(Immediate Disclaimer: The title could easily be construed as misleading. If you are looking for someone to tell you all about why we should ban nuclear power, I advise you not to read this diary entry - you won't find such an argument made here.)
Ignoring the noble gases, helium, neon and argon, which do not generally participate in chemical reactions, of the first 30 elements in the periodic table only a few have almost no role in biology. Those elements are lithium, beryllium, boron, aluminum, fluorine, scandium, and titanium.
By contrast, only two of the next 80 or so elements are known to play key roles in living systems, molybdenum and iodine.
There are some reasons, I think, for this, mostly having to do with cosmic abundance, and to a lesser extent, chemistry.
Most moderately well educated people are aware that the origin of all of the elements except for those created in the "big bang" involves formation in a star from nuclear reactions. (Hydrogen represented the vast bulk of the elements formed in the "big bang," but a little helium and lithium is believed to have formed as well in this primordial event.)
Elements heavier than lithium, including the carbon which makes up a significant fraction of you were mostly ejected by stellar explosions from stars that exhausted their fuel, collapsed and then, in a kind of rebound, blew up as supernovae. These explosions distributed heavy elements, up to and including uranium, throughout the universe.
It happens though, that this process does not account for the existence of three light elements. Neither lithium, nor beryllium, nor boron are stable elements in stars. All three elements are consumed in stars, and rather rapidly at that. If lithium, either from the big bang or from elsewhere, falls into a star, it is rapidly destroyed, not formed.
Still all of these elements exist here on earth. Lithium is found in batteries that many people use all the time. Beryllium is somewhat more esoteric, but it is widely known. Boron is common enough, it's been used as a laundry detergent, one that was hawked by Ronald Reagan as "20 Mule Team Borax" in his "movie star" days. Even so, out in space, in terms of "cosmological" abundance, these three elements are relatively rare and indeed they are not common elements even on this planet. It is my guess that when life first formed on this planet, there wasn't much of these elements around to play with, so life developed its chemistry without them. (Although fluorine and aluminum are both relatively common elements on earth, they form lots of insoluble immobile compounds, and so life did without them too).
As it happens, it is believed that all of the lithium, beryllium and boron that exist were formed not in stars but in cold interstellar clouds when very energetic particles - cosmic rays - ran into heavier elements causing little pieces - the light elements themselves - to be "chinked off." This process, which is rare and esoteric, is called "spallation." The universe is so vast that spallation can make appreciable quantities of these elements. Still, on earth as well in space, they are relatively rare. Life avoided their use.
The nuclear properties of the elements - nuclear synthesis of the elements in stars - manifests itself in the chemistry of life in other ways as well. If one plots the "binding energy" of the elements - the glue that sticks the bundles of protons and neutrons that make up their nuclei - against atomic number, one finds that iron is the most stable element there is. If one is making iron from lighter elements, one can take energy out. If on the other hand, one is trying to make elements that are heavier than iron, one must put energy in. In normal stars there is something of a tendency to overshoot this limit, but once one gets much past zinc, an element that plays a fairly important role in living systems, the cosmic abundance of the heavy elements is somewhat limited and so the biochemistry of these elements is limited. Only a few elements are more common than iron, and all are light.
This interesting fact accounts almost certainly for the fact that there are no proteins or other molecules that are important to life that depend on the chemistry of rhodium, even though rhodium is a very cool element that can catalyze lots of very interesting chemical reactions. Rhodium is just too rare to be essential.
All of the above makes it very difficult to account for the fact that iodine, element 53, far removed from iron (element 26), is essential to life, but it is. Iodine is a big exception to this rule. Iodine is far less abundant in earth's crust than either uranium or thorium, but thorium and uranium, though found in living tissue, have no known physiological role in any living organism. On the other hand, many types of organisms depend on access to iodine to live, from humans to insects to various kinds of plants. Some plants, like ocean kelp, greedily scoop up all of the iodine they can, and they expend considerable energy doing so. The proteins and the genes for concentrating and storing iodine from very dilute sources of the element are widely distributed and the genes responsible for them are thought, in evolutionary terms, to be very old, hundreds of millions of years old, maybe even billions of years old. Iodine is a diffuse element. It is widely distributed. It gets around the planet pretty easily and it is somewhat problematic to get it to stay in one place.
