Recirc Flow Control Flashcards
What is the purpose of the Recirc Flow Control?
Allows for the remote and fast control of reactor power by providing a means to change core flow.
What happens to runbacks if the ASD switch is in “local”?
All runbacks are disabled.
If runback signal occurs - switch must be taken to remote and alarm reset Pushbutton pressed twice to have runback actuate
What happens to runback signals if a speed hold is in?
All runbacks are disabled.
Where are the RR/ASD Speed change controllers?
902-5 - master control
902-4 - Individual Control
- signal sent to I/O cabinet behind WEC
What is the RR Speed Limiter and when is it active/when bypassed?
It limits the RR speed to 30% unless RR Discharge vlv full open and feedwater flow >2Mlbm/hr for 15sec - ensures NPSH
What are the speed changes associated with each RR Button?
Lo - 1 RPM - 0.06%
Medium - 3 RPM - 0.18%
Hi - 15 RPM - 0.9%
What does the speed limitation protect?
30% - Ensures adequate flow exists in RPV lower head to prevent startification of cool water from CRD system - this could cause thermal stress on stub tube welds
100% max - protects pump/motor damage - prevents exceeding 108% core flow
What powers the RR Individual COntroller?
ESS Bus
What is the Recirc EPU Runback
Recirc Runs Back to 68% at rate of 7.5%/sec to prevent low level scram on loss of feed water -
Engages if:
>9.8Mlbm/hr Stm flow AND
<3RFP AND <25” water level OR
<4C/CB Pp and >10.3 Mlbm/hr FW flow
What is the Recirc Min Speed (Anti-Cav Runback)?
If RR Pp Speed >30% and initiated - RR Pps run back to 30% speed at rate of 2.5%/second
Initiation - Discharge Vlv not full Open
OR FW flow drops below 2Mlbm/hr for 15 sec
What do the High Level and Low Level Recirc Runback pushbuttons do?
High level runs pump speed demand to 68%
Lo level runs pump speed demand to 30%
What is the purpose of the Recirc Flow Mismatch Circuits?
Prevent Jet Pump Vibrations and confusing LPCI loop select logic
