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It appears that this will represent, should I publish it, the 373rd diary I've written here.

Um...um...jeeze...this after taking a break for a year or so...jeeze...

My first diary was in the last quarter of 2006, meaning that I've been at this for 5 and a half years, roughly, and the themes I've been at are pretty much constant, although I will confess that some of the research I've done in preparing my diaries has caused me to change my ideas about some things, but more or less the themes are constant.

Other things have remained more or less constant as well.   No real progress has been made at slowing the rate of dangerous fossil fuel waste dumping into Earth's atmosphere - 5 years ago is roughly 150 billion tons of dumped dangerous fossil fuel waste - represented as carbon dioxide - ago, and roughly more than 10 million deaths from air pollution ago.

Time.   Time moves on, no matter how you choose to measure it.

My fifth diary here was on the subject of the Oklo Natural Nuclear Reactors and recently - after hearing the same sort of constant things I hear about how the nuclear weapons waste in the Hanford tanks, near Richland, Washington, is going to kill everyone in Washington and Oregon, much as the Fukushima tsunami wiped out everyone in Japan because it hit nuclear reactors, and much as Chernobyl wiped out Kiev, Ukraine and much as Three Mile Island wiped out Harrisburg, PA - I was reminded about my long ago diary on Oklo.  

My fifth diary got three comments, and three recommends.  I should have quit while I was ahead.

The Oklo natural nuclear reactors operated almost 2 billion years ago, in an area of Africa that is now modern day Gabon, and physicists have been interested in them as they help calibrate the values of "fundamental constants" which may not, in fact, be "constant."    More below...

The start up of the Oklo reactors in a sandstone matrix almost certainly took place when oxygen - which was then a poison, since it wiped out 90% of the species on this planet, all of which were unicellular - appeared in the planetary atmosphere.

Most everybody knows - with the possible exception of members of Greenpeace since the overwhelming majority of them are blissfully unaware of the contents of science books - that natural uranium contains three isotopes, U-238, U-235, and U-234.   Respectively these three isotopes have half lives of 4.468 billion years, 703.8 million years and 245,500 years.   Since the earth is about 4.5 billion years old, the latter could not have survived from the primordial supernovae that account for all of the heavy elements found one earth, however it is in radioequilibrium with its parent nuclide, U-238, about half of which has survived since the formation of the earth.   U-234 is formed by the following nuclear decay reactions:

 U238 -> Th234 + He4

Th234 -> Pa234 + e-

Pa234 -> U234 + e-

The helium nucleus and the electrons in the above nuclear reactions - which have always taken place on earth - are travelling at very high speeds during these reactions and are respectively called alpha particles and beta particles, as everyone knows (unless, again, one is qualified to join Greenpeace).  U234 is radioactive, much more radioactive than either of the other two uranium nuclei that naturally occur, but it is also at radioequilibrium, which is the condition obtained when a the radioactive isotope is decaying at almost precisely at the same rate as it is being formed.   The isotope with the shortest half life is the one that is present in the smallest quantity, and despite the fact that U234 is highly radioactive when compared with  U238, this is why the radioactivity of purified isolated uranium is trivial.   If the parent nucleus is also radioactive (as is almost always the case) the ratio of the concentration of of the two isotopes present after equilibrium has been obtained is a function of their two half-lives.    

The mathematics of this situation is relatively straightforward and a good description of it can be found at the website of the Nobel Prize winning organization - an anti-ignorance organization - the International Atomic Energy Agency, the IAEA.

Here's the link to the IAEA page on the laws of radioactive decay: Laws of Radioactive Decay.

As one can see therein, the relative concentration of two radioisotopes is given by the ratio of their decay constants, λ1 and λ2, wherein the value of λi is equal to the natural logarithm of 2 divided by t1/2i, where  t1/2i is the half-life of the ith radioactive isotope.    That is:

λi = ln(2)/ t1/2i
The decay constant for U238 is 1.55 X 10-10 years-1 and for U234 is 2.82 X 10-6  years-1 and the ratio of these two constants is roughly 18,200.   Thus for every atom of U234 in a sample of U238 at equilibrium, 18,200 atoms of the latter are present.   Put another way, 0.0055% of uranium is the U234.   This calculated result conforms almost exactly with the observed distribution of uranium isotopes in solid uranium ores.   (The ocean is a dilute uranium ore, containing approximately 5 billion tons of uranium that has weathered out of rocks, however the ocean under certain conditions can be disturbed from reaching radioequilibrium owing to the low solubility of Th234, an intermediate short lived isotope between uranium isotopes, but the effect is extremely minor.)

So called "depleted uranium" is not at equilibrium.   In the link above one can see that the time required to reach equilibrium between two radioactive isotopes is given by the relation:

tmax = (1/(λ21)) ln(λ2 / λ1)
 

For the U238,  U234 couple, the period of time required for the isotopes to come to equilibrium is about 3.47 million years.   This is much shorter than the age of the earth (unless of course you're Rick Santorum and think that the "biblical" age of the earth is incontrovertible) and thus all natural solid uranium is at equilibrium, but depleted uranium, which does not occur naturally (in most cases, excluding as we shall see, Oklo ores) cannot be more than 70 years old, is not.

So called "depleted" uranium is the least radioactive of all known types of uranium, since the same process that removes U235 from natural uranium also removes U234, at least in the case where gaseous diffusion - the most common process for uranium isotope separations - is used.   (The much more modern but less widely employed laser excitation methods do not remove U234 quite as efficiently from natural uranium.)

Primordial U235 has survived since the accretion of the earth, since its half-life is long enough.   If we take the age of the earth to be 4.5 billion years, roughly close to the half life of  U238, we can directly calculate that about 1.2% of the original U235 that was here when the earth formed is still here.   Suppose we have a kilogram of natural uranium.   This uranium would contain about 7 grams of U235, and 993 grams U238 along with trivial amounts of U234.    The mass of uranium that is present survives from a larger mass that was present when the earth formed, roughly 1986 grams of original U238 and 589 grams of U235.   Thus the concentration of the latter isotope would have been about 23% U-235 in the total uranium and the uranium would be far more enriched than the uranium in commercial nuclear reactors like those that have operated for 55 years or so.  (Commercial reactors typically have enrichments between 2 and 5 percent.)

Uranium of this type could easily go critical under certain conditions, specifically in the presence of a moderator.   About 2 billion years ago, all of the uranium found on earth was about 3.7% U-235, which is sufficiently concentrated to go critical in the presence of a water which is the main moderator used in commercial nuclear power plants.   This is precisely what happened at Oklo.

As geologists know, many ores on earth are reduced ores.   For instance the mineral sphalerite is zinc sulfide, ZnS.   Pyrite is an ore of iron, and its formula is FeS2, whereas mercury sulfide is the mineral cinnabar which has the formula HgS, and lead's ore is galena, PbS.    The metals can be obtained from these ores by roasting them in air, during which the sulfur atoms (or in the case of pyrite, disulfide) are oxidized to sulfur oxides, which accounts for much of the air pollution involved with smelting operations.   The formation of these ores takes place in reducing conditions in the absense of oxygen.   Planets with atmospheric oxygen seem to be exceedingly rare in the universe, and earth was no exception to this general rule more than two billion years ago.   However when photosynthesis evolved, the chemistry of the earth changed dramatically, owing to the growth in atmospheric oxygen, so that new ores that formed after the oxygen concentrations grew were often oxides.

In some cases, though obviously not all, ores of metals were converted from largely insoluble and immobile sulfides into oxygen species.

