ML24274A301

Amendment 19 to CoC 1014 RAI Enclosure 1

ML24274A301
Person / Time
Site:	Holtec
Issue date:	10/09/2024
From:	Storage and Transportation Licensing Branch
To:	Holtec
Shared Package
ML24274A300	List: ML24274A301 ML24274A303
References
EPID L-2024-LLA-0111, CAC 001028
Download: ML24274A301 (1)

Text

Request for Additional Information

Docket No. 72-1014 Certificate of Compliance No. 1014 Amendment No. 19 to HI-STORM 100 Multipurpose Canister Storage System

The staff identified additional information needed in connection with its review of the application of Amendment No. 19 to the Certificate of Compliance (CoC) No. 1014 for HI-STORM 100 Multipurpose Canister Storage System as provided in the request for additional information (RAI) discussed below. Each question describes information needed by the staff to complete its review of the application and to determine whether the applicant has demonstrated compliance with regulatory requirements in Title 10 of the Code of Federal Regulations (10 CFR), Part 72.

Structural RAI

RAI 4-1Provide justification in the final safety analysis report (FSAR) for why the limited combinations of HI-STORM 100 dry cask storage system (DCSS) components are considered to be bounding for other combinations during structural tipover event analyses.

For the overpacks, the analysis results for the HI-STORM 100 overpack containing the Multi-Purpose Canister (MPC)-68M and MPC-68M-CBS fuel baskets are presented in this amendment to the FSAR, while the analyses for the HI-STORM 100S and 100S Version B overpacks, including Type IS which could be heavier for higher density concrete, are not presented even though they contain the same fuel baskets. This implies that the presented combinations are the limiting combinations.

Similarly for the baskets, the analysis of the CBS-type fuel baskets contained in the HI-STORM 100S Versions E and E1 overpacks are presented in the FSAR, but not all non-CBS-type basket analyses are presented. In the FSAR, provide justifications for considering these presented DCSS component combinations as bounding for other baskets or, if the justifications already exist, clearly indicate where they are located in the FSAR.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b) and (l).

RAI 4-2Provide a justification and a more detailed explanation of the new averaging method being employed in this amendment for the determination of fuel basket maximum permanent deflections resulting from the tipover event in the FSAR and associated reports.

The analytical steps performed to determine the fuel basket maximum permanent deflection are documented in notes 1 to 7 of FSAR table 3.II.4.14. For this proposed amendment, note 7 of the table allows an averaging approach to be employed for this determination, but it is not clear why an averaging approach was selected (presumably when steps 1 to 6 do not produce permanent deflection results that

Enclosure 1 2

meet the dimensionless limit of 0.005 of the fuel basket cell width). Describe why an averaging approach is justified, both from a structural and criticality standpoint.

The averaging approach is not described in the FSAR, so it is not clear exactly how an average basket permanent deflection value is determined. Provide a more detailed description of step 7 that identifies the quantities, locations and timesteps of basket cell/panel measurements required to determine the maximum average deflection value, providing a pictorial example if necessary. Additionally, FSAR sections 6.II.3.1 and 6.III.3 for criticality refer to chapter 3, however, there does not appear to be any numerical or pictorial proof provided in the discussion, figures, or tables in chapter 3 that indicate that the permanent deflections are in a few areas of the active fuel region of the baskets. It is noted by staff that effective plastic strain contours are provided in report HI-2240678, appendices C and D for the MPC-68M and MPC-68M-CBS baskets in the 100 overpack; however, there is no mention of them in the same report. Staff also notes that no temperature is indicated on these contour plots, which would be linked to material true ultimate and fracture strains.

Provide sufficient evidence in chapter 3 of the FSAR to support, or revise as necessary, the statements cited above in the criticality portion of the FSAR, as well as the following statements in FSAR sections 3.II, 3.III, and 3.IV:

The objective of the analysis is to demonstrate that the plastic deformation in the fuel basket is sufficiently limited to the value at which the criticality safety is maintained...

The fuel basket does not experience significant plastic deformation in the active fuel region to exceed the acceptable limits; plastic deformation is essentially limited locally in cells near the top of the basket beyond the active fuel region for MPC-32M basket.

The fuel basket does not experience significant plastic deformation in the active fuel region to exceed the acceptable limits; plastic deformation is essentially limited locally in cells near the top of the basket beyond the active fuel region for MPC-68M basket.

Similar to the MPC-68M basket design, the response of the MPC-68MCBS basket during the tipover event is predominantly elastic with very localized areas of plasticity.

The fuel basket does not experience significant plastic deformation in the active fuel region to exceed the acceptable limits; peak plastic deformation is essentially limited locally in cells near the impact location of the basket for MPC-32M basket.

