Chernobyl's Cesium-137 in Nature.

[Vit Ladanyi]

Hello,

I would like to present a selection of my measurements of Cs-137 in nature. I took the liberty to use my older presentation, which I wrote for an English exam. Since the presentation without words is useless, I slightly modified the original text and attach it (Comment) to read for those interested. Substantial informations are available from slide 5 (details in the text). Please take into account that calculated surface activity (as) of 137Cs is maximal activity, but the real activity is probably lower due to geometry (smaller spatial angle) of calibration standards of surface activity of 137Cs. I apologize for any grammatical errors.

Vit

[Taray]

Good presentation.
On a similar topic ,heavy bauxite mining in Kuantan Malaysia is causing a Crimson Tide in the sea waters there.I am not staying nearby.Otherwise I would have taken a Marinelli beaker of seawater for gamma spectrometry.May pick some thorium I guess
Taray.

[brehwens]

Hi Vit

I was also surprised in my efforts to detect Chernobyl fallout here in Sweden. We were hit relatively hard in some areas due to the wind and some rain. My efforts are directed towards quantifying the Cs-137 contents in soil using Gamma spectacular-based equipment and a good lead castle.

I have some posts on this, but I have been quite inactive during the fall due to relocating, new job, and living with my inlaws. But I am now slowly starting up again, now when I am in place in my new house.

/Karl

[Vit Ladanyi]

Hi Karl,

I know Sweden was contaminated much more than Czechoslovakia. I am interested in your measurements since I am interested in radioecology. I measured only one sample of soil from the most contaminated area in "Mosty u Jablunkova" village. But it was without shielding and I found mass activity around 320 Bq/kg. I do not know if this activity corresponds to ca 49 kBq/m2, what I calculated for this area (it could be somehow calculated). Thus contaminated place was quite small, a few tens square decimeters, what was interesting. The surface activity was lower in the surrounding areas (a few tens square meters ca 33 kBq/m2) and 200 m away from there was surface activity only about 7 kBq/m2. This was due to uneven rainfall.

I measured several samples of mushrooms from Czech Republic (in lead shielding) and calibrated the RS-220 gamma spectrometer (calibration standard prepared from liquid standard of Cs-137 in radiochemical laboratory) so I calculated their mass activities. In a few samples I found interesting values but not too high.

Vit

[brehwens]

Hi Vit

From my contacts in the swedish radiation safety authority, I have learned that the quantification of Cs137 in soil is tricky because the fallout is quite heterogenous; you measure in one spot and then in another close by, and you can have a big difference....

My measurements so far are in the 2300 Bq/kg range, some samples are moss from a street gutter so I have no activity/area measurement. I will try to be more precise when sampling in the future, so I sample a certain area...

[Vit Ladanyi]

Hi Karl,

thank you for informations. Sure, the fallout was quite heterogenous due to the weather during transition of contaminated air masses.

For those who are interested in radiation monitoring I attach a link of "Radiation Situation Monitoring" webpage where are various data of radionuclides in mushrooms, forest berries, actual "Photon Dose Equivalent Rate" presented. These data are available on webpage of Czech "State Office for Nuclear Safety". http://www.sujb.cz/en/radiation-situation-monitoring/

[Alain]

Hello Vit and Karl!

I'm quite fresh member here and I don't know if this topic is still active or not (almost three years since the last post), but I will do my best to "blow the fire again from the embers in the ash". I'm quite surprised that more vivid discussion didn't took place here, because Cs-137 in Europe can be one of the most interesting and rewarding theme for every spectrometry enthusiast in EU. Well, everybody has its own interests.
Vital, great presentation, thank you for sharing:) In our highschool we also did some field research (and still doing) an I will try to post abstracts or presentations here, but first I have to translate them in English.

In our country there are some areas, which were badly hit with Chernobyl deposition. Thankfuly, they are just narrow areas in remote alpine regions with no inhabitants. But luckily, they are not far from me :)
At place where I live, specific activity of topsoil is around 130 Bq/kg for Cs-137. So nothing to wory, but easily detectable with gamma spectroscope. But mushrooms, oh boy, they are hungry for it! Not far from me, in mountain regions, I found three species of mushroms, which are extremely addicted to it: maximal activity was over 70 000 Bq/kg (or 70 kBq/kg) of dried mushroom (that would correspond to about 7-10 kBq/kg fresh mushroom and for comparison, legal trade limit is 600 Bq/kg of fresh food in EU for Cs-137). Unbelievable! You can detect radiation in dried mushrooms even with Geiger counter, although this is quite "insensitive" instrument compared to scintillation detector. I've made a couple of check sources and calibration standards for my spectrometer from those mushrooms (just dried and grinded, ready for delicious soup :P, thus spared some money and legal issues if I would order a similar check source on the internet. And right now it comes high season when those mushrooms grows. "Radguys", welcome to Slovenia! (Ups, I hope turism workers would not sue me for making a bad commercial for our country;)

And here comes the "cookie", I saved the best for last: in alpine region I found some hotspots, the highest with 100 kBq/kg (yes, 100 000) specific activity of Cs-137 in topsoil. It's already a serious matter here, no joke. For legal posession of such material (over 100 g) you already need official approvals and documents (in Slovenia we have the harshest laws on nuclear and radiation regulatory in the world).

I hope a fire is burning again, I will try to post more interesting findings about Cs-137 in environment in the future. As I said - I'm newbie here.

Regards,
Alain

[Alain]

By the way, did you know, that you can buy a Cs-137 in almost every store in EU for a couple € and made convenient energy calibration standard for a home spectrometer in a glance? Our praised "golden standard", Cs-137, to calibrate and check resolution of our detectors... I'm talking about frozen blueberies, which can be bought in a very known market chain and "the right" blueberies comes only from two EU countries (not Slovenia;). Of course, I will not publicly disclose such sensitive details (contact me on PM, if you wish to know). Legaly, everything is OK, because they contain about 300 Bq/kg (fresh matter) of Cs-137, which is "only" 50 % of legal trade limit for food in EU. If you dry them in an oven (for example for making a tea when you get ill, no bad intentions;), you get around 2000 Bq/kg (dry matter). Than you can grind them and pack a whole bag of blueberies just in one small plastic cup, ready for our spectrometer (ups, for making a tea). Detection of souch source and getting 32 and 662 keV lines (plus bonus 1461 keV from K-40, for free=) is then only a piece of cake, even without shield.

Homer Simpson would smash it in a minute, to find his way home at night :P

Regards,
Alen