ML24100A032

Attachment 4: HI-STORM FW FSAR Proposed Revision 10L, Changed Pages

ML24100A032
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Site:	07201032
Issue date:	04/08/2024
From:	Holtec
To:	Office of Nuclear Material Safety and Safeguards
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ML24100A027	List: ML24100A028 ML24100A030 ML24100A032 ML24100A038
References
5018117, CAC 001028, EPID L-2021-LLA-0053
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Text

1014 are also applicable to the MPC in the HI-STORM FW System, as documented in Table 2.2.14.

The stress limits of ASME Section III Subsection NF [2.0.3] are applied to the HI-STORM FW and HI-TRAC VW structural parts where the applicable loading is designated as a code service condition.

The fuel basket, made of Metamic-HT, is subject to the requirements in Chapter 1, Section 1.2.1.4 and is designed to a specific (lateral) deformation limit of its walls under accident conditions of loading (credible and non-mechanistic) (see Table 2.2.11). The basis for the permanent lateral deflection limit in the active fuel region, , is provided in [2.2.11]. The portions of the fuel basket outside of the active fuel region are not subject to the deflection limit since they do not affect the reactivity control function of the Metamic-HT fuel basket. The height and relative position of the active fuel region with respect to the fuel basket are dependent on the fuel assemblies being stored in the MPC, as the MPC height can be varied to accommodate different fuel types (see Table 3.2.1).

ACI 318 is the reference code for the plain concrete in the HI-STORM FW overpack. ACI 318.1-85(05) is the applicable code utilized to determine the allowable compressive strength of the plain concrete credited in strength analysis.

Each structure, system and component (SSC) of the HI-STORM FW System that is identified as important-to-safety is shown on the licensing drawings.

Tables 1.2.6 and 1.2.7 provide the information on the applicable Codes and Standards for material procurement, design, fabrication and inspection of the components of the HI-STORM FW System. In particular, the ASME Code is relied on to define allowable stresses for structural analyses of Code materials.

2.2.5 Service Limits

In the ASME Code, plant and system operating conditions are commonly referred to as normal, upset, emergency, and faulted. Consistent with the terminology in NRC documents, this FSAR utilizes the terms normal, off-normal, and accident conditions.

The ASME Code defines four service conditions in addition to the Design Limits for nuclear components. They are referred to as Level A, Level B, Level C, and Level D service limits, respectively. Their definitions are provided in Paragraph NCA-2142.4 of the ASME Code. The four levels are used in this FSAR as follows:

i. Level A Service Limits are used to establish allowables for normal condition load combinations.

ii. Level B Service Limits are used to establish allowables for off-normal conditions.

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10KL 2-92

addition to the deflection based criterion, supplemental stress analyses the most limiting fuel basket configuration shall be further evaluatedperformed to confirm that the maximum primary membrane plus bending stress in the fuel basket panels, within the active fuel region, is below 90% of the ultimate strength of Metamic-HT material, on a true stress basis, at the applicable temperature. The method used to determine the limiting basket configuration is described below.

During a tipover accident, the horizontal basket panels (i.e., parallel to ground) act like a continuous row of clamped-clamped beams, as the unsupported span lengths between vertical panels resist the amplified weight of the stored fuel assemblies. Figure 2.2.1 depicts this general panel behavior. Consequently, the classical solution for a clamped-clamped beam under a concentrated load at midspan is used below to develop a numerical parameter to identify the limiting fuel basket configuration. From [2.2.12], the bending stress at the ends of a clamped-clamped beam due a concentrated load at its midspan is:

where is the concentrated load (i.e., fuel assembly weight), is the length of the beam (i.e.,

inside dimension of storage cell), is the width of the beam section, and is the height of the beam section (i.e., thickness of fuel basket panel). Next, let equal / representing the load per unit width of the beam section (i.e., fuel assembly weight per unit length). Then, the equation becomes:

The above equation shows that the bending stress in the fuel basket panel, which acts like a beam strip, is proportional to / . Therefore, a new parameter, , is defined as:

which can be readily used to identify the limiting basket configuration for further stress evaluation. Although the above parameter is derived from the solution for the bending stress at the ends of a clamped beam, the stress at the center of the beam is also proportional to .

Therefore, is a valid measure of the primary bending stress in the fuel basket panels irrespective of the location along the beam length. Table 2.2.15 summarizes the values for all Metamic-HT fuel baskets included in this SAR.

From Table 2.2.15, the PWR fuel baskets are more limiting than the BWR fuel baskets due to their larger storage cell openings and heavier fuel assemblies. The overall limiting design is the MPC-32ML, which is a friction stir welded (FSW) fuel basket. Among the CBS style baskets, the MPC-37 CBS is most limiting. Accordingly, these two basket types (MPC-32ML and MPC-37 CBS) are explicitly analyzed in Chapter 3 to show conclusively that the primary membrane HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10KL 2-94

plus bending stress in the Metamic-HT basket panels is less than 90% of the true ultimate strength of the material. The primary bending stresses in the other fuel basket types are bounded by the results for the MPC-32ML and MPC-37 CBS based on the data in Table 2.2.15.

Since the true ultimate strength of Metamic-HT is also influenced by temperature, additional consideration is given to the fuel basket temperature results in Chapter 4. In particular, Section 4.4 concludes that fuel storage in the MPC-37 is more limiting than its BWR counterpart (i.e.,

MPC-89). Furthermore, Table 4.4.3 shows that the maximum computed fuel basket temperature is associated with the MPC-37, and the temperature results for CBS variants are essentially unchanged as compared to the corresponding friction stir welded basket per paragraph 4.4.1.12.

