ML23251A252

Attachment 1: HI-STORM 100 Amendment 18 RAI Responses

ML23251A252
Person / Time
Site:	Holtec
Issue date:	09/08/2023
From:	Holtec
To:	Office of Nuclear Material Safety and Safeguards
Shared Package
ML23251A250	List: ML23251A251 ML23251A252 ML23251A253 ML23251A254 ML23251A256
References
5014968
Download: ML23251A252 (1)

Text

Attachment 1 to Holtec Letter 5014968 HI-STORM 100 Amd 18 - Thermal and Materials RAI Clarification Questions RAI 4-1: Clarify in section 1.0.3.1 of the updated final safety analysis report (UFSAR):

a. In step 2b clarify whether, thermal model, refers to the, invariant model, and also clarify who is performing the evaluation in this step. Similarly, clarify who is: performing the evaluation in step 2c, performing the comparison in step 2d, and documenting the evaluation performed in step 2c in the sites qualification report in step 3.

b. In the first bullet of step 2b, similar to the language that is used in the first bullet of step 2, clarify that all topical report acceptance criteria (including all temperatures and pressures from tables 2.1 and 2.2 of [1.0.7]) are met when using the Holtec Report No.

HI-2200343-A Topical Report (TR) Agencywide Documents Access and Management System (ADAMS) Accession No. ML21302A147. This evaluation should then be documented in step 3, similar to the documentation performed within step 3 for the evaluation performed in step 2c.

c. As referenced in step 3, provide an example of the sites qualification report, and also describe what is meant by, as appropriate; in addition, the staff notes that configuration-controlled qualification reports will be referenced in the inspectable 72.212 report. Confirm that the TR, evaluated loading pattern is completely documented in the sites configuration-controlled qualification report.

d. That the UFSAR will be updated to reflect current bounding temperature results and the corresponding model description, if the existing UFSAR temperature results are exceeded based on the design changes or applicant-developed heat load patterns.

e. As described in section 1.0.3.1, step 5 of the UFSAR, provide whether and how the 100 percent duct blockage of the HI-STORM 100 inlet vents temperature monitoring is calculated based on the methodology in section 2.3.12 of the TR.

Regarding item a. above, additional clarification is necessary to ensure that the application is referring to the thermal invariant model with the addition of all 72.48 modifications applicable to the planned loaded canisters. Additional clarification is also necessary to ensure the staff understands who (e.g., the general licensee and Holtec as in step 1, Holtec, or the general licensee), is performing the evaluations in steps 2b and 2c, the temperature results comparison in step 2d, and the documentation in step 3.

Regarding item b. above, the thermal, 72.48 model, is based on the thermal, invariant model, which is initially evaluated in step 2 and later evaluated in step 2c. In addition, in step 2b, the TR should also be applied to the thermal, 72.48 model, with the candidate heat load pattern and evaluated using the TR to ensure that the TR acceptance criteria are met. This evaluation should then be documented in step 3 in order to demonstrate that the TR acceptance criteria are met.

Regarding item c. above, an example of the qualification report has not been provided; however, this is important to safety considering that a configuration-controlled qualification report will have the heat load pattern that has been determined to meet the acceptance criteria in the TR, which will then be used for loading operations, and is referenced in the 10 CFR 72.212 report. The sites loading pattern should be completely described in the sites configuration-controlled qualification report that is referenced and inspectable through the 10 CFR 72.212 report.

Regarding item d. above, it is not clear in section 1.0.3.1 of the application if the bounding temperature results found in the current UFSAR are exceeded that the temperature results and corresponding model description will be updated in the UFSAR. The UFSAR provides documentation of the bounding temperature results and should be updated based on sites 1

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Attachment 1 to Holtec Letter 5014968 HI-STORM 100 Amd 18 - Thermal and Materials RAI Clarification Questions configuration-controlled qualification reports if the results are exceeded based on the design changes or applicant-developed heat load patterns.

Regarding item e. above, section 1.0.3.1, step 5 of the UFSAR describes that the site ensures loading procedures have the accurate restrictions for duct blockage allowable clearance time or temperature monitoring limit and is further referred to the HI-2200343-A section 2.3.12. Part four of the response to request for supplemental information (RSI) 4-4 ADAMS Accession No. ML22122A200, addresses how the duct blockage clearance times are calculated in section 2.3.12 of the TR. However, neither section 2.3.12 of the TR, nor section 1.0.3.1 of the UFSAR, address recalculation of the temperature monitoring limits.

This information is needed to determine compliance with 10 CFR 72.236(f).

