ML17360A162

International Submittal of Responses to NRCs 2nd Round RAIs for HI-STAR 100 Amendment Number 3

ML17360A162
Person / Time
Site:	07201008
Issue date:	12/15/2017
From:	Manzione K Holtec
To:	Cuadrado J Document Control Desk, Division of Spent Fuel Management
References
5014831
Download: ML17360A162 (30)

Text

HOLTEC INTERNATIO N AL December 15, 2017 Holtec Technology Campus, One Holtec Blvd, Camden, NJ 08104 Telephone (856) 797-0900 Fax (856) 797-0909 Jose Cuadrado Project Manager - Licensing Branch Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 72-1008, Certificate of Compliance (CoC) No. 1008

Subject:

Submittal of Responses to NRC's 2 11d Round RA ls for HI-STAR I 00 Amendment Number 3 Reference(s): [I] "Second Request for Additional Information -

Amendment No. 3 to Certificate of Compliance No. I 008 for the HI-STAR 100 Cask Storage System" (Letter from Jose Cuadrado (NRC) to Kimberly Manzione (Holtec) dated November 30, 201 7)

Dear Mr. Cuadrado:

By letter dated November 30, 2017 [I], NRC staff requested additional information (RA Is) needed to complete their detailed technical review of HI-STAR 100 Amendment 3 to the Certificate of Compliance No. I 008. to this letter contains the responses to the RAls. contains the proposed FSAR changed pages. The FSAR utilizes track changes, and yellow highlighting to identify the changes specific to these RAI responses, to differentiate them from track changes used for previous RAI and RSI responses.

If you have any questions please contact me at 856-797-0900 ext. 3951.

Sincerely, Kimberly Manzione Licensing Manager, Holtec International Document ID 501483 1 Page I of2

HOLTEC INTERNATIONAL cc:

(via email)

Holtec Technology Campus, One Holtec Blvd, Camden, NJ 08104 Telephone (856) 797-0900 Fax (856) 797-0909 Mike Layton (USNRC)

John McKirgan (USNRC)

Meraj Rahimi (US RC)

Attachments:

Attachment I: Responses to Requests for Additional Information (RAls) for HI-STAR I 00 LAR 1008-3 : HI-STAR I 00 FSAR Proposed Changed pages (Proposed Rev. 4.B)

Document ID 5014831 Page 2 of2

ATTACHMENT 1 TO HOLTEC LETTER 501483*!

Second Request for Additional Information Docket No. 72-1008 Certificate of Compliance No. 1008 HI-STAR 100 Cask Storage System Amendment No. 3 By letter dated September 25, 2015, as supplemented on January 15, and April 29, 2016, Holtec International (Holtec) submitted a request to the U.S. Nuclear Regulatory Commission (NRC or staff) to amend Certificate of Compliance (CoC) No. 1008 for the HI-STAR 100 Cask Storage System.

This request for additional information (RAI) identifies additional information needed by the NRC staff in connection with its review of the amendment application. The requested information is listed by topic and/or page number in the application and associated documentation. NUREG-1536, Revision 1, "Standard Review Plan for Dry Cask Storage Systems" was used by the staff in its review of the application.

Each individual RAI section describes information needed by the staff to complete its review of the application and to determine whether the applicant has demonstrated compliance with the regulatory requirements.

4.0 Thermal Evaluation 4-1 Provide additional justifications, more specific incorporation by reference, and/or thermal analyses that demonstrate how the thermal performance of the MPC-68 canister bounds that of the MPC-32 canister when loaded in the HI-STAR 100 Cask Storage System in vertical and horizontal orientation for normal, off-normal, and accident storage conditions, and evaluate the resulting peak cladding temperature and SSCs maximum temperatures, thermal stresses, and canister cavity pressures in Chapter 4 of the application.

In its response to the first RAI, the applicant provided additional descriptions of the HI-TRAC and HI-STAR 100 dimensions, design features, and heat transfer mechanisms and states that because the thermal analyses for the HI-STORM 100 Cask Storage System (Coe No. 1004) demonstrate that the MPC-68 bounds the MPC-32 in the HI-TRAC transfer cask, then a similar result will be expected for the HI-ST AR 100 overpack and that the MPC-68 results will bound the MPC-32. However, the amendment application does not address the specific differences, if any, between the HI-TRAC and HI-STAR 100 thermal models used to calculate the maximum temperatures for the MPC-32 and MPC-68, respectively; nor does it provide sufficient description or references for how the thermal model of the HI-TRAC transfer cask (referenced from the HI-STORM 100 FSAR) adequately considers normal, off normal, and accident conditions of storage for the MPC-32 in the HI-STAR 100 Cask Storage System. During the review of Holtec's application for Amendment No. 11 to the HI-STORM 100 System (Docket No.

72-1014, ADAMS Accession No. ML16323A118), the staff raised similar questions concerning the assumption that the thermal model for the MPC-68 bounds the MPC-32, which resulted in the reduction of the MPC-32 canister decay heat. If the applicant chooses to provide additional justification or incorporation by reference to address the Enclosure Page 1 of 13

ATTACHMENT 1 TO HOLTEC LETTER 5014831 staffs request, it should ensure that the information provided is thoroughly discussed and/or properly referenced in its proposed Final Safety Analysis Revision (FSAR).

Alternatively, if the applicant chooses to provide additional thermal analyses to address the staffs request, the applicant should submit any associated input and output files with its response.

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

Holtec Response: To address the reviewer's query in the most direct manner, the steady state thermal analysis of a vertically-oriented HI-STAR 100 under the normal condition of storage containing an MPC-32 has been performed using the licensing-basis Fluent model 1. For reference purposes, the analysis for the case with HI-STAR 100 containing an MPC-68 is also tabulated below. Two columns in the table below provide the post-processed results for the ve11ically-oriented HI-STAR 100 containing an MPC-32 and an MPC-68. respectively. Results for both fission product barriers (i.e., the cladding of intact fuel and the limiting M PC confinement boundary component, which is the MPC shell) are presented.

Table 4-1.1: MPC-68 and MPC-32 Results in Vertical Orientation Component MPC-32 Vertical MPC-68 Vertical Normal Storage (Licensing Basis Heat (Licensing Basis Heat Allowable Note 2 Load= 18.5 kW)

Load = 18.5 kW) Note 1 Maximum Contents and Components Temperatures Fuel Cladding 710°F 741 °F 752°F MPC Shell 315°F 331°F 450°F Confinement Boundary Pressure Note 3 MPC Internal Pressure 46.6 psig 57.5 psig JOO psig Notes I. The temperature and MPC cavity pressure results for MPC-68 are extracted from Tables 4.4.1 I and 4.4.15 of HI-STAR JOO FSAR [I].

