ML15026A530

Calvert Cliffs Nuclear Power Plant Independent Spent Fuel Storage Installation Updated Safety Analysis Report, Revision 23. Chapter 1 - Introduction and General Description of Installation

ML15026A530
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CHAPTER 1 INTRODUCTION AND GENERAL DESCRIPTION OF INSTALLATION LIST OF EFFECTIVE PAGES PAGE REVISION PAGE REVISION CALVERT CLIFFS ISFSI USAR LEP 1-1 Rev. 23 LEP 1-1 23 1-i 22 1-ii 22 1-iii 15 1-iv 22 1.1-1 22 1.1-2 23 1.2-1 23 1.2-2 23 1.2-3 20 1.2-4 15 1.3-1 22 1.3-2 22 1.3-3 22 1.3-4 22 1.3-5 22 1.3-6 22 1.3-7 22 1.3-8 22 1.4-1 22 1.5-1 8 1.5-2 8 1.6-1 22 Figure 1.1-1 3 Figure 1.2-1 22 Figure 1.3-1 0 Figure 1.3-2 15 Figure 1.3-3 15 Figure 1.3-4 15 Figure 1.3-5 15 Figure 1.3-7 15

CHAPTER 1 INTRODUCTION AND GENERAL DESCRIPTION OF INSTALLATION TABLE OF CONTENTS PAGE CALVERT CLIFFS ISFSI USAR 1-i Rev. 22

1.0 INTRODUCTION

AND GENERAL DESCRIPTION OF INSTALLATION 1.1-1

1.1 INTRODUCTION

1.1-1 1.2 GENERAL DESCRIPTION OF INSTALLATION 1.2-1 1.2.1 GENERAL DESCRIPTION 1.2-1 1.2.2 PRINCIPAL SITE CHARACTERISTICS 1.2-1 1.2.3 PRINCIPAL DESIGN CRITERIA 1.2-1 1.2.4 OPERATING AND FUEL HANDLING SYSTEMS 1.2-1 1.2.5 SAFETY FEATURES 1.2-2 1.2.6 RADIOACTIVE WASTE AND AUXILIARY SYSTEMS 1.2-2 1.3 GENERAL SYSTEMS DESCRIPTIONS 1.3-1 1.3.1 SYSTEMS DESCRIPTIONS 1.3-1 1.3.1.1 Dry Shielded Canister Design 1.3-1 1.3.1.2 Horizontal Storage Module 1.3-2 1.3.1.3 Transfer Cask 1.3-6 1.3.1.4 Transfer Trailer 1.3-6 1.3.1.5 Transfer Cask Skid and Positioning System 1.3-6 1.3.1.6 Hydraulic Ram System 1.3-6 1.3.1.7 Vacuum Drying System 1.3-6 1.3.1.8 Closure Welding System 1.3.7 1.3.1.9 System Operation 1.3-7 1.4 IDENTIFICATION OF AGENTS AND CONTRACTORS 1.4-1 1.5 MATERIAL INCORPORATED BY REFERENCE 1.5-1

1.6 REFERENCES

1.6-1 CHAPTER 1 INTRODUCTION AND GENERAL DESCRIPTION OF INSTALLATION LIST OF TABLES TABLE PAGE CALVERT CLIFFS ISFSI USAR 1-ii Rev. 22 1.2-1 DESIGN PARAMETERS FOR THE CALVERT CLIFFS ISFSI 1.2-3 1.2-2 PRIMARY DESIGN PARAMETERS FOR THE DSC TRANSFER SYSTEM 1.2-4 1.3-1 MAJOR SYSTEMS, SUBSYSTEMS, AND COMPONENTS OF THE CALVERT CLIFFS ISFSI 1.3-8 1.5-1 SECTION REFERENCE FOR NUHOMS TOPICAL REPORTS 1.5-2

CHAPTER 1 INTRODUCTION AND GENERAL DESCRIPTION OF INSTALLATION LIST OF FIGURES FIGURE CALVERT CLIFFS ISFSI USAR 1-iii Rev. 15 1.1-1 CALVERT CLIFFS SITE PLAN 1.2-1 GENERAL LOCATION 1.3-1 NUHOMS-24P DRY SHIELDED CANISTER ASSEMBLY COMPONENTS 1.3-2 NUHOMS ON-SITE TRANSFER CASK 1.3-3 NUHOMS TRANSFER TRAILER 1.3-4 NUHOMS CASK SUPPORT SKID 1.3-5 NUHOMS HYDRAULIC RAM SYSTEM 1.3-6 Deleted 1.3-7 NUHOMS-32P DRY SHIELDED CANISTER BASKET ASSEMBLY COMPONENTS

