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Archive 1

Confusion?

What does the following mean: "The photon energy of Ba-137m is 662 keV"? Is that to say that when Cs decays a photon is emitted and it has aforementioned energy? --Master Bob 03:36, 24 September 2007 (UTC)

Half life inconsistency

There are two tables/diagrams associated with this article (and with the main cesium article as well), that give different values for the half-life of Cs 137, namely 30.07a (in the diagram) and 30.23y (in the table). According to NIST (and CDC), the correct value is 30.17y. I'm hoping someone will fix the tables/diagrams. MeanStandev (talk) 22:06, 13 March 2011 (UTC)

Requested move

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

'No consensus to move. Vegaswikian (talk) 22:32, 11 April 2011 (UTC)

Caesium-137 → Cesium-137 — 19:17, 4 April 2011 (UTC)

Because it hasn't been 7 days yet.--RaptorHunter (talk) 16:08, 9 April 2011 (UTC)
Soon, soon... Lanthanum-138 (talk) 03:13, 10 April 2011 (UTC)
And you are not exactly being as civil as we'd like here. Lanthanum-138 (talk) 03:20, 10 April 2011 (UTC)
The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.


Image confusion

I insist that the decay scheme image is misleading. The 85,1% is the TOTAL probability of a 0.662 photon to be born out of 1 Bq of Cs-137. The probability of Ba-137m to produce a 0.662 photon is 89.9% NOT 85.1% (see http://www.nndc.bnl.gov/chart/decaysearchdirect.jsp?nuc=137BA&unc=nds) —Preceding unsigned comment added by 212.46.23.10 (talk) 06:30, 30 March 2011 (UTC) That was posted by me, sorry, didnt log on (Theolos)


Look at the cited source article. http://www.springerlink.com/content/rm0v8727k2j02x85/, If the entire figure had been copied, it would be less confusing. —Preceding unsigned comment added by 198.253.49.6 (talk) 17:16, 23 May 2011 (UTC)

The link leads to the first page of the book, no image in caesium at all. I would edit this image but i just dont know how to =) — Preceding unsigned comment added by 212.46.23.10 (talk) 10:17, 22 March 2012 (UTC)

It comes from dark asteroids (or something like that)

I'm having two problems here. First is the "the human race is evil" statement

"Unlike most other radioisotopes, caesium-137 is not produced from its non-radioactive isotope but from uranium,[7] meaning that until now, it has not occurred on Earth for billions of years."

If it comes from uranium, and uranium has been here for billions of years, this statement is confused and confusing. Surface production (above-ground), large-scale production is surely a recent thing. But if uranium has not just appeared from nowhere, then caesium has also been around in small quantities.

But then I'm having doubts about the "comes from uranium" thing. The table of parents and children seems to be telling me caesium is a fission product of plutonium. Is that correct? Of course, the large amount of plutonium is a recent thing and it is produced from uranium, and so we come back to maybe what the initial statement was trying to say?

Can somebody make that statement a bit more precise? Like "via man-made plutonium"? 24.28.17.231 (talk) 23:02, 14 November 2011 (UTC)


8% fission products from 235U fission leads to Cs-137. Perhaps contribution from Pu chain is higher. Basroil (talk) 08:55, 27 June 2012 (UTC)

Spelling

Google search results
caesium cesium
all 809,000 21,140,000
.uk 20,700 14,400
.ca 2,260 16,100
.au 13,100 4,500
.in 1,140 2,450
.ie 3,180 544
.nz 769 661
.fr 7,130 32,800
.jp 11,400 28,700

--JWB (talk) 04:22, 24 February 2010 (UTC)

WP:CAES. Lanthanum-138 (talk) 03:22, 10 April 2011 (UTC)

No kidding, so why are all COMMON spellings of terms with world-wide usage being slammed into one of the least common spellings? Isn't there a page to adjudicate this and reverse this decided single-sidedly myopic nationalization of quite common INTERNATIONAL words? 23:07, 26 October 2013 (UTC)

