Nuclear Cooling Water

Question 1

What are the priority loads on NC?

Answer 1

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

Question 2

What are the non-priority loads on NC?

Answer 2

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

Question 3

What cools NC?

Answer 3

PW

Question 4

Draw NC.

Answer 4

include all loads

Question 5

What is the normal discharge pressure of the NC pump?

Answer 5

85-90 psig with one pump normally running

Question 6

What are the power supplies to the NC pumps?

Answer 6

NBN-S01 & S02

Question 7

What will cause the standby pump to start?

Answer 7

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

Question 8

Why is NC pressure maintained below PW pressure?

Answer 8

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

Question 9

Where is makeup water added to the NC system?

Answer 9

to the surge tank automatically from DW system.

Question 10

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

Answer 10

5 psig

Question 11

What system supplies backup makeup water to the surge tank?

Answer 11

Chem waste system Cooling Water Holdup tank (Manually)

Question 12

How are chemicals flushed through the chem add tank?

Answer 12

Using D/P of the running NC pump.

Question 13

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

Answer 13

proper PPE and a portable eye wash station

Question 14

What does RU-6 monitor the NC system for?

Answer 14

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

Question 15

How is temperature regulated in the letdown HX?

Answer 15

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

Question 16

How does letdown temperature affect reactivity?

Answer 16

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.

Question 17

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

Answer 17

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)

Question 18

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

Answer 18

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.

Question 19

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

Answer 19

CSAS

Question 20

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

Answer 20

EW

Question 21

What pressure will cause the standby NC pump to start?

Answer 21

79 psig (alarm is at 80psig)

Question 22

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

Answer 22

by throttling the component HX outlet valve

Question 23

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

Answer 23

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

Question 24

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

Answer 24

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

Question 25

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

Answer 25

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