2. The temperature and pressure limits are extracted from Tables 2.2.3 and 2.2. I of HI-STAR 100 FSAR [I).

3. The initial helium backfill pressures used to compute the confinement boundary pressures are 36.9 psia for the MPC-32 and 43.2 psia for the MPC-68, both at a 70°F reference temperature. These conservatively bound the nominal backfill requirements from Table 2-1 in Appendix A of the proposed technical specifications.

The e results indicate that, in the ve11ical orientation, the M PC-68 case provides a higher temperature for the fuel cladding compared to MPC-32 under normal conditions of storage. Most impo11ant, all safety-significant temperatures and pressure are found to be well below their respective limits (provided in the last column of the above table).

For a horizontally-oriented HI-STAR I 00, the steady state thermal analysis results for the normal condition of tran port from the HI-STAR I 00 SAR is incorporated by reference. Two columns in the 1 These calculations were performed using the methodology described in Section 4.4 of the HI-STAR 100 FSAR.

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ATTACHMENT 1 TO HOLTEC LETTER 5014831 table below provide the results for the horizontally-oriented HI-STAR 100 containing a PWR MPC and a BWR MPC from Chapter 3 of HI-STAR I 00 SAR. Results for both fission product barriers (i.e., the cladding of intact fuel and the limiting MPC confinement boundary component, which is the MPC shell) are presented.

Table 4-1.2: MPC-68 and MPC-32 Results in Horizontal Orientation Component MPC-32 Horizontal MPC-68 Horizontal Normal Storage (Licensing Basis Heat (Licensing Basis Heat Allowable Note 3 Load= 20 kW) Note 1 Load= 18.5 kW) "

0 ** 2 Maximum Contents and Components Temperatures Fuel Cladding 701 °F 713°F 752°F MPC Shell 315°F 306°F 450°F Confinement Boundary Pressure Note 4 MPC Internal Pressure 89.3 psig 85.8 psig 100 psig Notes I. The temperature and MPC cavity pressure results for MPC-32 are incorporated by reference from Tables 3.4.10 and 3.4.15 of HI-STAR I 00 SAR [2].

2. The temperature and MPC cavity pressure results for MPC-68 are incorporated by reference from Tables 3.4.11 and 3.4.15 of HI-STAR I 00 SAR [2].

3. The temperature and pressure limits are extracted from Tables 2.2.3 and 2.2. I of HI-STAR 100 FSAR [I].

4. The initial helium backfill pressure used to compute the confinement boundary pressures is 42.8 psig at a 70°F reference temperature, the maximum backfill level from Table 2-1 in Appendix A of the proposed technical specifications.

These results indicate that, in the horizontal orientation, the MPC-68 case provides a higher temperature for the fuel cladding compared to MPC-32. Most important, all safety-significant temperatures and pressure are found to be well below their respective limits (provided in the last column of the above table).

Sub-Section 4.4.2.1 of the FSAR will be revised to provide the above clarifications. Since MPC-68 bounds MPC-32, safety conclusions made for off-normal and accident conditions in Chapter 11 of HI-STAR 100 FSAR for both horizontally and vertically oriented casks remain applicable.

References:

[I] HI-STAR 100 Storage FSAR, Holtec Report HI-2012610, Proposed Revision 4.

[2] HI-STAR I 00 Transport SAR, Holtec Report HI-951251, Revision 16.

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ATIACHMENT 1 TO HOLTEC LETIER 5014831 4-2 Provide additional discussion, descriptions, more specific incorporation by reference, or thermal analyses, to address how the physical attributes of the horizontal emplacement structure affects the thermal performance characteristics of the HI-ST AR 100 Cask Storage System when emplaced in a horizontal orientation, for normal, off-normal, and accident conditions.

In its first RAI, staff sought additional design information for the emplacement structure to be used to maintain the cask in a horizontal orientation. In its response, Holtec stated that it considers the proposed horizontal emplacement structure as not important to safety because it has analyzed the effect of cask drops from a height higher than the proposed height of the horizontal emplacement structure. However, in its response, Holtec does not discuss or evaluate the effects that this horizontal emplacement structure may have on the thermal performance of the cask or if it presents unique boundary conditions that need to be considered.

The staff needs additional information, either through design drawings, detailed descriptions, incorporation by reference, or thermal analyses, to verify that the boundary conditions accorded by the horizontal emplacement structure do not affect the thermal performance characteristics of the HI-STAR 100 in storage. The applicant should ensure that the most bounding MPC type is addressed. Because the horizontal emplacement of the HI-STAR 100 System has not been previously discussed or analyzed by the applicant, the method by which a HI-STAR 100 cask system would be placed on a storage pad at an ISFSI or interim storage facility is not known. The means of emplacement are an important element in determining off-normal and accident conditions that could occur during the movement of the HI-STAR 100 cask system to its storage configuration. Postulated off-normal and accident conditions (including a fire during the movement evolution, or a seismic event during storage, for example) would be different for a cask being placed in a horizontal vs. a vertical storage configuration.

The off-normal and accident conditions that could occur during the emplacement of the HI-STAR 100 cask system in a horizontal storage configuration should be considered and analyzed to demonstrate that the cask maintains its safety functions under these conditions. The emplacement structure, and its effect on the cask system, should also be considered in these analyses. If the applicant chooses to provide additional justification or incorporation by reference to address the staffs request, it should ensure that the information provided is thoroughly discussed and/or properly referenced in its proposed FSAR revision. Alternatively, if the applicant chooses to provide additional thermal analyses to address the staffs request, the applicant should submit any associated input and output files with its response.

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

Holtec Response: In the horizontal orientation for storage, the HI-ST AR I 00 is supported by saddle-type suppo11s located near the cask's extremities as shown in the following figures. As can be seen from the figures below, the saddles cover on the order of 40% of the cask circumference. Metal tie-down straps wrap around the remainder of the circumference at the same axial locations to secure the cask to the saddles. A tilting plate bolted to the cask base surface assists in rotating the cask from vertical to horizontal, and is left in place afterwards to provide additional gamma and neutron shielding.

