ML21068A386

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HI-STORM 100 Amendment 16 Certificate of Compliance, Appendix A-100U Reorganization
ML21068A386
Person / Time
Site: Holtec
Issue date: 03/09/2021
From:
Holtec
To:
Office of Nuclear Material Safety and Safeguards
Shared Package
ML21068A360 List:
References
5014917
Download: ML21068A386 (13)
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Attachment 24 to Holtec Letter 5014917 PROPOSED CERTIFICATE OF COMPLIANCE NO. 1014 APPENDIX A - 100U INSPECTIONS, TESTS, AND EVALUATIONS FOR THE HI-STORM 100 CASK SYSTEM 1 of 13

Attachment 24 to Holtec Letter 5014917 TABLE OF CONTENTS 1 Inspections, Tests, and Evaluations ................................................................................. 1-1 1.1 Definitions ................................................................................................................. 1-1 1.2 Neutron Absorber Tests ............................................................................................ 1-1 1.2.1 Requirements .................................................................................................... 1-1 1.2.2 Design Important to Neutron Absorber Tests ..................................................... 1-1 1.3 Combustible Gas Monitoring During MPC Lid Welding and Cutting .......................... 1-1 1.4 Special Requirements for First System in Place........................................................ 1-2 1.4.1 Storage Configuration ........................................................................................ 1-2 1.4.2 Transfer Configuration ....................................................................................... 1-2 1.5 Pre-Operational Testing and Training ....................................................................... 1-2 1.5.1 Dry Run Training Exercise ................................................................................. 1-2 1.6 Periodic Corrosion Inspections for Underground Systems ........................................ 1-3 1.6.1 Inspections ........................................................................................................ 1-4 1.6.2 Inspection Criteria .............................................................................................. 1-4 2 Site .................................................................................................................................. 2-1 2.1 Site Specific Parameters and Analyses..................................................................... 2-1 2.2 Forced Helium Dehydration System .......................................................................... 2-4 2.2.1 System Description ............................................................................................ 2-4 2.2.2 Design Criteria ................................................................................................... 2-4 2.2.3 Fuel Cladding Temperature ............................................................................... 2-4 2.2.4 Pressure Monitoring During FHD Malfunction .................................................... 2-5 2.3 Corrosion Mitigation Measures.................................................................................. 2-5 3 Applicable Code Paragraphs for Underground VVMs ...................................................... 3-1 TABLES Table 2-1: Load Combinations for the Top Surface Pad, VVM Interface Pad, Support Foundation Pad, and the Retaining Wall Per ACI-318 (2005) .................................................................... 2-2 Table 2-2: Values of Principle Design Parameters for the Underground ISFSI ........................ 2-2 Table 3-1: Applicable Code Paragraphs for Underground VVMs............................................. 3-1 Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U i 2 of 13

Attachment 24 to Holtec Letter 5014917 1 INSPECTIONS, TESTS, AND EVALUATIONS Written cask acceptance tests and maintenance program shall be prepared consistent with the technical basis described in Chapter 9 of the FSAR.

1.1 Definitions Refer to Appendix B for Definitions.

1.2 Neutron Absorber Tests 1.2.1 Requirements Section 9.1.5.3 of the HI-STORM 100 FSAR is hereby incorporated by reference into the HI-STORM 100 CoC. The minimum 10B for the neutron absorber shall meet the minimum requirements for each MPC model specified in Sections 1.2.2.1 through 1.2.2.4 below.

1.2.2 Design Important to Neutron Absorber Tests 1.2.2.1 MPC-24

1. Flux trap size: 1.09 in.
2. 10B loading in the neutron absorbers: 0.0267 g/cm2 (Boral) and 0.0223 g/cm 2 (METAMIC) 1.2.2.2 MPC-68
1. Fuel cell pitch: 6.43 in.
2. 10B loading in the neutron absorbers: 0.0372 g/cm2 (Boral) and 0.0310 g/cm 2 (METAMIC) 1.2.2.3 MPC-24E
1. Flux trap size:
i. Cells 3, 6, 19, and 22: 0.776 inch ii. All Other Cells: 1.076 inches
2. 10B loading in the neutron absorbers: 0.0372 g/cm2 (Boral) and 0.0310 g/cm2 (METAMIC) 1.2.2.4 MPC-32
1. Fuel cell pitch: 9.158 inches
2. 10B loading in the neutron absorbers: 0.0372 g/cm2 (Boral) and 0.0310 g/cm2 (METAMIC) 1.2.2.5 Fuel spacers shall be sized to ensure that the active fuel region of intact fuel assemblies remains within the neutron poison region of the MPC basket with water in the MPC.