The fuel basket does not experience significant plastic deformation in the active fuel region to exceed the acceptable limits; peak plastic deformation is essentially limited locally in cells near the impact location of the basket for MPC-68M basket.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b).

3

RAI 4-3Specify the tipover event analysis foundation model input parameters and resulting impact decelerations of the DCSS components of interest in each applicable section of the FSAR.

The independent spent fuel storage installation (ISFSI) concrete foundation system stiffness (e.g., foundation thickness, concrete compressive strength and soil subgrade modulus) included in the tipover analytical models is not consistent for each version of the HI-STORM 100 model evaluated, and there does not appear to be a reason for the apparent inconsistencies. Identify these stiffness input parameters for the tipover analysis of each DCSS component combination presented in the FSAR, identifying when the employed values may deviate from the stated licensing basis, including a justification for same. It is important to identify these values in the FSAR as the foundation system stiffness parameters employed can limit the parameters of the ISFSI pads where the DCSS can be used.

Similarly, impact deceleration values employed for the evaluation of each component of each version of the HI-STORM 100 DCSS need to be identified in the FSAR. The deceleration values are proportional to the force received by the cask and its components during tipover and are important in the tipover analysis. However, in some cases, the values stated seem to conflict with those already presented (e.g.,

the MPC-68M and MPC-68M-CBS baskets in the 100 overpack, presented in FSAR Supplement III, cite a 60-g deceleration), whereas some are not stated at all (e.g., for the unventilated high density (UVH) overpack in FSAR Supplement IV). Provide deceleration time-history plots for the (original) 100 and UVH overpack evaluations in the FSAR and associated reports.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b) and (l).

RAI 4-4Provide the method of evaluation and analyses being employed for the load-bearing MPC-68M-CBS fuel basket corner shim bolts in all applicable FSAR sections and associated reports.

The only FSAR section that addresses the structural evaluation of the load-bearing MPC-68M-CBS basket corner shim bolts is section 3.II.4.4.2(iii), for the Version E and E1 overpacks, where report HI-2188448, revision 5, Analysis of the Non-Mechanistic Tipover Event of the Loaded HI-STORM 100S Version E Storage Cask, is referenced for further documentation. [Withheld in accordance with 10 CFR 2.390, see Enclosure 2.] However, the FSAR section 3.III.4.4.3.1 describing the evaluation of the MPC-68M-CBS in the 100 overpacks, does not address the evaluation of any CBS shim bolts, whether it be the load-bearing corner shim bolts or those with oversized holes. Appendix D of the referenced report HI-2240678, revision 0, Analysis of the Non-Mechanistic Tipover Event of the Loaded HI-STORM 100,

[withheld in accordance with 10 CFR 2.390, see Enclosure 2]. Address the method of evaluation and analysis results for the load-bearing MPC-68M-CBS basket corner shim bolts in all applicable FSAR sections and reports.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b).

4

RAI 4-5Provide discussions of fuel basket and shim stresses and stress contour diagrams associated with the tipover event analyses, in the FSAR and associated reports, for those DSCC combinations included in this amendment.

Similar to what was included in the FSAR for Amendment No. 7 for the HI-STORM FW Metamic-HT baskets and shims, include stress contour diagrams of the fuel basket and shim stresses associated with the tipover event analyses, providing justification for any stresses that exceed the acceptance criterion limits. Staff notes that basket stresses exceeding the prescribed limits are discussed in the analyses detailed in all reports except that for the MPC-68M fuel basket in the UVH overpack.

This information is necessary to demonstrate compliance with 10 CFR 72.236(l).

RAI 4-6Provide justifications in the FSAR and supporting reports for fuel basket shim stresses resulting from the tipover event that exceed the material yield or ultimate strengths.

The shim stress contours resulting from the tipover event are currently only presented in the reports referenced in the FSAR. On several areas of these contours, it appears that the resulting Von Mises stresses exceed not only the material yield strength but also the ultimate strength, as listed below (the staff notes that the element erosion option of the LS-DYNA program may not be activated for the shim materials and that the set stress or strain limit may not be defined).

[Withheld in accordance with 10 CFR 2.390, see Enclosure 2.]

This information is necessary to demonstrate compliance with 10 CFR 72.236(b) and (l).

RAI 4-7Verify that the appropriate enclosure vessel geometry has been included in the structural analysis model for the tipover event evaluation of the HI-STORM 100 overpack containing the MPC-68M and MPC-68M-CBS fuel baskets.

[Withheld in accordance with 10 CFR 2.390, see Enclosure 2.] However, per FSAR section 1.II.5, this drawing is applicable to the 100S Version E and E1 overpacks, and, therefore, seemingly not applicable to an analysis of the HI-STORM 100 overpack. It appears that drawing 3923, for the MPC Enclosure Vessel, as listed in FSAR section 1.5, would be the appropriate drawing reference for the HI-STORM 100 overpack. Verify that the correct drawing reference has been made in the FSAR and that the analysis models for the evaluations of the MPC-68M and MPC-68M-CBS fuel baskets in the HI-STORM 100 overpack, as presented in the FSAR and report HI-2240678, have employed the appropriate enclosure vessel geometry.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b) and (l).