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ATIACHMENT 1 TO HOLTEC LETIER 5014831 H~STAR 100STORAOE SUPPORT FRAME SUPPORT SADDLES H-STAR 100 TIE DOWN STRAP ASSEMBLY

~STAR 100 STORAOE SUPPORT FR.I.ME The relevant dimensions of the saddle supports and tie-down straps are listed in the following table.

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ATIACHMENT 1 TO HOLTEC LEDER 5014831 Table 4-2.1: Horizontal Emplacement Structure Dimensions Dimension SJ Value U.S. Value Saddle Center-to-Center Spacing 3632 mm 143 in Saddle Radius 1226 mm 48 9/32 in Saddle Arc Length 140 deg.

140 deg.

Saddle Width 290 mm 11 13/32 in Cask Centerline Height 1780 mm 70 1/8 in Tie-Down Strap Width 230 mm 91/16in Tie-Down Strap Radius 1244 mm 48 3/ 16 in Tie-Down Strap Thickness 25111111 31 /32 in These saddle dimensions shall be used whenever the HI-STAR I 00 cask is held horizontally.

The above figures and horizontal emplacement structure dimensions will be added to the FSAR.

As can be inferred from the above figure, the configuration of the HI-STAR I 00 cask in horizontal storage emulates its configuration in transport, with the notable difference that there is are no impact limiters to reduce the rejection of heat from the cask's ends. This deduction is borne out by the Fluent analysis summarized below.

Normal Conditions of Horizontal Storage Thermal evaluations of the horizontally disposed HI-STAR I 00 cask positioned on the above saddle supports was performed for both MPC-68 and MPC-32 cases under their respective Licensing Basis heat loads. These evaluations are performed using the methodology described in Section 3.4 of the HI-STAR I 00 SAR. This methodology is consistently used for evaluating all horizontally-oriented casks, whether in storage or transportation. The following tables present comparisons of normal horizontal storage and normal horizontal transport (the latter excerpted from the HI-STAR 100 SAR Tables 3.4.10 and 3.4.11) for PWR and BWR canisters, respectively. Results for both fission product barriers (i.e., the cladding of intact fuel and the MPC confinement boundary) are presented.

Table 4-2.2: HI-ST AR 100 with BWR Canister Normal Transport Incorporated by Reference vs. Normal Storage and Allowables Normal Horizontal Normal Horizontal Normal Storage Transport Note 1 Storage Note 2 Allowable Note J Ambient Temperature ormal Condition 100°F 80°F NIA Component Temperatures Fuel Cladding 713°F 639°F 752°F MPC Shell 306°F 288°F 450°F Internal Pressure Note 4 MPC Cavity Pressure 85.8 psig 85.2 psig 100 psig 6

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ATTACHMENT 1 TO HOL TEC LETTER 5014831 Table 4-2.2: HI-STAR 100 with BWR Canister Normal Transport Incorporated by Reference vs. Normal Storage and Allowables Notes I. The temperature and MPC cavity pressure results for normal transport are incorporated by reference from Tables 3.4.11 and 3.4.15 of HI-STAR I 00 SAR [2].

2. Thermal evaluations of a horizontal HI-STAR 100 cask positioned on the saddle supports was performed under the Licensing Basis heat loads. These evaluations are performed using the methodology descri bed in Section 3.4 of HI-STAR 100 SAR [2).

3. The temperature and pressure limits are extracted from Tables 2.2.3 and 2.2.1 of HI-STAR 100 FSAR [I).

4. The initial helium backfill pressure used to compute the confinement boundary pressures is 42.8 psig at a 70°F reference temperature, the maximum backfill level from Table 2-1 in Appendix A of the proposed technical specifications.

Table 4-2.3: HI-STAR 100 with PWR Canister Normal Transport Incorporated by Reference vs. Normal Storage and Allowables Normal Horizontal Normal Horizontal Normal Storage Transport Note 1 Storage Note 2 Allowable Note J Ambient Temperature Normal Condition 100°F 80°F NIA Component Temperatures Fuel Cladding 701 °F 698°F 752°F MPC Shell 315°F 306°F 450°F Internal Pressure Note 4 MPC Cavity Pressure 89.3 psig 89.2 psig I 00 psig Notes I. The temperature and MPC cavity pressure results for normal transport are incorporated by reference from Tables 3.4.10 and 3.4.15 of HI-STAR 100 SAR [2].

2. Thermal evaluations of a horizontal HI-STAR I 00 cask positioned on the saddle supports was performed under the Licensing Basis heat loads. These evaluations are performed using the methodology described in Section 3.4 of HI-STAR I 00 SAR [2).

3. The temperature and pressure limits are extracted from Tables 2.2.3 and 2.2.1 of HI-STAR 100 FSAR [I).

4. The initial helium backfill pressure used to compute the confinement boundary pressures is 42.8 psig at a 70°F reference temperature, the maximum backfill level from Table 2-1 in Appendix A of the proposed technical specifications.

As these two tables show, the thermal performance of the cask under horizontal storage conditions while mounted in the support structure is essentially the same as or somewhat superior to the horizontal transpo1i conditions incorporated by reference. More critically, it is shown that all fission product boundary temperatures and internal pressures remain below their respective limits. It is concluded, therefore, that the safety analysis for the transport condition 7

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ATTACHMENT 1 TO HOLTEC LETTER 5014831 does conservatively represent the thermal performance under the horizontal normal storage condition.

The above conclusion is based on the support system geometry described above, added to the FSAR, and adopted in the analysis.

Off-Normal and Accident Condition of Horizontal Storage Off-normal and accident conditions of storage, as tabulated below, are characterized by elevated ambient temperatures. The permissible temperatures are also correspondingly higher. A first-order estimate of the margin-to-limit for each component may be obtained by assuming that they will increase in direct proportion to the rise in the ambient temperature (a reasonable assumption for a natural convection controlled problem). The results summarized in the table below show that the margins for the off-normal and accident conditions are even larger than those for the normal condition of storage.

