ML25062A252
| ML25062A252 | |
| Person / Time | |
|---|---|
| Site: | 07201032 |
| Issue date: | 02/28/2025 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML25062A248 | List: |
| References | |
| 5018123, EPID L-2024-LLA-0020 | |
| Download: ML25062A252 (1) | |
Text
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 11C 1-72 1.2.3 Cask Contents This sub-section contains information on the cask contents pursuant to 10 CFR72, paragraphs 72.2(a)(1),(b) and 72.236(a),(c),(h),(m).
The HI-STORM FW System is designed to house both BWR and PWR spent nuclear fuel assemblies. Tables 1.2.1 and 1.2.2 provide key system data and parameters for the MPCs. A description of acceptable fuel assemblies for storage in the MPCs is provided in Section 2.1. This includes fuel assemblies classified as damaged fuel assemblies and fuel debris in accordance with the definitions of these terms in the Glossary. All fuel assemblies, non-fuel hardware, and neutron sources authorized for packaging in the MPCs must meet the fuel specifications provided in Section 2.1. All fuel assemblies classified as damaged fuel or fuel debris must be stored in damaged fuel containers (DFC) or fuel cell storage location equipped with a damaged fuel isolator (DFI) for damaged fuel that can be handled by normal means. Figure 2.1.7 shows a typical DFI.
As shown in Figure 1.2.1a (MPC-37) and Figure 1.2.2 (MPC-89), each storage location is assigned to one of three regions, denoted as Region 1, Region 2, and Region 3 with an associated cell identification number. For example, cell identified as 2-4 is Cell 4 in Region 2. A damaged fuel assembly in a DFC or using a DFI can be stored in the outer peripheral locations of the MPC-37/MPC-32ML/MPC-37P/MPC-44 and MPC-89 as shown in Figures 2.1.1 and 2.1.2, respectively.
The permissible heat loads for each cell, region, and the total canister are given in Tables 1.2.3a through Tables 1.2.3e and 1.2.4a through 1.2.4b for the MPC-37/MPC-32ML/MPC-37P/MPC-44 and MPC-89, respectively. The sub-design heat loads for each cell, region and total canister are in Table 4.4.11. New heat load patterns can be developed in accordance with the methodology in Section 4.4 of the FSAR. New patterns must satisfy the requirements in Tables 1.2.3f and 1.2.4c.
Table 1.2.9 specifies the HI-STORM FW overpacks, which can be loaded with MPCs that satisfy the requirements in Tables 1.2.3f and 1.2.4c.
As an alternative to the loading patterns discussed above, fuel storage in the MPC-37 and MPC-89 is permitted to use the heat load patterns shown in Figure 1.2.3 through Figure 1.2.5 (MPC-37) and Figures 1.2.6 and 1.2.7 (MPC-89).
slightly thermally-discrepant fuel assembly per quadrant to be loaded as long as the peak cladding temperature for the MPC remains below the ISG-11 Rev 3 is permitted for essential dry storage campaigns to support decommissioning.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 11C 1-81 Table 1.2.3f MAX. ALLOWABLE HEAT LOADS FOR PWR MPCs Notes 1,2 MPC Type Max. Allowable Total MPC Heat Load, kW Max. Allowable Heat Load per Storage Location, kW MPC-32ML 59.0 5.0 MPC-37 59.0 5.0 MPC-37P 59.0 5.0 MPC-44 59.0
5.0 Notes
(1) The maximum allowable heat loads presented in this table are for new heat load patterns developed using the methodology presented in Section 4.4. The maximum allowable heat load per storage cell for MPC-37 and MPC-44 are based on the active length of the standard-length fuel(Table 1.2.10). Maximum allowable heat load per storage location for fuels with shorter or longer active fuel lengths than the standard active fuel length should be determined using the methodology in Chapter 4.
(2) PWR MPCs permitted for use with the maximum allowable heat loads specified in the table above may only be used with the HI-STORM FW overpacks listed in Table 1.2.9.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 11C 1-84 Table 1.2.4c MAX. ALLOWABLE HEAT LOAD FOR THE MPC-89 Notes 1,2 MPC Type Max. Allowable Total MPC Heat Load, kW Max. Allowable Heat Load per Storage Location, kW MPC-89 60.8
2.7 Notes
(1) The maximum allowable heat loads presented in this table are for new MPC-89 heat load patterns developed using the methodology presented in Section 4.4. The maximum allowable heat load per storage cell for MPC-89 is based on the active length of the standard-length fuel (150 inches). Maximum allowable heat load per storage location for fuels with shorter or longer active fuels than the standard active fuel length should be determined using the methodology in Chapter 4.