I mentioned that the earth's oceans contain billion ton quantities of uranium, which is actually only a fraction of the uranium that is present on the planet.   (This uranium, along with radioactive thorium and radioactive potassium accounts for almost all of the internal heat of the earth.)  Uranium oxides and oxo cations are slightly soluble in water, and thus can solvate.   Moreover uranium has many well defined oxidation states and the mobilization of uranium is understood, even today - where it is widely studies because of the concern that uranium be "safe" for all eternity and injure no one, whereas no one can be safe, even for 15 seconds, from the effects of dangerous fossil fuel waste, a.k.a "air pollution - we understand that oxygen is responsible for the mobilization of uranium in either natural or synthetic (often unintended) uranium ores.  Thus, happily, we understand the geochemistry of uranium extremely well.  At Oklo, relatively diffuse concentrations of uranium oxides, which formed after other uranium species were exposed to oxygen either solvated in water or in the atmosphere, leached through porous sandstone where for chemical reasons they reprecipitated forming a common uranium ore known as pitchblende, which is largely UO2 with some more oxidized material, UO3 being present.   The process went on for many millions of years, in the presence of water, which acted as a neutron moderator.   Eventually the concentrations in these ores became so high that an appreciable flux of neutrons became present from spontaneous fission of uranium isotopes and their decay products and from the interaction of alpha particles with light elements to produce even more neutrons.   Some of these neutrons caused nuclear fission.   Probably for millions of years these fission events were what we now call "subcritical."  Although stray neutrons from spontaneous fission in natural uranium - which, again, two billion years ago was "enriched" uranium - caused fission in other uranium atoms, more neutrons leaked out of the system or were absorbed in non-fissionable nuclei, than caused fissions.   Eventually, as the deposits grew larger, the probability of neutrons leaking out of the ore bodies without striking a U235 atom became sufficiently small that a chain reaction started, in other words, the uranium ores went critical and a natural nuclear reactor started.

At Oklo, there were about 16 of these "reactor zones" or "RZ" as scientific papers sometimes call them.

They operated for about half a million years in a cyclic fashion, the cycles taking place because of a negative void coefficient, a feature of the vast majority of commercial reactors that now provide electricity to humanity.   The power output of the reactors was small, roughly 100 kW(th).   From the ratio of isotopes of the element lutetium - which is not appreciably a fission product, but which is nonetheless present in the reactor zones - scientists deduce that the operating temperature of the reactors was about 280oC +/- 50oC.  This analysis is possible because the neutron capture cross section of the two natural isotopes of lutetium vary quite dramatically with temperature.  (c.f. L.V. Krishnan "Oklo Natural Fission Reactor" Nuclear Energy Encyclopedia: Science, Technology, and Applications, First Edition (Wiley Series On Energy). Edited by Steven B. Krivit, Jay H. Lehr, and Thomas B. Kingery.© 2011 John Wiley & Sons, Inc. pp. 51-55.)  These reactors were thermal reactors, meaning that they required a moderator, a substance with low atomic mass, to slow the neutrons down to speeds that are typical of molecules at what we now call "room temperature."   As the reactors went critical, the water in them boiled and may have even vented as steam.   The loss of this water deprived the reactors of a moderator, and thus the nuclear reaction stopped, only to restart when the reactors cooled and cool water diffused into them as groundwater.

The reactors operated, again, for half a million years, roughly on aveage, and their formation depended on a flux of water moving through them.   What is interesting is to learn what happened to the fission products, most of which were radioactive in the beginning, that resulted from these reactors.   The answer has been extensively analyzed in great detail, and the answer to the question is "not much."   Over two billion years, most of the fission products in porous sandstone at Oklo didn't even migrate as far as Tom Brady can throw an errant football in a "Hail Mary" pass at the end of a Superbowl as a last ditch attempt to avoid a losing effort.  

In two billion years.  

Speaking of losing efforts, and losers, in order to prove that nuclear energy is as unsafe as dangerous fossil fuels, anti-nukes would need to establish that nuclear energy kills two million people per year, which is what air pollution, not counting climate change, kills every year.    Despite much hopeful rhetoric on their part hoping that such a number of people would die from the destruction of three nuclear reactor cores at Fukushima after an earthquake and inundating tsunami, and lots of cheering for a hoped for disaster of this sort, even the destroyed reactors have not caused the death of anyone, never mind the two million people that die each year, every year, from the normal operations in which oil, gas, coal and biomass are burned in our threatened oxygen containing atmosphere.   Thus far, despite much hoopla and wishful thinking, the Fukushima reactors in an earthquake and tsunami have not proved as dangerous as dams in an earthquake and tsunami, or buildings in an earthquake and tsunami, or cars in an earthquake and tsunami.

At Greenpeace they may be muttering "Wait 'til next year!" just like Tom Brady might be muttering the same thing for different reasons.

Anyway, to return to the point:  The Oklo reactors were continuously inunated with water; their existance depended on the presence of water and oxygen, flowing water.   There is no evidence that the unicellular life at that time made any effort to place the fission products in stabilized vitrified glass and steel containers, and of course, it seems that at no time in it's geological history over the past two billion years was Gabon a desert.   It certainly isn't one now, although humanity is working on it.

So much for the theory that if Yucca Mountain had opened - and to be clear I opposed Yucca on the grounds that all of the constituents of used nuclear fuel are far too valuable to be dumped - that everyone in Nevada, Southern California, and Western Arizona would have died from radioactivity.   I would guess that even if Nevada became a rain forest, that it would take millions of years for as many people to die from leached radioisotopes as will die in the next ten minutes from dumped dangerous fossil fuel waste from the normal operations of dangerous fossil fuel power plants and dangerous fossil fueled devices.   That is I doubt that if opened, Yucca mountain would have been as dangerous as lawn mowers in New Jersey.   As it happens, I live in New Jersey, and I assure you I am continuously breathing lawn mower dirt - especially the particulates that lawnmowers produce in the form of dangerous fossil fuel waste - in summers.   Thus I am not "safe."  The probability that I am immortal and will live forever is, um, zero.   Lawn mower waste or even more likely something else, like say, my dietary habits, will kill me.

The fossil reactor cores at Oklo are somewhat depleted in the fission gas isotopes of xenon and krypton - the latter which would have in the case of the 85 isotope have long ago decayed into rubidium-85, Rb85 making it the only non-radioactive rubidium on earth. (The other naturally occurring isotope of rubidium, Rb87, is naturally radioactive, like potassium-40, K40. )   Also depleted from the radioactive core is radiocesium.   The half-lives of the radioactive isotopes of cesium are respectively for Cs134, Cs135 Cs136 Cs137, are respectively, 2.05 years, 3 million years, 13 days, and 30.02 years.    Cs134 is not a fission product generally, the chief fission isotope at mass number 134 is an isotope of xenon,  but is formed from the only stable, non-radioactive isotope of cesium, Cs133, which is a fission product, by neutron capture.  Cs135 is often generated in relatively low concentrations because its (transient) parent nuclide,  Xe135 has one of the highest neutron capture cross sections known, resulting in its transformation into Xe136, which was long regarded to be a stable nucleus, although modern physicists, because of a physics punctilio concerning the nuclear stability rules, were suspected that it was a very weakly radioactive nucleus.  With very sensitive instrumentation, it is possible to detect radioactive decay in this "stable" isotope, Xe136 and the apparent half-life appears to be on the order of 1020 years.