Table 4-2.4: Margins-to-Limit for HI-STAR 100 with PWR Canister in Horizontal Storage Under Various Conditions at Licensing Basis Heat Load Horizontal Normal Condition Horizontal Off-Normal Condition (80°F ambient)

(100°F ambient)

Component Component Margin to Estimated Margin to Temperature Limit Component Limit (from table Temperature above)

Fuel Cladding 698°F 54 718°F 340°F MPC Shell 306°F 144 326°F 449°F MPC Baseplate 289°F 111 309°F 466°F MPC Lid 171 °F 379 191 °F 584°F Horizontal Accident Condition (125°F ambient)

Estimated Margin to Component Limit Temperature Fuel Cladding 743°F 315°F MPC Shell 351 °F 424°F MPC Baseplate 334°F 441 °F MPC Lid 216°F 559°F Design Basis Fire Event The fire event for storage assumes the same flame temperature and all-enveloping fire as those required by transport (Part 71 ), but the latter has a longer duration (30 minutes vs. 5.1 minutes as stated in Paragraph 11.2.3.2 of the HI-STAR I 00 FSAR). As a result, the part temperatures under 8

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ATIACHMENT 1 TO HOLTEC LETIER 5014831 the storage fire event can be reasonably assumed to be bounded by the transport condition safety analysis reported in Section 3.5 of the HI-STAR 100 SAR (Report HI-951251). Because the thermal margins reported in the above SAR are quite large (see Table 3.5.4), it is concluded that the storage fire event will not adversely challenge the positive safety margins in the cask.

As is true of all site implementations, site-specific fire events that are not bounded by the FSA R will require a site specific IOCFR72.212 evaluation.

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ATIACHMENT 1 TO HOLTEC LETTER 5014831 4-3 Provide more detailed and specific references to the thermal analyses from the HI-STAR 100 Transportation Cask System Safety Analysis Report (SAR), including the specific chapters, sub-sections, or revision numbers) that will be used to demonstrate that the HI-STAR 100 Cask Storage System in a horizontal orientation meets the applicable limits and addresses the peak cladding temperature, SSCs maximum temperatures, thermal stresses, and canister cavity pressures; and provide additional discussions, within the HI-STAR 100 Cask Storage System FSAR, that explain how the referenced analyses are applicable to the horizontal storage configuration during normal, off-normal, and accident conditions of storage In its application and RAI response, the applicant seeks to incorporate by reference the thermal analyses from the SAR for the HI-STAR 100 Transportation Cask System.

However, the applicant does not provide the specific version or revision of the HI-STAR 100 Transportation Cask System SAR that it seeks to incorporate by reference, nor does it reference the specific sub-sections, chapters, or supplemental analyses that it intends to rely on to demonstrate compliance with 10 CFR Part 72 storage requirements. The applicant needs to provide clear and specific discussions, explanations, and/or justifications, within the HI-ST AR 100 Storage Cask System FSAR, that discuss how these referenced transportation thermal analyses are applicable to the horizontal storage configuration, and specifically indicate which portions of the thermal analyses from the transportation SAR are used to support the analysis of normal, off-normal, and accident conditions of storage, which address the peak cladding temperature, SSCs maximum temperatures, thermal stresses, and canister cavity pressures. In addition, the applicant should ensure that the thermal analyses adequately consider the effects of the horizontal emplacement structure (see RAI 4-2).

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

Holtec Response: Throughout Chapter 4 of the submitted proposed FSAR, references made to the HI-STAR I 00 transportation SAR cite the specific section or subsection or paragraph being referenced. In addition, every such citation also invokes Reference 4.0.1, which does identify the specific revision of the HI-STAR I 00 transportation SAR being referenced as Revision 15. To further improve convenience of access to the information incorporated by reference, a summary table like those provided by Holtec on other dockets (e.g., Table 4.0.1 in the HI-STORM UMAX FSAR) will be added to Section 4.0.

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ATIACHMENT 1 TO HOLTEC LEDER 5014831 4-4 Provide discussion and results of the thermal analysis in Section 4.4.1.1.7 of the FSAR that addresses the thermal interaction among casks in an array that ensures the cask array pitch or center-to-center spacing is bounding for all cask contents/MPCs, considers the most bounding combination of vertical and/or horizontal cask orientation, and provides justification for the most bounding combination of vertical and/or horizontal cask orientation.

The thermal interaction among casks in an array for the most bounding combination of vertical and/or horizontal cask orientation has not been described in Section 4.4.1.1.7, "Heat Rejection from Overpack Exterior Surfaces," of the HI-STAR 100 Cask Storage System FSAR. It is not clear if both horizontally and vertically oriented casks will be mixed, if the calculated cask array pitch (12 feet) is bounding for any combination of cask orientations, or if the minimum spacing is bounding for any type of canister models (e.g. MPC-24, MPC-32, and MPC-68).

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

Holtec Response: The required minimum cask-to-cask pitch of 12 feet in both orthogonal directions, specified in Section 1.4 of the proposed FSAR, is applicable to arrays of vertically-oriented casks only. For arrays of horizontally-oriented casks, a minimum lateral cask-to-cask pitch of 18 feet and a minimum ax ial cask-to-cask clearance of 5 feet is proposed (as shown in the following sketch).

LATERPl PITCH MPl. SPICING Vertically-oriented and horizontally-oriented casks will not be combined within an array, and a separation of at least 18 feet will be maintained between adjacent arrays.

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ATTACHMENT 1 TO HOLTEC LETTER 5014831 Evaluations of a horizontally-oriented HI-ST AR I 00 cask in the proposed array configuration are performed. All casks are mounted on the supports as described in the response to RA! 4-2, above. These evaluations are performed using the methodology described in Section 3.4 of the HI-STAR I 00 SAR. This methodology is consistently used for evaluating all horizontally-oriented casks, whether in storage or transportation. The effects of neighboring casks in the array is implemented using the same approach described in Subparagraph 4.4.1.1.7 of the HI-STAR I 00 FSAR; that is calculating cask-to-cask blockage factors, reducing the cask-to-ambient view factor by the blockage factor, and multiplying the cask surface emissivity by the reduced view factor. The following tables present normal storage performance results for B WR and PWR canisters. Results for both fission product barriers (i.e., the cladding of intact fuel and the MPC confinement boundary) are presented.

Table 4-4.1: HI-ST AR 100 with BWR Canister - Normal Horizontal Storage In An Array Normal Horizontal Storage Normal Storage Allowable (Note 1)

(Note 2)

Component Temperatures Fuel Cladding 644°F 752°F MPC Shell 298°F 450°F MPC Baseplate 281 °F 400°F MPC Lid 180°F 550°F Internal Pressure Note 3 MPC Cavity Pressure 86 psig I 00 psig Notes

1. Thermal evaluations of a horizontal HI-STAR I 00 cask positioned on the saddle supports was performed under the Licensing Basis heat loads. These evaluations are performed using the methodology described in Section 3.4 of HI-STAR 100 SAR [2].

