RBVS

Question 1

What is the purpose of RBVS and how does it accomplish this?

Answer 1

Maintains dP to minimize ground level release, not necessarily for accident conditions i.e. 10 CFR 100
Provides negative dP to ensure leakage is always into the building.
RBVS provides a complete exchange of 1 volume of Rx building air per hour

Question 2

Where are the RBVS room coolers located?

Answer 2

Room Coolers (2 per room)
1. HPCI, RCIC, RHR, Cores Spray (all cooled
by SACS)
2. SACS Room (Cooled by Control Room
Chilled Water AP400/BP400)
3. Steam tunnels (normally cooled by
chilled water, can be cross tied to RACS)

Question 3

What do the RBVS duct heaters keep the various room temperatures at?

Answer 3

1. Maintain HPCI and RCIC rooms >60F
2. Maintain SLC room temp >70F
3. Maintain Rx Building >40F

Question 4

how does the RBVS fan trips/isolations remove power and how is power resored?

Answer 4

RBVS fans trip and dampers isolate (trips the 1E breaker [in the field] which indirectly feeds the RBVS supply and exhaust fans, must be locally reset AND started at breakers [1E swgr pistol grip switches])

Question 5

What are the RBVS fan trip and damper isolation setpoints?

Answer 5

• Drywell pressure (1.68psig)
• RPV Level 2 (-38”)
• Rx Building Hi Rad (1X10-3uci/cc)
• Refuel Floor Hi Rad (2X10-3uci/cc)
• Lo Flow (<30,000scfm w/ 90sec TD – by say, outlet damper closure)
• Non 1E Breaker trips on undervoltage.
• These are PCIS NOT NSSS isolations ONLY

Question 6

What prerequisites must be met before re-shutting a tripped RBVS 1E Breaker?

Answer 6

To reclose the 1E breaker, all initiating signals must be clear and
PCIS reset; then, the breaker must be manually reclosed at the
480V USS. (Top breakers on 10C650)

Question 7

Describe RBVS and RBVE fan auto start operations and interlocks.

Answer 7

• Low flow (<30000scfm for 90seconds)
• Two exhaust fans must be running to start a supply fan (if at any
  time < two exhaust fans are running, all supply fans trip).
  * This trip looks at the non-1E
  breaker position => when
  the 1E breaker trips, the non-1E
  breaker will trip on U/V.
• LOP sequencer will start all RBVS & RBVE fans in RUN 19
  seconds after the event (The RBVS fans will actually start
  6 seconds after the RBVE fans start).

Question 8

When do the RBVS steam leak dampers close?

Answer 8

Close on room high temperatures