Appearance of detection unit BDMG-04 (without bracket)

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The detection unit use for:

• in composition of a control radiation safety equipment (ASKRS) on nuclear power plants;

• together with standard measurement instrumentation techniques (dosimeter - radiometer MKS-2001, Multichannel analyzer for parallel counting AMP-12 "Puls 1А");

• together with the standard electronic-physical instrumentation having the conforming orifices (for reception of a sequence statistically the distributed pulses or interfacing RS-485).

The diagrammatic representation of detection unit BDMG-04 connection (1) of through a connecting box KRS-29 (2) to the measuring unit of dosimeter - radiometer MKS-2001 (3)

 

Detection unit has a built-in microcontroller which managing of its devices and had determined of gauged value. Detection unit can work in handing over regime of the information on gauged value as subsequent pulses and in handing over regime of the information on gauged value at interfacing RS-485.
 The microcontroller of the detection unit to evaluation of gauged value on a base of a gauged counting rate from Geiger-Muller counters with the count of a statistical property of allocation pulses at time. The microcontroller has linearization of a plateau counters characteristic of mathematical methods too. The microcontroller monitoring a high voltage on counters and fulfills monitoring procedures of work capacity the detection unit.

3. Preferences
1. The detection unit is fasten to a vertical surface (to a wall, a girder, a design, etc.) with help a holder. The design of the holder does ensure a possibility of fast changing  the detection unit on a plant. That is especially actually at the detection unit determination in heightened level MEqD of a gamma ray zones. Fastening of the detection unit in a holder is kind of with the help of a tilting yoke. The tilting yoke has positioned into work position with the help of a nut, which has fixed without application of the special instrument. The holder fastens on a wall with the help of expansion bolts with the screws, included in a package of detection unit delivery.
 

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2. For conveniences of detection unit wiring on a plant, the connecting box KRS-29 to be part of package delivery.
 

 Connecting box KRS-29 is ensuring of communication cables connections to spring terminal connectors without unbrazing of scutoff points on a plant.
There are set the elements in the connecting box which providing realization of requirements to electromagnetic compatibility (has ensuring normal operation of the detection unit in requirements of an electromagnetic environment of average stiffness, group of fulfillment on noise stability П3 on НП 306.5.02/3.035).
The connecting box has a demountable cover, which fastens to the cage of a box with the help of four screws.
On an interior of connecting box cover is the table of connection with notation and the name of contact pieces for connection BDMG-04 to equipments.
 

Connecting box KRS-29 has fastened on a wall with the help of screws, consisting of delivery package the detection unit.
 Connection of the detection unit to the connecting box is kind of by cable to form of KRS-29. Length of a cable – 1,5 m. At the advanced order, the length of a cable can be enlarged up to 5 m.

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3. The gaiter does protective of connection from action of external factors is positioned on a cutoff point bridging a cable of a connecting box with the detection unit.
 

4. For a possibility connection of the detection unit to anyone low-voltage direct-current power supply on plant of exploitation, the current supply of the detection unit is ensure in a wide range. The current supply of the detection unit has carried out from the direct-current power supply with a strain from +8,0V up to +42,0V. The inner transducer of a strain makes a strain +12V for a power supply the schema of the detection unit and a high voltage for a power supply of GM-tubes.

5. The detection unit can give away the information as an impulse sequence and on interfacing RS-485.

6. The broad bandwidth of measuring and presence of the detection unit modifications are allowing the optimally for select the necessary detection unit in dependence on problems and requirements of its application..

4. Modification of detection unit
The detection unit has five modifications:

 

The GM-tubes in one's capacity of the sensors had used in the detection units.
Detection units BDMG-04-02, BDMG-04-03 and BDMG-04-04 have one GM-tube. The detection units BDMG-04-00 and BDMG-04-01 have two GM-tubes. Each of GM-tubes is part of a separate measuring channel (rough and responsive for BDMG-04-00 and rough and average sensitivity for BDMG-04-01).