Thus, the thermal results also point to the PWR baskets as more limiting, and they corroborate the selection of the MPC-32ML and MPC-37 CBS as the two most limiting fuel basket configurations from a stress perspective.

For new fuel basket designs introduced in this SAR, via either a future license amendment or the 72.48 process, explicit demonstration that primary stresses in the fuel basket are below 90% of true ultimate strength is not required unless:

a) the computed value of for the new basket design is greater than the maximum value in Table 2.2.15 for the same type of construction (i.e., FSW or CBS), or;

b) the maximum computed temperature of the new basket design is greater than the maximum value for the MPC-37 reported in Table 4.4.3.

For clarity, if the new design is a CBS type basket, then should be compared against the maximum value for the MPC-37 CBS in Table 2.2.15. Conversely, if the new design is a FSW basket, then should be compared against the maximum value for the MPC -32ML in Table 2.2.15. Regardless of the value of , all Metamic-HT fuel baskets must be evaluated to demonstrate compliance with the permanent deflection limit in Table 2.2.11. If further stress evaluation is required for a particular fuel basket, based on its computed value or maximum temperature, then the stress analysis shall be performed for the storage overpack that caused the maximum permanent deflection of fuel basket panels during the non-mechanistic tipover event.

Finally, the steel structure of the overpack and the HI-TRAC VW must meet the stress limits of Subsection NF of ASME Code,Section III for the applicable service conditions.

The following definitions of terms apply to the tables on stress intensity limits; these definitions are the same as those used throughout the ASME Code:

Sm: Value of Design Stress Intensity listed in ASME Code Section II, Part D, Tables 2A, 2B and 4

Sy: Minimum yield strength at temperature

Su: Minimum ultimate strength at temperature HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10KL 2-95

Table 2.2.15

VALUES FOR METAMIC-HT FUEL BASKETS Fuel Basket Fuel Assembly Fuel Assembly Fuel Weight per Cell ID (l), in Nominal Panel =

Type Weight (W), lbf Length (b), in Unit Length (w), (Note 3) Thickness (t), in (Note 4)

(Note 1) (Note 2) (Note 2) lbf/in (Note 3)

MPC-32ML 2,200 196.1 10.81 9.57 0.59 308 MPC-37 CBS 1,750 167.2 10.47 8.96 0.59 269 MPC-37 1,750 167.2 10.47 8.96 0.59 269 MPC-44 CBS 1,150 160.0 7.19 8.10 0.51 224 MPC-89 CBS 750 176.5 4.25 6.01 0.40 160 MPC-89 750 176.5 4.25 6.01 0.40 160 MPC-37P CBS 1,510 150.0 10.07 8.80 0.79 142 Notes:

1) CBS designates fuel baskets that utilize continuous basket shims; all other basket types are assembled using friction-stir welding (FSW) process.

2) Obtained from Tables 2.1.1a through 2.1.1d; includes non-fuel hardware (NFH); DFC/DFI not included except for MPC-32ML.

3) Per licensing drawings in Section 1.5.

4) See Subsection 2.2.8 for more information.

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10KL 2-116

Figure 2.2.1: BENDING BEHAVIOR IN METAMIC-HT FUEL BASKET DURING TIPOVER EVENT

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10KL 2-117

[2.2.7] Regulatory Guide 1.76, Design Basis Tornado for Nuclear Power Plants, United States Nuclear Regulatory Commission, April 1974.

[2.2.8] ANSI/ANS 57.9-1992, "Design Criteria for an Independent Spent Fuel Storage Installation (Dry Type)", American Nuclear Society, LaGrange Park, IL, May 1992.

[2.2.9] NUREG-0800, Standard Review Plan, United States Nuclear Regulatory Commission, Washington, DC, April 1996

[2.2.10] ASME Boiler & Pressure Vessel Code,Section III, Subsection NB. Class 1 Components, American Society of Mechanical Engineers, New York, NY, 2007

[2.2.11] Holtec Proprietary Position Paper DS-331, Structural Acceptance Criteria for the Metamic-HT Fuel Basket, Revision 42 (USNRC Docket No. 71-9325).

[2.2.12] Young, W., Roarks Formulas for Stress & Strain, McGraw-Hill International, 6th Edition.

[2.3.1] ISG-2, Fuel Retrievability, Revision 2, USNRC, Washington DC

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10KL 2-131

an inert gas (helium) at a specified mass. The vent and drain ports are covered by a cover plate and welded before the closure ring is installed. The closure ring is a circular annular plate edge-welded to the MPC lid and shell. The two closure members are interconnected by welding around the inner diameter of the ring. Lift points for the MPC are provided on the MPC lid.

• The MPC fuel baskets consist of an array of interconnecting plates. The number of storage cells formed by this interconnection process varies depending on the type of fuel being stored. Basket configurations designed for both PWR and BWR fuel are explained in detail in Section 1.2. All baskets are designed to fit into the same MPC shell.

• The MPC shell is separated from the basket and its lateral supports (basket shims) by a small, calibrated gap designed to minimize, if not completely eliminate, prevent significant thermal stressing associated with the thermal expansion mismatches between the fuel basket, the basket support structure, and the MPC shell. Refer to discussion on DTE earlier in this subsection.