Holtec response:

a) Step 2b was updated to clarify that the thermal model described is the invariant thermal model with the 72.48 modifications applied. Responsible parties for each step have also been added.

b) The acceptance criteria for the steps referenced in item b are different because they come from two different prior NRC approvals. In steps 2a and 2b, the evaluations involve thermal models that include modifications under 72.48, which utilize the FSAR as the basis for acceptance criteria, since that is the process under the 10CFR72.48 regulation. For step 2c, the evaluation is of the heat load pattern in the topical report invariant model, and therefore, the topical report acceptance criteria apply, since those are the acceptance criteria approved for that specific invariant model.

c) A sample qualification report is included as an attachment to the letter submitting these responses d) Consistent with the existing process in Holtecs 10CFR72.48 program, if the modification under 72.48 is a generic change to the system, the FSAR is updated with new temperature results to document the bounding temperature results. However, if at a specific site a modification is made that is not generically approved, those results may not be included in the FSAR.

e) Holtec has revised Chapter 12 SR 3.1.2 to provide additional description on calculating the deltas i.e., the temperature difference between the average overpack air outlet temperature and ISFSI ambient temperature.

RAI 4-2: Clarify in the HI-STORM 100 Technical Specifications (TS), appendix A, table 3-2a, for the MPC-68M, item iii, whether the helium backfill pressure limit will be calculated for the MPC-68M with a proposed heat load greater than 42.8 kW and up to 50 kW.

It is not clear from the HI-STORM 100 TS, appendix A, table 3-2a, for the MPC-68M, item iii whether the helium backfill pressure limit is calculated for the proposed heat load limit that is greater than 42.8 kW. Therefore, based on the HI-STORM 100 TS, appendix A, table 3-2a, MPC-68M item iii, the MPC-68M cannot be loaded with a heat load limit that is greater than 42.8 kW using the QSHL loading pattern shown in appendix B, figure 2.4-1 or the QSHL patterns shown in appendix B, figures 2.4-2 through 2.4-4 because no helium backfill pressure limits are described in the HI-STORM 100 TS, appendix A, table 3-2a, for the MPC-68M, item iii.

This information is needed to determine compliance with 10 CFR 72.236(f).

Holtec response:

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Attachment 1 to Holtec Letter 5014968 HI-STORM 100 Amd 18 - Thermal and Materials RAI Clarification Questions Holtecs response clarified this RAI. No further information needed.

RAI 4-3: Provide justification for the site elevation not being evaluated if the screening criteria in section 3.4.2 of the TR are met when performing long-term storage evaluations, alternatively evaluate the site elevation for long-term storage.

Section 4.4.4.3, Effects of Elevation, of the UFSAR describes the effects of site elevation on the peak cladding temperature (PCT) (that the reduced pressure also reduces the ventilation air flow, but the site ambient temperature also decreases, resulting in a net increase in PCT). It is not clearly justified in the application why the site elevation is not being evaluated for long-term storage when using the TR because from the temperature results in section 4.4.4.3 of the UFSAR the site elevation does cause an increase in PCT. Alternatively, the site elevation for long-term storage could be evaluated.

This information is needed to determine compliance with 10 CFR 72.236(f).

Holtec response:

Holtec has revised FSAR Section 4.4.4.3 to clarify that the effects of site elevation must be evaluated and demonstrate compliance with the TR requirements.

RAI 4-4: Address the following in the TS appendix B (see RSI 4-1, ADAMS Accession No. ML22122A200).

The proposed change to TS appendix B on page 2-54, These same limits apply for heat load patterns developed in accordance with the topical report HI-2200343-A, Revision 2., should be removed because that TS is for the unventilated (UVH) overpack, which is not included in the TR SE appendix 1 list of approved design variants for HI-STORM 100 overpacks. Similarly, the maximum cell decay heat load limit in TS appendix B, table 2.4-9 should not be changed, because that TS is for the UVH overpack.

This information is needed to determine compliance with 10 CFR 72.236(f).

Holtec response:

Holtec updated this in the RAI response already provided. Table 2.4-9 has been updated to remove the previous change.

RAI 8-1: Provide a revision to the HI-STORM 100 UFSAR Section 1.0.3.1, Thermal Topical Report, to address the discrepancy in component temperatures identified in NRC RAI 8-1 for the HI-STORM 100 Amendment No. 18 application (ML23058A126).

Alternatively, provide a revision to Holtec Topical Report HI-2200343-A that addresses the component temperature limits discrepancy identified in NRC RAI 8-1, which was previously identified as NRC open Item 1 for the Thermal Topical Report as listed in Holtec letter 5014920, dated April 2, 2021 (ML21092A162), Attachment 3 (ML21092A165).

