Cesium Radioisotopes Research Articles

Contamination of food in Czechoslovakia by caesium radioisotopes from the Chernobyl accident

Radionuclide concentrations in foodstuffs were measured in the laboratories of the Czechoslovak Monitoring Network, with special emphasis on the caesium radioisotopes, 137Cs and 134Cs, as the main long-term contaminants. Based on the temporal record of the observed data and on a knowledge of food consumption patterns, the committed effective dose equivalents were evaluated for three age groups (adults, children from 1 to 8 years and children of up to 1 year) for the first 3 years after the accident. For adults, the trend in monthly dose delivery was also determined. Seasonal changes in the committed dose equivalent rates are described and the contributions by the main foodstuffs, namely meat and milk, are assessed.

Excitation Functions for the Formation of some Radioisotopes of Cesium and Iodine in Proton and Deuteron Induced Nuclear Reactions on Natural Xenon

Excitation functions were measured using the 'stacked gas cell' technique for the fomation of {sup 127,129,132,134,136}Cs and {sup 124,126,130,131,133I} from natural xenon in proton induced reactions over the energy range of 9 to 43 MeV, and for {sup 127,129,132}Cs and {sup 124,126,130,131,133}I from in deuteron induced reactions over 22 to 53 MeV. Cross sections for the formation of radiocesium are much higher than those for the direct formation of radioiodine. The relative contributions of neutron, proton and {alpha}-particle emission processes in this mass region are briefly discussed. (orig.).

Foliar uptake of cesium, iodine and strontium and their transfer to the edible parts of beans, potatoes and radishes

Considerable fractions of radionuclide solutions deposited on the surface of the leaves may be transferred to the edible parts of plants. In radishes we observed a transfer of more than 40% of the applied cesium radioisotope within a few days. A rather similar uptake was found for beans and potatoes when harvested a month after application of radioactivity. As much as 60% of the applied cesium-isotope remained in (or on) the potato leaves even 8 days after application. The major part could however be washed off the leaves a few hours after application. When radishes were showered with water within 7 h after the application of activity the uptake was greatly reduced. No competitive effect of potassium chloride for the foliar uptake of cesium was found. A 10 -2 M colloidal suspension of Prussian Blue, a chelating agent for monovalent alkali metals such as potassium, cesium, or other monovalent cations, applied as droplets to the leaves one day prior to application of active cesium was found to strongly inhibit the transfer of cesium to the radish. The transfer of iodine and strontium to the edible parts was found to be negligible (or slower) as compared to cesium. In most cases no detectable amounts of these two nuclides were transfered to the edible parts of the radish after 2–5 weeks.

Total body potassium measurement--the effect of fallout from Chernobyl.

As a result of fallout from the nuclear accident at Chernobyl in April 1986, the caesium radioisotopes, 134Cs and 137Cs, have been detected in man. A minor consequence of this is that total body potassium (TBK) measurements obtained from the whole body activity of 40K, a naturally occurring radioisotope of potassium, can be overestimated because of gamma spectrum overlap between 134Cs and 40K. Whole-body activities for 134Cs and 40K were measured in 18 healthy adults (13 M, 5 F) in June/July, 1986, using a whole-body counter with NaI crystal scintillation detectors. Studies using anthropometric phantoms containing known activities of the two radionuclides, allowed the contribution of 134Cs to the '40K activity' in the human subjects to be assessed. The group mean 134Cs level was 172 Bq, resulting in an average overestimate in TBK of 2.8%. It is recommended that when TBK measurements are being undertaken and 134Cs contamination is suspected, then 134Cs levels should be measured and their effect corrected for.

The transfer of radiostrontium and radiocesium from soil to diet: models consistent with fallout analyses.

Abstract Radiocontaminants deposited on the soil in a temporally-localized contaminating event, such as a major nuclear-reactor accident, can become incorporated into vegetation and thence into the human diet, as a result of absorption from the soil by plant roots. Models are presented to describe the time-development of such dietary contamination by radio-isotopes of strontium and cesium. The characteristics of the local soil are represented in each model by parameters whose evaluation is complicated by their known strong dependence upon soil type (and hence upon geographic location). It is shown how these poorly-determined soil parameters can be specified with some confidence by taking full advantage of predictive formulae which have been developed empirically (by UNSCEAR and by others) from analyses of two decades of localized fallout data; this is achieved by using the models to predict contamination levels due to hypothetical, protracted fallout and comparing the resulting expressions with UNSCEARs predictive formulae.

Transport and Deposition of Metals in Sodium-Stainless Steel Systems, (III)

With the object of gaining an insight into cesium behavior in its relation to oxygen concentration in sodium-stainless steel systems, a deposition experiment was carried out with use made of stainless steel capsules containing 20 g of sodium and a trace amount of radioactive cesium. The capsule was vertically set to establish a steep axial temperature gradient, descending forward the bottom, and maintained during a period considered ample for the sodium oxide contained in excess of saturation to settle on the capsule bottom. The oxygen concentration in the sodium was varied by adjusting the temperature of the capsule bottom. The radial distribution of cesium across samples sectioned from different parts along the length of the capsule tube were determined on annular samples extruded from sections of the capsule after chilling for rapid solidification of the sodium. The activation energy for cesium deposition was obtained from partition coefficients—defined as the ratio of cesium concentration on the stainless steel surface and that in the bulk sodium. The resulting data on activation energy indicate that cesium radioisotope deposits in the temperature region below 440°C presumably by physical adsorption on the stainless steel surface when it has previously been exposed to high temperature sodium, and that this surface adsorption appears to be insensitive to differences in oxygen concentration in the sodium.

Uptake of radionuclides by some aquatic macrophytes of Ismailia Canal, Egypt

1. Uptake of the radionuclides Co-60, Cs-134, Sr-89 and P-32 by different aquatic plants present in Ismailia Canal was found to increase at increasing initial concentrations of the radionuclides in the water. 2. Maximum uptake was reached by most of the aquatic plants after different periods of contamination, ranging from 1 to 4 days. 3. Ceratophyllum was found to be the most favourable biological indicator for strontium radioisotopes in concentrations ranging from 0.5 to 10 µCi/1 and for contamination periods up to 16 days. 4. Elodea was found to serve as a biological indicator for either strontium or phosphorus radioisotopes for limited contamination periods of 2 to 16 days for Sr and to 2 days for P isotopes. 5. Potamogeton was also found to serve as a biological indicator for limited contamination periods for strontium, phosphorus and cesium radioisotopes: 0 to 2 days for Sr, 2 to 16 days for P. and 0 to 2 days for Cs isotopes.

BIOLOGICAL HALF-LIFE OF CAESIUM IN MAN IN ACUTE AND CHRONIC EXPOSURE.

THE biological half-life of an element in man is needed for the calculation of maximun permissible concentrations in air and water of radioisotopes of the element1. An important assumption in making such calculations is that the body content during chronic exposure may be predicted by mathematical integration with respect to time of the equation describing the retention following a single acute intake. This hypothesis has never been tested in man. The results of recent investigations here demonstrate the essential correctness of the assumption for radioisotopes of caesium.