Sourcing

This article seems to lack adequate sourcing. Where did the information that 500 g of Caesium fell on Germany come from? — Preceding unsigned comment added by Ottawakismet (talk • contribs) 06:49, 22 March 2011 (UTC)

Cite note number 2 also seems to be dead. — Preceding unsigned comment added by Augustwollter (talk • contribs) 16:26, 11 November 2015 (UTC)

The use of Becquerel

One unreferenced section refers to Bq in Bq per meter^2. However traditionally this is given as Bq per gram. The problem with Bq per meter square is it represents a conversion from CPM based on surface measurements (probably gamma from barium decay). Bq meter square is only accurate at the moment radioactivity 'dusts' the earth surface. Cesium is water soluble to some degree (particularly in acidic solutions) and ends up going quickly into the soil, were soil particles absorb the radiation. The best way to test for cesium is to measure levels at different layers in columns of soil, estimate the Bq per gram (and confirmed with chemistry or mass spec.) Alternatively it can be measured in fluids (such as in a stock tank). This can be converted to Bq that passed the horizon per meter squared, but this is not what the article said. Nor was it mentioned how the average was obtained. The total mass can be estimated at Na x M x ln(2) / (Ma x half-life in seconds).PB666 yap 22:14, 14 November 2011 (UTC)


There is a phrase that certain meat "was found to have 1,530 to 3,200 becquerels per kilogram of Cs-137, " which seems to me clumsy or even incorrect. I dislike the idea of "becquerels of Cs-137" but even so it would be better as "was found to have 1,530 to 3,200 becquerels of Cs-137 per kilogram ," The number of becquerels per kg of Cs-137 is surely a constant. It is of course correctly becquerels of radiation from CS-137. — Preceding unsigned comment added by ‎DaveyHume (talk • contribs) 04:34, 9 January 2016 (UTC)

Has Cs-137 really not been produced naturally for billions of years?

I think we can all agree that Uranium 235 is about 0.7% of uranium deposits and approximately 44000 tons of U235 would be present in the $260 mine-able uranium ore totaling 6.3 million tons.

The spontaneous fission rate for U235 is about .5e-5 per gram per second based on information here on Wiki (with sources). The percent fission product is about 8% Cs137 for fission of U235 (likewise). Following the calculations to their end, 19kg of Cs137 is being produced every second, spread throughout the world's uranium deposits. Given the amount of U235 not in deposits, occasional neutron bombardment from adjacent spontaneous fission, and other factors, the amount would be higher.

Unfortunately, not much on the topic of spontaneous fission is available. Perhaps because it is so hard to observe. Basroil (talk) 09:19, 27 June 2012 (UTC)

It's technically produced, but in such negligible amounts (yield per decay from 238
U
: ~3E-08 (SF fraction from ICRP-07, product yield from ENDF-349)) that any you find in the field can safely be assumed to be anthropogenic. Kolbasz (talk) 12:40, 28 June 2012 (UTC)


On account of that technicality, the phrase "meaning that until now, it has not occurred on Earth for billions of years" should be changed to "meaning that until now, it has not been produced on Earth in significant concentrations for billions of years" or similar. To say that it has not occurred at all would be beyond misleading, but to say any significant (measurable) amounts are man-made would minimize bias introduced by the current wording.Basroil (talk) 00:51, 4 July 2012 (UTC)

