An IBM 1620 program is described that calculates the Bragg angles for cubic, hexagonal, and tetragonal crystal systems for use with powder x-ray diffraction techniques. Allowance is made for absent reflections in the case of face- and body-centered cubic and close-packed hexagonal materials.

An I.B.M. 1620 programme is described which calculates refined lattice parameters from X-ray diffraction data according to Hess' Method. The programme may be used for cubic, hexagonal, and tetragonal systems and three systematic error functions are included. The output includes the refined parameters their stand errors, and the misfit of the data at each experimental point.

Modifications to the A.A.E.C.'s Siemens Diffractometer are described which enable precision lattice parameter determinations on single crystals. Analysis of the errors and consideration of results suggest that accuracies of about 1--2 parts in 10/sup 5/ are obtained on small beryllium oxide crystals. Details of alignment and measurement procedure are included.

This manual is intended to give operating and maintenance information for the range of counting equipment in use by the A.A.E.C. at Lucas Heights, designation of Scaler Type 2A. This equipment has been designed in the General Physics Section of the A.A.E.C. General Nucleonics Division. The equipment was built by an Australian manufacturer (Siemens Nucleonics).

A method is described for the computation of the energy dependence of the neutron flux and slowing down density in a bare reactor to form the basis of a 7090 Fortran computer program for survey studies of power reactors. Allowance is made for resonance absorption and resonance fission, neutron thermalisation, fast neutron reactions including (n, 2n) and (n, n), and anisotropic elastic scattering.

Data relating to the binary and ternary systems involving beryllium oxide are presented . The survey deals with all available literature up to December 1962.

Formulas are developed for the angle between any two vectors lying in a plane through the origin of reciprocal space. The application of these formulas for computing the counter and crystal angles for the collection of data with a counter-- diffractometer in the equatorial plane is developed, and a suitable computer program, written in FORTRAN without format suitable for an IBM 1620 computer, is described.

This note describes a simple cryostatic device, which, by utilizing the latent heat of vaporization of liquid nitrogen, enables accurate control of temperature between ambient and - 150 degrees C. The advantages of this cryostat over other models known are simplicity of design and operation, ability to operate accurately from ambient to - 150 degrees C, economy, and large working space.

The heavy gas model using a synthetic kernel leads to coupled equations for the determination of the neutron flux in a bare reactor. The very special problem of solving analytically the defining equation for the energy dependent neutron flux in a region for which there are no source terms is considered. (auth)

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.

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 …

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.

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.

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.

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.

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.

The effects of fission fragment damage on vacuum hot pressed fuel specimens of (UTh)Be(12) dispersed in a beryllium matrix were examined by irradiation in a predominantly thermal neutron flux. Damage equivalent to that caused by a 4 x 10(19) to 11 x 10(19) fissions per cm3 (depending on specimen compositions) was achieved at temperatures between 435 degrees and 530 degrees C. All specimens increased in volume on irradiation. The increases ranged from 0.1 per cent to 5 per cent, depending on the volume fraction of fuel phase and the number of fissions per cm3. Some of the volume change -- possibly up to 0.7 percent -- was due to thermal effects alone. Release of fission gases was as high as 2 percent, in some cases and was generally higher than would be expected from recoil in specimens having an open porosity. The fractional release was greater in specimens which experienced a high volume increase. Microstructures showed no significant change on irradiation. All specimens were slightly porous before before irradiation and it is considered that the swelling of specimens was due to the growth of existing pores and that the release of fission gases was facilitated by an increase in open …

The results of unclassified experiments on the irradiation behaviour of BeO fueled with UO2 and (U,Th)O2 are summarized and discussed. The overall picture is still somewhat confused owing to the different experimental conditions used by different workers. A serious deficiency in most of the work is the failure to quote the energies of the irradiation neutrons and it is not clear whether the observed changes are due to fission fragment or fast neutron bombardment. The irradiation behaviour, in general, appears to be good up to fission doses of at least 5 x 10(20) fissions cm-3 of dispersion.