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34 Cards in this Set

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a. Non-safety related (normal) HVAC - purpose
- The secondary containment HVAC systems serve several functions. The normal (non-safety related) supply and exhaust systems for the reactor enclosure and refuel floor maintain acceptable temperature in the respective areas under normal conditions and ensure building pressure is slightly less than atmospheric pressure. They also provide for an elevated release path for air exhausted, and continuously monitor radioactivity being released. In the reactor enclosure, areas of higher potential contamination are exhausted through a filtered exhaust system (Reactor Enclosure Equipment Compartment Exhaust), further limiting released activity.
b. Reactor Enclosure Recirculation System (RERS) - purpose
- Under abnormal conditions, the normal supply and exhaust systems in the affected areas will trip. The safety related systems will automatically start. The air in the reactor enclosure affected will be recirculated through charcoal filters by the Reactor Enclosure Recirc System, reducing airborne contamination.
c. Standby Gas Treatment System (SGTS) - purpose
- A second charcoal filtered system, Standby Gas Treatment, will take a suction on the affected area, maintaining the area at a negative pressure, and removing airborne activity from the air drawn from the area, limiting the activity released.
d. Safeguard Pump Room Unit Coolers - purpose
- Maintain temperature in HPCI, RCIC, CS, and RHR pump rooms low enough to ensure equipment operates correctly and the room remains habitable. In the case of each RHR and CS pump, one of two coolers must be operable for the each ECCS to be considered operable. They will operate automatically during normal or accident conditions. Each pump has two cooling coil and fan units normally cooled by service water, and cooled by Emergency Service Water (ESW) under accident conditions with a loss of normal service water. Since there are two RHR Pumps per RHR pump room (A and C, B and D) there are four total unit coolers in each RHR pump room, however, credit is only taken for the two coolers dedicated to (and aimed at) each pump motor. HPCI, RCIC, and each Core Spray Pump are in individual rooms, with two unit coolers each.
e. Steam Flooding Isolation Dampers - purpose
- Installed in the supply and return ducts to rooms containing high energy water or steam pipes. These series backpressure dampers automatically close upon sensing inside duct pressure 5” W.G. above outside duct pressure, indicating a large steam break. The safety function of these dampers is to contain steam, and prevent rendering equipment in other rooms inoperable due to steam spreading via HVAC ducts.
function of the following components:
b. Prefilters
- Pre-filter for removing dust and dirt which could clog the remaining filters
function of the following components:
c. HEPA filters
- Upstream HEPA filter for particulates
- Downstream HEPA filter for removal of any remaining particulates or any charcoal fines which break through
function of the following components:
d. Charcoal filters
- Charcoal adsorber bed, which holds up (adsorbs) iodine for decay
function of the following components:
e. Safeguard room coolers
- The safeguard room unit coolers operate automatically to maintain the respective ECCS equipment operable. Each fan is 100% capacity, with its own cooling coil. Each pump has two fans dedicated to it.
function of the following components:
f. Steam flooding isolation dampers
- Redundant series isolation dampers are installed in the supply and exhaust lines for rooms containing steam or high energy water lines. (See P&ID M-76, Sheet 5 Table J for a listing.)
- The dampers are normally open. When actuated, they close by means of a weighted arm. A DC solenoid energizes to release the weighted arm, isolating the duct.
function of the following components:
g. Charcoal filter deluge (explain why it is needed)
- The iodine which can accumulate in the charcoal can generate significant decay heat. The possibility exists that it could ignite the charcoal. To protect against the damaging effects of a fire, the filter banks are equipped with a high temperature alarm on panel *0C205, and manually initiated (locally) fire protection deluge.
- 200°F causes a MCR alarm "*0C205 Trouble"
- Charcoal bed temperature is indicated on *0C205. Procedures direct that the bed will be sprayed if temperature exceeds 550°F.
- Ignition temp is ~600°F
function of the following components:
h. Blowout Panels
- Once a room with a large steam leak is isolated, pressure will continue to rise until a blowout panel actuates, to protect the building integrity. (The dampers hold pressure higher than required to lift the blowout panels.) Later, the damper must be locally relatched.
- HPCI/RCIC to valve room 0.1 psid
- Valve room to outside .5 psid
- RWCU to outside .5 psid
- Steam Tunnel .5 psid
effect that a loss or malfunction of the Reactor Enclosure Ventilation System will have on the following:
a. Secondary Containment Temperature
- Under isolation conditions, air is no longer drawn through the supply heating and cooling coils, which will affect zone temperatures.
effect that a loss or malfunction of the Reactor Enclosure Ventilation System will have on the following:
b. Secondary Containment Pressure
- A trip of normal HVAC will cause zone DP to decay. A failure of supply fans to trip on a loss of exhaust fans can cause actuation of blowout panels.
effect that a loss or malfunction of the following will have on the Standby Gas Treatment System.
a. AC Power
- SGTS fans are powered as follows from Safeguard 480 VAC:
0AV163 D114-R-C (Div. 1)
0BV163 D124-R-C (Div. 2)
- Notice that both are powered from Unit 1 Div. 1 and Div. 2. This makes these divisions very important for Unit 2, since SGTS is common. A loss of SGTS operability will require both units to shut down.
effect that a loss or malfunction of the following will have on the Standby Gas Treatment System.
b. Isolation Logic
- Normally, both SGTS fans are in AUTO. Consequently, both fans will start on a full RE or RF isolation (this assumes both divisions of logic trip).
effect that a loss or malfunction of the following will have on the Standby Gas Treatment System.
c. Secondary Containment High In-Leakage
- When drawing on Zone 1 or Zone 2, the SGTS flow should be 2500 cfm or less. Zone 3 flow should be 764 cfm or less. After initial draw-down of the zone, the indicated SGTS flow represents the zone in-leakage.
effect that a loss or malfunction of the Standby Gas Treatment System will have on the following:
a. Secondary Containment and Environment Differential Pressure
- SGTS maintains a negative pressure in those areas that are isolated. A loss of SGTS would allow the pressure in the RE/RF area to equalize with outside pressure.
effect that a loss or malfunction of the Standby Gas Treatment System will have on the following:
b. Off-Site Release Rate
- The SGTS draws air from those areas that are isolated and filters the exhaust prior to its release to the North stack. A loss of SGTS will allow the pressure in the affected zone to equalize with the outside air pressure and uncontrolled radiological releases can occur at any zone opening.
RE/RF HVAC Supply fan start permissives
Mode switch in RUN
Fan starts, and discharge damper opens provided all of the following are met:
1. At least two exhaust fans running
2. Both isolation dampers open
3. REECE operating (flowswitch) for RE supply
4. Zone pressure between the HI HI (pos) and LO LO (neg) trip setpoints (+/-3.5" H2O RE/+/-2.7" H2O RF)