2. The temperature and pressure limits are extracted from Tables 2.2.3 and 2.2.1 of HI-STAR IOOFSAR[l].

3. The initial helium backfill pressure used to compute the confinement boundary pressures is 42.8 psig at a 70°F reference temperature, the maximum backfill level from Table 2-1 in Appendix A of the proposed technical specifications.

Table 4-4.2: HI-STAR 100 with PWR Canister - Normal Horizontal Storage In An Array Normal Horizontal Storage Normal Storage Allowable (Note 1)

(Note 2)

Component Temperatures Fuel Cladding 703°F 752°F MPC Shell 316°F 450°F MPC Baseplate 300°F 400°F MPC Lid 180°F 550°F 12 Page 12 of 13

ATIACHMENT 1 TO HOL TEC LETTER 5014831 Internal Pressure Note3 MPC Cavity Pressure I

90 psig I

I 00 psig Notes

1. Thermal evaluations of a horizontal HI-ST AR 100 cask positioned on the saddle supports was performed under the Licensing Basis heat loads. These evaluations are performed using the methodology described in Section 3.4 of HI-STAR I 00 SAR [2].

2. The temperature and pressure limits are extracted from Tables 2.2.3 and 2.2.1 of HI-STAR IOOFSAR[l].

3. The initial helium backfill pressure used to compute the confinement boundary pressures is 42.8 psig at a 70°F reference temperature, the maximum backfill level from Table 2-1 in Appendix A of the proposed technical specifications.

As these two tables show, for the cask under horizontal storage conditions arrayed at the proposed pitches, all fission product boundary temperatures and internal pressures remain below their respective limits. The increase in the components' temperatures is minor. It is concluded, therefore, that the proposed separation between the horizontally stored casks is suitable for horizontal deployment of HI-ST AR I 00 Systems.

The cask pitch and supporting thermal evaluations will be added to the HI-STAR I 00 FSAR.

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ATIACHMENT 1 TO HOLTEC LETTER 5014831 Material Degradation Maintenance and Inspection Provisions Corrosion Structural Fatigue Effects Maintenance of Helium Atmosphere Allowable Fuel Cladding Temperatures Neutron Absorber Boron Depletion The adequacy of the HI-STAR I 00 System for its design life is discussed in sub-sections 3.4.10 and 3.4.11.

1.2.1.6 SuQQQrt Structure for Horizontal Casks, In the horizontal orientation for storage, the HI-STAR I 00 is supported by saddle-type supports located near the cask's extremities as shown in Figure 1.2.13. As can be seen in the figure, the saddles support the cask from below. Steel tie-down straps wrap around the remainder of the circumference at the same axial locations to secure the cask to the saddles. A tilting plate bolted to the cask base surface assists in rotating the cask from vertical to horizontal, and is left in lace afterwards to rovide additional gamma and neutron shieldin asic dimensions of the saddle supports and tie-down straps are presented in Table 1.2.7. These saddle dimensions shall be used whenever the HI-STAR 100 cask is held horizontally.

1.2.2 Operational Characteristics 1.2.2.1 Design Features The HI-STAR I 00 System is engineered to store different types of MPCs for varying PWR and BWR fuel characteristics.

The HI-STAR 100 System can safely store spent nuclear fuel with minimum cooling times. The maximum thermal decay heat load and SNF enrichments for each of the M PCs are identified in Chapter 2. The decay heat emitted by the spent nuclear fuel is dissipated in an entirely passive mode without any mechanical or forced cooling.

Both the free volume of the HI-STAR I 00 MPCs and the annulus between the external surface of the MPC and the inside surface of the overpack are ine1ted with commercially pure helium gas during the spent nuclear fuel loading operations. Table 1.2.2 specifies the helium pressure to be placed in the MPC internal cavity.

The primary heat transfer mechanisms are metal conduction and surface radiation for the HI-STAR I 00 System. The MPC internal helium atmosphere, in addition to providing a noncorrosive dry HI-STAR 100 FSAR REPORT HI-2012610 1.2-10 Page 1 of 15 Proposed Rev. 48 I

ATIACHMENT 1 TO HOLTEC LEDER 5014831 ABLE 1.2.7 IMENSIONS OF SUPPORT STRUCTURE FOR HORIZONTAL-ORI ENTATION CASKS imension Saddle Center-to-Center S Saddle Radius Saddle Arc Length Saddle Width Width Radius Thickness HI-STAR 100 FSAR REPORT HI-2012610 1780 mm 30mm 1244 mm 1.2-22 Page 2 of 15 5 mm

.S. Value 143 in 0 1/8 in 91/16in f48 3/16 in 1/32 in Proposed Rev. 48 I

ATIACHMENT 1 TO HOL TEC LEDER 5014831 IGURE 1.2.13 SUPPORT STRUCTURE FOR HORIZONTAL-ORIENTATION CASKS H~STAR 100 STORAGE SUPPORT FRAME SUPPORT SADDLES HI-STAR 100 FSAR REPORT HI-201 26 10 1.2-34 Page 3 of 15 TIE DOWN STRAP ASSEMBLY I-STAR 100 STORA.OE SUPPORT FRAME Proposed Rev. 48

ATTACHMENT 1 TO HOLTEC LETTER 5014831 1.4 GENERIC CASK ARRAYS The only system required for storage of the HI-STAR I 00 System is the loaded overpack itself. The HI-STAR I 00 System is stored in either a vertical or horizontal orientation. A typical vertical-orientation ISFSI storage pattern is illustrated in Figure 1.4.1. which shows an array in a rectangular layout pattern. The required center-to-center spacing between the modules (layout pitch), guided by heat transfer considerations, is specified to be 12 feet in both ortho onal directions. The itch may be increased to suit facility considerations.

typical horizontal-orientation ISFSI storage pattern is illustrated in Figure 1.4.2. In horizontal storage, the design-basis lateral distance between cask centerlines is 18 feet (5.5 m) to provide ractical access for handling equipment and the design-basis axial cask-to-cask clearance is 5 fee 1.5 m. Site-s eciftc layouts for arrays of horizontal casks are evaluated ursuant to 1 OCFR72.212.

ertically-oriented and horizontally-oriented casks will not be combined within an array, and a separation of at least 18 feet 5.5 m will be maintained between ad'acent grou s of vertical and orizontal casks.

