I am always interested in the chemistry of cesium, an element in the periodic table that is a cogener - or close chemical analogue - of several better known elements. One such cogener element is lithium - which is famously used in batteries and may even someday power your cool Tesla $100,000 electric sports car, assuming you don't live on the per capita income of say, Mali, in which case the car will cost more than your entire lifetime earnings. Another is sodium. Everyone knows all about sodium. Another is potassium - all of which is naturally radioactive, albeit slightly so - that is a popular nutrient obtained by eating lots of bananas. "Big Mike," the Banana. Less well known are the elements rubidium - which is the most common element in human tissue for which there is no known physiological role - also naturally radioactive, and finally the element cesium, which is found in the form of the mineral pollucite in some of the oldest known rocks on the surface of the earth, the rocks of the Canadian shield.
Natural cesium, unlike natural rubidium and potassium is not radioactive, but the cesium that is formed in nuclear weapons detonations and in nuclear power reactors is very radioactive.
Some years back here, when I was a little less - but not much less - cynical, I estimated the number of people who died each year from tritium, a radioactive isotope of hydrogen, from nuclear weapons tests (and trivial other sources) - assuming that most cancers were fatal, as probably most were then - in 1963. For just tritium my estimate was about 1600 people per year, if people drank two liters of water a day. Profile of Radioactive Substance Associated With Nuclear Power: Tritium. A similar back of the envelope calculation showed that as of 2007, when I wrote the diary - based on observed tritium concentrations, the number of tritium induced cancers - some of which may now be curable - have fallen to something like 13 per year, worldwide, again assuming two liters a day, even accounting for the much larger population than 1963. (If you live in a country where there is no or little palatable drinking water, your risk is lower, from the tritium, since you probably don't get two liters a day.
The reason that tritium related cancers have fallen - in spite of the wide spread development of nuclear power, involving the construction of more than 400 new power reactors after 1963, quadrupling in energy output even since Amory Lovins declared nuclear power "dead" in 1980 - is that tritium has a relatively short half-life, about 12.26 years. Even though nuclear reactors all produce tritium in small amounts - and some of it is released - the reactors contain most of it, and most of it decays before it ever has a chance to get out of the fuel or cooling water.
In the era of open air nuclear weapons testing - after the invention of the hydrogen bomb - tritium was, more or less deliberately, released into the environment as part of the nuclear weapons tests. Interestingly, much of this tritium was made in situ in the core of the nuclear weapons devices during the explosion, from lithium. In this case the lithium was destroyed, or transmuted, into tritium and then immediated fused with one deuterium (a non-radioactive, but heavy, isotope of hydrogen) to make helium and a neutron. The effect of these "successful" nuclear fusion tests - if that's what you wish to call them, "successful" - lead to lots and lots and lots and lots and lots and lots of people to talk endlessly - and thus far uselessly - about the possibility of fusion power reactors. After many years of research - and lots of hype about "promising research" and "breakthroughs" (reminding me of a slightly less useless form of energy that I won't mention) - fusion reactors do not produce significant energy 50 years later, nor is it likely that they will in the current emergency.
The original fusion nuclear weapons test - using a bomb that was as big as a building and contained liquid tritium and deuterium at a temperature on 20 kelvin above absolute zero (-350C roughly) was tested on October 31, 1952. "Big Mike," the nuclear test. It probably consumed more tritium than it made - unlike later bombs - but it certainly released significant amounts of tritium that did not react. However, as I said, the half-life of tritium is only 12.26 years, meaning, by exercise of the radioactive decay law, that less than 4% of it remains, the rest having decayed into helium-3 and escaped earth's gravity. Moreover, of the 4% remaining, it has likely diffused all around the world to be found in all but some very isolated water systems, like ancient fossil water supplies now being mined in Nebraska, Kansas and Texas.
The world's largest nuclear test in history, the Soviet Tsar Bomba test - ironically designated as a "clean" bomb although it was no such thing - briefly (for microseconds) produced a power output equivalent to 1.4% of the sun. In a few minutes it produced as a total energy yield about 0.2 exajoules of energy. This is the equivalent of about 0.2% of all of the energy consumed in the United States as of 2007 (107 exajoules) or about 17.8 hours of energy use throughout the entire United States for all purposes as of 2007. The Soviet designers actually held the thing back - making it smaller than it could have been - since the original design would have increased the world inventory of nuclear weapons fallout by more than 25%, with most of it falling on the former Soviet Union.
