Incore NIs Flashcards
What is the purpose of Movable Incore Detection System (MIDS))
- Identify misaligned rod
- Maps radial / axial flux distribution to confirm core design parameters
- Determines magnitude / location of fuel burnup
- Perform flux profiles / QPTRs
What is the speed of the MIDS Drive Units in SLOW speed?
12ft/min while scanning core
What is the speed of the MIDS Drive Units in FAST speed?
72 ft/min from withdrawn to bottom of core
What does the Withdraw Limit Switch do?
Withdrawn - Stops drive motor & detector withdrawal
Inserted- Prevents operation of associated 5 & 10 path
What does the Safety Limit Switch do?
- Deenergizes drive motor
- Stops automatic MIDS withdrawal if the withdraw limit switch fails
Why do we hang a clearance on the Moveable Incore Detection System when not in use?
- Personnel Safety
- The clearance ensures that the detectors are in a safe location to allow for personnel entry into containment.
- The radiation fields produced by the detectors can be thousands of R/hr
What type of detector are the Incore NIs?
- Fission Chamber (6 of them)
- U308 coated, gas (argon) filled
What are the seal table valves for?
- Designed to close without cable through but has the ability to cut cable for emergency isolation.
- Prevent RCS leakage in case of thimble tube rupture
What does the leak detection system for the Incore NIs do?
- Monitors ten path transfer devices for thimble tube leaks
- Pressure switch provides an alarm to the control room for sufficiently sized leak in a thimble tube
- Pressure switch also opens drain solenoid valve and directs water to the sump
- When level decreases the alarm will extinguish and drain valve will close
Where does the Five Path common group (position 4) align to?
C 10-Path transfer device
What do the CETCs do?
Measures fuel assembly COOLANT and core outlet temperatures
What temperatures are the CETCs rated for?
100°F - 2300°F
What powers the Train A CETCs?
CRID 1
What powers the Train B CETCs?
CRID 4
On the 5 path device, where does the detector go when selected to Emergency?
- Next 10 Path
Where is the MIDS storage (Position 5)?
On the containment wall
Which guide tube do we use to calibrate (position 2) the MIDs?
J-10
How do we frequently verify Hot Channel Factors during normal ops?
AFD, QPTR, Rod Insertion Limit
What is the travel path of MIDs (Inst room to Core)?
Drives => Limit Switch => 5 Path => Wyes => 10 Path => Valves => Seals => Core
CETCs have an input to which CR indications?
Subcooling Monitor Meter, PPC, Mid Loop Monitoring, and Recorders
Where do the drains for the 10 path transfer devices go?
There is a common drain and if there is a leak, it alarms in CR
How will a thermocouple fail if there is an open?
LOW
How will a thermocouple fail if thre is a short?
LOW