(2) The MPC-89 with the maximum allowable heat load specified in the table above may only be used with the HI-STORM FW overpacks listed in Table 1.2.9.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 11C 1-90 TABLE 1.2.9 HI-STORM FW Overpack Versions Compatible with High Heat Load MPCs Overpack Version MPC Type HI-STORM FW Version E MPC-37, MPC-37CBS, MPC-37P, and MPC-89, MPC-89CBS HI-STORM FW Extended Configuration MPC-32ML, MPC-37, MPC-37CBS, MPC-44, and MPC-89 Table 1.2.9 Intentionally Deleted
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-108 Butterworth filter with a cut-off frequency of 350 Hz; the same filter was used for the HI-STORM 100 non-mechanistic tipover analysis. For the HI-STORM FW Version G, local plastic deformation is observed at the overpack top plate to pad interface, the lid top plate to pad interface and the bottom rib which stages the MPC as shown in Figures 3.4.17J and 3.4.17K. However, the shielding capacity of overpack will not be compromised by the tipover accident and there is no gross plastic deformation in the overpack inner shell to affect the retrievability of the MPC. In addition, the cask closure lid bolts are demonstrated to be structurally safe after the tipover event, and zero strain is observed in the bolt near the impact location (see Figures 3.4.18D & 3.4.18E). Therefore, the cask lid will not dislodge after the tipover event. Finally, the peak rigid body decelerations, measured for the HI-Case 2 in the horizontal direction (see Figures 3.4.20D & 3.4.20E). Note that the deceleration time histories are filtered using the LS-DYNA built-in Butterworth filter with a cut-off frequency of 350 Hz; the same filter was used for the HI-STORM 100 non-mechanistic tipover analysis. For Version G, Figure 3.4.19J to 3.4.19K and Figure 3.4.20J to 3.4.20K present the deceleration time history results of the cask lid predicted by LS-DYNA. The peak rigid body decelerations measured for the HI-horizontal direction, respectively. The bounding horizonal deceleration of the lid coincident with the The non-mechanistic tipover analysis for HI-STORM FW Version E cask is performed in [3.4.30]
using the same method used for HI-STORM FW cask in [3.4.11], and it is demonstrated in [3.4.30]
that all of the acceptance criteria discussed above, and more precisely defined in Subsection 2.2.8, are satisfied. The maximum permanent lateral deflection of the most heavily loaded basket panel, at any elevation within the active fuel region, is obtained from the LS-DYNA solutions and reported in Table 3.4.24 for the various fuel basket types. All calculated safety factors are above 1.0. Therefore, the Metamic-HT fuel baskets are considered to be structurally safe since they can continue maintaining appropriate spacing between fuel assemblies after the tipover event.
The non-mechanistic tipover analyseis for HI-STORM FW Version E cask with MPC-37 and MPC-89 under high heat loads (discussed in Section 1.2) areis performed in [3.4.30] using the same method used for the HI-STORM FW cask in [3.4.11], and it is demonstrated in [3.4.30] that all of the acceptance criteria discussed above, and more precisely defined in Subsection 2.2.8, are satisfied.
The maximum permanent lateral deflection of the most heavily loaded basket panel, at any elevation within the active fuel region, is obtained from the LS-DYNA solutions and reported in Table 3.4.28 for the various high heat load fuel basket types. All calculated safety factors are above 1.0.
Therefore, the Metamic-HT fuel baskets are considered to be structurally safe since they can continue maintaining appropriate spacing between fuel assemblies after the tipover event.
Finally, the structural analyses of the HI-STORM FW lids [3.4.13] are performed using bounding peak rigid body deceleration forces; therefore, the results are applicable to the non-mechanistic tipover event with target foundation concrete strength specified in Table 2.2.9. It is concluded that the lids will not suffer any gross loss of shielding and will remain attached to the cask bodies.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-109 The non-mechanistic tipover analysis for HI-STORM FW Version F cask with MPC-37 is performed in [3.4.31] using the same method used for HI-STORM FW cask in [3.4.11] and it is demonstrated in calculation package [3.4.31] that all of the acceptance criteria, discussed above, are satisfied.
