Volume 108, Issue 6

To directly separate actinides from high level liquid waste (HLLW), a novel molecule, i. e. iso Pentyl-BTBP (6,6′-bis(5,6-bis(4-methylpentyl)-1,2,4-triazin-3-yl)-2,2′-bipyridines) was synthesized and characterized. A kind of iso Pentyl-BTBP/SiO 2 -P adsorbent was obtained by impregnating iso Pentyl-BTBP into porous silica/polymer support particles SiO 2 -P under reduced pressure. The effect of HNO 3 concentration, contact time on the adsorption of iso Pentyl-BTBP/SiO 2 -P towards 241 Am(III) and 239 Pu(IV) was studied. And the stability of iso Pentyl-BTBP/SiO 2 -P in HNO 3 medium was also evaluated. It turned out that iso Pentyl-BTBP/SiO 2 -P had much higher affinity for 241 Am(III) and 239 Pu(IV) over FP elements in 3 M HNO 3 , fast adsorption kinetics towards 239 Pu(IV), excellent stability in HNO 3 medium, and should be a very promising adsorbent for separating 239 Pu(IV) and 241 Am(III) from HLLW.

Zirconium phosphosilicate (ZPS) has been prepared by gelation route for its ion exchange applications. ZPS was characterised by X-ray diffraction technique (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), Fourier transformed Infrared Spectrometry (FTIR) and surface area analysis. K + ion exchange behaviour was studied by pH titration. The material was found to extract Pu selectively over U from different mineral acids. Pu sorption behaviour on ZPS packed column was also been carried out. The pore volume was evaluated as 0.1336 mL g −1 . The FTIR revealed the presence of –OH and PO 4 3− groups on the surface of the material, while the SEM image indicates the irregular morphology and size of the sorbent. Different isotherm model: Langmuir, Freundlich, Dubinin–Rodushkevich and Temkin were used to understand the nature of sorption, while Lagergren 1st order, Intraparticle diffusion and pseudo 2nd order kinetics were used for modelling sorption kinetics. Suitable elution method was used for quantitative stripping of plutonium from sorbent. The radiolytic stability of the sorbent was evaluated upto 1500 kGy. A comparative evaluation of the sorption process has also been carried out with that reported in literature.

The suitability of perrhenate (Re(VII)) to act as an analog for pertechnetate (Tc(VII)) was tested using solvent extraction and the carrier/tracer systems 99 Tc(VII)/ 99m Tc(VII) and 185/187 Re/ 186/188 Re(VII). Perrhenate is often used as a non-radioactive analogue of pertechnetate, but scarce data is available for the comparison of these metals for liquid-liquid extraction applications. Results show that neither Tc(VII) nor Re(VII) extraction is influenced by pH in the 2–8 range. The anion extractant also separates electrolyte anions, with increasing extraction following the order Cl −  < NO 3 −  ≪ ClO 4 − , resulting in a decreased Tc(VII) and Re(VII) extraction in presence of salt. In particular, the extraction of Re and Tc is suppressed in presence of NaCl at concentrations higher than 1 mM. While Tc extraction is larger than that of Re in absence of electrolyte, they are statistically identical in presence of enough electrolyte. Furthermore, tetraphenylphosphonium chloride (Ph 4 PCl) is a stronger extractant than iodonitrotetrazolium chloride (INT).

Potassium cobalt hexacyanoferrate(II) [K 2 CoFe(CN) 6 ] is an extremely selective ion exchanger for cesium ions. To examine the atomic level background for the selectivity a computational structural study using DFT modelling was carried out for K 2 CoFe(CN) 6 and for products where Cs has replaced K in the elemental cube cages closest to the surface. In the K-form compound the potassium ions are not in the center of the Co–Fe–CN elementary cube cages closest to the surface but locate about 140 pm from the cube center towards the surface. When cesium ions are exchanged to these potassium ions they locate much deeper from the surface, being only about 70 pm upwards from the cube center. This apparently leads to much stronger bonding of cesium compared to potassium. Once taken up into the outermost cube cages on the surface of the crystallites cesium ions are not able to penetrate further since they are much larger than the electron window between the cubes. Furthermore, they are not able to return to the solution phase either leading to a practically irreversible sorption.

