ML25273A345
| ML25273A345 | |
| Person / Time | |
|---|---|
| Site: | 07109374 |
| Issue date: | 09/30/2025 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML25273A342 | List: |
| References | |
| EPID L-2024-LL-0096, 2370019-NRC | |
| Download: ML25273A345 (1) | |
Text
Holtec Response to Request for Additional Information Non-Proprietary Request for Additional Information Docket No. 71-9374 Model No. HI-STAR 80 Package Certificate of Compliance No. 9374 Revision No. 3 Chapter 2: Structural Analysis RAI 2-1.
Provide (a) the definition of permanent deflection1, and (b) the method for the measurement of the fuel basket permanent deflection in safety analysis report (SAR) HI-2146261, Revision 6, as has been done for previous Title 10 of the Code of Federal Regulations (10 CFR) Part 72 licensing amendments adopting this method of evaluation for Metamic-HT fuel baskets.
SAR section 2.1.2.2(ii)b defines the numerical limit for the maximum permanent deflection of both the F-12P/F-12P-CBS and F-32B/F-32B-CBS fuel baskets fabricated from Metamic-HT material, but does not define permanent deflection, nor does it outline the steps to determine this measurement. In section I.2.2. of calculation report HI-2167023, Revision 7, Finite Element Analysis of HI-STAR 80 Transport Package for Postulated Drop and Puncture Accidents, the determination of the Metamic-HT fuel basket maximum permanent deflection is described as requiring an averaging of deflection values across the fuel basket panel width to compare to the acceptance criteria. While the 10 CFR Part 72 HI-STORM Flood/Wind (FW) (license amendment request [LAR] 72-1032-07) documented the updated method of evaluation for Metamic-HT fuel basket deflection acceptance criteria, the averaging of deflections as part of the method of evaluation was introduced in HI-STORM 100 Amendment 19 (LAR 72-1014-19), and was only employed as necessary, and with certain restrictions that added conservatism to the results. Therefore, it is suggested that this statement in the calculation should be revised to include those restrictions. The step-wise method to acquire the maximum permanent deflection of the fuel basket is presented in section I.6.0 of the calculation report and aligns with that presented in LAR 72-1014-19; it is recommended that this method be presented in the SAR, preferably table 2.7.6, similar to what was presented in the notes of Table 3.II.4.14 of the HI-STORM 100 SAR, HI-2002444, Revision 25. Finally, as it appears that the maximum permanent deflection value reported in report table I.8.3 for the F12-P-CBS basket did not require deflection averaging (step 7), it is recommended that the double-asterisked note be revised to the same wording provided for SAR HI-2002444 table 3.II.4.14: Calculated values are maximum permanent deflections at mid-span of basket panel (per steps 1 thru 6 above); element averaging (per step 7 above) is not performed. Maximum calculated deflection also includes perimeter fuel basket panels. Revise the calculation and update the SAR as required.
This information is required to satisfy the requirements of 10 CFR 71.41(a).
1 Staff notes that Holtec provided a definition of permanent deflection in Step 6 of the measurement determination procedure presented in section I.6.0 of calculation report HI-2167023. to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 1 of 25
Holtec Response SAR section 2.1.2.2(ii)(b) has been revised to enhance the definition of permanent deflection by mirroring the text in sections 2.II.2.6(ii) and 2.III.0.1(i) of HI-STORM 100 Amendment 19 (LAR 72-1014-19). In addition, the method for the measurement of the fuel basket permanent deflection has been added to the SAR in Table 2.7.7 (which accords with Table 3.II.4.14 of the HI-STORM 100 FSAR, HI-2002444, Rev. 25).
Finally, sections I.2.2 and I.6.0 of calculation report HI-2167023, as well as Table I.6.3 (formerly Table I.8.3), have also been revised per the staffs request.
RAI 2-2.
Provide quantitative results in SAR tables 2.6.7 and 2.7.6, which present results for Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) fuel basket permanent deflections and identify the sources of the numerical data.
SAR tables 2.6.7, for NCT, and 2.7.6, for HAC, report that the deflection portion of the fuel basket permanent deflection acceptance criteria, as described in SAR section 2.1.2.2(ii)b, have been met during certain conditions with an entry of YES. However, not all the sources for confirmation of this compliance could be found in calculation report HI-2167023, Revision 7. In calculation report section 8.0, it is stated that figures 8.10.9 and 8.4.7 indicate that the fuel basket does not experience any gross plastic strain after the NCT and HAC drop analyses, but no quantitative deflection results are documented. Figure 8.10.9 contours appear to be the basis for the results reported in SAR table 2.6.7, while an unquantified average of basket permanent deformation averaged over the entire width and length of the active fuel region appears to be the basis for the results reported in SAR table 2.7.6. Table I.8.3 of the calculation contains the only numerical permanent deflection fuel basket results for the 30-foot drop analyses, which are HAC events, and only for the F12-P-CBS basket. Revise the calculation and update the SAR as required.
This information is required to satisfy the requirements of 10 CFR 71.41(a).
Holtec Response The quantitative deflection results for the F-32B and F12P-CBS baskets are now presented in Table 2.7.7 of the SAR for the HAC drop analyses. Also, calculation report HI-2167023 has been revised to include the deflection results for the F-32B basket in Table 8.1.A (similar to Table I.6.3 for the F12P-CBS basket).
With regard to the NCT drop analyses, the fuel basket deflections are significantly less than those computed for the HAC drop analyses due to the substantial difference in drop height (1-ft vs. 30-ft). This is reflected in Figures 8.10.9 and 8.4.7 in calculation report HI-2167023, which show that the peak strain in the fuel basket due to 1-ft drop is 6 times less than the peak strain due to 30-ft drop. More importantly, as stated in Section 8.0 of HI-2167023, the active fuel region of the fuel basket does not experience any plastic deformation during the 1-ft side drop.
Since the fuel basket deflection criteria are the same for NCT and HAC, and the fuel basket permanent deflection results for HAC clearly bound those for NCT, there is no need to precisely quantify the fuel basket deflection results for NCT using the step-wise method presented in SAR Table 2.7.7. Instead, a footnote has been added to SAR Table 2.6.7 to to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 2 of 25
indicate that the fuel basket permanent deflections reported in SAR Table 2.7.7 for HAC also bound the NCT drop event (i.e., Load Combination N2).
RAI 2-3.
