Mobility Of Plutonium Research Articles

Selective Permeation of Plutonium(IV) through a Supported Liquid Membrane Containing Tri-iso-amyl Phosphate as an Ionophore

Selective ionophoric mobility of plutonium with ease of concentration upgradation from aqueous nitrate solutions was investigated. A thin flat-sheet supported liquid membrane (SLM) impregnated with tri-iso-amyl phosphate (TAP) was used. Accurel polypropylene hydrophobic microporous membrane ‘Enka’ was tested as the solid polymeric support. The source phase generally contained extremely dilute (ca. 10−6 mol/dm−3) to moderately concentrated plutonium(IV) nitrate solutions (ca. mol−3/dm−3) in about 4 mol/dm−3 HNO3. Membrane permeability and selectivity dependency on variables like nitric acid concentration in the source phase, carrier concentration, receiving phase composition, etc. were systematically evaluated. More than 90% pertraction of plutonium could be easily accomplished in single run employing a feed solution consisting of about 1 mg/dm−3 Pu and 4 mol/dm−3 HNO3, carrier concentration of 0.8 mol/dm−3 TAP/dodecane; the receiving phase was 0.5 mol/dm−3 sodium carbonate or 0.5 mol/dm−3 ascorbic acid. The selective diffusivity of plutonium(IV) was observed from various effluents originating from fuel reprocessing operations. Reusability of membrane supports was also found to be satisfactory.

Selective Permeation of Plutonium(IV) through a Supported Liquid Membrane Containing Tri-iso-amyl Phosphate as an Ionophore.

Selective ionophoric mobility of plutonium with ease of concentration upgradation from aqueous nitrate solutions was investigated. A thin flat-sheet supported liquid membrane (SLM) impregnated with tri-iso-amyl phosphate (TAP) was used. Accurel polypropylene hydrophobic microporous membrane ‘Enka’ was tested as the solid polymeric support. The source phase generally contained extremely dilute (ca. 10−6 mol/dm−3) to moderately concentrated plutonium(IV) nitrate solutions (ca. mol−3/dm−3) in about 4 mol/dm−3 HNO3. Membrane permeability and selectivity dependency on variables like nitric acid concentration in the source phase, carrier concentration, receiving phase composition, etc. were systematically evaluated. More than 90% pertraction of plutonium could be easily accomplished in single run employing a feed solution consisting of about 1 mg/dm−3 Pu and 4 mol/dm−3 HNO3, carrier concentration of 0.8 mol/dm−3 TAP/dodecane; the receiving phase was 0.5 mol/dm−3 sodium carbonate or 0.5 mol/dm−3 ascorbic acid. The selective diffusivity of plutonium(IV) was observed from various effluents originating from fuel reprocessing operations. Reusability of membrane supports was also found to be satisfactory.

Mobility of plutonium and americium through a shallow aquifer in a semiarid region

Treated liquid wastes containing traces of plutonium and americium are released into Mortandad Canyon, within the site of Los Alamos National Laboratory, NM. The wastes infiltrate a small aquifer within the canyon. Although laboratory studies have predicted that the movement of actinides in subsurface environments will be limited to less than a few meters, both plutonium and americium are detectable in monitoring wells as far as 3,390 m downgradient from the discharge. Between the first and last monitoring wells (1.8 and 3.4 km from the discharge), plutonium concentrations decreased exponentially from 1,400 to 0.55 mBq/L. Americium concentrations ranged between 94 and 1,240 mBq/L, but did not appear to vary in a systematic way with distance. Investigation of the properties of the mobile actinides indicates that the plutonium and part of the americium are tightly or irreversibly associated with colloidal material between 25 and 450 nm in size. The colloidally bound actinides are removed only gradually from the groundwater. The fraction of the americium not associated with colloids exists in a low molecular weight form (diameter, {<=} 2 nm) and appears to be a stable, anionic complex of unknown composition. The mobile forms of these actinides defeat the forces that normallymore » act to retard their movement through groundwater systems.« less

Mobile and immobile plutonium in a groundwater environment

The mobility of plutonium was measured by laboratory experiments conducted under conditions simulating the groundwater environment. The results thus obtained are discussed in comparison with those obtained with an in situ study on fallout plutonium migration. Plutonium (IV) was found in a series of laboratory experiments to have large distribution coefficients ( K d). On the other hand, the K d values of the fallout plutonium were about one-tenth as large as those of Pu (IV). This might be ascribed to either the different oxidation states or the difference in the chemical forms. Furthermore, a trace amount of mobile plutonium was confirmed to be produced even in the simulated groundwater environment. The production rate of mobile plutonium and the degree of change in chemical forms of plutonium during underground migration were found to be strongly influenced by the amount of suspended solids in the groundwater.

Plutonium transport to and deposition and immobility in Irish Sea intertidal sediments

The deposition and possible mobility of plutonium in sediments contaminated by nuclear fuel reprocessing wastes are of considerable importance in assessing the short- and long-term fate of this pollutant. Previous studies have shown that marine sediments very effectively and quickly remove plutonium1, and have suggested both immobile2 and mobile2,3 behaviour of plutonium after deposition. Here, the deposition characteristics and lack of vertical migration of plutonium isotopes in intertidal sediments of the Irish Sea, which are contaminated with radioactive wastes from the Windscale reprocessing facility, are discussed.

Plutonium Mobility in Soil and Uptake in Plants: A Review

AbstractA survey of the published literature pertaining to the movement of plutonium in soil and uptake in plants reveals that a major portion of the investigations pertain to soils developed under arid or semiarid climates. In some instances subsoil samples were used to describe plutonium adsorption characteristics and often short‐term greenhouse experiments were used to predict plant uptake. Some recent long‐term greenhouse studies indicate a substantially greater plant uptake of plutonium from a highly contaminated soil after 5 years of cropping as compared to the first year. It appears the most likely mode of plutonium entry into food chains leading to man would be that chelated with naturally occurring organic soil components. Chelation mechanisms have not been established.