Outline dimensions of the detection unit modification are differing only in length

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5. Performance attributes

Service conditions of the detection unit:

• Ambient temperature from a minus 40 up to a plus 70 °С;

• Velocity of change of temperature - 10 °С/h;

• Atmospheric pressure from 54 up to 540 kPa;

• The upper value of relative humidity (75±3) % at temperature 70 °С and limiting value of relative humidity up to 100 % at temperature 50 °С.

Performance of detection unit:

• Range of logged energies of a gamma-ray from 0,05 up to 3,0 MeV.

• The gauging range MEqD of a gamma-ray is given below:

Designation	Measuring range, Sv/h	Comment
BDMG-04-00	from 0,05×10-6 to 10	Two channels: №1 (with high sensitivity GM-tubes) and №2 (with low sensitivity GM-tubes)
BDMG-04-01	from 1×10-6 to 10	Two channels: №1 (with average sensitivity GM-tubes) and №2 (with low sensitivity GM-tubes)
BDMG-04-02	from 0,05×10-6 to 2×10-3	One channel (with high sensitivity GM-tubes)
BDMG-04-03	from 0,1×10-3 to 10	One channel (with low sensitivity GM-tubes)
BDMG-04-04	from 1×10-6 to 50×10-3	One channel (with average sensitivity GM-tubes)

• Limens of a supposed base relative error of gauging MEqD of a gamma-ray at a confidence coefficient 0,95 pay off by formula:

         δHi = ± (15+ К/Ах) %,        where: Ax - gauged value MEqD, Sv/h;

             К = 1×10^-6 - for BDMG-04-00 (at MEqD less 0,1×10^-3 Sv/h) and BDMG-04-02 (at MEqD less 0,1×10^-3 Sv/h);

             К = 2×10^-6 - for BDMG-04-00 (at MEqD less from 0,1×10^-3 Sv/h up to 2×10^-3 Sv/h)  and BDMG-04-02 (at MEqD from 0,1×10^-3 Sv/h);

К = 2×10^-5 - for BDMG-04-01 (at MEqD up to 20×10^-3 ) and BDMG-04-04;

К = 2×10^-3 - for BDMG-04-00 (at MEqD more 2×10^-3 Sv/h), BDMG-04-01  (at MEqD more 20×10^-3 Sv/h) and BDMG-04-03).

• Power dependence of detection unit sensitivity to concerning power 662 keV gamma-rays of radioactive nuclide 137Cs over the range energies from 0,05 up to 0,66 MeV is in limens from a minus of 25 % up to a plus of 25 %, over the range energies from 0,66 up to 1,25 MeV - from a minus of 25 % up to a plus of 40 %.

• Stabilization time of an operating mode of the detection unit no more than 2 minutes.

• Time of continuous operation of the detection unit not less than 24 h in a day.

• Instability of detection unit indications during continuous operation 24 h no more than 5 %.

• The detection unit are stable against action of a gamma-ray with absorbed dose rate of a gamma-ray up to 1,5×10^-4 Gray/h.

• The design and coating materials of the detection unit is ensuring a possibility of carrying out of a decontamination (are stable against machining the cage by a napkin, the wetted one of deactivating solutions of composition 5, 8, 9 or 10, the application 3 GOST 29075).
  - Oxalic (or citric) an acid - 10 g / dm³;
  - 5 % solution of a citric acid in alcohol С2Н5ОН (firmness of 96 %) - for intrinsic surfaces;
  - Fumaroles acid - 16 g / dm³, Na2S2O3 × 5H2O - 1 % solution;
  - Synthetic scours such as "News", ОП-7, ОП-10;

• The detection unit is falling into to recovered equipment of the long-lived use.

• The averages mean lifetime of the detection unit not less than 25000 h provided that the radiation resource of the GM-tubes will not be exceed.

• The average life cycle of the detection unit, not less than 10 years consideration of changing of separate modules and the clusters which working out the resource.

• The average time of a up state regeneration of the detection unit at use of reserve parts from composition spare parts no more than 2 h.

Overall dimensions and  weight of the component parts
 

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