The MPC fuel basket maintains the spent nuclear fuel in a subcritical arrangement. Its safe operation is assured by maintaining the physical configuration of the storage cell cavities intact in the aftermath of a non-mechanistic tipover event. This requirement is satisfied if the MPC fuel basket plates undergo a minimal deflection (see Table 2.2.11). The fuel basket strains are shown in Subsection 3.4.4.1.4 to remain largely elastic with only localized areas of plastic strain. Moreover, from the stimulation results it is demonstrated that the cross section of the storage cell, throughout the active fuel length, remains essentially unchanged. Therefore, there is no impairment in the recoverability or retrievability of the fuel and the subcriticality of the stored fuel is unchallenged.

[

PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390

]

In normal operating condition, these shims are not subject to any significant loadings. The only condition in which this shim configuration experiences significant loads is the non-mechanistic tipover event when the shim extension plates may be subject to cantilever loads. This loading, which bounds all other events including seismic loads, is considered in the tipover analysis presented in Subsection 3.4.4.1.4b.

Similarly, MPC-44 CBS and MPC-37P CBS are evaluated for non-mechanistic tipover in Subsections 3.4.4.1.4c and 3.4.4.1.4d.

The MPC Confinement Boundary contains no valves or other pressure relief devices. In addition, the analyses presented in Subsections 3.4.3, 3.4.4.1.5, and 3.4.4.1.6 show that the MPC Enclosure Vessel meets the stress intensity criteria of the ASME Code,Section III, Subsection NB for all service conditions. Therefore, the demonstration that the MPC Enclosure Vessel meets Subsection NB stress limits ensures that there will be no discernible release of radioactive materials from the MPC.

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10L9 3-5

• Length: inch

3.1.3.1 HI-STORM FW Overpack

The physical geometry and materials of construction of the HI-STORM FW overpack are provided in Sections 1.1 and 1.2 and the drawings in Section 1.5. The finite element simulation of the overpack consists of two types of models, one for the overpack body and the other for the top lid.

Because the loaded overpack is virtually identical in weight and height for the standard, Version XL, domed and Version E with concrete densities up to 200 pcf , the analyses that do not require a detailed simulation of the lid apply to all four configurations. Loading events that require a detailed characterization of the lids response such as lid lifting and tornado missile impact on the HI-STORM FW lid are analyzed for each lid type separately ([3.4.13] and [3.4.15]). For overpack body with high density concrete (250 pcf), only the weight is different when compared to the standard overpack model.

The models are initially developed using the finite element code ANSYS ([3.4.1] and [3.4.25]), and then, depending on the load case, numerical simulations are performed either in ANSYS or in LS-DYNA [3.1.8]. For example, the handling loads (Load Case 9) and the snow load (Load Case 10) are simulated in ANSYS, and the non-mechanistic tipover event (Load Case 4) is simulated in LS-DYNA. For the non-mechanistic tipover analysis, three distinct finite element models are developed with HI-STORM FW overpack carrying the maximum length MPC-37 (see Figure 3.4.10A) and the maximum length MPC-89 (see Figure 3.4.10B), as well as the MPC-32ML and the MPC-44 CBS.

The overpack FE model for the MPC-32ML is the same as that for the MPC-37. This conservatively maximizes the weight and the angular velocity of the overpack for the non-mechanistic tipover analysis. The enclosure vessels for the MPC-44 CBS and the MPC-37P CBS are the same as that for the MPC-37.

The key attributes of the HI-STORM FW overpack models (implemented in ANSYS) are:

i. The finite element discretization of the overpack is sufficiently detailed to accurately articulate the primary membrane and bending stresses as well as the secondary stresses at locations of gross structural discontinuity. The finite element layouts of the HI-STORM FW overpack body and the top lid are pictorially illustrated in Figures 3.4.3A/B and 3.4.5A-D, respectively. The overpack model consists of over 70,000 nodes and 50,000 elements, which exceed the number of nodes and elements in the HI-STORM 100 tipover model utilized in

[3.1.4]. Table 3.1.11 summarizes the key input data that is used to create the finite element models of the HI-STORM FW overpack body and top lid.

ii. The overpack baseplate, anchor blocks, and the lid studs are modeled with SOLID45 elements. The overpack inner and outer shells, bottom vent shells, and the lifting ribs are modeled with SHELL63 elements. A combination of SOLID45, SHELL63, and SOLSH190 elements is used to model the steel components in the HI -STORM FW standard lid. A combination of SOLID185 and SOLSH190 elements is used to model the steel components in the HI-STORM FW Version XL lid, HI-STORM FW domed lid, and the HI-STORM FW

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10L9 3-22

3.1.3.2 Multi-Purpose Canister (MPC)

The two constituent parts of the MPC, namely (i) the Enclosure Vessel and (ii) the Fuel Basket, are modeled separately. The model for the Enclosure Vessel is focused to quantify its stress and strain field under the various loading conditions. The model for the Fuel Basket is focused on characterizing its strain and displacement behavior during a non-mechanistic tipover event. For the non-mechanistic tipover analysis, three distinct finite element models are created: one for the maximum length MPC-37, one for the maximum length MPC-89, and one for the MPC-32ML and one for the MPC-44 CBS. The finite element models for the MPC-37 and MPC-89 enclosure vessels are shown in Figures 3.4.11A and 3.4.11B, respectively. Note that the MPC-32ML enclosure vessel, carrying PWR fuel type, is identical to the MPC-37 except for the length. The finite element models for the fuel baskets, the fuel assemblies and the basket shims, for all three basket types are shown in Figures 3.4.12, 3.4.13 and 3.4.14, respectively. The finite element model for the fuel basket with the fuel assemblies and the basket shims of MPC-44 CBS are described in [3.4.31].

