Detection device UDPN-01 is intended is intended for monitoring of thermal neutron flux density in the channels of ionization chambers at reactor plant operation in start-up (pulse more of operation of detection unit BDPN-01) and in working (current more of operation of detection unit BDPN-01) ranges.
UDPN-01 ensures monitoring of density of thermal neutron flux in initial range from 1 to 1.0·106 cm-2·s-1 (neutr.·(cm2·s)-1), in working range from 2.4·106 to 3.6·109 cm-2·s-1 at the dose rate of background gamma-radiation absorbed in the air at the place of detection unit location of not more than 1.0·104 Gy·h-1 (1.0·106 R·h-1) at nominal power of reactor plant (100 %).
UDPN-01 sensitivity for thermal neutrons in initial range is (0.5 ± 0.1) cm2 (amount of pulses during 1 s at the flux density of 1 neutron via 1 cm2 during 1 s), in working range – (1.0 ± 0.1)·10-4 cm2.
UDPN-01 (UDPN-01-01) consists of:
- Detection unit BDPN-01, implemented in the form of casing (thin-wall cylinder made of stainless steel), inside of which the chamber КNК15 is located. BDPN-01 converts neutron radiation into current pulses (at great values of neutron flux density - into current).
The appearance of detection unit BDPN-01 is presented on the picture:
- Conversion unit BPH-01, implemented in the form of flat housing, inside of which the electromagnetic shield with electronic modules is located. BPH-01 performs the following:
- amplification of current pulses received from BDPN-01;
- discrimination of noise pulses;
- generation of output pulses with the frequency proportional to neutron flux density (at UDPN-01 operation in initial range);
- conversion of current from BDPN-01 into succession of voltage pulses which frequency is proportional to neutron flux density (at UDPN-01 operation in working range).
The appearance of conversion unit BPH-01 is presented on the picture:
UDPN-01 is built-up on the basis of ionization fission chamber KNK15 with thermo-radiation stable cable with magnesia insulation (KNMMS). Length of BDPN-01 cable depends on design of detection unit.