Containment HVAC (HC)

Question 1

What provides cooling to the Containment Normal ACUs?

Answer 1

Normal Chilled Water System (WC)

Question 2

What is the temperature limit of LCO 3.6.5 Containment Air Average Temperature?

Answer 2

LCO 3.6.5 Containment Average Air Temperature
* ≤ 117°F
* Modes 1-4
* 8 hours to restore
* 120°F is initial temp assumed in accident analysis (117°F accounts for instrument inaccuracies)
* Ensures max design temp of the CTMT steel liner (300°F) is not exceeded.
* MSLB most limiting (244°F)
* **Average temp **determined using 5 of the 7 TIs.

Question 3

What is the limit in LCO 3.6.4 Containment Pressure?

Answer 3

LCO 3.6.4 Containment Pressure
* ¬ LCO limits: -0.3 psig to 2.5 psig (1.8 psig indicated)
* Modes 1-4
* 1 hour to restore
* Upper Limit:
o Does NOT account for instrument accuracy. Indicated limit is 1.8 psig (use NR PTs for ST)
o Ensures max peak pressure (8.0 psig) is not exceeded.
o Ensures max accident design pressure (60 psig) is not exceeded.
o DB LOCA is most limiting (58 psig).
* Lower Limit:
o Ensures negative design pressure (-4.0 psig) not exceeded during inadvertent spray actuation

Question 4

What kind of valves are the Ru-1 sample and return line valves?

Answer 4

Radiation Monitor RU-1 / Isolation Valves
RU-1 (Located in Aux Bldg)
Samples air from 90’ level of CTMT.
Sample and return line each have 2 SOV CIVs (fail closed)
Auto close on CIAS (can be overridden)
Powered by PKA/PKB (fail closed)

Question 5

What is the power supply for the Containment Normal ACU’s?

Answer 5

CTMT Normal ACUs (4)
* Recirculate and cool air inside CTMT (Suction 120’, Discharge to 100’ and 80’)
* Normally two fans running (A or B and C or D) with two in standby
o Each fan has a MCR HS (can PTL)
o A/B share a common duct, C/D share a common duct
Power: PGA/PGB

Question 6

What will trip a Containment Normal ACU? What will cause it to Autostart?

Answer 6

• Auto start:
  o Low air flow (∆P) on running fan for 60 seconds (A interlocked with B, C with D)
  o Amber light if breaker closed and normal after stop (Auto start / local breaker closure)
• Trips:
  SIAS:
  SIAS Override allows manual start, the low flow auto start remains blocked.
  Once SIAS is reset, HS taken to stop to clear the auto start block
  o* LOP:re-starts in 5 seconds (sequencer) if red flagged (MCR HS normal after start)

Question 7

What is the power supply for CEDM Normal ACUs? What system provides cooling?

Answer 7

• Power: PGA/PGB
• Cooled by NCW (EW can be aligned / priority load)

Question 8

What causes the CEDM ACU’s to trip and autostart?

Answer 8

Auto start:
** Low air flow (∆P) on running ACU for 120 seconds** (A/C fans start if low flow on B ACU)
Loss of one fan may not cause an auto start. Flow switch sees combined flow from both fans on an ACU.
Ensure you wait 120 seconds to start the standby fans, they may be rotating backwards. Need time to stop first.
Trips:
**SIAS ** (can be overridden)
SIAS Override allows manual start, the low flow auto start remains blocked.
Once SIAS is reset, HS taken to stop to clear the auto start block
LOP: re-starts in 55 seconds (sequencer) if red flagged (MCR HS normal after start)

Question 9

During a loss of CEDM cooling, how long will it take to damage coils?

Answer 9

Loss of CEDM Cooling (40AO-9ZZ20)
* If RCS ≥ 300°F, CEDM coils may be damaged within 40 minutes.
* Restore in 10 minutes or start a rapid shutdown (Secure from shutdown if restored in 40 minutes).
* Cooldown the RCS to < 300°F in the next 4 hours if not restored. Use the SNOW GOP.

Question 10

What are the power supplies for the Reactor Cavity and Pressurizer Space Normal Cooling Fans?

Answer 10

Reactor Cavity Cooling Fans (4)
* Power: NHN-M19 and M20 (SIAS load shed)
* Motor operated discharge dampers open/close when fan starts/stops
* Auto start: Low fan ∆P

Pressurizer Space Normal Cooling Fans (2)
* Two exhaust fans (one running/one standby) Air drawn into bottom of PZR space. Fans suction at top of PZR space.
* Power: NHN-M71 and M72 (SIAS load shed)
* Auto start: Low fan ∆P