SPC Doza

124460, Russia, Moscow, Zelenograd, Avenue 4806, Ltd. 6


Radiometric unit UDI-1B: radioiodine monitor



  • measurement of volumetric activity of radionuclides I-131, I-132, I-133, I-135 in the air

An example of spectrum acquired using the UDI-1B unit


  • built-in air flow meter
  • performance self-test by means of Am-241 check source implanted into the detector
  • gamma background rejection capability
  • interfaces RS-232, RS-485, Ethernet
  • audible and visual alarm signals of the excess of preset thresholds
  • UDA-1AB can either operate its own pump unit or use the external air sampling line
  • setting up with the help of a notebook or any mobile computer
  • periodic in-situ verification (testing, calibration) by means of working standard
  • “dry contact” output
  • connection of the external alarm signaling unit of “BAS” type
Principle of operation:

Principle of operation is based on processing of energy spectra of gamma radiation from radionuclides deposited (absorbed) on the sorption material of the filter during air pumping through it.

The UDI-1B simultaneously measures the volumetric activity of radioactive iodine isotopes according to both accumulation algorithm (i.e. accumulated over specified period of time) and the monitoring algorithm (i.e. instantaneous values).

Basic complete set:

  • UDI-1B unit
  • cable RS-232 for communication with computer
  • check source with holder
  • software for verification and adjustment
  • operation manual and passport
  • radioiodine collection filter cartridges – 6 items
  • sample trap

By request:

  • adapter hose for measurements of the air in the air discharge (ventilation) systems
  • pump unit BN-01
Description of the unit and its parts:
The display shows system status, measured values and diagnostic information
The unit is equipped with RS-232 port and Ethernet IEEE 802.3 or RS-485 interface. RS-232 is intended for servicing of the unit using the “Cofigurator” software (for control, testing, adjusting and repair purposes), while RS-485 and Ethernet IEEE 802.3 are external interfaces that serves for integrating of the unit into radiation monitoring systems. A device connected to the “dry contact” output of the unit UDA-1AB, can be switched ON or OFF in case that the threshold is exceeded. The external alarm control unit is connected to the BAS connector. The UDA-1AB controls its own pumping unit or, alternatively, is able to control, by energizing the “PUMP” power connector (220 V, 50Hz), the external execution units (e.g. electromagnetic valves while operating with the external air sampling line)
The “Configurator” software is intended for control, testing, adjusting and repair of the UDA-1AB and also allows the operator to receive and view measurement data from the unit’s archive
The sample trap accommodates a cartridge with sorption material. The cartridge should be replaced by a fresh one when a warning about sorbent contamination appears on the LCD screen and corresponding message is sent by the UDI-1B to the information network. This occurs when the activity of any given iodine isotops is greater than 1•104 Bq in the “Filter” measurement mode. Anyway, the cartridge should be replaced at least quarterly
For tests of performance and energy calibration, the Na-22 a reference source is used. This reference source with activity 10?15 kBq (installed in the holder) is delivered with the UDI-1B
The reference source provides simultaneous testing of both the measuring channel and the background channel
Periodic verification of the UDI-1B unit is performed using working standards – sample traps filled with solid state granular reference sources (Cs-137 and Co-60)
Technical characteristics
Detectorsscintillation detectors CsI(Tl)
Number of detectors2 (for measurement and for compensation of background)
Measurement range:
in the accumulation mode, over 6 hours0.1÷105 Bq/m3
in the monitoring mode3.71÷3.7·108 Bq/m3
Energy range60÷3000 keV
Maximum level of external background gamma dose rate for which compensation is valid10 µSv/h
Intrinsic background of the unitno more than 3.7 Bq/m3
Measurement intervalnot more than 1000 seconds (for monitoring mode, interval is inversely proportional to the activity)
Volume throughput through the collection cartridge20÷40 l/min
Air volume measurement errorless than±10 %
Archive of measurement results in the built-in memory3000 records
Operation temperature rangeminus 10 °C÷+50 °C
Overall dimensions, weight448×323×479 mm, 35 kg
Power supplymains 220 (-15 %; +10 %) V, 50 Hz (±5 %)
Power consumptionnot more than 50 VA
Replacement life of sorption material under continuous operationnot less than 2000 hours
MTBF10000 hours
Atmosphere typeI, II, III, IV according to GOST 15150-69 (the State Standard of the Russian Federation)
Operation relative humidityup to 98 % at +35 °C
Seismic stabilitythe unit complies with the requirements of NP-031-01 and RD 25-818* for seismic disturbances up to earthquake intensity 7 on the MSK-64 scale for 30 m level above ground level
Electromagnetic compatibilitythe unit is classified as group III device, operation criterion A according to GOST R 50746-2000 (the State Standard of the Russian Federation)
Ingress protectionIP23
UDI-1B is considered an element of the system intended for NPP normal operation as defined in the Safety Rules “OPB-87/99” (applicable safety class: 3N).

*NP-031-01 “Design code for earthquake-resistant nuclear power plants” and RD 25-818 “Regulations. General requirements and testing procedures of the seismic stability of instruments and automation equipment supplied for the nuclear power plants” are regulations of the Russian Federation

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