The equipment described was designed for static displacement measurements with linear differential transformer transducers in applications requiring high sensitivity and low drift. The output from the circuit is display on a 10 mV f.s.d. potentiometric recorder and an a.c. back-off arrangement allows the same basic sensitivity up to 20 times full scale deflection. Weekly drift of the output is less than 0.1 mV which is equivalent to an input drift of 0.005 mV. For longer term measurements any drift due to valve aging etc. can be corrected by inbuilt self-checking facilities.

The dissolution of dense beryllia was studied in a variety of reagents. The dissolution rates were too slow to be of practical importance except those for hydrofluoric acid, sulfuric acid, and mixtures of sulfuric and phosphoric acids. The reaction with hydrofluoric acid was studied in more detail in an attempt to throw some light on the dissolution process. The initial dissolution rate appeared to be proportional to the square of the acid concentration between 0 and 20M. An apparent activation energy of 12 Kcal/mole BeO was obtained from the temperature coefficient of the dissolution.

The second partial differentials of the production cost equation are derived in a generalized and non-dimensional form in order to determine the effect on production cost of electricity from a gas-cooled nuclear power plant of departure from optimum operating conditions. Fuel element surface temperatures up to 650 degrees C, production costs up to 1d. (A)/kwh and reactor coolant temperature rises up to half the maximum surface temperature are included. The most significant parameter is the ratio of the reactor coolant temperature rise to maximum surface temperature which causes a maximum increase in production cost of 0.5 per cent, for a +- 5.0 percent change in its value.

This report summarises all the results obtained to date from a programme on the effects of neutron irradiation on the properties of beryllium metal. Results are presented on changes in density and mechanical properties in material fabricated by various routes and irradiated to fast neutron doses from 1019 nvt to 6 x 1023 nvt and at temperatures in the range 75ºC — 700ºC, Summaries of electron microscopy observations and electrical resistivity measurements, which are reported in more detail elsewhere., are also given, It is concluded that all the observed property changes can be interpreted in terms of the distribution of helium which is produced by fast neutron transmutation reactions in beryllium and that damage due to defect production is negligible for irradiation temperatures of 75ºC and above. Density changes duetoheiium bubble formation are shown to be very small but serious deterioration of mechanical properties can occur. The mechanical property changes and the distribution of helium are shown to be very dependent on material history and on the irradiation temperature. The standard Lucas Heights hot extruded material is shown to retain good mechanical properties for irradiation temperatures above 550ºC but serious loss of low temperature ductility is found to occur for …

Fast neutron irradiation affects the properties of beryllium oxide by causing displacements and by causing nuclear transmutations. This report outlines the overall aims of a programmer to investigate this problem, reviews the information from overseas laboratories, and describes the results obtained to date at Lucas Heights. Results are given of measurements of properties of beryllium oxide fabricated by various methods and irradiated to doses of up to 7 x 10(20) avt (fission neutrons) at temperatures of 75 - 700 degrees C. The properties include macroexamination, dimensions, porosity, lattice parameter and line broadening, mechanical properties, thermal conductivity, metallography, and long wavelength neutron scattering. It is shown that an anisotropic lattice growth occurs which results in crumbling of the material at high doses. Fine-grained (<3 mu) materials withstands crumbling up to much higher doses than coase-grained material. The relationship between macroscopic growth, latttice growth, and the cracking and powdering is discussed in some detail and the results used to show the reasons for apparent discrepancies in data from overseas laboratories. Information relating to the defect structure is discussed and it is suggested that interstitial clusters in the basal planes are probably the cause of the marked anisotropy in the lattice growth. The …

A method for comparison and evaluation of thermoelastic stresses is given for a range of fuel element shapes based on parameters available from the initial study of a reactor system. The shapes studied, in descending order of stress level are circular rods, concentric tubes, flat plates, and a matrix of circular holes.

The meter, based on the galvanic cell described by Hersh, was developed by the Analytical Chemistry Group of the A.A.E.C. Research Establishment to enable traces of oxygen in gases to be determined. The instrument consists of our main parts; the galvanic cell, the electrolytic cell, the flowrate indicator, and the control unit.