RAI 4-8Provide justifications, in the FSAR and associated reports, for the fuel basket thermal zones employed in the tipover event structural evaluations of for the HI-STORM 100 DCSS combinations containing the MPC-68M-CBS fuel basket.

5

The fuel basket thermal loads determined for each structural analysis are stated, either in the FSAR or associated calculation, to be bounding for that type of basket, and their source is stated to be report HI-2043317, revision 57, HI-STORM Thermal-Hydraulic Analysis Supporting up to 36.9 KW High Heat Load Amendment.

However, the manner in which these are translated to the modeled thermal zones for the same baskets in different overpacks is not consistent.

For the MPC-68M-CBS basket in 100S Version E and E1 overpacks, [withheld in accordance with 10 CFR 2.390, see Enclosure 2]. In comparing the modeled basket thermal zones presented in the FSAR figures (e.g., 3.II.4.32B, 3.II.4.34B, and 3.III.8) and associated report figures for the same basket, the same thermal analysis results from report HI-2043317 appear to be pictured; however, the basket thermal zones identified for the three separate analyses are disparate in arrangement and temperature range. Provide justifications for these differences.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b) and (l).

RAI 4-9Provide references in the FSAR for the definition of active fuel region for all DCSS component combinations presented in this amendment.

It appears that the active fuel region for the HI-STORM 100S Version E and E1 overpacks and components is defined in FSAR table 3.II.2.1, as referenced in section 2.II.2.4 of the FSAR. However, there does not appear to be a similar definition referenced for the 100 and UVH overpacks in FSAR sections 2.III and 2.IV, respectively. The definition of active fuel region can determine the area of highest temperatures and therefore the area of least margin to yield stress and ultimate stress.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b) and (l).

RAI 4-10Justify the differences in discretization of the ISFSI pad structural models employed in the tipover event analysis of the HI-STORM 100 overpack containing the MPC-68M and MPC-68M-CBS fuel baskets in comparison to those employed for the other DCSS combinations evaluated in this amendment.

The LS-DYNA finite element models of the ISFSI pads employed in the new analyses for the HI-STORM 100 overpack, containing the MPC-68M and MPC-68M-CBS fuel baskets, appear to have less discretization at the cask tipover impact point than those employed for the Version UVH, Version E, and Version E1 analyses. Provide the reason for this modeling change and justify the difference, specifically addressing what effect its inclusion might have on the current results for the HI-STORM 100 analyses presented in this amendment.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b).

6

RAI 4-11Submit the documents listed below, which are referenced in the submitted supporting calculations, to allow review of analysis model input parameters. If these documents have already been submitted previously, advise of the ADAMS Accession Number.

a. HI-2043317, revision 57, HI-STORM Thermal-Hydraulic Analyses Supporting up to 36.9 kW High Heat Load Amendment.

b. HI-2200285, revision 4, Dimensional Report for MPC Version CBS Baskets for the HI-STORM System.

c. HI-2002474, revision 9, Analysis of the Loaded HI-STORM 100 System Under Drop and Tipover Scenarios.

This information is necessary to demonstrate compliance with and 10 CFR 72.236(b).

RAI 4-12[Withheld in accordance with 10 CFR 2.390, see Enclosure 2.]

RAI 4-13Provide a reason for reducing the fuel assembly weight limit of the MPC-32M in the 100S Version E overpack in this amendment as well as a justification in the FSAR for the use of the original fuel assembly weight in the tipover evaluation for the MPC-32M basket in the 100S Version E overpack.

FSAR table 2.II.1.1 (and CoC appendix D, table 2.1-1, sections V.A.1.g and V.A.2.g) proposes revising the fuel assembly weight limit for the MPC-32M from 2050 lbs. to 1520 lbs. The evaluation for the MPC-32M fuel basket in the 100S Version E overpack is documented in report HI-2188448, where it is stated in section 5.1 that, rather than the revised value of 1520 lbs., the original fuel assembly weight of 2050 lbs. is employed and is considered to be a conservative input. However, FSAR section 3.A.5 states that, for the tipover event, the most conservatism is introduced into the results by using the minimum weight. Provide a justification in the FSAR that the current results presented for the MPC-32M basket in the 100S version E overpack using the original, heavier fuel assembly weight, produce the bounding tipover analysis results.

This information is necessary to demonstrate compliance with 10 CFR 72.236(b) and (l).

Materials RAI

RAI 8-1Address aging management activities related to the proposed changes in this amendment.