Tsar Bomba.
The point of this vast exercise in stupidity was for show - sort of like a Tesla electric car - for as it is stated in the above anti-nuclear weapons link (and I am anti-nuclear weapons) is says:
The nickname Tsar Bomba is a reference to a famous Russian tradition for making gigantic artifacts for show.
Like the Tesla car, the thing was too expensive for real production, not that anyone can object to any weapon - nuclear or otherwise - that is impractical because it is too expensive to manufacture routinely.
If you were born after October 1961, or after October 1952, you have lived with the fallout of several of these exercises in show for your entire life.
Tritium was not the only radioactive isotope released by these explosions by the way. Many other radioisotopes were released, some of which were new elements - the element Einsteinium was first discovered by sifting through the ashes of the "Mike" test conducted by the Americans, which is ironic in a way, since Einstein was a famous pacifist.
Another isotope that was released by the explosion was cesium-137. The first time I ever heard of the element cesium was in connection to radioactive fallout, and my impression as a child was that all cesium was radioactive, but it's not. However cesium-137, which has a half-life of 30.07 years is seriously radioactive inasmuch as it has a half-life short enough to emit a lot of radiation - long lived isotopes release radiation very slowly - inasmuch as cesium is very soluble in water, very volatile and can - more or less - become widely distributed easily in water, air and dust. By direct calculation we can see that about 34% of the cesium-137 released in the Tsar Bomba test, and 28% of the cesium-137 released by the "Mike" test are still present, and, as we shall see, widely distributed on earth.
We can crudely calculate from the data given on Tsar Bomba in the link above, to an order of magnitude, how much cesium-137 was released by Tsar Bomba. We are told that 97% of the explosive yield came from fusion, which we know to be tritium-deuterium fusion. This reaction yields about 17.6 MeV per fusion. The yield of the explosion was 0.22 exajoules and 97% of the energy - we are told - came from fusion and not fission. This suggests that the bomb contained about 380 kg of some mixture of lithium tritide and lithium deuteride - actually a huge amount - with most of the tritium being created in situ from lithium, since 380 kg easily exceeds the world supply of tritium available at any time in history. If the other 3% came from either plutonium or uranium-235/238, it follows that about 80 kg of one or more of these isotopes were consumed in the bomb. The fast fission yield of Cs-137 for fast fission is between 6% and 7%, suggesting - corrected for atomic weight - that the total release of cesium-137 from Tsar Bomba was about 3 kg. The specific activity of cesium-137 is about 87 curies per gram, by calculation, meaning that the "clean" bomb released about 280,000 curies of cesium-137 alone.
By the way, the huge quantity of lithium involved in this explosion suggests that someone ought to consider whether the Tesla electric car - with it's supply of lithium batteries - represents a weapons diversion risk.
Whatever.
Since the cesium formed in the explosion was vaporized by it - again it's a volatile element in any case - it was able to widely distribute around the world, and undoubtedly rained out of the sky in the Northern hemisphere, and to a lesser extent, the Southern hemisphere, for months and maybe even years.
Interestingly, the Tsar Bomba test had the effect of making one of its prime movers - Andrei Sakharov - into one of the most important persons of 20th century - since it transformed him from being a hero of the Soviet Union, awarded this high honor along with the Lenin Prize, for his skill in making stupid bombs for stupid purposes, into a dissident. He was - especially considering the honors and privileges he surrendered to become a dissident - ultimately to prove one of the greatest forces in the second half of the 20th century.
I love the thought of that man, who shows that moral reasoning can and does take place no matter how deep the moral hell in which one begins.
So what of this cesium-137? Like I said, a fair percentage of it is still around and it is still readily detectable all over the earth. No one would have intentionally designed an experiment for the pure purpose of distributing it around the world - but the result was accepted, with some hedging as we see the Soviets reduced the bomb's yield for the purpose of preventing too much of it - for the purpose of making it technically feasible to wire the planet to blow itself up in a matter of hours. The experiment was conducted, and the stuff is still there where it has proved to be experimentally useful, the most useful facet being the tracing of the planet's dying soils.
