A study was made on the decontamination of F.P. from irradiated UO₂ fuel by means of a sorption-desorption process using BaCl₂ bed. A very high degree of decontamination was obtained.
Irradiated UO₂ pellets were pulverized through a repeated oxidation-reduction process, and then chlorinated with CCl4 vapor at 580°C. The gas containing the vapor of the chlorides formed thereupon was passed through the BaCl₂ bed whose temperature varied along its length from 500° to 100°C. The vapor of the chlorides was sorbed on the bed. From this bed, zirconium and niobium chlorides were selectively desorbed by maintaining the bed at between 460° and 480°C in a mixed gas stream of Ar and CC14 vapor. The uranium chlorides, remaining on the bed, were then desorbed by maintaining the bed at 500°C in a mixed gas stream of Ar, Cl₂ and CCl₄ vapor. Cesium chloride accompanied the uranium chlorides in this process. Cerium and ruthenium chlorides remained undesorbed on the bed after both desorption processes. The vapor of uranium chlorides desorbed was trapped to recover the U. The γ-decontamination factor of the U recovered after 1, 2 and 3 cycles of the sorption-desorption process was of the order of 10², 10³ and 10⁴, respectively.

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An optimization problem of nuclear power system economics is formulated and solved numerically with the application of linear programming technique. The problem treated here is to determine the optimal long-range reactor strategy that minimizes the total requirement of natural uranium under a restriction imposed on the quantity of excess plutonium. The optimization model and the problem formulation as a linear programming problem are described in Part (I) accompanied by some examples of numerical solution. An analysis of various results of computation will be presented in Part (II) of the present work.

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Nitrogen is formed by the γ-radiolysis of 2, 2'-azo-bis-isobutyronitrile (AIBN) in benzene solution. The 100 eV yield of nitrogen G(N₂) is observed to be 1.4 at its assymptotic value attained above 0.02 M AIBN. This and other results are interpreted in terms of energy transfer from excited benzene to AIBN. Experiments using cyclohexene as a selective quencher of the triplet benzene were performed, based on which explained that, of the above G value of 1.4 for nitrogen formation, 0.8 can be attributed to the process via excited benzene in singlet state, and the remainder of the G value to the process via triplet state. Further experiments on γ-ray induced isomerization of stilbene in benzene containing AIBN have revealed that AIBN competes with trans-stilbene for the triplet benzene. The data obtained have been analyzed on the basis of competition kinetics, which has resulted in a value of 2.7 for the yield of the trip-let benzene.

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Enrichment of ⁶Li by means of electromigration was carried out in fused LiBr-KBr mixture of a composition of 1.54 (Li/K in chemical equivalent ratio).
The electromigration brought about by 847, 000 C of charge transported at 520°C, produced in the cathode compartment 38.4 meq. of Li salt with an abundance ratio of the isotopes (⁷Li/⁶Li) of 7.03, as compared with the initial value of 12.58. The distribution of the total amount of salt and of the salt composition in the migration tube agreed well with the results previously obtained on the enrichment of ⁷Li. It is suggested that, in veiw of the similarity in phase diagrams between UCl₄-CaCl₂ and LiBr-KBr systems, there are logical possibilities of ²³⁵U enrichment by analogous procedure.

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The prompt neutron emission probability of ²³³U, ²³⁵U and ²³⁹Pu is formulated through the convolution of two binomial distributions derived from a simple model representing the nuclear fission processes. Numerical calculations covering several hundred values of parameters characterizing the above distributions have resulted in a probability distribution in good agreement with the experimental results obtained by B.C. Diven et al.
Comparison is made between the newly obtained probability distribution and R.B. Leach-man's theoretical values as well as with Poisson's distribution, with results in favor of the present calculations. Statistical testing of curve fitting by means of the Kai-square testing technique has also be applied.
Physical considerations on the nuclear fission process substantiate the validity of the numerically obtained values for the above mentioned parameters.

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