I disagree that it would be "beyond misleading"; it would not be misleading at all. What I think is misleading would be to emphasize a nucleosynthetic reaction that is too rare to notable. There is entirely too much of this sort of pedantry in Wikipedia articles having to do with nuclear physics that gives undue weight to essentially non-existent reactions. Rwflammang (talk) 11:04, 4 July 2012 (UTC)
Am I seeing WP:OR? Sorry, but without sources, I will delete the claim: any significant (measurable) amounts are man-made. Before the atomic era, Cs-137 has been searched in the environment? No. So what? Instead read Radioactive Cs capture in the early solar system --Robertiki (talk) 01:12, 21 January 2016 (UTC)
So, I read it... I have no idea what you think the paper is saying, but it has absolutely nothing to do with the discussion at hand (except reiterating that all the primordial Cs radionuclides decayed away billions of year ago). Kolbasz (talk) 08:54, 21 January 2016 (UTC)
The paper recalls the Oklo site Cs-137. And decay never means down to zero. What about the Technetium case ? And, would you accept Caesium-137 in the environment is mostly , as my proposal of some days ago ? And negligible for the natural presence ? --Robertiki (talk) 04:20, 24 January 2016 (UTC)
I have found here that (page 4): "For 137-Cs, the highest activity concentration was found in location 4 (Edea) while it was not detectable in location 3 (Douala). This higher presence of 137Cs in locations 7, 1 and especially 4 may be attributed to the natural reactor in Oklo." The authors think to be still able to measure Cs-137 from that long time ago ? --Robertiki (talk) 03:53, 25 January 2016 (UTC)
The authors may think so, but they are wrong. There can be no Cs-137 from Oklo left. None. Zilch. Not a single atom, as Oklo was over 50 million half-lives ago (for reference, every single atom in a full tonne of Cs-137 would decay away in less than 100 half-lives). I wondered how on Earth that kind of speculation managed to get published, and then saw that it was published by Scientific Research Publishing, possibly the most infamous predatory publisher in existence. So that article is worth less than the paper it isn't printed on as a PDF. Kolbasz (talk) 01:38, 31 January 2016 (UTC)

Presence of Cs-137 before the atomic era

Cs-137 was present on earth before atomic era, as per http://www.nature.com/articles/srep01330, were there is a reference about Oklo.--Robertiki (talk) 01:50, 22 January 2016 (UTC)

