Secondary Containment HVAC (T41)

Question 1

What is the power supply for the Rx Zone Supply Vent fans and the R/F Zone Supply vent fans?

Answer 1

600V AA MCC (R24-S015)

Question 2

What is the power supply for the U1 Rx Zone ACCESSIBLE Exhaust ventilation fans?

Answer 2

600V AA MCC (R24-S015)

Question 3

What is the power supply for the U2 Rx Zone recirc cooler, U2 Rx Zone exhaust Vent fans, U1 Rx Zone INACCESSIBLE exhaust vent fans, and R/F Zone exhaust vent fans?

Answer 3

600V BB MCC R24-S016

Question 4

What are the isolation signals for the Secondary Containment HVAC system?

Answer 4

Isolation Signals (A/B inboard & C/D outboard)
- U1 or U2 Rx Zone exh high rad - 18 mR/hr on K609A-D

• U1 or U2 R/F Zone exh high rad - 18 mR/hr on K611A-D
  U2 ONLY – 6.9 mR/hr on K634A-D
  U2 ONLY - 5.7 mR/hr on K635A-D
• U1 or U2 High Drywell pressure - 1.85 psig
• U1 or U2 Low Low RWL -35”

Question 5

Where does Secondary Containment HVAC maintain Rx Building and R/F pressure?

Answer 5

Secondary Containment HVAC maintains a slight negative pressure in Rx Bldg & Refueling Floor

-0.20” H20

Question 6

What are the major flowpaths for Secondary Containment HVAC in U2/U1?

Answer 6

• Air is circulated thru U2 Rx Bldg from accessible areas to inaccessible areas by a recirc cooling unit
• Circulation of air thru U1 Rx Bldg is by natural circulation from discharge of supply fan to suction of exhaust fan

Question 7

For Unit 2, which Secondary Containment HVAC valves will close on an isolation signal?

Answer 7

Unit 2 Rx Zone:
Supply valves F011A/B provide auto isolation w/ isolation signal
Exhaust isolation valves F044A/B provide auto isolation with signal

Unit 2 R/F Zone:
RF Zone Exhaust isolations F023A/B

Question 8

What is the normal configuration and interlocks for the Secondary Containment HVAC supply fans / RF Zone supply fans?

Answer 8

Unit 2:
- 1 fan in RUN & other in STBY, if fan in RUN trips, fan in STBY will start unless an isolation signal is present

• Supply fan cannot be started unless exhaust fan already running & trips if running exhaust fan trips

Unit 1:

• 1 fan in RUN & other in STBY, if LOW SYSTEM FLOW is sensed fan in STBY starts unless an isolation signal is present
• Running fan will continue to run

U1/U2
Both fans trip & associated pitch control valves close on: Isolation signal & Motor overload

Question 9

What is the normal configuration and interlocks for the Secondary Containment HVAC exhaust (inaccessible exhaust U1) / RF Zone exhaust fans?

Answer 9

Unit 2:
- 1 fan in RUN & other in STBY, if fan in RUN trips, fan in STBY starts unless isolation signal is present

Unit 1:

• 1 fan in RUN & other in STBY, if LOW SYSTEM FLOW is sensed, fan in STBY starts unless isolation signal is present
• Running fan will continue to run
• Both fans trip and associated pitch control valves (U1 discharge valves) close on:
• Isolation signal & Motor overload
• U2 - Exhaust filter train high temp / U1 - Exhaust filter train deluge system actuation

Question 10

What effect does a loss of RPS have on Secondary Containment HVAC for Unit 2? Unit 1?

Answer 10

U2:
RPS ‘A’ ONLY: No affect. U1 & U2 Sec Containment and SBGT not affected. Logic powered from Instrument Bus A.

U1:
Loss of A – Half PCIS Gp 2 isolation (inboard); SCIS isolation & Both unit SBGT start (SCIS logic powered from RPS)
Loss of B – Half PCIS Gp 2 isolation (outboard); SCIS isolation & Both unit SBGT start (SCIS logic powered from RPS)

Question 11

What system supplies cooling water to the 10 SEC coolers? What system provides cooling water to the Rx Building Coolers?

Answer 11

SEC Coolers: PSW

Rx Building Coolers: Rx Building Chilled Water
U2 - 11 equipment area coolers
U1 - 6 equipment area coolers

Question 12

How many SEC coolers are normally in operation?

Answer 12

During normal ops on both units:
1 SEC cooler is running in CRD diagonal (cools running CRD pump), in RCIC room & in HPCI room

All other SEC coolers are secured

Question 13

What is the time restriction if both SEC room coolers in a diagonal are lost?

Answer 13

34AB-T41-001, Loss of ECCS, MCREC or Area Ventilation System(s)

IF both S.E.C. Room Coolers in a diagonal are lost, the availability of the RHR/CS pumps in
that diagonal can be assured for at least 24 hours, IF no more than one pump is operated at a
time and the RHR/CS pump is the only significant source of heat addition to the diagonal.