CHAPTER 1 INTRODUCTION AND GENERAL DESCRIPTION OF INSTALLATION LIST OF ACRONYMS CALVERT CLIFFS ISFSI USAR 1-iv Rev. 22 BGE Baltimore Gas and Electric Company CCNPP Calvert Cliffs Nuclear Power Plant DSC Dry Shielded Canister HSM Horizontal Storage Module HSM-HB High Burnup Horizontal Storage Module ISFSI Independent Spent Fuel Storage Installation NUHOMS Nutech Horizontal Modular Storage

CALVERT CLIFFS ISFSI USAR 1.1-1 Rev. 22

1.0 INTRODUCTION

AND GENERAL DESCRIPTION OF INSTALLATION

1.1 INTRODUCTION

Baltimore Gas and Electric Company (BGE) began commercial operation of the Calvert Cliffs Nuclear Power Plant (CCNPP), Units 1 and 2 on May 8, 1975 and April 1, 1977, respectively. Since then, these two 2700 MWT units have generated millions of KWH in a safe and reliable manner. In so doing, these units have discharged more than 1350 spent fuel assemblies.

These assemblies are currently stored in a common storage pool. The need to provide additional on-site storage facilities to permit continued operation is discussed in Chapters 9, 10, and 11 of the Environmental Report.

In order to provide spent fuel storage until the Department of Energy begins to accept title to spent fuel under the requirements of the Nuclear Waste Policy Act of 1982, as amended in 1987, BGE has built and will operate an Independent Spent Fuel Storage Installation (ISFSI) in compliance with Title 10 Code of Federal Regulations Part 72. Baltimore Gas and Electric Company has chosen the Nutech Horizontal Modular Storage (NUHOMS)-24P dry storage system designed by Transnuclear West (formerly Nutech Engineers, Inc.) to be used for the Calvert Cliffs ISFSI. The NUHOMS-24P system is more fully described in Reference 1.2. The location of the ISFSI on the Calvert Cliffs site is shown on Figure 1.1-1.

Calvert Cliffs Nuclear Power Plant has reanalyzed the ISFSI to use Transnuclear NUHOMS-32P Dry Shielded Canisters (DSCs) to optimize its dry spent fuel storage capacity. The NUHOMS-32P DSC system stores eight more spent fuel assemblies than the NUHOMS-24P DSC using the same external and internal shell dimensions. The NUHOMS-32P DSC storage capacity is optimized by reducing the space between the locations of each fuel assembly and by slightly reducing the size of the storage locations.

Chapter 12 is a dedicated discussion of the use of the NUHOMS-32P DSC design at CCNPP. Unless otherwise explicitly stated the information on the NUHOMS DSCs provided throughout this Updated Safety Analysis Report is applicable to both the NUHOMS-24P DSC and the NUHOMS-32P DSC.

The major difference between the NUHOMS-32P DSC and the NUHOMS-24P DSC is the internal basket assembly. The DSC is loaded into a transfer cask for transporting to and from the horizontal storage module (HSM). The same transfer cask is used for on-site transfer of either a NUHOMS-24P DSC or a NUHOMS-32P DSC. Likewise, the same HSM design is used for the storage of either a NUHOMS-24P DSC or a NUHOMS-32P DSC, however, the latter may also be stored in a modular high burnup horizontal storage module (HSM-HB).

The NUHOMS system provides safe interim storage for irradiated fuel assemblies. The fuel assemblies are confined in a helium atmosphere by a stainless steel canister. The canister is protected and shielded by a massive concrete module. Decay heat is removed by thermal radiation, conduction, and convection from the canister to an air plenum inside the concrete module. Air flows through this inter nal plenum by natural draft convection.

The canister containing irradiated fuel assemblies is transferred from the spent fuel pool to the concrete module in a transfer cask. The cask is precisely aligned and the canister is inserted into the module by means of a hydraulic ram.

CALVERT CLIFFS ISFSI USAR 1.1-2 Rev. 23 The NUHOMS system is a totally passive installation that is designed to provide shielding and safe confinement of irradiated fuel. The DSC and HSM/HSM-HB have been designed to withstand certain accidents.

The fuel assemblies to be stored in the ISFSI are located in the Calvert Cliffs spent fuel pool and were irradiated only in the Calvert Cliffs reactors. Twenty-four fuel assemblies are stored in

each NUHOMS-24P DSC, 32 fuel assemblies are stored in each NUHOMS -32P DSC, and one DSC is stored in each concrete module. The license allows construction and operation of a total of 120 modules. These modules will be built incrementally, as needed, to match CCNPP's requirements for additional storage. The first 72 modules built were poured in place (HSM) and the remaining will be of modular construction (HSM-HB). Operation of the facility will continue for up to 20 years under the initial license and continue under license renewal as necessary until a permanent facility is available for spent fuel disposal, or for a maximum of 40 years under the renewed license period (60 years, total). As defined in Table 1.2-2 of Reference 1.2, the minimum design life of the facility is 50 years.

