This report identifies a number of mechanisms that retard radionuclide migration, describes methods that are used to study such retardation phenomena and evaluates the extent to which this methods may be used to diagnose radionuclide migration through various types of geologic media. A qualitative, quantitative and applicable basis for ion exchange modelling in clay have provided. Caesium and strontium are taken as a reference elements, and itsKd values obtained from both batch and diffusion experiments are explained and independently predicted by the model.
The sorption of radiostrontium on hydrated titanium(IV) oxide was studied in batch equilibration experiments. The strontium uptake capacity was determined. Batch distribution coefficients were measured as function of solution pH as well as strontium and sodium concentration. The effect of electron beam irradiation on strontium sorption was also examined. The results are of significance in connection with the removal of radiostrontium traces from alkaline sodium salt-loaded wastes of reprocessing plant origin.
Coprecipitation of radium with precipitates composed of polyethylene glycol — metal(II) salts of heteropolyacids has been
described. The calcium salt of phosphomolybdic acid, precipitated in the presence of polyethylene glycol (m. wt. 1000) has
been chosen for the more detailed study of radium coprecipitation. The influence of acidity, amount of precipitate, concentration
of calcium cations and of polyethylene glycol on radium coprecipitation has been determined. On the basis of the results obtained,
suitable conditions for quantitative concentration of radium from aqueous solutions have been found. The described method
of radium concentration can be used for determination of radium in aqueous samples.
Authors:V. Balgavá, T. Nezkusilová, and Š. Palágyi
Open-cell polyurethane foam cylinders have been used for collecting radioiodine in the vent of a labelled compound producing plant. The cylinders were unimpregnated or impregnated with Alamine 336 with or without stable elemental iodine dissolved. A collection efficiency of about 90% has been obtained for impregnated foam cylinders.
Authors:J. La Rosa, W. Burnett, S. Lee, I. Levy, J. Gastaud, and P. Povinec
The development of radioanalytical methods for low level radionuclides in marine environmental samples is presented. In particular, emphasis is placed on the introduction of extraction chromatography (EC) as a tool for improving the quality of results as well as reducing the analysis time. However, the advantageous application of EC often depends on the effective use of suitable preconcentration techniques, such as co-precipitation, to reduce the amount of matrix components which accompany the analytes of interest. On-going investigations in this field relevant to the determination of environmental levels of actinides, 137Cs and 90Sr are discussed.
Authors:K. Hirose, M. Aoyama, T. Miyao, and Y. Igarashi
Plutonium concentrations in seawater of the western North Pacific observed over the period from 1985 to 1997 are reported. In the 1990's, surface 239,240Pu concentrations in the western North Pacific were relatively homogeneous (around 3 mBq/m3), although surface 239,240Pu before the 1980's showed a latitudinal distribution with highs in mid-latitudes and lows in the Equatorial region. Temporal variations of surface 239,240Pu in three different sea areas were examined. In mid-latitudes (21°–35°N), surface 239,240Pu exponentially decreased with an apparent residence time of 9.9 years, whereas in the subtropical and Equatorial areas, decrease rates of surface 239,240Pu were slower than in mid-latitudes. The vertical profiles of 239,240Pu in mid-latitudes of the western North Pacific showed a surface minimum, a subsurface maximum and decreased with increasing depth. The water column inventory of 239,240Pu at the station (27°48'N, 130°44'E) was calculated to be 113 Bq/m2.
Studies have shown that plots of the log of the distribution ratio versus pH for the distribution of uranium(VI) between non-plasticized and TBP-plasticized dibenzoylmethane-loaded polyurethane foams and dilute aqueous uranium(VI) solutions have a limiting slope of 0.6 at equilibrium pH values 4 and reach a maximum distribution constant at about pH 6.0. The results indicate that the extracted complex is a simple chelate, UO2Me2, where HMe denotes dibenzoylmethane. Plasticization of the foam with TBP has been found to significantly enhance the rate of extraction.
Authors:Sangita Pal, Suchismita Mishra, S. Satpati, G. Pandit, P. Tewari, and V. Puranik
“In-House” resin Polyacrylhydroxamic acid (PHOA) has been synthesized and utilized targeting ground water remediation; recovery
of uranium from low concentration aqueous solution e.g., mining activities related water, flooding of excavated or deplumed
areas, nuclear plant washed effluent and process generated effluents in nuclear plant during front-end as well as back-end
treatment. In the present study, treatment of field effluent containing heavy metals and radio-nuclides from contaminated
mining sites reflected preference for uranium with respect to manganese. The specific complexation between the extractant
and metal ion especially uranium provides high distribution co-efficient (Kd) for uranium (Kd,U = 1,450 mL/g from inlet of Effluent Treatment Plant (ETP) and Kd,U = 74,950 mL/g for synthetic solution) compared to high level impurity (1,000 times higher concentration) of manganese (Kd,Mn = 111 mL/g from inlet of ETP and Kd,Mn = 10,588 mL/g for synthetic solution). The “In-House” resin showed significant extractability (70–95% elution efficiency)
and indicates a possibility of selective removal/recovery of the valuable metal ions even from secondary sources. As a specialty,
resin can be regenerated and reused.