Term
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Definition
1.The Auxiliary Building Ventilation System (ABV) is a once through heating and ventilation system supplemented by individual room coolers. The system is required to operate continuously in all modes in order to:
nProvide satisfactory air temperature to Mechanical Areas
nMaintain Aux. Bldg pressure slightly negative with respect to atmosphere
nDirect airflow from clean to potentially contaminated areas
nControl release of particulate and gas to 10CFR20 limits
nPurge Containment as needed in modes 5 and 6.
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Term
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Definition
1.Total Capacity of system is based on summertime operation with the following flows:
a)48,000 cfm Normal Building Ventilation
AND
b)35,000 cfm containment purge flow
2.Maintain Aux Bldg average temperature 60-110oF with corresponding outside temperatures of 0-95oF
3.Heating water coils sized to provide 60oF to Auxiliary building and no less than 45oF air to Containment in winter.
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Term
| Design Basis Safety Related Room Coolers |
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Definition
4.Safety Related Room Coolers in conjunction with once through ventilation air are designed to limit ambient temperature in the vital pump rooms to the following:
a)Positive Displacement Charging Pump – 110oF
b)Containment Spray Pumps – 115oF
c)RHR, CC, AFW, Cent Chg Pumps, and SI pumps – 120oF
Note: These temperatures assure long-term and reliable operation of equipment and accessibility to this equipment for maintenance.
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Term
| Normal compliment of Fans for ABVS: |
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Definition
1 Supply fan
2 Exhaust fans
Note: Exhaust fans must be able to pull a negative pressure. |
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Term
DETAILED DESCRIPTION – SUPPLY FANS |
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Definition
Belt Driven centrifugal fan rated at 55,000 cfm
Power Supply:
§11/21 Fan Powered from “C” 460V Vital Bus
§12/22 Fan Powered from “B” 460V Vital Bus
Auto Start/Trips
§SEC – 5 second trip (Modes II, III, IV)
§Motor Overload
Normal Operation
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21 fan in-service with 22 fan “Blocked" from RP2
blocked fans suction is open
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Term
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Definition
§The Aux Building Exhaust subsystem consists of three 50% capacity fans and four filter units: three Roughing plus HEPA units (21-23) and one charcoal unit (24), along with an exhaust duct system.
§Two fans are normally I/S.
§There are three exhaust headers: East and West “Emergency” and “Normal.” The Emergency header does not connect to 23 HEPA because 23 HEPA does not exhaust to the Charcoal Filter.
§Normally “HEPA 23 ONLY” or “HEPA 22 ONLY” is selected for “NORMAL AREAS” and “HEPA 21” or “HEPA 22 ONLY” for “EMERGENCY AREAS” by NCO (S2.OP-SO.ABV-0001, 5.3).
§Fiberglass Roughing Filters remove 38% of exhaust particulates.
§HEPA Filters remove at least 99.97% of particles > 0.30 microns
§Charcoal Filter adsorbs a minimum of 90% elemental and methyl iodine.
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Term
CHARCOAL FILTER (24 UNIT) |
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Definition
§Charcoal Filter is a standby Unit used during emergency situations or when radiation monitoring indicates the need
§Operates in conjunction with either 21 or 22 HEPA Units.
§Charcoal Filter is only rated at 24,000 cfm (same rating as 21 HEPA) therefore if during Mode 1-4 the 22 HEPA is aligned from the NORMAL areas or PURGE to the charcoal filter, the Charcoal unit is considered inoperable.
•
If 22 is aligned to the EMERGENCY areas and to the Charcoal Unit the system is operable since the EMERGENCY area flow rates are less than 24,000 cfm.
§Local manometer provides indication of pressure drop across filter
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Term
| Adjustable Inlet guide vanes.... |
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Definition
(ABV17 & 18) are controlled by a temperature device on the Exhaust plenum
§Exhaust Temperature > 80oF - vanes go full open
§Exhaust Temperature < 70oF - vanes go to 66% open
§Fail Open on loss of Air or Power or Block Switch in “Block”
Each fan has a gravity operated backdraft damper on its discharge
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Term
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Definition
60 HP induction motor operated, belt driven, centrifugal fans
460V A, B, C power
Take suction from plenum
Discharge to Plant Vent
35,000 scfm capacity
AUTO START/TRIPS:
1) SEC - 5 Second load strip in Modes II, III, IV
2) Motor overload
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Term
| ABV Exhaust Inlet Guide Vanes |
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Definition
Inlet Guide Vanes (ABV14) control Aux Building pressure.
