ML21278A210
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9.10 COMPRESSED AIR SYSTEM 9.10.1 DESIGN BASIS The Compressed Air System consists of the instrument air and plant air subsystems. The instrument air subsystem is designed to provide a reliable supply of dry and oil-free air for the pneumatic instruments and controls and pne umatically operated containment isolation valves. The plant air subsystem is designed to meet necessary service air requirements for plant maintenance and operation. The designs of each subsystem are based on an estimated instrument air requirement of 260 scfm and an estimated plant air requirement of 600 scfm. The instrument air subsystem compressor is sized for 450 scfm.
9.10.2 SYSTEM DESCRIPTION The Compressed Air System is shown schematically on Figures 9-23 (Unit 1) and 9-28 (Unit 2). The Plant Water and Air Service System is shown in Figure 9-29.
The system incorporates two full-capacity, non-lubricated compressors for instrument air, each having a separate inlet filter aftercooler and moisture separator. The instrument air compressors then discharge to a single header which is connected to two air receivers.
Both air receivers discharge to a compressed air outlet header which supplies instrument air to the air dryers and filter assembly. The compressed air header then divides into branch lines supplying the pretreatment and tank storage area, the Intake Structure, the service building, the water treatment area, the Turbine Building, the containment structure, and the Auxiliary Building.
An emergency back-up tie from the plant ai r header has been provided to automatically supply air to the instrument air system if the pressure to the instrument filter and dryer assembly falls below a preset value. Local controls are provided to prevent plant air use when this occurs. For the transition from normal to emergency service, air storage tanks provide an approximate 20-minute supply (Table 9-21).
Particle size, dew point, and oil hydrocarbons are controlled for instrument air supply in accordance with Instrument Society of America standards. Additionally, the Calvert Cliffs approach to controlling air quality was submitted to the NRC in response to Generic Letter 88-14.
One full-capacity plant air compressor with an inlet filter, and integral air coolers and moisture separators, discharges to the plant air receiver. The receiver outlet header is connected to the prefilter assembly, which is followed by an outlet header branching into two separate air headers, one to the instrument air dryers and filter assembly, and the other to the plant air pretreatment and storage tank area, the Intake Structure, the service building, the water treatment area, the Turbine Building, the Containment Structure, and the Auxiliary Building. A system cross-tie between Unit 1 and Unit 2 has been provided for the plant air headers. Additionally, each plant air system has a permanent connection for the installation of a portable air compressor to allow for maintenance of the compressors or SRW system during Modes 3, 4, 5, 6 and defueled. This connection may also be used in Modes 1 and 2 to provide a contingency backup to an operating plant air compressor should the other installed plant air compressor be unavailable.
9.10.3 SYSTEM COMPONENTS Ratings and construction of system components are listed in Table 9-21.
9.10.4 SYSTEM OPERATION A continuous supply of instrument air is provided to hold various pneumatically-operated valve actuators in the positions necessary for operating conditions. Normally, the plant air
CALVERT CLIFFS UFSAR 9.10-1 Rev. 47 compressor and one instrument air compressor will operate and the second instrument air compressor will be on automatic standby.
9.10.5 SYSTEM RELIABILITY The power supply for the normal compressors is the normal distribution system and can be backed up by the EDG. Additional emergency air compressors, known as the saltwater air compressors (SWACs), provide redundant air supply to most safety-related components when the normal air compressors are lost. The SWACs (Table 9-16B) are seismically qualified, air-cooled, and oil-free. The instrument air portion of the compressed air system is primarily used for va lve actuation and is not used in any reactor indication, control, or protective circuitry. These valve actuators are designed to fail in the safe position after loss of the instrument air supply. The design of the system and installed equipment redundancy ensure that total loss of instrument air supply is highly improbable. Concurrently, attention has been gi ven to ensure that valve failures from loss of instrument air supply are consistent with the capability to maintain the plant in a safe condition and mitigate the consequences of any simultaneous incident or accident.
9.10.6 TESTS AND INSPECTIONS Each component is inspected and cleaned prior to installation into the system.
Instruments were calibrated during testing and automatic controls were tested for actuation at the proper setpoints. Alarm functions were checked for operability and limits during plant operational testing. The systems were operated and tested initially with regard to flow paths, flow capacity, and mechanical operability.
CALVERT CLIFFS UFSAR 9.10-2 Rev. 47 TABLE 9-21 COMPRESSED AIR SYSTEM COMPONENT DESCRIPTION A. INSTRUMENT AIR SYSTEM Air Compressor Type Vertical, non-lubricated reciprocating, two state Y-angle type Quantity 2 (per unit)
Design capacity (scfm) 470 (each)
Discharge pressure (psig) 100 Motor 100 hp, 3 phase, 60 Hz, 460 Volt Code ASME Section VIII, NEMA Intake Filter - Silencer Type dry Quantity 2 per Unit Base size 8" Aftercooler and Moisture Separator Type Shell and tube Quantity 2 (1 per compressor)
Code TEMA Class C, ASME Section VIII Air Receiver Type Vertical Quantity 2 (1 per compressor)
Design pressure (psig) 115 Actual volume (ft3) 96 Code ASME Section VIII Prefilters Type Cartridge Quantity 2 per Unit Capacity (scfm) 720 Filtration 99% removal of all liquids, oil, and water droplets Air Dryer Type Heatless Desiccant Activated alumina absorbent Quantity 2 per unit Capacity (scfm) 475 (Nos. 12 and 22),
700 (Nos. 11 and 21)
Outlet moisture content with saturated air -40°F dew point at 100 psig inlet Afterfilters Type Cartridge Quantity 2 per Unit Capacity (scfm) 600 Filtration 100% removal of all particulates over 0.9 microns
CALVERT CLIFFS UFSAR 9.10-3 Rev. 47 TABLE 9-21 COMPRESSED AIR SYSTEM COMPONENT DESCRIPTION Piping and Valves Valves 150 psi ANSI for 2-1/2" and larger, 600 psi ANSI for 2" and smaller Piping Seamless ASTM A106, Grade B (2-1/2" through 24")
Code ANSI B31.1 (ANSI B31.7 - penetration piping)
B. PLANT AIR SYSTEM Air Compressor Type Centrifugal, two stage, with integral air coolers and moisture separators Quantity One per Unit Design capacity (scfm) 600 Discharge pressure (psig) 100 Motor 200 hp, 3 phase, 60 Hz, 460 Volt Code NEMA Intake Filter Silencer Type Dry Quantity One per Unit Air Receiver Type Vertical Quantity 1 Design pressure (psig) 115 Actual volume (ft3) 96 Code ASME Section VIII Prefilter Type Cartridge Quantity 2 per Unit Capacity (scfm) 720 Filtration 99% removal of all liquids, oil, and water droplets Piping and Valving Valves 150 psi ANSI for 2-1/2" and larger, 600 psi ANSI for 2" and smaller Piping Seamless ASTM A106, Grade B (2-1/2" through 24")
Code ANSI B31.1 (ANSI B31.7 - penetration piping)
C. INSTRUMENT BACKUP AIR SYSTEM Storage Tank Type Vertical Quantity 4 Capacity 300 ft3 Design pressure (psig) 225 Code ASME Section VIII Air Amplifier Ratio 2:1
CALVERT CLIFFS UFSAR 9.10-4 Rev. 47