CALVERT CLIFFS ISFSI USAR 1.2-1 Rev. 23 1.2 GENERAL DESCRIPTION OF INSTALLATION 1.2.1 GENERAL DESCRIPTION The ISFSI provides for the horizontal dry storage of irradiated fuel assemblies in a concrete module. The principal components are a concrete HSM and a stainless steel DSC with an internal basket which holds the fuel assemblies. Each HSM contains one DSC. Each NUHOMS-24P DSC contains 24 fuel assemblies. Each NUHOMS-32P DSC contains 32 fuel assemblies.

The initial license limits spent fuel storage capacity to 1,111.68 TeU of spent fuel assemblies.

The initial phase of construction includes 72 HSMs. Additional modules can be added as required on separate foundations without impact to the preceding or subsequent modules. Analyses for structural and foundation requirements provide for constructing poured in place modules in a 2x6 array and HSM-HB modules in a 2x12 array. The layout of the ISFSI is shown on Figure 1.2-1.

In addition to these primary components, the Calvert Cliffs ISFSI also requires transfer equipment to move the DSCs from the spent fuel pool (where they are loaded with spent fuel) to the HSMs where they are stored. This transfer system consists of a transfer cask, a hydraulic ram, a truck, a trailer, and a cask skid. This transfer system interfaces with the existing Calvert Cliffs spent fuel pool, the cask handling crane, and the site layout (i.e., roads and topography).

1.2.2 PRINCIPAL

SITE CHARACTERISTICS The ISFSI is located on the CCNPP site near Lusby, MD. Baltimore Gas and Electric Company owns and operates two 2700 MWT nuclear generating units on the Calvert Cliffs site. The ISFSI is located outside the protected area, but within the owner controlled area approximately 2300' southwest of the plant (Figure 1.1-1).

1.2.3 PRINCIPAL

DESIGN CRITERIA The principal design criteria and parameters for the Calvert Cliffs ISFSI are shown in Table 1.2-1. A detailed description of the criticality safety, shielding, structural, and decay heat removal features of the storage system is presented in the following Chapters and in Reference 1.2.

Design features of the NUHOMS system important to safe operation are outlined in Reference 1.2 and USAR, Chapter 12. Changes to any of these design features will be implemented only after conducting a safety review in accordance with 10 CFR

72.48.

1.2.4 OPERATING

AND FUEL HANDLING SYSTEMS The major operating systems of the ISFSI are those required for fuel handling in the Auxiliary Building and transport of the transfer cask and DSC from the spent fuel pool to the ISFSI. The primary design parameters for these systems are listed in

Table 1.2-2. The majority of the fuel handling operations involving the transfer cask which take place in the Auxiliary Building (i.e., fuel loading, drying, trailer loading, etc.) utilize standard techniques at Calvert Cliffs for spent fuel shipment. The remaining CALVERT CLIFFS ISFSI USAR 1.2-2 Rev. 23 operations (canister seal welding, transfer cask-HSM alignment, and DSC transfer) are unique to the ISFSI.

1.2.5 SAFETY

FEATURES The principal safety features of the ISFSI are inherent in the design of the DSC and the HSM. These safety features include protection of the spent fuel from the consequences of extreme environmental phenomena, redundant DSC closure welds to ensure containment, and a range of operational design features to maintain occupational dose as low as reasonably achievable. Additional details of the safety features of the NUHOMS System are presented in Reference 1.2 and USAR, Chapter 12.

1.2.6 RADIOACTIVE

WASTE AND AUXILIARY SYSTEMS No radioactive waste is generated during normal storage operations and, because of the passive nature of the ISFSI, no auxiliary systems are required for storage. The DSC Vacuum Drying System, used during initial canister closure operations, is an

auxiliary system which pumps contaminated water from the DSC to plant processing systems or back to the spent fuel pool. It is also used to evacuate the DSC and backfill it with helium. The existing Calvert Cliffs Auxiliary Building processing systems are used to handle water and gasses which are drained and vented from the cavity of the DSC during the drying process.

