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).

The slowing down spectra of neutrons were obtained for heavy water, light water, and mixtures of heavy water and light water. It was assumed that fission neutrons are produced uniformly throughout an infinite moderator and the only process considered was elastic scattering, spherically symmetric in the center-of-mass system. The (n,2n) reaction with the deuterium nucleus and absorption were assumed negligible. The average transfer cross section, fast diffusion coefficient, the slowing down area, and average velocity ratio were obtained for two-group calculations using the epithermal spectra. (auth).

Pechiney and Brush UOX BeO differ markedly in fabrication behaviour, only Brush UOX being readily sinterable. A comparative study of the two powders has shown few outstanding differences in powder properties. Both are of high purity but contain free and combined moisture to the extent of about 1.5 per cent. Pechiney BeO has a larger mean crystallite size (0.2 — 0.3μ) than Brush UOX (0.1 — 0.15μ) and a larger range of crystallite size, and both contain a small proportion of crystallites of size 1μ. and larger. The tap density of UOX is much lower than that of Pechiney, and its surface area is higher by a factor of two, UOX BeO can be hot—pressed or cold—pressed and sintered to high densities at temperatures of 1400º and 1500ºC respectively, which are approximately 300ºC lower than those required for Pechiney. Grain size of fabricated material increases with fabrication temperature in both grades, and at the same temperatures is larger for UOX than Pechiney. However, at comparable densities grain sizes are also comparable for the two materials, The bend strength at room temperature of hot—pressed Pechiney BeO reaches a maximum of approximately 30,000 p.s.i. when pressed at 1750ºC. Above this temperature the …

An investigation of the solvent extraction behavior of salicylato- beryllium complexes is reported. A simplified method for calculating the stability constants has been developed. The values obtained are beta /sub 1/ = 4.0 x 10/sup 12/ and beta /sub 2/ = 4 3 x 10/sup 22/ in 0.15 M sodium perchlorate. (auth)

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).

Beryllium is a favoured canning and/or moderating material in the proposed Australian High Temperature Gas Cooled Reactor. With carbon dioxide as the most likely coolant a detailed knowledge of the corrosion of beryllium in this gas is required. Two separate investigations have proceeded simultaneously. First the effect of the following variables was studied; surface preparation of the specimen, temperature (100—725ºC), pressure (0—280 p.s.i.g.), velocity, and impurity content of the gas. The influence of irradiation has not yet been studied. Autoclaves, thermobalances, and dynamic loops were used. The results were statistically analysed and kinetic data obtained. In all cases specimens with etched surfaces yielded approximately 25 — 30 per cent, greater weight gains than specimens with ground or polished surfaces. On extruded material no "breakaway" oxidation was encountered below 650ºC in commercially dry gas (< 20 p.p.m. moisture). The rate of attack was to some extent affected by the pressure of the gas. Breakaway was only observed in one series of specimens at 650ºC. In this particular case the gas pressure was 280 p.s.i.g. However, it seems that surface temperatures of beryllium cans made from extruded material should be maintained below 650ºC in a reactor system using the commercially pure carbon …

A description is given of a method suitable for the automatic solution of certain optimum design problems on a digital computer for cases where the number of constraints imposed on the design is not greater than the number of design variables. The problem is transformed to one requiring the minimization or maximization of an unconstrained function, for which a gradient method is used.

Comparison of the adsorption characteristics of the desiccants silica gel, alumina, and molecular sieves has shown that molecular sieves have by far the greatest capacity of the desiccants at the low partial pressures considered. Equilibrium data in the form of isotherms were established over the range of variables expected in the coolant circuit of a proposed Australian H.T.G.C. reactor. The mass transfer from the gas phase to molecular sieves is such that no correlation could be attempted for the adsorption zone height; the height proved to be too small.

The indirect addressing feature of the I.B.M.1620 computer has been used to overcome the difficulty of cross—referencing separately assembled subroutines within a computer programme. A relocatable assembler has been devised which permits the separate assembly and testing of such subroutines. The concept of a "next subroutine" has been introduced, and its applications to interpretive systems such as Fortran shown.

Breakaway corrosion of Be in moist CO2 can be avoided if the Be is fabricated using preoxidized powder. The powder is preoxidized by heating in dry O/sub 2/. Preoxidation of Be powder was measured as a function of temperature and time of heating in O/sub 2/. The subsequent reactions of the preoxidized powder in moist CO/sub 2/ at 700 deg C were studied and the effect of increasing amounts of added oxide was measured. A model is proposed to explain the inhibition of corrosion by added oxide. (auth)

Concentric tubular reactor fuel element geometries to give equal coolant outlet temperatures are presented. Oscillations from tube to tube in thickness and temperatures generally occur but it is possible to eliminate them by choice of the centre element. This may be a fuel rod or a non-heat—producing rod with or without a surrounding annulus of fuel. The geometries and temperatures are dependent on the voidage and on a non-dimensional parameter equivalent to a Biot number based on the channel equivalent diameter.

