Band 107, Heft 6

The morphological changes that take place during the processing and storage of uranium oxides can provide valuable information on the processing history and storage conditions of an interdicted sample. In this study microstructural changes in two uranium oxides (UO 2 and U 3 O 8 ) due to changes in the aging conditions at elevated temperatures were quantified and modeled using a response surface methodology approach. This allowed the morphological changes to be used as a signature for the aging conditions for nuclear forensic analysis. A Box-Behnken design of experiment was developed using the independent variables: temperature from 100 to 400 °C, aging times from 2 to 48 h, and partial pressure of O2(PO2)${{\rm{O}}_2}({{\rm{P}}_{{{\rm{O}}_{\rm{2}}}}})$ between ~0.0 kPa and 21.3 kPa. The design of experiment consisted of 54 samples per uranium oxide. Each aged sample was characterized using scanning electron microscopy (SEM) for image analysis. Utilizing the Morphological Analysis for Materials (MAMA) software package, particle size and shape were quantified using the acquired SEM images. Analysis of the particle attributes was completed using the Kolmogorov–Smirnov two sample test (K–S test) to determine if the particle size and shape distributions were statistically distinct. This data was then used to create response surfaces of the quantitative morphological changes based on the developed design of experiment. The U 3 O 8 samples showed no statistically quantifiable differences due to the aging conditions. However, the UO 2 samples had distinct morphological changes due to the experimental aging conditions. Specifically, the temperature factor had an increasing effect on the particle area, and a decreasing effect on particle circularity.

In this study, phosphate functionalized bacterial cellulose with micro-fibrous structure was prepared, characterized and applied for U(VI) adsorption. The successful grafting of phosphoric functional groups was proved by the FTIR spectra and EDS analysis (P~4.15 wt%), and the porous structure was confirmed by SEM and BET analyses. Furthermore, the effect of initial pH, contact time, initial concentration, and temperature were studied. The as-prepared adsorbent showed a high adsorption capacity at wide pH range (4.0–8.0) and its maximum adsorption capacity was calculated to be 50.65 mg/g. This endothermic adsorption process conformed to the pseudo second-order kinetic model and the Elovich kinetic models and the Langmuir isothermal models. According to the FTIR and XPS analysis, an adsorption mechanism was tentatively proposed, mainly due to the interaction between U(VI) and phosphoric groups.

Recent theoretical and experimental results, based on an extension of the Einstein theory of relativity, show that nuclear reactions of a new type can occur. In this framework, the feasibility of the deactivation of radionuclides is investigated. This paper reports the deactivation of nickel nitrate made of radioactive Nickel-63 in nitric acid by using ultrasounds. From the applicative point of view, it is a more realistic system then the previously considered thorium, not only because the molecule and the system are more complex but also because the problems related to the high corrosion and radioactivity have been treated at the same time, thus miming realistic situations like those of deactivation of nuclear waste.

89 Sr is being produced using yttria target via the nuclear reaction 89 Y(n,p) 89 Sr in Fast Breeder Test Reactor (FBTR), Kalpakkam. The isotope 89 Sr is a pure beta emitter with a half-life of 50.53 days which is useful mainly for bone pain palliation in patients with bone metastases. The existing method for processing the irradiated yttria target to obtain the pure 89 Sr source involves separation of the bulk yttrium target by solvent extraction using TBP-HNO 3 followed by purification of 89 Sr source by cation exchange chromatography technique using Dowex resin. The study described here involves the selective extraction and purification of 89 Sr by multi-column extraction chromatography technique using the Sr-specific crown ether, DtBuCH18C6 (CE) coated onto an XAD-7 resin matrix for superior separation and increased yield compared to single column technique. The 89 Sr source thus purified from the irradiated yttria target is free from other radionuclidic impurities produced during the target irradiation i.e. 88 Y, 65 Zn, 139,141 Ce, 154 Eu and 160 Tb.

