# Two- Chamber Unit for Detecting Parameters in the Neutron Flux

O. A. Kuchmagra, G. I. Odynokin

Institute for Safety Problems of Nuclear Power Plants,
NAS of Ukraine, 36a, Kirova st., Chornobyl, 07270, Ukraine

DOI: doi.org/10.31717/2311-8253.22.1.4

### Abstract

The detection unit contains two neutron detectors — fission chambers KNT-31 or KNT 31–1, in which the radiator sensitive to neutron radiation is 235U (concentration of 235U in the radiator is more than 90%). The detection unit also includes two radiation- resistant preamplifiers (primary electronic equipment), which are connected to the cable transmission line to the secondary equipment, which captures the moment of pulses from the reaction of neutrons with the fission chamber radiator and save information about the time of these pulses. Further processing of the intervals between neutron events (intervals between pulses) can be done according to individual methods of the experimenter. The presence of a data processing unit type B-471 significantly expands the capabilities of the experimenter on the conclusions of statistical analysis of data and forecasting the development of emergencies in fuel-containing materials of the Shelter object. The presence of time intervals in the nanosecond range of values with sufficient probability can be classified as pulses of registration of instantaneous fission neutrons, and a change in their number may indicate a change in the effective multiplication factor of fuel containing materials. The analysis of the statistical properties of the flow of neutron event recording intervals by the electronic equipment makes it possible to predict the occurrence of a self-sustaining chain reaction. This is the main task of the Shelter object nuclear safety system. The proposed configuration of the CPI is promising and can be expanded by the number of fission chambers and electronic neutron detection units for more accurate diagnosis and prediction of the state of fissile nuclear materials.

Keywords: information- measuring channel, neutron flux parameters, two-chamber block detection, time intervals between pulses.

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Published
2022-06-30

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