48, the sites candidate heat load pattern should be evaluated by Holtec or the General Licensee in the 72.48 model, which is the invariant thermal model with all 72.48 modifications applicable to the planned loaded canisters applied o The results of this calculation must show that all components have a lower temperature than the limits prescribed in the thermal topical report and pressures lower than the thermal topical report limits o The peak cladding temperature (PCT) from this analysis is then compared to the results from Step 2c HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22E REPORT HI-2002444 1-6 Page 1 of 3
Attachment 3 to Holtec Letter 5014974
- Step 2c: The candidate heat load pattern is then fully qualified for use by evaluation by Holtec or the General Licensee in the Topical Report [1.0.7] invariant model o This evaluation must show ALL Topical Report [1.0.7] acceptance criteria are met, including all temperatures and pressures from Tables 2.1 and 2.2 of [1.0.7]
o This evaluation must show a higher PCT than Step 2b o If either of these conditions is not met, the candidate heat load pattern must be revised and Steps 2b and 2c are repeated. The original candidate heat load pattern is not eligible for loading.
- Step 2d: The temperature results from both Steps 2b and 2c are compared by Holtec or the General Licensee to the structural evaluations in the FSAR o If FSAR structural evaluations use temperatures that bound the calculated temperatures, no further structural evaluations are needed o IF FSAR structural evaluations use temperatures that do NOT bound the calculated temperatures, an additional 72.48 must be performed to demonstrate the new temperatures are acceptable without NRC approval If the structural evaluation changes are not acceptable under 72.48 than either the candidate heat load pattern must be changed or application made to the NRC and NRC approval obtained prior to use of the topical report
[1.0.7] methodology
- Step 3: Once all the items and acceptance criteria in Step 2a through 2d are satisfied -
Holtec or the General Licensee document the evaluation performed in Step 2b, and Step 2c (candidate heat load pattern in invariant model) in sites qualification report and referenced in the general licensees 72.212 report. Sites can use Section 5.0 of HI-2200343-A as an example format for this qualification report.
- Step 4: Site chooses fuel to meet the qualified heat load pattern, confirming that the fuel also meets other CoC requirements, such as (but not limited to) fuel types and FQTs (see below shielding discussion)
- Step 5: Site ensures loading procedures have the accurate restrictions for:
o Helium Backfill - HI-2200343-A Section 2.3.6 o Time to boil - HI-2200343-A Section 2.3.8 o Duct Blockage allowable clearance time or temperature monitoring limit - HI-2200343-A Section 2.3.12 Shielding The fuel qualification limits for burnups, enrichments and cooling times (BECTs) are independent of the fuel decay heat limits, and any assembly has to meet both the applicable BECT limits, and any decay heat limit developed through the application of the Topical Report.
No changes are made for now to these BECT limits, and no additional dose calculations are needed for the existing limits. Hence there are no new shielding analyses needed as a consequence of introducing the Topical Report. For further discussions and explanations see the following paragraphs.
Independence of BECTs and decay heat limits Earlier revisions of this FSAR included an explicit link between BECTs and decay heat limits, and this also impacted the way the dose analyses were performed. The link was specified in the HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22E REPORT HI-2002444 1-7 Page 2 of 3
Attachment 3 to Holtec Letter 5014974 Figure 1.0.1: Thermal Topical Report Implementation Step 1 - Site develops candidate heat load pattern Step 2c - Use the topical report invariant thermal Step 2b - Use the model model to evaluate the developed with all Step 2a - Ensure that sites candidate heat applicable 72.48 the variations load pattern -
Step 2 - does the HI- No modifications to identified in Step 2 acceptance criteria are STORM 100 and system evaluate the sites are acceptable under as outlined in the topical and contents being used candidate heat load the existing CoC/FSAR report, and PCT must be at site match the TR pattern - acceptance under 72.48, if not higher than Step 2b. If invariant model criteria are process stops not, process stops temperatures and pressures lower than topical report criteria. If Yes not, process stops Step 2d - Compare the Step 3 - Evaluate the candidate heat load bounding temperatures of pattern under the topical report each component from 2b methodology and document in and 2c to those used in the qualification report, with all limitations FSAR structural analysis, (backfill, etc.) and update structural analysis if needed and permitted under 72.48. If Step 4 - Site chooses fuel to meet the Step 5 - Site ensures loading not permitted under qualified heat load pattern confirming procedures have the accurate 72.48, process stops that the fuel also meets other CoC restrictions based on the topical requirements, such as BECT report methodology combinations HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22D REPORT HI-2002444 1-38 Page 3 of 3