HI-STAR 100 FSAR REPORT HI-2012610 Page 4 of 15 Proposed Rev. 48 I

ATTACHMENT 1 TO HOL TEC LETTER 5014831 FIGURE 1.4.1; HI-STAR 100 TYPICAL ISFSI STORAGE PATTERN OR VERTICAL TORAGE HI-STAR 100 FSAR REPORT Hl-2012610 Page 5 of 15 Proposed Rev. 48 I

ATIACHMENT 1 TO HOLTEC LEDER 5014831 LATERAL PITCH MPl SPPClf\\G FIGURE 1.4.2; HI-STAR 100 TYPICAL JSFSI STORAGE PATTERN FOR HORIZONTAL STORAGE HI-STAR 100 FSAR REPORT Hl-2012610 Page 6 of 15 Proposed Rev. 48 I

ATIACHMENT 1 TO HOLTEC LETIER 5014831 I-STAR 100 TRANSPORT SAR MATERIAL GERMANE TO HE EVALUATIONS IN THIS FSAR Sub Subsection 4.4.4 Subsection 4.4.5 HI-STAR FSAR REPORT Hl-2012610 ubject of Referenc uel Basket In-Plan aximum Temperatures nder Normal Storag Conditions aximum Internal Pressur

~ aximum Thermal Stress 4.0-3 Page 7 of 15 Figures 3.4.16 & 3.4.17 ables 3.4. l O & 3.4.11 ables 3.4.13 & 3.4.15 able 3.4.24 Proposed Rev. 48

ATTACHMENT 1 TO HOL TEC LETTER 5014831 model developed is shown in Figure 4.4.5. In this figure, a center HI-ST AR I 00 System cask is shown surrounded by two rows of casks on all sides. The ANSYS solution determines view factors between this most adversely located system in the middle with all other neighboring casks. A sum of all these individual blockages gives the total blockage factor. Thus, the view factor FI.A between this most adversely affected HI-STAR I 00 System and outside air is determined by the following relationship:

Fi.A= I-I F1.1s where F1.K is the view factor between HI-STAR 100 System I and a neighboring system K. This factor is determined by a series of ANSYS solutions as a function of ISFSI cask array pitch, and the results are shown in Figure 4.4.6.

For the surfaces of a horizontally-oriented cask, blocking factors due to adjacent casks are determined in the lateral direction (i.e., blocking by casks in parallel rows) and the axial direction (i.e., blocking of the lid surface of a cask by the base of an adjacent cask in the same row). Vie factors are determined for each of these surfaces ( cask side = lateral; cask lid = axial) using the same e uation for Fl,A above. The desi n-basis s acing from Section 1.4 is evaluated.

4.4.1.1.8 Determination of Solar Heat Input The intensity of solar radiation incident on an exposed surface depends on a number of time varying terms. The solar heat flux strongly depends upon the time of the day as well as on latitude and day of the year. Also, the presence of clouds and other atmospheric conditions (dust, haze, etc.) can significantly attenuate solar intensity levels. Rapp [4.4.2] has discussed the influence of such factors in considerable detail.

Consistent with the guidelines in NUREG-1536 [4.1.3], solar input to the exposed surfaces of the overpack is determined based on 12-hour insolation levels recommended in I OCFR7 I (averaged over a 24-hour period) and applied to the most adversely located cask after accounting for partial blockage of incident solar radiation on the lateral surfaces of the cask by surrounding casks. The blocking factor is identical to the radiative blocking considered for cooling of outside surfaces to the ambient environment. This is conservative compared to the case of an isolated cask with significantly improved radiative cooling and higher insolation levels because the cask is emitting much more heat than the insolation heat input. The imposed steady insolation level for the exposed top lid is based on a view factor equal to unity. The solar absorptivity of all exposed cask surfaces is assumed to be a conservatively bounding value of unity.

4.4.1.1.9 Effective Thermal Conductivity of Holtite Neutron Shielding Region In order to minimize heat transfer resistance limitations due to the poor thermal conductivity of the Holtite-A neutron shield material, a large number of thick radial channels of high strength and conductivity carbon steel material are embedded in the neutron shield region. The legs of the radial channels form highly conducting heat transfer paths for efficient heat removal. Each channel leg is welded to the outside surface of the outermost intermediate shell. Enclosure shell HI-STAR FSAR REPORT Hl-2012610 4.4-15 Page 8 of 15 Proposed Rev. 48 I

ATTACHMENT 1 TO HOL TEC LETTER 5014831 4.4.1.2 Test Model A detailed analytical model for thermal design of the HI-STAR I 00 System was developed using the FLUENT CFO code and the industry standard ANSYS modeling package, as discussed in Subparagraph 4.4.1.1. As discussed throughout this chapter and specifically in Subsection 4.4.6, the analysis incorporates significant conservatisms so as to predict the fuel cladding temperature with considerable margins. Furthermore, compliance with specified limits of operation is demonstrated with adequate margins. In view of these considerations, the HI-STAR I 00 System thermal design complies with the thermal criteria set forth in the design basis (Sections 2. 1 and 2.2) for long-term storage under normal conditions. Additional experimental verification of the thermal design is therefore not required.

4.4.2 4.4.2.1 Maximum Temperatures Maximum Temperatures Under Normal Storage Conditions The MPC basket designs developed for the HI-STAR I 00 System have been analyzed to determine the temperature distribution under long-term normal storage conditions. The MPC baskets are considered to be loaded at design basis maximum heat loads with PWR or BWR fuel assemblies, as appropriate. The systems are considered to be arranged in an ISFSI array and subjected to design basis normal ambient conditions with insolation.

Applying the radiative blocking factor applicable for the worst case cask location, converged temperature contours are shown in Figures 4.4.17 and 4.4.18 for the MPC-24, and MPC-68 basket designs in a vertical orientation. The temperatures in these two figures are in degrees Kelvin. Analogous figures for horizontal orientation storage of the MPC-24 and MPC-68 are presented in Figures 3.4.16 and 3.4.17 of the HI-STAR 100 transportation SAR. The calculated temperatures presented in this chapter are based on an array of analyses that incorporate many conservatisms. As such, the calculated temperatures are upper bound values which would exceed actual temperatures.

The maximum fuel clad temperatures for zircaloy clad fuel assemblies in vertically-oriented casks are listed in Tables 4.4.10 and 4.4.11, which also summarize maximum calculated temperatures in different parts of the HI-STAR 100 System. Figures 4.4.21 and 4.4.22 show the axial temperature variation of the hottest fuel rod in the MPC-24 and MPC-68 basket designs, respectively. Figures 4.4.24 and 4.4.25 show the radial temperature profile in the MPC-24 and MPC-68 basket designs, respectively, in the horizontal plane where maximum fuel cladding temperature is indicated.

pplying the radiative blocking factor applicable for the worst case cask location, the maximum fuel clad temperature for zircaloy clad fuel assemblies in an MPC-32 in a vertically-oriented HI-STAR 100 System is listed in Table 4.4.12, which also summarizes maximum calculated tern eratures in different arts of the HI-STAR 100 System.