CALVERT CLIFFS ISFSI USAR 1.2-3 Rev. 20 TABLE 1.2-1 DESIGN PARAMETERS FOR THE CALVERT CLIFFS ISFSI GENERAL DESIGN REQUIREMENTS Capacity (Fuel Assemblies/Canister) NUHOMS-24P DSC 24 Pressurized Water Reactor Assemblies NUHOMS-32P DSC 32 Pressurized Water Reactor Assemblies Reference Fuel Assembly Parameters:

Burnup: Max. Assembly Average 47,000 MWD/MTU (NUHOMS-24P) 52,000 MWD/MTU (NUHOMS-32P) Initial Enrichment (Maximum) 4.5 w/o U 235 Initial Uranium Content NUHOMS-24P 386 kg/Assembly (Nominal) NUHOMS-32P 400 kg/Assembly (Maximum) Decay Heat Power (Maximum) 0.66 kW/Assembly Cooling Time As Required for Decay Heat Limit Fuel Rod Array Combustion Engineering 14x14 Assembly Weight (Maximum) 1,450 lbs Maximum Assembly Envelope 8.25 inches by 8.25 inches Effective Multiplication Factor: Normal NUHOMS-24P K eff < 0.95 NUHOMS-32P K ef f < 0.95 Off-Normal NUHOMS-24P K eff < 0.98 NUHOMS-32P K ef f < 0.95 Internal DSC Atmosphere Helium 99.995% pure Ambient Temperature Range -3°F to 103°F Solar Heat Load: Maximum 127 Btu/hr-ft 2 Average 82 Btu/hr-ft 2 Maximum Dose at HSM Surface During Storage (Away from Openings) 20 mrem/hr Maximum Dose at HSM Door and Penetrations 100 mrem/hr Peak Long-Term Clad Temperature 635°F Peak Short-Term Clad Temperature 1,058°F Credit for Burnup Criticality Analysis NUHOMS-24P Based on 1.8% equivalent initial enrichment NUHOMS-32P - N/A (a) Maximum Assembly Length (Includes Radiation Growth) less than 158.0" Active Fuel Length 136.7"

(a) See Section 12.3.3.4.

CALVERT CLIFFS ISFSI USAR 1.2-4 Rev. 15 TABLE 1.2-2 PRIMARY DESIGN PARAMETERS FOR THE DSC TRANSFER SYSTEM [References 1.4, 1.7, and 1.8]

SYSTEM PARAMETER VALUE Transfer Cask Nominal Cavity Diameter 68" Nominal Cavity Length 173.5" Payload 95,000 lbs (Maximum) Decay Heat Rejection (Maximum) 21.12 kW (0.66 kW/Assembly) (NUHOMS-32P DSC) Shielding (Surface Dose, Combined Neutron and Gamma, Away from Penetrations) 200 mrem/hr (Maximum)

Transfer Cask Handling Liftable by Yoke Using Crane Rotates on Lower Trunnions Vertical to Horizontal when Lowered by Crane 109.25 tons Gross Lift (Maximum) Transfer Cask Skid Payload 215,000 lbs (Maximum) Transfer Trailer Payload (Cask + Skid) 240,000 lbs (Maximum)

Dead Weight 40,000 lbs (Maximum) Gross Vehicle Weight 280,000 lbs (Maximum) Limiting Cask Height 80" (Maximum)

CALVERT CLIFFS ISFSI USAR 1.3-1 Rev. 22 1.3 GENERAL SYSTEMS DESCRIPTIONS The following subsections briefly describe the principal systems and components and their operation. The major systems, subsystems, and components of the Calvert Cliffs ISFSI are shown in Table 1.3-1. 1.3.1 SYSTEMS DESCRIPTIONS The components of storage at the ISFSI are the DSC and the HSM/HSM-HB. Additional systems required for the DSC closure and transfer include the transfer cask, the skid and skid positioning system, the trailer, the hydraulic ram system, and the DSC vacuum drying system.

1.3.1.1 Dry Shielded Canister Design 1.3.1.1.1 NUHOMS-24P DSC The design of the generic NUHOMS-24P DSC is described in detail in Reference 1.2. The Calvert Cliffs DSC is very similar to the referenced design with revisions as necessary to accommodate a slightly different fuel assembly design. The main component of construction of the DSC is a stainless

steel cylindrical containment vessel.

The component subassemblies of the NUHOMS-24P DSC

are listed in Table 1.3-1 and shown on Figure 1.3-1. The internal basket assembly is comprised of 24 guide sleeves supported by spacer disks at intervals corresponding, for the most part, to the fuel assembly spacer grids. For a few of the fuel assemblies, the spacer grids were found not to be in complete alignment with the NUHOMS-24P DSC spacer disks. Such misalignments were evaluated structurally, and found to be able to withstand normal and cask drop loads.

Support rods maintain the spacer disk location. All canister structural components are fabricated from type 304 stainless steel, except the spacer disks and support rods may be fabricated from aluminum coated carbon steel. Lead gamma shielding is used in both the top and bottom end shield plugs.

