Instrument and Service Air Flashcards
(39 cards)
What is the purpose of the Instrument Air system and is it safety related?
Not Safety Related
- Portions of the system are treated as safety-related.
- The containment isolation portion of this subsystem is safety-related.
- Safety-related control valves have nitrogen backup.
Designed to provide dry, oil-free air for instrumentation and controls.
Flow Requirements
- 80 standard cubic feet per minute (scfm) for the Nuclear Steam Supply System
- 115 scfm for the remainder of the plant.
What is the purpose of the service air system and is it safety related?
Not Safety Related
Provides unfiltered, undried air, directly from Instrument Air to Service Air hose stations and components throughout the plant.
What is the purpose of the High Pressure Air System and is it safety related?
Has Both Safety Related and Non-Safety Related Portions
Safety Related
- Provides high-pressure control air for operation of vital valves located in each of the Engineered Safeguards rooms.
- Supplied via T-9A/B
Non-Safety Related
- Provides high-pressure control air for operation of non-vital valves located in Turbine Building.
What is the purpose of the Feedwater Purity Air System and is it safety related?
Non-Safety Related
It is an independent air system providing filtered, moisture-free air to Feedwater Building components.
It also can supply filtered, dried air directly to the Instrument and Service Air system if needed. This is done using air dryer M-993 along with pre and post filters.
What is the design and capacity of the C-2 instrument air compressors?
Compressors C-2A, C-2B and C-2C
- Air cooled rotary screw type compressor
- Rated for 288 SCFM - considered full capacity
- Operating range: 95-105 psig
What are the power supplies for Compressors C-2A, C-2B and C-2C?
C-2A - LCC-11 (52-1106)
C-2C - LCC-11 (52-1107)
C-2B - LCC-12 (52-1207)
What starts an Instrument Air Compressor?
Control Room Handswitch on C-13
HAND
- 52‑1106/52-1207/52‑1107 closes
- Red light on in Control Room
OFF
- 52‑1106/52-1207/52‑1107 opens
AUTO
- Amber Light is Lit
- 52‑1106/52-1207/52‑1107 controlled by header pressure
- 92 psig on PS-1213 starts compressor
- Compressor will load after 7 seconds if pressure <95 psig
How long after the red light is lit in the control before the compressor can assume loading?
7-10 seconds
Startup checks for the microprocessor
If an Instrument Air Compressor is running more than 10 minutes unloaded, what happens?
Compressor goes to “sleep”
- Compressor motor shuts down
- Local digital display reads “READY TO START”
- Breaker stays closed and handswitch indication in the Control Room will continue to have a red light on.
- Compressor will restart when discharge pressure is sensed to be less than 95 psig
- There is no alarm for this condition
What trips an instrument air compressor?
Breaker trips (overcurrent or low voltage on bus 1C)
Load shed due on a Loss of Offsite Power (LOOP).
Compressor shutdown initiated by microprocessor due to various ALARM conditions
- Includes low oil pressure, and Emergency Stop (local pushbutton) for example.
- Breaker is NOT tripped
What powers the ventillation for the instrument air compressors?
MCC-3 powers Control panel C-1034 which powers V‑201A/B/C.
V-201 A/B/C individual handswitch in manual - runs, auto - runs if compressor running.
What is the cooling medium for the instrument air compressor aftercoolers?
A is cooled by ‘B’ Critical Service Water
B is cooled by non-critical service water
C is cooled by ‘A’ Critical Service Water
What is the capacity of T-8A/B/C?
- Design Pressure: 125 psig
- Capacity: 57 Cubic feet each
- Normal operating range: 95-105 psig.
How are instrument air pre and post filters aligned and what is their max dp?
1 of each aligned for service
4 psid max
What is the function of CV-1211 “Penet. MZ-65 Instrument Air Cont. Isolation”?
CHP/CHR do NOT impact.
- Isolates Instrument Air from Containment Instrument Air
- Normally open. Air to Open.
- Operated by hand switch in the Control Room.
- No automatic functions associated with CV‑1211.
- Fails open on loss of air or loss of power (DC Bus D-11) to operating solenoid.
- Nitrogen Backup from N2 Station 5 to allow closure in case of loss of operating air.
What is the function of CV-1212 “Service Air Header Isolation”?
- Isolates Instrument Air header from the Service Air header.
- Normally open, air to open
- No Control Room Handswitch
- Auto closes on low Instrument Air header pressure.
- PS-1210 - Sensed downstream of the After- filters F-5A/F-5B
- Setpoint: 85 psig
- Fails closed on loss of air
- Fails closed on loss of power (DC Bus D-11) to operating solenoid.
What is the function of CV-1221 “Service/Inst Air Tie in from FWP Bldg?”
- Isolates Instrument Air header and the Feedwater Purity Building Air header
- Normally closed air to CLOSE
- No automatic functions associated with CV‑1221.Operated by hand switch in the Control Room.
- Fails OPEN on loss of air
- Fails OPEN on loss of power (DC Bus D-11) to solenoid.
What is the capacity of the high pressure air compressors?
- High Pressure, oil lubricated air compressors.
- External after cooler (medium is non-forced air), desiccant dryer and receiver tank.
- 22.3 scfm @ 325 psig
- NOP: 310–325 psig
What are the power supplies for the HP air compressors?
C-6A – MCC-8 (Bus 1D)
C-6B – MCC-7 (Bus 1C)
C-6C – MCC-4 (Bus 1E)
What is the design of the high pressure air receiver tanks?
57.7 ft3 @ 350 psig
Design basis of tank allows all valves it supplies to be stroked twice at a starting pressure of 260 psig assuming no compressor running.
Must be >= 260 psig in Modes 1 and 2 or Mode 3 with temp >325F.
What is the restriction on T-9A operations?
T-9A less than 260 psig in Mode 1, 2, or 3 (greater than or equal to 325°F),
- Tank is Inoperable.
- The instrument air and N2 supply valves to all CVs supplied by the inoperable tank shall be checked to ensure correct alignment.
- Refer to P&ID M-225, Sh 1 and/or SOP-3, Attachment 10, “Checklist CL 3.1, Engineered Safeguards System Checklist (Shutdown Cooling In Service).”
- Technical Specifications LCO 3.5.2 should be reviewed for LCO requirements
What is the restriction on T-9B operations?
T-9B provides the minimum air supply required for operability of CV-3027 and CV-3056.
IF T-9B pressure lowers to less than 260 psig in Mode 1, 2, or 3 (greater than or equal to 325°F), THEN DECLARE T-9B inoperable AND ENTER LCO 3.0.3.
Is tank 9-C safety related and when can it be cross-tied?
Not Safety Related
Can be crosstied to either T-9A or T-9B in any mode, but not both at the same time.
What is the design and capacity of the feedwater purity air compressors?
- Two stage reciprocating, oil lubricated.
- Internal Inner-Cooler, external After-Cooler and Receiver Tank
- 876 scfm @ 125 psig
- Normally only use 50 to 100 scfm
- NOP: 95-110 psig