Yes. That is why there is a link to natural nuclear fission reactor in the article. Does the paper contradict that 137Cs has "not occurred on Earth in significant amounts for approximately 1.7 billion years"? No. Kolbasz (talk) 01:53, 22 January 2016 (UTC)
not significant amounts is not zero. Before the atomic era, were there any measurement campaigns about Cs-137 presence in nature ? So how do you know that almost all Cs-137 today is human made ? Have you a source ? Or is it WP:OR ? Negligible seems to me to be more correct than artificial element. --Robertiki (talk) 02:06, 22 January 2016 (UTC)
Because there are no decay paths from any naturally occurring nuclide to 137Cs - the only way 137Cs can be created naturally on Earth is through extremely rare spontaneous fission (as for the inclusion of that, see @Rwflammang's succinct reply above). Which is why it is considered artificial and why it can, as the article discusses, be used to date artifacts. Do you have any sources on naturally occurring Cs-137? (Also, FYI, the "How do you know, were you there?" argument does not reflect well on its user in a science debate) - Kolbasz (talk) 19:07, 23 January 2016 (UTC)
So, the definition of artificial element is that the only way natures creates elements is by radioactive decay ? How do you comment the presence of Cs-137 in uranium mines tailings ? About my sources of naturally occurring Cs-137, before I have to understand what is an artificial element. (FYI, were you there are not my words, and there is another explanation for my strange english, it's not my native language, I merely asked how do we know that almost Cs-137 is human made. I would like to add that Wikipedia, is not the place to do scientific debates) --Robertiki (talk) 04:09, 24 January 2016 (UTC)
An artificial element is a chemical element that does not occur naturally on Earth, and can only be created artificially. --Robertiki (talk) 02:11, 22 January 2016 (UTC)
My proposal is to keep: meaning that until the building of the first artificial nuclear reactor, the Chicago Pile-1, in late 1942, it had not occurred on Earth in significant amounts for approximately 1.7 billion years. and to restore only the other two modifications (negligible and mostly). --Robertiki (talk) 02:14, 22 January 2016 (UTC)
An example for an element: from Technetium: Nearly all technetium is produced synthetically, and only minute amounts are found in nature. Naturally occurring technetium occurs as a spontaneous fission product in uranium ore or by neutron capture in molybdenum ores. That is why I introduced mostly. So, if for technetium we have spontaneous fission in uranium ore, why not for Cs-137 ? --Robertiki (talk) 02:30, 22 January 2016 (UTC)
Adding more: reading http://wwwrcamnl.wr.usgs.gov/isoig/period/cs_iig.html I found: "134Cs has also been used in hydrology as a measure of cesium output by the nuclear power industry. This isotope is used because, while it is less prevalent than either 133Cs or 137Cs, 134Cs can be produced solely by nuclear reactions. 135Cs has also been used in this function." I understand that it is saying that 133Cs or 137Cs are not solely produced by man-made nuclear reactions.--Robertiki (talk) 00:59, 31 January 2016 (UTC)
They're wording it really badly, but what they mean is that 134Cs can be/is produced through neutron capture by stable 133Cs (neutron activation) rather than just as a direct fission product, so it is thus a fingerprint of reactor production rather than weapons fallout. As for comparisons to technetium, there are vast differences in half-lives. Kolbasz (talk) 02:11, 31 January 2016 (UTC)
Your threshold is that technetium is measurable and natural occurring 137Cs is not ? --Robertiki (talk) 02:41, 31 January 2016 (UTC)
@Kolbasz: Not having read any more from you after a week, and having found confirmation of natural abundance in featured article Caesium (in the infobox, under table "Most stable isotopes of caesium") as "trace" I have changed my proposed wording from negligible to trace and mostly with substantially. Here are the resulting changes. I hope it is an acceptable compromise. --Robertiki (talk) 01:21, 31 January 2016 (UTC)
Been busy. Find a reliable source (see note on SCIRP above) on a find of naturally occurring 137Cs and I'll gladly change my mind. Kolbasz (talk) 02:15, 31 January 2016 (UTC)
http://www.ncbi.nlm.nih.gov/pubmed/15824592 from uranium mining activities: " Moose from this area had significantly higher 226Ra, 210Pb, 210Po, and 137Cs in some edible soft tissues vs. one control area.". It is true, that here we have human activity exposing underground elements, but that elements are of natural origin and it looks like that 137Cs levels are measurable. --Robertiki (talk) 02:49, 31 January 2016 (UTC)
More sources:
The New Uranium Mining Boom: Challenge and lessons learned, edited by Broder J. Merkel, Mandy Schipek (Springer) and
http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/44/128/44128588.pdf
--Robertiki (talk) 03:04, 31 January 2016 (UTC)
Sorry, but no. None of the papers refer to a natural origin of the radiocaesium. The moose paper explicitly refers to 137Cs as "a potassium analog and fission product from global fallout and the 1986 Chernobyl accident" and also explicitly contrasts it to "the naturally occurring radionuclide, 40K" (emphasis added). As for the high 137Cs level, the explanation they put forth is that "Lichen ingestion also occurs in moose if forage is poor (LeResche and Davis 1973), which may explain the high 137 Cs levels in meat from one Wollaston moose". The Serbian paper makes no mention of origin at all, but you can safely assume it's from Chernobyl, whose fallout Serbia got its fair share of (you can also note the measurements of 40K, which is primordial and not connected to uranium). The New Uranium Mining Boom is a book I do not have, but from what Google Books lets me search inside it too seems to firmly place 137Cs as anthropogenic.
Before this discussion goes any further, you have to understand the theoretical levels we're talking about here: the rate of spontaneous fission (the only natural process which could generate it) in 238U (which is around 250 times happier to spontaneously fission than 235U) is 5.4×10−7. That is, out of every 2 million decays, only one atom will spontaneously fission. And only a small percentage of those fissions will then yield a 137Cs nucleus. The amounts we're talking about are practically homeopathic. They simply will not show up accidentally as a detectable level in anything, except a specific study to try to find naturally occurring 137Cs in uranium ore. Kolbasz (talk) 20:23, 1 February 2016 (UTC)
"except a specific study to try to find naturally occurring 137Cs in uranium ore" is exactly what I have thought. Uranium is too sparsely distributed on the earth's crust, but where it is concentrated, 137Cs presence should be detectable. --Robertiki (talk) 04:46, 2 February 2016 (UTC)


