This is the final report on the progress, "A Wide-Range Neutron Detector and Monitoring Instrument," ARF 1118-6. This report covers activities from May 8, 1958 to May 8, 1959. This report describes the basic design principles of a proportional counter that has been constructed whose cathode diameter increases towards one end.

The following report describes the investigations of the microwave solution and the Astron solution, to produce high current electron beams.

From abstract: "Steady temperatures and thermal stresses are determined for long hexagonal tubes having round holes for the case of uniform internal heat generation and a fluid-cooled inside surface. Thermal stresses are also determined for thick plates pierced by holes on an equilateral triangular pattern and for hexagonal tubes having a hexagonal hole with rounded inside corners. Stresses in the end regions of tubes are also investigated."

Samples containing 5 to 10 mg of uranium were extracted with hexone (methyl isobutyl ketone) and titrated coulometrically in sulphate media. Relative standard deviations of 0.45% for samples containing 5 mg and 0.56% for 10 mg were determined by precision studies.

The initial and long-term nuclear characteristics of two internally cooled heterogeneous, graphite-moderated, two-region, molten-salt reactors have been studied. These reactors have doubling times of 22.5 years and 27.5 years. Methods of decreasing the doubling times by removing the Pa233 from the core and be increasing the specific power of the reactor are described.

Soil chemistry studies have been carried on at Hanford for a number of years in support of the disposal of low and intermediate level liquid wastes to the ground. Equilibrium type experiments were carried out to investigate the mechanisms of the reactions of Sr, Cs, and rare earth ions with soils (1, 3, 4, 5). Experiments were also conducted with simulated and actual wastes in soil columns and an empirical method was developed for prediction of radionuclide breakthrough from ground disposal facilities into ground water on the basis of short, laboratory soil columns and equilibrium experiments (6,7). In this method it is assumed that the shape and position of the breakthrough curve is the same under laboratory conditions as in the larger scale field case. It is also assumed that the "column volume" or amount of soil effectively used for fission product sorption is that directly under a disposal facility without considering any spreading of waste solutions. These assumptions are known to be on the conservative side, but the degree of conservativeness is not known.

Continued process improvements in the separation plants provide an incentive for economics in waste storage costs by utilizing existing facilities to their maximum capability consistent with the radiological hazards involved. The major improvements have reduced waste volumes resulting in increased fission product concentration and energy potential. Analyses have been made to determine the effect of this change on the integrity of the existing structures.

The major portion of transfers and inventory in the Chemical Processing Department are dependent on volume measurement. Good volume measurements are therefore essential to good SS material control. Considerable attention has been given to the volume problem especially on primary transfer points. Document HW-57888 discusses the biasing effect pf temperature on manometer oil. HW- 57866 given the procedure for vessel calibration. Other undocumented correspondence has discussed recent calibrations and certain aspects of temperature considerations in the volume determinations. However, there is a need to document for future reference the consideration given temperature and provide at the same time information which covers the temperature angle on all volume methods used in the Chemical Processing Department.

The solids in Purex lww were first observed during flowsheet tests for recovery of fission products from plant wastes. Since the nature of this solid was not apparent from the flowsheet composition of lww, some work was performed to characterize this material. Although this work has been conducted over a period of about one year, it has been subordinate to the main one of testing flowsheets for fission product recovery. The solids have been observed in each of about six samples of plant lww that have been studied, and the centrifuged volume of solids has been about four percent in each case.

A study of metallurgical problems resulting from variation in grain boundaries, bonding layers, and inclusions in metals and alloys has become increasingly important over the past several years. To keep pace with and aid in these studies, several new techniques have been developed in emission and X-ray spectroscopy. In X-ray, areas as smalls as one square micron can be studied by making them targets for a focused electron beam and observing the X-rays emitted (5,2). Such an instrument would be quite helpful at Hanford, but the high original cost is prohibitive.

The calculation of shielding the thickness for plutonium is complicated by the many different energies represented in the gamma radiation emitted during decay of the plutonium isotopes. Dose rate predictions are also frequently confused by gamma from varying content of fission product impurities in the plutonium, as well as other gamma radiation induced through alpha and neutron particle absorption within the source material or its environment. After assumptions are made for these many factors the radiation data for shielding determination is still frequently inadequate because of wide variations in dose rates resulting from self-absorption. The degree if self-shielding is in turn dependent on nature of the plutonium compound, degree of compactness, weight, and over-all geometrical distribution of the source material. By preparing a variety of plutonium samples representing combinations of these varying factors, actual dose rates and gamma spectra, as obtained from them, can then be extrapolated for application to specific situations.

The NPR design calls for carbon steel to be the major constituent in the reactor coolant piping system. The piping and its associated fittings will, in all likelihood, be exposed to atmospheric weather conditions during the period of reactor construction. This type of exposure causes rusting. From experience gained during the startup of KER Loop 1 it is expected that there will be initially high NPR coolant activity levels. The high activity during the startup of KER Loop 1 was partially caused by the activation of rust that was eroded from pipe walls. Prevention of rusting on the carbon steel prior to its introduction into the coolant system would reduce the initial activity levels.

A series of critical experiments with blocks of 2% U235-enriched UF4-C25H52 has been initiated at the ORNL Critical Experiments Facility. Thus far assemblies with H:U235 atomic ratios of 195 and 294 have been built in parallelepipedal and simulated cylindrical geometries, both reflected and unreflected. From the results the minimum critical masses for reflected spheres have been determined to be 16.3 and 8.5 kg of U235 for fuel mixtures with H:U235 atomic ratios of 195 and 294, respectively. The minimum critical masses for unreflected spheres of these two fuel mixtures are 24.3 and 12.7 kg of U235, respectively.

The fire involved approximately 30 liters of isopropyl alcohol as a result of the ignition of about 16-18 liters of isopropyl alcohol and a slurry of thoria and ammonium nitrate in a 20-liter glass carboy. This material was undergoing a volume reduction by boiling in a floor-type metal hood with Plexiglas sides and 3 sliding door on the front of ordinary glass. The alcohol vapor was vents directly into the hood (Fig1.)