Justify the statements in the SAR that the important-to-safety (ITS) bolts connecting the continuous basket shims (CBS) to the fuel baskets experience no loads during lateral impact events the basket experiences. Additionally, explain how the bolts and the CBS and basket surfaces are modeled in the LS-DYNA finite elements program to simulate this expected behavior.
SAR section 2.3.1 states that the bolts connecting the CBS shims to the fuel baskets experience no load during a lateral impact event, however, it also states that they are tightened to secure the CBS to the baskets. Explain how CBS basket bolts are modeled in LS-DYNA, as well as the interface between the basket shims and panels: is it possible to verify that any axial movement of the shims relative to the basket does not exceed the clearance between the bolt and the edge of the bolt hole?
This information is required to satisfy the requirements of 10 CFR 71.41(a).
Holtec Response The CBS attachment bolts for the F12P-CBS and F32B-CBS fuel baskets are of the same general design and behave in a very similar manner as the CBS attachment bolts for the MPC-37-CBS and MPC-89-CBS in the HI-STORM FW FSAR (docket 72-1032). The reason that these bolts are not part of the primary load path during a lateral impact event is because [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]. The purpose of the CBS bolts is to maintain the CBS in proper position during handling of the fuel basket and during installation (or withdrawal) of the basket in (or from) the HI-STAR 80 containment cavity.
[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
With respect to the full spectrum of normal and accident condition loadings, as defined in subsection 2.1.2.1 of the HI-STAR 80 SAR, the only loading conditions that cause some level of stress in the CBS attachment bolts are normal handling loads and a bottom/top end drop under hypothetical accident conditions (HAC). When the fuel basket is being lifted vertically, the CBS attachment bolts associated with the corner CBS must be capable of supporting the dead weight of the fuel basket assembly (without fuel). [ to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 3 of 25
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
] Therefore, the CBS attachment bolts have ample strength to resist the dead weight of the CBS during normal handling.
During a 9-meter end drop, the peak axial deceleration is less than 90g per SAR Table 2.7.3A. [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
] Therefore, the CBS attachment bolts have sufficient shear capacity to resist the amplified weight of the CBS during an end drop.
[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
].
RAI 2-4.
Verify and justify the reason that there is no acceptance criterion for the fuel basket shims.
The staff could not identify an acceptance criterion for the ITS fuel basket shims in SAR section 2.1.2.2, especially for the critical loading of a HAC drop event. Likewise, the structural condition of the shims is not checked as part of the HAC drop event evaluation documented in calculation report HI-2167023, Revision 7. Staff notes that the fuel basket shims for the HI-STORM FW (docket 72-1032) and HI-STORM 100 (72-1014) storage systems are checked after the non-mechanistic tipover event to verify that their stresses are mainly below yield strength with only limited permanent deformation.
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This information is required to satisfy the requirements of 10 CFR 71.41(a).
Holtec Response The HAC drop event causes only localized plasticity in CBS with no material failure and no gross deformation. Local yielding of the CBS shims is permissible provided that the fuel basket satisfies the maximum deflection limit set forth in SAR section 2.1.2.2. The Von Mises stresses in the CBS (within the active fuel region) are plotted in Figures I.8.3.7, I.8.3.8, and I.8.3.9 of calculation report HI-2167023 (rev. 8). [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]. In summary, the CBS maintain their physical integrity during a lateral impact event as the stresses in the basket shims are mainly below the yield strength with only limited permanent deformation.
RAI 2-5.
Justify the addition of notes, as indicated in the list below, on the Metamic-HT material fuel basket drawings that allow material substitutions in specific areas of the basket. Verify that these materials are the same thickness as the original, and that these changes do not affect any of the technical analyses performed in support of this amendment, e.g.,
structural, thermal, criticality, material compatibility. Also, explain how the specific length of fuel assemblies that the basket will be permitted to transport in the future is known at the time of basket fabrication, such that the active fuel region location is able to be defined at that time.
Note 18 of Sheet 3, Drawing 9796, Revision 8, F12P Basket Note 18 of Sheet 3, Drawing 9797, Revision 8, F32B Basket Flag Note 13, Drawing 15305, Revision 2, F32B-CBS Basket Flag Note 13, Drawing 15624, Revision 1, F12P-CBS Basket The new drawing notes allow the original Metamic-HT panels of the fuel basket, to be replaced by specific alternate materials. The note states that no coating is required (or prohibited) for emissivity purposes. It does not appear to staff that any neutron-absorbing material is required to be added in the area of these new materials.
Confirm that these alternate material panels are the same thickness as the original Metamic-HT basket panels. SAR tables 7.D.2 and 7.D.3 indicate the maximum active fuel lengths for the various pressurized-water reactor (PWR) and boiling-water reactor fuel assemblies, respectively, that may be loaded into the HI-STAR 80 transport cask. Specify whether it is known prior to basket fabrication which fuel assembly type is expected to be transported in each basket being fabricated, such that the active fuel region length and location is able to be to be defined, allowing the proposed material substitutions. Advise how the information for this fuel-assembly-specific basket is tracked such that no other fuel assembly types are loaded in this specific basket in the future. Confirm that these material substitutions, per the note requirements have no effect on the results of any the technical analyses documented in the application that verify the packages ability to comply with 10 CFR Part 71 requirements.
This information is required to satisfy the requirements of 10 CFR 71.33(a)(5)(iii) and 71.41(a). to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 5 of 25
Holtec Response Materials other than Metamic HT used for basket panels must be the same thickness as other panels in the stack. Considering the restricted list of materials specified on the drawings, and the restricted placement and dimensions of these non-Metamic HT materials, the impact on basket performance and analysis is negligible from structural, thermal, criticality, shielding, and material compatibility perspectives.
The lower and upper elevations of the active fuel region for all fuel described in SAR Tables 7.D.2 and 7.D.3, are known. Restrictions on optional material elevations are based on the position of the active region, conservatively combined with no use of fuel spacers, conservatively assuming the basket and fuel may slide axially during cask transport, into the least favorable overlap of active region and Metamic HT.
For PWR assemblies, the start of the active region must be a minimum of [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] above the bottom of the fuel assembly. No more than [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] elevation of the bottom row of PWR basket interlocking basket panels may employ these optional materials.
For all PWR fuel assemblies, the active region must end no less than [ PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] below the top of the fuel assembly.
No more than [ PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]
of elevation at the top of the interlocking PWR basket panels may employ the optional materials.
