Radiation Detectors
POWER RANGE NUCLEAR INSTRUMENTATION
POWER RANGE NUCLEAR INSTRUMENTATION
Three ranges are used to monitor the power level of a reactor throughout the full
range of reactor operation. The power range makes use of an uncompensated ion
chamber.
EO 3.5
STATE the reason gamma compensation is NOT
required in the power range.
EO 3.6
Given a block diagram of a typical power range
instrument, STATE the purpose of major
components.
a.
Linear amplifier
b.
Reactor protection interface
Power range nuclear instrumentation normally consists of four identical linear power level
channels which originate in eight uncompensated ion chambers. The output is a steady current
produced by the neutron flux. Uncompensated ion chambers are utilized in the power range
because gamma compensation is unnecessary; the neutron-to-gamma flux ratio is high. Having
a high neutron-to-gamma flux ratio means that the number of gammas is insignificant compared
to the number of neutrons.
The output of each power range channel is directly proportional to reactor power and typically
covers a range from 0% to 125% of full power, but varies with each reactor. The output of each
channel is displayed on a meter in terms of power level in percent of full rated power. The gain
of each instrument is adjustable which provides a means for calibrating the output. This
adjustment is normally determined by using a plant heat balance. Protective actions may be
initiated by high power level on any two channels; this is termed coincidence operation.
Rev. 0
Page 69
IC-06
