ML20269A428

Attachment 2 to Holtec Letter 5014908 - HI-STORM 100 FSAR Proposed Changed Pages (Non-Proprietary)

ML20269A428
Person / Time
Site:	Holtec
Issue date:	09/25/2020
From:	Holtec
To:	Office of Nuclear Material Safety and Safeguards
Shared Package
ML20269A425	List: ML20269A426 ML20269A428 ML20269A430
References
5014908
Download: ML20269A428 (5)

Text

ATTACHMENT 2 TO HOLTEC LETTER 5014908 4.II.4.6 Fuel Storage in DFI/DFCs As defined in Table 2.II.1.7 damaged fuel may be stored in Damaged Fuel Isolators (DFI) and Damaged Fuel Containers (DFC) in the peripheral locations of MPC-32M. As DFCs and DFIs are equipped with screens and DFCs use square shaped boxes for storing fuel these affect flow resistance and lateral dissipation of heat. For this reason DFIs and DFCs are limited to locating in the cold peripheral regions of the canister. In design space a suitable heat load penalty is defined in the specifications permitting DFI/DFC storage (Table 2.II.1.7) and evaluated in the supporting Calculation Package [4.II.7]. The results show the maximum fuel temperature obtained under DFI/DFC storage are essentially same as or bounded by temperatures computed under intact or undamaged fuel storage (See Table 4.II.4.1).

MPC-32/68 Version 1 canisters permit damaged fuel or fuel debris storage in DFCs (See Table 1.II.2.3).

The number, location and heat load allowances for DFC storage are same as for previously certified MPC-32/68 canisters. As the thermal design of MPC-32/68 Version 1 canisters evaluated in this Supplement are bounded by previously certified canisters no additional thermal analyses are necessary to support DFC storage in Version 1 canisters.

4.II.4.7 Storage Under Sheltered Configuration As stated in Section 1.II.2.1, the HI-STORM 100S Version Eis system is permitted for storage in a sheltered configuration. In a sheltered configuration, an array of casks are placed inside a storage building. Placing casks inside a building could potentially result in air temperatures higher than outside the building. Therefore, if the casks are placed in a sheltered configuration for long-term storage, site-specific evaluations shall be performed to demonstrate that the acceptance criteria are satisfied. In order to compute the bounding PCT, component temperatures and MPC pressure, site-specific evaluations of the HI-STORM system under a sheltered configuration shall be performed in two steps. In the first step, a 3D model of the cask array inside the building is constructed to compute the environmental parameters (sink temperatures). In the second step, a calculation of single cask is performed using the licensing basis thermal model described in Section 4.II.4.1 and the maximum tempreatures and pressures are computed for the most bounding cask within the building. The methodology is described below:

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PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390

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HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 17F REPORT HI-2002444 4-II-18 1 of 5

ATTACHMENT 2 TO HOLTEC LETTER 5014908

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PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390

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An example evaluation is performed for the long-term storage of HI-STORM 100 Version E system under sheltered configuration following the methodology described above. A 3D half symmetric model is constructed for an example storage building as shown in Figure 4.II.4.1. An 8x5 cask array with a square pitch of 15 feet is adopted and the sink temperatures are computed per Step I described above. The detailed single cask model (Step II) is evaluated for the indoor configuration using the computed sink temperatures to obtain the maximum temperatures and pressures.

The detailed description of the example evaluation is documented in the companion calculation package

[4.II.7]. The computed temperatures and pressures for the assumed sheltered configuration, following the HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 17F REPORT HI-2002444 4-II-19 2 of 5

ATTACHMENT 2 TO HOLTEC LETTER 5014908 Table 4.II.4.8 Peak Cladding Temperatures and MPC-32M Pressures under Sheltered Configuration PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390 HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 17F REPORT HI-2002444 4-II-27 3 of 5

ATTACHMENT 2 TO HOLTEC LETTER 5014908 and MPC-32/68 Version 1 canisters at or below which fuel and component temperatures remain below accident limits. To identify and clear blockages mandatory 30-Day surveillance for casks meeting the threshold heat load criteria incorporated in the Technical Specifications.

4.II.7.2 Loss of Ventilation Under Sheltered Configuration

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PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390

] The methodology delineated therein is adopted and steady state evaluations are performed to compute the ambient air temperatures inside the building. The resulting ambient sink temperatures are adopted in the evaluation of HI-STORM system stored inside the building. The computed component temperatures and MPC cavity pressure are presented in Table 4.II.7.8. The temperatures comply with Table 2.II.2.9 accident limits. The co-incident MPC pressure are compared with the accident design pressure (Table 1.II.2.3) and shows a positive safety margin.

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 17F REPORT HI-2002444 4-II-51 4 of 5

ATTACHMENT 2 TO HOLTEC LETTER 5014908 Table 4.II.7.8 Loss of Building Ventilation under Sheltered Configuration PROPRIETARY INFORMATION WITHHELD IN ACCORDANCE WITH 10CFR2.390 HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 17F REPORT HI-2002444 4-II-56 5 of 5