For all BWR fuel assemblies, the start of the active region must be a minimum of [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] above the bottom of the fuel assembly. No more than [ PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] elevation of the bottom row of BWR basket interlocking basket panels may employ these optional materials.
For all BWR fuel assemblies, the active region must end no less than [ PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] below the top of the fuel assembly.
No more than [ PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]
of elevation at the top of the interlocking BWR basket panels may employ the optional materials.
Limitations on active fuel region position are added to SAR Tables 7.D.2 and 7.D.3. Notes on F12P drawing 9796 and F12P-CBS drawing 15624 are updated to include these clarifications. Notes on F32B drawing 9797 and F32B-CBS drawing 15305 are updated to include these clarifications.
RAI 2-6.
For the CBS baskets, provide further information regarding the ITS supplement shield block, for the F32B-CBS basket, and the optional Not-Important-to-Safety (NITS) shielding port block, for the F12P-CBS basket, that are shown on drawing Nos. 15305 and 15624, respectively.
The ITS supplemental shield block is identified as Item 3 on drawing 15305 for the F32B-CBS basket. Explain the purpose of this item, provide its exact dimensions, location, and to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 6 of 25
attachment details. If not included in structural or shielding analyses, justify why they are not required especially for a HAC drop condition structural analysis. It is noted by staff that a similar block exists for the non-CBS version of this basket but is shrouded in aluminum; explain why the blocks employed for the CBS basket do not require this treatment.
The optional NITS shielding port blocks are identified in flag note 8 of drawing No.
15624. Identify the following: the purpose of this item, what parameter triggers the need for its use, the maximum quantity permitted, the block dimensions, and the attachment details. Advise whether its presence has been included in any structural or shielding analyses included in the application package, and if not, justify how these analyses are not required, especially a structural analysis during HAC drop conditions.
Verify for both the ITS shield blocks and the NITS port blocks, that their presence is accounted for in the maximum tabulated weights for each basket.
This information is required to satisfy the requirements of 10 CFR 71.41(a).
Holtec Response ITS supplemental shield blocks identified as item 3 on drawing No. 15305 for the F32B-CBS basket are credited as contributing to package shielding during transportation.
Dimensions, location, fastener size, type and quantity are added to Revision 3 of drawing No. 15305. The blocks are included in shielding analysis report HI-2167211 revision 9.
Explicit evaluation of the ITS shield blocks is added to structural report HI-2156553 (see Calculation 26).
The similar shield blocks illustrated as item 20 on F32B (welded) basket drawing 9797 are [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
] shield block details provide satisfactory heat conduction for the application, while maintaining essentially the same shielding capability.
The NITS shielding port blocks referenced by flag note 8 on CBS Basket drawings 15305 and 15625 are not credited in shielding analysis for transportation and are only used to mitigate worker dose in the furtherance of ALARA goals. The NITS shielding blocks strategically add a small mass of shielding material [ PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]. The purchaser may elect to include or omit this NITS item, as it suits the needs of their plant specific ALARA program.
This approach is the same as the optional NITS shielding blocks described in Note 17 on F12P drawing 9796 and F32B drawing 9797. Revision 0 of the NRC Certificate of Compliance No. 9374 for the HI-STAR 80 package, issued in 2018, references Revision 4 of drawings 9796 and 9797, which include the option for this NITS shielding block, and remains unchanged in the current drawings.
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Although no maximum quantity of shield blocks is explicitly listed on the drawings, the maximum quantity is limited by weight. No increase in the total basket weight or package weight is permitted if utilizing optional NITS shield blocks, then weight tolerances on other components must be tightened to accommodate it. The specific dimensions were omitted from the license drawings since the block is not credited in any analysis, and its size is constrained by the interior dimensions of the corner shim. The current fabrication drawing for the F32B-CBS basket specifies [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]. The current fabrication drawing for the F12P-CBS basket specifies
[PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]. Attachment is made using [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390].
Current fabrication drawings specify
[PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] locking plates.
Screw heads and locking plates are recessed below the [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390].
The NITS shielding blocks are not included in any structural or shielding analysis included in the application package. [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
] maximum bounding weight for the NITS shield blocks, is very low compared to a single fuel assembly. Should the block become detached, its effects on adjacent Metamic HT panels will be less severe and well bounded by the analyzed effects of fuel assemblies impacting Metamic HT panels; no gross deformation of Metamic HT panels is credible. In addition, the Metamic HT panels protect fuel assemblies from damage caused by the hypothetical detached shielding block.
Should the block become detached, any damage it imparts on the shim will be effectively self limited, as the shim is well supported by the steel cask containment boundary shell.
The possibility of detached shield block causing localized deformations and/or localized coating loss on the adjacent Metamic HT panels and shims are tolerable, and do not challenge the structural integrity of the basket or the fuel.
The bounding basket weights listed in SAR Table 2.1.9 include the weight of the ITS and NITS shield blocks.
RAI 2-7.
Justify or reconcile the following apparent inconsistencies in the licensing amendment application:
(A) SAR HI-2146261, Revision 6, table 1.1.4 refers to appendix 7.A for the last 2 listed package weight conditions. However, table 7.A.1 only addresses the weight of packaging with empty cask with the F-32B fuel basket; no entries address those with NFWB-1, F-12P, F-12P-CBS or F32B-CBS.
(B) The value for maximum package payload weight for F-12P/F-12P-CBS listed in SAR table 1.2.2, does not agree with that shown in table 2.1.9.
(C) The value for the PWR fuel cladding outer diameter listed in SAR table 2.6.8 does not agree with the value indicated in Supplement 14 to calculation report HI-2156553, Revision 10, Structural Calculation Package for the HI-STAR 80 Transport Cask System.
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(D)Section I.5.0 of calculation report HI-2167023, Revision 7, Finite Element Analysis of HI-STAR 80 Transport Package for Postulated Drop and Puncture Accidents, states that the F-12P fuel basket is pictured in figures I.7.1 to I.7.4, but they appear to depict the CBS version.
(E) Table I.8.2 of calculation report HI-2167023 indicates that the stress contour shown in figure I.8.3.3 depicts the Primary Membrane + Bending stress type, but it does not appear to do so, nor does it appear to display the stress intensity value of 43.52 ksi indicated in the Table.