The key attributes of the MPC finite element models (implemented in ANSYS) are:

i. The finite element layout of the Enclosure Vessel is pictorially illustrated in Figure 3.4.1.

The finite element discretization of the Enclosure Vessel is sufficiently detailed to accurately articulate the primary membrane and bending stresses as well as the secondary stresses at locations of gross structural discontinuity, particularly at the MPC shell to baseplate juncture.

This has been confirmed by comparing the ANSYS stress results with the analytical solution provided in [3.4.16] (specifically Cases 4a and 4b of Table 31) for the discontinuity stress at the junction between a cylindrical shell and a flat circular plate under internal pressure (100 psig). The two solutions agree within 3% indicating that the finite element mesh for the Enclosure Vessel is adequately sized. Table 3.1.14 summarizes the key input data that is used to create the finite element model of the Enclosure Vessel.

ii. The Enclosure Vessel shell, baseplate, and upper and lower lids are meshed using SOLID185 elements. The MPC lid-to-shell weld and the reinforcing fillet weld at the shell-to-baseplate juncture are also explicitly modeled using SOLID185 elements (see Figure 3.4.1).

iii. Consistent with the drawings in Section 1.5, the MPC lid is modeled as two separate plates, which are joined together along their perimeter edge. The upper lid is conservatively modeled as 4.5 thick, which is less than the minimum thickness specified on the licensing drawing (see Section 1.5). Surface-to-surface contact is defined over the interior interface between the two lid plates using CONTA173 and TARGE170 contact elements.

iv. The materials used to represent the Enclosure Vessel are assumed to be isotropic and are assigned linear elastic material properties based on the Alloy X material data provided in Section 3.3. The Youngs modulus value varies throughout the model based on the applied temperature distribution, which is shown in Figure 3.4.27 and conservatively bounds the temperature distribution for the maximum length MPC as determined by the thermal analyses in Chapter 4 for short-term normal operations.

v. The fuel basket models (Figures 3.4.12A, 3.4.12B and 3.4.12C), which are implemented in

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10L9 3-24

3.2 WEIGHTS AND CENTERS OF GRAVITY

As stated in Chapter 1, while the diameters of the MPC, HI-STORM FW, and HI-TRAC VW are fixed, their height is dependent on the length of the fuel assembly. The MPC cavity height (which determines the external height of the MPC) is set equal to the nominal fuel length (along with control components, if any) plus , where is a small adder provided to account for irradiation and thermal growth of the fuel in the reactor. Table 3.2.1 provides the height of the internal cavities and bottom-to-top external dimension of all system components. Table 3.2.2 provides the parameters that affect the weight of cask components and their range of values assumed in this FSAR.

The cavity heights of the HI-STORM FW overpack and the HI-TRAC VW transfer cask are set greater than the MPC height by fixed amounts to account for differential thermal expansion and manufacturing tolerances. Table 3.2.1 provides the height data on HI-STORM FW, HI-TRAC VW, and the MPC as the adder to the MPC cavity length.

Table 3.2.5 provides the reference weight of the HI-STORM FW overpack for storing MPC-37 and MPC-89 containing reference PWR and BWR fuel, respectively. Conservatively, the HI-STORM FW overpack storing MPC-32ML, MPC-37P CBS and MPC-44 CBS carrying PWR fuel, uses the samebounding or maximum PWR fuel reference weights listed in Tables 3.2.5 and 2.1.1 for structural analysis purposes. The weight of the HI-STORM FW overpack body is provided for multiple concrete densities and for two discrete heights for PWR and BWR fuel for both standard, Version XL, and Version E configurations. The weight at any other density and any other height can be obtained by linear interpolation. Similarly, the weight of the HI-STORM FW standard lid, Domed lid, and Version E lid is provided for two discrete values of concrete density. The weight corresponding to any other density can be computed by linear interpolation.

As discussed in Section 1.2, the weight of the HI-TRAC VW transfer cask is maximized for a particular site to take full advantage of the plants crane capacity within the architectural limitations of the Fuel Building. Accordingly, the thickness of the lead shield and outer diameter of the water jacket can be increased to maximize shielding. The weight of the empty HI-TRAC VW cask in Table 3.2.4 is provided for three lengths corresponding to PWR fuel. Using the data for three lengths, the transfer casks weight corresponding to any other length can be obtained by linear interpolation (or extrapolation). For MPC-89, the weight data is provided for the minimum and reference fuel lengths, as well as the reference fuel assembly with a DFC and therefore likewise the transfer casks weight corresponding to any other length can be obtained by linear interpolation (or extrapolation).

The approximate change in the empty weight of HI-TRAC VW (in kilo pounds) of a certain height, h (inch), by virtue of changing the thickness of the lead by an amount, (inch), is given by the formula:

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10L9 3-43

which can be integrated over the limits 1 = 0 to 1 = 2f (Figure 3.4.8). The final angular velocity 1 at the time instant just prior to contact with the ISFSI pad is given by the expression

where, from Figure 3.4.8,

This equation establishes the initial conditions for the final phase of the tip-over analysis; namely, the portion of the motion when the cask is decelerated by the resistive force at the ISFSI pad interface. Using the data germane to HI-STORM FW (Table 3.4.11) and the above equations, the angular velocity of impact is calculated as

rad/sec

The LS-DYNA analysis to characterize the response of the HI-STORM FW system under the non-mechanistic tipover event is focused on threetwo principal demonstrations, namely:

(i) The permanent lateral deflectiondeformation of the basket panels in the active fuel region is less than the limiting value in Table 2.2.11.

