Band 107, Heft 1

This review describes some key accomplishments of Günter Herrmann such as the establishment of the TRIGA Mark II research reactor at Mainz University, the identification of a large number of very neutron-rich fission products by fast, automated chemical separations, the study of their nuclear structure by spectroscopy with modern detection techniques, and the measurement of fission yields. After getting the nuclear chemistry group, the target laboratory, and the mass separator group established at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, a number of large international collaborations were organized exploring the mechanism of deeply inelastic multi-nucleon transfer reactions in collisions of Xe and U ions with U targets, Ca and U ions with Cm targets, and the search for superheavy elements with chemical separations after these bombardments. After the Chernobyl accident, together with members of the Institute of Physics, a powerful laser technique, the resonance ionization mass spectometry (RIMS) was established for the ultra-trace detection of actinides and long-lived fission products in environmental samples. RIMS was also applied to determine with high precision the first ionization potentials of actinides all the way up to einsteinium. In the late 1980ies, high interest arose in results obtained in fusion-evaporation reactions between light projectiles and heavy actinide targets investigating the chemical properties of transactinide elements (Z≥104). Remarkable was the observation, that their chemical properties deviated from those of their lighter homologs in the Periodic Table because their valence electrons are increasingly influenced by relativistic effects. These chemical results could be reproduced with relativistic quantum-chemical calculations. The present review is selecting and describing examples for fast chemical separations that were successful at the TRIGA Mainz and heavy-ion reaction studies at GSI Darmstadt.

The aim of this study was to identify relevant Rf chemical species by using reversed-phase extraction chromatography with 2-thenoyltrifluoroacetone (TTA) resin as the stationary phase. Because TTA can be used to extract specific metal ions, the distribution ratios of the system enabled determination of the specific complex formation constant of Rf. We performed several experiments on chemical systems with Zr, Hf, No, and Rf, determined their adsorption coefficients, and deduced the K d values for Rf.

Measurement of activation cross sections for the 144 Sm(n,2n) 143g Sm reaction was performed by Cyclic Activation Method (CAM) around 14 MeV neutron energy. Natural samarium samples were irradiated by the neutrons produced by 3 H( 2 H,n) 4 He reaction using a neutron generator. Delayed γ ray activities produced by fast neutrons in samples were measured by a high resolution γ ray spectrometer [high-purity Germanium (HpGe) detector]. The measured cross sections are compared with the results of model calculation (STAPRE code) and evaluated data (JEFF 3.0/A).

To explore the diffusion behavior of 75 Se(IV) in Beishan granite (BsG), the influences of temperature, oxygen condition and ionic strength were investigated using the through-diffusion experimental method. The effective diffusion coefficient D e of 75 Se(IV) in BsG varied from 4.21×10 −14 m 2 /s to 3.19×10 −13 m 2 /s in our experimental conditions, increased with increasing temperature. The formation factor F f of BsG was calculated to be nearly constant in the range of temperatures investigated, suggesting that the inner structure of BsG had no significant change in the temperature range of 20–55°C. Meanwhile, the D e values of 75 Se(IV) in BsG under anaerobic condition was significantly larger than that under aerobic condition, which may be attributed to the difference in the sorption characteristics and species distribution of Se and pH values. Moreover, the diffusion of 75 Se(IV) was promoted with ionic strength increased from 0.01 M to 0.1 M, and then decreased at 0.5 M, mainly due to the combined effects of reduced double layers with increased ionic strength and increase of the solution viscosity at higher ionic strength.

Radioactive cesium, strontium and europium can be released as fission products during nuclear incidents and pose a major concern to contamination control because of their biological activity and long decay half-lives. Experiments were performed to study the kinetics and equilibrium of the adsorption of inactive Cs(I), Sr(II) and Eu(III) ions on a natural sandy soil. It was found that the adsorption of Cs(I), Sr(II) and Eu(III) had a second order reaction kinetics and generally reached equilibrium within 7 days. The adsorption equilibria of Cs(I) follows a Freundlich isotherm, while those of Sr(II) and Eu(III) follows a Langmuir isotherm. Adsorption increases with increasing pH for these cations studied at temperatures from 25 to 50°C. In general, the temperature effect on cation adsorption is small under these test conditions suggesting that the enthalpy change for adsorption is not significant. Tests of mixed Cs(I) and Sr(II) adsorption suggested that these cations likely adsorb on different sites on the surface of sandy soil. The desorption tests in NaCl and CaCl 2 solutions show that Eu(III) and Cs(I) are more tightly bound and less mobile in natural sandy soil than Sr(II) under the same test conditions. Tests of Cs(I), Sr(II) and Eu(III) in a column under a flowing condition revealed that these cations mainly adsorbed within the depth of 2 cm below the surface of sandy soil.

Multi-walled carbon nanotubes/strontium hydroxyapatite (MWCNT/SH) composite was synthesized, where CNTs were applied to improve the properties of HAP and increase the reinforcement of the composite. The composite CNTs/Sr-HAP and its precursor Sr-HAP were successfully applied in removal of Co(II) and Eu(III) ions from aqueous solutions. Sorption of Co(II) and Eu(III) onto the synthesized sorbents was investigated as a function of contact time and pH. The synthesized sorbents highly removed the studied radionuclides from their aqueous solutions with necessary time of 6 h to reach equilibrium. The maximum sorption capacity was 33.31 and 48.93 mg g −1 for Co(II) sorption onto Sr-HAP and CNTs/Sr-HAP composite at pH 4.5, while it was 115.74 and 127.11 mg g −1 for sorption of Eu(III) onto Sr-HAP and CNTs/Sr-HAP composite at pH 2.5, respectively. Desorption of Co(II) and Eu(III) from loaded samples was studied using various eluents and maximum recovery was obtained using FeCl 3 and HCl solutions. Co(II) was completely separated from Eu(III) by a ratio of 85.1 % using Cd(NO 3 ) 2 as an eluent in CNTs/Sr-HAP composite packed column.

The aim of the present work is to investigate the radiation absorption capacity of different soil samples in Turkey. For this purpose, we used a γ ray transmission geometry to measure the mass attenuation coefficients of eight soil samples collected between Bingöl city and Solhan district, Turkey at different γ-ray energies in the range of 13.94–88.04 keV. The radioactive sources utilized in the experiment were 241 Am, 109 Cd and 133 Ba. FFAST and WinXCOM programs were used to evaluate the theoretical mass attenuation coefficients values of the selected soil samples. There is a good agreement between experimental and theoretical results. Additionally, the mass attenuation coefficients values used to evaluate different radiation shielding parameters such as effective atomic number, half value layer and mean free path. The variation of shielding parameters was examined for soil composition and photon energy. The obtained results revealed that S6 soil sample is the best soil in terms of shielding effectiveness among all the collected soils due to lower values for half value layer and mean free path. The effective removal cross-section (Σ R ) of fast neutrons for the collected soils was also computed to examine neutrons shielding properties of the soil samples. It is found that the Σ R values for the soil samples are almost constant and lie within the range (0.04286–0.04949 cm −1 ).