Wide Range Analog Module
The detector is a fission chamber (recommended CFUL 08 for out-of-core applications) for detection of thermal neutrons in a flux range of 1 to 2*1010 nv. The same detector probe is used for the pulse (sensitivity 1 pps/nv), and variance (sensitivity 4*10-26 A2/Hz/nv) measurement. The Wide Range Analog Module RNL-04.01 is located in a double shielded box near to the detector (max. 8 m) but out of the reactor vessel. The signal of the fission chamber gets to the input of the preamplifier. The transformer coupling at both input and output allows for ground isolation. It amplifies the measuring signal obtained from fission chamber and splits it into pulse and AC components. These signals are separately amplified in the pulse and AC1 amplifiers. The function of the preamplifier with two remote controllable test generators (TG0) can be checked from the neutron flux computer.
The AC1 amplifier has a divider (AC-signal division by 1 or 100) which is used to build together with the programmable divider the 16 linear fractions. The signal from the AC1 amplifier is conducted through an eight-step signal attenuator (0…7*5 dB) with measuring range commutation switch to the AC2 main amplifier. The measuring range control should be performed through 3 binary code lines (2^2, 2^1, 2^0 The input of the step divider can be switched over to the output of TG2 test generator by remote controlled binary signal (0,5 V/25 kHz). The amplitude of TG2 test generator can be adjusted by potentiometer. The correlator performs the squaring and smoothing of the alternating signal. Output signal of correlator is led through the isolated driver to the AC SIGNAL OUTPUT connector and via V/f converter and isolated line driver to the neutron flux computer. The AC range overlaps at its lower end with the pulse range more than one decade.
The pulse signal is processed in an amplifier with amplitude discrimination. The amplitude discriminator converts the incoming detector pulses into standard pulses, if the threshold voltage of the discriminator exceeded. The adjustable discriminator suppresses background signals induced in the cable, electronic noise, and a radiation. This pulse signal will be processed in the range of 10-1 pps to 106 pps. The pulse frequency predivider serves to purpose of minimizing the statistical double pulse and dead time error. The ÷16 FREQ. DIVIDER controls the divider. Threshold level can be controlled from DISCR LEVEL CONTR current-loop input, and can be monitoring from MON DISCR LEVEL current loop output. The input of the integral discriminator can be switched over to the output of TG1 test generator by remote controlled binary signal (TEST ON TG1). The two possible test frequency of TG1 test generator can be selected by binary signal (TG1 1,563/500 kHz).
The high voltage stage generates the adjustable HV (0 to 800 V) required for the fission chamber. The HV power supply is surrounded by current-loop driven isolated set-value controls and HV-monitoring isolation amplifiers. Set-value control signal from HV CNTR is current-loop input, monitoring signal from HV MON leave the board in the form of current loop output.
The 24 V DC power supply is provided from NF. It enters the board through transient protection fuse diode. The unit also contains an isolation amplifier-current loop function to get the primary power monitoring signal (MON POWER S) output.
Main Technical Data