Twenty Years After, Instruments (part 10 of n)

In Chernobyl area instruments to measure radiation are popular. Most are Geiger type detectors and a lot use a classical "click, click, click..." audio warning, usually along with a numerical display.

Likely they all measured "absorbed dose" which is the easy to measure. I believe that all the instruments I saw were measuring the dose in rad/hour (the russian word for "hour" looks like "4AC", with a "4" open in the upper part as usual in "4" draw by hand - (we can see that word on photo 1).

Roentgen/Hour is a obsolete term that means more or less the same.

Photo 1: Observation room. Absorbed dose = 1.23 rad / hour (?). Probably the sensor was on the building but outside.

Photo 2: Downtown Pripyat (counter in close contact with the mud). Absorbed dose = 1.264 rad / hour (?). Out of the mud the dose halved.

Other photo of a similar intrument in the exact same spot:

http://www.neatorama.com/2006/03/29/ghost-town-chernobyl-photoblog-by-elena-filatova/


Those value are generally considered "very high radiation area" the higher possible classification when dealing with nuclear security. However those values are not particularly useful to access risk. I explain.

First, the values of the "absorbed dose" should change very rapidly from point to point, so a few "hot spots" are not dangerous if rare.

Second, the main danger comes from radionuclide we inhale for the environment and from dust we collect with our body (mainly by our hair, beard, nails), that can later irradiate our body from inside (i.e. at very close range).

Added in 2006-May-25: I think that some TV crews mistakenly took my GPS for a sort of "radiation meter" so they film it a lot :-)

UPDATE (Coordinates & Satellite Photos - added in 2006-May-31):

Photo1:

http://maps.google.com/maps?q=&t=k&om=1&ll=51.391179,30.095249&spn=0.001667,0.004989

UPDATE (added in 2006-Jun-2):

Photo2:

http://maps.google.com/maps?q=&t=k&om=0&ll=51.407652,30.055214&spn=0.004444,0.009978

Advance topics:

All the instruments I've seen measured the "radiation" in rad/hour (although they should be using the SI unit gray/second, i.e. Gy/s).

1 Gy = 1 J/kg = 1 m2·s–2 = 100 rad

Try not confuse with "dose equivalent" (in rem/hour, SI: sievert, 1 Sv = 100 rem). Of course they have the same dimensions and, in some cases, similar values.

Rem/hour are probably more useful but more difficult to measure.