Nuclear Cooling Water Flashcards Preview

Secondary Systems > Nuclear Cooling Water > Flashcards

Flashcards in Nuclear Cooling Water Deck (25)
Loading flashcards...
1
Q

What are the priority loads on NC?

A

WC
Sample Coolers (nuclear)
CEDM normal ACUs
RCP coolers (thrust brg, LO, seal, & motor)

2
Q

What are the non-priority loads on NC?

A
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
3
Q

What cools NC?

A

PW

4
Q

Draw NC.

A

include all loads

5
Q

What is the normal discharge pressure of the NC pump?

A

85-90 psig with one pump normally running

6
Q

What are the power supplies to the NC pumps?

A

NBN-S01 & S02

7
Q

What will cause the standby pump to start?

A

Low discharge header pressure of 79 psig due to the loss, degradation of the running pump or the improper operation of the system.

8
Q

Why is NC pressure maintained below PW pressure?

A

to prevent potentially contaminated nuclear cooling water leakage into PW and to the environment

9
Q

Where is makeup water added to the NC system?

A

to the surge tank automatically from DW system.

10
Q

What pressure is N2 cover gas supplied to the surge tank at?

A

5 psig

11
Q

What system supplies backup makeup water to the surge tank?

A

Chem waste system Cooling Water Holdup tank (Manually)

12
Q

How are chemicals flushed through the chem add tank?

A

Using D/P of the running NC pump.

13
Q

What must you have on station when you are adding chemicals?

A

proper PPE and a portable eye wash station

14
Q

What does RU-6 monitor the NC system for?

A

Gamma activity that would come from a leak into the NC system from the primary.

15
Q

How is temperature regulated in the letdown HX?

A

by an automatic valve that throttles NC flow through the HX. It maintains flow to keep temperature about 120F.

16
Q

How does letdown temperature affect reactivity?

A

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.

17
Q

Why was a relief valve added to the NC system in containment in the return line?

A

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)

18
Q

What order should the containment return isolation valves be opened in upon returning the system to service to prevent lifting a relief valve?

A

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.

19
Q

What will cause the motor operated containment isolation valves to close automatically?

A

CSAS

20
Q

What is the safety related backup source of cooling for NC priority loads?

A

EW

21
Q

What pressure will cause the standby NC pump to start?

A

79 psig (alarm is at 80psig)

22
Q

How are required flow rates through components supplied by NC established?

A

by throttling the component HX outlet valve

23
Q

How much time do you have to restore NC flow to the RCPs before you have to trip the plant?

A

10 minutes unless there is no seal injection flow, then 3 minutes

24
Q

How is EW cross tied to NC on a loss of NC?

A

“A” train has motor operated valves, so the procedure can be completed mostly from the control room to restore flow to priority loads

25
Q

How will the RCP low flow alarms need to be cleared after EW is cross tied?

A

by unlocking and throttling the SDHX EW outlet valve to raise flow enough to clear the alarms