Electrodialysis in an ion-exchange membrane cell was shown to be technically feasible for the concentration of an azeotropic mixture of HF and water. A flowsheet is presented for recovery of anhydrous HF by distillation and electrodialysis of the azeotropic residue. In the electrodialysis step, 2.6 kwhr of energy per pound of anhydrous product was consumed, with electricity at 1¢ per kilowatt-hour, the total operating cost of the electrodialysis equipment alone, including amortization, would be 6¢ per pound of HF.

We have recently completed measurement of resonance escape probability in the BNL reactor and in several slightly-enriched uranium light water moderated lattices. In addition, WAPD has made available to us data from other slightly enriched uranium-water lattices, so that about 18 lattices in all have been done.

A method is described whereby many types of flaws lying close to the surface of a metal can be ultrasonically detected, regardless of the time duration of the interrogating pulses. Lamb waves are established in the metal between a flaw and the surface by an ultrasonic beam which impinges at the proper angle of incidence. A suitably positioned receiver transducer picks up the waves to reveal the flaw. In this method the usually troublesome surface echo is eliminated from the receiver by an acoustic barrier, making it well suited for routine and automatic testing. Results of applying the technique to several testing problems are discussed.

Neutron attenuation in the old pile shields is dependent more and more on the slowing down characteristics of the iron as the hydrogen is baked out of the masonite. For neutrons above 1 or 2 Mev, iron does a good job by inelastic scattering. However, below this energy attenuation can be done only by the gradual moderation by elastic scattering to thermal energies with subsequent capture in the iron. Since iron is heavy and thus a poor moderator, there is a good possibility that many neutrons of intermediate energy will leak out of a burned out shield. Also, iron has a large dip in its cross section at 25 Kev which might allow a large burst of neutrons at this energy to leak out. Measurements using a lucite moderator with gold foil detectors indicate a large leakage of neutrons of intermediate energy, but interpretation of these measurements is difficult. These considerations prompted an attempt to get a rough idea of the energy distribution of the leakage neutrons through pure iron using a simple qualitative theory.

It has been suggested by many workers in the power reactor field that a more efficient utilization of natural uranium may be obtained in thermal reactors if the Pu produced in a fuel cycle were used to enrich a subsequent cycle in which the irradiation-depleted-uranium would be reirradiated. The work described here was done for the purpose of evaluating the reactivity value of the Pu enrichment under the assumption that all plutonium produced is, after chemical separation, fabricated into separate fuel elements and not alloyed with recycled uranium. It has been suggested that the reactivity value of the Pu decreases with exposure to such an extent that highly burned plutonium should be discarded. We, therefore, wish to look at two of the variables affecting the limiting exposure: the reactivity value of the fuel as a function of exposure and temperature and the fraction of potential fissions which would be discarded as a function of exposure. Though the residence time of the Pu fuel before reprocessing, refabrication, and recycling depends upon the relative decrease in specific power, decrease in reactivity due to fission product build-up, the lifetime of the fuel elements before failure, and the cost of reprocessing, only the first …

Average coefficients of thermal expansion of the temperature range 25 C to approximately 425 C are reported for numerous types of graphite. The dependence of thermal expansion on crystal orientation and crystallite size and the effects of oxidation and cold test hole irradiation are discussed. An empirical relationship between thermal expansion and the initial rate of physical expansion under cold test hole irradiation is formulated.

A preliminary report discussing a diamond-drill exploration in the southern part of the Uravan District.

The meeting was opened by Leo Brewer, who spoke on a ``Self-Purifying Reactor.`` This is a reactor with theoretically designed-in separations processes, involving calculations to show that it is possible to vaporize many fission products away from fuels. The reactor would be analogous to a graphite rod impregnated with a uranium or thorium compound, vapor-coated with zirconium, and cooled by liquid metal. The fission products will vaporize when the rod gets hot enough, and will be carried out of the pile in a flow of helium. The details of what will happen to the rest of the pile at these temperatures, and of the materials of construction required to handle the situation are yet to be worked out. Remarks were heard from representatives of BMI, GE, Lockland, ANL, ORNL, KAPL, AEC and MCW on properties of uranium oxides and other refractory oxides.

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This letter transmits the data from the 189-D Hydraulics Laboratory flow test on three CG-482 rear pigtails. The tests were run with a standard B, D, Dr and F rear nozzle and rear Parker fitting over the range of flows and temperatures anticipated for early CG-558 operation. The data from the test are given. All three pigtails gave essentially identical results. For comparison the results of previous tests with present rear pigtails are also plotted.

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This report discusses a nuclear spectroscopic study of the radiations resulting from the electron capture decay of Ta-176, Ta-177, and Ta-178, analyzing data of nuclear decay schemes.

From introduction: "The work described here was part of an integrated investigation of the fundamental properties of uranium oxides done for the Mallinckrodt Chemical Works. Electrical measurements were employed to characterize the oxides produced by various processes from different starting materials. The basic objective of the program was to determine those factors which affect the sintering characteristics of uranium dioxide."

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This report is a summary of the physics design work performed on the Engineering Test Reactor. The ETR presents computational difficulties not found in other reactors because of the large number of experimental holes in the core. The physics of the ETR depends strongly upon the contents of the in-core experimental facilities. In order to properly evaluate the reactor' taking into account the experiments in the core, multi-region, two-dimensional calculations are required. These calculations require .the use of a large computer such as the Remington Rand Univac and are complex and expensive enough to warrant a five-stage program: 1. In the early stages of design, only preliminary two-dimensional calculations were performed .in order to obtain a rough idea of the general behavior of the reactor and its critical mass with tentative experiments in place. 2. A large amount of work was carried out in which the reactor was approximated as one with a uniform homogeneous core. With this model, detailed studies were carried out to investigate the feasibility and to obtain general design data on such points as the design and properties of the gray and black �control rods, the design of the beryllium reflector, gamma and neutron heating, the …

This volume continues with discussions of shielding provided for the heat exchanger building, concrete biological shield, top area and bottom area shielding, canal shielding, water shielding requirements during fuel element exchanges, and supplementary shielding requirements.

Evaluation of the conditions under which the interaction effects of two or more sub-critical quantities of enriched uranium may be safely arranged.