(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.

(ii)(iii) The impact between the MPC guide tubes and the MPC does not cause a thru -wall penetration of the MPC shell.

ThreeFour LS-DYNA finite element models are developed to simulate the postulated tipover event of HI-STORM FW storage cask with loaded MPC-37, MPC-44, MPC-89 and MPC-32ML with standard fuel baskets, respectively. The three LS-DYNA models are constructed according to the dimensions specified in the licensing drawings included in Section 1.5; the tallest configuration for each MPC enclosure type is considered to ensure a bounding tipover analysis. Because of geometric and loading symmetries, a half model of the loaded cask and impact target (i.e., the ISFSI pad) is considered in the analysis. The LS-DYNA models of the HI-STORM FW overpack and the MPC are

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10L9 3-103

As shown in Figure 3.4.15 and [3.4.31], tThe 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 the MPC-37, MPC-44, MPC-89 and MPC-32ML standard baskets. Nonetheless, to ensure compliance with the allowable limit in Subsection 2.2.8, the maximum permanent deflection of the most heavily loaded basket panel, at any elevation within the active fuel region, is obtained from the LS-DYNA solution and reported in Table 3.4.19 for the MPC-37, MPC-89 and MPC-32ML fuel baskets. The fuel baskets areis considered to be structurally safe since theyit can continue maintaining appropriate spacing between fuel assemblies after the tipover event. The MPC enclosure vessel experiences minor plastic deformation at the impact locations with the overpack guide tubes; the maximum local plastic strain (10.9%, see Figure 3.4.16) is well below the failure strain of the material and smaller than the plastic strain limit (i.e., at least 0.2 for stainless steel) recommended by [3.4.6] for ASME NB components. Similarly, local plastic deformation occurs in the overpack shear ring near the cask-to-pad impact location as shown in Figure 3.4.17. 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, only a negligibly small plastic strain is observed in the bolt near the impact location (see Figure 3.4.18). Therefore, the cask lid will not dislodge after the tipover event. Finally, Figures 3.4.19 and 3.4.20 present the deceleration time history results of the cask lid predicted by LS-DYNA. The peak rigid body decelerations measured for the HI-STORM FW lid concrete are shown to be 65.4 gs in vertical direction and 19.3 gs in the horizontal direction. 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 [3.1.4].

The structural integrity of the HI-STORM FW lid (standard, Version XL, domed, and Version E) cannot be ascertained from the LS-DYNA tipover analyses since some components of the lid, namely the lid outer shell and the lid gussets, are defined as rigid members in order to simplify the modeling effort and maintain proper connectivity. Therefore, separate structural analyses have been performed for the HI-STORM FW lid (standard, Version XL , domed, and Version E) using ANSYS ,

wherein a bounding peak rigid body deceleration established based on LS-DYNA tipover analysis results is statically applied to the lids. The finite element model is identical to the one used in Subsection 3.4.3 to simulate a vertical lift of the HI-STORM FW lid (Figures 3.4.5A, 3.4.5B, 3.4.5C, and 3.4.5D), except that the eight circumferential gussets are conservatively neglected (i.e.,

deleted from the finite element model for the standard lid).

The resulting stress distributions in the HI-STORM FW lids (standard, Version XL, domed, and Version E) are shown in Figures 3.4.21A through 3.4.21G Per Subsection 2.2.3, the HI-STORM FW lids should not suffer any gross loss of shielding as a result of the non-mechanistic tipover event. To satisfy this criterion, the primary membrane stresses in the lid components are compared against the material yield strength. The most heavily loaded component in the standard lid is the upper shim plate closest to the point of impact (Figure 3.4.21A). In order to determine the primary membrane stress in the upper shim plate, the stresses are linearized along a path that follows the outside vertical edge of the upper shim plate (see Figure 3.4.21A for path definition). Figure 3.4.22A shows the

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For added assurance that the structural integrity and criticality function of the fuel baskets are safely maintained following a non-mechanistic tipover event, the MPC-32ML fuel basket, which is specifically identified in Subsection 2.2.8 as a limiting fuel basket configuration, is further evaluated in [3.4.30] to show that primary stress levels in the fuel basket are below 90% of the true ultimate strength of Metamic-HT within the active fuel region. This stress compliance demonstration is performed for the MPC-32ML inside a HI-STORM FW Version E, which is the governing overpack based on a comparison of the permanent deflection results in Tables 3.4.19 and 3.4.20. Figure 3.4.47 shows the stress levels in the active fuel region of the MPC-32ML fuel basket, confirming that primary stresses are below 90% of the true ultimate strength of Metamic-HT for all temperature regions. The areas where the computed stress exceeds 90% of the true ultimate strength are very localized and few in number, and they generally coincide with local structural discontinuities (e.g.,

notch locations in the fuel basket panels). Such stresses are classified as secondary or peak stresses, and they may exceed 90% of the true ultimate strength provided they do not compromise the gross structural integrity of the fuel basket, which is demonstrated by analysis in [3.4.30].

Finally, tThe 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.

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 pad, tThe bounding target foundation properties per Table 2.2.9 are utilized.

[

PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390

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]

The complete details of the finite element model, input data and results are archived in the calculation package [3.4.11]. In summary, the results of the tipover analysis The following conclusions demonstrate that all safety criteria are satisfied for the cask system with MPC-89 CBS basket design, which means:.

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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.

i. 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.