Comparing the fuel cladding temperatures and the temperatures of the bounding confinemen boundary com onent (the MPC shell in Tables 4.4.11 and 4.4.12, the MPC-68 results in higher HI-STAR FSAR REPORT Hl-2012610 4.4-26 Page 9 of 15 Proposed Rev. 48

ATIACHMENT 1 TO HOL TEC LETTER 5014831 temperatures than the MPC-32. It is therefore concluded that the MPC-68 bounds the MPC-32 hen both are in ve11icall -oriented casks.

The maximum fuel clad temperatures for zircaloy clad fuel assemblies in horizontally-oriented casks are listed in Tables 3.4.10 and 3.4.11 of the HI-STAR 100 transportation SAR 4.0. 1,

which also summarize maximum calculated tern eratures in different arts of the HJ-STAR 100 System. Comparing the fuel cladding temperatures and the temperatures of the boundin, confinement boundary component (the MPC shell) in these two SAR tables, the MPC-68 results in higher temperatures than the MPC-32. It is therefore concluded that the MPC-68 bounds the MPC-32 when both are in horizontally-oriented casks.

he horizontally-oriented casks are supported by structures that holds the casks and prevents their movement during design-basis events. This structure covers the cask surface at two locations along its length as shown in Figure 1.2.13. The transportation thermal performance incorporated by reference from the HI-STAR I 00 SAR is compared to the normal storage condition with due consideration of the suppo1t structure, as shown in Table 4.4.26. As this table shows, the thermal performance of the cask under horizontal storage conditions while mounted in the support structure is essentially the same as or somewhat superior to the horizontal transport conditions incorporated by reference. More critically, it is shown that all fission roduct boundary temperatures and internal pressures remain below their respective limits. It is concluded, therefore, that the safety analysis for the transport condition does conservatively e resent the thermal erformance under the horizontal normal storage condition.

Similarly, the effects of array blocking for an array of horizontally-oriented casks is evaluated in the same manner as described in Subparagraph 4.4.1.1.7 for the normal storage condition and compared to the transportation thermal performance incorporated by reference from the HI-STAR 100 SAR in Table 4.4.27. As this table shows, for the cask under horizontal storage conditions arrayed at the proposed pitches, all fission product boundary temperatures and internal pressures remain below their respective limits. The increase in the components' temperatures is minor. It is concluded, therefore, that the proposed separation between th orizontally stored casks is suitable for horizontal de loyment of HI-STAR 100 Systems.

As discussed in Subsection 4.4.1.1.1, the thermal analysis is performed using a submodeling process where the results of an analysis on an individual component are incorporated into the analysis of a larger set of components. Specifically, the submodeling process yields directly computed fuel temperatures from which fuel basket temperatures are indirectly calculated. This modeling process differs from previous analytical approaches wherein the basket temperatures were evaluated first and then a basket-to-cladding temperature difference calculation by Wooten-Epstein or other means provided a basi for cladding temperatures. Subsection 4.4.1.1.2 describes the calculation of an effective fuel assembly thermal conductivity for an equivalent homogenous region. It is impo1tant to note that the result of this analysis is a function for thermal conductivity versus temperature. This function for fuel thermal conductivity is then input to the fuel basket effective thermal conductivity calculation described in Subsection 4.4.1.1.4. This calculation use a finite-element methodology, wherein each fuel cell region containing multiple finite-elements has temperature varying thermal conductivity properties. The resultant HI-STAR FSAR REPORT Hl-2012610 4.4-27 Page10of15 Proposed Rev. 48 I

ATIACHMENT 1 TO HOLTEC LETIER 5014831 able 4.4.12 HI-STAR JOO SYSTEM LONG-TERM VERTICAL ORIENTATION ORMAL STORAGEt MAXI MUM TEM PERATURES 32-PWR ASSEMBLIES, MPC Normal Condition Over ack Bolted Closure Platett t

t t Ambient Temperature = 80°F (27°C)

Cask Array Pitch = 3 x Cask Radius = 12 ft. (3.66 m)

Overpack closure plate and vent/drain port plug seals normal condition design temperature is 400°F (204°C). The maximum seals temperatures are bounded by the reported closure plate and bottom plate maximum temperatures. Consequently, a large margin of safety exists to permit safe operation of seals in the overpack helium retention boundary.

HI-STAR FSAR REPORT Hl-2012610 Proposed Rev. 48 I 4.4-44 Page 11 of 15

t ATIACHMENT 1 TO HOLTEC LEDER 5014831 Table 4.4.15

SUMMARY

OF MPC CONFINEME T BOU DARY PRESSURESt FOR NORMAL VERTICAL ORIENTATION LONG-TERM STORAGE Condition Pressure (psig [kPa])

MPC-24tt:

Initial backfill (at 70°F / 21°C) 22.2 [153]

Normal condition 43.8 [302]

With I% rods rupture 44.3 [305]

With I 0% rods rupture 49.1 [339]

With I 00% rods rupture 97.3 [671]

MPC-68:

Initial backfill (at70'F /21°C) 28.5 [197]

Normal condition 57.5 [396]

With 1 % rods rupture 57.8 [399]

With I 0% rods rupture 60.2 [415]

With I 00% rods rupture 84.6 [583]

MPC-32n :1 nitial backfill (at 70°F I 21 °C 0.3 140 Normal condition 42.9 []96J M'ith 1 % rods ru ture

=

~3.4 299 M'ith I 0% rods rupture 48.1 332

~ith I 00% rods rupture ::J 99.0 l683J Pressure analysis is based on NUREG-1536 criteria (i.e., 100% of rods fill gas and 30% of radioactive gases are available for release from a ruptured rod).

tt tt PWR fuel storage includes hypothetical BPRA rods rupture in the pressure calculations.

PWR fuel storage includes hypothetical BPRA rods rupture in the pressure calculations.

