A brief review is presented on the various methods of separation available for both gaseous and liquid states, for the separation of short-lived fission products formed by binary fission of neutron irradiated uranium. The means available for gaseous state are the hot atom reaction, the hydride method and on-line mass separation. For liquid state, use can be made of precipitation, ionic or atomic exchange, solvent extraction and paper electrophoresis.
Particular reference is made to electrophoretic separation of ions produced by fission in aqueous solution of uranium. The principle of electrophoretic separation and the pro-cedures for separating the element of interest from the other fission products are outlined, with reference made to the results obtained with the method by the present authors. The elements in question are alkalines, alkaline earths, rare earths, halogens, selenium and molybdenum. A list is appended, enumerating the very short-lived nuclides separated by paper electrophoretic method.

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A direct search algorithm is applied to the optimization of fuel assembly allocation ;of BWR with particular consideration given to the nuclear model and the treatment of ;operating constraints. A simple expression is derived for evaluating the stuck rod margin, ;based on regression analysis of data obtained by three-dimensional full core analysis, and ;the expression is applied to optimization procedure.
The practical applicability of the method is confirmed through trial computations for ;the second and equilibrium cycles of a medium-sized commercial BWR, with an examina-;tion based on various initial guesses and objective functions for radial power peaking.

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Neutron moderation in an infinite homogeneous medium with constant cross sections, which is traditionally treated by Taylor series approximation methods, bears a close correspondence with the exact transcendental equation approach, as has been demonstrated by reducing the exact result to approximate forms. In this paper we give an alternative approach in which the convergence of the approximations to the exact result is derived by allowing the order of approximation to increase indefinitely. The approach is based on the fact that the usual approximations do not give a self consistent definition of the effective mass parameter. The present result can hence be considered as the slowing down counterpart of Davison's treatment of the one speed equation in the P_l approxi-mation.

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Experiments were conducted on the dynamic adsorption of tritiated water vapor, using a column packed with either silica-gel, activated alumina, or molecular sieve 5A. The column was 4 mm I.D. and 530 cm long. The runs were performed at 30°70°C. Tritiated water vapor (HTO) was loaded into the column with a concentration of 170 μμCi/ml, either in pulses of predetermined duration or continuously (breakthrough). The concentrations of H₂O and HTO at column outlet were measured. Particular interest was attached to observing the effect of differences in the pretreatment applied to the adsorbents (whether dried or saturated with water), and in the H₂O partial pressure of the carrier gas. It was found that the adsorption characteristics shown for HTO were not influenced to any appreciable extent by differences in the pretreatment applied to the adsorbents. On the other hand, adsorbent performance depended sensitively on the H₂O pressure in the carrier gas.
Adsorption models for a two-component mixture composed of H₂O and HTO were sought for describing the adsorption mechanism. For the particular case of the molecular sieve 5A, the Langmuir-type mixed adsorption model was found to give values agreeing fairly well with experiment. A model postulating chemisorption of H₂O into hydroxyl group on the adsorbent surface, to be subsequently replaced by tritium, was found suit-able for explaining the adsorbent behavior in the case of silica-gel.

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The kinetics of isothermal oxidation of UC powder were studied at oxygen partial pressures between 7.0×10^-4 and 1.1×10^-2 atm in the temperature range from 400 to 1, 400°C with use made of thermogravimetric techniques. Oxidation rates at the initial stage were observed to be linear against the reaction time for all the cases studied, suggesting surface reaction. Different activation energies were found for three regions of temperature--1.6 kcal/mol for region I (below about 800°C), 4.9 kcal/mol for region II (about 8001, 200°C) and 23.0 kcal/mol for region III (above about 1, 200°C). The rate-determining step for each region is discussed from the experimental results.

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