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.

ii.iii. [

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]

iii.iv. The plastic strains in the MPC enclosure vessel remain below the allowable material plastic strain limit.

iv.v. The cask closure lid does not dislodge after the tipover event, i.e., the closure lid bolts remain in-tact.

v.vi. The structural analyses of cask closure lids are performed in [3.4.13] using bounding peak deceleration values; therefore, the lids do not suffer any gross loss of shielding.

3.4.4.1.4c Load Case 4: Non-Mechanistic Tipover of MPC-44 CBS Basket Design

The tipover analysis for MPC-44 CBS is postulated only in the HI-STORM FW Version E overpack.

The same modelling approach described in subparagraph 3.4.4.1.4a is used to construct the tipover model in LS-DYNA, except that the standard HI-STORM FW overpack is replaced by the Version E overpack, and the MPC-44 CBS replaces the MPC-37. The fully assembled tipover model for the MPC-44 inside the HI-STORM FW Version E overpack is shown in Figure 3.4.9D. The tipover analysis is performed for the MPC-44 basket design using the existing design basis tipover model in LS-DYNA where the MPC-37 standard basket and aluminum shims are replaced with a fully articulated MPC-44 basket. The finite element model of the MPC-44 CBS basket is shown in Figure 3.4.12E. The continuous basket shims are modelled using the same approach employed for the MPC-89 CBS, which is described in subparagraph 3.4.4.1.4b. Lastly, the finite element model of the ISFSI is the same as described above in subparagraph 3.4.4.1.4a. For the ISFSI pad, the bounding target foundation properties per Table 2.2.9 are utilized.

Like other basket designs, the response of the MPC-44 CBS basket during the tipover event is predominantly elastic with very localized areas of plasticity, as shown in Figure 3.4.15E.

Nonetheless, to insure compliance with the allowable limit in Subsection 2.2.8, the maximum lateral deformation of the most heavily loaded CBS basket panel, at any elevation within the active fuel region, is obtained from the LS-DYNA solution and reported in Table 3.4.19.

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 The following conclusions demonstrate that all safety criteria are satisfied for the cask system with MPC-44 CBS basket design, which means:

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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.

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.

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 analyses of cask closure lids are performed in [3.4.13] using bounding peak deceleration values; therefore, the lids do not suffer any gross loss of shielding.

3.4.4.1.4d Load Case 4: Non-Mechanistic Tipover of MPC-37P CBS Basket Design

A non-mechanistic tipover of HI-STORM FW Version E cask with MPC-37P basket inside is not explicitly analyzed because it is bounded by the tipover analysis of MPC-37 CBS basket. The reasons areThe tipover analysis of the following reasons:

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 3.4.19. In addition, since the MPC-37 CBS fuel basket is designated as the limiting CBS basket configuration in Subsection 2.2.8, it is subject to a further stress evaluation in [3.4.30] to confirm that primary stresses in the fuel basket panels, within the active fuel region, are below 90% of the true ultimate strength of Metamic-HT material for all temperature regions. Figure 3.4.48 shows the stress levels in the active fuel region of the MPC-37 CBS fuel basket, which are below the allowable primary stress limit. The stress distribution in the basket shims is plotted in Figure 3.4.46C, which shows that the stresses in the CBS are mainly below

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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.

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:

[

PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390

]

The updated LS-DYNA model with the changes described above is referred to hereinafter as the enhanced tipover model. In what follows, four specific MPC/overpack pairings are re-analyzed using the enhanced tipover model to confirm that the primary stresses in the fuel basket panels are below 90% of the true ultimate strength of Metamic-HT at the applicable temperature. The basis for selection of the overpack/MPC pairings for additional stress analysis is discussed below.

[

PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390

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]

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[

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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 3.4.48 through 3.4.51, as well as the deflection results in Tables 3.4.19 and 3.4.20, 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 3.4.22, when they are loaded inside the standard HI-STORM FW or the HI-STORM FW Version E, as permitted by the CoC.

For any future tipover analyses, it must be confirmed that (i) the maximum permanent deflection in the fuel basket meets the specified limit in Table 2.2.11 and (ii) the primary stresses in the fuel basket panels are below 90% of the true ultimate strength of the Metamic-HT material, as required by Subsection 2.2.8. This can be accomplished using either separate tipover models for determination of permanent deflections and primary stresses, consistent with the established method of evaluation, or the enhanced tipover model, as described in this subparagraph, can be used to evaluate both permanent deflections and primary stresses in the fuel basket in one comprehensive solution.

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.

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Table 3.4.22

KEY PARAMETERS FOR METAMIC-HT FUEL BASKETS Fuel Basket Fuel Assembly Fuel Assembly Fuel Weight per Cell ID (l), in Nominal Panel Value of Type Weight (W), lbf Length (b), in Unit Length (Note 3) Thickness (t), in , lbf/in2 (Note 1) (Note 2) (Note 2) (w), lbf/in (Note 3)

MPC-32ML 2,200 196.1 11.22 9.57 0.59 308 MPC-37 CBS 1,750 167.2 10.47 8.96 0.59 269 MPC-37 1,750 167.2 10.47 8.96 0.59 269 MPC-44 CBS 1,150 160.0 7.19 8.10 0.51 224 MPC-89 CBS 750 176.5 4.25 6.01 0.40 160 MPC-89 750 176.5 4.25 6.01 0.40 160 MPC-37P CBS 1,510 150.0 10.07 8.80 0.79 142 Notes:

1) CBS designates fuel baskets that utilize continuous basket shims; all other basket types are assembled using friction-stir welding (FSW) process.

