Trennung trägerfreier radioaktiver Seltenerden durch Gaschromatographie ihrer Chelatkomplexe

Eine gaschromatographische Methode der Trennung von trägerfreien radioaktiven Lanthaniden wird beschrieben. Gaschromatogramme von Gemischen aus Gd-, Tb-, Dy-, Ho-, Er-, Tm-, Yb- und Lu-Chelaten des Pivaloyltrifluoracetons (PTA) wurden erhalten, wenn das Trägergas einen Überschuβ an PTA enthielt. Der mittlere Trennfaktor beträgt für die schweren Lanthaniden 1,4.     

Radionuclede Transport Through Fractured Porous Media

Abstract

A simplified model has been developed to arrive at spatial and temporal distribution of radionuclide concentration in fracture waters of granite host rock containing high level radioactive waste repository. The modelling has been carried out using two coupled one-dimensional equations, one for the fracture and the other for host rock. The source term to the model is provided using a two component exponential leaching system from the vitrified waste form stored in the repository. The processes considered are advection, radioactive decay and adsorption on the surface in the case of fracture, and diffusion, radioactive decay and adsorption in the microfissures of the medium in the case of host rock. The concentrations of various radionuclides are discussed in relation to the physico-chemical parameters of the system.     

Ein γ-Rückstreu-Dickenmeßgerät mit hoher Meßgenauigkeit

Es wird über ein γ-Rückstreu-Dickenmeßgerät berichtet, welches für Netz- und Batteriebetrieb geeignet ist. Das Gerät ist mit einem Schaltröhrenanalysator 1, 2 ausgestattet. Bei der Dimensionierung des Analysators wurde der Stabilität von Kanallage und Kanalbreite vorranigige Bedeutung zugeordnet. Es wird über die mit diesem Gerät ausgeführten Messungen bezüglich ihrer Genauigkeit berichtet.     

Absolute efficiency calibration of high-purity germanium detector in the range 120–8500 keV

This article reports the efficiency response curve of the high-purity germanium detector over the wide energy range, covering from 120 to 8500 keV. The efficiencies were measured for different counting geometries by using point radionuclide standards (mono-energetic as well as multi-gamma emitters) supplied by IAEA and the capture gamma-ray facility installed at PINSTECH nuclear reactor PARR-1. The measured efficiencies were required to fit with a suitable fitting function for interpolation within the energy range of interest. Several fitting functions were proposed in the literature covering different energy ranges. The functions giving the best fit to experimental data are presented. The work has successfully extended the response curve beyond 1500–8500 keV, which is the region where the standard calibration radionuclides are not available. The thermal neutron capture gamma-ray facility provided the collimated neutron beam, extracted from the core of the reactor and made to react with ammonium chloride target to produce the capture gamma rays for determining the efficiencies in the extended region. It was found that the capture gamma-ray provides a satisfactory solution to extend the absolute efficiency calibration in the MeV range. It was also found that the fitting function that is linear in its parameter was highly satisfactory up to 1500 keV but proved insufficient upto 8500 keV. The exponential function giving the good fit over the range has been presented. Good agreement has been found between the experimentally measured absolute efficiencies and the predicted result.     

Assessment of natural radionuclides and their radiological hazards in commercial granite produced in Xinjiang,China

ABSTRACT

The specific activities of ²²⁶Ra, ²³²Th and ⁴⁰K of 26 samples of granite produced in Xinjiang of China were measured by a high-purity germanium detector, and their radiological hazards of radium equivalent, external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index were evaluated. The results indicate that the overall average specific activities of ²²⁶Ra, ²³²Th and ⁴⁰K obtained in the investigated samples are below the world’s average granite values. The average radium equivalent is within the recommended limit of 370?Bq?kg^?1. The results obtained further show that the mean values of external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index are 0.65, 0.77, 111.7?nGy?h^?1, 0.55 mSv?y^?1, 0.89 and 0.23, respectively. These mean values established that radiological hazards are also found to be below the international recommended values. The results are compared with granite samples from other countries or China-Taiwan province. It can be noticed that the specific activity values of granite samples produced in China are lower or similar to that of other countries or China-Taiwan province, however there are higher specific activity values for ²²⁶Ra and ²³²Th in individual samples, which need to provide proper radiation monitoring before use considering the long term health effect.     