The non-mechanistic tipover analyses for HI-STORM FW Version E1 cask loaded with MPC-37, MPC-89 and MPC-32ML fuel baskets are performed in [3.4.34] using the same method used for HI-STORM FW cask in [3.4.11], and it is demonstrated in [3.4.34] that all of the acceptance criteria discussed above, and more precisely defined in Subsection 2.2.8, are satisfied. Local plastic deformation is observed at the overpack top plate to pad interface and the Common lid top plate to pad interface as shown in Figures 3.4.17H. However, the shielding capacity of overpack will not be compromised by the tipover accident and there is no gross plastic deformation in the overpack inner shell to affect the retrievability of the MPC. The maximum primary membrane plus bending stress in the fuel basket panels, within the active fuel region, does not exceed 90% of the true ultimate strength of Metamic-HT material at the applicable temperature per Subsection 2.2.8. Refer to subparagraph 3.4.4.1.4e for further explanation and results. The maximum permanent lateral deflection of the most heavily loaded basket panel, at any elevation within the active fuel region, is obtained from the LS-DYNA solutions and reported in Table 3.4.27 for the various fuel basket types inside the HI-STORM FW Version E1 overpack. All calculated safety factors are above 1.0.
Therefore, the Metamic-HT fuel baskets are considered to be structurally safe since they can continue maintaining appropriate spacing between fuel assemblies after the tipover event.
The non-mechanistic tipover analysis for HI-STORM FW Version G cask with MPC-37 is performed in [3.4.36] using the same method used for HI-STORM FW cask in [3.4.11] and it is demonstrated in calculation package [3.4.35] that all of the acceptance criteria, discussed above, are satisfied.
The structural analyses of the HI-STORM FW Common lids ([3.4.32] and [3.4.34]) are performed using bounding peak rigid body deceleration and corresponding inertial forces. It is concluded that the Common lids will not suffer any gross loss of shielding and will remain attached to the cask bodies.
3.4.4.1.4b Load Case 4: Non-Mechanistic Tipover of MPC-89 CBS Basket Design
[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]For the ISFSI, the bounding target foundation properties per Table 2.2.9 areutilized.
[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
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HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-111 deceleration values; therefore, the lids do not suffer any gross loss of shielding.
Additionally, the use of elevated temperatures of 450oF or greater for cask body and lid in the LS-DYNA tipover models does not adversely impact the safety conclusions as demonstrated in [3.4.11].
The non-mechanistic tipover analyses for HI-STORM FW Version F cask with MPC-89 CBS fuel basket is presented in [3.4.31] using the same method used for standard baskets and it is demonstrated that all of the acceptance criteria, discussed above, are satisfied.
The non-mechanistic tipover analysies for HI-STORM FW Version E cask with MPC-89 CBS fuel basket under high heat load (discussed in Section 1.2) is presented in [3.4.30] using the same method used for standard baskets and it is demonstrated that all of the acceptance criteria, discussed above, and more precisely defined in Subsection 2.2.8, are satisfied. The complete details of the finite element model, input data and results are archived in the calculation package [3.4.30]. In summary, the results of the tipover analysis demonstrate that all safety criteria are satisfied for the HI-STORM FW Version E cask with MPC-89 CBS basket design under high heat load, which means:
- i. The permanent lateral deflection of the most heavily loaded basket panel in the active fuel region complies with the deflection criterion in Table 2.2.11 as presented in Table 3.4.28.
ii. The maximum primary membrane plus bending stress in the fuel basket panels, within the active fuel region, does not exceed 90% of the true ultimate strength of Metamic-HT material at the applicable temperature per Subsection 2.2.8. Refer to subparagraph 3.4.4.1.4e for further explanation and results.
iii. [
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
iv. The plastic strains in the MPC enclosure vessel remain below the allowable material plastic strain limit.
- v. The cask closure lid does not dislodge after the tipover event, i.e., the closure lid bolts remain in-tact.
vi. The structural analysis of cask closure lid is performed in [3.4.13] using bounding peak deceleration values; therefore, the lids do not suffer any gross loss of shielding.