(F) The allowable and computed crush depths of the impact limiters resulting from the 9-m free drop of the F12P-CBS basket is presented in SAR table 2.7.3B, however no commensurate results are presented in appendix I of calculation report HI-2167023, which documents this analysis. Provide the source of the crush depth data published in SAR table 2.7.3B.
In order for accurate conclusions to be reached for each transportation condition for which the package is evaluated, it is critical that the correct associated input parameters, analysis results and safety margins be presented in the submitted documentation.
This information is required to satisfy the requirements of 10 CFR 71.33(a)(2), 71.41(a),
and 71.55(e).
Holtec Response The apparent inconsistencies in the LAR are addressed below:
(A) Table 7.A.1 has been revised to address the weight of the packaging with NFWB-1, F-12P, F12P-CBS and F32B-CBS.
(B) The maximum package payload for the F-12P/F12P-CBS in Table 1.2.2 has been updated to match the value in Table 2.1.9.
(C) The correct value for the PWR fuel cladding outer diameter is [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390] which is used as input in Supplement 14 to calculation report HI-2156553. Table 2.6.8 incorrectly listed the fuel pellet OD, not the fuel cladding OD. This error has been corrected in the updated submittal.
(D) The F12P-CBS fuel basket is pictured in Figures I.7.1 to I.7.4. The statement in section I.5.0 of calculation report HI-2167023 has been corrected.
(E) Figure I.8.3.3 plots the maximum shear stress in the HI-STAR 80 containment shell for the 30-foot slapdown drop. Since stress intensity is equal to two times the maximum shear stress at a point, this figure can be used to obtain the maximum primary membrane stress intensity in the containment shell, as well as the maximum primary membrane plus bending stress intensity. As indicated below the figure title, the maximum primary membrane stress intensity is conservatively set at 38.38 ksi (= 2 x 19.19 ksi) based on the fringe levels associated with the contour plot. Using the same approach, the maximum primary membrane plus bending stress in the containment shell is conservatively set at 47.52 ksi (= 2 x 23.76 ksi) in Table I.6.2 (even though it to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 9 of 25
is not indicated in Figure I.8.3.3). The maximum primary membrane plus bending stress intensity only excludes the highest fringe level (shown in red in Figure I.8.3.3),
which is more localized and therefore characteristic of a secondary stress intensity (versus a primary stress intensity). Figure I.8.3.3 has been revised to clearly indicate the primary membrane plus bending stress intensity in the containment shell, as well as the primary membrane stress intensity.
(F) Appendix I of calculation report HI-2167023 has been revised to include the basis for crush depth data presented in SAR Table 2.7.3B. Refer to Table I.6.4 of HI-2167023 revision 8.
RAI 2-8.
Justify the revision of flag note 22 on drawing 9800, Revision 14, HI-STAR 80 Cask, which permits localized material thickness deviations in ITS cask components such as structural forgings and shielding.
Although the description of the note change indicates it only applies to certain trademarked enclosure materials, flag note 22 applies to more ITS cask components than these materials.
Additionally, the note is expanded from allowing a nominal thickness reduction over an equal amount of the surface area, to allow up to a five times that reduction over one fifth of the surface area. A significant reduction in thickness in localized areas of shielding and structures may result in unanalyzed conditions which may not comply with the requirements of 10 CFR Part 71.
This information is required to satisfy the requirements of 10 CFR 71.41(a).
Holtec Response Flag note 22 on cask drawing 9800 is reverted to the wording found in Revision 6 through Revision 13. Note that no new dimensions have invoked flag note 22 since DWG 9800 Revision 7, which was referenced in Revision 0 of the NRC Certificate of Compliance No.
9374 for the HI-STAR 80 package, issued in 2018.
With manufacturing experience, it is recognized that the flexibility of this extra provision is not needed, and therefore not worth further investigation and/or calculations.
RAI 2-9.
Justify the revision of note 18 on drawing No. 9800, Revision 14, HI-STAR 80 Cask, which permits the addition of NITS or ITS welds subject to Holtec engineering approval.
Allowing the addition of ITS welds may change the structural or other technical analysis assumptions for ITS components that form the safety evaluation basis for the license approval of the HI-STAR 80 transport package. Therefore, a justification for this proposed change is required.
This information is required to satisfy the requirements of 10 CFR 71.33(a)(5) and 71.41(a).
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Holtec Response Note 18 on drawing 9800 is clarified to read: Additional NITS welds may be added with approval of Holtec Engineering.
All ITS welds are shown or described on drawing 9800, and no new or novel ITS welds will be installed. The prior wording of Note 18 in drawing Revision 13 was unnecessarily specific, and the Revision 14 wording was not intended to authorize the addition of important-to-safety welds. This clarification confirms that the scope of ITS welds remains unchanged and that only NITS welds may be added with appropriate engineering approval.
RAI 2-10.
Verify that in the drop analyses of the cask containing the F-12P-CBS basket documented in appendix I of calculation report HI-2167023, Revision 7, Finite Element Analysis of HI-STAR 80 Transport Package for Postulated Drop and Puncture Accidents, the shim material is modeled as American Society for Testing and Materials (ASTM) B221 6063 at the appropriate temperature. Additionally, provide the strain rate values considered for each material in the analysis, as mentioned in section I.5.0 of the calculation report.
The CBS shim material is noted as being ASTM B221 6063 on basket drawing Nos. 15305 and 15624, and appendix B of report HI-2167023 was updated to include a true stress-strain curve for this material at 230°C. Therefore, it seems evident that the LS-DYNA drop analyses modeled the CBS shims as the 6063 material but requires written confirmation.
Staff notes that the reference in appendix B to table 3.III.3A of the HI-STORM 100 SAR for the 6063 material properties is no longer valid, as this table was deleted in the last SAR revision; it is recommended the material properties information be provided in this SAR.
Documentation of the strain rates considered for each material in the LS-DYNA analysis model is required to determine whether the values are appropriate for the type of dynamic event being simulated.
This information is required to satisfy the requirements of 10 CFR 71.33(a)(5)(iii),
71.55(e), and 71.73.
Holtec Response Holtec confirms that, for the LS-DYNA drop analyses for the cask containing the F-12P-CBS basket, the basket shims are modeled as ASTM B221 6063 material consistent with drawing 15624. A statement has been added in section I.4.4 of calculation report HI-2167023 to clearly indicate the basket shim material as ASTM B221 6063, along with a reference to Appendix B of the report for the precise numerical inputs. In addition, the material property data for ASTM B221 6063 has been added to the HI-STAR SAR 80 SAR in Table 2.2.12, and the reference in Appendix B of calculation report HI-2167023 has been revised accordingly. Lastly, section I.5.0 in HI-2167023 has also been updated to include the strain rate data used as input to the LS-DYNA drop analyses of the cask containing the F-12P-CBS basket.