It is almost always true that DKos diary entries written by NNadir are about energy, most often about nuclear energy, and this one is too. The reason is that iodine, for all of its other interesting properties, is a very common fission product. When, in a nuclear reactor, an atom of uranium or plutonium or other actinide element is split, releasing energy, it is very common for iodine to be formed. Sometimes the iodine that is formed is the isotope that is the only stable non-radioactive isotope of iodine, I-127, but more often the iodine that is formed is radioactive. In fact, when one looks at the majority of long term complications of the manufacture, use and testing of nuclear weapons, as well as the effects of the famous nuclear accident at Chernobyl, a huge fraction of the injuries involve the fact that iodine is a fission product.
For instance, if one fissions an atom of uranium-235 with a "thermal" neutron, an atom of the extremely radioactive isotope I-131 will result about 2.88% of the time. If one fissions plutonium-239 with a "thermal" neutron, one will get an atom of I-131 about 3.84% of the time.
Happily, the half-life of I-131 is relatively short, about 8.02 days. This means that while I-131 is present when a nuclear reactor is operating, eventually it will reach an equilibrium concentration in the reactor where it is decaying about as fast as it is being formed. Once the reactor is shut down, all of the I-131 will rapidly decay, disappearing more or less completely within a few months. However if something happens - as happened at Chernobyl and as happened every time a nuclear weapon was detonated in the atmosphere (and even when nuclear weapons were detonated underground) - to release this iodine to the environment before it decays, then living things will pick it up and concentrate it at certain places in their flesh. It can be shown that a large fraction of the deaths connected to nuclear technology, both military and civilian, are related to I-131. In fact, in one of the ironies of the whole situation, it will be concentrated in such a way as to find itself about as close to DNA molecules as you can get.
Now that's unhappy news.
As was the case when I recently discussed another product made in nuclear reactors, where I showed that people were exposed to tritium contamination mostly by nuclear testing. Many people who were then children were exposed to radioisotopes as the result of this very questionable arms race. I was one of them. Probably I had measurable quantities of I-131 - not that anyone checked - in my thyroid because of the Soviet-American-English-French arms race. More than 40 years have passed since I ingested my last glass of milk containing I-131 released by an American or Soviet open air nuclear weapons test, but the die is cast. I was eleven years old, and there is not a damn thing I could have done about it. I may still get thyroid cancer or some other cancer from it yet, you never know.
Thankfully, all of the iodine-131 released in 1963 has decayed. I doubt that even one atom of iodine-131 formed back then exists on the planet. All of the iodine-131 is now atoms non-radioactive gas Xenon-131, and it is almost certain at some point during the day you will breathe one of these atoms at least one or two of these atoms. (If one wishes to see an interesting calculation of this type, see problem 2.30 of Gilbert Castellan's Physical Chemistry, 3rd Edition Addison Wesley, wherein one is lead to calculate how many breaths one must take in order, on average to breath in an Argon atom from Ceasar's last breath: The answer is 53.)
Let me tell you something else. Irrespective of the fate of the iodine-131 from the nuclear testing era I am in no ways done with eating radioactive iodine, even though nuclear weapons testing has happily been cut back around the world.
Of the iodine atoms produced by human induced nuclear fission, only one is not radioactive, iodine-127, (0.12%) the only stable isotope of iodine. Other iodine isotopes, besides I-131, that are formed in appreciable amounts in nuclear fission reactions include I-129 (0.7%), I-132 (4.2%), I-133 (6.0%), I-134 (7.7%), I-135 (6.3%), I-136 (2.5%), and I-137 (3.2%). The numbers in parentheses refer to the percentage of fissions of U-235 induced by thermal neutrons that result in the formation of one of these isotopes. Except for I-129, all of these isotopes have half-lives of less than a few hours. Equilibrium is quickly established in operating nuclear reactors and when the reactors are shut down and the fuel removed, almost all of the iodine rapidly decays to isotopes of xenon or cesium, most of which are not radioactive at all.