References

Dose in Finland

At https://en.wikipedia.org/wiki/Caesium-137#3_March_2016_Helsinki.2C_Uusimaa.2C_Finland, it says: "On 3 and 4 March 2016, unusually high levels of caesium-137 were detected in the air in Helsinki, Finland. According to STUK, the country's nuclear regulator, measurements showed 4,000 μBq/m³ — about 1,000 times the usual level". 4,000 μBq/m³, that's 0.004 Bq/m³, a ridiculously small value, which must be wrong... and questions the reliability of the whole article referenced. Does anybody know the real value? Jacques de Selliers (talk) 14:27, 1 June 2017 (UTC)

Banana equivalent

While the edit was undoubtably done in good faith, I reverted this addition by TV4Fun:

By comparison, a typical banana contains approximately 125 Bq/kg of radioactive Potassium-40[1].

While the banana equivalent is good for putting doses in context, an implication-for-health comparison between two different radionuclides using just the activities is like comparing apples and, well, bananas. In this case, the committed effective dose for ingestion of potassium-40 (any compound) is 6.2E-09 Sv/Bq, while for caesium-137 (any compound) it's 1.3E-08 Sv/Bq.[2]

That entire section should be rewritten though - it jumps from topic to topic, sometimes within the same paragraph. Kolbasz (talk) 12:57, 28 June 2012 (UTC)

We could certainly modify the discussion to compare the committed effective dose between eating a banana and eating a serving of food contaminated at the levels mentioned in the article. That would be more accurate and it would help to put the contamination levels in perspective. About the only other comparison this article gives to put dose levels in perspective was a discussion several paragraphs further down about a substantially larger acute dose to a dog, which is not at all relevant to the contamination levels found in the mentioned food items. TV4Fun (talk) 21:14, 28 June 2012 (UTC)

Note that there is only a factor of 2 between potassium-40 (6.2E-09 Sv/Bq) and caesium-137 (1.3E-08 Sv/Bq = 13E-09 Sv/Bq)... Jacques de Selliers (talk) 14:35, 1 June 2017 (UTC)

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Activity

Something seems to be off with the activity. In the article the activivtiy is stated as "One kilogram of caesium-137 has an activity of 3.215 terabecquerel (TBq).[3]"

but from https://en.wikipedia.org/wiki/Chernobyl_disaster#Radioactive_release "20 to 40% of all core caesium-137 was released, 85 PBq in all.[1][129] Caesium was released in aerosol form; caesium-137, along with isotopes of strontium, are the two primary elements preventing the Chernobyl exclusion zone being re-inhabited.[130] 8.5×1016 Bq equals 24 kilograms of caesium-137.[130] Cs-137 has a half-life of 30 years.[1]"

This is a differrence by the factor of 1000! Furthermore Reference [3] does not even state an activity, only a half live 185.110.184.54 (talk) 23:22, 7 August 2017 (UTC)

becquerels per kilogram of caesium-137

For instance "meat from 11 cows shipped to Tokyo from Fukushima Prefecture was found to have 1,530 to 3,200 becquerels per kilogram of Cs-137" ought to be "meat from 11 cows shipped to Tokyo from Fukushima Prefecture was found to have 1,530 to 3,200 becquerels of Cs-137 per kilogram" But of course I would rather see "from Cs-137" than "of Cs-137" DaveyHume (talk) 17:02, 2 September 2017 (UTC)

Cs-137 spectrum

This spectrum is inaccurate. The centroid channel of the 662keV-photopeak is at about 700keV while it should be at .. 662keV.