2) Obtained from Tables 2.1.1a through 2.1.1d; includes non-fuel hardware (NFH); DFC/DFI not included except for MPC-32ML.

3) Per licensing drawings in Section 1.5.

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Figure 3.4.9D: LS-DYNA Tipover Model - HI STORM FW Version E Loaded with MPC-44 CBS

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Figure 3.4.12F: LS-DYNA Model - MPC-37 CBS Fuel Basket (note: the different colors represent regions with bounding temperatures of 380C, 365C, 300C and 250C, respectively)

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Figure 3.4.15A: Maximum Plastic Strain - MPC-37 Fuel Basket

Intentionally Deleted

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Figure 3.4.15B: Maximum Plastic Strain - MPC-89 Fuel Basket

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Figure 3.4.15C: Maximum Plastic Strain - MPC-32ML Fuel Basket

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Figure 3.4.15D: Maximum Plastic Strain - MPC-89 CBS Fuel Basket

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Figure 3.4.15E: Maximum Plastic Strain - MPC-44 CBS Fuel Basket

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Figure 3.4.47: Bending Behavior in Metamic-HT Fuel Basket During Tipover Event

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3. Stresses in the 260oC region (90% of true ultimate strength: 16.15ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

4. Stresses in the 200oC region (90% of true ultimate strength: 18.24ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

Figure 3.4.487: Effective Stress Distribution in the Fuel Basket Panels in the Active Fuel Region (for MPC-32ML inside HI-STORM FW Version E) due to Tipover Event

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g) Stresses in the 245oC region (90% of true ultimate strength: 16.67ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

h) Stresses in the 180oC region (90% of true ultimate strength: 19.43ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

Figure 3.4.498: Effective Stress Distribution in the Fuel Basket Panels in the Active Fuel Region (for MPC-37 CBS inside HI-STORM FW Version E) due to Tipover Event

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a) Stresses in the inner core region (365oC) (90% of true ultimate strength: 10.82ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

b) Stresses in the 350oC region (90% of true ultimate strength: 11.40ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

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c) Stresses in the 325oC region (90% of true ultimate strength: 13.08ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

d) Stresses in the 200oC region (90% of true ultimate strength: 18.24ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

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Figure 3.4.50: Effective Stress Distribution in the Fuel Basket Panels in the Active Fuel Region (for MPC-37 inside HI-STORM FW Version E) due to Tipover Event

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a) Stresses in the inner core region (365oC) (90% of true ultimate strength: 10.82ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

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b) Stresses in the middle and outer region (300oC) (90% of true ultimate strength: 14.75ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

c) Stresses in the bottom region (180oC) (90% of true ultimate strength: 19.49ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

Figure 3.4.51: Effective Stress Distribution in the Fuel Basket Panels in the Active Fuel Region (for MPC-89 CBS inside Standard HI-STORM FW) due to Tipover Event

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Figure 3.4.52A: Updated Temperature Zones for MPC-32ML Fuel Basket

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Figure 3.4.52B: Updated Temperature Zones for MPC-89 CBS Fuel Basket

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Figure 3.4.52C: Updated Temperature Zones for MPC-37 CBS Fuel Basket

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The same ISFSI concrete pad material model used for the standard HI-STORM FW tipover analysis in Subparagraph 3.4.4.1.4 is adopted for the HI-STORM FW Version UVH tipover analysis. Specifically, the concrete pad behavior is characterized using the same LS-DYNA material model (i.e., MAT_PSEUDO_TENSOR or MAT_016) as for the tipover analysis of the standard HI-STORM FW cask in Subparagraph 3.4.4.1.4. Similarly, the subgrade is also conservatively modeled as an elastic material. Note that this ISFSI pad material modeling approach was originally taken in the USNRC approved storage cask tipover and end drop LS-DYNA analyses [3.4.5] where a good correlation was obtained between the analysis results and the test results.

To assess the potential damage of the cask caused by the tipover accident, an LS-DYNA nonlinear material model with strain rate effect is used to model the responses of all HI-STORM FW Version UVH cask structural members based on the true stress-strain curves of corresponding materials.

Note that the strain rate effect for the fuel basket material, i.e., Metamic-HT, is not considered for conservatism.

Figure 3.I.3.3 depicts the finite element tipover analysis model developed for the HI-STORM FW Version UVH cask configurations with loaded MPC-37. Identical models are prepared for the HI-STORM FW Version UVH cask loaded with MPC-89 and MPC-44 CBS. Table 3.I.3.9 summarizes the maximum plastic strain results for each MPC fuel basket, along with the corresponding material failure strains. The plastic strain contours are plotted in Figures 3.I.3.4 through 3.I.3.6 for all three fuel baskets.

From the tipover solutions, It is observed from these three figures that the strains within the active fuel region are mainly elastic, and the peak strains are below the material failure strain limit. Plastic deformation occurs only in localized areas of the peripheral cells of all three baskets (MPC-37, MPC-89 and MPC-44 CBS) near the top of the basket or in the bottom mouse hole region beyond the active fuel region. The MPC-44 is the limiting basket design from a tipover perspective based on the strain contours plotted in Figures 3.I.3.4 through 3.I.3.6. This is because the visible plastic strain regions are more widespread, and the strain values are also higher for the MPC-44.

Nonetheless, all three basket types are further evaluated to determine the maximum permanent deformation of the heaviest loaded basket panel for direct comparison with the allowable limit in Table 2.2.11. The deflection results are summarized in Table 3.I.3.12.

