Turbine Bldg CW & HVAC (P63)

Question 1

What are the power supplies?

TB Chillers
TB Chill Water Pumps
TB Exhaust Fans

What is the restriction on alternate power for the exhaust fans?

Answer 1

Chillers:
‘A’ TB Chiller: R22-S003 (4160V C)
‘B’ TB Chiller: R22-S004 (4160V D)

Chill Water Pumps:
U1:  A - 1R25-S005 (600 AA)
       B - 1R25-S006 (600 BB)
U2: A - 2R24-S035A (600 B)
       B - 2R24-S035B (600 A)

Exhaust Fans:
Normal Power 600V MCC G (R24-S016 via 600 BB)
Alternate Power R24-S011 (EOP/SAG’s)

Both exhaust fans on each unit have manual transfer switches (164’ TB, UP=ALT, DOWN=NORMAL) but due to EDG loading only ONE fan per unit is allowed to be powered from alternate power.

Question 2

What are the TB Chiller trips?

Where are trips reset?

Answer 2

LOCA (No Override): -101” or 1.85#
Station Service Fast Transfer or Loss of Power

BOTH UNITS TB Chillers trip on LOCA

STBY chiller will autostart on trip of running chiller

If running, U1 TB chillers will trip on SS Fast Transfer or Loss of power and will automatically restart when power is restored.

U2 – All trips require reset at local chiller
U1 – Trips will auto reset (except Overcurrent & Low Water Flow)

Question 3

What are the U2/U1 TB Chiller Timers?

What are the procedural restart time precautions?

Can chillers be operated in parallel?

Answer 3

U2 TB Chiller Timers
3 min TD stop to start
15 min TD start to start
12 hr timer prevents more than 3 starts in 12 hours

U1 TB Chiller Timers
150 sec TD stop to start
30 min TD start to start

Two starts in succession from ambient temperature OR
One start from rated temperature is allowed
Prior to NEXT start, allow 30 min running time OR 60 min idle time

U1 chillers CANNOT be operated in parallel
U2 chillers CAN be operated in parallel

Question 4

How are TB Exhaust Fans used post-accident/DBA?

Answer 4

TB HVAC Exhaust Fans are integral part to Alternate Source Term (AST) calculations for MCR radiological dose analyses.
1 exhaust fan from either unit’s TB HVAC system
must be started w/in 9 hrs of the 3 applicable DBA’s
(LOCA with fuel damage, CRDA (Control Rod Drop
with fuel damage) & MSLB (Main Steam Line Break).
For purging area around MCR.

Fuel Handling Accident Results acceptable, no AST considerations required

To support AST, – supplied w/ NIEIA w/ N2 Backup
U1 & 2 Exh Fan Inlet Dampers
U1 Exh Fan Outlet Dampers
U1 & 2 Exh Filter Train Inlet Dampers

Trigger to initiate the TB HVAC purge is based on Drywell Rad levels of >200,000 R/hr.
Indication of significant fuel damage

Since TB exhaust ventilation system is not an ESF system, but is credited w/ providing an accident mitigation function: Exhaust fans & various exhaust dampers have been upgraded w/ reliable power & air to ensure AST analysis is fulfilled.

Question 5

What is the heat sink for U1/U2 TB Chillers?

Answer 5

U1 - Closed Cooling Loop Cooling Tower

U2 - PSW

Question 6

What is the T.S. mode and operability requirements for TB HVAC exhaust system fans?

Answer 6

Mode: 1, 2, and 3

LCO: One U1 and one U2 TB HVAC exhaust system fan shall be operable

A: One required not met, restore in 7 days

Question 7

What is the CAUTION for starting up U1 TB Chiller Condenser Water Pump based on cooling towers parameters?

Answer 7

PRIOR TO STARTING 1P63-C004A (1P63-C004B), CONDENSER WATER PUMP, CHECK THE WATER LEVEL FOR THE IN SERVICE COOLING TOWER BASIN IS AT THE OVERFLOW.

THEN ON 1P63-P003A(1P63-P003B) PANEL, DEPRESS TOWER PUMP RESET PUSHBUTTON, BECAUSE A LOW WATER LEVEL CONDITION IN THE 1P63-B002A (1P63-B002B) C/T BASIN SEALS IN A TRIP SIGNAL TO BOTH CONDENSER WATER PUMPS TO PREVENT STARTING OF EITHER PUMP.

IF THE WATER LEVEL IN THAT COOLING TOWER BASIN IS AT A LEVEL THAT CAN ACCOMMODATE PUMP OPERATION, THE RESET P/B WILL THEN REMOVE THE SEAL IN TRIP SIGNAL.

Question 8

Maintenance has been performed on the “2A” Turbine Building Chiller (2P63-B001A).

The chiller has been out of service for 18 hours

• At 12:00 the chiller is returned to service
• At time 12:35, the “2A” Turbine Building Chiller trips.
• At time 12:37, an attempt to restart the chiller (WILL/WILL NOT) violate procedural limits for motor starts; AND, the chiller (WILL/WILL NOT) start when this start attempt is made?

Answer 8

Part 1 - WILL NOT violate procedural limits. Since the chiller has been out of service for 18 hours, it is being started up from ambient temperature, therefore, 2 starts are allowed in succession.
If the chiller had been at rated temperature, only one start would be allowed unless it had been running for 30 minutes or been idle for 60 minutes.

Part 2 - the chiller WILL NOT start since the 3 minute restart timer had not timed out.

Question 9

What is the normal system lineup for TB HVAC?

What air supplies the exhaust dampers?

Answer 9

Normally both filter trains are in service with only 1 exhaust fan. Discharge is to the RB Plenum (Stack).

Air to the exhaust dampers is supplied from NIEIA with N2 backup to ensure the exhaust fans can be started within 9 hours of the 3 DBAs.