In this research, the results of radon concentration, surface and mass exhalation rates, radium concentration, effective dose rate and the alpha index have been investigated in a number of 198 soil samples that have been collected from various residential locations of Halfa Aljadida area, Sudan. The can technique, containing CR-39 have been used. From our results, the average value of soil gas radon concentration was found to be 1.96±0.22 kBq·m −3 . The average values of surface and mass exhalation rates were 1.73±0.19 Bq·m −2 ·h −1 and 34.79±3.87 mBq·kg −1 ·h −1 , respectively. The radium concentration average value was 8.06±0.90 Bq·kg −1 . While the average value of the effective dose rate was recorded to be 54.69±6.11 mSv·y −1 . The average value of alpha index of studied samples was (4.03±0.45)×10 −2 . From the study, a good positive and linear correlation between radium concentration, surface and mass exhalation rates of soil samples were present. In addition to that, a positive and linear correlation between radium and radon concentrations was found. Finally, a comparison between the results and other findings was conducted and the results imply the fact that the area under consideration is safe as if the health hazard are mentioned.

This present study aims to obtain baseline data of environmental terrestrial radiation and to assess the corresponding health risk in the ambient environment in eastern region of Peninsular Malaysia. The measurements were taken 1 m above the soil surface using NaI [Ti] detector with a total of 2144 measured points which covered all geological formations and soil types. The measured gamma dose rates ranged from 26 nGy h −1 to 750 nGy h −1 with a mean value of 172±90 nGy h −1 . The mean gamma dose rate is three times higher than world averages of 57 nGy h −1 . The data of gamma dose rates show the reading of the gamma dose rates not fit to the normal distribution. The variations of gamma dose rates based on geological formation and soil types were investigated using the unbalanced one way ANOVA. The results indicated strong significant differences due to the different geological formations and soil types. The T-test of gamma dose rates for each pair of soil types or geological formations and their hypothesis test at 95 % confidential level were compared to shows the significant difference between each pairs. The results indicate that the gamma dose rates for all pairs of soil types were significant differed except the miscellaneous soil while the gamma dose rates of the pairs of geological formation were also significant differed except the intermediate and intrusive geological formations. Acid intrusive and intermediate intrusive geological formations has the highest mean values of 223 nGy h −1 and 278 nGy h −1 , respectively. These values are approximately four and five times the world average. Soil type (Steep land) has the highest gamma dose rate with the mean value of 215 nGy h −1 . The radiological health information which are the total annual effective dose equivalent, the collective effective dose, lifetime effective dose and the lifetime cancer risk for each person are 0.844 mSv, 3.53×10 3 man Sv y −1 , 59.10 mSv and 3.25×10 −3 , respectively. The results in eastern region of Peninsular Malaysia were comparable to different areas in Malaysia, which indicate the value reported in UNSCEAR, 2000 should be adjusted to the current status in Malaysia.

Radiations are widely used in hospitals and health services in radiotherapy and molecular imaging using x-ray and gamma radiation which considered as the most penetrating radiations and very difficult to shield. In this study, the radiation shielding properties of different zinc oxide (ZnO) concentrations of the (95-x)TeO 2 -5TiO 2 -xZnO (x=5, 10, 15, 20, 25, 30 and 40 mol%) glass system was investigated to be introduced as a new transparency effective shielding material. In order to study shielding properties, mass attenuation coefficients in the energy range of 0.015–15 MeV photon energies for the current glass system were calculated using ParShield software. Moreover, half value layer, mean free path and effective atomic number were evaluated using the obtained attenuation coefficient. The results indicated that if ZnO was added to the current glass system the mass attenuation coefficient will be decreased as well as effective atomic number values. The highest mass attenuation coefficient at all energies was found to be in TT 5 Z 5 glass sample as well as the effective atomic number value.

A novel high-dose dosimeter based on γ radiation reduction of copper ions and formation of copper metal inside polymer matrix were investigated. γ radiation induced synthesis of copper nanoparticles (CuNPs) in poly vinyl alcohol films were studied by UV-Visible Spectrophotometer, X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The optical absorption spectra showed that the Cu/PVA nanocomposite films have surface plasmon resonance (SPR) of copper nanoparticles which depending on irradiation doses. Upon γ irradiation these films turns its color from faint blue to deep reddish brown depending on metal ion concentration. The XRD pattern and FTIR spectrum confirm the formation of the CuNPs. The response of Cu/PVA nanocomposite dosimeters depends on both the irradiation doses and concentration of copper precursor. The dose range for these films was from 50 to 650 kGy, revealing its important applications for high dose dosimetry. Cu/PVA nanocomposites films exhibit good post-irradiation stability in dark and light.