CVCS

Question 1

How does CVCS supply borated water to RCS and RCP seals during a LOCA

Answer 1

• Start both charging pumps
• Open IMO-910,911 charging pumps suction from RWST
• Open ICM-250,251 Boron Injection Tank Inlets
• Open ICM-255, 256 Boron Injection Tank Outlets
• Close QMO-451 and QMO-452 charging pump suction from VCT
• Close QMO-200 and QMO- 201 charging flow to regen heat exchanger
• close QMO-225, 226 Charging pump ELO’s
  
  • Reopens after 2 seconds if RCS pressure greater than 1825 PSIG

Question 2

How does CVCS ensure borated water to the RCS and RCP Seals with loss of power

Answer 2

• IF SI present Charging pumps restart 3.16 seconds after diesel is at speed and voltage
• If NO SI RO must restart pump manually
• Charging pump trips will cause
  
  • Letdown orfice isolation valves to close

Question 3

QRV-111 and 112 Letdown Isolation Valves

Answer 3

• Close on PZR low level to prevent uncovering heaters
• Interlocked to prevent opening unless orfice isolation valves are closed

Question 4

Letdown orifices

Answer 4

Reduce Coolant pressure and control flow of reactor coolant leaving RCS

Question 5

Letdown Heat Exchanger

Answer 5

Cools letdown flow from 290 to 127 to protect resins in the CVCS Demineralizers

Question 6

QRV 301 Letdown pressure control Valve

Answer 6

• Maintains backpressure between 300 and 350 psig to preent flashing downstream of the letdown orifices

Question 7

Filters/ Demineralizers

Answer 7

Mixed bed: Remove lithium

Cation bed: Backup lithium removal

Deborating Bed: Anion resins reduce boron concentration when deluting nolonger practical

Question 8

Describe VCT

Answer 8

• Surge Volume for RCS and CVCS
• NPSH for charging pumps
• Means of introducing hydrogen in RCS
  
  • Hydrogen scavenges oxygen
• Means of degassing RCS

Question 9

Describe the Charging Pupms

Answer 9

• Power Supplies
  
  • East T-11D
  • West T-11A
• Flows
  
  • Normal 150 gpm
  • runout 550 gpm
• Pressure
  
  • Shutoff Head 2530 psig
• Autostart
  
  • SI
  • Manual from control room
  • Manual from hot shutdown panel
• Auto trip on
  
  • Loadshed
  • Overload
  • Overcurrent

Question 10

how is seal water maintained

Answer 10

QRV 200 maintains backpressure on charging header to force water through the RCP seals

Question 11

RCP seal injection and return flowpaths

Answer 11

1. Seal water injection filters
2. seal injection reg valves
3. rcp seals
4. rcp seal water return valves
5. seal water return filter
6. seal water heat exhanger

Question 12

VCT responses

Answer 12

1. Lowering Level
   
   1. 14% auto makeup starts
   2. 2.5% auto aligns charging pumps suction to RWST
2. Rising Level
   
   1. 24% auto makeup stops
   2. 87% auto divert letdown to CVCS HUTS
3. Rising Temperature
   
   1. High temperatures will affect the affinity of the demin which will actually release boron in to the system
4. Lowering Temperature
   
   1. lower temperatures affect the affinity of the demin and will pull boron from the system

Question 13

Qrv 111 and qrv 112 letdown isolation valves isolate on what signal

Answer 13

Pressurizer low level (17%) to prevent uncovering the heater elements.

Question 14

five functions of the volume control tank

Question 15

five functions of the volume control tank

Answer 15

surge volume

npsh for charging pumps

means to add hydrogen to rcs

means to degas

provides back pressure to the rcp seals

Question 16

four signals will autoclose regen hx outlet valves

Answer 16

phase A

low pressurizer level

loss of operating charging pump

qrv 111, 112 letdown isolation valves close