The only exception is I-129.
I-129 has a half life of 15,700,000 years. Almost all of the iodine-129 released in the international pissing match between Nikita Khrushchev and John Kennedy (and before him Dwight Eisenhower) is still out and about and it is still radioactive. Unquestionably, you have radioactive iodine in your body right now that comes from this source. Nuclear weapons testing materials is in your flesh right now and there is nothing, absolutely nothing, you can do about it.
How much radioactive iodine-129?
Before I answer that question, let's turn for a minute to the title of this diary entry. I have deliberately chosen the title of this entry to be phrased in the inflammatory way that almost all nuclear news is reported by the media. That said, the title is accurate. There is radioactive iodine in the Mississippi River, and it can be shown that the source of this radioiodine is French nuclear reactors. The reason it is there because the French - who are the most advanced nuclear power nation on earth - do what I think every nation should do: They reprocess their spent nuclear fuel.
Either before or after suggesting that I am either a paid nuclear lobbyist or Patrick Moore's Sockpuppet, a subject I have discussed in my diary already several times, people will start to talk about how "radiation causes cancer," and a whole bunch of other things. Of course, in making these assertions they will ignore the reality that particulate matter released from burning fossil fuels also causes cancer. In short they will insist, as always, that nuclear energy must be risk free, and pretend that everything else is already risk free. This state of affairs repeats itself in all of my repetitive diary entries.
Why repeat it then? Because it's important, that's why.
Implicit in a lot of thinking these days is the assumption that if industry spokesmen say one thing or another - and I would love to be paid as a nuclear industry spokesman by the way and would be proud of doing so - they are lying. This is, however, nonsense. Some industries do tell lies about their products, minizing their risks. The cigarette industry famously claimed that cigarettes do not cause cancer, but cigarettes do cause cancer. Exxon-Mobil spends a lot of money trying to prop up desperate scientific arguments about fossil fuel induced climate change, but climate change is real and it is caused by the burning of fossil fuels. All of that said, I spend a fair amount of time over at nuclear industry funded websites. I agree with almost everything that is written on them. They are saying the right things and telling, in fact, truths that many people find inconvenient.
Climate change is a very serious matter and our options are limited.
So what about that French reactor waste in the Mississippi River? The matter is discussed in the scientific literature. A discussion of French I-129 in the Mississippi River is the topic of a paper written by scientists at Texas A&M, Purdue and Lawrence Livermore National Laboratory. The reference is Santschi et al, Environ. Sci. Technol. 2001, 35, 4470-4476. Here is an excerpt that pretty much reproduces everything I have said in this entry and then some:
Iodine is a biophilic element, occurring in the environment primarily as 127I (natural abundance nearly 100%) with several radioisotopes of which the only long-lived isotope is 129I (half life) 5.6 X 10^6 years). 129I is produced by cosmic ray-induced spallation of Xe in the atmosphere, by spontaneous fission of 238U in the earth’s crust, and by human activities, such as nuclear bomb testing and nuclear fuel reprocessing (1). The amount of natural 129I in the surface environment is approximately 100 kg (2-4), while atmospheric bomb testing has contributed an additional 150 kg, equivalent to about 27.3 Ci (5), and the Chernobyl reactor accident 1.3 kg (6). The dominant sources of 129I in recent years are fuel reprocessing plants located at Cap de La Hague, France, and Sellafield (formerly Windscale), England. These plants have contributed about 2360 kg or 420 Ci of 129I between 1966 and 1997 (4). Their atmospheric releases have increased in the past decade, providing the largest point source for 129I in the surface environment. These releases have completely overwhelmed the natural background ratios of 129I/127I.
The bold is mine.
Those sound like some very dangerous plants, no?