Chapter 4: Containment Evaluation The applicant described the containment system components in SAR section 4.1 and provided SAR figure 4.1.1 for view of the HI-STAR 80 package containment boundary and containment system components. to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 11 of 25 RAI 4-1.
ANSI N14.5, American National Standard for Radioactive Materials - Leakage Tests on Packages for Shipment, defines the containment system as the assembly of the components that comprise the packaging intended to retain the radioactive material (radioactive contents) during transport, and the containment boundary as the designated boundary of the containment system, which is designed to prevent leakage of radioactive material.
(A) The applicant needs to identify the containment boundary components from the containment system for containment analysis, in accordance with ANSI N14.5.
The applicant included bolts, located at inner closure lid, outer closure lid, and cover plate of the spray cooling port, as the containment system components and categorized these bolts as containment under Part Function and important to safety (ITS) under Safety Category of the BILL OF MATERIAL - HI-STAR 80 (SAR Drawing No. 9800).
However, ANSI N14.5 notes that the containment boundary may include the containment vessel shell, welds, seals, lids, cover plates, and valves. This basically means items that are in contact with the fluid being contained, and the bolts, at inner closure lid, outer closure lid, and spray cooling port cover plate, are not in contact with the fluid. These bolts may serve as part of the closure system that compresses the containment boundary O-rings, which are part of the containment boundary.
(B) The applicant needs to clarify whether the closure bolts associated with inner closure lid, outer closure lid and cover plate of the spray cooling port are part of the containment system/boundary components. The applicant may need to revise/update the BILL OF THE MATERIAL in SAR Drawing No. 9800.
This information is required to determine compliance with 10 CFR 71.33 and 71.51.
Holtec Response (A) The BOM of Drawing 9800 is revised and the PART FUNCTION of items #5, #20,
- 25, #29, #53, #70, #74, #82 and #83 is indicated as "STRUCTURAL". The containment boundary description in Section 4.1 is revised accordingly.
(B) The following note is added to Chapter 4: The bolts serve as a structural function to secure the containment lids but do not directly contact the contained fluid. Therefore, in accordance with the ANSI N14.5 definition, the bolts are not considered part of the primary containment boundary.
The applicant stated, in SAR section 4.5.2.6, that the in-leakage evaluation over one year under normal conditions was performed using parameters in SAR table 4.5.2(a),
equation 4-6a, and methodology from subsection D.15.4 of ISO 12807: 2018(E), Safe Transport of Radioactive Material - Leakage Testing on Packages.
(A) The applicant needs to provide subsection D.15.4 of the ISO 12807:
2018(E) and calculations of the package cavity internal pressure (e.g., Excel sheet) for verification of the in-leakage evaluation for transport of the HI-STAR 80 package loaded with the non-fuel waste basket (NFWB package) and (B) clarify use of the to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 12 of 25 RAI 4-2.
minimum ambient pressure (Pext.min), a parameter tabulated in SAR table 4.5.2(a),
Parameters for In-leakage Calculation for in-leakage evaluation.
The applicant included the minimum ambient pressure (Pext.min) in SAR table 4.5.2(a), but Pext.min is not used in equation 4-6a for derivation of the internal pressure, as shown in SAR section 4.5.2.6.
(B) Clarify whether Pext.min is used for in-leakage evaluation and use of the Pext.min for in-leakage evaluation.
This information is required to determine compliance with 10 CFR 71.35.
Holtec Response (A) The in-leakage evaluation was performed using the methodology outlined in ISO 12807:2018, subsection D.15.4. This subsection will be submitted separately under proprietary documentation. The MATHCAD file is the calculation file used to determine internal pressure over time will also be submitted.
(B) The initial internal pressure of the containment cavity is set at [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390], and the in-leakage over a one-year period leads to a pressure rise calculated at [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]. This resulting internal pressure remains below the minimum ambient pressure, [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]..
Thus, Pext.min serves as a reference boundary condition in verifying containment integrity. This allows the evaluation to confirm that the internal pressure remains below ambient, ensuring containment integrity by design and justifying that viscous out-leakage is physically excluded under normal conditions of transport.
The applicant evaluated an internal cavity pressure (SAR table 4.5.2(b)) over one year due to in-leakage prior to shipment that would remain below the minimum possible ambient pressure (1 atm). The staff noted that in-leakage of the air keeps the package at negative pressure (below 1 atm) and out-leakage occurs only in HAC.
However, the applicant included both NCT and HAC allowable release rates and leakage rates at the upstream pressure in SAR table 4.5.7 but only provided the calculated HAC allowable leak rates at reference test conditions in SAR table 4.5.8 for the NFWB package.
(A)
Clarify whether out-leakage would occur to the NFWB package under normal conditions of transport (NCT, on-route shipment) and how the allowable NCT release rates and leakage rates, provided in SAR Table 4.5.7, are calculated if the out-leakage only occurs to the NFWB package under HAC.
(B)
If the out-leakage could occur under NCT(on-route shipment), then the applicant needs to provide the calculated NCT allowable leak rates at reference test conditions in SAR Table 4.5.8 for each backfill gas of air, helium, and nitrogen and the bounding NCT reference air leak rate in SAR Table 8.1.1 for the NFWB package. Calculation of the allowable NCT leak rate may need to account for the increased package internal pressure due to in-leakage prior to shipment. to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 13 of 25 RAI 4-3.
This information is required to determine compliance with 10 CFR 71.35 and 71.51.
Holtec Response (A) Out-leakage from the HI-STAR 80 package does not occur under Normal Conditions of Transport (NCT). As evaluated in Appendix A of containment report HI-2167204, the internal cavity pressure remains sub-atmospheric for one year due to in-leakage, with maximum pressure not exceeding [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]. This means there is no driving force to cause radioactive release during NCT. Therefore, the allowable release and leakage rates provided in SAR Table 4.5.7 are calculated assuming that out-leakage occurs only under Hypothetical Accident Conditions (HAC), not during NCT.
