Systems Exam 6 - Uncontrolled Access Ventilation Systems Flashcards
(26 cards)
Why must safety-related battery temperatures be maintained >70°F?
Battery capacity decreases in colder temperatures <70°F, and batteries may no longer be capable of performing their designated safety function.
UPS A/C Unit Auto Start
Auto Starts:
→SIS step 9 (≈80 secs)
→BOS step 10 (≈80 secs)
→Hi Temp >104°F any UPS distribution rm w/no lockouts
Other Info:
→local handswitch must be in Remote and CR handswitch in Auto for auto starts to work
→Operator Lockouts prevent starting remotely with SI or BO present
→loss of power will start UPS HVAC units thinking temp is >104°F
→units powered from XEB3-2 (X-01) & XEB4-2 (X-02)
Office and Service Area Ventilation INTERLOCKS
Supply and recirculation fan supply breakers are shunt tripped in the event of a SI on either unit.
They require local operator action to close the breakers in order to allow components to restart.
What does Uncontrolled Access Ventilation encompass?
→UPS HVAC
→Uncontrolled Access area ventilation
→ECB Ventilation
→Battery Exhaust Ventilation
→Office and Service Area HVAC
→Turbine Bldg HVAC
→Turbine Bldg Switchgear HVAC
→Turbine Bldg Supply and Exhaust
→TVR Room HVAC
→MFP Speed Controller Room HVAC
→Turbine Bldg Stairway Pressurization fans
→Switchyard Relay Houses HVAC
→SWIS Ventilation
→Miscellaneous HVAC
→Chlorination Bldg HVAC
→Storage Tank room heaters
→PAP and AAP HVAC
→tornado venting scheme
Tornado Venting Scheme
→designed to maintain the structural integrity and safety functions of plant buildings and components during tornado conditions
→designed to function in a Design Basis Tornado with a storm front rotational velocity of 300 mph that is moving over the ground at 60 mph
→postulated tornado could drop local atmospheric pressure 3 psi and rate of 1 psi/sec
→pressure relief dampers required to open in either direction when D/P across dampers reaches 3 inches water gauge (INWG) pressure (interior dampers) and 7.5 INWG (exterior dampers)
Service Water Intake Structure (SWIS) Ventilation
→designed to maintain SWIS temp >40°F in winter and <122°F during summer
→outside air drawn in through grated openings near water intakes
→air picks up heat from operating equipment
→8 wall mounted exhaust fans - 2 per associated SSW pump, air exits through gravity dampers
→fans auto start at 74°F; stop at 70°F
→1 exhaust fan for diesel fire pump room; runs continuously; auto functions defeated
→ TRM 13.7.36 Area Temperature Monitoring - max temp limit for SWIS is 127°F for normal conditions and 131°F for abnormal conditions
Office and Service Area HVAC
→restrooms, janitor closet and other small areas exhausted by Toilet Exhaust fans; the rest exhausted by Primary Plant Ventilation
→shunt trips on SI
→breaker must be closed locally following SI reset
UPS HVAC consists of…
→Emergency Fan Coil Units (1 per UPS room); must be operating to be considered operable
→UPS A/C Units (1 per train, X-01 Tr A, X-02 Tr B)
→purpose is to maintain UPS and Battery Room temps <104°Fduring normal conditions and <113°F for abnormal conditions
UPS Emergency Fan Coil Units
→1 per UPS room, normally energized (on/off local controls only)
→cooled by Safety Chill Water
→no auto features, but if running before loss of power, will restart once power restored
→Train A powered from uEB3-1
→Train B powered from uEB4-1
→EFCU operations is assumed in Station Blackout Analysis
UPS A/C Units
→normally in standby
→X-01 Unit (Train A) provided to cool Train A both units; X-02 for Train B both units, but either train can cool both units/trains
→cooling water supplied by Safeguards CCW
→X-01 powered from XEB3-2
→X-02 powered from XEB4-2
→Hi Temp alarm relays supplied from XC3-1, BOP Aux Relay Rack 8
UPS A/C Unit Refrigeration Loop
→time delay relay (anti-recycle 5 mins after previous stop)
→compressor space and crankcase heaters turn on 5 minutes after compressor turns off; turn off when compressor is on
Turbine Building Ventilation Purpose & Subsystems
Purpose:
→dissipates heat generated by operating equipment
→provides freeze protection to Turbine Bldg systems and components during cold weather periods
Subsystems:
→Turbine Bldg Supply and Exhaust
→Turbine Bldg Switchgear HVAC
→TVR Room Air Conditioning
→Digital Control Room Air Conditioning (MFP Speed Control Room)
→Turbine Bldg Stairwell Pressurization Fans
→DC Emergency Lighting Battery Room A/C
Turbine Building Supply and Exhaust
→all power supplies are non-1E
→no automatic actions
→malfunctions are annunciated in the CR
→Hi Temp alarm in TVR Room 95°F
What is the purpose of the Turbine Building Stairwell Pressurization Fans?
