NC- Nuclear Cooling Flashcards
[NC]
Pump capacities
How many are normally in operation?
-2 pumps in parallel
-100%
-1/2
100-110 psig (17,500 gal/min)
[NC]
[NC] Pump power supply?
[NB]
‘A’ – NBN-S01 ‘‘B’ – NBN-S02
[NC]
What auto starts standby [NC] pump?
Pump discharge header pressure
79 psig
[NC]
How would the Control Room know if [NC] standby pump auto started?
Amber Light (Lit) in CR
[NC]
Which side does [PW] flow through on [NC] Hx (Tube or Shell?)
Tube Side
[NC]
To shift to standby Hx, what actions must be performed?
Vent on-coming Hx on both shell and tube side to ensure a filled condition.
[NC]
How do we manually adjust [NC] temperature?
What temperature band?
Temp Up - Open Flow Bypass Valve (bypassing Hx)
Temp Down - Close Flow Bypass Valve (more flow to Hx)
75-105*F
[NC]
Which system of the [NC] Hx, is at a higher pressure?
[PW]
to prevent potentially contaminated nuclear cooling water leakage into the PW system and environment
[NC]
[NC] Surge tank purpose? (4)
-Absorb fluxtuations in system due to temperature changes
-NPSH for [NC] pumps
-detecting leakage
-Location for adding makeup water
[NC]
Surge Tank location?
Capacity?
AB Roof (NE)
1000 gal
[NC]
Makeup water to [NC]?
What is it inserted into?
[DW] Demineralized Water
Surge Tank
[NC]
Backup makeup water source to [NC] ?
Where are the valves to align this back up make up source?
[CM] Chemical Waste System
100’ aux building, south wall
[NC]
Purpose of nitrogen in the Surge tank?
Cover gas -oxygen exclusion for corrosion
5 psig
[NC]
How are chemicals added to the system with th Chem Add Tank?
D/P with [NC] pump flush
[NC]
The NC Chem Add Tank is normally isolated. Besides adding chemicals, when would we align flow through it and why?
When Cold Weather Protection is in effect to prevent freeze damage
[NC]
What does RU-6 monitor?
Location?
[NC] in-leakage from the contaminated systems it cools
Turbine Building North Yard
Next to the [NC] pumps
[NC]
Letdown Hx TCV purpose?
Control [NC] flow thru Hx to auto regulate LDHx outlet temp setpoint by CR
NCN-TV-223 - (usually 120F) - AB 110’ above LDHx
[NC]
Why, as AO’s, should we worry about the flow of NC through the LDHX? What is the maximum NC flow rate through the letdown HXs?
Because it controls Letdown temperature and could ultimately affect reactivity
1500gpm
[NC] 10
What are the 8 Priority heat loads?
Normal Chillers
Nuclear Sample Coolers
CEDM Normal ACUs
[RC] RCP
Seal coolers
HP coolers
Thrust Bearing Coolers
Motor Air coolers
Lube Oil Coolers
[NC]
What is the purpose of the relief valve NCE-PSV-617?
Protect the containment NC return penetration from exceeding its design pressure rating after a LOCA
It protects the system between the inside and outside containment isolation valves
[NC]
Why are we worried about overpressure in the penetration piping for the NC system between the inside and outside isolation valves?
The water trapped in the penetration piping could be heated by the conditions in the containment and the resulting expansion might rupture the piping and cause a loss of containment isolation
[NC]
Why do we not have relief protection on the supply penetration piping for the NC system?
Because the inside containment valve is a check valve which would pass flow and therefore not allow any pressure accumulation in the piping
[NC]
What is the purpose of relief valves protecting NC inside containment?
Protect the NC system piping inside the containment against over pressurization and potential damage in the event of leakage from a RCP seal cooler into the NC system in conjunction with a closure of the NC containment isolation valves
[NC]
The setpoint for the NC inside containment relief valves is 135 psig. Why is that significant?
Low enough to require a special operating sequence for the NC motor operated containment isolation valves because isolation of the containment return path with the supply path still aligned can cause a pressure surge in the NC system that will lift the reliefs
[NC]
What types of valves are on the supply and discharge lines through containment for NC? What would cause the NC supply and return containment isolation valves to automatically shut?
supply line- motor operated outside, check valve inside
return line- motor operated valves inside and outside containment
CSAS
[NC]
What system provides a backup source of cooling water for NC system loads?
EW
[NC]
If NC is lost to the RCPs, how long would I have to restore it?
10 minutes
3 minutes if its lost to more than one RCP
[NC]
What temperature is NC maintained at and what is preferred?
Between 75F and 105F, but less than 85F is preferred
[NC]
The PW T-mod was designed to cool NC when the heat load consists of what components?
One Spent Fuel Pool heat exchanger
Two Normal Chillers at 50% load
BAC at 40% load
LRS Evaporator at 50% load
AS Vent Condenser
[NC]
What is the purpose of the NC system?
provide cooling during all modes of operation to the priority and non-priority loads
intermediate buffer volume between plant cooling water and potentially contaminated flow streams to reduce the probability of releasing radioactivity to the environment.
[NC]
Why is the NC constantly monitored by a radiation monitor around the NC pumps?
due to the potential for leakage into the NC system from other radioactive systems
[NC]
What protections does the NC surge tank have?
hi-lo level/pressure, level sight glass and controller, local temperature indicator, pressure relief and a vacuum breaker
[NC]
What potential impacts on the plant does manually controlling letdown temperature?
too much NC flow, letdown too cool, boron absorbed, positive reactivity
too little NC flow, letdown too hot, boron released, negative reactivity
[NC]
What are the NC “non-priority loads”?
letdown hx radwaste evaporator boric acid concentrator waste gas compressors non-nuclear sample coolers aux. steam vent condenser gas stripper aux. steam rad. monitor (ru-7) cooling coil spent fuel pool cooling hx
[NC]
What must be done prior to opening the EW-NC cross-tie valves?
close the NC non-priority load isolation valve
Where is the NC non-priority load isolation valve located?
77’ aux. building unassigned room
Where are the EW cross-tie to NC valves located?
70’ aux. building, shutdown cooling hx room
Are the isolation valves to transfer EW to NC for the fuel pool hx make-before-break?
yes
[NC]
In the NC system, what does NH power?
NC pump motor space heaters
CEDM ACU and normal chiller NC outlet valves
[NC]
In the NC system, what does NK power?
NC surge tank make up solenoid valve
[NC]
In the NC system, what does PH power?
NC containment isolation valves
[NC]
What is the back up cooling water system for the shutdown cooling HXs?
NC
[NC]
What is the back-up make-up system for the NC system?
CM
[NC]
Which [NC] Hx is the [PW] T-Mod usually hooked to?
B
[NC]
What status does cross-tying the EW to NC loads put the EW equipment in?
INOPERABLE
[NC]
What happens when NC is lost to the WC system?
normal chillers trip
[NC]
Are the NC supply and return line motor operated valves fail close or as is?
fail as is
[NC]
What is the tech spec related to the NC system containment isolation valves?
must be able to close in 60 seconds