1.2.2.6 The B4C content in METAMIC shall be 33.0 wt.%

1.3 Combustible Gas Monitoring During MPC Lid Welding and Cutting During MPC lid-to-shell welding and cutting operations, combustible gas monitoring of the space under the MPC lid is required, to ensure that there is no combustible mixture present.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 1-1 3 of 13

Attachment 24 to Holtec Letter 5014917 1.4 Special Requirements for First System in Place 1.4.1 Storage Configuration For the storage configuration, each user of a HI-STORM 100 Cask and HI-STORM 100U Cask with a heat load equal to or greater than 20 kW shall perform a thermal validation test in which the user measures the total air mass flow rate through the cask system using direct measurements of air velocity in the inlet vents. The user shall then perform an analysis of the cask system with the taken measurements to demonstrate that the measurements validate the analytic methods described in Chapter 4 of the FSAR. The thermal validation test and analysis results shall be submitted in a letter report to the NRC pursuant to 10 CFR 72.4 within 180 days of the users loading of the first cask with a heat load equal to or greater than 20 kW. To satisfy this condition for casks of the same system type (i.e., HI-STORM 100 casks, HI-STORM 100U casks), in lieu of additional submittals pursuant to 10 CFR 72.4, users may document in their 72.212 report a previously performed test and analysis submitted by letter report to the NRC that demonstrates validation of the analytic methods described in Chapter 4 of the FSAR.

This condition does not apply to the HI-STORM 100 UVH overpack.

1.4.2 Transfer Configuration For the transfer configuration, each user of the HI-STORM 100 Cask and HI-STORM 100U Cask shall procure, if necessary, a Supplemental Cooling System (SCS) capable of providing the thermal-hydraulic characteristics (coolant temperature at the annulus inlet, coolant temperature located at the annulus outlet, and coolant flow rate) that will ensure that thermal limits (described in Appendix 2.C of the FSAR) are not exceeded during transfer operations. The thermal-hydraulic characteristics of the SCS shall be determined using the analytical methods described in Chapter 4 for the transfer configuration. For the transfer configuration, each first time user shall measure the SCS thermal-hydraulic characteristics to validate the performance of the SCS. The SCS analysis and validation shall be documented in an update to the 72.212 report within 180 days of the users first transfer operation with the SCS.

This does not apply to the MPC-68M or the MPC-32M.

1.5 Pre-Operational Testing and Training 1.5.1 Dry Run Training Exercise A dry run training exercise of the loading, closure, handling, unloading, and transfer of the HI-STORM 100 Cask System shall be conducted by the licensee prior to the first use of the system to load spent fuel assemblies. The training exercise shall not be conducted with spent fuel in the MPC. The dry run may be performed in an alternate step sequence from the actual procedures, but all steps must be performed. The dry run shall include, but is not limited to the following:

a. Moving the MPC and the transfer cask into the spent fuel pool or cask loading Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 1-2 4 of 13

Attachment 24 to Holtec Letter 5014917 pool.

b. Preparation of the HI-STORM 100 Cask System for fuel loading.
c. Selection and verification of specific fuel assemblies to ensure type conformance.
d. Loading specific assemblies and placing assemblies into the MPC (using a dummy fuel assembly), including appropriate independent verification.
e. Remote installation of the MPC lid and removal of the MPC and transfer cask from the spent fuel pool or cask loading pool.
f. MPC welding, NDE inspections, pressure testing, draining, moisture removal (by vacuum drying or forced helium dehydration, as applicable), and helium backfilling. (A mockup may be used for this dry-run exercise.)
g. Operation of the HI-STORM 100 SCS or equivalent system, if applicable.
h. Transfer cask upending/downending on the horizontal transfer trailer or other transfer device, as applicable to the sites cask handling arrangement.
i. Transfer of the MPC from the transfer cask to the overpack/VVM.
j. Placement of the HI-STORM 100 Cask System at the ISFSI, for aboveground systems only.
k. HI-STORM 100 Cask System unloading, including flooding MPC cavity, removing MPC lid welds. (A mockup may be used for this dry-run exercise.)