Right here at DailyKos, after Fukushima I read a lot of stuff written by people about the ratios of cesium isotopes in the regions of the destroyed reactors.   Like much else that was written about Fukushima here, particularly by the members of the superstition, fear and ignorance squad that calls itself "nuclear free DKos" it consisted mostly of scientific howlers.   (Other howlers were written by that guy who says that nuclear energy has a "role to play" in the future, but it needs to be "safer," to which I respond, "safer than what?"  There are no 10 exajoule scale per year forms of energy, not coal, not gas, not oil, and not dams that are as safe as nuclear energy.   None.  Zero.)

Cesium is, however, a mobile (and sometimes even volatile) fission product.   Waste mentality type people have long considered how to dump cesium created in commercial nuclear reactors referring to it as "waste" - something I oppose because in the last several years I've come to understand this very precious element in new and exciting ways, especially the radioactive kind which could be used to solve major environmental problems that have nothing to do with nuclear power.   My problem with radiocesium is not that there is too much of it, but that there is not enough of it.   In any case an elegant solution for safely dumping cesium that would work very nicely - were it not a stupid thing to dump cesium - at all would be to make synthetic pollucite.   Pollucite is one of the most stable minerals known.   Some of the oldest rocks on earth, rocks in the Canadian shield that are close to 4 billion years old, contain pollucite.   Essentially there are no other rocks that have survived as long on earth as those that contain pollucite.

One of the ironies about the 4 billion year old pollucite is that it is unlikely to survive humanity.   Pollucite ores in Canada are already mined to obtain cesium, and the chief use of cesium today is to make lubricating agents for oil and gas drilling, including the infamous "fracking" schemes that all of our anti-nukes endorse, tacitly (sometimes via deliberate or static ignorance) or openly.   By the way, all of the 4 billion year old pollucite is radioactive since pollucite contains both non-radioactive cesium and its cogener rubidium.   All of the rubidium on earth - except for some obtained in an isotopically pure form created by letting radioactive krypton, Kr85 decay into rubidium 85 that contains no Rb87 - contains Rb87 which is radioactive, but has a sufficiently long half life to have survived since the time at which the Earth formed.  

Unicellular life forms that were present at the time that the Oklo reactors were operating seemed not to have thought of making synthetic pollucite to contain the radiocesium for all of eternity, and the cesium seems to have leached out of the Oklo fossil reactor cores.   There is considerable evidence however that the process was very slow, and even incomplete.   None of the radiocesium survived:  It has all decayed to isotopes of barium.   Because of the wide distribution of the half lives of radiocesium, we can measure the leach rates of cesium by looking at the distribution and distance from the cores of barium isotopes.    The earliest leaching cesium would leave fossils of  Ba137 and  Ba134, whereas the last cesium to leave would leave the radiofossil  Ba135.   Some work like this has been done, but it is incomplete thus far.

One reference for these types of studies is Geochimica et Cosmochimica Acta 72 (2008) 4123–4135, "Ba isotopic signature for early differentiation between Cs and Ba in natural fission reactors."

I very much doubt that if the cesium leached a long way - and maybe it didn't - that it would have been in a concentration that in modern times would be considered particularly hazardous.   This is because any leaching would have taken a very long time, probably so long that all of the cesium-137 would have decayed to barium, leaving only the radioactive cesium-135 which has a relatively low specific activity and which necessarily would be further diluted by the very water flows that caused it to move in the first place.    It may not have even been comparable to in radiological concentrations to the radioactive potassium at that time, since the half-life of K40 is 1.227 billion years, meaning that two billion years ago, potassium was, by appeal to the radioactive decay laws, 3.1 times as radioactive as it is today.

Some years back I noted in this space that as a result of nuclear weapons testing, as well as Chernobyl, that Cs-137 is now widely distributed on earth.   Every Cloud Has A Silver Lining, Even Mushroom Clouds: Cs-137 and Watching the Soil Die.  We know a lot from modern experience how cesium behaves in the geosphere and atmosphere and it moves surprisingly slowly in many types of systems.  

It is a matter of some irony that since the wide distribution of Cs137, mostly in the 1940s, 1950s and 1960s, that worldwide human life expectancy has increased dramatically.   This of course is most likely not because of such distribution and is probably in spite of such distribution, although the increase in life expectancy obviously places some restrictions on the magnitude of the planetary toxicology of Cs137.

Today many places where radiocesium is leaching underground are known, most famously in the United States, from the Hanford "waste" tanks, mentioned at the opening of this diary, where the by products of the extraction of plutonium for nuclear weapons was dumped for several decades without much consideration for their composition.    There are also known comparable sites in the former Soviet Union and elsewhere.   These migrations are being exhaustively monitored, and many thousands of papers on the migration of cesium in the geosphere/atmosphere/hydrosphere/biosphere have been written and I have personally read lots of them.   They're very interesting things to read when you have nothing else to do during a bout of insomnia.

In any case it is clear that the majority of stuff that leached out of the pitchblende uranium ores that went critical about 2 billion years ago was cesium.   Nothing else went all that far, not even, surprisingly, the pertechnate ion.

I've gone on a quite a length about the nature of the fission products at Oklo and one of these that I haven't mentioned, Sm149 has been studied extensively by theoretical physicists in connection with ascertaining whether important physical constants, the fundamental constants are, as described in the title and opening paragraphs of this diary, are in fact, constant.

What are the "fundamental constants?"

They are a set of "constants" that are required for the standard model of physics which seeks to integrate the electromagnetic, weak nuclear force and the strong nuclear force.  They can be abstract, but in some cases, they show up in every day life.   The following quotation is taken from a recent paper Nuclear Physics B (Proc. Suppl.) 203–204 (2010) 3–17 entitled "The fundamental constants in physics and their possible time variation."

The 28 fundamental constants, which appear in the basic laws of physics, are not understood, but they are important parameters, relevant for all fields of physics, e.g. particle physics, astrophysics, cosmology, nuclear physics, solid state physics, atomic physics or laser physics. But they are also relevant for chemistry or biology. In chemistry and biology only the seven constants, relevant for the stable matter in the universe, play a role. These are Newtons gravity constant G, the fine structure constant, the mass of the electron, the QCD scale parameter and they masses of the light quarks u, d and s. In particle physics many more parameters enter, which are related to weak decays or to unstable particles – in total one has 28 fundamental parameters.
The rest of this admittedly too long diary will address the fine structure constant, usually designated a α.   I made a somewhat sarcastic reference to this constant in an earlier diary in this space, Oh. Oh. Plutonium Contamination Suspected.  In any case it is this constant, α whose drift has been evaluated by appeal to the operations of the Oklo natural nuclear reactors.

That the fundemental constants might drift was originally a speculation of the great Swiss/English/American physicist Paul Dirac who posited a law that can be stated this way:

Any two of the very large dimensionless numbers occurring in Nature are
connected by a simple mathematical relation, in which the coefficients are
of the order of magnitude unity.
(cf. Prog. Theor. Phys. 126 (2011), 993-1019)   This speculation lead to a further speculation that the fundamental constants might not be constant and a great many scientists have searched the universe, literally, as much of spacetime that is accessible to human vision, to confirm or deny this possibility, which is potentially of huge theoretical portent.  

A physicist named Shlyakhter proposed that the drift of the fine structure constant should be discernable by examining the amount of an isotope of Samarium, Sm149 present in the fossil reactors.   Over the years, many considerations of the neutronics of these reactors have been undertaken is a spectacular multidisplinary undertaking in which geologists, nuclear chemists, nuclear engineers, theoretical physicists and geochemists have participated.

A seminal paper was written by Freeman Dyson,  of the Institute of Advanced Study (he was recruited by Robert Oppenheimer to take the job) one of the most important physicists never to have been awarded the Nobel Prize - Nobel Laureate Steven Weinberg has described the Nobel Committee as having "fleeced" Dyson by not awarding Dyson the prize - Dyson showed how the distribution of samarium at Oklo was related to the historic (2 billion years ago) value of the fine structure constant, via an appeal to the Breit-Wigner formulation for neutron capture resonances.  