Let's read further:
Even relatively small amounts of atmospherically delivered 129I transported from the Sellafield/La Hague region can drastically change 129I/127I ratios in surface waters, soils, and biota in the U.S. 8, 9). Elevated 129I/127I ratios in surface environments of the U.S. have recently been reported (8-14). Moran et al. (8, 9) found higher 129I/127I ratios in meteoric water and epiphytes in the continental U.S. as compared to coastal seawater, indicating that atmospheric transport is an important distributor for surface 129I.
If I were a paid lobbyist for the middle and upper class "environmental" circus stunt performing group Greenpeace - something I would never agree to do on ethical grounds - I could sure get some mileage out of these remarks, couldn't I?
Now there's a lot of other remarks in this scientific report that I could take out of context and spin to make this all seem absolutely horrible. But let's cut to the chase. What exactly is the ratio of I-129/I-127?
Well it turns out that the ratios fluctuate with the flow rate. Here is the results:
During base flow, 129I and 127I are being similarly concentrated by ET, with only small amounts of 127I removed to soils, as 129I/127I ratios are close to the average ratio in rainwater (3.8 +/1 X 10^-9) calculated from individual ratios, 2.4 +/1 0.65 X 10^-9 from individual average concentrations of 129I and 127I (8)). During times of higher flow rates (i.e., spring time), extra inputs of 127I from soil weathering reactions and sediment resuspension cause a decrease in the 129I/127I ratio.
(I have edited this text to render the scientific notation into a form that makes sense in the DKos editor.)
In other words, between one in every 200 million and one in every 500 million atoms of iodine found in the Mississippi river is radioactive I-129, probably derived from a French (or English) nuclear fuel reprocessing plant.
What does this mean?
The rest of the calculations found here are mine. Anyone who feels competent to challenge them is invited to do so.
According to the periodic table I referenced above, even though iodine is an essential element, one doesn't require a great deal of it. The human body is about 200 parts per billion iodine by weight. This means that a 70 kg human being contains about 14 milligrams of iodine. According to the paper referenced, if a person obtained all of their iodine by drinking water from the Mississippi River, on the worst day with the highest concentration of I-129 relative to non-radioactive I-127, one in every two hundred million atoms of iodine would be radioactive I-129 from the French or English nuclear reprocessing plants.
This means that the average 70 kg person contains (at worst) 72 trillionths of a gram of radioactive I-129.
The specific activity of I-129 is 6.52 million decays per gram. This means that a 70 kg person would need to wait 35 minutes to have even a single nuclear decay from iodine. For comparison purposes every 70 kg person on the planet experiences more than 4000 such decays each second from natural potassium. Moreover, the radioactive potassium-40 found in all water on earth, releases far more energy per atom than does an atom of I-129.
I am about to hear all sorts of happy horseshit about renewable energy, but I don't buy any of it. The real risk of nuclear energy is that it won't be used in the immediate climate change crisis because people despise rationality. Nevertheless the climate change crisis remains extremely urgent. People want to believe all sorts of appeals to irrational nonsense, including the nonsense that there is such a thing as risk free energy and renewable energy is an example of it. But even if renewable energy were risk free, and it's not, there is not enough of it to make even a dent in the crisis. There is no such thing as risk free energy, not renewable, not nuclear. There is only risk minimized energy. That energy is nuclear energy.
One might ask why those nasty French don't stop releasing radioiodine or whether they could do so if they wished. The answer probably is that they could probably capture all of their iodine, but to do so might be expensive. "Pay any expense!" you say, "It's radioactive!
Bullshit. I contend that if the number of people who have died from French radioiodine is not zero, it is very, very, very, very close to zero. Suppose that to prevent the release of radioiodine we required those nasty French to spend 100 million dollars to capture and contain all of their iodine. How many lives would be saved? One, maybe two, if that. Now ask yourself how many lives could be saved by donating 100 million dollars to an AIDs prevention program in Zimbabwe. I am morally averse to putting a 100 million dollar price tag on one life just because that life might be injured by a nuclear related event.