1.6 Periodic Corrosion Inspections for Underground Systems HI-STORM 100U VVM ISFSIs not employing an impressed current cathodic protection system shall be subject to visual and UT inspection of at least one representative VVM to check for significant corrosion of the CEC Container Shell and Bottom Plate at an interval not to exceed 20 years. The VVM chosen for inspection is not required to be in use or to have previously contained a loaded MPC. The VVM considered to be most vulnerable to corrosion degradation shall be selected for inspection. If significant corrosion is identified, either an evaluation to demonstrate sufficient continued structural integrity (sufficient for at least the remainder of the licensing period) shall be performed or the affected VVM shall be promptly scheduled for repair or decommissioning. Through wall corrosion shall not be permitted without promptly scheduling for repair or decommissioning. Promptness of repair or decommissioning shall be commensurate with the extent of degradation of the VVM but shall not exceed 3 years from the date of inspection.

If the representative VVM is determined to require repair or decommissioning, the next most vulnerable VVM shall be selected for inspection. This inspection process shall conclude when a VVM is found that does not require repair or decommissioning. Since the last VVM inspected is considered more prone to corrosion than the remaining un-inspected VVMs, the last VVM inspected becomes the representative VVM for the remaining VVMs.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 1-3 5 of 13

Attachment 24 to Holtec Letter 5014917 1.6.1 Inspections 1.6.1.1 Visual Inspection Visual inspection of the inner surfaces of the CEC Container Shell and Bottom Plate for indications of significant or through wall corrosion (i.e., holes).

1.6.1.2 UT Inspection 1.6.1.3 The UT inspection is performed on the inside surfaces of the CEC. A minimum of 16 data points shall be obtained, 4 near the top, 4 near the mid-height and 4 near the bottom of the CEC Container Shell all approximately 0, 90, 180, and 270 degrees apart; and 4 on the CEC Bottom Plate near the CEC Container Shell approximately 0, 90, 180, and 270 degrees apart. Locations where visual inspection has identified potentially significant corrosion shall also receive UT inspection. Locations suspected of significant corrosion may receive further UT inspection to determine the extent of corrosion.

1.6.2 Inspection Criteria General wall thinning exceeding 1/8 in depth and local pitting exceeding 1/4" in depth are conditions of significant corrosion.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 1-4 6 of 13

Attachment 24 to Holtec Letter 5014917 2 SITE 2.1 Site Specific Parameters and Analyses Site-specific parameters and analyses that will require verification by the system user are, as a minimum, as follows:

2.1.1.1 The temperature of 80º F is the maximum average yearly temperature.

2.1.1.2 The allowed temperature extremes, averaged over a 3-day period, shall be greater than

-40º F and less than 125º F.

2.1.1.3 The analyzed flood condition of 15 fps water velocity and a height of 125 feet of water (full submergence of the loaded cask) are not exceeded.

2.1.1.4 The potential for fire and explosion shall be addressed, based on site-specific considerations. The user shall demonstrate that the site-specific potential for fire is bounded by the fire conditions analyzed by the Certificate Holder, or an analysis of the site-specific fire considerations shall be performed.

2.1.1.5 The resultant zero period acceleration at the top of the grade and at the elevation of the Support Foundation Pad (SFP) at the host site (computed by the Newmarks rule as the sum of A+0.4*B+0.4*C, where A, B, C denote the free field ZPAs in the three orthogonal directions in decreasing magnitude, i.e., A B C) shall be less than or equal to 1.3 and 1.228, respectively.

2.1.1.6

a. The criteria used to qualify the protection of the reactor building base mat foundation at the nuclear plant shall also be used to insure that sub-grade supporting the SFP shall not violate the plants acceptance criteria for the potential of liquefaction.
b. The depth averaged densities and strain compatible shear wave velocities in the different regions of the subgrade shall meet the minimum requirements of Table 2-2.

2.1.1.7 The moment and shear capacities of the ISFSI Structures shall meet the structural requirements under the load combinations in Table 2-1.

2.1.1.8 Radiation Protection Space (RPS) as defined in Subsection 4.3.9 of Appendix B-100U, is intended to ensure that the subgrade material in and around the lateral space occupied by the VVMs remains essentially intact under all service conditions including during an excavation activity adjacent to the RPS.

2.1.1.9 The Support Foundation Pad (mat) for a VVM array established in any one construction campaign shall be of monolithic construction, to the extent practicable, to maximize the physical stability of the underground installation.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 2-1 7 of 13

Attachment 24 to Holtec Letter 5014917 Table 2-1: Load Combinations for the Top Surface Pad, VVM Interface Pad, Support Foundation Pad, and the Retaining Wall Per ACI-318 (2005)

Load Combination LC-1 1.4D LC-2 1.2D + 1.6L LC-3 1.2D + E + L where:

D: Dead Load including long-term differential settlement effects.

