ML24031A661
| ML24031A661 | |
| Person / Time | |
|---|---|
| Site: | HI-STORM 100 |
| Issue date: | 01/31/2024 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML24031A659 | List: |
| References | |
| 5021074 | |
| Download: ML24031A661 (1) | |
Text
Attachment 1 Holtec Letter 5021074 RSI Responses on HI-STORM UMAX Revisions to Amendments 0, 1, and 2 RSI.
Provide supplemental information that clarifies the scope of the application.
The May 5, 2023, application for Revision to HI-STORM UMAX CoC No. 1040, Amendments 0, 1, and 2 consists of a cover letter, a summary of proposed changes, CoC page changes for the proposed Revision 1 to Amendment Nos. 0, 1, and 2, and corresponding final safety analysis report (FSAR) page changes for proposed FSAR Revisions 2.1, 3.1, and 4.1 that are associated with each CoC amendment.
The May 5, 2023, cover letter states that, Other HI-STORM UMAX users have already chosen to upgrade their casks to Amendment 4, which already includes these changes. The summary of proposed changes in the application notes that the reason for the requested revisions is outlined in referenced Holtec letters, which discuss Amendment No. 4. The September 28, 2023, email from Holtec (see ML23292A347) notes that the intent of the application was to match what was previously approved in Amendment No. 4. Additionally, the proposed CoC page changes in the application match those approved in Amendment No. 4, which reflect measured dose rate limits of 66 millirem (mrem)/ hour (hr) for the Standard Lid and 22 mrem/hr for the Version B Lid (see January 4, 2021, issuance of CoC No. 1040, Amendment No. 4,, at ML20349A209). Therefore, it appears that the intended scope of the application for Revisions to UMAX Amendment Nos. 0, 1, and 2 is intended to match the previous change that was made in Amendment No. 4.
However, the proposed FSAR page changes in the application do not reflect those in Amendment No. 4. Holtec submitted the final FSAR page changes for Amendment No. 4 in the March 30, 2020, Holtec submittal 5021060, Attachment 4 (see ML20104C018), which incl udes FSAR table 5.4.7 design basis dose rate limits of 66 mrem/hr for the Standard Lid and 22 mrem/hr for the Version B Lid. Additionally, the April 13, 2020, Holtec response to a clarification RAI on Amendment No. 4 notes, The dose limits in 5.3.4.a of the CoC Appendix A are revised to be 66 mrem/hr for the standard lid and 22 mrem/hr for the Version B lid. These are the same calculated dose rate values reported in the SAR table 5.4.7 and supporting calculation packages (see ML20111A239). Instead, the application includes design basis dose rate limits in table 5.4.7 of the FSAR page changes, of 180 mrem/hr for the Standard Lid and 60 mrem/hr for the Version B Lid. In response to an NRC staff query on whether the FSAR page changes in the application were correct and intentional as they did not match the CoC page changes in the application, Holtec responded (see ML23292A347) that the CoC and FSAR page changes in the application were intentional to match what was previously approved in Amendment No. 4.
Therefore, it is not clear what is the intended scope of the application. Clarify if the intended scope of the application is to: (a) reflect the changes approved in Amendment No. 4 regarding dose rate limits of 66 mrem/hr for the Standard Lid and 22 mrem/hr for the Version B Lid; or (b) revise dose rate limits to 180 mrem/hr for the Standard Lid and 60 mrem/hr for the Version B Lid.
- If (a), submit revised FSAR page changes that reflect Amendment No. 4.
- If (b), provide a description of the changes that result in higher FSAR dose rate limits and their measurement locations and the supporting calculation files.
The NRC staff needs this information to begin a detailed review of the application for Revisions to UMAX Amendment Nos. 0, 1, and 2 to determine if it meets the regulatory requirements of Title 10 of the Code of Federal Regulations (10 CFR) Part 72.
Attachment 1 Holtec Letter 5021074 RSI Responses on HI-STORM UMAX Revisions to Amendments 0, 1, and 2 Holtec Response:
Holtec apologizes for the confusion. The intent in these revisions is to match the approved Amendment 4 information. Therefore attached to this letter are updated FSAR change pages that reflect Amendment No. 4.