When beryllium is irradiated by fast neutrons, helium is produced by the (n,2n) and (n,α) transmutation reactions. Electron microscopy techniques have been used to study the nucleation and distribution of helium bubbles in several different grades of beryllium, after irradiation at temperatures in the range 75 — 700ºC. The effect of post-irradiation annealing is also reported. It is shown that for similar neutron doses and irradiation temperatures, there were wide variations in helium bubble size and distribution in specimens of beryllium fabricated by different methods. The most satisfactory material was that fabricated from Pechiney powder by direct hot extrusion followed by annealing for one hour at 800ºC and air cooling, it is suggested that the helium bubbles nucleate on second phase precipitates and that the distribution of this phase is strongly affected by fabrication and heat treatment.

The diffusion length of thermal neutrons in beryllium oxide of effective density 2.86 g cm-3 has been measured as 29.9 +- 0.8 cm. Using published experimental values for the diffusion constant of beryllium oxide, a value of [sigma] a = 9.0 +- 0.5 mb is deduced for the effective 2200m/s microscopic absorption cross-section.

The extraction of beryllium by triisooctylamine is measured over the pH range from 1 to 10, in the presence of malonic, maleic, succinic, phthalic, and salicylic acids. Values are obtained for the stability constants of the various metal-acid complexes by potentiometric titration. The degree of extraction is dependent on the abundance of the anionic complex present in the aqueous phase and this is in turn dependent on the strength of the corresponding acid and the stability of the complex. (auth).

Samples of vermiculite from Young River, W.A., and Kingaroy, Qld., have tested for cation exchange capacity using batch and column experiments. The better material, Young River vermiculite, was given more exhaustive column tests to determine the optimum particle size and to investigate its selectivity for caesium ions in the presence of higher concentrations of competing ions. At the optimum particle size of (-30+60) B.S.S. the cation exchange capacity of Young River vermiculite was approximately 70 meq/100g. With competing cations in solution caesium breakthrough occurs after a very small volume of influent has passed through the bed. It was concluded that neither of these vermiculite minerals would be suitable of medium level radioactive waste treatment.

Samples from possible zoolite bearing deposits have been tested for cation exchange capacity using batch and column experiments. The best material, Eagleton Quarry pink shale, was given more exhaustive column tests to determine the effect of mineral particle size, influent flowrate, and the presence of competing cations on caseium breakthrough. Diffusion of caesium ions through the mineral particle controls the ion exchange process. At the optimum size of (-30+36) B.S.S. the cation exchange capacity of Eagleton Quarry pink shale is approximately 60 meq/100g. With competing cations in solution the caesium breakthrough occurs after very small influent volumes have passed through the mineral bed and it was concluded that non of the minerals tested would be suitable for medium level radioactive waste treatment. A sample of clinoptilolite from Hector, California was also test for caesium selectivity.

Pressure drop and heat transfer in annular tubes have been measured. The surface of the inner tube was artificially roughened. The investigation covered a range of Reynolds numbers from 200 to 100,000. The maximum heat flux, directed from the inner tube to the fluid, was about 316 W/cm2 or 2.7 x 10(6) kcal/m(2) h. The heat transfer medium was water. The hydraulic diameter of the annular tube served as characteristic length in the dimensionless Reynolds and Nusselt number. The results of all experiments are presented in graphic form. Heat transfer and pressure drop increase with the degree of roughness and depend on the type and arrangement of the roughness elements chosen.

A method is presented for the analysis of transient temperatures in a homogeneous circular cylindrical fuel element in a coolant channel with no axial conduction and no heat loss to the channel wall. In addition, some results were obtained for mean fuel element temperatures in power transients for a simpler model, but accounting for details of the axial coolant temperature distribution in the unsteady state. (auth).

The equation for the H.T.G.C. reactor fuel costs developed previously in AAEC/TM141 has been modified and applied to "heterogenous" fuel systems. Fuel costs are reduced by 20-25 per cent in these systems relative to the "homogeneous" systems; these advantages arise from the longer life which may ben assumed for the unfueled beryllia and cheaper fabrication costs. The effects of reduced beryllia costs on fuel cycle costs are also examined.

