Pulse Assembly for Reactor Control

This assembly is connected to pulse neutron detectors: fission chamber, BF3 counter, boron counter. No preamplifier is needed. The input impedance of the amplifier is matched to the impedance of the coaxial cable connected to the detector. The assembly can work with a length of cable between the detector and the electronics as long as 200 meters. The effects of reducing the electrical interferences on the cable and on the assembly have been studied and the results of the tests done near different reactors are given. The current collection mode is used. The useful range of the assembly is limited by the collection time of the detectors and it allows a maximum range of 5.106 c/s with an accuracy of 10%, taking in account statistical fluctuations. The description of the electronic circuits of the assembly is given: amplifier, d.c. level restoring circuit, discriminator. It is possible to use the two outputs of the assembly in digital mode (calibrated pulses) and in analog mode (d.c. current proportional to the counts per second: 10-11 A/C) and so a digital or an analog rate meter can be used. The assembly is built with 6 modular blocks: transformer, low voltage d.c. supply, high voltage supply, pulse amplifier, discriminator and tests.