Mode switch in AUTO
Fan will start immediately if either running fan stops, provided all normal start interlocks for RUN are met.
RE/RF HVAC Supply fan trips
RE/RF HVAC fans trip after a 13/20 second time dealy on any of the follwing conditions:
- Control switch to stop
- Discharge damer closes or fails to open
- any start condition is not met … i.e.
- < two exhaust fans
- either isolation dampers closed
- REECE not operating
- Zone pressure out of band (+/-3.5" H2O RE/+/-2.7" H2O RF)

A fan running in AUTO will trip if the other two fans are running
RE/RF HVAC Exhaust fan start permissives
Mode switch in RUN
Fan starts, and discharge damper opens provided all of the following are met:
1. Both series isolation dampers open
2. Zone pressure between the HI HI (pos) and LO LO (neg) trip setpoints (+/-3.5" H2O RE/+/-2.7" H2O RF)


Mode switch in AUTO
Fan will start immediately if either running fan stops, provided all normal start interlocks for RUN are met.
RE/RF HVAC Exhaust fan trips
RE/RF HVAC fans trip after a 6/8 second time dealy on any of the follwing conditions:
- Control switch to stop
- Discharge damer closes or fails to open
- any start condition is not met … i.e.
- either isolation dampers closed
- Zone pressure out of band (+/-3.5" H2O RE/+/-2.7" H2O RF)

A fan running in AUTO will trip if the other two fans are running
REECE fan start permissives
Mode switch in RUN
Fan starts, and discharge damper opens provided all of the following are met:
1. Both series isolation dampers open
2. Zone pressure between the HI HI (pos) and LO LO (neg) trip setpoints RE +/-3.5" H2O