The non-mechanistic tipover analysies for HI-STORM FW Version E1 cask with MPC-89 CBS fuel basket is presented in [3.4.34] using the same method used for standard baskets and it is demonstrated that all of the acceptance criteria, discussed above, and more precisely defined in Subsection 2.2.8, are satisfied. The complete details of the finite element model, input data and results are archived in the calculation package [3.4.34]. In summary, the results of the tipover analysis demonstrate that all safety criteria are satisfied for the HI-STORM FW Version E1 cask with MPC-89 CBS basket design, which means:
i.
The permanent lateral deflection of the most heavily loaded basket panel in the active fuel region complies with the deflection criterion in Table 2.2.11 as presented in Table 3.4.27.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-114
- a. MPC-37P CBS basket panels are thicker than that of MPC-37 CBS basket per licensing drawings in Section 1.5.
- b. MPC-37P CBS basket cell width is smaller than that of MPC-37 CBS basket per licensing drawings in Section 1.5.
- c. Weight of MPC-37P CBS fuel assemblies is conservatively bounded by MPC-37 fuel assemblies per Table 2.1.1.
- d. Temperature distribution of MPC-37P CBS basket panels is bounded by MPC-37 CBS basket panels per thermal analyses supporting Chapter 4.
The finite element model of the MPC-37 CBS basket is shown in Figure 3.4.12F. The details of the comparative evaluation, as well as the calculated results for the MPC-37 CBS tipover analysis, are documented in [3.4.30]. The maximum permanent deflection of the heaviest loaded fuel basket panel for the MPC-37/37P CBS basket is reported in Table 3.4.24. The stress distribution in the basket shims is plotted in Figure 3.4.68C, which shows that the stresses in the CBS are mainly below the material yield strength with only limited permanent deformation. Therefore, as the results demonstrate, the acceptance criteria defined in Paragraph 2.2.3(b) are satisfied for HI-STORM FW Version E cask with MPC-37P CBS basket.
The non-mechanistic tipover of HI-STORM FW Version E cask with MPC-37P CBS basket under high heat load (discussed in Section 1.2) inside is not explicitly analyzed because it is bounded by the tipover analysis of MPC-37 CBS basket for the reasons stated above. The non-mechanistic tipover analysis for HI-STORM FW Version E cask with MPC-37 CBS fuel basket under high heat load (discussed in Section 1.2) is presented in [3.4.30] using the same method used for standard baskets, and it is demonstrated that all of the acceptance criteria, discussed above, and more precisely defined in Subsection 2.2.8, are satisfied. The complete details of the finite element model, input data and results are archived in the calculation package [3.4.30]. In summary, the results of the tipover analysis demonstrate that all safety criteria are satisfied for the HI-STORM FW Version E cask with MPC-37 CBS basket design, which means:
i.
The permanent lateral deflection of the most heavily loaded basket panel in the active fuel region complies with the deflection criterion in Table 2.2.11 as presented in Table 3.4.28.
ii.
The maximum primary membrane plus bending stress in the fuel basket panels, within the active fuel region, does not exceed 90% of the true ultimate strength of Metamic-HT material at the applicable temperature per Subsection 2.2.8. Refer to subparagraph 3.4.4.1.4e for further explanation and results.
iii.
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PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
iv.
The plastic strains in the MPC enclosure vessel remain below the allowable material plastic strain limit.
v.
The cask closure lid does not dislodge after the tipover event, i.e., the closure lid bolts remain in-tact. The structural analysis of cask closure lid is performed in
[3.4.13] using bounding peak deceleration values; therefore, the lids do not suffer
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-115 any gross loss of shielding.
The non-mechanistic tipover of HI-STORM FW Version E1 cask with MPC-37P CBS basket inside is not explicitly analyzed because it is bounded by the tipover analysis of MPC-37 CBS basket for the reasons stated above. The non-mechanistic tipover analysis for HI-STORM FW Version E1 cask with MPC-37 CBS fuel basket is presented in [3.4.34] using the same method used for standard baskets, and it is demonstrated that all of the acceptance criteria, discussed above, and more precisely defined in Subsection 2.2.8, are satisfied. The complete details of the finite element model, input data and results are archived in the calculation package [3.4.34]. In summary, the results of the tipover analysis demonstrate that all safety criteria are satisfied for the HI-STORM FW Version E1 cask with MPC-37 CBS basket design, which means:
i.
