АТ2331 Emergency Alarm Dosimeter

АТ2331 Emergency Alarm Dosimeter is designed for detection of self-sustaining chain reaction and generation of sound and light alarm signals to evacuate personnel from hazardous area.


Аlarm dosimeter is a fixed design package consisting of gamma radiation detection units, processing and alarm units for on-site installation.

Alarm dosimeter operation principle is based on gamma dose rate measurement by BDKG unit, results matching with pre-set threshold levels "2 from 3"/"OR" logic processing of BDKG unit signals about exceeded alarm threshold levels to generate alarm signal to indicate self-sustaining chain reaction condition.

Instrument can accept data about two dose rate measurement threshold levels and store it for further use when alarm dosimeter is powered on.
АТ2331 Alarm dosimeter can be connected to АТ2327 Alarm dosimeter or personal computer using "SARK2" software to create an emergency alarm system. 
Up to 3 alarm dosimeters can be connected to АТ2327 and up to 32 alarm dosimeters – to PC.
When AT2331 Alarm dosimeter is a part of emergency alarm system, operating one alarm dosimeter triggers all alarm dosimeters of the system.
The sound mute switch can be used to deactivate audible alarm after personnel evacuation.

If malfunction of one unit from emergency alarm dosimeter or communication line occurs, the rest of the units will continue operating in stand-alone mode preserving all detection, alarm, measurement and data storage functions.


Safety assurance for staff of companies utilizing, processing and storing fission materials


Detection of self-sustaining chain reaction in full range of its characteristics
Smart probes
Long operation life
High reliability
Self-monitoring of component parts
Backup power supply unit
Writing and storing measurement results in non-volatile memory of alarm dosimeter
Automatic monitoring of battery level

AТ2331 Emergency alarm dosimeter as part of emergency alarm system complies with requirements of "Design and operation industry regulations on alarm systems for occurrence of self-supporting chain reaction and on arrangement of consequence restriction measures" ПБЯ-06-10-99 and takes into account International Electrotechnical Commission IEC-860 (1987) recommendations and regulatory requirements of US Standard ANSI/ANS-8.3 Criticality Accident Resources and Information Alarm System (1986).

AТ2331 Emergency alarm dosimeter complies with fire safety code GOST 12.1.004-91, electrical safety requirements GOST 12.2.091-2002 and electromagnetic compatibility requirements: STB IEC 61000-4-2-2011, STB IEC 61000-4-3-2009, STB IEC 61000-4-4-2006, STB IEC 61000-4-5-2006, STB IEC 61000-4-6-2011, STB IEC 61000-4-8-2011, STB IEC 61000-4-11-2006.


Minimum duration of the registered self-sustaining chain reaction

1 ms

Measurement range of gamma and x-ray radiation absorbed dose rate

0.1 µGy/h ... 1 Gy/h

Measurement range of gamma and x-ray radiation absorbed dose rate

0.05 µGy ... 10 Gy

Limits of tolerable intrinsic relative error of measurement


- For dose rate measurement


- For dose measurement


Energy dependence relative to 662 keV (137Cs)

±35% (in 60 keV – 3 MeV energy range)

Measurement time of x-ray and gamma radiation dose rate (1 µGy/h) with maximum statistical error 20%

≤120 s

Time to alarm operation under exposure to radiation dose and/or dose rate equal to double threshold value

≤300 ms

Alarm sound level at 1-meter distance

100 dB

Maximum distance of communication line between alarm dosimeter components to maintain operation

≤1000 m

Initialisation time

≤5 min

Power supply

230 VAC 50 Hz mains or 24 VDC battery in case of mains power failure

Continuous run time

24 h with AC mains power supply; ≥6 h in case of self-contained operation from fully charged battery

Burn-up life

≥100 Gy

Mean operating life

≥20 years

Mean time to failure

≥15.000 h

Protection rating


- For BDKG-25, terminal-block boxes and switches

IP 57

- For other components

IP 50

Operation temperature range


- For BDKG-25, AT910, switches and terminal-block boxes

-40°C ... +50°C

- For other components

+5°C ... +40°C

Relative air humidity


- For detection units, switches and terminal-block boxes (With air temperature ≤35°C without moisture condensation)


- For other components (With air temperature ≤30°С without moisture condensation)


Dimensions and weight of components:


BDKG-25 Detection unit

Ø61х210 mm; 0.6 kg

АТ910 Recording unit

260х180х90 mm; 0.7 kg

At991c Alarm unit

185х105х98 mm; 0.4 kg

At993 Sound unit

126х124х95 mm; 0.35 kg

Terminal-block box

135х124х55 mm; 0.3 kg


135х124х55 mm; 0.3 kg

АТ980 Control unit (Without batteries) [From АТ2327 delivery package]

400х300х150 mm; 7.8 kg

Data display [From АТ2327 delivery package]

643x97x67 mm; 4.0 kg

BDKG-25 Gamma radiation detection units (3 units)
АТ910 Recording unit
AT991s Alarm unit
AT993 Sound unit
Interface adapter (RS485/USB)
Set of switches and terminal-block boxes
Mounting brackets
Calibration accessories
User's manual

Download brochure469.94 KB