HI-STAR FSAR REPORT HI-2012610 4.4-47 Page 12 of 15 Proposed Rev. 48

ATIACHMENT 1 TO HOL TEC LETTER 5014831 able 4.4.26 COMPARISON OF TRANSPORTATION RESULTS INCORPORAl ED BY REFERENC WITH NORMAL HORIZONTAL STORAGE ON SUPPORT STRUCTURE, ormal Trans ort Incorporated by Reference vs. Normal Stora c and Allowables Normal Condit ion

• uel Cladding PC Shell PC Cavity Pressure ormal Condition PC Shell PC Cavity Pressure Notes I-STAR 100 with BWR Caniste ormal Horizontal Storage :\\'ote 2 eratures 639°F 88°F Internal Pressure 85.8 sio 85 si I-STAR 100 with PWR Canister ormal Horizontal ormal Horizontal ran~ort Note 5 Storage Note 2 mbient Temperature 100°F 80°F Component Temperatures 01°F 698°F 315°F Internal Pressure 89.3 si 89.QSi ormal Storag

~ llowable :\\oteJ IA 52°F 450°F I 00 sigi ormal Storage llowable Note 3 IA 52°F I 00 psigi I.

The temperature and MPC cavity pressure resu lts for normal trans ort are inco orated by referenc from Tables 3.4.11 and 3.4.15 of HI-STAR 100 SAR 2 Thermal evaluations of a horizontal HI-STAR 100 cask positioned on the performed under the Licensing Basis heat loads. These evaluations are 1ethodology described in Section 3.4 of HI-STAR 100 SAR 2.

3. The tern erature and ressure limits are extracted from Tables 2.2.3 and 2.2.1 of HI-STAR JOO FSA I.

<i. The initial helium backfill pressure used to compute the confinement boundary pressures is 42.8 psia a a 70°F reference temperature, the maximum backfill level from Table 2-I in A end ix A of the ro osed technical s ecifications.

5. The temperature and MPC cavity pressure results for normal trans ort are incor orated by referenc 1from Tables 3.4.10 and 3.4.15 of HI-STAR 100 SAR (n HI-STAR FSAR REPORT Hl-2012610 4.4-58 Page 13 of 15 Proposed Rev. 48 I

ATTACHMENT 1 TO HOL TEC LETTER 5014831 ABLE 4.4.2'Z OMPARISON OF fRANSPORTATION RESULTS INCORPORATED BY REFERENCE ITH NORMAL I IORIZONTAL STORAGE OF AN ARRAY OF CASKS Fuel Cladding PC Shell PC Baseplat PC Lid PC Cavity Pressure PC Cavity Pressure ormal Horizontal Storage In An Arra '

I-STAR 100 with BWR Caniste ormal Horizontal Stora (Note 1)

Com nternal Pressure ote

~I-STAR 100 with PWR Canister ormal Horizontal Storag (Note 1)

Component Tem_peratures 703° 316° 300° 180° nternal Pressure ote3 90 si 52°F

~W0°F 50°F 100 psi ormal Storage Allowable

[Note 2) 52°F ij50°F 00°F 550°F 100 si Thermal evaluations of a horizontal HI-ST AR I 00 cask positioned on the saddle supports was perfonned nder the Licensing Basis heat loads. These evaluations are erfonned using the methodology described in Section 3.4 of HI-STAR 100 SAR [2.

2.

The tern erature and ressure limits are extracted from Tables 2.2.3 and 2.2.1 of HI-STAR I 00 FSA I.

3.

The initial helium backfill pressure used to compute the confinement boundary pressures is 42.8 psia at 0°F reference temperature, the maximum backfill level from Table 2-1 in A endix A of the ro osed technical specifications.

HI-STAR FSAR REPORT Hl-20 12610 4.4-59 Page 14 of 15 Proposed Rev. 4 8 I

ATIACHMENT 1 TO HOLTEC LEDER 5014831 For vertically-oriented HI-STAR I 00 Systems, the maximum temperatures for components that have temperatures close to their design basis temperatures are listed in Tables 4.4. 10 and 4.4.1 I. These temperatures are con ervatively calculated at an environmental temperature of 80°F (27°C). The maximum off-normal environmental temperature is I 00°F (38°C). which is an increase of 20°F (11 °C). The bounding off-normal component temperatures are calculated by adding 20°F (1 1 °C) to the maximum normal temperatures from the highest component temperature from either the MPC-68 or the MPC-24 (whichever bounds). Table 11.1.1 lists the maximum off-normal temperatures. As illustrated by the table, all the maximum off-normal temperatures are well below the off-normal condition design basis temperatures. Under these conditions, the HI-STAR I 00 ystem maximum off-normal temperatures meet the design requirements specified in Table 2.2.3.

For horizontal ly-oriented systems, Chapter 3 the HI-STAR 100 trans ort SAR considers 100°F 38°C as the normal condition ambient tern erature. As described in Section 4.4.2, however, this transport condition is bounding for nonnal storage conditions. Therefore, it is necessary to increase the horizontal transport temperatures by 20°F for account for off-normal conditions of storage. Table 11.1. lists the tern eratures and all are well below off-normal condition design basis tern eratures.

In addition, the off-normal environmental temperature generates a pressure which is evaluated in Section 11.1.1. The off-normal MPC cavity pressure is less than the design basis nonnal/off-normal pressures listed in Table 2.2.1.

The off-normal event considering an environmental temperature of -40°F (-40°C), no decay heat, and no solar insolation for a duration sufficient to reach thermal equilibrium is evaluated with respect to material design temperatures. The HI-STAR I 00 System is conservatively assumed to reach -40°F (-40°C) throughout the structure. A II structural analysis is performed at the material design basis temperature, which is set higher than the component would experience with the design basis heat load under normal conditions. Assuming the HI-STAR I 00 System is -40°F (-40°C) would only serve to increase the safety margins as the material strength increases with decreasing temperatures. Subsection 3.1.2.3 details the structural analysis performed to evaluate brittle fracture at the lowest service temperature. Subsection 3.4.5 provides a structural evaluation of the effects of an environmental temperature of -40°F (-40°C) and demonstrates that there is no reduction in the performance of the HI-STAR I 00 System. Based on this evaluation, it is concluded that the off-normal environmental temperatures do not affect the safe operation of the HI-STAR 100 System.

Structural The effect on the MPC for the maximum off-normal temperature condition is an increase in the internal pressure. As shown in Section 11. l. l.3, the resultant pressure is wel I below the normal/off-normal design pressure of I 00 psig (689 kPa) used in the structural analysis. The effect of the minimum off-normal temperature conditions results in an evaluation of the potential for brittle fracture which is discussed in Section 3.1.2.3.

HI-STAR FSAR REPORT Hl-2012610 I 1.1-6 Page 15 of 15 Proposed Rev. 48 I