Soil depth profile of 137Cs, 210Pb and 40K in Algeria

ABSTRACT

Three soil depth profiles of ²¹⁰Pb, ¹³⁷Cs and ⁴⁰K at different areas of Algeria were studied. The soil sampling areas are near the location where the French nuclear tests took place at 1960–1966. The two depth soil profiles were collected at Ghardaia region and the third one at Reggane region. The vertical distributions of radionuclides at the two soil depth profiles from Ghardaia region are different, probably due to the different soil composition. The soil depth profile from sandy soil show uniformity in the distribution of radionuclides without a clear maximum (peak). The soil depth profile that characterised by silty sand show a clear peak at 20–50?cm depth for all studied radioactive nuclides, while the observed activities are two times higher than the corresponding values in sandy soil samples. More specifically in Ghardaia region the ²¹⁰Pb, ¹³⁷Cs, ⁴⁰K activity concentrations ranged between 27 and 50?Bq?kg^?1, 0.2 and 3?Bq?kg^?1 and 75 and 90?Bq?kg^?1 respectively in sandy soil type and between 37 and 75?Bq?kg^?1, 4 and 6?Bq?kg^?1 and 140 and 180?Bq?kg^?1 respectively in silty sand soil type. Finally, the third depth soil profile collected from Reggane site presents a completely different distribution of the studied radionuclides. The activity concentrations of ²¹⁰Pb, ¹³⁷Cs, ⁴⁰K ranged between 37 and 51?Bq?kg^?1, 0.16 and 0.39?Bq?kg^?1 and 120 and 309?Bq?kg^?1 respectively. Three peaks in the ¹³⁷Cs distribution revealed, were most probably, Chernobyl related ¹³⁷Cs accounts for the surface peak, while the deeper peaks are connected to the weapons fallout.     

Factors Controlling Natural Radionuclides Migration in Sedimentary Rock Samples,Gabal Um‐Hamd,Southwestern Sinai,Egypt

The activity concentrations of some radionuclides (²³⁸U, ²³⁴U, ²³⁰Th, ²²⁶Ra, ²³²Th, ⁴⁰K and ²³⁵U) were measured by γ‐ray spectrometry in order to study their behavior and the relation between them in Carboniferous rock samples collected from Gabal (mountain) Um‐Hamd, southwestern Sinai, Egypt. The whole samples are located in the two limbs and trough of a synclinal form structure to identify the radionuclides migration processes which have occurred in these rock samples. The average activity concentrations of ²³⁸U, ²³²Th, ²²⁶Ra, and ⁴⁰K measured in the all samples except sandy dolostone sample are higher than the worldwide average values as reported by UNSCEAR 2008. The activity ratios (²³⁴U/²³⁸U) for half of the samples are in equilibrium, while the other half samples are below unity indicates migration‐out of uranium. The hazard indices were also calculated. The variations in lithologic types and the configuration of the structural synform played its roles beside the physical and chemical properties of different radionuclides in their fractionations.     

Natural radionuclides and hazards of rock samples collected from Southeastern Nigeria

Gamma radiation from natural radionuclides in thirty eight rock samples collected from Southeastern Nigeria was measured using gamma-ray spectrometry method. The activity concentrations varied from 13.1 ± 1.6 Bq kg⁻¹ (ferrogeneisis shale) to 129 ± 38 Bq kg⁻¹ (granite) for ²²⁶Ra, 42.4 ± 4.5 Bq kg⁻¹ (siltstone) to 150 ± 23 Bq kg⁻¹ (pegmatite) for ²³²Th and 64.5 ± 6.3 Bq kg⁻¹ (ferrogeneisis shale) to 882 ± 298 Bq kg⁻¹ (granite) for ⁴⁰K. Hazard indices were used to determine the suitability of the rock samples for building in the context of radiological hazard. The results obtained for the radium equivalent activity and the external hazard index show that two of the samples, granite and pegmatite exceeded the recommended limits of 370 Bq kg⁻¹ and 1, respectively. However the results of the gamma index were below the recommended limit. The dose rates and the annual effective dose calculated ranged from 0.012 to 0.042 μGy h⁻¹ and 0.06–0.21 mSv, respectively.     

Porphyrins as Chelating Agents for Molecular Imaging in Nuclear Medicine

Porphyrin ligands, showing a significant affinity for cancer cells, also have the ability to chelate metallic radioisotopes to form potential diagnostic radiopharmaceuticals. They can be applied in single-photon emission computed tomography (SPECT) and positron emission tomography (PET) to evaluate metabolic changes in the human body for tumor diagnostics. The aim of this paper is to present a short overview of the main metallic radionuclides complexed by porphyrin ligands and used in these techniques. These chelation reactions are discussed in terms of the complexation conditions and kinetics and the complex stability.     

MXene二维无机材料在环境修复中的应用

MXenes是一类结构新颖的无机层状纳米材料,它是由几个原子层厚度的过渡金属碳化物、氮化物或碳氮化物构成,目前被广泛应用于能源、光学、催化和吸附等领域。由于其具有高亲水性、比表面积大、表面带负电和高离子交换力等特性,被作为一种优异的吸附剂材料。MXenes材料会通过静电吸引、配位螯合等相互作用去除环境中的重金属离子与放射性元素,有望成为吸附重金属离子与放射性元素的理想载体。本文介绍了MXene材料的结构与制备方法,其去除重金属离子(如铬(Cr)、汞(Hg)、铅(Pb)、镍(Ni))与放射性元素(如铀(U)、铯(Cs)、铕(Eu)、钡(Ba)、锶(Sr))的研究进展,并对其相关的吸附行为与相互作用机理进行了重点阐述。此外,还对MXene材料在该领域所面对的挑战和未来发展进行了展望。