Buckling measurements were taken with hollow natural uranium slugs in graphite-moderated lattices, in which the lattice spacing was varied from 6 3/16 to 15 inches in five steps. A 1.66" O.D. slug was used with two different core sizes, 1.11" I.D. and 0.81" I.D. The results of wet (water in the core) and dry measurements are reported. Buckling curves are given showing the effect on the buckling of coring the slug and placing water in the core. Simple three-region diffusion theory is applied to the measured lattices in an effort to correlate measurement with theory, but with only limited success.

This paper presents the results of a series of buckling measurements involving the use of enriched uranium rods (1.007% by weight U²³⁵) in light water. The effect of replacing a water reflector with one of uranyl nitrate solution of two different concentrations, 536 and 188 grams of U per liter of solution was investigated for the 0.925" rods with the 1.74 H₂O/U-volume ratio in the core. Some information was also obtained on the extrapolation length to be used in unreflected cases. The application of theory to these lattices, and others, is given in an appendix under separate title, "Buckling Calculations for One Per Cent Enriched Uranium-Water Rod Lattices."

In the last two or three years there has been a notable improvement in the knowledge and understanding of reactor lattice physics. During this interval, measurements of parameters have been improved and the methods of analysis have been greatly strengthened. It has become apparent that the classical ways for computing the lattice parameters are not sufficient. It is the purpose of this report to publish under one cover as much of the most recent information as possible.

Recently proposals for justifiable additions to the Plutonium Recycle Test Reactor Complex were presented to the Atomic Energy Commission at their request. In addition to a critical reactivity measuring facility in the fuel element storage basin, the following in-reactor loops were proposed: 1. A high pressure, H2O cooled fuel test loop. 2. A rupture loop to investigate fuel element failures. 3. One or more materials testing loops.

Nuclear safety in the dissolution of irradiated 0.95 U235 enriched fuel has been investigated. In particular, critical conditions of fuel of this enrichment in a 52-inch diameter dissolver crib were studied. Since a crib this size is not safe by geometry, dissolution procedures as well as maximum safe batch sizes were analyzed. Uranium-water lattices are normally studied in systems in which rods are uniformly dispersed in the moderator. The results of such a study for 1.34-inch diameter solid rods as well as I. and E. fuel having a 1.37-inch O.D. by a 0.48-inch I.D. have already reported.

This twenty-fifth quarterly report of the research and development activities of the Radiological Sciences Department, Hanford Atomic Products operation, as before, includes some items charged to control but included for general interest. The previous report of this series was numbered: HW-39624, October 11, 1955. Progress is reported in the following studies: a radiobiological-ecological survey of the Columbia River; the toxic effects of continuous low-level exposure to I¹³¹ in pigs; Pu metabolism in miniature pigs and rats; the tissue distribution and retention of Ru¹⁰⁶ and Cs in rats and mice; the radiosensitivity of the intestine of rats; the pulmonary absorption of radioactive particles and the pathological effects of such particles in the lungs of mice; the uptake of I¹³¹ and other fission products from the soil and from air by plants; determinations of the relative biological effectiveness for yeast cells of Po²¹⁰ alpha particles and P³² beta particles; the development of chemical and radiological monitoring methods; the separation of fission products from waste streams; and improvements in instruments for monitoring and low-level radiation counting. The status of the research programs of the department is reviewed.

Whenever fissile materials are handled in significant quantities such as in fuel element fabrication, separation processes, or in exponential and/or critical experiments a potential criticality hazard exists. The usual procedure which is followed by those persons conducting critical mass experiments is to either place the potential reactor in a heavily shielded cell or to conduct the experiments remotely in which case distance provides a measure of safety in the event of an unscheduled radiation outburst. In considering potential critically incidents, especially for the personnel not specifically engaged in critical mass studies, it is very likely that at the time of the incident neither the conditions of shielding nor distance will prevail for the personnel involved.

The fixation of aqueous radioactive wastes in a stable solid media by means of calcination has been the subject of considerable research and development effort. Several methods of doing this on a continuous basis have been devised and a few have been demonstrated to be feasible for the handling of non-radioactive or low activity simulated wastes. Currently an investigation of calcination by means of radiant-heat spray drying is being carried on by the Chemical Research Operation of the Hanford Laboratories Operation. The process consists of atomizing the liquid to be treated into the top of a cylindrical column, the walls of which are maintained at a high temperature. The resultant suspension of droplets in the water vapor formed by evaporation passes through successive zones of drying, calcination, possible chemical reaction or melting, and partial cooling as it proceeds down the tower. Separation of the resultant solids, steams, and uncondensable gas is made by conventional methods.

Thermal spikes occurring during the life of a slug in a pile cause a momentary destruction of the original configuration of atoms in the metal. This process occurs at such a rate that in a thermal neutron flux of 10(13) neutrons per square centimeter per second each atom in the metal will be subject to temperatures above the melting point of uranium every 40 minutes.

In support of the Plutonium Recycle Program at Hanford, the properties of PuO2 are being investigated. This paper reports sintering studies on PuO2 and PuO2-UO2 mixtures and solid solutions; melting studies on PuO2 and UO2; thermal expansion data to 1000 C; and irradiation data on PuO2-UO2 mixtures. The existence of a continuous series of solid solutions formed during sintering has been established for the system UO2-PuO2. A linear relation between lattice parameter and composition exists. Extensive sinterability data on the isomorphous compound UO2 and PuO2 and their intermediate compositions has been obtained. The effect on sintered density of temperature, time, and concentration for both physical additions of PuO2 and additions of UO2-PuO2 solid solutions to UO2 have been studied. Evaluation data are supported by microscopic examination and X-ray diffraction.

This report follows an investigation on how hydrolysis products of tributyl phosphate (such as dibutyl and monobutyl phosphoric acids, orthophosphoric acid and butanol) effect the tributyl phosphate process for uranium recovery.

From summary: "The methods of calibrating the 305 pile for impurities and density differences in graphite are reviewed and calibration constants are calculated theoretically."

Comparison of experimentally determined relaxation lengths to the value calculated from the concrete composition.

To forestall the oxidation of graphite in HAPO reactors, a process specification provides that the oxygen concentration in pile gas should be kept to a minimum. Close control in maintaining this limit is difficult when only periodic samples are taken because laboratory results are always obtained long after any required corrections should have been made. A continuous-type analyzer that provides immediate knowledge of the oxygen concentration eliminates these time delays.

Report regarding ongoing research and development undertaken at Hanfdord Laboratories' physics and instruments laboratory and chemical laboratory.

Report regarding ongoing research and development undertaken at Hanfdord Laboratories' physics and instruments laboratory and chemical laboratory.

Report regarding ongoing research and development undertaken at Hanfdord Laboratories' physics and instruments laboratory and chemical laboratory.

Report discussing information relative to the pyrophoricity of uranium for the purpose of reactor core fire safety. The report includes physical and chemical properties of uranium.

Report describing the Hanford Plutonium Recycle Test Reactor (PRTR), its building, safety procedures, site, operations, and analyses of its safety features.

From introduction: "This report provides background information regarding the study results presented in the first volume of this report and provides information resulting from the studies made on the gas cooled reactor concept."