Mode switch in AUTO
Fan will start immediately if either running fan stops, provided all normal start interlocks for RUN are met.
REECE fan trips
REECE fans trip after on any of the follwing conditions:
- Control switch to off
- Discharge damer closes or fails to open
- fan discharge flow is low with 30 sec time delay, sensed by FSL *38A,B (same sensor for RE supply fan start permissive)
- any start condition is not met … i.e.
- either isolation dampers closed
- Zone pressure out of band (+/-3.5" H2O RE)

A fan running in AUTO will trip if the other fans is running
RERS fan start permissives
Mode switch in AUTO
Fan auto starts in response to CORRESPONDING DIVISION RE isolation signal


Mode switch in STBY
Fan auto starts if following are met:
1. Corresponding division isolation signal has been present for 85 seconds, and
2. Low flow condition exists for other fan
.
All fans are prevented from starting for 3 minutes following a restoration of power to the 480V load centers (LOCA or LOOP). 85 and 65 sec timers start after 3 mins.
RERS fan trips
RERS fans trip on any of the follwing conditions:
- Fan Low Flow ~50000 cfm for 65 secs sensed at fan discharge

A fan running in STBY will trip if the other fan is running
SGTS fan start permissives
Mode switch in AUTO
Fan auto starts in response to CORRESPONDING DIVISION RE or RF isolation signal and dampers modulate based on the zone with least DP
.
Switch placed to STBY AFTER an auto start.(procedure on both fans auto starting)
Fan starts after five seconds of low flow from the other fan (assuming a corresponding division isolation signal exists)

NOTE: a fan started by placing HS in RUN will have dampers go full open (need initation signal to modulate flow)
SGTS fan trips
RERS fans trip on any of the follwing conditions:
- Fan Low Flow for 15 secs
- in AUTO or STBY if corresponding divicion of isolation logic is reset by operator

A fan running in STBY will trip if the other fan is running
Drywell Purge start permissives
Fan in RUN if both suction isolation dampers are open

Fan in AUTO starts if the other fan is not running, and suction dampers are open
Drywell Purge fan trips
Running fan will trip on any of the following:
low flow existing for 10 seconds, or
either suction isolation damper not fully open

A purge fan in atuo will trip if the other fan is running.
Safeguard Room Coolers
Fun in AUTO:
- Pump running: Fan runs continuously
- Pump not running: Starts at 100°F (Hi) Stops at 80°F

Fan in STBY:
- Pump running and other fan not running: Runs continuously
- All other times (regardless of pump status): Starts at 110°F (HI-HI) Stops at 80°F.

**"Pump running" is sensed by breaker position for motor driven pumps, and by discharge pressure for HPCI and RCIC (125 psig).
REACTOR ENCLOSURE ISOLATION SIGNALS
Manual - Arm & Depress
Exh. Hi Rad - 1.35 mR/Hr (A&B or C&D)
Low RPV level - 38" (A&B or C&D)
High DW pressure - 1.68# (A&B or C&D)
SGTS Damper open - not full closed
Low Zone DP - -0.1" WG for 50 mins ( A or B)
RF Isolation - if slide gate dampers open and not bypassed by keys in AER.

Response:
isolation dampers close
supply and exhaust fans trip due to isolation dampers closing
SGTS parallel connecting dampers open
SGTS fans start (both in auto)
Group 6A and 6B CAC valves recieve isolatoin signals on both units.
REACTOR ENCLOSURE ISOLATION SIGNALS
Manual - Arm & Depress
Exh. Hi Rad - 2.0 mR/Hr (A&B or C&D)
SGTS Damper open - not full closed
Low Zone DP - -0.1" WG for 100 sec ( A or B)
RE Isolation - if slide gate dampers open and not bypassed by keys in AER.
Other Unit RE isolation

Response:
isolation dampers close
supply and exhaust fans trip due to isolation dampers closing
SGTS parallel connecting dampers (to unit 1 supply) open
SGTS fans start (both in auto)
Group 6A and 6B CAC valves recieve isolatoin signals on both units.