Here is a interview with Freeman Dyson discussing Samarium-149 and the Oklo reactors

Dyson, who is now approaching 90 is something of a strange bird:   Despite more than 50 years at the Institute of Advanced Study - which was of course, the last institution at which Albert Einstein worked, and is today is the home institution of people like Andrew Wiles - Dyson never actually bothered to get a Ph.D. but became an important physicist anyway.  Dyson did much in the physics community to point out the importance to physics of Richard Feynman's work on quantum electrodynamics, an area in which Dyson did much work himself.  By using a passive, unemotional voice, he convinced the American military establishment to not use nuclear weapons in Vietnam by claiming that it would be bad strategically. Indeed.

For much of his career on the side he was one of the dying breed - common in the middle of the twentieth century - of techno-utopians  who pushed for space flight to Mars and Saturn using nuclear explosions to propel ships and proposed designing genetic material for species that could survive on the surface of comets.  

Dyson, with the nuclear engineering pioneer Alvin Weinberg - who has almost saintly status among modern advocates of nuclear energy - was a pioneer in the theory of global climate change even though he has become a bête noire among modern climate activists for his contention that even if climate change is real - this is his claim and certainly not mine -it's not so bad and ought to be more or less ignored, maybe even encouraged.  (For these reason he and James Hansen have exchanged some rather nasty insults for one another.)   A liberal Democrat, Dyson was an enthusiastic supporter of Barack Obama, but was dismissive of Al Gore...

Here's a New York Times Magazine Profile of Freeman Dyson and some of the controversy surrounding him.

Irrespective of these controversies, Dyson showed that the fine structure constant could not have varied by more than -0.9 X 10-7 and 1.2 X 10-7 over the last 2 billion years, adding to his list of prodigious intellectual achievements.

The Oklo reactors have generated a lot of interest for a lot of reasons in a number of disiplines.  Besides showing the behavior of fission products on billion year time scales, they offer real insight to the history of the universe as a whole, as well as the history of the earth.

The reactors were discovered, by the way, when French uranium mining engineers discovered that the uranium at Oklo would prove pretty much useless for nuclear power plants of their time (this was in the early 1970's), owing to the depletion of U235 in the ores, which had fissioned in nuclear reactors two billion years before.   While this may have proved a disappointment to the mining officials, it has proved to be a boon to scientific understanding.

Interesting I think.

Have a nice evening.

Originally posted to NNadir on Sun Feb 19, 2012 at 12:36 PM PST.

Also republished by Nuclear dkos, Kosowatt, and SciTech.

Poll

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Comment Preferences

  •  Leaching radiocesium causing mutant unicellular (6+ / 0-)

    ...species to evolve, creating even more dangerous oxygen in the atmosphere, long drawn out discussions of uninteresting fission products, isotopically weird lanthanides, especially samarium but also lutetium, the mere mention of lutetium, natural nuclear reactors, hidden stuff in the rocks, pollucite mining, the hidden stories of rocks, other hide rates, and regularly cycling hot steamy natural nuclear reactor heated troll rates all go here.

  •  Rb-87 (4+ / 0-)
    Recommended by:
    NNadir, AaronInSanDiego, jabney, palantir

    I was interested to discover recently that Rb-87 is the source of about 10% (1Bq/litre) of the natural radioactivity of seawater. Nearly all the rest, of course, results from potassium (K-40).

  •  On Comments and recs at DK4 (13+ / 0-)

    Hi,

    Just for your info, under this new format there is a strong inverse correlation between effort expended in a a diary and number of recs, TJ and comments.   Readership for complex thoughtful diaries, whether the detail is technical or personal just isn't here any more.

    My last diary reflected two weeks of personal interaction with a talk show host in San Diego, and attendance at a Senior Expo that was being turned into a right wing venue by the new owner of the areas sole newspaper.  And I was interacting, challenging this personally.

    A dkos diary I wrote was ridiculed on naitonal radio, and I responded at the exposition.  Real, live, exclusinve news....yet, not a single comment and a few recs.  I no longer care, as I have to find other ways to do what I want to do.  I wish there was more interest, but the national attention span is declining.

    It bothered me that not a single person wrote a comment on something that was personally important, and had political currency.

    But, that's what this site seems to have become.  I feel a loss here myself, but have to find a way to continue the activities that interest me.  

    •  Believe me, I don't write diaries for recs. (11+ / 0-)

      This diary is a rambling mess, but I learned a lot writing it, since it required me to review some papers and topics I haven't looked at for a long time.

    •  Not necessarily (8+ / 0-)

      My long, technical diaries on the Higgs boson got hundreds of comments and recs, and were at the top of the rec list for most of a day.   I don't think it is length or technical detail that is relevant.   It could be time of day.

      I just read your series and found them really interesting.   I have no clue as to why they didn't get more recs.....maybe something else happened at that time?   Maybe Valentine's Day isn't the best time.   I'm at a loss to understand why some diaries get lots of attention and others don't.

      This diary was of some interest to me, since I'm very familiar with the physics (and the Oklo reactor), but it is probably too long for a casual reader.

      •  This diary didn't explain the role of iron (9+ / 0-)

        in the containment of technetium and uranium in the vicinity of the ore body. Because the host rock contains reduced, ferrous iron - mobile hexivalent uranium and pertechnetate ion are reduced to insoluble +4 oxidation states.

        The 2 billion year immobilization of uranium and technetium was not a matter of mere chance. It's related to how the ore body accumulated uranium in the first place.

        look for my eSci diary series Thursday evening.

        by FishOutofWater on Sun Feb 19, 2012 at 03:05:34 PM PST

        [ Parent ]

        •  Please elaborate... (0+ / 0-)

          NNadir seems to be telling us that we have nothing to fear from nuclear wastes even if buried in a porous sandstone aquifer, unencapsulated and bathed in flowing groundwater, because the radioactive materials will travel no farther than they did at Oklo over billions of years.

          But FishOutofWater seems to say that there is something special about the rocks at Oklo.  When disposing of unencapsulated nuclear waste, your neighborhood porous sandstone aquifer might not be as inherently safe as the Oklo sandstone.

          As long and informative as this diary has been, evidently there is more to be said.

          •  You may have misinterpreted what I said. (0+ / 0-)

            I am not recommending "disposal" of used nuclear fuel in porous sandstone or any other type of formation.

            I don't even consider that "nuclear waste" exists.   I am fully satisfied - after much hard work - that all of the constituents of used nuclear fuel are incredibly valuable.

            I am simply noting that the risk of nuclear energy even in the worst case is smaller than is associated with all other forms of energy and that an engineered isolation system, in which case should be at best temporary, will never under any circumstances as the status quo.

            •  Well, "storage" rather than "disposal," (0+ / 0-)

              if you prefer.  Complete recycling of used nuclear fuel, to the point where no radioactive hazard remains, will not be achieved for some years, if ever.  And if you are right about its value, much will be hoarded rather than recycled.  

              Until it's all gone, it needs to be kept safely contained.  You suggest that little special care is needed because radioactive materials did not travel far from the natural reactors at Oklo.  So, I am curious whether the Oklo sandstone is unusual or unique in its ability to retain radioactive products, or whether such sandstone is typical or ubiquitous.

              •  It IS safely contained. (1+ / 0-)
                Recommended by:
                bryfry

                If it were not safely contained, someone would be injured by it.

