No abstract available

[en] To measure the retention of 238Pu-bearing particulates on plant surfaces, corn plants were exposed to 238Pu deposition in the vicinity of the H-Area nuclear fuel chemical separations facility on the U.S. Department of Energy's Savannah River Plant. Following exposure, plants were removed to an area of lower 238Pu deposition rate and sampled every seven days for 28 days to determine 238Pu retention. To investigate the effects of exposure to wind and precipitation on 238Pu retention, some plants were maintained out of doors while others were maintained in a greenhouse. Plants maintained in the greenhouse showed no statistically significant reduction in 238Pu contents. Plants maintained outside showed 238Pu loss rates consistent with the 14-day retention half-times typically used in radiological assessments. The data analysis of outside plants was complicated by the occurrence of samples with nondetectable 238Pu contents

[en] The papers synthesize the results of research sponsored by DOE's Office of Health and Environmental Research on the behavior of transuranic and actinide elements in the environment. Separate abstracts have been prepared for the 21 individual papers

[en] Mathematical models for radionuclide loss from plant surfaces were used to predict the ²³⁸Pu inventories of wheat, soybeans and corn. Data on ²³⁸Pu inventories due to deposition were available from several fields near the H-Area nuclear fuel chemical separations facility on the US Department of Energy's Savannah River Site. The model was generally accurate. Eighteen of the 20 predicted inventories were within a factor of 2 of the observed mean inventories. Median predicted to observed ratios were 1.01, 1.23 and 0.75 for wheat, soybeans and corn, respectively. A multi-layered model composed of separate equations for 1-m height intervals of corn was slightly more accurate with median predicted to observed ratios of 1.17, 1.08 and 1.01 for the 0-1 m, 1-2m and >2 m layers, respectively. (author)

[en] A greenhouse study involving root vegetables (carrot, red beet, and turnips) was conducted primarily to evaluate the effect of culinary processing (light washing, scrubbing, and peeling) on the radionuclide content of the edible portions. In terms of concentration ratio of the radionuclides left in roots after peeling, the trend follows: ⁹⁰Sr>¹³⁷Cs>>²³⁴U congruent with ²³⁸U≥²³⁸Pu. The actinide contents in the roots were apparently due to surface adherence of the contaminated soil particulates as indicated by the diminution of the contents upon brushing the surface, which were further decreased by peeling the skin. Rigorous culinary processing of roots, such as scrubbing or peeling, could substantially diminish the contents of the actinides, but not of the more mobile ⁹⁰Sr and ¹³⁷Cs

[en] Concentrations of ²³⁸Pu and ²³⁹,²⁴⁰Pu were determined in bark, organic matter, and soil samples collected in the summer of 1975 from pine (Pinus taeda) and hardwood (Quercus falcata; Carya tormentosa) stands near a nuclear fuel reprocessing plant at the U.S. Energy Res. and Dev. Admin.'s Savannah River Plant near Aiken, S.C. The results indicated that tree crowns intercepted fallout Pu (Pu-bearing particles) and produced higher Pu concentrations in the organic matter and soil under tree crowns. Higher ²³⁹,²⁴⁰Pu concentrations were found under pines than under hardwoods. Plutonium concentrations in the O1 (litter, A₀₀) and O2 (organic matter, A₀) layers were higher than those in mineral soil, but most of the Pu was contained in the mineral soil. Higher contents of ²³⁹,²⁴⁰Pu were observed near the tree stems than in locations outside of the tree crowns. In pines these values were 163 and 80 nCi ²³⁹,²⁴⁰Pu/m₂, and in hardwoods, 122 and 80 nCi ²³⁹,²⁴⁰Pu/m₂, for the respective locations, from the litter to the 15-cm depth. The proportion of ²³⁸Pu contained in foliage, litter, and organic matter was greater than for ²³⁹,²⁴⁰Pu. However, the latter radionuclides had a greater proportion contained in the mineral soil. This observation is consistent with the more recent releases containing a higher percentage of ²³⁸Pu from reprocessing operation. Plutonium concentrations in the 5 to 15 cm depth indicated limited Pu mobility in soil, but ²³⁸,²⁴⁰Pu concentrations at this depth were higher near tree stems, suggesting greater mobility perhaps as a result of stem flow