The principal differences between the Calvert Cliffs NUHOMS-24P DSC and the generic DSC design are: the addition of one spacer disk for a total of nine to accommodate the Calvert Cliffs fuel which has nine spacer grids; thinner

spacer disks with wider ligaments; an additional 1/2" of lead in both shield plugs; and a shorter overall length accounting for the shorter fuel assembly design.

Criticality safety for the NUHOMS-24P DSC, during wet

loading operations, is maintained through the geometric separation of the fuel assemblies within the internal basket assembly, the inherent neutron absorption capability of the stainless steel guide sleeves, and the proper selection of sufficiently depleted fuel assemblies. The NUHOMS-24P DSC has only been analyzed for storage in the HSM.

CALVERT CLIFFS ISFSI USAR 1.3-2 Rev. 22 1.3.1.1.2 NUHOMS-32P DSC The NUHOMS-32P DSC design increases the number of stainless steel guide sleeves to 32 (one for each spent fuel assembly) and uses an egg-crate design made of stainless steel and aluminum (borated and unborated plates) to support the guide sleeves. This egg-crate design is similar to the Transnuclear TN-68 basket assembly currently in use at a number of nuclear plants. Both the guide sleeves and the egg-crate components run the full length of the DSC cavity. This allows the guide sleeves to be in contact with the egg-crate components over the whole length of the DSC cavity versus only at spacer discs in the NUHOMS-24P DSC design. As with the NUHOMS-24P DSC design, the basket assembly is not attached to the DSC shell walls or cover plates.

Other differences are the relocation of the vent and siphon ports. They have been moved from the DSC shell wall (in NUHOMS-24P DSC) to the DSC top shield plug (in NUHOMS-32P DSC) to improve the welding, blowdown, and vacuum drying operations. The NUHOMS-32P DSC lifting fixture device is different than the lifting eyes of the NUHOMS-24P DSC (Reference 1.9). The top shield plug for the NUHOMS-32P DSC is different than the NUHOMS-24P DSC top shield plug. The design change to the top shield plug involves a reduction in the lead shield thickness, and an increase in the outer steel plate thicknesses.

Criticality Safety for the NUHOMS-32P DSC is maintained through fixed neutron absorbers in the NUHOMS-32P basket and increasing the soluble boron in the spent fuel pool water to a concentration of 2,450 ppm.

All the major steps for loading and unloading a DSC (welding, vacuum drying, etc.) are the same for the NUHOMS-24P DSC and the NUHOMS-32P DSC systems. The DSC is loaded into a transfer cask for transporting to and from the HSM/HSM-HB. The NUHOMS-32P DSC may be stored in either the HSM or HSM-HB.

1.3.1.2 Horizontal Storage Module The Calvert Cliffs ISFSI employs poured in place HSMs constructed in units of 12 configured in a 2x6 array for the first 72 modules, and modular construction HSM-HBs configured in 2x12 arrays for the remaining modules. 1.3.1.2.1 HSM Modules The HSM major design features are similar to the design presented in Reference 1.2. Major design features include items such as the overall module layout, size, wall CALVERT CLIFFS ISFSI USAR 1.3-3 Rev. 22 thicknesses, DSC support rails layout and location, and air inlet and outlet configurations and sizes. There are differences in the HSM design details compared to those presented in Reference 1.2, including the following:

A. The DSC rail support beam at the front of the module in the Reference 1.2 design was eliminated for simplification of the rail support scheme. The front end of the rails were changed to be supported directly by the front wall of the module using anchored angles similar to those used to support the rail support beams

at the middle and rear of the module. B. The amount of shear reinforcement was changed to be consistent with the specific design parameters applicable to the Calvert Cliffs ISFSI HSMs. C. The foundation size was reduced to simplify construction. D. The DSC seismic restraint was redesigned to make it significantly lighter than the Reference 1.2 design and therefore easier to handle. This reduces personal radiation exposure for placement of the restraint in the module after insertion of the DSC.

E. The DSC support rails were redesigned from WT 6x115 to WF 8x40 to employ a more efficient section which reduces weight, resulting in reduced material and construction costs. F. The DSC support assembly cross-member section was redesigned from W 10x68 to W 8x48 to employ a more efficient, lighter weight section. G. The module rebar design was revised to eliminate unnecessary rebar. H. The HSM door design was revised to incorporate additional radiological shielding material.

The HSMs are constructed in place at the ISFSI with pairs of 2x6 arrays placed end to end. The arrangement of the HSMs at the ISFSI is shown in Figure 1.2-1. Each array of 12 HSMs is constructed on a common reinforced concrete foundation slab. The HSM is designed to provide neutron and gamma shielding to achieve a nominal 20 mrem/hr contact dose rate.

