Incore Instrumentation Flashcards
During what power range is incore instrumentation used to determine gross power distribution?
A. 0-20%
B. 20-40%
C. 20-100%
D. 80-100%
C. 20-100%
Design BASIS
The Incore Instrumentation System is designed to perform the following:
• To determine the gross power distribution in the core during different operating conditions
from 20% to 100% power.
• To provide data to estimate fuel burn-up in each fuel assembly.
• To determine data for the evaluation of thermal margins in the core.
(EO 1.1)
The incore assembly locations are each equipped with five _________ detectors and one full length
background detector.
A. palladium
B. rhodium
C. chromel-alumel
D. chromel
B. rhodium
EO 1.2
The rhodium detectors are placed axially along the movable detector calibration tube at __________.
A. 10, 30, 50, 70, and 90% of active core height
B. 0, 20, 40, 60, 80, and 100% of active core height
C. 10, 30, 50, 70, and 90% of reactor vessel height
D. 0, 30, 40, 60, 80, and 100% of reactor vessel height
A. 10, 30, 50, 70, and 90% of active core height
The rhodium detectors are placed axially along the movable detector calibration tube at 10, 30, 50, 70, and 90% of active core height.
(EO 1.2)
Explain the operation of the neutron detector associated with the Incore Instrumentation System.
The reaction is as follows:
45Rh103 + Neutron —> 45Rh104* —> (42 sec) 46Pd104 + β- + Ɣ
A negative charge is built up on the signal cable sheath (collector) due to electron surplus, while the rhodium (emitter) builds up a positive charge due to electron depletion. The electrons, which are collected by the sheath, cause a current flow, which is proportional to the incident radiation.
(EO 1.3)
What system supplies power to the in-core amplifier bin assemblies?
A. NK
B. PK
C. NN
D. PN
D. PN
Class 1E 120 VAC Power (PN) Power to the amplifier bin assemblies is from the class 1E power supplies.
(EO 1.2)
What is the temperature range of the Core Exit Thermocouples?
A. 200 - 2000°F
B. 1500 - 2300°F
C. 200 - 2300°F
D. 32 - 2000°F
The process range of the thermocouples is 200 °F to 2300 °F.
EO 1.5
What is the purpose of the background detector associated with the Incore Instrumentation System?
A. detect background
B. provide pulse height discrimination
C. provide amplification to the detector signal
D. thermalize neutrons for capture
A. detect background
Part of the overall signal generated in the incore instrumentation is not related to neutron flux at the detector, but to noise or background. In order to determine this value, a full length signal wire is run alongside the detectors to measure current produced by the wire. This signal is subtracted from the detector signal to determine true signal level.
(EO 1.4)
What are the Core Exit Thermocouples (CETs) associated with the Incore Instrumentation System made of?
A. inconel 690
B. chromel-alumel
C. stellite
D. rhodium
B. chromel-alumel
EO 1.5
Where do the Core Exit Thermocouples (CETs) associated with the Incore Instrumentation System read out?
A. QSPDS plasma display only
B. ERFDADS
C. QSPDS plasma display and QSPDS cabinet
D. QSPDS cabinent only
C. QSPDS plasma display and QSPDS cabinent
The CETs can be read on the QSPDS plasma display or the CET reading can be taken directly from the QSPDS cabinets behind the control boards
(EO 1.5)
Where are the Core Exit Thermocouples located?
A. core outlet plenum
B. a temperature controlled junction box
C. 10% of active core height
D. steam generator outlet plenum
locates the CET above the fuel alignment plate in the reactor coolant outlet plenum allowing for an accurate measure of the coolant as it exits the fuel
(EO 1.5)