L: Live Load E: DBE for the Site Table 2-2: Values of Principle Design Parameters for the Underground ISFSI Thickness of the Support Foundation Pad, inch 33 (nominal)

Thickness of the VVM Interface Pad, inch (nominal) 34 Thickness of the Top Surface Pad, inch (nominal) 30 Thickness of Retaining Wall, inch (nominal) 24 Rebar Size* (min.) and Layout* (max) #11 @ 9" each face, each direction Rebar Concrete Cover (top and bottom)*, inch per 7.7.1 of ACI 318 (2005)

Compressive Strength of Concrete*, psi 4500 Shear Wave Velocity in the Subgrade lateral to the 500 VVM, fps (nominal)

Shear Wave Velocity in the Subgrade Below the 485 Support Foundation Pad, fps (nominal)

  • Applies to Support Foundation Pad, VVM Interface Pad, Top Surface Pad and Retaining Wall Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 2-2 8 of 13

Attachment 24 to Holtec Letter 5014917 2.1.1.10 Prior to an excavation activity contiguous to an RPS, a seismic qualification of the ISFSI in the structurally most vulnerable configuration (i.e., maximum amount of earth removed) shall be performed to verify that the stability of the SFP, the TSP and the shielding material within the RPS, with or without the Retaining Wall, is maintained. If a Retaining Wall is not installed in any side of the ISFSI then an Excavation Exclusion Zone shall be established inside which excavation is prohibited by performing an appropriate SSI analysis.

2.1.1.11 In cases where engineered features (i.e., berms and shield walls) are used to ensure that the requirements of 10 CFR 72.104(a) are met, such features are to be considered important to safety and must be evaluated to determine the applicable quality assurance category.

2.1.1.12 LOADING OPERATIONS, TRANSPORT OPERATIONS, and UNLOADING OPERATIONS shall only be conducted with working area ambient temperatures 0º F.

2.1.1.13 For those users whose site-specific design basis includes an event or events (e.g., flood) that result in the blockage of any VVM inlet or outlet air ducts for an extended period of time (i.e, longer than the total Completion Time of LCO 3.1.2), an analysis or evaluation may be performed to demonstrate adequate heat removal is available for the duration of the event. Adequate heat removal is defined as fuel cladding temperatures remaining below the short term temperature limit. If the analysis or evaluation is not performed, or if fuel cladding temperature limits are unable to be demonstrated by analysis or evaluation to remain below the short term temperature limit for the duration of the event, provisions shall be established to provide alternate means of cooling to accomplish this objective.

2.1.1.14 Users shall establish procedural and/or mechanical barriers to ensure that during LOADING OPERATIONS and UNLOADING OPERATIONS, either the fuel cladding is covered by water, or the MPC is filled with an inert gas.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 2-3 9 of 13

Attachment 24 to Holtec Letter 5014917 2.2 Forced Helium Dehydration System 2.2.1 System Description Use of a forced helium dehydration (FHD) system, (a closed-loop system) is an alternative to vacuum drying the MPC for moderate burnup fuel ( 45,000 MWD/MTU) with lower MPC heat load and for drying MPCs containing one or more high burnup fuel assemblies or higher MPC heat loads as indicated in Appendix B-100U Tables 3-1. The FHD system shall be designed for normal operation (i.e., excluding startup and shutdown ramps) in accordance with the criteria in Section 2.2.2.

2.2.2 Design Criteria 2.2.2.1 The temperature of the helium gas in the MPC shall be at least 15ºF higher than the saturation temperature at coincident pressure.

2.2.2.2 The pressure in the MPC cavity space shall be 60.3 psig (75 psia) during drying.

Backfill pressures shall be as described in Appendix B.

2.2.2.3 The hourly recirculation rate of helium shall be 10 times the nominal helium mass backfilled into the MPC for fuel storage operations.

2.2.2.4 The partial pressure of the water vapor in the MPC cavity will not exceed 3 torr. The limit is met if the gas temperature at the demoisturizer outlet is verified by measurement to remain 21ºF for a period of 30 minutes or if the dew point of the gas exiting the MPC is verified by measurement to remain 22.9ºF for 30 minutes.

2.2.2.5 The condensing module shall be designed to de-vaporize the recirculating helium gas to a dew point 120ºF.

2.2.2.6 The demoisturizing module shall be configured to be introduced into its helium conditioning function after the condensing module has been operated for the required length of time to assure that the bulk moisture vaporization in the MPC (defined as Phase 1 in FSAR Appendix 2.B) has been completed.

2.2.2.7 The helium circulator shall be sized to effect the minimum flow rate of circulation required by these design criteria.

2.2.2.8 The pre-heater module shall be engineered to ensure that the temperature of the helium gas in the MPC meets these design criteria.