                The notion that nuclear materials need to be contained safely is rather absurd given the fact that dangerous fossil fuel waste - which kills two million people per year - is not contained and actually kills people.

                What exactly are you after?

                Assurance that nuclear energy needs to be perfect for zillions of years while nothing else can be perfect for the next 50 seconds?

                I object to the criteria.

                There are no forms of energy that can meet the arbitrary criteria set for nuclear energy.    None.  Zero.

                If we cared about "waste" - then the oil, gas, and coal industries would need to close immediately.

                If we cared about cost, the solar and wind industries - which by the way depend on the gas industry - would be gone.

                If we cared about sustainability no other industry could do what the nuclear industry could do if you study the case.

                The contempt for the nuclear industry and nuclear technology is totally a function of persistant and obnoxious myths.    They are no more relevant to reality than myths about Apollo or relevant to the rising of the sun.

                •  Until recently, waste of every kind (0+ / 0-)

                  was spewed everywhere without restraint.  We suffer the consequences now, and perhaps forever.

                  If humans have any capacity to learn from the mistakes of the past, then we should know by now that practically all the works of man need to be contained safely.

                  As my mother always said, "If Mr. Peabody's coal company jumped off a cliff, would you do it too?"  (ok, those might not have been her exact words - my memory is not what it used to be.)

                •  btw, I don't see where in my comments (0+ / 0-)

                  you find "contempt for the nuclear industry and nuclear technology."    

                  •  If I implied that I was specifically referring to (2+ / 0-)
                    Recommended by:
                    bryfry, eigenlambda

                    you in referring to contempt for the nuclear industry, I apologize, and my personality is not big on apologetics.

                    The general reference is however to the contention that any radiation related health at any time issue outweighs any other energy related health issue is absurd.

                    This, however, is the cultural way we see it, and in referring to questions of whether we can deal with every last radioactive atom forever, well in context of our current times, the question is absurd.

                    We can arbitrarily make nuclear energy as risk free as we wish for as long a period as we wish to do so, however in a rational culture, we would weigh cost/benefit ratios.  

                    I dealt with this question five years ago, in a diary in this awful space, where everyone thinks they're going to be driving solar powered cars to solar festivals.

                    Radioactive Isotopes from French Commercial Nuclear Fuel Found In Mississippi River.

                    Here's what I said at the conclusion:

                    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.

                    •  Thanks for clarifying. (0+ / 0-)

                      You have almost convinced me.  

                      What's missing, for me, is a convincing engineering solution to the recycling / storage / disposal problem. That solution, like cheap energy from fusion, always seems to be 20 years in the future. Your diaries have given me hope that there can eventually be an acceptable solution, but we are not there yet.

    •  I didn't comment on that, since (3+ / 0-)
      Recommended by:
      palantir, arodb, kurt

      I didn't feel I had anything to say.

      "Okay, until next time. Keep sending me your questions, and I will make fun of you... I mean, answer them." - Strong Bad

      by AaronInSanDiego on Sun Feb 19, 2012 at 02:57:24 PM PST

      [ Parent ]

    •  Maybe your title didn't pull readers in. (0+ / 0-)

      I'd rather have a buntle afrota-me than a frottle a bunta-me.

      by David54 on Sun Feb 19, 2012 at 07:09:47 PM PST

      [ Parent ]

  •  A word about jargon... (7+ / 0-)

    Just for the record, pretty much by definition, an equilibrium is a reversible process.  No radioactive decay process is reversible, and thus, calling the constant ratio of U-234 to U-238 an "equilibrium" is a misnomer.  In fact, the proper term is "steady state."

    I know, I know, you're just reporting the term used in the literature, but to me, this is just further evidence that physicists are clueless about some fairly basic concepts...

    -5.13,-5.64; If you gave [Jerry Falwell] an enema, you could bury him in a matchbox. -- Christopher Hitchens

    by gizmo59 on Sun Feb 19, 2012 at 01:48:51 PM PST

    •  Well, I don't get into those chemist/physicist... (6+ / 0-)

      ...arguments too much, although I have been into making engineer jokes.

      But to tell the truth, if I had a do over in life, I'd be an engineer.

      •  How do we know that God was an engineer? (16+ / 0-)

        When designing the human, who else would build a hazardous waste pipeline through a recreational area.

      •  You can do both: chem engineering. (1+ / 0-)
        Recommended by:
        NNadir

        Although a chemist I once knew loved to tell stories of the ineptitude of chem engineers. However, I have a son who is a chem engineer now and naturally enough I think he's plenty "ept".

        Moderation in most things.

        by billmosby on Mon Feb 20, 2012 at 06:09:23 AM PST

        [ Parent ]

        •  And for fluid phase reactor kind of people... (1+ / 0-)
          Recommended by:
          billmosby

          ..."nuclear chemical engineer."

          Now that would be a great field.  

          I've tried to study it on my own, since there seems not to be a formal program associated with it.

          •  Remember the old "OMRE" experiment? (1+ / 0-)
            Recommended by:
            NNadir

            Organically Moderated Reactor Experiment, I think it stood for. Turned out to be a great way to make tar in a hurry if I remember correctly.

            I couldn't find that, but I did find this, on a similar thing called Piqua Nuclear Power Facility. It mentions neutron-induced polymerization of the terphenyl coolant/moderator.

            Seems they still use some of the old plant buildings for warehouse and office space for the city it was located in, Piqua, OH. I'm suddenly getting images of the "Parks and Recreation" TV show in my head....

            Moderation in most things.

            by billmosby on Mon Feb 20, 2012 at 05:58:21 PM PST

            [ Parent ]

            •  Actually there was a lot of tar like material... (1+ / 0-)
              Recommended by:
              billmosby

              ...at Oklo.

              I didn't mention it in the diary, because it was already way too long.

              I would imagine that you have read Weinberg's "The First Nuclear Era."

              We hear about Weinberg and the MSR, but that in my mind misses the point of who he was.    He was just pouring forth with lots of approaches to reactors, and the MSR was just one of many fluid phase ideas he had.

              I always try to keep not his single MSR idea in mind, but his creativity.

              The last word has not been written on organic phase nuclear reactors, if at least, the last word has not been written on humanity itself.

              •  Argonne had a family tree of reactors. (1+ / 0-)
                Recommended by:
                NNadir

                That lab was charged with coming up with ideas in the early days, and also with building prototypes of many of them. A number of them were at INL, there were 49 built there altogether by various organizations if I recall correctly.

                I remember a nicely framed family tree chart of reactors hanging on a wall somewhere at Argonne-West, but it doesn't show up in a google image search. Dates from the early 50s, I think, and it had a couple or three dozen types on it.

                Moderation in most things.

                by billmosby on Mon Feb 20, 2012 at 06:39:26 PM PST

                [ Parent ]

                •  Man, that would be a cool thing to see that (1+ / 0-)
                  Recommended by:
                  billmosby

                  chart.

                  To tell the truth though, it's easy to imagine even today lots of kinds of reactors, particularly because we know so much more about material science than we did then.

                  I remember that Bruce Hogland had on his website - I think it was him - some calculation in which he considered there were 900 types of reactors.   He did a combinatorial type of calculation involving coolants, moderators, so on and so on.

                  I recall thinking to myself that he missed some.

                  The high temperature ideas are the ones that really seem exciting.   So much could be done, if we didn't live in times of fear, ignorance and superstition.

                  •  Here's something about the early days at INL.. (1+ / 0-)
                    Recommended by:
                    NNadir

                    It shows something of the variety of designs built and tested there, starting the year I was born.

                    Proving the Principle.

