Chernobyl visit with Arduino Geiger counter

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Perhaps an odd project for my site but with some friends we visited the Chernobyl exclusion zone, small town of Zalyssa, city of Pripyat (Get out of here Stalker), Chernobyl (Vladimir Ilyich Lenin) nuclear power plant and Duga 3 Over The Horizon (OTH) Radar installation receiver on the 29th of September 2019.

Alongside a certified dosimeter-radiometer (Terra-P Ecotest) and my own custom build Arduino Geiger Counter kit with GPS location and date-time logging we explored the zone.

Like for many people Chernobyl has certain lure to it and it's surrounding, that is a must see location on how technology can turn out horrible and destroy a vast area.
Luckily thanks to the sacrifice of many people from different parts of the world the zone is very slowly recovering, though this will take ages.

The zone has an eerie beauty to it, nature is reclaiming the zone ever so gradually, wildlife and dogs are flourishing.

There is even a good cause active for the "Dogs of Chernobyl" for those who are interested.
Though I believe there is a local Ukrainian cause as well, unfortunately I haven't found it.

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Left to right: Jens Van Hoecke, Laurens Gregoir and Tom Timmerman.

NB: When we visited the exclusion zone we had utmost respect for those who died there, during and after the incident. Those who fought the invisible enemy. Those who lost their homes and had to relocate.


The Geiger counter consists of

Both the SI-3BG and SBM-20 were scavenged from a defunct DP-5V probe.


The insides:

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How it works:

Behind the LCD screen rests the onboard Arduino with controls and logging capability. Instead of using the build in power supply the SBM-20 and SI-3BG tubes a powered by the High voltage driver to supply a more steady TTL signal and very stable power supply, which feeds back into the controller.

To do so the creator of the board helped me with bypassing the needed components to directly feed it into an 2N3904 transistor which connects to INT0 of the Arduino.

Each count logs the GPS location (NMEA format), date, CPM (or uSV/HR) and total absorbed amount (in uSV) to the SD card.

The end result is this neat box which fitted in my camera bag perfectly and worked like a charm, measurement against the Terra-P Ecotest dosimeter our control unit was a bit different. The counting was a bit slower, though the results were very similar!
Only a few minor differences in the readouts which were negligible.

Future projects are a 3D printed case and a roof or wall mounted GM utilizing an SI-22G that logs radiation for my region for the whole year.

Close up:

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  • First image: One of the many warning signs of the Red Forest with on the background the railroad leading to the Yanov train station with both dosimeters  featured.
  • Middle image: Close up of both dosimeters (left my custom build Geiger Counter and on the right the Terra-P from Ecotest).
  • Last image: Close up of my Geiger counter with a CPM of 224 and increasing fast.

CPM to uSV (Top 20)

For the SBM-20 I've used 0,0057 as the conversion factor.
The SI-3BG conversion factor is 0,631578.

The median was 41,5 CPMs or 0,23655 uSV/HR for most areas.
Highest counts occurred around the plant (336 CPM or 1,9152 uSV/HR) and the beginning of the Red Forest area (2227 CPM or 12,6939 uSV/HR).

Our total dose we had during our visit was 3,35 uSV (or 0,0003590697 Roentgens).
Which is below a dental X-Ray (5 uSV).


1 306 1,7442
2 315 1,7955
3 322 1,8354
4 323 1,8411
5 330 1,881
6 333 1,8981
7 336 1,9152
8 344 1,9608
9 354 2,0178
10 370 2,109
11 373 2,1261
12 405 2,3085
13 435 2,4795
14 437 2,4909
15 597 3,4029
16 779 4,4403
17 966 5,5062
18 2040 11,628
19 2119 12,0783
20 2227 12,6939
List of top 20 readings

While we walked around the zone, the first thing you notice is the silence, we didn't hear many birds, the day when we visited it also rained a bit in the morning which gave the tour an even more eerie feeling. Though wildlife is returning to the zone, the saddest part was to see litter in the zone from other visitors...

More information can be obtained from the downloadable logs below.

Interactive map with radiation in CPM and GPS route

Below you can find an interactive map that display each logging point with the CPM listed. On it you will see the route we took and which was the highest. The red forest had the highest counts as this area had the biggest hit of fallout during the incident.