Uranyl nitrate was extracted and stripped in pulsed packed columns and the values of (HTU)_OR were determined. The eynerimental conditions were as follows.
Amplitude of pulse 0.7-1.6cm
Frequency" 73-185cpm
Flow-rate 2-11m³/mm²hr
UO₂(NO₃)₂ concentration 0.01-0.22mol/l
HNO₃" 3-7" for extraction
(NH₄)₂SO₄" 0-40wt.%·····for stripping
Results:
(1) (HTU)_OR decreased with the increase of a×f, and showed a constant value when a×f>160 cm/min.
(2) (HTU)_OR were influenced by the flow ratio, but at a good pulsation, its influence became slight.
(3) In the case of extraction, (HTU)_OR varied with the concentration of salting-out agent and that of UO₂(NO₃)₂ at the inlet.
(4) In the case of stripping, (HTU)_OR as well as the yield of uranium depended greatly upon the flow-ratio and the concentration of the uranium, which was especially obvious with the yield of uranlum.
(5) When (NH₄)₂SO₄ was used for stripping, the changes in (HTU)_OR and the yield of uranium were not So great.

View full abstract

Although the fast reactor should be developed from the standpoint of fuel resources, a recent experiment on EBR-I has given rise to general discussion on its stability.
Main points to be studied are the influences on the stability of the fast reactor, of (1) the short life time of neutron, (2) the possibility of the existence of prompt positive temperature coefficient of reactivity, (3) the great power density and (4) the flow rate of coolant.
As the first step, the authors made a qualitative investigation of the stability of a fast reactor, using a simple model. The conditions on which the fast reactor keeps its stability are shown by Eqs. (12) and (13), which show that the fast reactor are less stable than other reactors, and which may be qualitatively expressed as follows.
As may easily be expected, if the sum of the prompt and delayed temperature coefficient is positive, the system is unstable, probably due to the inward bending of the fuel elements. If the prompt temperature coefficient is positive and the time constant of the delayed temperature coefficient is somewhat large, the instability may occur, because the flow rate of coolant is very low at the generation of certain power, or because the power per unit heat transfer area is very high at the certain flow rate of coolant. Even if the prompt temperature coefficient is negative, when the absolute value of the delayed temperature coefficient and its time constant are large, the instability may occur just the same.
Tendency to instability is inherent not only with EBR-I but with the fast reactor. Such instability, however, arises on extremely abnormal conditions. Now that this has been made clear, it would be possible to throw some light on the problem.
The experiment on EBR-I, in which the core partially melt when the coolant flow rate was zero, shows that for some time from the start of the experiment, the reactor is in a condition not satisfying Eq. (12·1) or (13) and for a short time before the melting occurs, Eq. (12·2) is not satisfied.
The frequency response of EBR-I was also studied.

View full abstract

Bursting of gas bubbles was experimentally studied, using the liquids listed in Table 1. Large drops were caught on a slide coated with a mixture of vaseline and light mineral oil, and the diameters of the drops were measured through a microscope.
The relation between the diameter of the gas bubble and the height which the drops entrained above the gas-liquid interface is shown in Figs. 3, 4 and 5, and the relation between the diameter of the gas bubble and the diameter of the drops is shown in Fig. 6. The velocity of the rising drops was calculated from Eq. (3).
In the next stage, a general theoretical formula was derived for the case in which several drops were formed from a single bubble:
where, N is the number of drops. Comparison of the theoretical values of the velocity of drops with the experimental data shown in Fig. 9 may verify the adequacy of the above equation, except for the case of liquids with high viscosity.
A natural circulation type evaporator for radioactive liquid waste disposal was constructed, and overall decontamination factor was obtained. The factor ranged over 10⁵ to 10⁷ for vapor mass velocities of 200-3, 000 kg/mm²hr as shown in Fig. 12.

View full abstract

Pulsed flow was investigated in a packed column, a perforated column and a spray column for the extraction of the system of benzene-acetic acid-water. Performance data were obtained for the extraction characteristics of and flow properties with the columns.
The results obtained may be summarized as follows:
(1) The effects of pulsation on the over-all capacity coefficient were:
For a packed column:
For a perforated-plate column:
For a spray column:
(2) The effects of pulsatio on the characteristic velocity defined by Pratt are correlated for the range of nominal packing size d_p>2.42(σ/Δρ·g)^0.5 as follows:
Values of the characteristic velocities in the pulsed perforated column and the normal packed column, calculated from Pratt's equations, were somewhat larger than the observed values in the present work.
(3) No difference was observed between the pulsed packed column and the pulsed perforated column, as to the extraction characteristics of and flow properties with them.

View full abstract