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Abstract
Separation of technetium(VII) from uranium(VI) has been studied through experiments on the coprecipitation of technetium(VII) with precipitation of ammonium diuranate, and on the extraction of technetium(VII) from a 3M aqueous nitric acid solution using, as extractant, a primary amine (Primene JMT) dissolved in either chloroform or n-heptane solution. Ammonium diuranate precipitation proved to provide the most satisfactory means of separating technetium(VII) from uranium(VI) in solution. Extraction of technetium(VII) contained in nitric acid solution using Primene JMT dissolved in n-heptane solution proved to be quantitative after several cycles of the procedure and alternatively, upon raising to 5
1 the volume ratio between the organic phase containing the extractant and the aqueous phase containing technetium(VII). Stripping of technetium(VII) into 2M aqueous ammonium carbonate solution was enhanced to quantitative level by repetition of the stripping procedure, and alternatively, by adding the ammonium carbonate in a volume ratio of 51 with respect to the organic phase containing technetium(VII).
Abstract
The nuclear energy cycle requires the recycling of nuclear fuel, water, chemical reagents, and the volume reduction of radioactive liquid wastes. A fundamental technique for continuous recovery of water using a thin-film evaporator was examined. Appropriate recovery measurements were: an evaporator heat temperature of 323 K, a feed rate of 0.23 cm3s−1, a vacuum pressure of 15 mmHg (2 kPa), and impeller rotational speeds of 500–600 rpm (min−1). The concentration of trace technetium and rhenium in aqueous solutions was also studied. A decontamination factor of 105 for rhenium was obtained.
Abstract
Technetium(VII) extraction has been investigated to obtain useful information concerming the back-extraction of Tc(VII). Radioactive technetium-95m was used to determine the distribution ratio (D Tc) of95mTcO 4 – for Tc(VII) extraction using Primene JMT (RNH2) in heptane solution. An emulsion formation did not occur in the ammonium carbonate system but occurred in the sodium hydroxide solutions. The extraction mechanism has also determined by using the slope analysis method to study the relationships between logD Tc and log [RNH2], and between logD Tc and pH.
Abstract
The adsorbability of pertechnetate ion (TcO 4 – ) reached 96% for an active carbon at the 0.1 g/50 ml concentration level, increasing with diminution of acid and its salt concentrations, and depending on the type of anions present. With constant anion concentration, TcO 4 – adsorbability rose with decreasing pH in the acidic region, followed in the region around neutrality by a plateau, and in the basic region by an appreciable decline of TcO 4 – adsorbability. In the acidic region, part of once-adsorbed TcO 4 – appeared to be displaced by other anions. Reversibility was noted between the adsorption and desorption of TcO 4 – .
Abstract
To sophisticate the nuclear fuel recycling processes, the transfer percentages for Pd, Mo, Te, and Sb should be determined. Each element solution containing NaNO3 or HNO3 was fed consistently into the thin film evaporator regulated in vac and at 50 °C. The analyte percentages in the inside of the lid, in the condenser, and in the distillate were 10-1%/m2, 10-3%/m2, and 10-3% (DF = 105), respectively. The Mo percentage in the condenser was lower by a factor of 10 than those of other elements investigated. The NO3 - percentages were nearly constant despite increasing HNO3 concentrations, however, the ratios decreased with increasing NaNO3 concentrations.
Abstract
Ascending paper chromatography using Toyo No. 50 paper and n-BuOH saturated with 1.0M HNO3 as a developing solvent, was useful to examine the separation of polonium species in (H,NH4)NO3 solutions. A neutral mononuclear species (Po(OH)4) appeared in the vicinity of Rf=0.6. The Rf values of each species decreased depending on the increasing cationic tendency and polymerization of the polonium species.
Abstract
The separation of technetium(VII) from uranium(VI) has beeen studied through experiments on the coprecipitation of Tc(VII) with ammonium diuranate precipitate, and in the extraction of Tc(VII) from an aqueous hydrofluoric acid solution using a primary amine (Primene JMT) as an extractant dissolved inn-heptane. The extraction of Tc(VII) reached a quantitative level after several repetitions of the extraction procedure. Also, the stripping of Tc(VII) into 3M aqueous solution of ammonium carbonate was enhanced to a level over 99% by repeating the stripping cycles.
Abstract
Discontinuous and continuous volume phase transitions of organic polymer hydrogels, such as polyacrylamide (PAAm) and poly(N-isopropylamide) (PNIPA) gels, uponpH and temperature were studied by the positron annihilation lifetime measurement, which allows the estimation of size, intensity and size distribution of the free volume. Microscopic changes of physical and chemical interactions between gel network and solvent molecules and among conjugated solvent molecules at volume phase transitions of polyacrylamide gels were discussed.
Abstract
Positron annihilation lifetimes were measured for several polymers in the atmosphere of high pressure CO2 gas. At low CO2 pressured both 
3 andI
3 decreased due to the Langmuir-type sorption, and at higher pressures their values recovered because the Henry-type sorption takes over. The amount of sorbed CO2 and dilation of the bulk volume were measured simultaneously, and the free volume fraction was determined at each CO2 pressure. The free volume fraction became smaller (for polyimide and polycarbonate) or slightly larger (for polyethylene) with the progress of sorption. However, the size of the o-Ps hole estimated from the
3 value increased regardless of the change of the free volume fraction. It appears that o-Ps is selectively looking at larger holes or expanding the holes in which it is accommodated. For polycarbonate, which remains to be glassy even at the largest CO2 sorption attained in the experiment, the o-Ps hole size became larger than that before sorption. This implies that, even if the polymer is glassy as bulk, the sorption site is strongly prone to molecular displacement by the pressure of the penetrating Ps. Cautious consideration is evoked about directly correlating the o-Ps lifetime and intensity with the free volume in general.
Abstract
We made systematic studies of lanthanoid metallofullerenes on the following three properties using the radiochemical method: (1) the relative production yields of metallofullerene species, (2) variation of the HPLC retention time among M(III)@C82 species, and (3) the effects of the reactor irradiation on the survival yields of each metallofullerene species. The production yields of M@C82 relative to La@C82 were found to decrease as the atomic number of M became larger and as the number of atom ratio, M/C, in the carbon rod became larger. On the other hand, the production yields of M1M2@C82, relative to that of LuM@C82 were found to increase for the larger atomic number. The retention time for the M(III)@C82 species in the Buckyprep column was found to become slightly longer for the larger atomic number but it becomes abruptly larger for Gd, and Tb by about 5%. The overall effects of the reactor irradiation on the survival yields (or retention yields) of M@C82 species were found to be (19.7±2.1)%.
