Authors:G. Riise, H. Bjørnstad, H. Lien, D. Oughton, and B. Salbu
Measurements performed in 1986–1988 demonstrate that most of the radiocesium isotopes (137Cs and134Cs) deposited after the Chernobyl accident are still located in the upper soil layers (0–2 cm). The vertical migration appears to be slow, and only a small fraction of the radiocesium has been transferred into the biological cycle. Sequential extraction techniques have been utilized in order to investigate the degree of binding or association between deposited radionuclides (137Cs,134Cs and90Sr) and components in soil. The results indicate that a major fraction of the radiocesium is associated strongly with organic and mineral materials in the litter or upper soil layers: less than 10% is easily leachable. The distribution of137Cs throughout the fractions was similar to that determined for naturally occurring stable cesium (133Cs), implying that isotopic exchange had been extensive. For90Sr, the results show a relatively high leachable fraction. Therefore, present results indicate that radiocesium should be less mobile, and less available for root uptake, than90Sr in soil.
Authors:H. Bjørnstad, H. Lien, Yu-Fu Yu, and B. Salbu
Low level90Sr in environmental and biological samples is determined using a combined HDEHP solvent extraction-liquid scintillation procedure. Yttrium-90 is selectively extracted from nitric acid solution into 5% di(2-ethylhexyl) phosphoric acid (HDEHP) in toluene, and90Y in the organic phase is measured directly using an ultra low level liquid scintillation spectrometer.The working program of the Quantulus counter has been optimized. As the counting efficiency using liquid scintillation counting is high and the stripping and precipitation of Yttrium-90 oxalate is omitted, this procedure is simpler and more timesaving than traditional methods. The chemical recoveries of90Y were 85.1% for soil, 75.7% for milk and 65.3% for bone. The detection limit is 8 mBq.
Authors:Yu Yu-fu, B. Salbu, H. Bjørnstad, and H. Lien
An improvement of -energy resolution for determining low level plutonium has been investigated using combined solvent extraction-low level liquid scintillation counter. In the present work, -energy resolution of 270–290 keV for liquid scintillation spectra of236Pu and239Pu is attained. Thus the simultaneous determination of low level plutonium with -liquid scintillation spectrometry may be practized.
Authors:Z. Szeglowski, H. Bruchertseifer, V. Brudanin, G. Buklanov, O. Constantinescu, Dinh Lien, V. Domanov, L. Guseva, M. Hussonnois, G. Tikhomirowa, I. Zvara, and Yu. Oganessian
Some short-lived isotopes of Hf, Ta and W, synthesized at the U-400 cyclotron of JINR-Dubna, have been isolated using a previously elaborated fast continuous method of chemical isolation of element 104 from nuclear reaction products. The products were transported by a NaCl aerosol jet, from the irradiated targets to a separation device in which Hf, Ta and W were isolated by using three coupled ion-exchange columns.
Authors:Z. Szeglowski, H. Bruchertseifer, V. Brudanin, G. Buklanov, O. Constantinescu, Dinh Thi Lien, V. Domanov, L. Guseva, M. Hussonnois, G. Tikhomirova, I. Zvara, and Yu. Oganessian
The short-lived isotopes of W and their descendants have been isolated from the products of the bombardment of144Sm with24Mg by a fast continuous ion-exchange method, using HF solution media. The feasibility of this method for isolation of element 106 is discussed.
Authors:D. Schumann, R. Dressler, St. Taut, H. Nitsche, Z. Szeglowski, B. Kubica, L. Guseva, G. Tikhomirova, A. Yakushev, O. Constantinescu, V. Domanov, M. Constantinescu, Dinh Lien, Yu. Oganessian, V. Brudanin, I. Zvara, and H. Bruchertseifer
The title goal was achieved using a DOWEX 50Wx8 cation exchange column saturated with La(OH)3 and ammonia solution as eluent. Hf, Ta and Lu were adsorbed on this column, whereas W remained in the solution. This chemical system may be used for fast on-line separations of element 106.