"10-15% resolution in NaI scintillators" refers to a single photopeak count. Not the photopeak's centroid.


I have 32 spectra with up to 4 different energy photopeaks (500keV-1.2keV), and fitting the centroid VS energy data (constant1*channel+constant2=energy) results in about 0.997 expected-energy to energy ratio.

Idinakis Methodios (talk) 10:43, 10 June 2010 (UTC)


I replaced the image. Idinakis Methodios (talk) 16:09, 9 March 2012 (UTC)


This problem still persists. The center of the peak is above 695 keV, maybe even at 700 keV. (This refers to https://en.wikipedia.org/wiki/Caesium-137#/media/File:Caesium-137_Gamma_Ray_Spectrum-en.svg)

Panphobic (talk) 05:41, 14 July 2017 (UTC)


Agreed, this spectrum is poorly calibrated. Additionally, it might benefit from a removal of the y-axis (the count rate in that particular instance is not relevant in the general case), and a note in the caption to say what kind of detector was used. User3592 (talk) 08:46, 24 October 2018 (UTC)

Timeline Incidents/Accident

It'd better to put Chernobyl and Fukushima Incidents in the time line event there are a lot of information in above sections.--221.133.13.125 (talk) 07:13, 16 May 2019 (UTC)

Incidents and accidents, hints and allegations

This sentence attached to this accident is misleading and should be removed. The reference refers to the general concern of scrap metal being contaminated. It has nothing to do with this specific accident. By placing it here it implies that contamination of scrap metal happened here, which it didn't. Caesium gamma-ray sources that have been encased in metallic housings can be mixed in with scrap metal on its way to smelters, resulting in production of steel contaminated with radioactivity. — Preceding unsigned comment added by Clarksnel (talk • contribs) 16:26, 17 September 2018 (UTC)

An editor recently insisted on calling the accidents described in the article "incidents". In his comment he said, "Incident" and "Accident" have specific meanings in the field. Indeed they do. Perhaps he can enlighten us as to what those meanings are. Rwflammang (talk) 16:09, 15 April 2012 (UTC)

It's the basic severity level principles of general safety engineering/OSH, with accidents being incidents with more severe consequences. In INES, corresponding to an event of level 4 and above. If you want to change the heading to "notable accidents" or suchlike, go ahead - but in that case, the less severe incident in Shaanxi should be removed. Kolbasz (talk) 00:52, 16 April 2012 (UTC)

This apparently still misses the Estonian incident: October 21, 1994 – a large caesium-137 source was stolen by scrap metal scavengers in Tammiku, Männiku, Saku Parish, Estonia.[36] — Preceding unsigned comment added by 2A01:E35:8BE7:3080:157A:EBFE:8B4D:7BDF (talk) 11:59, 6 June 2019 (UTC)

What?

"cesium is not a valid way to spell caesium."

That's patently false. What the heck. — Preceding unsigned comment added by Floam (talk • contribs) 07:35, 8 March 2021 (UTC)

Biological Half-thing

"The biological half-life of caesium isotopes is short (about 100 days for Cs-137)"

I don't think the biological half-life would depend on the isotope, as all isotopes share the same chemical properties. --131.159.36.61

Shouldn't the term be biological half *time*? --Kayvan.walker

Nope, biological half-life is the appropriate terminology utilized within radiation protection field by the US NRC and ICRP — Preceding unsigned comment added by 108.255.57.146 (talk) 01:13, 6 August 2022 (UTC)

  1. ^ Tom Watson (February 26, 2012). "Radioactive Banana! Peeling Away the Mystery". Retrieved June 27, 2012.
  2. ^ Delacroix, D.; Guerre, J. P.; Leblanc, P.; Hickman, C. (2002). Radionuclide and Radiation Protection Handbook. Nuclear Technology Publishing. ISBN 1870965876.
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