(B) According to Tables A-1 and A-2 of HI-2167204, [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]. These results clearly show that the internal pressure rise is evaluated and taken into account. Because the internal pressure remains below ambient pressure, out-leakage during Normal Conditions of Transport (NCT) is not possible. Appendix A of HI-2167204 confirms that, even after one year of in-leakage, the pressure is not high enough to cause a release.
Therefore, the allowable leak rates shown in Table 4.5.8 of the SAR apply only to Hypothetical Accident Conditions (HAC), since only those conditions can create a positive pressure inside the cask that could lead to out-leakage.
Chapter 7: Materials Evaluation RAI 7-1.
Provide the source for the thermal properties of aluminum alloy 6063. SAR Change 6 adds aluminum 6063 to table 3.2.1, Summary of HI-STAR 80 Packaging Materials Thermal Property References, and refers to reference 3.2.12, Aluminum Alloy 2219 Material Data Sheet, ASM Aerospace Specification Metals, Inc., Pompano Beach, Florida, for materials properties. This reference describes aluminum alloy 2219 but not 6063. Staff requires the actual reference that applicant used for the thermal properties to evaluate the alternate material.
This information is necessary to demonstrate compliance with 10 CFR 71.31(c),
71.33(a)(5), and 71.43(f).
Holtec Response The thermal properties of aluminum alloys 6063 and 2219 are both sourced from reference 3.2.12 in SAR Chapter 3. Although the title of reference 3.2.12 previously specified only aluminum alloy 2219, the reference document contains material property data applicable to both alloys. To eliminate confusion, reference 3.2.12 has been updated in the SAR to remove the explicit mention of 2219 from the title, clarifying that it is applicable to both aluminum alloy 6063 and aluminum alloy 2219.
RAI 7-2.
Provide the mechanical properties for aluminum alloy 6063 used in the structural analysis.
SAR Change 6 specifies aluminum alloy 6063 for the shims in the CBS baskets. SAR section 2.2.1.2.3 refers to table 2.2.7, Basket Shims - Nominal Mechanical Properties, for to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 14 of 25
the material properties of the CBS shims, but this table only lists properties for aluminum alloy 2219. Likewise, table 2.1.12, Critical Characteristics of the HI-STAR 80 Package Materials, only lists properties for aluminum alloy 2219. Enclosure 5 of the submittal, Finite Element Analysis of HI-STAR 80 Transport Package for Postulated Drop and Puncture Accidents, refers to table 3.III.3A, Alternative Fuel Basket Shim Material -
Nominal Mechanical Properties, of HI-STORM 100 final safety analysis report (FSAR) for mechanical properties of aluminum alloy 6063, but this table has been removed in the latest revision of the HI-STORM 100 FSAR. This information is needed for the staff to evaluate the new material.
This information is necessary to demonstrate compliance with 10 CFR 71.31(c),
71.33(a)(5), 71.43(f) and 71.55(d).
Holtec Response As discussed in the response to RAI 2-10, the material property data for ASTM B221 6063 has been added to the HI-STAR SAR 80 SAR in Table 2.2.12 and the reference in Appendix B of calculation report HI-2167023 has been revised accordingly.
RAI 7-3.
Provide the material specification, and if necessary, the thermal and mechanical properties for the Supplemental Shield Block. SAR Drawing 15305 shows item 3, Supplemental Shield Block, and identifies it as important to safety, yet provides no material specification.
This specification is needed for the staff to evaluate the new design.
This information is necessary to demonstrate compliance with 10 CFR 71.31(c),
71.33(a)(5), 71.43(d) and 71.51(a).
Holtec Response Permitted material specifications are added to drawing 15305. Various grades of ASME Section II compliant stainless steel are permitted. The bounding lower strength grade is considered for structural analysis. A representative grade is selected for shielding and thermal analysis, as the differences between grades are negligible from a shielding and thermal perspectives.
RAI 7-4.
Provide material properties and bolt specifications for the important to safety fasteners used to affix the CBS shims to the baskets in SAR Change 6 or justify the omission of this information. Flag note 6 on drawings 15305 and 15624 lists several potential specifications for these fasteners, but section 2.2 of the SAR does not include materials properties for these fasteners. The drawing also fails to specify bolt size or type. This specification is needed for the staff to evaluate the new design.
This information is necessary to demonstrate compliance with 10 CFR 71.31(c),
71.33(a)(5), and 71.43(d) and (f).
Holtec Response The material list for bolts and nuts joining Metamic HT panels and aluminum shims is clarified on CBS basket drawings 15305 and 15624. The revised list will include
[PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390]. Fastener to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 15 of 25
dimensions are in accordance with the fastener specification (A193, etc), or are in compliance with the applicable ASME B18 series standard for the fastener type.
Properties for these materials are included in SAR Tables 2.2.4 and 2.2.6 (Note that, the A193 standard uses the grade designation [PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390].)
Bolt minimum sizes and minimum quantities are added to drawings 15305 and 15624.
Chapter 8: Package Operations
Background:
Proposed Revision 6 of the HI-STAR 80 SAR introduces new fuel basket configurations (F-12P-CBS and F-32B-CBS) that incorporate CBS. However, chapter 7 of the SAR does not describe specific operational steps for verifying the presence, condition, or provide direction for confirming that the correct basket model (CBS vs non-CBS) is installed.
Request for Additional Information:
RAI 8-1.
Please clarify whether any operational steps are required to identify and verify the installed fuel basket model (e.g., CBS vs. non-CBS), and whether that identification is performed during receipt inspection to ensure the correct loading configuration is selected.
Additionally, please clarify whether any operational steps are required to verify that the CBS attachment bolts are secured such that the basket panels remain properly aligned prior to loading or transport.
If no basket model verification, alignment check, or other CBS-specific steps are needed, please provide justification that the existing chapter 7 operational steps bound the CBS basket configurations and that no additional checks are necessary to ensure safe handling and regulatory compliance.
This information is needed to demonstrate compliance with 10 CFR 71.87.
Holtec Response A requirement for model verification is added to SAR Chapter 7, section 7.1.1, Step 9, concurrent with or preceding basket panel visual check for damage. This step must be completed prior to loading fuel. An exemption is permitted if the supply of the incorrect model is not possible; for example, if the cask owner only possesses one model of basket.
A specific check to distinguish between BWR and PWR baskets is not needed; the number and size of cells are very different and not easily confused.