2.2.3 Fuel Cladding Temperature A steady-state thermal analysis of the MPC under the forced helium flow scenario shall be performed using the methodology described in HI-STORM 100 FSAR Section 4.4, with due recognition of the forced convection process during FHD system operation. This analysis shall demonstrate that the peak temperature of the fuel cladding, under the most adverse condition of FHD system operation, is below the peak cladding temperature limit for normal conditions of storage for the applicable fuel type (PWR or BWR) and cooling time at the start of dry storage.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 2-4 10 of 13

Attachment 24 to Holtec Letter 5014917 2.2.4 Pressure Monitoring During FHD Malfunction During an FHD malfunction event, described in HI-STORM 100 FSAR Chapter 11 as a loss of helium circulation, the system pressure must be monitored to ensure that the conditions listed therein are met.

2.3 Corrosion Mitigation Measures The HI-STORM 100U VVM CEC Container Shell and Bottom Plate shall be protected from corrosion damage due to the corrosivity of the surrounding environment using the following means:

Implementation and Requirements of Corrosion Mitigation Measures Surrounding Corrosion Mitigation Measures Environments Corrosivity Coating Concrete Encasement Cathodic Protection (see note iv) (see note i) (see note ii) (see note iii)

Choice of either concrete encasement or cathodic Mild Required protection; or both Aggressive Required Optional Required Notes:

i. An exterior surface preservative (coating) applied on the CEC in accordance with the acceptance criteria set forth in the FSAR.

ii. Concrete encasement of the CEC external surfaces to establish a high pH buffer around the CEC metal mass in accordance with the requirements set forth in the FSAR.

iii. An impressed current cathodic protection system (ICCPS) in accordance with the design criteria set forth in the FSAR.

iv. Surrounding environment corrosivity is categorized as either mild or aggressive in accordance with the requirements set forth in the FSAR.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 2-5 11 of 13

Attachment 24 to Holtec Letter 5014917 3 APPLICABLE CODE PARAGRAPHS FOR UNDERGROUND VVMS Table 3-1: Applicable Code Paragraphs for Underground VVMs Item Code Explanation and Applicability Paragraph

1. Definition of primary and secondary NF-1215 members
2. Jurisdictional boundary NF-1133 The intervening elements are termed interfacing SSCs in this FSAR.
3. Certification of Material NF-2130(b) and Materials shall be certified to the (c) applicable Section II of the ASME Code or equivalent ASTM Specification.
4. Heat treatment of material NF-2170 and NF-2180
5. Storage of welding material NF-2400
6. Structural Analysis of Interfacing ACI 318-05 The VVM Interface Pad and Support SSCs Foundation are reinforced concrete structures. Loadings come from the external environment and from the VVM. Sections of the Code that may reasonably be applied to subterranean application are applicable.
7. Welding procedure Section IX
8. Welding material Section II
9. Loading conditions NF-3111
10. Allowable stress values NF-3112.3
11. Rolling and sliding supports NF-3424
12. Differential thermal expansion NF-3127
13. Stress analysis NF-3143 Provisions for stress analysis for NF-3380 Class 3 plate and shell supports and NF-3522 for linear supports are applicable for NF-3523 CEC shells and CLOSURE LID.
14. Cutting of plate stock NF-4211 NF-4211.1
15. Forming NF-4212
16. Forming tolerance NF-4221 Applies to the CEC Divider Shell and CEC Container Shell
17. Fitting and Aligning Tack Welds NF-4231 NF-4231.1
18. Alignment NF-4232
19. Storage of Welding Materials NF-4411
20. Cleanliness of Weld Surfaces NF-4412 Applies to structural and non-structural welds
21. Backing Strips, Peening NF-4421 Applies to structural and non-Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 3-1 12 of 13

Attachment 24 to Holtec Letter 5014917 Item Code Explanation and Applicability Paragraph NF-4422 structural welds

22. Pre-heating and Interpass NF-4611 Applies to structural and non-Temperature NF-4612 structural welds NF-4613
23. Non-Destructive Examination NF-5360 InvokesSection V
24. NDE Personnel Certification NF-5522 -

NF-5523 NF-5530 All references to the ASME Code refer to applicable sections of the 1995 edition with addenda through 1997, except for Code Sections V and IX, where the latest effective editions of ASME Code Sections V and IX, including addenda, may be used, provided a written reconciliation of the later edition against the 1995 Edition, including addenda, is performed by the certificate holder.

Certificate of Compliance No. 1014 Amendment No. 16 Appendix A-100U 3-2 13 of 13

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