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HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10JK 2-12 gradient loads are generally small; therefore, the Off-Normal Event does not generally provide a governing load combination.

Table 2.2.9 provides a reference set of parameters for the ISFSI pad and its foundation that are used solely as input to the non-mechanistic tipover analysis. Analyses in Chapter 3 show that this reference pad design does not violate the design criterion applicable to the non-mechanistic tip-over of the HI-STORM FW storage system. The pad design may be customized to meet the requirements of a particular site, without performing a site-specific tipover analysis, provided that all ISFSI pad strength properties are less than or equal to the values in Table 2.2.9. If any of the values in Table 2.2.9 are exceeded, then a site-specific tipover analysis must be performed using the methodology described in Subsection 3.4.4 to demonstrate that the acceptance criteria in paragraph 2.2.3.b are satisfied.

Applicable sections of industry codes such as ACI 318-05, Building Code Requirements for Structural Concrete; ACI 360R-92, Design of Slabs on Grade; ACI 302.1R, Guide for Concrete Floor and Slab Construction; and ACI 224R-90, Control of Cracking in Concrete Structures may be used in the design, structural evaluation, and construction of the concrete pad. However, load combinations in ACI 318-05 are not applicable to the ISFSI pad structural evaluation, and are replaced by the load combinations stated in subparagraph 2.0.4.2.b.

Holtec Letter 5018114 Attachment 3 1 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10JK 2-93 The ASME Code service limits are used in the structural analyses for definition of allowable stresses and allowable stress intensities, as applicable. Allowable stresses and stress intensities for structural analyses are tabulated in Chapter 3. These service limits are matched with normal, off-normal, and accident condition loads combinations in the following subsections.

The MPC confinement boundary is required to meet Section III, Class 1, Subsection NB stress intensity limits. Table 2.2.10 lists the stress intensity limits for Design and Service Levels A, B, and D for Class 1 structures extracted from the ASME Code. Table 2.2.12 lists allowable stress limits for the steel structure of the HI-STORM FW overpack and HI-TRAC VW transfer cask which are analyzed to meet the stress limits of Subsection NF, Class 3 for loadings defined as service levels A, B, and D are applicable.

2.2.6 Loads Subsections 2.2.1, 2.2.2, and 2.2.3 describe the design criteria for normal, off-normal, and accident conditions, respectively. The loads are listed in Tables 2.2.7 and 2.2.13, along with the applicable acceptance criteria.

2.2.7 Design Basis Loads Where appropriate, for each loading type, a bounding value is selected in this FSAR to impute an additional margin for the associated loading events. Such bounding loads are referred to as Design Basis Loads (DBL) in this FSAR. For example, the Design Basis External Pressure on the MPC, set down in Table 2.2.1, is a DBL, as it grossly exceeds any credible external pressure that may be postulated for an ISFSI site.

2.2.8 Allowable Limits The stress intensity limits for the MPC confinement boundary for the design condition and the service conditions are provided in Table 2.2.10. The MPC confinement boundary stress intensity limits are obtained from ASME Code,Section III, Subsection NB. The displacement limit for the MPC fuel basket is expressed as a dimensionless parameter defined as [2.2.11]

w

=

where is defined as the maximum permanent deflectiontotal deflection sustained by the basket panels under the loading event and w is the nominal inside (width) dimension of the storage cell.

The limiting value of is provided in Table 2.2.11, and it is also used conservatively to inform the criticality analysis model for the MPC fuel baskets, as described in Subsection 6.3.1. In addition to the deflection based criterion, the most limiting fuel basket configuration shall be further evaluated 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-Holtec Letter 5018114 Attachment 3 2 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10JK 2-94 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 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.

Holtec Letter 5018114 Attachment 3 3 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10JK 2-95 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 Letter 5018114 Attachment 3 4 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10JK 2-115 Table 2.2.15 VALUES FOR METAMIC-HT FUEL BASKETS Fuel Basket Type (Note 1)

Fuel Assembly Weight (W), lbf (Note 2)

Fuel Assembly Length (b), in (Note 2)

Fuel Weight per Unit Length (w),

lbf/in Cell ID (l), in (Note 3)

Nominal Panel Thickness (t), in (Note 3)

=

(Note 4)

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 Letter 5018114 Attachment 3 5 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10JK 2-116 Figure 2.2.1: BENDING BEHAVIOR IN METAMIC-HT FUEL BASKET DURING TIPOVER EVENT Holtec Letter 5018114 Attachment 3 6 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Revision 10JK 2-130

[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 2 (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 Letter 5018114 Attachment 3 7 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-103

1 1

2 1

A sin Mgr

=

d

)

( d 2

I

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

)

cos (1

I Mgr 2

=

)

t(

f 2

B 1

A

where, from Figure 3.4.8,

r 2

d cos

=

1-f 2

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 45

.1 =

)

t(

B 1

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.