The major long lived activity induced in irradiated Pechiney and Brush BeO specimens is due to Se-46 arising from scandium present to the extent of about 1 p.p.m. The Brush specimens showed additional activities due to Fe-59 and Co-60 and to Cr-51. The levels of Cr-51 found are considerably higher than would be expected on the basis of stated chromium impurity levels suggesting that the chromium is introduced during handling of the samples on site. Approximate values of the dose rate are included.

Details are given of a programme written in FORTRAN without format for an IBM 1620 computer, which computers structure factors for crystals of any symmetry. X-ray scattering factors are approximated to by exponential functions. Lp and temperature corrections are incorporated in the computations of the intensities of X-ray and neutron data collected by either the powder method or the equatorial plane method from single crystals.

Inhomogeneities in Brush UOX beryllium oxide observed in the powder and in cold pressed and sintered specimens have been removed by grinding the powder prior to fabrication, all grinding procedures reduced the densities obtained under standard sintering conditions, but some grain refinement was noted on sintering after short grinding periods. These effects are related to the introduction of alumina and silica impurities during ball milling. There is some indication that short grinding periods improve the strength of sintered specimens.

A method of gas measurement in the volume range 10(-4) - 10(-8)cc utilizing Töpler gas transport and Pirani-Stern hot-wire manometer principles is described. Sources of error are discussed and methods of avoiding them are given.

A programme is described for determining the neutron enhancement due to the (n,2n) reaction in a reactor moderated by beryllium. For moderation by pure beryllium the enhancement has been found to be 9.7 per cent.

The 25% Cr, 20% Ni type stainless steel has been proposed for use in the Australian High Temperature Gas Cooled Reactor in core structures, and in hot gas ducting. Thus a knowledge of the compatibility of this steel with high pressure carbon dioxide was required. Rates and mechanisms of corrosion were investigated for machined, vapour blasted, and etched pretreated samples of this steel, exposed to carbon dioxide up to 3,000 hours in the temperature range 650 degrees C at gas pressures from 3 p.s.i.g. to 280 p.s.i.g. Oxide film flaking as apparent at all temperatures investigated but was only severe for pre-ground samples at 710 degrees C and above, and for pre-vapour blasted samples at 760 degrees C and above. However, severe intergranular penetration was observed in pre-etched samples on exposure to carbon dioxide at 650 degrees C and above. Pressure of the gas appeared to have no systematic effect on the corrosion rate, at least in the temperature range investigated. The maximum useful temperature for which the steel could be used would be limited by the amount of oxide flaking permissible. In reactor gas circuits where a small amount of scale flaking could be tolerated, the steel is satisfactory …

An analysis of the behavior of the asymptotic flux on either side of a strongly absorbing grey slab in an otherwise uniform medium, with an arbitrary distribution of sources, leads to a method of accounting for the effect of the slab within the framework of the diffusion approximation. It is necessary to introduce a new parameter, the linear extrapolation distance at the surface of the slab in an anti-symmetrical neutron distribution.

The main difficulties of experiments on the influence of radiation on creep is metals are discussed. Some typical apparatuses for investigation by using natural sources, reactors, cyclotrons, etc., are described. These methods have resulted in relatively inaccurate measurements up to now. Therefore, the published results do not allow any statement of laws, but only tendencies. There is a surprising influence of charged particles on creep rate in spite of their low depth of penetration. The discussion of the results leads to the conclusion, that the temperature of the specimen, the stresses and the density of beam are very important. Two requirements are put forward if such researches are to be of technical importance and not only of theoretical interest.

Cadmium ratio measurements in the internal reflector of MOATA have been made with gold, indium, tungsten, manganese, molybdenum, and copper detectors. These measurements have been analyzed on the assumption that the neutron spectrum consists of a Maxwellian distribution to which is smoothly joined a 1/E slowing down spectrum cross sections being averaged according to the methods of Westcott. A search through recent literature suggests that the factors for gold and indium listed by Westcott are in error. If this is accepted then it appears that the measured epithermal spectrum is closely 1/E in form for neutron energies between one and six hundred eV. The corrections to be applied when foils of finite thickness are used in cadmium ratio measurements are discussed, and the spectrum derived from these measurements has been used to calculate reaction rate ratios of copper; indium and copper ; gold alloy foils. These ratios have been compared with measured values. Values of the effect resonance intergral of P:198 wire detectors have been measured and from these values an estimate has been made of the infinitely dilute resonance integral of this isotope.