The trapping of methyl iodide from flowing humid air by impregnated charcoals was studied with regard to chemical reactions between methyl iodide and impregnants. Twenty-seven compounds for impregnation on activated charcoal were tested. Stannous iodide and potassium thiocyanate were found to be the most effective, as well as potassium iodide and triethylenediamine, for the removal of methyl iodide in flowing steam-air systems. The characteristics of the base material for impregnation and the surface properties of the impregnated charcoals are also discussed.

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Fundamental principles for designing the ideal field montoring network have been studied from the viewpoint of monitor detecting capability.
The detecting capability is specified by a radius of orbicular "detecting domain" such that the radioactive cloud flowing into the domain gives an exposure-rate above the alarm level to the detector; for example, 100m for a cloud-gamma detector at 2km downwind, 400m for a cloud-concentration monitor at 1km downwind, assuming a radioactive cloud that inflicts a dose of 100 rems to the thyroid of a child staying for 10hr at the point of maximum concentration.
The ideal distribution of detectors are obtained by adjoining their detecting domains so as to surround the reactors, keeping a outlying distance from the reactors, i. e., 1.8km, to retain complete capability for detecting a radioactive cloud, and to eliminate the direct gamma radiation assuming the 10⁶Ci of fission products confined in the reactor in an accident. In the neighborhood of reactors, film-dosimeters or TLD are advisable instead of the γ-monitors.
The concept of detecting domain is also applicable to the evaluation of the probability of detecting a radioactive cloud by a deficient monitoring network, composed of insufficient number of field monitors.

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In this paper, the performance characteristics of a linear channel LM-MHD induction converter operated in both constant current and constant voltage mode are obtained analytically, appling the slit channel approximation but taking account of variations in the traveling magnetic field intensity in the direction of the fluid flow according to differences in the disposition of the teeth and slots in the stators. The analytically obtained solutions were verified with the experimental converter with and without copper side bars operated in constant voltage mode at room temperature using NaK-78 as the electrically conducting working fluid. The experimental results obtained with the converter with copper side bars agreed with the analytically obtained solutions, though the plots of power output shifted toward greater values of negative slip compared with the theoretical curves, due to the additional ohmic losses in both the side walls of channel and the copper side bars, which were not taken into account in the present analysis.

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This paper describes a method of evaluating the effectiveness of cylindrical control rods for the general case where multiple control rods of various effective lengths affecting epithermal and thermal neutrons are arbitrarily distributed and partially inserted to mutually independent positions in a reflected reactor. This method is a generalization of the technique introduced by Nordheim & Scalettar (N-S method), employing the two-group, three-dimensional diffusion theory with modified application of the boundary condition imposed on the surface of control rods.
Either the multiplication constant or the prompt neutron decay constant can be designated as eigenvalue of the system. Moreover, vector-matrix notations are employed to faciliate the treatment of the problems and the subsequent derivation of the critical determinant.
The general problem based on the asymmetrical arrangement of control rods can be reduced to a number of special cases to find out the order of the critical determinant. We discuss the limitations of the modified N-S method. Finally, we perform numerical studies and compare the calculated results with experimental data based upon the pulsed neutron source method.

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Americium-241 was recovered by coprecipitation from an aqueous solution discarded after the purification of 50g of plutonium. Incidental plutonium which had leaked out from the purification processes was also recovered. The aqueous waste solution (30l) was made alkaline by adding an excess of calcium hydroxide. Plutonium and ²⁴¹Am were carried with a fresh precipitate of calcium hydroxide and separated from each other by ion exchange technique.
Approximately 30mg of ²⁴¹Am and 2g of plutonium were recovered. The yields were about 80% for both ²⁴¹Am and plutonium.
The salt solution after the recovery was converted to solid waste and discarded.

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The results are presented of a comparative study seeking an accurate and precise radiochemical method for ¹³⁷Cs determination in burnup measurements. The methods taken up are chloroplatinate-precipitation (Method I), tetraphenylborate-precipitation (Method II), tetraphenylborate-extraction (Method III), potassium hexacyanocobalt (II) ferrate (II)-substitution (Method IV) and ion-exchange (Method V).
A common sample, an aqueous solution obtained from dissolving irradiated uranium fuel and containing approximately 5μCi of ¹³⁷Cs, was analyzed by seven analysts using the five methods. A statistical analysis of the results obtained (105 values in all) show that the expected precision, at the 0.05 probability level, of a single determination in non-rehearsed trials of each method are: Method I, ±3.0%; Method II, ±5.6%; Method III, ±5.3%; Method IV, ±10.9%; Method V, ±4.2% The accuracy follows the same pattern except Method III and Method IV. The advantages and disadvantages of the five methods are discussed from the standpoint of utilization in burnup measurements.

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