When Aux Building pressure becomes more negative than 0.10 in w.g. with respect to atmospheric pressure, controller PA6951 modulates the guide vanes towards the closed position by increasing the control air pressure to the pneumatic actuator.
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Term
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Definition
§The D/P control system sends a signal to All 3 exhaust fan inlet guide vanes, even when a fan is stopped.
§Guide vanes fail open on a loss of air or power.
§Guide vanes are mechanically prevented from closing more than 66% open.
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Term
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Definition
1 Normal Area Exhaust Duct
§Continuously draws air from supply duct discharges past equipment and into pump areas
2 Emergency Area Exhaust Ducts
§Serves the vital pumping equipment locations and the Containment Building penetrations, areas that are susceptible to high levels of radioactive contamination during postulated LOCAs
§Can only be routed to 21 or 22 HEPA units and if necessary, through the 24 Charcoal unit prior to release.
Manual balancing dampers are used to set flows and D/Ps.
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Term
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Definition
§The following ECCS dampers were identified as having a potential for single failure/closure that would result in ABV system inoperability.
§The closure of these dampers would result in an isolation of flow through the charcoal filters and reduced emergency flow through the charcoal filters.
§1/2 ABF225 – Piping Penetration Area Exhaust Fire Damper
§1/2 ABF221 – Charging Pump Area Exhaust Fire Damper
§1/2 ABF806 – RHR Area Exhaust Fire Damper
§1/2 ABF11 – Charging Pump Area Exhaust Fire Damper
§1/2 ABF13 – RHR and SI Pump Room Exhaust Fire Damper
§1/2 ABF14 – Piping Penetration Area Exhaust Fire Damper
§1/2 ABF15 – Piping Penetration Area Exhaust Fire Damper
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Term
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Definition
§A Containment Purge is a gas release of the Containment atmosphere via the Plant Vent, and is only performed in Modes 5, 6, and defueled.
§VC1 & 4 are C/T closed during Modes 1-4.
§NCO opens Containment inlet (VC1 ) and outlet (VC4) valve.
§This causes the interlocked Diversion Damper ABV20 to close, thus isolating 22 Supply Fan discharge from the normal AB Supply ducts and directing its discharge to Containment.
§The purge exhaust can be directed to either 23 Exhaust Filter or to 22 Exhaust Filter plus Charcoal, as dictated by air sample results.
§Use of 22 HEPA + Charcoal exceeds TS flow limits for the Charcoal Filter, making it inoperable.
§ABV Supply Fan 22 is used for the purge supply, and all three Exhaust Fans are normally to be in service.
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Term
| Containment Purge cont... |
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Definition
VC1 & 4 will auto close on SI, Phase A isolation, loss of power, and loss of air, high rad on R12B or R41D.
•VC1 & 4 are C/T during Modes 1-4 with the VCF2 & 3 flanges installed.
•ABV20 interlocked with VC1: closes when VC1 opens
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Term
| Safety related Room Coolers: |
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Definition
RHR Pump (2)
Charging Pump (3)
SI Pump (1)
CS Pump (2)
Auxiliary Feed Pump (1)
CC Pump Room Cooler (2)
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Term
Safety Related Room Cooler Features |
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Definition
RP2 CMC AUTO:
§Coolers start and stop at room temperature setpoints: 100 / 90°F— local thermostats
RP2 CMC MANUAL:
§Bypasses temperature switch
SEC Contact :
§Mode 1 – Cooler operates normally with no lockout
§Mode 2-4: Cooler may be locked out for 20 minutes on SEC (not all coolers are affected)
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Term
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Definition
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COOLER
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Room Design Basis Temp.
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RP2 Auto Start-Stop*
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S1 Key
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SEC** Interlock
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SI Pump
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120ºF
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100 - 90ºF
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—
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—
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CC Pumps
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120ºF
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100 - 90ºF
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X
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—
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AF Pumps
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120ºF
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100 - 90ºF
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X
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—
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Centrifugal Charging Pumps
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120ºF
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100 - 90ºF
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X
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X
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PD Charging Pump
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110ºF
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100 - 90ºF
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X
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X
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CS Pumps
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115ºF
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100 - 90ºF
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—
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X
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RHR Pumps
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120ºF
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100 - 90ºF
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X
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X
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