                    It's in chapters, each one a pretty sizeable pdf. The physical book is on Amazon, I see. I got a copy for free when it came out, as a 50th anniversary present; all INL employees could get one. I remember a big celebration in the minidome in Pocatello. Idaho Governor Cecil Andrus came by and gave a speech in which he excoriated us for the emerging waste problems at the Site.

                    Moderation in most things.

                    by billmosby on Mon Feb 20, 2012 at 07:35:20 PM PST

                    [ Parent ]

            •  There was an organic cooled reactor (2+ / 0-)
              Recommended by:
              billmosby, NNadir

              built in Canada. See
              http://media.cns-snc.ca/...

    •  The dictionary definition of equilibrium (2+ / 0-)
      Recommended by:
      Deward Hastings, palantir

      says nothing about a reversible process, except in the context of chemistry.

      "Okay, until next time. Keep sending me your questions, and I will make fun of you... I mean, answer them." - Strong Bad

      by AaronInSanDiego on Sun Feb 19, 2012 at 02:46:25 PM PST

      [ Parent ]

    •  Secular equilibrium (2+ / 0-)
      Recommended by:
      palantir, eigenlambda

      has a specific definition.

      look for my eSci diary series Thursday evening.

      by FishOutofWater on Sun Feb 19, 2012 at 03:07:07 PM PST

      [ Parent ]

    •  kind of (2+ / 0-)
      Recommended by:
      gizmo59, bryfry

      it's a real equilibrium because as A decays into B, the population of A decreases.  That's the force in the other direction, so that the derivative of the population of B really can go to 0 in a finite amount of time.  Contrast this with the case where the daughter nucleus is more stable, there can be no equilibrium there.

      Also, it would be cool if years ago people had known what was happening and listed time constants for radioactive decays instead of half-lives.  To avoid those awkward factors of .69.  

      Global warming is the inconvenient truth, nuclear power is the inconvenient alternative.

      by eigenlambda on Sun Feb 19, 2012 at 04:32:33 PM PST

      [ Parent ]

      •  In a real equilibrium, (2+ / 0-)
        Recommended by:
        eigenlambda, kurt

        B would be able to get back to A:

        A <----->  B

        And over time, the amounts of A and B would not change.

        The process described is:

        A  ------>  B  ------>  C, etc.

        It makes perfect sense that the amounts of A and B should be related, but that relation is kinetic in nature.  This is why chemists call such situation a steady state rather than an equilibrium.  The amounts of substance are ultimately changing in one direction only, but there is an easy way to predict the amount of intermediate (B).

        By the way, I am in complete agreement with using natural lifetimes or rates of decay rather than half-lives, but we have this opinion because we grew up in the age of the calculator and the computer.

        -5.13,-5.64; If you gave [Jerry Falwell] an enema, you could bury him in a matchbox. -- Christopher Hitchens

        by gizmo59 on Sun Feb 19, 2012 at 05:17:24 PM PST

        [ Parent ]

  •  good point, giz: and i love NNadir's diaries, (2+ / 0-)
    Recommended by:
    palantir, kurt

    I don't know how he finds the time to write them, I barely have time to read them. Two more years 'til retirement, than.

    Um, NNadir, yer the best!

    equilibrium notequal steady state.

    " In England, any man who wears a sword and a wig is ashamed to be illiterate. I believe it is not so in France" Sam. Johnson, per Boswell

    by Mark B on Sun Feb 19, 2012 at 02:21:51 PM PST

  •  We looked for evidence in Australia (4+ / 0-)
    Recommended by:
    palantir, eigenlambda, Mathazar, kurt

    of a natural reactor but the concentrations of rare earth elements that poison nuclear reactions was too high. Los Alamos found very small but significant levels of natural plutonium.

    look for my eSci diary series Thursday evening.

    by FishOutofWater on Sun Feb 19, 2012 at 03:59:25 PM PST

  •  Uranium, thorium, and the rare earths aren't (5+ / 0-)
    Recommended by:
    palantir, bryfry, PrahaPartizan, kurt, NNadir

    soluble in iron or silicon, so they hang out together.  Uranium and thorium are found in rocks in the tetravalent state.  When the cyanobacteria decided to radically alter the chemistry of the atmosphere, the uranium with its 2 extra electrons over thorium became hexavalent and washed away into the ocean; it could then be deposited from the ocean in phosphates.

    This just-so story explains why thorium is found with rare earths and uranium is found in the ocean and in phosphates XD theres a video that goes into thorium geochemistry here -> http://www.youtube.com/...

    Global warming is the inconvenient truth, nuclear power is the inconvenient alternative.

    by eigenlambda on Sun Feb 19, 2012 at 04:18:16 PM PST

    •  Uranium, thorium, K & Rare earths (5+ / 0-)
      Recommended by:
      eigenlambda, bryfry, PrahaPartizan, crose, kurt

      are LILs - Large Ion Lithophile elements. The large ions don't fit well into the densely packed mantle minerals so they preferentially fractionate int melts that rise up into the crust. Thus the earth's crust is enriched in uranium and thorium compared to the mantle and core.

      look for my eSci diary series Thursday evening.

      by FishOutofWater on Sun Feb 19, 2012 at 07:02:14 PM PST

      [ Parent ]

      •  wow potassium, the stuff that turns granite pink (1+ / 0-)
        Recommended by:
        PrahaPartizan

        granite has the stuff that didn't be part of the mantle or oceanic crust.

        According to Wikipedia, http://en.wikipedia.org/...

        LILEs come from the first two columns, which totally makes sense, and their ionic radii appear to be above around 150pm.  Meanwhile, uranium has an ionic radius comparable to calcium, but along with thorium, tantalum, and the rare earths, it's a "high field strength element" with a charge of >+2.  

        http://en.wikipedia.org/...

        Aluminum, at +3, doesn't fit this rule, but it's also tiny.

        Global warming is the inconvenient truth, nuclear power is the inconvenient alternative.

        by eigenlambda on Sun Feb 19, 2012 at 07:51:24 PM PST

        [ Parent ]

    •  Iron though, forms a nice fluid eutectic... (2+ / 0-)
      Recommended by:
      billmosby, eigenlambda

      ...with plutonium.

      This troubled early reactor designers quite a bit.

      Plutonium is a magnificiently unorthodox kind of element, and it's appropriate that it's named for a planet that's not a planet.

      •  I seem to recall a story from Argonne-West (1+ / 0-)
        Recommended by:
        NNadir

        in which some molten Pu in a lab ate its way through something or other (a stainless steel tabletop?) due to that effect. Since EBR-II emphasized metallic fuel containing Pu jacketed in SS alloys which contained iron, they were always careful to avoid temperatures at which that would happen. I believe the sodium boiling temperature is lower, so that by designing the system to avoid that you also avoided the eutectic problem. Not sure about that, though.

        Moderation in most things.

        by billmosby on Tue Feb 21, 2012 at 05:19:23 AM PST

        [ Parent ]

        •  That's certainly believable. Steels and... (1+ / 0-)
          Recommended by:
          billmosby

          ...and metallic molten plutonium don't get along.   Off the top of my head, without looking it up, I believe the eutectic has a melting point of around 600C.

          Of course, the other side of this coin is that this eutectic in the right setting could be quite useful.

          •  I think you're right, (1+ / 0-)
            Recommended by:
            NNadir

            although the boiling point of Na seems to be listed as 883 C, so I guess my previous conjecture is wrong. Maybe the fuel alloy was such that a higher temp was ok. It would have been something like U 10 Zr 20 (I'm seem to remember) Pu + higher actinides after a few cycles, at least in the rather small EBR-II core which needed 67% enriched U. For a bigger core the Pu percentage would have been smaller. Or maybe the Pu percentage would have been higher than 20 for EBR-II if a DU-Pu fuel had been contemplated, but as it was a research reactor they didn't have a need to run it without U-235 as perhaps a breeder would have to in the very long run.

