Tuesday, April 7, 2015

70. The Periodic Table - chapter 18 - Uranium + Cadmium



Jump to Introduction + Chronology

Jump back to Previous: The Periodic Table - chapter 17

April 7, 2015



p191 One cannot employ just anyone to do the work of Customers’ Service. It is a delicate and complex job, not much different from that of diplomats: to perform it with success you must infuse faith in the customers, and therefore it is indispensable to have faith in yourself and in the products you sell; it is therefore a salutary activity, which helps you to know yourself and strengthens your character. It is perhaps the most hygienic of the specialities that constitute the decathlon of the factory chemist: the speciality that best trains him in eloquence and improvisation, prompt reflexes, and the ability to understand and make yourself understood; besides, you get a chance to travel about Italy and the world, and it brings you into contact with all sorts of people. I must mention another peculiar and beneficent consequence of CS: by pretending to esteem and like your fellow men, after a few years in this trade you wind up really doing so, just as someone who feigns madness for a long time actually becomes crazy.


I’m not going to relate the entire story but a buyer Levi calls on tells him a convoluted story from the war years about the Resistance and “Nazi aeronaut-astronauts” who gave him a lump of uranium. The buyer even sends him a piece of the “uranium” which Levi analyses. First he determines, by the weight, that it can’t be uranium.


p198 But if it wasn’t uranium, what was it? I cut off a slice of the metal with the handsaw (it was easy to saw) and offered it to the flame of the Bunsen burner: an unusual thing took place: a thread of brown smoke rose from the flame, a thread which curled into volutes. I felt, with an instant of voluptuous nostalgia, reawakening in me the reflexes of an analyst, withered by long inertia: I found a capsule of enameled porcelain, filled it with water, held it over the sooty flame, and saw form on the bottom a brown deposit which was an old acquaintance. I touched the deposit with a drop of silver nitrate solution and the black-blue color that developed confirmed for me that the metal was cadmium, the distant son of Cadmus, the sower of dragon’s teeth.


p199 ...It was clearly impossible to get to the bottom of it [why the buyer had started telling this story]: but I, tangled in the CS net of duties toward society, the company, and verisimilitude, envied in him the boundless freedom of invention of one who had broken through the barrier and is now free to build for himself the past that suits him best, to stitch around him the garments of a hero and fly like Superman across centuries, meridians, and parallels.

This is a repeated theme in this book -- how people invent their pasts.

In one of my many programming jobs, as a hired contractor who would come in to work on a specific problem and then leave when finished, there was a crisis (the details of which I can’t recall) in which the person directly above me found herself and her position totally compromised by some failure on her part -- things had not gone as she said they would and it was all on her. I was fascinated to see how, over a matter of mere hours, she revised -- in her head -- the morning’s event in such a way that she was not at fault and things were not as bad as it seemed.

I’ve written previously about the Battle of France, in 1940, but I don’t think I mentioned a detail from some British account I read. When liaison officers from the BEF staff first made contact with the staff of the French Army’s forward command, they found them to be in a kind of stupor, hardly able to respond to questions and seemingly out of touch with the state of events on the battle field. I’ve always attributed this to sleep deprivation (there are many accounts of commanders so sleep deprived that they would be walking around without being fully conscious) or else to the shock of facing a reality so at variance with what they had expected to see. But now I’m wondering if there might be still another factor, the cumulative effect of mentally re-writing reality, as my friend did in her office war. Could this, over time and as your private “reality” differed more and more from the actual reality around you, result in a state where your mind was completely dedicated (like the computer in The Restaurant At the End of the Universe attempting to brew a cup of proper tea) to managing a fictional reality that increasingly shares no points in common with the real world.


Unlike Levi, my father was a natural salesman. He loved to schmooze and I’m sure much of his work was done at bars at the end of the day. He, too, spent a great deal of time on the road, though in his case you need to substitute for Italy and “the world” first Kentucky, Tennessee, and Indiana; then Colorado, Wyoming, and Nebraska; then southern and central California; and finally the then fast growing state of Arizona.


What strikes me about both these cases -- my father's and Levi's -- is the disconcerting degree of normality of these careers. From growing up a Jew in Fascist Italy, and after miraculously surviving Auschwitz, to end up an every-day CS representative just seems surreal. My father’s case is not as extreme, but only in comparison. He spent almost the entire Pacific War deployed from Hawaii to the Philippines. After recovering from a broken back suffered in training, now a weapons platoon sergeant, he lived for months in the jungles of Luzon fighting against enemy troops commanded by one of Japan’s best generals (Yamashita). He returned to the States with both malaria and jaundice.

I suppose spending nearly the rest of his life driving around the American countryside behind a late model Chevy V-8, and with a company expense account, would have seemed like heaven, but what a dramatic change of gears for a person’s life.



Uranium (U 92)


...Uranium has the second highest atomic weight of the primordially occurring elements, lighter only than plutonium.[4]...


...Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years,[6] making them useful in dating the age of the Earth.


Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. While uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons, uranium-235 and to a lesser degree uranium-233 have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors, and produces the fissile material for nuclear weapons. Depleted uranium (238U) is used in kinetic energy penetrators and armor plating.[7]


Uranium is used as a colorant in uranium glass producing orange-red to lemon yellow hues. It was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the planet Uranus... Research by Enrico Fermi and others, such as J. Robert Oppenheimer starting in 1934 led to its use as a fuel in the nuclear power industry and in Little Boy, the first nuclear weapon used in war...