The following comes from the following reference: Journal of Environmental Radioactivity 99 (2008) 1799–1807. The lead author, L. Mabit, is with the Austrian soil science unit of the IAEA - the International Atomic Energy Agency - winner, as an agency, of the Nobel Prize in Peace.
Quoth Mabit:
Fallout radionuclides (FRNs), and more particularly 137Cs, have been successfully used to quantify erosion and sedimentation processes since 1970s (Walling, 1998, 2002; Zapata, 2002). As demonstrated by the publication of about 4000 research papers dealing with the use of 137Cs, this approach has been shown to provide a very effective means of quantifying erosion and sedimentation rates and to represent a valuable complement to conventional measurement techniques (Ritchie and Ritchie, 2007). The FRNs cesium-137 or caesium-137 (137Cs), excess or unsupported lead-210 (210Pbex) and beryllium-7 (7Be) have been used successfully as tracers of soil redistribution, because they are nonexchangeable, and on delivery to the land surface as fallout they are rapidly and strongly fixed by the surface soil or small sediment particles (Matisoff et al., 2002; Griffitts et al., 1977; Rogowski and Tamura, 1970). Their subsequent redistribution within the landscape occurs primarily through physical processes and they thus provide a very effective tracer of soil and sediment redistribution.
Happy thoughts. They rehash what I said, without the sarcasm:
137Cs is the most widely used of the FRN soil tracers. It has been employed under different agro-environmental conditions in many different areas of the world (e.g. Walling and Quine, 1995; Walling, 1998; Zapata, 2002; Mabit and Fulajtar, 2007). It is an artificial or ‘man-made’ radionuclide (t1/2 30.2 years), generated as a product of the thermonuclear weapons testing that took place from the mid 1950s to the early 1970s, or from nuclear accidents (e.g. Chernobyl). The ‘weapons test’ or ‘bomb-derived’ 137Cs was released into the stratosphere, and distributed globally, before being deposited on the landscape, primarily in association with precipitation. The spatial distribution of the fallout was determined by the location of the weapons testing, the pattern of stratospheric circulation and transport and the annual precipitation amount and shows a clear latitudinal zoning, with total fallout in the northern hemisphere being substantially greater than in the southern hemisphere. 137Cs inventories in the southern hemisphere are, however, still measurable using appropriate detectors and counting times. The fallout of 137Cs released into the troposphere by nuclear accidents, such as the Chernobyl incident, had a more heterogeneous distribution, reflecting the atmospheric circulation and precipitation distribution immediately following the release. This local heterogeneity can introduce problems for interpretation of the spatial variability of 137Cs inventories within a study area where significant Chernobyl fallout occurred. The global pattern of bomb-derived 137Cs fallout indicates that inputs ranged between 160 and 3200 Bq/m^2 depending on latitude (Garcia Agudo, 1998; UNSCEAR, 1969). Fallout 137Cs originating from the Chernobyl accident, which affected many areas in Europe, increased the existing bomb-derived inventories by several orders of magnitude in some locations. In Central Russia, for example, the 137Cs inventories after the Chernobyl accident reached 500 kBq/m^2 (Golosov et al., 1999).
I knew Chernobyl was a problem.
That 500,000 Beq of cesium-137 in central Russia (per square meter) is impressive, by the way, on the order of, more than, ten microcuries.
(Somehow, I don't know how, some guy apparently ended up with a a 10 microcurie source of Cs-137 which he keeps out in the rain, because he's afraid of it.
Scary stuff.)
But what the really scary stuff is what the cesium tells us about our soil. Because the cesium is so easy to detect - it can almost be detected as individual atoms - it is easy to use it to follow what is happening to the soil in which we grow our food and other habitats.
Maybe we really don't want to know about our soil though.
In any case - whether you want to know it or not, one can find a lot of cesium-137 adhering to sediments on the bottom of lakes, reservoirs and oceans. The way that cesium got there was by adhering to soil particles as they washed away, an that is a bigger problem than the cesium itself turned out to be.
