Beta-radiometer SZB-04
Keep your hands clean

Many of those who have been with us at Chernobyl power plant, asked — what are these grey boxes? You may find them installed in the Golden corridor that connects all the reactor units.

These are the threshold-operating radiometers of beta-contamination SZB-04, designed for quick check-up of surfaces and body parts. They are Soviet made, but due to simple design, high reliability and, the most important, increased sensitivity are still in wide use across power plants. In our lab we have a SZB-04 from 1987.

The device consists of a detection block BDB2-02-I2 (БДБ2-02-И2) and a control panel that can be placed on a table or mounted on a wall:

Beta-radiometer SZB-04

A detection block is based on two Geiger-Muller detectors SBT-10A (СБТ-10А) designed to register a soft β-emission. They are placed in a sturdy enclosure with a retractable handle, so it is possible to mount the detection block on some surface or to hold it in hand conveniently. As surface of this counters is quite gentle as it is made from micanite, it is additionally protected with a moveable metal lid, mechanically connected with a rugged button releasing of which initiates the counting process. Therefore, it is possible to make an automatic outpost to check contamination of hands — you place your hand firmly, thus releasing the button, and then wait for result.

Beta-radiometer SZB-04 Beta-radiometer SZB-04

A control panel is equipped with two large indicators — green and red, as well as analog nixie tube that displays approximate intensity of the beta-flux. During measuring, impulses, that come from a detection block are being converted to voltage by channels of counting and ambience, then checked by a differential amplifier and then transmitted to a threshold block. A logic board, depending on a signal from the threshold block, switches green or red indicator, signalizing that contamination is within permitted limits or not, respectively. Additionally, it is possible to connect an external alarm device (a bell, siren or some warning light) using a rugged connector on the rear side of the control panel. It is possible to adjust the sensitivity using the knob. When you adjust it to a minimal position, a device will react even on background radiation.

Beta-radiometer SZB-04 Beta-radiometer SZB-04

Beta-radiometer SZB-04
A nixie tube below green and red signal lamps shows the beta-flux.

Beta-radiometer SZB-04
An example of a warning indication.

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