No specific inspection of CBS bolts is required. No credible failure mechanisms exist during normal conditions of transportation or fuel loading, unloading, basket handling, and cleaning. Welds or other mechanical means are used to prevent bolts from loosening, and no pre-load or pre-tension is required for this application. In the hypothetical situation of a bolt breaking and coming out of its hole, the pieces would be apparent during foreign material checks prior to loading fuel.
The F12P-CBS and F32B-CBS baskets maintain full retention and alignment of all components by design and are not subject to alignment checks after insertion into the HI-to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 16 of 25
STAR 80 cask. The baskets are designed for lifting and handling as a single piece, for insertion and removal from the cask, to facilitate the use of different basket types depending on the intended payload for transport. [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
], it will stop lowering, more than 12 feet before full insertion, which would be very visually apparent, and would physically block installation of the lids.
RAI 8-2.
Please clarify whether torque specifications, installation criteria, or inspection requirements exist for CBS attachment bolts to the fuel basket panels. Specifically, identify whether bolt torque values are defined, measured, or verified during fabrication, and whether acceptance criteria or quality assurance controls are used to ensure the bolts are properly installed and secured.
If no torque requirements or verification steps are specified, please provide justification that the CBS attachment bolts will maintain its intended performance under normal conditions of transport and handling without the need for ongoing surveillance or maintenance.
This information is needed to demonstrate compliance with 10 CFR 71.87.
Holtec Response The response to RAI 2-3 details the functionality of the CBS attachment bolts, and explains that they are not in the load path supporting fuel during any hypothetical accident condition.
Installation criteria for CBS attachment bolts are not critical to the performance of the basket. No tightening torque is specified (fabrication drawings specify tightening to achieve wrench tight condition). Bolt installation is validated indirectly by (a) conformation of the basket outside diameter, which is provided with tolerance on CBS basket license drawings 15305 and 15624, (b) installation of welds between the bolt and nut (or equivalent) to prevent un-threading of the fastener pair. The bolt and nut must be sufficiently engaged to provide the surfaces joined in the weld, and the completed welds are inspected in accordance with quality procedures. To support this response, Additional Note 10 is added to CBS basket drawings 15305 and 15624 to clarify the requirement for welds between the bolts and nuts No credible failure modes exist for bolts during the normal conditions of transport, or during short term loading, unloading operations, or during transport without fuel present.
Bolt loads during basket handling are relatively light, bolts have a degree of redundancy, and handling cycles too few to make fatigue concerns credible. Basket handling is performed without fuel in the cask. With no credible failure modes, paired with tolerable consequences of hypothetical bolt failure, no ongoing inspection program is warranted. In the hypothetical case of bolt failure, it is expected that the bolt would be discovered during FME inspections prior to loading fuel. The FME inspections provide an indirect surveillance over the life of the basket.
RAI 8-3.
Provide derivations of the changes made in SAR table 7.1.5, clarify the guidance for use of the mixed tracer gases of air and helium, and provide the allowable NCT and HAC reference argon leak rates, as addressed in items (A), (B), and (C) below.
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The staff compared table 7.1.5 of the SAR used for this amendment application to table 7.1.5 of the previous SAR, Revision 5, 2023 (Holtec Report HI-2146261) for cask backfill requirements for the NFWB package and noted that the pressure ranges are changed from 20 kPa - 200 kPa (Revision 5) to 20 kPa - 40.6 kPa (SAR) for cask cavity space, from 0 kPa - 17.2 kPa (Revision 5) to 20 kPa - 40.6 kPa (SAR) for cask inter-lid space, and from atmospheric pressure (Revision 5) to atmospheric or sub-atmospheric pressure (SAR) for orifice port space.
(A) The applicant needs to provide derivations on the revised pressure ranges, made in SAR table 7.1.5, for cask cavity space and cask inter-lid space. Explain change of the pressure range in orifice port space.
The applicant noted, in SAR table 7.1.5, that air backfill may include helium as desired to facilitate leak testing (Note #4 in table 7.1.5) and nitrogen or argon may be used in place of air (Note #5 in table 7.1.5).
(B) The applicant needs to clarify for Note #4 that the guidance in section A.3.6, Tracer Gas Partial Pressure of ANSI N14.5, will be followed and that partial pressure of the tracer gas in the test mixture (a mixture of air and helium) should be at least 10 percent of the total pressure and must be known (C) The applicant needs to provide the allowable NCT and HAC reference argon leak rates in SAR table 4.5.8 for use of argon in place of air (Note #5 in SAR table 7.1.5) or clarify that argon is bounded by other gases.
This information is required to determine compliance with 10 CFR 71.51.
Holtec Response The cask backfill requirements for shipment of non-fuel waste were changed in revision 6 of the SAR for both the Cask Cavity Space and the Cask Inter-Lid Space to ensure that both of these regions always remain under a partial vacuum (sub-atmospheric) under normal conditions of transport, as described in SAR Section 4.5.2. This change was desirable to improve containment by removing the possibility of outwards leakage under normal conditions of transport.
The Orifice Port Space pressure requirement was changed to allow for sub-atmospheric pressure, as it may be found that this provides operational improvements. If, for instance, the cask user plans to use helium in this space, it may be difficult to ensure that the gas is supplied at precisely atmospheric pressure as required in SAR revision 5. Therefore, the Orifice Port Space pressure range in Table 7.1.5 of SAR revision 6 may allow for simplified operations.
The backfill gas in this space provides no heat transfer function for shipment of non-fuel waste and so changes to pressure in this space do not impact overall cask heat transfer.
Note #4 of SAR Table 7.1.5 will be modified to clarify that a minimum of 10% tracer gas must be included to facilitate leak test per ANSI N14.5, except where alternate leak test methods which do not require helium are to be used, as allowed by SAR Table 8.1.2 Note #3.
SAR Chapter 4 will be updated to clarify that argon leak rates are bounded by those of the other allowed backfill gas. to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 18 of 25
Chapter 9: Acceptance Tests and Maintenance Program RAI 9-1.
Explain why the summation of individual component leakage rates of the containment boundary of a package is not required for the HI-STAR 80 package which is not defined as a leaktight package in this amendment application (SAR, Revision 6)
The applicant specified the components of the containment system in SAR, section 4.1, and stated, in Note #1 of the SAR, table 8.1.2, that for a leakage rate acceptance criterion, the summation of individual component leakage rates of the containment boundary of a package is not required.