[en] Variations in ²³⁸Pu and ²³⁹²⁴⁰Pu concentrations in surface soil near a nuclear-fuel reprocessing facility were attributed to distance from the point of aerial release; microtopographical heterogeneity in deposition; and sampling error, which included aliquoting and analytical errors. Distance from the point of release accounted for approximately 75% of the variation in concentrations of both nuclides, whereas sampling error accounted for less than 5% of the variation. Microtopographical heterogeneity accounted for approximately 20% of the variation in ²³⁹²⁴⁰Pu concentrations but only 5% of the variation in ²³⁸Pu concentrations. This difference may be due to different histories of deposition of the nuclides at the site. Other sources of variation, errors in the statistical models, and the implications for future sampling are discussed

[en] This research program has as its primary objective the description of the fate and behavior of radionuclides released to the environment from nuclear fuel chemical separations facilities. It can be grouped into two general modes of scientific approach: 1) controlled environment greenhouse uptake experiments and 2) field studies. Both modes utilize the uniquely contaminated soils and/or the ongoing operations of the separations facilities at the SRP. The greenhouse experiments seek to determine the long-term availabiltiy of radionuclides to agricultural plants from soils contaminated by a chemical separations facility. In these experiments we are also investigating factors which might modify availability of nuclear contaminants such as different crop species, soil amendments, and soil types. The field research focuses primarily on the environmental behavior in agricultural corps of chronic low-level releases of uranium. From the greenhouse uptake studies, any temporal effect on Pu and Cm uptake is inconclusive, with variable effects from different crop species, radionuclides, and soil treatments. in plant tissues of wheat and soybean crops grown near F-Area separations facility, root uptake is more important in contributing to U concentrations than Pu. This is in distinct contrast to the behavior of Pu in agro-ecosystems, where surficial pathways are the dominant modes of contamination, and is probably related to (1) the ubiquitous presence of naturally occurring U isotopes and (2) a greater phytoavailability of U than did wheat. Completion of corn radionuclide analysis will allow comparisons between Pu and U behavior and among wheat, soybean, and corn crops

[en] Research is being conducted in Pond B to determine the relative importances of (1) changes in particles settling rates, (2) changes in remobilization rates, and (3) the influence of the macrophytes on the annual cycle in /sup 239,240/Pu inventories. The initial research has emphasized (1) an evaluation of the importance of particle adherence to macrophytes in reducing Pu inventories in the water column and (2) measurements of particle settling rates at different times of the year. This report describes the research on measurements of particle settling rates. 3 figures, 1 table

[en] The research program has as its objectives the description of the fate and behavior of radionuclides released to the environment from nuclear fuel chemical separations facilities. The greenhouse uptake studies designed to examine factors which possibly can alter phytoavailability of radionuclides have shown only slight differences among crop species or soil treatment (lime or lime plus chelate) in Pu or Cm uptake. The temporal effect on Pu and Cm uptake, observed from a partial data set, is inconclusive, with variable effects from different crop species, radionuclides, and soil treatments. Cesium uptake shows variable response with different crop species but generally decreases with time. Broadleaf crops grown in the field hve differing Pu concentrations which appear to be associated with plant morphology, with some species exceeding those concentrations observed for wheat and soybean crops. In crops that tend to trap aerially deposited Pu, washing the leaves removed > 50% of the Pu. Uranium contamination of a wheat crop grown near the F-Area separations facility appears to be strongly affected by root uptake. This is in distinct contrast to the behavior of Pu in agro-ecosystems, where surficial pathways are the dominant modes of contamination, and is probably related to: (1) the ubiquitous presence of naturally occurring U isotopes; and (2) a greater concentration ratio for U than for Pu