Nominal contact dose rates at the HSM access door and vents are designed to be less than 100 mrem/hr.

Three foot thick end walls provide shielding on the sides of each HSM array. The front walls of the HSMs are thickened to 3-1/2. Two foot thick interior common walls provide shielding between modules to prevent scatter in adjacent modules during DSC loading and retrieval. The roof slab for CALVERT CLIFFS ISFSI USAR 1.3-4 Rev. 22 the HSMs is 3 thick. An internal slab and roof caps are provided to shield the ventilation inlet and outlet openings.

The HSMs are independent, passive systems for the dry storage of irradiated fuel assemblies. Therefore, the HSMs are designed to ensure that normal operation and credible hazards do not impair their function. To this end, the HSMs are designed to withstand the following loads:

A. Winds and Tornado (including missile impact) Regulatory Guide 1.76 B. Seismic CCNPP Updated Final Safety Analysis Report, Section 2.6 C. Flood CCNPP Updated Final Safety Analysis Report, Section 2.5 D. Snow and Ice American National Standards Institute A58.1-1982 E. Combined Loads (dead weight, live loads, thermal loads, creep effects) American Concrete Institute 349-85.

1.3.1.2.2 HSM-HB Modules The HSM-HB to be used at CCNPP is a modified version of the HSM-H described in the Updated Final Safety Analysis Report for the Standardized NUHOMS and the NUHOMS HD systems (References 1.10 and 1.11). For CCNPP, the door and the spacer are modified to accommodate the diameter and length of the 32P DSC. While the HSM-HB module design is similar to the design of the poured inplace HSM, the following is a summary of the design differences which provide improved heat rejection and shielding capabilities:

• Use of a thicker roof (38 vs 3) provides improved shielding,

• Door is inset in HSM-HB opening, with increased thickness to provide improved shielding,

• Use of slotted plates and holes in the DSC support rails to increase airflow at the bottom portion of canister,

• Increased dose rates near inlet vent; decreased in all other analyzed locations,

• Increased height of the module to increase module cavity and stack height and to minimize air flow resistance in the module cavity,

• Optimized DSC support structure minimizes airflow resistance,

• Outlet vents repositioned from top front and back to top sides (opening shared by adjacent modules),

CALVERT CLIFFS ISFSI USAR 1.3-5 Rev. 22

• Inlet vents repositioned from front bottom center to front bottom sides (opening shared by adjacent modules). Use of operational attenuation pipes improves inlet vent shielding.

The HSM-HBs will be prefabricated and assembled at the Calvert Cliffs ISFSI site whereas the current HSMs were poured in place. Each prefabricated HSM-HB is comprised of a base unit and roof unit assembled together to form a single module. The DSC is supported inside the HSM-HB by the DSC support structure. The DSC support structure (rail support assembly) is comprised of two rail sections, two slotted plates and two rail support plates. The rail support assembly provides support for the DSC during storage and acts as a sliding surface during DSC insertion and retrieval. The modules sit on a reinforced concrete basemat at the ISFSI site.

Each HSM-HB is placed in contact with an adjacent HSM-HB to form a 2x12 array. The air inlet vents extend through the front on both sides of the front wall. The front wall and the rear wall of the base unit provide support for the rails and the rail extension flanges. The roof unit rests on the front, rear, and side walls of the base unit. The air outlet vents are provided in the roof unit. Similar to the current poured in place HSMs, flat panels are used as heat shields on the interior walls of the HSM-HB. The heat shields provide thermal protection for the HSM-HB concrete. Finally, attenuation pipes are added, as an option, to the inlet vent screens to improve the shielding capabilities of the module.

The HSM-HB shield door consists of a rectangular steel plate at the front attached to a circular reinforced concrete block at the rear. Both the steel plate and concrete blocks fit the circular opening in the front wall. Studs are welded to the circular steel plate which provides anchors to the rear reinforced concrete block. The concrete door provides missile protection and shielding. End shield walls are provided at the ends of a module array to provide the required missile and shielding protection.

During DSC insertion/retrieval operations, the transfer cask is docked with the HSM-HB docking surface and mechanically secured to the embedments provided in the front wall. The embedments are equally spaced on either side of the HSM-HB access opening.

Storage of the NUHOMS-32P DSC in the HSM-HB is subject to the same controls and limitations as those of the HSM.

CALVERT CLIFFS ISFSI USAR 1.3-6 Rev. 22 1.3.1.3 Transfer Cask The transfer cask used with the ISFSI provides radiological shielding during the DSC closure operations and during transfer of the DSC to the HSM/HSM-HB. To ensure structural integrity, the transfer cask also provides protection of the DSC against potential natural and operational hazards during transport and transfer of the DSC to the HSM/HSM-HB.

