Abstract: "By a simple illustration it is pointed out that, conceivably, the real coupled character of the general magnetohydrodynamic equations may lead to much slower instability growth rates, if not stabilization, than predicted from the linearized set of equations."

The poor corrosion resistance of recent samples press-clad with 6,000 psi at 950 F is believed to have been due to the presence of a large number of stringers intersecting the surfaces of the uranium cores. A better quality metal and an improved pinch-weld will be used in the future. Machining of extrusion dies and mandrel tips by Moczik for the BMI extrusion cladding work is expected to be completed about mid-July. The first attempt to clad the internal surface of a tube by ``hot drawing`` has been completed. A plug was drawn through an aluminum billet placed in the tube and heated to 955 F. A weakly bonded cladding with a poor surface was produced. Several uranium-aluminum billets have been cast into a water-cooled steel mold as a means of varying the cooling rate of the alloy. Billets previously cast into a graphite mold are being examined by radiography in order to determine the effects of the rate of solidification on the segregation of the alloy.

An internally heated chlorinator using a bed of graphite as a resistor element in contact with molten salt was shown to be feasible. An extended run was completed in an electrolytic cell demonstrating the feasibility of continuous operation. Other studies are reported on chlorination of thorium oxycarbonate and physical metallurgy evaluations of the Th produced. (T.R.R.)

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A design study has been made of a graphite superheating reactor, a graphite moderated reactor with a heat rating of 305 Mw which produces superheated steam. It is designed for the production of plutonium and electrical power or for the production of electrical power only. The fuel elements for dual- purpose operation are U metal, while for single purpose action, they are uranium oxide. The fuel elements are cooled by a 7-pass system in which preheated water enters the bottom of the first pass and is discharged as superheated steam at the top of the seventh pass. The reactor control consists of shim control by the gas system, vertical gas-cooled control rods, vertical safety rods, and a ball safety system. Rough cost estimates indicate that the capital cost of the reactor should be comparable to other reactors of similar heat output.

Fillerwelding is a fusion welding process that provides for the automatic addition of controlled amounts of fillerwire during inert-gas-shielded tungsten-arc welding. Fillerwelding aluminum jacketed fuel elements has been successfully demonstrated and is being used on a routine basis. This manual was written to provide the necessary information to operate and maintain the fillerweld equipment.

Three groups of balloon flights carrying unshielded boron trifluoride counters were made from geomagnetic latitudes 10.1°N, 55.1°N, and 88.6°N. From the data obtained, curves of slow-neutron intensity versus atmospheric depth for depths less than 700 millibars are plotted. The mean absorption lengths for neutrons in the equilibrium portion of the atmosphere were found to be [formula]. The depths of the neutron intensity maxima were found to be [formula]. From these results and those of other investigators, the variation of the mean absorption coefficient and the depth of the neutron intensity maximum are plotted as functions of the geomagnetic latitude. A family of curves of neutron intensity versus atmospheric depth is drawn for geomagnetic latitudes at 10-degree intervals between 0° and 90°N, and from this the low-energy neutron capture per square centimeter per second by the N14(n,p) reaction in the atmosphere is calculated and plotted as a function of geomagnetic latitude. It is found that the observed neutron intensity varies by about 420% from 0° to 90°N. A value of 5.8×10(18) sec-1 is obtained for the total number of low-energy neutrons captured in the atmosphere.