The permanent lateral deflection of the most heavily loaded basket panel in the active fuel region complies with the deflection criterion in Table 2.2.11 as presented in Table 3.4.27.
ii.
The maximum primary membrane plus bending stress in the fuel basket panels, within the active fuel region, does not exceed 90% of the true ultimate strength of Metamic-HT material at the applicable temperature per Subsection 2.2.8. Refer to subparagraph 3.4.4.1.4e for further explanation and results.
iii.
[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
]
iv.
The plastic strains in the MPC enclosure vessel remain below the allowable material plastic strain limit.
v.
The cask closure lid does not dislodge after the tipover event, i.e., the closure lid bolts remain in-tact. The structural analysis of cask closure lid is performed in
[3.4.34] using bounding peak deceleration values; therefore, the lids do not suffer any gross loss of shielding.
3.4.4.1.4e Load Case 4: Stress Analysis of MPC Fuel Baskets During Non-Mechanistic Tipover The preceding subparagraphs, specifically 3.4.4.1.4a through 3.4.4.1.4d, show that the maximum permanent deflections of the fuel basket panels, due to a non-mechanistic tipover event, are below the allowable limit specified in Table 2.2.11 for various MPC and overpack pairings. Besides deflections, Subsection 2.2.8 also requires that the primary stresses in the fuel basket panels due to the non-mechanistic tipover event are below 90% of the true ultimate strength of the Metamic-HT material at the applicable temperature. This subparagraph summarizes the additional stress analyses performed for the most limiting MPC/overpack pairings and demonstrates compliance with the stress criterion for Metamic-HT fuel baskets, as stated in Subsection 2.2.8.
The tipover models used to predict the stress levels in the MPC fuel basket are identical to those used in the preceding subparagraphs to examine basket panel deflections, except for the following modeling refinements:
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-118
[
PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390
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To conclude, the entirety of the results for the MPC fuel baskets due to the non-mechanistic tipover event, including the stress results in Figures 3.4.70 through 3.4.73, as well as the deflection results in Tables 3.4.23 and 3.4.24, are below the allowable limits set forth in Subsection 2.2.8. This confirms that the fuel baskets will maintain their structural integrity following a hypothetical tipover event, and thus will preserve the criticality safety of the spent fuel storage array. This conclusion applies to the MPC types listed in Table 3.4.26, when they are loaded inside the standard HI-STORM FW or the HI-STORM FW Version E, as permitted by the CoC.
To meet the requirements stated above, the newly added HI-STORM FW Version E tipover analyses in [3.4.30] demonstrate that (i) the maximum permanent deflection in the fuel basket meets the specified limit in Table 2.2.11 (see discussion in preceding subparagraphs, specifically 3.4.4.1.4a, 3.4.4.1.4c and 3.4.4.1.4d) and (ii) the primary stresses in the fuel basket panels are below 90% of the true ultimate strength of the Metamic-HT material. Figure 3.4.77 shows the stress levels in the active fuel region for the governing fuel basket (i.e., MPC-37CBS) inside the HI-STORM FW Version E. The MPC-37CBS fuel basket is the governing basket as it has the lowestleast safety factor (per Table 3.4.28) for the maximum permanent deflection among the various fuel baskets analyzed inside the HI-STORM FW Version E for high heat loads. The temperature zones for the MPC-37 CBS fuel basket are shown in Figure 3.4.76. The temperature zones and the stress plots in the active fuel region for all other fuel baskets are documented in
[3.4.30]. The primary stresses in all the fuel baskets are less than 90% of the true ultimate strength of Metamic-HT.
To meet the requirements stated above, the newly added HI-STORM FW Version E1 tipover analyses in [3.4.34] demonstrate that (i) the maximum permanent deflection in the fuel basket meets the specified limit in Table 2.2.11 (see discussion in preceding subparagraphs, specifically 3.4.4.1.4a through 3.4.4.1.4d) and (ii) the primary stresses in the fuel basket panels are below 90% of the true ultimate strength of the Metamic-HT material. Figure 3.4.75 shows the stress levels in the active fuel region for the governing fuel basket (i.e., MPC-37CBS) inside the HI-STORM FW Version E1. The MPC-37CBS fuel basket is the governing basket as it has the least safety factor (per Table 3.4.27) for the maximum permanent deflection among the various fuel baskets analyzed inside the HI-STORM FW Version E1. The stress plots in the active fuel region for all other fuel baskets are documented in [3.4.34]. The primary stresses in all the fuel baskets are less than 90% of the true ultimate strength of Metamic-HT.