As stated in the renewed certificate of compliance for CoC No. 1014, Condition 14, AMENDMENTS AND REVISIONS FOR RENEWED CoC, (A)ll future amendments and revisions to this CoC shall include evaluations of the impacts to aging management activities (i.e., time-limited aging analyses and aging management programs) to ensure they remain adequate for any changes to structures, systems, and components within the scope of renewal. Provide information on aging management for this amendment.

7

This information is necessary to demonstrate compliance with 10 CFR 72.236(g).

Additional Comments/Questions

Provide a written response to the following comments/questions. Note that some of the comments/questions have been discussed during a clarification call on August 30, 2024 (ML24270A204), and a written response is requested.

1. Include 100S Version B Type IS overpack in FSAR table 1.0.4.

2. Reconcile FSAR section 2.III.0 (for 100 overpack with MPC-68M/68M-CBS baskets) where it says basket shims are NITS, with drawings 7195 for MPC-68M and 12035 for MPC-68M-CBS, which state shim (and bolts/nuts) are ITS.

3. Verify that Minimum Permitted Value is the correct title for the column of ISFSI pad data listed in FSAR table 2.II.0.1; it seems that larger pad data values would result in higher cask deceleration values. Similarly, clarify what the title Allowable means for 30 pad thickness in column of FSAR table 2.IV.0.1. Also, provide footnotes to these tables to clearly indicate any analyses within these FSAR sections that do not employ the listed values in their evaluation.

4. FSAR section 3.II.2 mentions table 3.2.5. Clarify whether it should be table 3.II.2.5.

5. Verify that the following statement of Supplement II (page 3.II-30) is still applicable, as it was deleted in Supplement IV (page 3.IV-15), or correct:

This is an improvement compared with the approach taken in the HI-STORM 100 tip-over analysis, where the loaded MPC was modeled as a cylinder and therefore the structural integrity of the MPC and fuel basket had to be analyzed separately based on the rigid body deceleration result of the cask.

6. [Withheld in accordance with 10 CFR 2.390, see Enclosure 2.]

7. FSAR page 3.III-7, as well as the relevant Holtec report, states that the MPC maximum plastic strain is 8.2%, but should be 0.82%.

8. FSAR figure 3.III.8, as well as the relevant Holtec report, for MPC-68M-CBS fuel basket in 100 overpack, the thermal zone diagram title states there is a 270°C region, but it is not labeled in the diagram. Label diagram or delete from the title.

9. Provide a figure in FSAR section 3.IV for fuel basket temperature zones for the MPC-68M fuel basket in the UVH overpack.

10. It seems that FSAR tables 3.IV.4.6 and 3.IV.4.7, which tabulate plastic strains for the MPC-32M and MPC-68M in the UVH overpack, have been deleted (per indications on proposed FSAR page 3.IV-17). Confirm and indicate table deletion in FSAR.

11. Correct FSAR figures 3.IV.4.23 to 3.IV.4.26, where new strain contour is overlapping old strain contour.

8

12. It is mentioned in the Summary of Proposed Changes document that CG changes in FSAR section 3.II.2 have been made consistent with those in FW 7. Advise what specific changes are being made as well as explaining why they are being made.

13. FSAR section 3.III.4.4.3.1 states that slotted construction of baskets means no prying, but non-CBS type Metamic-HT baskets are welded at panel seams and exterior corners. Is this statement correct? If not completely correct, clarify the applicability of this statement.

Confirm that these baskets are modeled the same way as the HI-STORM FW Amendment No. 7 baskets in this regard.

14. Cite sources in the FSAR for the fuel basket temperature zone presented in the following figures:

a. 3.II.4.11, 3.II.4.32A, 3.II.4.32B, 3.II.4.34A, and 3.II.4.34B for MPC-32M, MPC-32M-CBS and MPC-68M-CBS in 100S Version E and MPC-32M-CBS and MPC-68M-CBS in 100S Version E1.

b. 3.III.4 and 3.III.8 for MPC-68M and MPC-68M-CBS in 100.

c. 3.IV.4.12 for MPC-32M in UVH.

15. For the MPC-68M drawing 7195, revision 17, [withheld in accordance with 10 CFR 2.390, see Enclosure 2].

16. Identify maximum strain of MPC located on FSAR figure 3.II.4.15 (for MPC-32M in 100S version E overpacks). No red areas of stress contours can be seen from view shown.

Provide more information.

17. Report HI-2188448, revision 5, for 100S Versions E and E1 overpacks

[Withheld in accordance with 10 CFR 2.390, see Enclosure 2.]

18. Report HI-2210290, revision 3, for UVH overpack

[Withheld in accordance with 10 CFR 2.390, see Enclosure 2.]

19. Report HI-2240678, revision 0, for 100 overpack

[Withheld in accordance with 10 CFR 2.390, see Enclosure 2.]