            Anyway I know they ran the reactor at a peak core temp of 704 C (1300 F is given in the link, hope my math is good.. )without any problems (link, about halfway down, search on "higher than for normal operation").

            Moderation in most things.

            by billmosby on Tue Feb 21, 2012 at 07:32:14 AM PST

            [ Parent ]

            •  Well, I don't have the direct experience... (1+ / 0-)
              Recommended by:
              billmosby

              ...you have, but I believe that Zr was added to the fuels to prevent formation of eutectics.

              One fun thing about plutonium alloys is how awfully complex their phase diagrams can be.

              You know, I'll piss off thorium guys if I say too much about sodium cooled reactors that is positive.

              In truth, I'm not a sodium kind of guy.  

              If I had to pick something, I'd go with lead alloys, although not necessarily the traditional (Soviet) lead/bismuth alloy.

              •  Pb, me too. I wonder why they didn't (1+ / 0-)
                Recommended by:
                NNadir

                use that in the first place. Maybe because they have a fear of letting things go solid and lead takes a higher temp to keep molten? EBR-I used NaK, which doesn't freeze until about 10 F. Which of course you can easily get to in an Idaho winter, but not indoors with a reactor so much...

                Reminds me-- the electrorefiner which Argonne-W (now Materials Processing something or other) has operated since before 2000 sometime has been continually kept above 1000 C from then to now. Used to continue the reprocessing research...er.... to condition the ANL-W inventory of spent fuel into something a little more easily storable. Operated, along with ancillary equipment, in the same old donut-shaped hot cell facility attached to the EBR-II containment building that EBR-II's original reprocessing equipment operated in from '64 to '69.

                Moderation in most things.

                by billmosby on Tue Feb 21, 2012 at 08:34:05 AM PST

                [ Parent ]

                •  It probably had to do with the consideration (1+ / 0-)
                  Recommended by:
                  billmosby

                  of freeze outs, as you say.

                  I believe the Soviets had some problems operationally with that.

                  A bismuth eutectic was designated of course to lower the melting point.   The down side of this of course, was the accumulation of Po210, even though the Soviets, and later the Russians have been able to sell on the world market all that they can get out of their reactors, for antistatic devices, medical uses, etc.

                  The Russians also used Po210 to kill a renegade intelligence officer who'd defected to the West, which is almost certainly the only incident of the much ballyhooed "nuclear terrorism" that actually played out.   I'm sure the Russians chose this method to assure everyone that this was their calling card.   Pooty Poot is a tough guy.

                  I've been thinking though of all kinds of other lead alloys with very interesting properties, as well as some relatively novel (as far as I can tell) reactor designs to use these alloys.   Again, it's the spirit of Weinberg, though it sounds like things were very creative at INL in the first nuclear era as well.

                  •  For any heat transfer fluid that freezes at more (1+ / 0-)
                    Recommended by:
                    NNadir

                    than about 30 °C, freeze out is going to be an issue. I would expect the designers of any system (nuclear or otherwise) using such a fluid will put in some sort of auxilliary heater for startups. Does anyone know the details of what is done in such cases?

                    •  I believe, but am not certain, that on Soviet (1+ / 0-)
                      Recommended by:
                      eigenlambda

                      submarines, they had electric heaters.

                      Of course after the reactor has run for a while, the decay heat is substantial in the fuel.

                      I'm sure I have in my notes somewhere, the melting point of Pb/Bi coolant, which was fairly low.

                      I'll try to look it up tomorrow.

                      •  The melting point (2+ / 0-)
                        Recommended by:
                        NNadir, eigenlambda

                        of Lead Bismuth Eutectic (LBE) alloy is fairly low (397 K, vs. 371 K for sodium), but if I recall correctly, one of the attractive features of LBE is the large difference between its melting point and its boiling point -- a difference of 1546 K for LBE, vs. 785 K for sodium, vs. 100 K for water at atmospheric conditions.

                        I can't speak for soviet submarine reactors, but I do know that the French sodium cooled reactors had electric heaters embedded in the surrounding concrete structure to keep the sodium in a liquid state or to re-melt solidified sodium coolant.

                        Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.
                        -- Albert Einstein

                        by bryfry on Wed Feb 22, 2012 at 10:33:02 AM PST

                        [ Parent ]

                        •  The other attractive feature of LBE has to do (2+ / 0-)
                          Recommended by:
                          bryfry, eigenlambda

                          do with water of course.

                          That higher temperature range is a very good thing of course.  

                          A few weeks ago I was checking out the vapor pressure of molten lead, which is quite significant actually.

                          Here's a nice recent Russian reference for the vapor pressure in the lead/gallium system:  

                          Russian Journal of General Chemistry, 2011, Vol. 81, No. 1, pp. 27–32.

                          Actually there's a whole world of lead alloys, and some of them have been investigated extensively for reasons that have nothing to do with nuclear energy.

                          In the past, of course, people thought of fast reactors at plutonium making machines with energy on the side.

                          Now my personal opinion is that the world needs more plutonium, not less of it, and sometimes I go as far as saying that plutonium, not the Th-232/U-233 system (and I hope I don't piss anyone off) is the real key to the immediate future.

                          That said, the high temperatures are very, very, very attractive, maybe more attractive than simply making plutonium and a little electricity/desalinated water on the side.   It is possible to make syn gas directly, at least in my mind, from carbon dioxide and water, and there are even nicer variations of the "anything into syn gas" situation that are even more attractive.

                          This may be a purely aesthetic thing, but I never liked the bismuth alloy because over the long term, it tranmutes bismuth into lead at the historic concentrations, and not the other way around.   Other lead alloys, and even neat lead, on the other hand transmute lead into bismuth.    (Maybe though, I've been hanging out with anti-nukes too long to even care about this insignificant point.)

                          But as I see it, it turns out that other alloys have other advantages as well, particularly with metals that can do things other than heat transfer, catalysis for instance.

                          If it were up to me, I wouldn't lose too much sleep over this solidification issue.    You can, I think, design away this problem, or at least I think you can.   The Prandtl number of lead is very low, and its not like you're going to live by convection in these kinds of systems anyway.

                          A potential problem, at least a potential problem in the interesting and curious minds of anti-nukes, is the accumulation of Pb-205 over the years.   One could argue with them that lead is self-shielding, but they would probably cry about the matter any way.

                          It's interesting, but as I see it, lead in a neutron flux gets more and more transparent as it ages.

                          Pb-208 is a wonderful nucleus, I think, and it would offer one the infinite amusement of telling anti-nukes that nuclear energy can make all that lead they've been dumping in the atmosphere - while they wait for Amory Lovins' grand wind and solar future (that never comes) - go away and become future Peptobismol.

                          Of course this might upset them further.   After many and many and many decades of looking it turns out that all the Bismuth on earth is radioactive, albeit with a half-life longer than the age of the universe.

  •  Ok, that took a while NN :) (3+ / 0-)
    Recommended by:
    NNadir, FishOutofWater, kurt

    Well worth it though. I posted to SciTech. I hope you don't mind.

    I know how you feel about how few comments and recs your articles get. All too well. I note that in SciTech recs to views run about 20%. Very disappointing. Anyway, you can always count on me reading your stuff, 'cause, well, I learn about things. Thanks.

    •  No problem about Scitech. For the record... (3+ / 0-)
      Recommended by:
      palantir, bryfry, kurt

      ...many of my diaries have had lots of comments, but they weren't all, um, positive.  