According to leakage test requirements described in section 7.1 of the ANSI N14.5: (A)
Except for packages with a leaktight criterion, the leakage rates for individually tested components shall be summed and (B) the component leakage tests of the containment boundary of packages with a leaktight criterion need only be shown individually to be leaktight and the summation of individual component leakage rates of the containment boundary of a package with a leaktight criterion is not required.
The staff referred to the allowable leakage rates in SAR tables 8.1.1 and 8.1.2 and finds that the HI-STAR 80 package, used for transport of fuels (e.g., F-12P, F12P-CBS, F-32B, and F32B-CBS) or non-fuel waste, is not defined as a leaktight package and therefore the leakage rates for individually tested components shall be summed, in accordance with ANSI N14.5.
The applicant needs to explain why the summation of individual component leakage rates of the containment boundary is not required for the non-leaktight HI-STAR 80 package, consistent with ANSI N14.5.
This information is required to determine compliance with 10 CFR 71.51.
Holtec Response Summary of Changes:
The text of SAR Table 8.1.2 Note 1 will be updated to read as follows:
For a Leakage Rate Acceptance Criterion, the summation of individual component leakage rates of the containment boundary of a package is required.
For the purposes of summation, the containment boundary shall include the more conservative (higher measured leakage rate) of either the inner or outer containment boundary closure components at each closure location, except as allowed by Note 2 of this table. An alternative (more stringent) acceptance criterion of 1x10-7 ref-cm3/s air (leak tight as defined by ANSI N14.5) may be applied. If this alterative acceptance criterion is applied, leak rate for all tested components need not be summed.
SAR Table 8.1.2 Note 1 currently applies to Fabrication, Maintenance, and Periodic Leakage Rate Tests in Table 8.1.2. Table 8.1.2 will be updated to also apply Note 1 to the Pre-Shipment Leakage Rate Test, so that summation will now be required for all leakage rate tests in Table 8.1.2. to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 19 of 25
Explanation of Changes:
In order to ensure consistency with ANSI N14.5 Section 7.1, Note 1 of SAR Table 8.1.2 will be updated to state that for a leakage rate acceptance criterion, the summation of individual component leakage rates of the containment boundary of a package is required.
Further clarification will also be added to Note 1 of Table 8.1.2 to state that an alternative (more stringent) acceptance criterion of 1x10-7 ref-cm3/s air (leak tight as defined by ANSI N14.5) may be applied. If this alterative acceptance criterion is applied, the leak rate for all tested components does not need to be summed.
Further clarification will also be added to Note 1 of Table 8.1.2 to state that for the purposes of summation, the containment boundary shall include the more conservative (higher measured leakage rate) of either the inner or outer containment boundary closure components at each closure location. This requirement does not apply to pre-shipment and periodic leakage rate tests for MBF and NFW, where only one of the two (inner or outer) barriers is required to be tested.
For clarity, Figure 1 below provides an example illustration of the inner and outer containment boundary closure components. [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390 ] This means that in practice, the actual total leakage rate at this closure location will be conservatively bounded by the measured leakage rate of the highest-leakage rate barrier, even in the event of a single seal failure.
Table 1 below provides a detailed overview of how these requirements apply to the inner and outer closure components at each closure location. In addition, Table 2 and Table 3 provide example leakage test results and an example calculation of the package leakage rate total in accordance with these results.
[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
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[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
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[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
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[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
RAI 9-2.
Explain removal of both inner closure lid retainer ring and inner closure lid leak test port primary helical thread insert from the fabrication leakage rate test and the maintenance leakage rate test in SAR table 8.1.2, Leakage Rate Tests for the HI-STAR 80 Containment System.
The staff reviewed changes made in SAR table 8.1.2 and finds that both inner closure lid retainer ring and inner closure lid leak test port primary helical thread insert are removed from fabrication leakage rate test and maintenance leakage rate test in this amendment application (SAR) when compared to table 8.1.2 of SAR, Revision 5 (2023).
Given that both inner closure lid retainer ring and inner closure lid leak test port primary helical thread insert are identified as important to safety (ITS) under Safety Category and containment under Part Function of the BILL OF MATERIAL - HI-STAR 80 (SAR Drawing No. 9800, Sheet 2 of 12), the applicant needs to explain removal of these two containment components from the fabrication leakage rate test and the maintenance leakage rate test The staff needs information to identify the containment system and ensure the entire containment system/boundary is leak tested.
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This information is required to determine compliance with 10 CFR 71.33 and 71.51.
Holtec Response The Bill of Material of Drawing 9800 is revised to change the Part Function of items #5,
- 20, #25, #29, #53, #70, #74, #82 and #83 to STRUCTURAL. This is done for consistency with the definitions in 2014 ANSI N14.5, with only components forming the fluid boundary classified as CONTAINMENT. The inner lid retainer ring, bolts, thread inserts, etc. are structurally necessary to support the containment components, but do not form part of the fluid boundary, and therefore do not require any leak testing.
No changes are made to SAR Table 8.1.2, as it is already consistent with the ANSI N14.5 convention.
In addition, please see the response to RAI 4-1.
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RAI 9-3.
Add test frequency in SAR, table 8.1.2, to fully address the requirements of the leakage tests, in accordance with ANSI N14.5.
Given that SAR, table 8.1.2, is a condition of the certificate of compliance (CoC), the applicant needs refer to table 1, Containment Boundary Test Requirements, of the ANSI N14.5 and add test frequency in SAR, table 8.1.2, to fully address the requirements of the leakage tests (e.g., fabrication, pre-shipment, maintenance, and periodic leak tests), in accordance with ANSI N14.5.
This information is required to determine compliance with 10 CFR 71.51.
Holtec Response The required frequencies of periodic and maintenance leakage rate tests are provided in SAR Table 8.2.1 and are explained further in SAR Section 8.2.2 as well as SAR Sections 4.4.3 and 4.4.4. SAR Table 8.2.1, including these test frequency requirements, is also provided as a condition of the CoC and is in alignment with the requirements of ANSI N14.5.
Fabrication leakage rate tests are only performed once as described in SAR Section 4.4.1 and do not have an applicable test frequency. Pre-shipment leakage rate tests are performed prior to each shipment as described in SAR Section 4.4.2 and 8.1.4, rather than being performed at a regular frequency. These requirements in the SAR are in alignment with the requirements of ANSI N14.5. to Holtec Letter 2370019-NRC NON-PROPRIETARY INFORMATION Page 25 of 25