Both solid neutron and lead gamma shielding are incorporated into the transfer cask design. Figure 1.3-2 shows the major components of the transfer cask. The Calvert Cliffs transfer cask has a solid hydrogenous neutron shield in the outer annulus of the cask, and as a result the liquid neutron shield expansion tank of Reference 1.2 was deleted.

1.3.1.4 Transfer Trailer The transfer trailer is used to transport the transfer cask skid and the loaded transfer cask from the Auxiliary Building to the ISFSI. The transfer trailer is an industrial heavy-haul trailer with pneumatic tires, hydraulic suspension and steering, and brakes on all wheels. The approach slab has adequate space for turning the transport trailer and tow vehicle. Four hydraulic jacks are incorporated into the transfer trailer design to provide vertical elevation adjustment for alignment of the cask at the HSM. The transfer trailer is shown in Figure 1.3-3. It is pulled by a conventional tractor.

1.3.1.5 Transfer Cask Skid and Positioning System The transfer cask skid is essentially identical in design and operation to previous NUHOMS-24P system transfer cask support skids. The skid is supported on lubricated bearing plates attached to the trailer deck and can be moved horizontally on the bearing plates by the hydraulic actuators of the skid positioning system. The skid is secured to the trailer deck in a travel lock position during cask loading and transport operations. The transfer cask skid is shown in Figure 1.3-4.

1.3.1.6 Hydraulic Ram System The hydraulic ram consists of a double acting hydraulic cylinder with a capacity of 80,000 lb in either push or pull and stroke of 21'. The ram is supported during operation by a frame assembly attached to the bottom of the transfer cask and a tripod assembly resting on the concrete slab. The operational loads of the hydraulic ram are grounded through the transfer cask. The hydraulic ram system includes a grapple at the end of the piston which is used to engage a grapple ring on the DSC for retrieval operations.

Figure 1.3-5 shows the hydraulic ram system.

1.3.1.7 Vacuum Drying System The vacuum drying system removes water and air from the DSC and fills it with helium. The vacuum drying system has four operational modes:

water removal, helium or air forced water removal, vacuum pumping, and helium backfilling.

CALVERT CLIFFS ISFSI USAR 1.3-7 Rev. 22 1.3.1.8 Closure Welding System The DSC closure welds on the shield plug and the top cover plate are normally placed by a fully remote, automatic welding system. The system includes modular components and is designed for rapid setup. Welding operations are remotely controlled by an operator who views the progress of the weld through closed circuit television. The welding head is designed to permit rapid replacement with either a UT probe, or a plasma gouging torch which can be used to remove the shield plug and top cover plate closure welds. Manual welding may also be used for closure welds. The allowed duration of manual welding is limited by the ambient dose rate at the location of the welding (Reference 1.6).

1.3.1.9 System Operation See Chapter 5 for a detailed description of the Calvert Cliffs ISFSI System Operation.

CALVERT CLIFFS ISFSI USAR 1.3-8 Rev. 22 TABLE 1.3-1 MAJOR SYSTEMS, SUBSYSTEMS, AND COMPONENTS OF THE CALVERT CLIFFS ISFSI Dry Shielded Canister NUHOMS-24P DSC Basket NUHOMS-32P DSC Basket Guide Sleeves (24) Guide Sleeves (32) Spacer Disks (9) Egg-Crate Support Rods (4) Peripheral Steel Rails DSC Shell With Bottom Shield Plug DSC Shell With Bottom Shield Plug Shield Plug (Top) Shield Plug (Top) Cover Plates (Top and Bottom) Cover Plates (Top and Bottom) Siphon and Vent Ports Siphon and Vent Ports Ram Grapple Ring Ram Grapple Ring Horizontal Storage Module Reinforced Concrete Walls, Roof, Basemat, and Foundation DSC Structural Steel Support Assembly DSC Seismic Retainer Cask Docking Flange and Tie-Down Restraints Heat Shield Shielded Front Access Door and Door Supports Ventilation Air Openings (One Inlet, Two Outlets) Shielded Ventilation Air Inlet Plenum Ventilation Air Outlet Shielding Blocks Lightning Protection System Cask Lifting Yoke

Transfer Cask Cask Structural Shell Assembly Bolted Top Head Assembly Upper Lifting Trunnions Lower Tilting Trunnions Lead Gamma Shielding Solid Neutron Shielding Ram Access Penetration Cover Plate Ram Access Penetration Shield Plug Assembly Ram Mounting Frame Transfer Trailer and Skid Heavy Industrial-Grade Trailer Cask Support Skid Skid Positioning and Alignment System Hydraulic Ram System Hydraulic Cylinder Rear Tripod Support Frame Grapple Assembly Vacuum Drying System Automated Remote Closure Welding System