      As for recs, I would probably take all that advice I've been given about "being nice" or "being polite" if I were really into recs.

      You know, for many years it was taken as a matter of course that if you were a political liberal, it followed that you were an anti-nuke, and in my opening remarks in this diary, I was just musing that my position to the contrary was obscure on this site when I joined it.

      It has been my pleasure to have had people tell me that I helped them to change their ideas about nuclear energy, and whether any one agrees or not, I believe that my abrasive style - which is something of an affectation in any case - did make some people think this stuff through.

      On the other hand, we know that some people will avoid thinking at any cost.

      I do worry though that in this country respect for science is sinking to new lows.    I wish I could say that only Republicans were participants in this sphere, but that is not the case.

      Thanks very much though for your kind words.

  •  Oklo 'reactor' was 0.01% of the power of a 1GW (0+ / 0-)

    reactor(industry standard), just 100 kw heat smaller than a 250cc dirt bike engine 20 hp assuming 20% efficiency.

    http://geology.about.com/...

    So Oklo is shows how natural nuclear power plants are?
    (snark)

    •  The 16 reactors operated for 500,000 years. (4+ / 0-)

      Actually, 250 cc dirt bikes are far more dangerous than American nuclear plants.

      According to the CDC in a four year period, 2001-2004, 245 people died, and 56,870 people were injured on dirt bikes.

      If nuclear power plants killed that many people in a similar period, all our our scientifically illiterate anti-nukes would be screaming loudly in the their cute and lovable fetishist style.

      I note that they never scream out loud about the two million people who die each year from dangerous fossil fuel and biofuel waste, and I assume that the CDC is not counting the number of people that dirt pike particulate pollution kills and injures.

      The dirt bike industry will never be as safe as the nuclear industry has been in it's roughly 55 year history.

      Thanks for offering me yet another opportunity to point up the mindless selective attention of anti-nukes.

      Have a great evening.

      •  Damn, you're right about dirt bikes. (1+ / 0-)
        Recommended by:
        PrahaPartizan

        They hurt and kill far more Americans than nuclear accidents.

        FWIW I tried hard to discourage my neighbors from continuing to let their little kids ride dirty bikes. It wasn't just the noise. I feared for the kids' safety.

        look for my eSci diary series Thursday evening.

        by FishOutofWater on Sun Feb 19, 2012 at 07:06:13 PM PST

        [ Parent ]

  •  Relax, dude. (0+ / 0-)

    I'd rather have a buntle afrota-me than a frottle a bunta-me.

    by David54 on Sun Feb 19, 2012 at 07:17:52 PM PST

  •  What scares people the most about nuclear power (2+ / 0-)
    Recommended by:
    DamselleFly, kurt

    isn't the idea that we could make it safe enough to  use on a wide scale, we probably could. If we weren't human society of the early 21st century. It's the duplicity and greed of people who have an interest in developing nuclear energy at the lowest possible cost whom people don't trust.

    I'd rather have a buntle afrota-me than a frottle a bunta-me.

    by David54 on Sun Feb 19, 2012 at 07:29:44 PM PST

    •  lowest possible cost?! are you kidding? (0+ / 0-)

      if they had to bring it in at a lower cost, I''ll bet they'd have a better design

      " In England, any man who wears a sword and a wig is ashamed to be illiterate. I believe it is not so in France" Sam. Johnson, per Boswell

      by Mark B on Sun Feb 19, 2012 at 07:45:27 PM PST

      [ Parent ]

    •  You've clearly (1+ / 0-)
      Recommended by:
      Mcrab

      watched too many episodes of The Simpsons.

      Do you also think that every convenience store is manned by an Indian immigrant named Apu?

      Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.
      -- Albert Einstein

      by bryfry on Sun Feb 19, 2012 at 08:34:26 PM PST

      [ Parent ]

    •  Point taken, except (2+ / 0-)
      Recommended by:
      gzodik, bryfry

      I would take issue and say nuclear plants are safe enough to use on a wide scale, just as automobiles and airplanes are generally considered "safe" despite the fact that people can and do still die in them. Also, newer plant designs are much safer than older designs, just as new cars and planes are safer than those from 50 years ago.

      I would not cynically frame the argument in terms of duplicity and greed. Nuclear plants are not run by your stereotypical used car salesmen, politicians and carnival barkers. But we do need to guard against hubris and ignorance. That is what strong regulations are for. Three Mile Island was ultimately the result of ignorance. The industry was still relatively new and few if any understood the importance of training, maintenance and information sharing, among other things The reactors at Fukushima, despite their age, survived the initial earthquake and should have been able to survive the tsunami had the sea wall been built high enough. The fact that it wasn't appears do be due to a regulatory structure in Japapn that was too fractured, culturally dysfunctional and complacent to establish and enforce adequate requirements based on the known risks.

      •  The facts of life in the fossil fuel industry (1+ / 0-)
        Recommended by:
        DamselleFly

        is what frames the issue in terms of duplicity and greed.
        I take the rest of your comment as support of what I wrote.
        It probably is theoretically possible to have safe nuclear power.
        If we didn't know what we know about  human beings, folks would be more enthusiastic.
        If we do go forward, here's how we should do it.
        Industry leaders should just accept the fact that there is going to be strict regulation rather than fight against it constantly and spend millions of dollars lobbying to get around it, as they do now with the fossil fuel industry.
        We should first come  up with a consensus plan about storage and security.
        We should then put our efforts into 4th gen reactor research and hold off on building a bunch of reactors until we have that capability.
        In the meantime someone is going to have to convince me that mining uranium is not an environmental/ worker safety disaster.
        Finally, we have all,  for decades subsidized nuclear research with our taxes. Nuclear power is a publicly held asset  owned by the citizens. There's room for some private profit, but let's not hear any crap about the "free market" or energy speculation.

        I'd rather have a buntle afrota-me than a frottle a bunta-me.

        by David54 on Mon Feb 20, 2012 at 05:07:25 AM PST

        [ Parent ]

      •  Or, rather, the fuel tanks, the cheapest (0+ / 0-)

        part of the plant, located behind the plant.

        D.

        Dr. Isaac Asimov: "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny ...'"

        by davidwalters on Tue Feb 21, 2012 at 06:21:45 PM PST

        [ Parent ]

    •  Agree (1+ / 0-)
      Recommended by:
      David54

      and one more thing.

      Lots of folks who would agree would still not want one in their backyard.

      I fall down, I get up, I keep dancing.

      by DamselleFly on Mon Feb 20, 2012 at 06:57:47 AM PST

      [ Parent ]

  •  Oklo! Thanks for this, NNadir. (2+ / 0-)
    Recommended by:
    bryfry, NNadir

    I always enjoy reading about this. And not just because I was born in "Oklohoma"....

    Moderation in most things.

    by billmosby on Sun Feb 19, 2012 at 09:03:12 PM PST

  •  Is lutefisk (1+ / 0-)
    Recommended by:
    NNadir

    made with cesium-137 hydroxide the ultimate weapon of mass destruction?

  •  Applications for Cs-137 (0+ / 0-)

    and other fission products.

    When you say that we don't have enough Cs-137, what applications do you have in mind for it? Besides making lutefisk slightly more dangerous, that is.

    I seem to recall someone mentioning Tc as an alloying metal for nuclear applications. Do you have any comments on that?

    •  I'm not sure which uses NNadir had in mind but (0+ / 0-)

      since Cs137 is a gamma emitter it can be used for anything other gamma sources like Co60 are used for eg:
      cancer therapy
      sterilizing medical equipment
      irradiating food to preserve it

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