Pile, atomic

Maschine, /. machine engine airplane (atomic) pile, -lehre, /. engineering. 

System, n. system (atomic) pile, systematisch, a. systematic. 

Perhaps you have already recognized our nuclear reaction as a fission reaction. It is of (he type of reaction used in an atomic pile, the energy source of a nuclear... 

Atomic hydrogen spectrum, 253 Atomic number. 88 and periodic table, 89 table, inside back cover Atomic orbitals, 262. 263 Atomic pile, 120 Atomic theory, 17, 22, 28, 234 as a model, 17 chemical evidence for, 234 of John Dalton, 236 review, 34... 

Later, after von Neumann died, I saw his memoirs, and he had written a long series of discussions about putting a semiconductor near an atomic pile, producing neutrons which would excite the electrons in the semiconductor. He hoped to get very intense light out of the excited electrons, and he talked about stimulated emission. Apparently, he had sent this proposal to Edward Teller saying, Don t you think we should try this Edward Teller never bothered to answer. And so von Neumann dropped it. But he did not mention a resonant cavity for feedback, and he didn t mention coherence. He was just getting an intense light. 

The final answer came from the atomic pile. J. A. Marinsky, L. E. Glendenin, and C. D. Coryell at the Clinton Laboratories at Oak Ridge (20) obtained a mixture of fission products of uranium which contained isotopes of yttrium and the entire group of rare earths from lanthanum through europium. Using a method of ion-exchange on Amberlite resin worked out by E. R. Tompkins, J. X. Khym, and W. E. Cohn (21) they were able to obtain a mixture of praseodymium, neodymium, and element 61, and to separate the latter by fractional elution from the Amberlite column with 5 per cent ammonium citrate at pH 2.75. Neutron irradiation of neodymium also produced 61. 

The neptunium isotope first prepared by McMillan was Np239, but the atomic pile yielded larger amounts of Np287 which has a half-life of 2.25 X 10 years and a relatively low specific alpha-particle activity, only about one thousand times that of uranium. This isotope can be handled... 

Fermi s atomic pile was just a prototype. For manufacturing bomb plutonium, a plant was built at the tiny village of Hanford in Washington State. And so, drip by drip, the US war machine squeezed out its uranium-235 and plutonium, while the problem of how to build an atomic bomb was tackled by the physicists, chemists, and engineers at the Los Alamos complex in New Mexico. 

Muraour and Ertand (Ref 29) exposed several primary expls in the atomic pile Zoe at Chatellon, France. Pb azide, MF, diazo meta mtraniline perchlorate, Pb trinitroresorcinate, and tetracene were subjected to total steady-state thermal neutron fluxes up to 1013 neutrons/cm2. The y component was not given. No explns were obtained with any of the materials during irradiation. The only effect noticed was a slight color change from white to light brown in tetracene. 

After replicating the German fusion of the uranium atom in early 1939, Fermi was recruited to join the secret U.S. atomic bomb project, the Manhattan Project. He initially worked at the project s metallurgical laboratory at the University of Chicago, where he was chief designer of an atomic pile that achieved a sustained nuclear reaction on December 2, 1942. Throughout the war he worked on reactor design and fissionable fuel production at several project facilities. 

Fig. 21.1. Uranium metal fuel from the first atomic pile.This reactor contained 40 tons of uranium oxide along with 6.2 tons of uranium metal. (ORNL News, 1-01-076.)...

That reactor consisted of alternating layers of uranium and uranium oxide with graphite (carbon) as a moderator. Cadmium control rods were used to control the concentration of neutrons in the reactor. Since the various parts of the reactor were constructed by piling materials on top of each other, the unit was at first known as an atomic pile. ... 

Most of the light radioactive nuclides which are being produced for radiochemical work are made by the action of neutrons on suitable materials in an atomic pile (p. 436). In such a reactor there is a high flux of slow and fast neutrons and also abundant y-rays. Fast neutrons cause (n,a) and (n,p), and the slow ones (n,y) reactions. As a rule the products are -emitters. In (n,y) reactions the nuclide produced is isotopic with the parent, and cannot be separated therefrom, so the latter acts as a diluent or carrier,... 

Technetium does not occur terrestrially, but has been observed in the spectra of the sun and certain stars. Perrier and Segre (1937) made the 90-day JTc by bombarding molybdenum with high-energy deuterons from a cyclotron. The isotope more useful as a tracer is the 60-day 43TC. The long-lived J Tc is obtained (Motta, Boyd and Larsen, 1947) by long irradiation of molybdenum in an atomic pile ... 

The heart of an atomic reactor or atomic pile can be a group of uranium fuel elements. These are made from natural uranium, which contains two kinds of atoms, uranium-235 which will undergo fission and uranium-238 which will not. 

An atomic pile also creates an important by-product more nuclear fuel. 

There are other methods of preparing these same isotopes of einsteinium and fermium, and one of these involves the use of the chain-reacting atomic pile which produces a high intensity of bombarding neutrons. 

G3. Goldschmidt, B., P. Regnaut, and I. Prevot Solvent Extraction of Plutonium from Uranium Irradiated in Atomic Piles, PICGfl) 9 492 (1956). 

Deuterium has proved extremely useful as a tracer in following metabolic changes in the animal body. Many experiments have been carried out on mice. It has been shown, for example, that fat may be stored in the body even at a time when the body needs it for conversion into energy. Butyric acid is rapidly consumed to produce energy, from which it appears that butter may be expected to relieve exhaustion more rapidly than other fats. Deuterium Dxide, DaO, often called heavy water is used as a moderator in atomic piles to slow down fast moving neutrons to the speed desired. Most substances either absorb neutrons or are otherwise unsuitable neither deuterium nor oxygen absorbs them. 

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