CALVERT CLIFFS ISFSI USAR 1.4-1 Rev. 22 1.4 IDENTIFICATION OF AGENTS AND CONTRACTORS The prime contractor for design, analysis, and component supply for the Calvert Cliffs ISFSI was Transnuclear (formerly Nutech Engineers, Inc.), of Columbia, MD. The ISFSI is owned by CCNPP, LLC and operated by Exelon Generation. Construction of the ISFSI is the responsibility of an approved construction contractor. For the poured in place HSMs, licensing support, geotechnical engineering, and Quality Assurance Program revisions were performed by Duke Engineering & Services, Inc., utilizing Duke Power Company personnel experienced on the Oconee Nuclear Station ISFSI. Subsurface investigations at the ISFSI were performed by

Law Engineering Testing Company.

Geotechnical, civil, structural, mechanical, and electrical engineering support for the installation of the HSM-HB modules was provided by Sargent & Lundy LLC and MACTEC Engineering and Consulting, Inc. (formerly Law Engineering Testing Company). Subsurface analysis for the installation of the HSM-HB modules was performed by Sargent & Lundy LLC.

CALVERT CLIFFS ISFSI USAR 1.5-1 Rev. 8 1.5 MATERIAL INCORPORATED BY REFERENCE The Topical Reports for the Nutech Horizontal Modular Storage Systems for Irradiated Nuclear Fuel, (NUH-002, Revision 1A, July 1989) Reference 1.2, and (NUH-001, Revision 1A, June 1986) Reference 1.3, are hereby incorporated into this document by reference and referred to by Section in Table 1.5-1.

CALVERT CLIFFS ISFSI USAR 1.5-2 Rev. 8 TABLE 1.5-1 SECTION REFERENCE FOR NUHOMS TOPICAL REPORTS TITLE REPORT NO.

SUBMITTAL DATE SAR SECTIONS IN WHICH REFERENCED Topical Report for the Nutech Horizontal Modular Storage System for Irradiated Nuclear Fuel, NUHOMS-24P, Nutech Engineers, Inc.

NUH-002, Revision 1A, July 1989 July 14, 1989 1.1, 1.2, 1.3, 1.5, 1.6, 3.1, 3.2, 3.3, 4.1, 4.2, 4.7, 7.1, 7.2, 7.3, 7.4, 8.1, 8.2 Topical Report for the Nutech Horizontal Modular Storage System for Irradiated Fuel, NUHOMS-07P, Nutech Engineers, Inc.

NUH-001, Revision 1A, June 1986 June 27, 1986

7.1 CALVERT

CLIFFS ISFSI USAR 1.6-1 Rev. 22

1.6 REFERENCES

1.1 Deleted

1.2 Topical Report for the Nutech Horizontal Modular Storage System for Irradiated Nuclear Fuel, NUHOMS-24P, Nutech Engineers, Inc., NUH-002, Revision 1A, July 1989 1.3 Topical Report for the Nutech Horizontal Modular Storage System for Irradiated Fuel, NUHOMS-07P, Nutech Engineers, Inc., NUH-001, Revision 1A, June 1986 1.4 Letter from Mr. G. C. Creel (BGE) to Director, Office of Nuclear Material Safety and Safeguards (NRC), dated December 20, 1990, Response to NRC's Comments on the Safety Analysis Report (SAR) for BGE's License Application for Calvert Cliffs Independent Spent Fuel Storage Installation (ISFSI)

1.6 CCNPP

Calculation CA05924, Calvert Cliffs ISFSI/NUHOMS-24P Radiation Dose Rates for Cask Loading and Transfer 1.7 CCNPP Calculation CA06297, Transfer Thermal Analysis, 103

°F Ambient 1.8 CCNPP Calculation CA06329, NUHOMS-32P - Transfer Cask Structural Analysis

1.9 CCNPP

Drawing 84227SH0001, NUHOMS-32P DSC Parts List 1.10 Transnuclear, Inc., Updated Final Safety Analysis Report for the Standardized NUHOMS Horizontal Modular Storage System for Irradiated Nuclear Fuel, NRC Docket No. 72-1004, Transnuclear Document No. NUH-003, Revision 11 1.11 Transnuclear Inc., Updated Final Safety Analysis Report for the NUHOMS HD Horizontal Modular Storage System for Irradiated Nuclear Fuel, NRC Docket No. 72-1030, Revision 2