...Uranium metal has a very high density of 18,800 kg/m3, denser than lead (11,340 kg/m3), but slightly less dense than tungsten (19,300 kg/m3) and gold (19,320) kg/m3.
...
Depleted uranium is also used as a shielding material in some containers used to store and transport radioactive materials. While the metal itself is radioactive, its high density makes it more effective than lead in halting radiation from strong sources such as radium.[9] Other uses of depleted uranium include counterweights for aircraft control surfaces, as ballast for missile re-entry vehicles and as a shielding material.[10] Due to its high density, this material is found in inertial guidance systems and in gyroscopic compasses.[10] Depleted uranium is preferred over similarly dense metals due to its ability to be easily machined and cast as well as its relatively low cost.[14]The main risk of exposure to depleted uranium is chemical poisoning by uranium oxide rather than radioactivity (uranium being only a weak alpha emitter).
...
The main use of uranium in the civilian sector is to fuel nuclear power plants. One kilogram of uranium-235 can theoretically produce about 20 terajoules of energy (2×1013 joules), assuming complete fission; as much energy as 1500 tonnes of coal.[7]
...
Before (and, occasionally, after) the discovery of radioactivity, uranium was primarily used in small amounts for yellow glass and pottery glazes, such as uranium glass and in Fiestaware.[16]


The discovery and isolation of radium in uranium ore (pitchblende) by Marie Curie sparked the development of uranium mining to extract the radium, which was used to make glow-in-the-dark paints for clock and aircraft dials.[17] This left a prodigious quantity of uranium as a waste product, since it takes three tonnes of uranium to extract one gram of radium. This waste product was diverted to the glazing industry, making uranium glazes very inexpensive and abundant. Besides the pottery glazes, uranium tile glazes accounted for the bulk of the use, including common bathroom and kitchen tiles which can be produced in green, yellow, mauve, black, blue, red and other colors.
...
In 1972 the French physicist Francis Perrin discovered fifteen ancient and no longer active natural nuclear fission reactors in three separate ore deposits at the Oklo mine in Gabon, West Africa, collectively known as the Oklo Fossil Reactors. The ore deposit is 1.7 billion years old; then, uranium-235 constituted about 3% of the total uranium on Earth.[20] This is high enough to permit a sustained nuclear fission chain reaction to occur, provided other supporting conditions exist. The capacity of the surrounding sediment to contain the nuclear waste products has been cited by the U.S. federal government as supporting evidence for the feasibility to store spent nuclear fuel at the Yucca Mountain nuclear waste repository.[20]
...


Two fuzzy black features on a fuzzy white paper-like background. There is a handwriting at the top of the picture.
Antoine Henri Becquerel discovered the phenomenon of radioactivity by exposing a photographic plate to uranium in 1896
In 1841, Eugène-Melchior Péligot, Professor of Analytical Chemistry at the Conservatoire National des Arts et Métiers (Central School of Arts and Manufactures) in Paris, isolated the first sample of uranium metal by heating uranium tetrachloride with potassium.[22][25] Uranium was not seen as being particularly dangerous during much of the 19th century, leading to the development of various uses for the element. One such use for the oxide was the aforementioned but no longer secret coloring of pottery and glass.

Henri Becquerel discovered radioactivity by using uranium in 1896.[11] Becquerel made the discovery in Paris by leaving a sample of a uranium salt, K2UO2(SO4)2 (potassium uranyl sulfate), on top of an unexposed photographic plate in a drawer and noting that the plate had become "fogged".[26] He determined that a form of invisible light or rays emitted by uranium had exposed the plate.-Wiki


Cadmium (Cd 48)


This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it prefers oxidation state +2 in most of its compounds and like mercury it shows a low melting point compared to transition metals. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm)...

Cadmium occurs as a minor component in most zinc ores and therefore is a byproduct of zinc production. It was used for a long time as a pigment and for corrosion-resistant plating on steel, whereas cadmium compounds were used to stabilize plastic. The use of cadmium is generally decreasing due to its toxicity (it is specifically listed in the European Restriction of Hazardous Substances [3]) and the replacement of nickel-cadmium batteries with nickel-metal hydride and lithium-ion batteries. One of its few new uses is in cadmium telluride solar panels. Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.
...
Cadmium (Latin cadmia, Greek καδμεία meaning "calamine", a cadmium-bearing mixture of minerals, which was named after the Greek mythological character Κάδμος, Cadmus, the founder of Thebes) was discovered simultaneously in 1817 by Friedrich Stromeyer[12] and Karl Samuel Leberecht Hermann, both in Germany, as an impurity in zinc carbonate.[3] Stromeyer found the new element as an impurity in zinc carbonate (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, because it was found in this zinc compound. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. He was persistent in studying these results and eventually isolated cadmium metal by roasting and reduction of the sulfide. The possibility to use cadmium yellow as pigment was recognized in the 1840s but the lack of cadmium limited this application.[13][14][15]

Even though cadmium and its compounds may be toxic in certain forms and concentrations, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medication to treat "enlarged joints, scrofulous glands, and chilblains".[16]

...

Cadmium is used as a barrier to control neutrons in nuclear fission.[34] The pressurized water reactor designed by Westinghouse Electric Company uses an alloy consisting of 80% silver, 15% indium, and 5% cadmium.[34]-Wiki

That last passage is pretty interesting. Suppose you did have a chunk of uranium and wanted to carry it around safely. It sounds like covering it with a layer of cadmium might be a wise safety measure. And if you were ignorant of this and wanted to give someone a sample, you might cut off just the protective outer coating. Or, a tester might just happen to test the cadmium side. We will never know.

Jump to Next: The Periodic Table - chapter 19


No comments:

Post a Comment