SOURCE RANGE NUCLEAR INSTRUMENTATION
The logarithmic count rate signal is differentiated to measure the rate of change in neutron flux.
The differentiator output is proportional to reactor period. The value of reactor period is
inversely proportional to the actual rate of change of reactor power and relates to power changes
by factors of e (2.718). The power rate change based on factors of 10, in decades per minute,
is more meaningful to the reactor operator. Therefore, the output of the differentiator is
converted from reactor period to decades per minute through the meter scale used.
The purposes of source range components are summarized below.
Source Range Instrumentation Summary
The linear amplifier amplifies the input signal by a factor of several thousand
to raise the pulse height to several volts.
The discriminator excludes passage of pulses that are less than a predetermined
The pulse integrator provides an output signal proportional to the logarithm of
the count rate.
The log count rate amplifier amplifies the signal for display on a meter.
The differentiator provides an output signal proportional to the rate of power