Observation.
Justify the proposed TS condition that excepts general licensees from taking additional dose rate measurements to comply with the proposed Revision 1 measurement requirements, if the general licensees took the required dose rate measurements on vertical ventilated modules (VVMs) loaded to Revision 0. Alternatively, remove this proposed TS condition language.
The summary of proposed changes in the application notes:
Note that this change does not modify the requirement under Sections 5.3.2 and 5.3.3
[in CoC Appendix A TS] for the licensee to calculate a site specific surface dose rate limit based on site condition, ISFSI configuration, number of casks, and contents to confirm compliance with 10 CFR 72.104. As stated in Section 5.3.5 [in CoC Appendix A TS], the lower of these limits shall be used to compare with measured values. The revised measurement location ensures that the appropriate location of dose rates is measured. However, it is important to note that as long as the locations for measured and site-specific calculated values are the same, a successful comparison provides reasonable assurance that 10 CFR 72.104 is met.
It is important to recall that the proposed revisions to the TS were found to be necessary not only because of questions about the measurement location. They were also necessary because the dose rate limit value for the VVM lid was non-conservative and not based on the FSAR analyses for demonstrating sufficient shielding to meet 10 CFR 72.104. The FSAR analyses indicated that the TS-identified measurement location on the VVM lid had a significantly smaller dose rate in the FSAR analyses for meeting § 72.104 than the TS limit. Plus, in application of the Revision 0 measurement location description to a new lid design (Version B lid), the identified location for that lid was clearly not an appropriate location for a dose rate that would give any indications regarding the purposes of the measurement limit and location. Further, the NRC staff noted that the general licensees use the TS dose rates to inform their emergency action levels for emergency response following an event. Thus, the appropriateness of the proposed TS condition language is unclear and not adequately justified.
With the proposed TS condition language, the applicant is attempting to justify for the general licensees that have loaded UMAX systems under Revision 0 of the CoC that actions taken to comply with Revision 0 are adequate to comply with Revision 1 (minus this proposed condition language). This is something that general licensees are required to do as described in 10 CFR 72.212. For the applicant to be able to adequately justify the proposed condition language, it would need to provide information similar to what the general licensee would include in its § 72.212 evaluation report. This information would include evaluations of how the previously performed measurements compare versus the new limit values and locations, including in demonstrating the objectives of the limit are met (e.g., confirm proper system loading and that § 72.104 limits will be met). For example, the applicant could provide information that demonstrates that dose rate measurements performed on VVMs loaded to Revision 0 are bounded by the proposed dose rate limits in the application, in terms of dose rate measurements and locations of the measurements. Additionally, the applicant could provide information to demonstrate that the general licensee that previously took dose rate measurements on VVMs loaded to Revision 0 meets the dose limits of § 72.104 and the performed measurements support demonstration of that compliance.
Attachment 1 Holtec Letter 5021074 RSI Responses on HI-STORM UMAX Revisions to Amendments 0, 1, and 2 Alternatively, the applicant should remove the proposed TS condition from the application. In this case, the general licensee who previously loaded to Revision 0 would need to implement Revision 1 after it is issued. The general licensee would need to perform an evaluation per § 72.212 to determine what is needed to implement the revised CoC, and to establish that the casks conform to the terms, conditions, and specifications of the revised CoC and that the requirements of § 72.104 are met.
This information is required to demonstrate compliance with 10 CFR 72.236(d) and § 72.104.
Holtec Response
Holtec included this provision in the original application, because there appears to be little safety benefit of taking additional measurements (and incurring additional personnel dose rates) for casks that have been loaded for a number of years and have no indications that the 10CFR72.104 limits were challenged. However, Holtec understands the staffs observation and the need for either additional information or removal of the proposed condition. Since this was part of the voluntary acceptance of a revision given by the user, Holtec will work with the impacted user to develop acceptable changes to the condition or to provide the staff with additional information to justify the condition.
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