(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 described in Subsections 3.1.3.1 and 3.1.3.2, respectively. The tipover analysis for MPC-44 is Holtec Letter 5018114 Attachment 3 8 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-105 As shown in Figure 3.4.15 and [3.4.31], the fuel basket does not experience significant plastic deformation in the active fuel region to exceed the acceptable limits; plastic deformation is essentially limited locally in cells near the top of the basket beyond the active fuel region for 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 linearized stress results. Since the membrane stress is less than the yield strength of the material at Holtec Letter 5018114 Attachment 3 9 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-107

Case 1: HI-STORM FW loaded with MPC 37 fuel basket, without corner welds, all basket panels have matching tabs and notches for interlocking perpendicular panels at the basket corners.

Case 2: HI-STORM FW loaded with MPC 37 fuel basket, without corner welds, basket panels are made with straight edges so a flat contact interface is formed between any two perpendicular panels meeting at the basket corner.

As shown in the tipover analysis [3.4.11], the standard fuel basket does not experience significant plastic deformation in the active fuel region to exceed the acceptable limits. The maximum panel displacement due to the tip-over event is located beyond the active fuel region for both MPC-37 and MPC-89 baskets (tipover of MPC-89 is not analyzed here but the results are bounded by MPC-37),

which is considered to be acceptable from the perspectives of shielding and criticality. Note that the basket corner welds are not considered in the tip-over analysis for conservatism. The maximum permanent deflections of the heaviest loaded fuel basket panel for both analyzed cases are reported in Table 3.4.21. In addition, 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. The fuel baskets in both Case 1 and Case 2 corner configuration are considered to be structurally safe as they can continue to maintain 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 (9.0%, see Figures 3.4.16D & 3.4.16E) 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 3.4.17D and 3.4.17E. 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 small plastic 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-STORM FW lid concrete, are shown to be 60.91 gs for Case 1 and 62.82 gs for Case 2 in the vertical direction (see Figures 3.4.19D & 3.4.19E) and 17.80 gs for Case 1 and 17.75 gs for 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.

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 3.4.20 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.

Holtec Letter 5018114 Attachment 3 10 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-108 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 Holtec Letter 5018114 Attachment 3 11 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-109

]

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:.

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.

[

PROPRIETARY INFORMATION WITHHELD PER 10CFR2.390

]

iii.

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

iv.

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

v.

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 Basket Design The tipover analysis for MPC-44 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 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, Holtec Letter 5018114 Attachment 3 12 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-110 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 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.

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 CBS remain attached to the basket maintaining their physical integrity. The stresses in the basket shims are mainly below the yield strength with only limited permanent deformation, as shown in Figure 3.4.46B.

iii.

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

iv.

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

v.

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 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 basket panels are thicker than that of MPC-37 CBS basket per licensing drawings in Section 1.5.

b.

MPC-37P basket cell width is smaller than that of MPC-37 CBS basket per licensing drawings in Section 1.5.

c.

Weight of MPC-37P fuel assemblies is conservatively bounded by MPC-37 fuel assemblies per Table 2.1.1.

d.

Temperature distribution of MPC-37P basket panels is bounded by MPC-37 CBS basket panels per thermal analyses supporting Chapter 4.

Holtec Letter 5018114 Attachment 3 13 of 23

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-111 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 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 basket.

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.

The only load applied to the finite element model for this load case is the bounding MPC design internal pressure for normal conditions (Table 2.2.1). All internal surfaces of the MPC storage cavity are subjected to the design pressure. The center node on the top surface of the MPC upper lid is fixed against translation in all directions. Symmetric boundary conditions are applied to the two vertical symmetry planes. This set of boundary conditions allows the MPC Enclosure Vessel to deform freely under the applied pressure load. Figure 3.4.31 graphically depicts the applied pressure load and the boundary conditions for Load Case 5.

The stress intensity distribution in the MPC Enclosure Vessel under design internal pressure is shown in Figure 3.4.23. Figures 3.4.32 and 3.4.33 plot the thru-thickness variation of the stress intensity at the baseplate center and at the baseplate-to-shell juncture, respectively. The maximum primary stress intensities in the MPC Enclosure Vessel are compared with the applicable stress intensity limits from Subsection NB of the ASME Code (Fig. NB-3221-1). The allowable stress intensities are obtained at design temperature limits in Table 2.2.3 (600F for the shell and lid, 400F for the baseplate, and 600F at the baseplate-to-shell juncture, conservatively). The maximum calculated stress intensities in the MPC Enclosure Vessel, and their corresponding allowable limits, are summarized in Table 3.4.7 for Load Case 5.

Similar evaluations are performed for the MPC Enclosure Vessel under short-term normal (Level A) and off-normal (Level B) conditions. The applied loads are bounding internal pressure (120 psig)

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HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL REPORT HI-2114830 Proposed Rev. 10K9 3-262

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Stresses in the inner core region (335oC) (90% of true ultimate strength: 12.41ksi)