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)

A survey of the aqueous coordination chemistry of beryllium is given. The possible use of coordination chemistry in the separation of beryllium from fission products is discussed, outlining methods for separation processes.

A comparison of methods of capital cost estimation used for nuclear fuel reprocessing plants shows that, because of the special nature and complexity of such plants, cost estimation methods for conventional chemical plants involving the use of cost factors are not applicable and will give low estimates. Cost factors which are available from other countries where reprocessing plants are installed should be used with caution since those factors apply only for the particular design philosophy used and pertain to industrial conditions which are different in this county. Capital cost estimation methods involving direct take-offs from detailed design drawings are necessary to obtain reliable estimates. The methods of estimating operating costs for nuclear reprocessing and conventional chemical plants are similar.

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.

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 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.

The isotopes of lutecium were used to measure the neutron temperatures in two collimated beans of neutrons emerging from HIFAR>

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 …

Details are given of an apparatus used to dissolve irradiated ceramic, metallic, and carbide fuel specimens, to dilute the dissolver solutions accurate to a known volume, and to take aliquots with a specially adapted automatic burette. Procedures for its use are given.

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.

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 …

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 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.

A radioisotope method has been used to measure the flow in the light water circuit of HIFAR. A mean value of 756 pounds/sec was obtained which is in fair agreement with conventional Dall tube method. Attempts to measure the flow through individual cooling towers were not entirely successful, but some useful information was 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 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.

Stable solutions of basic beryllium nitrate can be formed with beryllium concentrations up to 9M, and an NO3/Be mole ratio as low as 1:1. The efficiency of basic beryllium nitrate as an agent for salting out uranium into a tributylphosphate/kerosene solvent has been compared with that of other salts. It appears possible to separate uranium and thorium from beryllium and fission products using a modified Thorex process in which beryllium nitrate replaces aluminum nitrate.

Methods are described for the determination of traces of Be, Th, and U in concentrated sulfuric-phosphoric acid mixtures. When the Be concentration is sufficiently high, the chrome azurol S spectrophotometric method may be applied directly, and a small correction made for phosphate interference. At lower concentrations Be should be first separated by an acetylacetone extraction. Th must be separated from sulfate and phosphate before the thoronol spectrophotometric method can be used. This is achieved by precipitating Th as the fluoride, using Y carrier. U may be determined spectrophotometrically with arsonazo after separating Be, Th, suIfate, phosphate, and other impurities by anion-exchange from hydrochloric acid solution. In an alternative procedure, U is reduced to the tetravalent state and precipitated with Th as the fluoride, again using Y carrier. The determination is then completed by a-c polarography.

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 …

The concept of a dispersion fuel element is discussed with particular reference to irradiation damage. The application of this concept to the A.A.E.C. H.T.G.C. reactor system is outlined and the limitations imposed by irradiation damage considerations are discussed. The maximum desirable heavy metal - beryllium ratio (i.e. U+Th:Be) for the various systems under consideration should be about 1:55 for the system (U,Th)Be13 in Be, 1:13 for the system (U,Th)O2 in Be, and 1:8 for the system (U,Th)O2 in BeO. The disadvantages of keeping uranium and thorium in separate particles are discussed and it is suggested that to minimize irradiation damage effects, the fuel particles should consist of solid solutions of the uranium and thorium compounds.

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 performance of a Schultz-type texture goniometer is shown to be adversely affected by a number of experimental errors all of which result in defocusing of the diffracted beam. Those errors result from the tilting of the specimen, from lack of precision in positioning it and from its absorption coefficient. An experimental procedure is outlined which minimized these errors and results in optimum performance of the instrument.

1. X-ray and neutron diffraction studies were caried out on the crystal lattice of beryllium oxide annealed at 2000 degrees. 2. It was determined that neutron diffraction data confirms X-ray conclusions of the positions of beryllium atom positions in the crystal lattice of beryllium oxide. 3. From neutron diffraction data the values of the temperature fact B + 0.92 and the Debye characteristic temperature theta = 602 +- 13 degrees K were found.

A method is given for constructing the complete neutron spectrum for a well-moderated thermal reactor such a HIFAR, from the total effective flux, the temperature of the Maxwellian, the epithermal spectral index and the total integrated fission flux. A sample calculation is also included.