Nuclear Cooling (NC)

Question 1

What are the Nuclear Cooling water system priority loads?

Answer 1

• Normal Chillers
• Nuclear Sample Coolers
• Control Element Drive Mechanism air cooling units
• RCP high pressure coolers, seal coolers, thrust bearing coolers and lube oil coolers
• Fuel Pool Cooling heat exchangers (not generally considered a “priority load”; even
  though they can be cooled by EW cross-tie, it is a separate manual alignment from the
  typical EW to NC priority loads cross-tie)

Question 2

What are the power supplies for NCN-P01A and NCN-P01B?

Answer 2

NCN-P01A and NCN-P01B receive running power from 4160 VAC non-class NBN-S01
and NBN-S02.

Question 3

What ESFAS signals cause Motor Operated Valves (MOV) NCB-UV-401 (NCW CNTMT UPSTREAM
SPLY ISOL VLV UV-401), MOV NCA-UV-402(NCW CNTMT DOWNSTREAM RETURN ISOL VLV) and MOV NCB-UV-403 (NCW CNTMT UPSTREAM RETURN ISOL VLV)?

Answer 3

All three NC containment isolation MOVs automatically close on a receipt of a CSAS.
Power supply: PHA-M37 (NCA-UV-402) and PHB-M34 (NCB-UV-401 & 403).

Question 4

How much NC flow is required for each RCP?

Answer 4

511 gpm

Question 5

What radiation monitor detects radiological contamination of the Nuclear Cooling Water system?

Answer 5

RU-6 RU-6 monitors the NC System for gross gamma activity.
NOTE: If the NCW system is being supplied by the Essential Cooling Water System, RU-6 is NOT
in the flow path, the monitor is still on line and would alarm if contaminated water were to migrate
to the detector but it is not expected to alarm due to no flow through the detector to transport the
contamination to the detector. Under these conditions, either SQN-RU-002 (RU-2) for ECWS “A”
or SQN-RU-003 (RU-3) for ECWS “B” is used to monitor for activity in the NC system depending
on what EW train is cross-connected to the NC System.

Question 6

What is the normal and backup supply of makeup to the Nuclear Cooling Water surge tank?

Answer 6

DW
*CM - Manual make-up available from Cooling Water Holdup Tank pumps (Back-up)

Question 7

What is the order of opening NCB-UV-401 (NCW CNTMT UPSTREAM SPLY ISOL VLV UV-401), MOV NCA-UV-402(NCW CNTMT DOWNSTREAM RETURN ISOL VLV) and MOV NCB-UV-403 (NCW CNTMT UPSTREAM RETURN ISOL VLV)

Answer 7

In order to prevent system pressure from lifting
the relief valves, the return valves (NCA-UV-402 and NCB-UV-403) must be opened prior to the
supply valve (NCB-UV-401).

Question 8

What will happen to the NC system on low discharge pressure of 79psig?

Answer 8

The standby NC pump will start and an amber light will be lit above the HS on B07

Question 9

How is NC temperature controlled?

Answer 9

NCW Temperature control
Manual flow control of NCW HX flow (outlet valve) and bypass flow.
Either the HX outlet valve or the bypass will remain FULL OPEN.
PCW outlet valve normally kept at 33% open (can be adjusted, normally not done)

Question 10

What is the design basis for the two safety relief valves NCE-PSV-0614 & NCE-PSV-0615?

Answer 10

Two 6” safety relief valves in CTMT
* Installed on NC return line inside containment.
* Lift at 135 psig
* Ensure closure capability of NC CIVs during RCP HP Seal Cooler leak by preventing header pressure from affecting proper operation of the MOVs.
* PRA requirement - maintains 10CFR100 limits from surge tank.

Question 11

What is the design basis for one inch relief valve NCE-PSV-0617?

Answer 11

o Located between the CIVs
o Protects the penetration from thermal expansion.
o Lifts at 150 psig.