Increasing trends of the concentrations of234U,235U and238U in rain observed during the period between April 1984 and June 1985 at Fayetteville (36°N, 94°W), Arkansas, and peak concentrations of234U and235U observed in a number of rain samples collected during the months of May and June 1985 appear to be the effects of delayed fallout from the 1982 eruption of El Chichón volcano and the 1983 fall of the nuclear-powered satellite Cosmos-1402, respectively.
Marked variations in the ratios of228Th/232Th,230Th/232Th and238U/232Th ratios were observed in rain samples collected at Fayetteville (36°N, 94°W), Arkansas, during 1980 through 1983. These variations are attributed to the fallout from the 1980 and 1982 eruptions of Mount St. Helens and El Chichón volcanoes.
The presence of excess uranium-235 was detected in many of the rain samples collected at Fayetteville (36°N, 94°W), Arkansas, during the period between April 1983 and March 1984. The experimental data indicate that the uranium-235 originated from the nuclear reactor on board the Soviet satellite Cosmos-1402, which fell over the South Atlantic Ocean on 7 February 1983.
Authors:F. Jiang, S. Lee, S. Bakhtiar, and R. Kuroda
A new procedure for the radiochemical measurements of thorium, uranium and plutonium in atmospheric samples is described. Analysis involves coprecipitation of these actinides with iron hydroxide from a 40-to 50-dm3 sample of rainwater, followed by radiochemical separation and purification procedures by the use of ion exchange chromatography (Dowex AG1×8) and solvent extraction. The new procedure enables one to determine the isotopes of thorium, uranium and plutonium, which are found in rainwater at extremely low concentrations, with a chemical yield ranging from 60 to 80%.
Authors:A. Mohagheghi, F. Ghanbari, S. Ebara, M. Enghauser, and S. Bakhtiar
The traditional method for determination, of alpha-emitting isotopes on air filters has been to process the samples by radiochemical
methods. However, this method is too slow for incidents involving radioactive materials where the determination of personnel
dose is urgent. A method is developed to directly analyze the air filters taken from personal and area air monitors. The site
knowledge is used in combination with alpha-spectral information to identify isotopes. A mathematical function is developed
to estimate the activity for each isotope. The strengths and weaknesses of the method are discussed.
Authors:Y. Lee, S. Bakhtiar, M. Akbarzadeh, and J. Lee
A procedure is presented to provide sequential determination of isotopic strontium, thorium, plutonium, uranium, and americium in a single biological sample. The method begins with digestion and dissolution of the sample. Tracers and/or carriers are added to the sample for the purpose of chemical yield monitoring. Strontium is first separated from the actinides and from most of the interfering constituents of the sample by precipitation as carbonates. Strontium isotopes are purified, and 89Sr and 90Sr are measured by gas proportional counting. Actinides are separated and purified by ion exchange chromatography, co-precipitated with neodymium fluoride, filtered, and counted by alpha-particle spectrometry.
Authors:T. Barbod, S. Bakhtiar, I. Essien, D. Sandoval, and P. Kuroda
Marked increases in the concentrations of thorium and uranium isotopes observed in rain samples collected at Fayetteville (36° N, 94° W), Arkansas, during 1983 are attributed to the fallout from the 1982 eruption of El chichón volcano in Mexico.