The high flux research reactor HIFAR contains ten tons of heavy water which acts as moderator and primary coolant. Over an eighteen months period regular microbiological examinations have been carried out on samples of heavy water taken from various parts of the circuit. The heavy water circuit provides an interesting opportunity for the study of microorganisms because of the high isotopic purity (greater than 99.6 per cent.), and the high chemical purity of the heavy water in the reactor. Furthermore, during its passage through the reactor core the water and suspended bacteria are subjected to intense irradiation, the neutron flux being approximately 10 14 neutrons cm-2 sec-1. The presence of bacteria in the heavy water circuit has been demonstrated and experimental results and methods used are discussed. Some evidence is presented to show that the ion—exchange resin bed contributes nutrients to support bacterial growth.

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.

A set of simultaneous differential equations is established to describe the temperature distribution for coolant flow in three concentric channels separated by walls of finite thermal conductivity and surrounding a cylindrical heat source. The solution of this set of differential equations is dependent on the heat source function Q(z) which must be known or specified. An assumed function Q(z) constant is taken as being a representative case and the resultant solutions are applied to several geometric arrangements. The system of three channel flow reduces to two channel flow when there is zero heat flow across the outer intermediate wall. This condition may arise if the wall is a perfect insulator, or if the flow in the third channel is zero. For the former case the temperature in the third channel is constant over its length, and in the second the stationary coolant assumes the temperature of the coolant in the middle channel. From the set of differential equations established for two channel flow, treatment similar to that used for three channel flow is adopted and the resultant solutions are applied to several geometric arrangements. Brief mention is made of single channel flow. By assuming that the heat sources is zero …

The matrix of a dilute homogeneous H.T.G.C. reactor fuel employing metallic beryllium as a moderator can be selectively dissolved by a caustic soda solution containing salicylate ion. At least 99 percent of the uranium and thorium can be recovered as insoluble solids, but in the case of irradiated material the uranium loss might be higher. Some decontamination of the resulting beryllium solution from fission products and Pa233 can also be obtained. A tentative chemical flowsheet is proposed on the basis of the results obtained.

As part of a general study of the co-ordination chemistry of beryllium, the beryllium salicylate complexes have been investigated by ion exchange procedures. The evidence indicates that a neutral 1 : 1 and an anionic 1 : 2 chelate exist in solution under appropriate conditions, and their stability constants have been determined by ion-exchange methos. The values of the stability constants were found to be [beta]1 = 4.97 x 10 (12), and [beta]2 = 2.63 x 10(22).

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 …

Alloy steels were studied to find types suitable for nuclear use in carbon dioxide-cooled reactors at temperatures in the range 400 - 600 degrees C. The corrosion of 2 1/4% Cr, 1% Mo steel in carbon dioxide was measured in the temperature range 460 degrees to 525 degrees C and the gas pressure range 0 to 225 p.s.i.g. The effect of gas velocity, specimen surface treatment, and water content of the gas were also determined. Adherent oxide scales of the Fe3O4 - Fe2O3 type were formed under semi-static conditions together with an unidentified spinel. A Cr2O3 film was never formed under any conditions. Weight gain depended mainly on temperature and varied little with gas pressure, surface treatment, or water content of the gas. The relationship between weight gain and time varied between parabolic and cubic with weight gains ranging from 1.7 ms/cm2 to 5.7 mg/cm2 after 1000 house exposure within the temperature range investigated. Estimated penetration depths after 10,000 hours ranged from 6.8 x 10(-4) to 18.5 x 10(-4) inches. In high velocity gas, that is, at 150 ft/sec, weight gains varied from 0.7 mg/cm2 at 460 degrees C to 2.0 mg/cm2 at 525 degrees C after 100 hours. No …

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 …

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 …

This program was prepared as a pilot program for a larger computer and handles symmetrical reactors with core, side reflector and end reflectors, using 10 radial and 10 axial mesh regions. The output consists of the effective multiplication constant, the two flux distributions, and the fission source distribution. The extrapolated Liebmann process is used for the inner iterations.

Uranium and thorium beryllides and their solid solutions were prepared by reaction-sintering, reaction—pressing and arc—melting of mixed metal powders. The major difficulties of preparation were the large swellings accompanying reaction without pressure and the loss of beryllium at temperatures above 1200 — 1300ºC, the reaction—pressing method suffered least from these difficulties and yielded the purest and most dense products.

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)

A self—abradory process is described for the small-scale preparation of 150 - 200 micron spheroidal particles of various UO2- ThO2 compositions. The particles can be sintered to high densities before or after dispersion in beryllium oxide. Because of the high compaction pressure used in making particles, they are strong enough to resist abrasion and crushing during mixing with beryllium oxide powder, after sintering, the particles consist of a (U, Th)02 solid solution with a small range of composition, but the overall composition does not vary from one particle to another. The types of porosity observed after sintering are consistent with the occurrence of two competitive mechanisms during spheroidisation, namely particle abrasion and particle build-up.