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Attachment 1 to Holtec Letter 5014968 HI-STORM 100 Amd 18 - Thermal and Materials RAI Clarification Questions RAI 8-1 requested additional information to clarify the component temperature limits for the following MPCs:

• MPCs - 24/24E/24EF

• MPCs - 32/32F

• MPCs - 68/68F/68FF/68M RAI 8-1 noted that the HI-STORM Amendment 18 application uses Holtec Topical Report HI-2200343-A (ML21302A147) for the methodology and acceptance criteria for developing heat load patterns for each canister. The staff noted that Holtec Topical Report HI-2200343-A table 2.1 is consistent with and references HI-STORM 100 UFSAR table 2.II.2.9, which is applicable to the following MPCs:

• MPC-32M

• Version 1 of the MPC-32

• Version 1 of the MPC-68 The staff also noted that Holtec Topical Report HI-2200343-A does not reference HI-STORM 100 UFSAR table 2.2.3, which provides maximum component temperatures for the following MPCs:

• MPC - 24/24E/24EF

• MPC - 32/32F

• MPC - 68/68F/68FF/68M As a result, the component temperatures listed in Holtec Topical Report HI-2200343-A table 2.1 are not consistent with component temperature limits for the MPCs covered in HI-STORM 100 UFSAR table 2.2.3.

In the NRCs review of the draft Holtec Topical Report HI-2200343-A, several open items were identified. Holtecs response to these open items was documented in Holtec letter 5014920 dated April 2, 2021 (ML21092A162), Attachment 3 (ML21092A165) non proprietary responses to the open items identified by the NRC. The NRCs open item 1 and the Holtec response are copied from Holtec letter 5014920 Attachment 3 in full below:

OPEN ITEM 1: Provide all temperature values for both the FSAR and proposed TR.

Specifically update Tables 2.1 and 4.1 with design basis temperatures and proposed TR temperatures with specific FSAR citations for where those values were obtained.

Holtec Response: Tables 2.1 and 4.1 of the TR have been revised to cite the exact source (Table number from the FSARs) of component temperature limits. Proposed temperature limits of all components except fuel cladding in Table 2.1 of the TR are consistent with those in Table 2.2.3 and 2.II.2.9 of HI-STORM 100 Amendment 15 LAR.

Similarly, the proposed temperature limits of all components except fuel cladding in Table 4.1 are consistent with those in Table 2.2.3 of HI-STORM FW FSAR. Fuel cladding temperature limits are conservatively set lower than those allowed in the FSAR and ISG-11 Rev 3. Explicit values of all component temperatures from the original source (i.e., the FSARs) are not duplicated in the TR to avoid convolution of the tables.

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Attachment 1 to Holtec Letter 5014968 HI-STORM 100 Amd 18 - Thermal and Materials RAI Clarification Questions However, the Table 2.1 of the Holtec Topical Report HI-2200343-A was not actually revised as stated in the Holtec response. As a result, the Holtec Topical Report HI-2200343-A Table 2.1 includes component temperature limits consistent with HI-STORM 100 UFSAR table 2.II.2.9.

The Holtec Topical Report HI-2200343-A does not include the temperature limits listed in HI-STORM 100 UFSAR table 2.2.3 that are applicable to the following MPCs:

• MPCs - 24/24E/24EF

• MPCs - 32/32F

• MPCs - 68/68F/68FF/68M In RAI 8.1, the staff noted that the temperature limits in listed in HI-STORM 100 UFSAR table 2.2.3 are significantly different from the component temperature limits included in HI-STORM 100 UFSAR table 2.II.2.9.

The applicants response to RAI 8-1 and the revisions to the HI-STORM 100 UFSAR Section 1.0.3.1 in response to the NRCs RAIs, do not address the discrepancy in component temperatures identified in NRC RAI 8-1.

This information is needed to determine compliance with 10 CFR 72.236(b).

Holtec response:

Holtec has voluntarily submitted an administrative change to the Topical Report, which addresses the staffs request to modify the acceptance criteria in Table 2.1. If approved, that modification will resolve this question, since the limits are consistent with Table 2.2.3 of HI-STORM 100 FSAR instead of Table 2.II.2.9. Note that the table in the topical report has consistent values for the temperature limits, however, there may be some footnotes and editorial items in the FSAR that are unrelated to the Topical Report contents that were intentionally not included in the Topical Report version of the table.

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