The numerical solution of the double P/sub 3/ equations in slab geometry, by a forward-elimination back-substitution process, is described and is illustrated by application to a slab self shielding problem and by comparison with the results obtained by analytical solution of the equations.

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

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.

Fuel specimens having uranium—thorium beryllides as the fissile bearing phase were irradiated at 400 to 700 ºC to burn—ups between 7 and 11a/0 uranium in a predominantly thermal flux, two specimens of massive (U;Th)Be13 exhibited good dimensional stability and low fission gas release. Dispersion specimens containing 20, 35, and 50v/o (U,Th)Be13 swelled by 3 to 18 per cent, and released up to 33 per cent, of the gaseous fission products. The results indicate that the mixed beryllide is an inherently good fuel material and lead to the conclusion that the poor irradiation stability of hot—pressed specimens may not be typical of (U,Th)Be13— Be dispersions prepared by other techniques.

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).

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)

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 …