→create positive pressure in the Turbine Building stairwells to provide a smoke free egress path in case of fire
The DC Emergency Lighting Battery Room A/C unit is interlocked with…
…the room exhaust fan.
TR 13.7.36 Area Temperature Monitoring
What are the normal and abnormal temperature limits for UPS/Battery Rooms, Chiller Equipment Rooms, and the SWIS?
Uncontrolled Access Ventilation Purpose/Design Basis
Purpose/Design:
→provides ventilation to the non-Class 1E battery rooms during all modes of operation except Safety Injection
→provides heating and cooling to the affected rooms to maintain temperature ≤104°F in the summer and ≥40°F in the winter
→maintains battery rooms ≥70°F during normal operations in the winter and between 70°F and 120°F during emergency plant operation
→provides isolation for a High Energy Line Break (HELB) in the Instrument Air Compressor and Air Dryer Area
→supplies Unit 1 and Unit 2 battery rooms, cable spreading rooms, and other miscellaneous spaces in the uncontrolled access area of the ECB
→maintains Battery Room H2 concentration within required acceptable levels (≤4%)
Uncontrolled Access Ventilation Components
→ECB AHU (roll filter, heater, cooling coil)
→2 ECB Supply Fans (cooling water supplied from Vent Chill Water)
→2 ECB Exhaust Fans
→12 (6 per Unit) Battery Room Fans
→8 fans (4 per unit) are Safety Related, 7-10)
→#8 fans in both units are normally supplied from 1E 480 VAC, but can be supplied from outage power
→4 Train C Battery Charger Room Fans
→all fans controlled from MCR
ECB / Uncontrolled Access Ventilation System Interlocks
→ECB Supply Fans trip if damper closed, time delayed relay
→ECB Exhaust Fans Auto start when either Supply Fan is started
→ECB Exhaust Fans trip when Supply Fans are not running
→ECB Supply and Exhaust Fans trip on a fire signal (Detector or Halon Actuation) from either unit CSR
→IAC Room and Chemical Feed Room have pressure sensitive isolation dampers that isolate on high pressure
→ following an SI (15 sec) or BO (0 sec) 1E battery Rooms exhaust fans (7-10) will Auto Start
→Fans 7-10 Auto Start on low D/P and placing them both (7 & 8 or 9 & 10) in pullout alarms on SSII
→ Train C Battery Exhaust Fans (11 and 12) will auto start following a BO; will also trip on SI, but will START automatically on low fan D/P after SIS reset
→Ventilation System limits the H2 concentration in the safety related battery rooms under all operating conditions and the non-Class 1E battery rooms during all operating conditions except Safety Injection
ECB Ventilation Supply Damper
→HV‐5925 mechanical stop provides minimum flow (≈15,000cfm min)
→air to open, fails closed
→controlled by recirc damper position
→closes when recirc damper full open
→opens when recirc damper is not full open
ECB Ventilation Supply Fans
→manual start
→auto stops:
→both supply and recirc dampers are still closed for 10 seconds after a start signal
→fire signal in cable spreading room from either unit
→Fan 31 powered from XB3‐1
→Fan 32 powered from XB3‐1
ECB Exhaust Fans
→both exhaust fans start when either supply fan starts
→trips on both supply fans not running OR fire signal from either Cable Spread Room
ECB Exhaust & Recirc Dampers
ECB Exhaust Damper:
→fails closed
→interlocked with recirc damper
→opens when recirc damper not full open
ECB Recirc Damper:
→fails open
→auto opens when intake air <55°F or >75°F
→open limit switch closes supply and exhaust dampers
Battery Room Exhaust Isolation Damper
→fails open
→interlocked with fan start/stop
→damper not being open within 10 seconds of fan start closes damper and trips fan
→to reset, damper must be opened following issue resolution and fan hand switch must be taken to Stop