3.4.4.1.5 Load Case 5: Design, Short-Term Normal and Off-Normal MPC Internal Pressure The MPC Enclosure Vessel, which is designed to meet the stress intensity limits of ASME Subsection NB [3.4.4], is analyzed for a bounding normal (design, long-term and short-term) internal pressure (Table 2.2.1) of 120 psig using the ANSYS finite element code [3.4.1]. Except for the applied loads and the boundary conditions, the finite element model of the MPC Enclosure Vessel used for this load case is identical to the model described in Subsections 3.1.3.2 and 3.4.3.2 for the MPC lifting analysis.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-161 Table 3.4.28 PERMANENT LATERAL DEFLECTION OF FUEL BASKET PANELS DUE TO NON-MECHANISTIC TIPOVER OF HI-S Fuel Basket Type Max. Calculated Deflection (in)
Allowable Limit (in)
Safety Factor MPC-37 0.0350 0.045 1.28 MPC-89 0.007 0.030 4.28 MPC-89 CBS 0.015 0.030 2.00 MPC-37/37P CBS 0.0359 0.045 1.25 Maximum permanent deflection is calculated following the steps outlined in Table 3.4.23.
Equal to 0.005 times the cell inner dimension per Subsection 2.2.8 and Table 2.2.11. Cell inner dimension obtained from drawing package in Section 1.5.
Tipover analysis performed based on MPC-37 CBS basket geometry. Results are also bounding for MPC-37P CBS basket per discussion in subparagraph 3.4.4.1.4d.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-314 Figure 3.4.76: Temperature Zones for MPC-37 CBS (high heat load) inside HI-STORM FW Version E a)
Stresses in the 380oC region (90% of true ultimate strength: 10.24ksi)
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-315 b)
Stresses in the 365oC region (90% of true ultimate strength: 10.82ksi) c)
Stresses in the 325oC region (90% of true ultimate strength: 13.08ksi)
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 3-316 d)
Stresses in the 300oC region (90% of true ultimate strength: 14.75ksi) e)
Stresses in the 250oC region (90% of true ultimate strength: 16.5ksi)
Figure 3.4.77: Effective Stress Distribution in the Fuel Basket Panels in the Active Fuel Region (for MPC-37 CBS (high heat load) inside HI-STORM FW Version E) due to Tipover Event
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 11C 4-45 The FLUENT thermal model provides the 3-D temperature field in the HI-STORM FW system from which the changes in the above gaps are directly computed. Table 4.4.6 provides the initial minimum gaps and their corresponding value during long-term storage conditions. Significant margins against radial and axial expansion of MPC and axial expansion of basket are available in the design. The potential small basket-to-shell interference in the radial direction due to DTE in the basket, shims, and shell is acceptable as discussed in Paragraph 3.1.1(i) and Subparagraph 3.1.2.2(a).
4.4.7 Evaluation of System Performance for Normal Conditions of Storage The HI-STORM FW System thermal analysis is based on a detailed 3-D heat transfer model that conservatively accounts for all modes of heat transfer in the MPC and overpack. The thermal model incorporates conservative assumptions that render the results for long-term storage to be conservative.
Temperature distribution results obtained from this thermal model show that the maximum fuel cladding temperature limits are met with adequate margins. Expected margins during normal storage will be much greater due to the conservative assumptions incorporated in the analysis. As justified next the long-term impact of elevated temperatures reached in the HI-STORM FW system is minimal. The maximum MPC basket temperatures are below the recommended limits for susceptibility to stress, corrosion and creep-induced degradation. A complete evaluation of all material failure modes and causative mechanisms has been performed in Chapter 8 which shows that all selected materials for use in the HI-STORM FW system will render their intended function for the service life of the system. Furthermore, stresses induced due to the associated temperature gradients are modestly low (See Structural Evaluation Chapter 3).
4.4.8 Evaluation of Candidate Heat Load Pattern
[
PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390
]