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Fallout inhalation.

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Cesium Radioisotopes↗

Radionuclide mobility and bioavailability in Norwegian and Soviet soils.

A sequential extraction procedure has been applied to study the speciation of Chernobyl-derived radionuclides (137Cs and 90Sr) in soils from Norway, and from Byelorussia and the Chernobyl region in the USSR. Most 137Cs (greater than 80%) was strongly associated with soil components, whereas 90Sr was more mobile, up to 70% being found in the easily extractable fractions. The 90Sr: 137Cs ratio decreased with the distance from the reactor, reflecting the higher proportion of hot particles deposited in the regions close to the reactor, and the easily extractable fraction of 90Sr was significantly lower in the soils collected from the Chernobyl area. The distribution of stable Cs and stable Sr in the extraction fractions was similar for the various sites. Therefore, the location-specific differences in the distribution of 90Sr and, to a lesser extent, 137Cs arise because of fallout speciation rather than because of local environmental factors.

Accidents↗

Calibration of monitors used for surveillance of radioactivity in effluent water from CERN's accelerator installations.

Water released into the environment from CERN's accelerator installations may contain both long-lived (7Be, 22Na) and short-lived (11C, 13N, 24Na) gamma radioactivity. Each potential release point is equipped with an on-line monitor for short-lived radionuclides, which consists of a scintillation probe immersed in a tank filled with monitored water. Whilst calibration standards are available for long-lived radioactivity, computer simulations are the only feasible way to determine the monitor efficiency for the short-lived radionuclides. The paper describes computer simulations using the Monte Carlo code GEANT 3.21. An excellent agreement between measured and computed efficiencies was obtained for the long-lived radionuclides, validating the computer model. A calibration method is proposed for light positron emitters, which combines an experimental calibration for 7Be and correction factors obtained in the simulations.

Algorithms↗

Free water 3H concentrations in serum samples collected during 1969-1992 in Akita, Japan.

The measurements for human and environmental samples from the 1960's and 1970's are important to understand the long-term transfer of 3H from the environment to the human body. The authors have previously reported 3H concentrations in diet samples collected in Akita Prefecture during 1969-1988. Serum samples from persons living in Akita Prefecture during 1969-1992 were recently obtained. The samples were originally gathered for medical examinations and stored in freezers at -20 degrees C. Composite samples from 100 persons on average were made for analysis. The free water 3H (FWT) concentrations in those samples were determined and compared with 3H concentrations in diet samples and precipitation. The long-term variation pattern of the FWT concentrations in the serum samples was similar to patterns in the diet samples and precipitation, but the FWT concentrations in the serum samples were slightly higher than those in the latter two. A single compartment model calculation showed that the apparent mean residence time of serum FWT was 1.4 y using precipitation as an input to the compartment.

Adolescent↗

Radionuclide concentrations in surface air: direct relationship to global fallout.

By relating the average monthly hemispheric concentrations of radionuclides in the suirface air to the monthly hemispheric fallout of these nuclides, we have derived proportionility constants. For every disintegration per minutte of a radioactive nutclide per 1000 cubic meters of the suirface air in the Northern Hemisphere, 3.3 kilocuirics of that nutclide will be deposited on the surface; in the Soluthern Hemisphere, 5.0 kilocutries will deposit for every disintegration per minutte per 1000 cuibic meters. Oni the basis of thlese factors, the global deposition of radionuclides can be estimated from a relatively small numbnber of measurements of the radioactivity in the surface air.

Air Pollution, Radioactive↗