INTERMEDIATE RANGE NUCLEAR INSTRUMENTATION
Radiation Detectors
INTERMEDIATE RANGE NUCLEAR INSTRUMENTATION
Three ranges are used to monitor the power level of a reactor throughout the full
range of reactor operation. The intermediate range makes use of a compensated
ion chamber.
EO 3.4
Given a block diagram of a typical intermediate
range instrument, STATE the purpose of major
components.
a.
Log n amplifier
b.
Differentiator
c.
Reactor protection interface
Intermediate-range nuclear instrumentation consists of a minimum of two redundant channels.
Each of these channels is made up of a boron-lined or boron gas-filled compensated ion chamber
and associated signal measuring equipment of which the output is a steady current produced by
the neutron flux.
The compensated ion chamber is utilized in the intermediate range because the current output is
proportional to the relatively stable neutron flux, and it compensates for signals from gamma
flux. This range of indication also provides a measure of the rate of change of neutron level.
This rate of change is displayed on meters in terms of startup rate in decades per minute (-1 to
+10 decades per minute). High startup rate on either channel may initiate a protective action.
This protective action may be in the form of a control rod withdrawal inhibit and alarm, or a high
startup rate reactor trip.
IC-06
Page 66
Rev. 0
