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Thursday, 14 November 2013

What's in Alaska fish these days, you ask? Cesium-137, Americium-241


D'un Renard: Fellow reporter Rainbow Warriors

[snip]

* Cesium-137 — 3.854 pCi/kg in Dolly Varden fish
* Cesium-137 — 5.312 pCi/kg in goose Egg no shell
* Cesium-137 — 5.199 pCi/kg Gull egg
* Cesium-137 — 8.094 pCi/kg Chiton
* Cesium-137 — 4.981 pCi/kg Dragon Kelp
* Cesium-137 — 2.365 pCi/kg Rockweed
* Cesium-137 — 13.254 pCi/kg Greenling
* Cesium-137 — .384 pCi/kg Halibut
* Cesium-137 — 125.381 pCi/kg Horse Mussel soft tissue
* Cesium-137 — 15.505 pCi/kg Irish Lord
* Cesium-137 — 1.425 pCi/kg Octopus
* Cesium-137 — .995 pCi/kg Pacific Cod
* Cesium-137 — 10.216 pCi/kg Rockfish
* Cesium-137 — 16.749 pCi/kg Sea Urchin
* Cesium-137 — 25.254 pCi/kg Reindeer Lichen

* Americium-241 — .008 pCi/kg Dolly Varden
* Americium-241 — .106 pCi/kg Goose Egg no shell
* Americium-241 — .05 pCi/kg Chiton
* Americium-241 — .024 pCi/kg Dragon Kelp
* Americium-241 — .024 pCi/kg Rockweed
* Americium-241 — .098 pCi/kg Greeling
* Americium-241 — .008 pCi/kg Halibut
* Americium-241 — 1.678 pCi/kg Horse Mussel tissue
* Americium-241 — .11 pCi/kg Irish Lord
* Americium-241 — .003 pCi/kg Octopus
* Americium-241 — .01 pCi/kg Pacific Cod
* Americium-241 — .085 pCi/kg Rockfish
* Americium-241 — .091 pCi/kg Reindeer Lichen
* Americium-241 — .02 pCi/kg Sea Urchin

[end snip]

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[wiki]

Americium is a transuranic radioactive chemical element that has the symbol Am and atomic number 95. This transuranic element of the actinide series is located in the periodic table below the lanthanide element europium, and thus by analogy was named after another continent, America.[2]
Americium was first produced in 1944 by the group of Glenn T. Seaborg at the University of California, Berkeley. Although it is the third element in the transuranic series, it was discovered fourth, after the heavier curium. The discovery was kept secret and only released to the public in November 1945. Most americium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 100 grams of americium. It is widely used in commercial ionization chamber smoke detectors, as well as in neutron sources and industrial gauges. Several unusual applications, such as a nuclear battery or fuel for space ships with nuclear propulsion, have been proposed for the isotope 242mAm, but they are as yet hindered by the scarcity and high price of this nuclear isomer....
...he discovery of americium and curium in 1944 was closely related to the Manhattan Project; the results were confidential and declassified only in 1945. Seaborg leaked the synthesis of the elements 95 and 96 on the U.S. radio show for children, the Quiz Kids, five days before the official presentation at an American Chemical Society meeting on 11 November 1945, when one of the listeners asked whether any new transuranium element beside plutonium and neptunium had been discovered during the war.[8] After the discovery of americium isotopes 241Am and 242Am, their production and compounds were patented listing only Seaborg as the inventor.[13] The initial americium samples weighed a few micrograms; they were barely visible and were identified by their radioactivity. The first substantial amounts of metallic americium weighing 40–200 micrograms were not prepared until 1951 by reduction of americium(III) fluoride with barium metal in high vacuum at 1100 °C.[14]...
...The longest-lived and most common isotopes of americium, 241Am and 243Am, have half-lives of 432.2 and 7,370 years, respectively. Therefore, all primordial americium (americium that was present on Earth during its formation) should have decayed by now....
Existing americium is concentrated in the areas used for the atmospheric nuclear weapons tests conducted between 1945 and 1980, as well as at the sites of nuclear incidents, such as the Chernobyl disaster. For example, the analysis of the debris at the testing site of the first U.S. hydrogen bombIvy Mike, (1 November 1952, Enewetak Atoll), revealed high concentrations of various actinides including americium; due to military secrecy, this result was published only in 1956.[15] Trinitite, the glassy residue left on the desert floor near AlamogordoNew Mexico, after the plutonium-based Trinity nuclear bomb test on 16 July 1945, contains traces of americium-241. Elevated levels of americium were also detected at the crash site of a US B-52 bomber, which carried four hydrogen bombs, in 1968 in Greenland.[16]
In other regions, the average radioactivity of surface soil due to residual americium is only about 0.01 picocuries/g (0.37 mBq/g). Atmospheric americium compounds are poorly soluble in common solvents and mostly adhere to soil particles. Soil analysis revealed about 1,900 higher concentration of americium inside sandy soil particles than in the water present in the soil pores; an even higher ratio was measured in loam soils.[17]
Americium is produced mostly artificially in small quantities, for research purposes. A tonne of spent nuclear fuel contains about 100 grams of various americium isotopes, mostly 241Am and 243Am.[18] Their prolonged radioactivity is undesirable for the disposal, and therefore americium, together with other long-lived actinides, have to be neutralized. The associated procedure may involve several steps, where americium is first separated and then converted by neutron bombardment in special reactors to short-lived nuclides. This procedure is well known as nuclear transmutation, but it is still being developed for americium.[19][20]...

Health issues[edit]

As a highly radioactive element, americium and its compounds must be handled only in an appropriate laboratory under special arrangements. Although most americium isotopes predominantly emit alpha particles which can be blocked by thin layers of common materials, many of the daughter products emit gamma-rays and neutrons which have a long penetration depth.[104]
If consumed, americium is excreted within a few days and only 0.05% is absorbed in the blood. From there, roughly 45% of it goes to the liver and 45% to the bones, and the remaining 10% is excreted. The uptake to the liver depends on the individual and increases with age. In the bones, americium is first deposited over cortical and trabecular surfaces and slowly redistributes over the bone with time. The biological half-life of 241Am is 50 years in the bones and 20 years in the liver, whereas in the gonads (testicles and ovaries) it remains permanently; in all these organs, americium promotes formation of cancer cells as a result of its radioactivity.[17][105][106]
Americium often enters landfills from discarded smoke detectors. The rules associated with the disposal of smoke detectors are relaxed in most jurisdictions. In the U.S., the "Radioactive Boy Scout" David Hahn was able to concentrate americium from smoke detectors after managing to buy a hundred of them at remainder prices and also stealing a few.[107][108][109][110] There have been cases of humans being contaminated with americium, the worst case being that of Harold McCluskey, who at the age of 64 was exposed to 500 times the occupational standard for americium-241 as a result of an explosion in his lab. McCluskey died at the age of 75, not as a result of exposure, but of a heart disease which he had before the accident.[111][112]
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