Nuclear Cooling Water Flashcards
What are the priority loads on NC?
WC
Sample Coolers (nuclear)
CEDM normal ACUs
RCP coolers (thrust brg, LO, seal, & motor)
What are the non-priority loads on NC?
Letdown HX BAC RU-7 cooling Non nuclear sample coolers Spent Fuel Pool HX Waste Gas compressor Aux steam vent condenser Gas Stripper Rad Waste Evaporator
What cools NC?
PW
Draw NC.
include all loads
What is the normal discharge pressure of the NC pump?
85-90 psig with one pump normally running
What are the power supplies to the NC pumps?
NBN-S01 & S02
What will cause the standby pump to start?
Low discharge header pressure of 79 psig due to the loss, degradation of the running pump or the improper operation of the system.
Why is NC pressure maintained below PW pressure?
to prevent potentially contaminated nuclear cooling water leakage into PW and to the environment
Where is makeup water added to the NC system?
to the surge tank automatically from DW system.
What pressure is N2 cover gas supplied to the surge tank at?
5 psig
What system supplies backup makeup water to the surge tank?
Chem waste system Cooling Water Holdup tank (Manually)
How are chemicals flushed through the chem add tank?
Using D/P of the running NC pump.
What must you have on station when you are adding chemicals?
proper PPE and a portable eye wash station
What does RU-6 monitor the NC system for?
Gamma activity that would come from a leak into the NC system from the primary.
How is temperature regulated in the letdown HX?
by an automatic valve that throttles NC flow through the HX. It maintains flow to keep temperature about 120F.
How does letdown temperature affect reactivity?
The cooler the temperature, the more resin holds onto Boron and => positive reactivity is added.
The higher the letdown temp, the more boron is released by the resin, so more negative reactivity.
Why was a relief valve added to the NC system in containment in the return line?
to protect the piping through the containment penetration from exceeding its design pressure rating after a LOCA. (containment valves would isolate a section of piping and that section could rupture with temp. changes if not protected)
What order should the containment return isolation valves be opened in upon returning the system to service to prevent lifting a relief valve?
NCA-UV-402 and NCB- UV-403 (NC containment return isolation valves) should be opened prior to opening NCB-UV-401 (NC containment supply valve). If removing it from service, 401 should be closed first.
What will cause the motor operated containment isolation valves to close automatically?
CSAS
What is the safety related backup source of cooling for NC priority loads?
EW
What pressure will cause the standby NC pump to start?
79 psig (alarm is at 80psig)
How are required flow rates through components supplied by NC established?
by throttling the component HX outlet valve
How much time do you have to restore NC flow to the RCPs before you have to trip the plant?
10 minutes unless there is no seal injection flow, then 3 minutes
How is EW cross tied to NC on a loss of NC?
“A” train has motor operated valves, so the procedure can be completed mostly from the control room to restore flow to priority loads
How will the RCP low flow alarms need to be cleared after EW is cross tied?
by unlocking and throttling the SDHX EW outlet valve to raise flow enough to clear the alarms
