The Chemical World This Week RESEARCH & TECHNOLOGY
DECEMBER
2 5,
1961
CONCENTRATES
• The two neutron wheels used in Project Gnome have been recovered. One was
shipped to Lawrence Radiation Laboratory for study, the other to Los Alamos Scientific Labora tory. The wheels constitute one of the major ways that scientists could study the neutrons formed by Project Gnome ( C&EN, Dec. 18, page 23), now called a "qualified success" by the Atomic Energy Commission. Among the studies that will be made on the wheels are time-of-flight experiments, the fission process for neutrons of different energies (to get a better understanding of the difference between asymmetric and sym metric fission), and neutron capture cross-section for several elements—uranium-235 and lead, for example. Edges of the wheels were originally coated with the elements, and the wheels (one on top of the other) were rotating behind a con crete block containing a slit. The slit allowed neutrons from the blast to hit only a small part of the wheels' edges, with different energy neu trons hitting different parts. • Activation analysis can be used to detect selenium and other materials a t p.p.b· levels,
according to the 1961 International Conference on Activation Analysis held at Texas A&M. Selenium can be detected in quantities as low as 2 Χ 10"8 gram, Dr. Kenneth O. McConnel of the University of Kentucky told the conference. Detection at p.p.b. levels is helping scientists to learn how selenium acts in muscular and nutri tional processes. Analytical techniques worked out at Oak Ridge National Laboratory involve irradiation of a sample, followed by chemical separation and counting of radioactive selenium; irradiation of a sample along with known amounts of selenium (as a control) followed by direct counting is another method. Different neutron fluxes can be used with the techniques to give selenium isotopes having different half lives. The combination of a rotary specimen rack and a fast pneumatic transfer system permits p.p.b. and p.p.m. analyses using a TRIGA reactor, says J. D. Buchanan of General Dynamics' General Atomics Division. In pesticide residue analysis, for example, bromine at the 50 p.p.b. level has been determined. Samples and standards of ma terials that produce short half life products (a few seconds or minutes ) are carried on the rack in the reactor, then pneumatically transferred to a nearby multichannel analyzer. Depending on the half lives of the isotopes, count read-out is
done quickly using punched paper tape, or more slowly by a point-plotter or typewriter. • A new ceramic building material based on fly ash has been developed by Armour Research Foundation, Chicago. A typical formulation in cludes 90% fly ash and 10% ball clay. Addition of varying amounts of foaming agent and water gives foamed products weighing from 20 to 48 pounds per cubic foot. Compressive strengths range from 100 to 1300 p.s.i., say ARF's J. Scott Griffith and Joseph T. Dusilk. The product will take paint or glaze and can be cut, nailed, or glued. The ceramic is compatible with modern brick making equipment. About 10 million tons a year of fly ash is recovered from coal burning installations. Commonwealth Edison Co., spon sor of the development, is making public the rights to using fly ash. ^ General Electric scientists have produced electrical power by electrohydrodynamics
( E H D ) . Experiments at GE's missile and space vehicle department, Philadelphia, gave 1.4 milli watts at 170 volts. The EHD generator operates by forcing air through a corona discharge field. In the partially ionized air, neutral atoms push positive ions out of the corona field to a collecting grid. Smaller electrons do not move along with the gas, but are removed from the area of the corona field. An external electrical current re sults when the collecting grid is connected to the electron take-off. A small amount of power is required by the device to excite the corona dis charge unit. But once the EHD energy con verter is operating, only about 0.1 milliwatt is needed externally. Kinetic energy of the moving air is the main power source. EHD may serve as a power source for ion energy, GE says. • A 50,000-ton, nuclear-powered tanker will be built by two Italian companies under a contract with Euratom. About 60% of the cost will be met jointly by the two companies—Fiat Co. and Ansaldo Shipyards—while Euratom will put up the other 40%. During 1961, the Italian firms had contracted to design the vessel ( C&EN, July 24, page 37) as part of a $6 million research project sponsored by Euratom. During the first eight months of the new construction contract (which will run for two years), a reactor of an established type will be selected. During the second phase, Fiat will develop the reactor and Ansaldo will supervise planning of the ship. DEC.
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