The MPC enclosure vessel also experiences minor plastic deformation at the impact location with overpack inner shell. The maximum local plastic strain, which is reported in Table 3.I.3.9, is well below the failure strain of the material and also smaller than the conservatively established plastic strain design limit (i.e., at least 0.2 for stainless steel) recommended by [3.4.6] for ASME NB components. Local plastic deformation occurs in the overpack inner shell due to the interaction with the MPC closure lid. Similar local plastic deformation occurs in the top region of the overpack outer shell and in the overpack lid outer shell at the impact location with the ISFSI pad. The strains in the overpack (including the lid) remain below the material failure strain limit. Furthermore, the shielding capacity of overpack (including the lid) is not 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

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event, only a negligibly small plastic strain is observed in the bolt.Figure 3.I.3.3 depicts the finite-element tipover analysis model developed for the HI-STORM FW Version UVH cask configurations with loaded MPC-37. Identical models are prepared for the HI-STORM FW Version UVH cask loaded with MPC-89 and MPC-44. Table 3.I.3.9 summarizes the maximum plastic strain results, along with the corresponding material failure strains.

From Figures 3.I.3.4 to 3.I.3.6 and Table 3.I.3.9, it is observed that the strains within the active fuel region are below the material failure strain limit. Local plastic deformation essentially develops only in a couple of peripheral cells of all three baskets (MPC-37, MPC-89 and MPC-44) near the top of the basket or in the bottom mouse hole region beyond the active fuel region. All three fuel baskets are structurally safe since they can continue maintaining appropriate spacing between fuel assemblies after the tipover event. The MPC enclosure vessel also experiences minor plastic deformation at the impact location with overpack inner shell; the maximum local plastic strain is well below the failure strain of the material and also smaller than the conservatively established plastic strain design limit (i.e., at least 0.2 for stainless steel) recommended by [3.4.6]

for ASME NB components. Local plastic deformation occurs in the overpack inner shell due to the interaction with the MPC closure lid. Similar local plastic deformation occurs in the top region of the overpack outer shell and in the overpack lid outer shell at the impact location with the ISFSI pad. The strains in the overpack (including the lid) remain below the material failure strain limit.

Furthermore, the shielding capacity of overpack (including the lid) is not 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, only a negligibly small plastic strain is observed in the bolt.

The complete details of the finite element model, input data and results are archived in the calculation package [3.4.31]. In summary, the results of the tipover analyses The following conclusions demonstrate that all safety criteria are satisfied for the Version UVH cask with MPC-37, MPC-44 CBS, and MPC-89 basket designs, which means:.

i. The lateral deflection of the most heavily loaded basket panel in the active fuel region complies with the deflection criterion in Table 2.2.11.

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 discussion of results below.

i. 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.

ii.iii. The CBSshims in MPC-44 basket remain attached to the MPC-44 fuel basket it maintaining theirits physical integrity. The stresses in the basket shims are mainly below the yield strength with only limited permanent deformation, as shown in Figure 3.I.3.13.

iii.iv. The plastic strains in the MPC enclosure vessel remain below the allowable material plastic strain limit.

iv.v. The cask closure lid does not dislodge after the tipover event, i.e., the closure lid bolts remain in-tact.

v.vi. The lid or the cask body do not suffer any gross loss of shielding.

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Finally, for added assurance that the fuel baskets maintain their structural integrity after the non-mechanisitic tipover event, a supplemental stress analysis is performed for the MPC-37 stored inside the HI-STORM FW Version UVH to demonstrate compliance with primary stress limit set forth in Subsection 2.2.8. The MPC-37 fuel basket is selected because it is geometrically more limiting than the MPC-89 and MPC-44 CBS, as discussed in subparagraph 3.4.4.1.4e and further quantified in Table 3.4.22.

The stress analysis is performed in LS-DYNA using the enhanced tipover model described in subparagraph 3.4.4.1.4e. [

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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.I.3.14, as well as the deflection results in Table 3.I.3.12, 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 of the HI-STORM FW Version UVH, and thus will preserve the criticality safety of the spent fuel storage array.

For any future tipover analyses, it must be confirmed that (i) the maximum permanent deflection in the fuel basket meets the specified limit in Table 2.2.11 and (ii) the primary stresses in the fuel basket panels are below 90% of the true ultimate strength of the Metamic-HT material, as required by Subsection 2.2.8. This can be accomplished using either separate tipover models for determination of permanent deflections and primary stresses, consistent with the established method of evaluation, or the enhanced tipover model, as described in this subparagraph, can be used to evaluate both permanent deflections and primary stresses in the fuel basket in one comprehensive solution.

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Figure 3.I.3.4: Maximum Plastic Strain -MPC-37 Fuel Basket

Intentionally Deleted

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Figure 3.I.3.5: Maximum Plastic Strain -MPC-89 Fuel Basket

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Figure 3.I.3.6: Maximum Plastic Strain -MPC-44CBS Fuel Basket

Intentionally Deleted

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a) Stresses in the inner core region (365oC) (90% of true ultimate strength: 10.82ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

b) Stresses in the middle region (350oC) (90% of true ultimate strength: 11.40ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

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c) Stresses in the outer core region (325oC) (90% of true ultimate strength: 13.08ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

d) Stresses in the bottom region (200oC) (90% of true ultimate strength: 18.24ksi)

(Note: Grey colored elements indicate stresses are below 90% of true ultimate strength.)

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Figure 3.I.3.14: Effective Stress Distribution in the Fuel Basket Panels in the Active Fuel Region (for MPC-37 inside HI-STORM FW Version UVH) due to Tipover Event

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