Theoretical studies via nuclear reaction models have an undeniable importance and impact in terms of better understanding of reaction processes and their nature. In this study, by considering the importance of these models and the medical radionuclides, the effects of six level density models and eight alpha optical model potentials on the cross-section calculations for the production of the radionuclides 62 Cu, 67 Ga, 86 Y and 89 Zr via 59 Co(α,n) 62 Cu, 60 Ni(α,np) 62 Cu, 65 Cu(α,2n) 67 Ga, 64 Zn(α,p) 67 Ga, 85 Rb(α,3n) 86 Y, 86 Sr(α,n) 89 Zr, 87 Sr(α,2n) 89 Zr and 88 Sr(α,3n) 89 Zr reactions were investigated. Calculations for each reaction route were performed by using the TALYS v1.9 code. The most consistent model with the literature data taken from the Experimental Nuclear Reaction Database (EXFOR), was identified by using the reduced chi-squared statistics in addition to an eyeball estimation. Also, the effects of combinational use of selected models and potentials were investigated by comparing the calculational results with the experimental data.

Copper-67 ( 67 Cu), a feasible radionuclide for diagnosis and radiotherapy, is commercially generated from a bulk zinc (Zn) target using the 68 Zn(p, 2p) 67 Cu and 68 Zn(γ, p) 67 Cu nuclear reactions. Because it uses a large amount of zinc, the separation is complex – requiring a combination of three ion exchange columns – and is time-consuming (about 1 day). We developed a quick and easy separation method referred to as “double coprecipitation” using H 2 S gas and silver nitrate as coprecipitation agents in place of ion exchange columns. We compared this method with a conventional separation method using three ion exchange columns (AG50W-X8, AG1-X8, and Chelex-100) for a natural zinc ( nat Zn) target irradiated by a proton beam. The product quality and the recovery rate with the new method were competitive with the conventional method, and the total operation time was reduced from 1 day to <3 h.

This study was carried out to evaluate the effect of the various gamma dose irradiations on the antioxidant activity of rosemary PBS (phosphate-buffered saline) extract. The PBS extract of rosemary was irradiated with gamma rays at the doses of 10, 20, 30, 40 and 50 kGy, and their antioxidant activities were investigated by DPPH (1,1-diphenyl-2-picrylhydrazyl), radical cation ABTS •+ (2,2-Azino-Bis (3-Ethylbenzthiazoline-6-Sulfonic Acid), Diammonium Salt), ferric reducing antioxidant power assay (FRAP) and ferric chelating capacity using ferrozine. The scavenging activities of gamma irradiated rosemary were observed to be significantly higher at 30 and 40 kGy using both methods, DPPH and ABST. Also, the reducing power values of 30 kGy gamma irradiated rosemary were higher than that of non-irradiated (P < 0.05) and the other doses of irradiation could not make any significant difference in reducing power of non-irradiated rosemary. The gamma irradiation of rosemary (at 10–50 kGy), significantly increased the Fe 2+ chelating activity compared to non-irradiated rosemary while increasing the absorbed doses reduced Fe 2+ chelating activity in rosemary (P < 0.05). There is no significant difference in the rosemary irradiated with 10 kGy and 30 kGy. The gamma irradiated rosemary showed higher antioxidant activities at doses of 30 kGy (79.5 %) and 40 kGy (80 %) with DPPH method, while slightly lower activities were recorded at doses of 30 kGy (34.8 %) and 40 kGy (34.2 %) with ABTS test. Also, results indicate that the 30 kGy might be an effective dose with maximum enhancement in the antioxidant properties of the gamma irradiated rosemary.

The design of organic/inorganic nanoparticles hybrids provides the great potential for the fabrication of γ-ray sensor systems. Herein, structural and dosimetric properties of the gamma irradiated poly vinyl acetate (PVAc) doped with cadmium telluride quantum dots (CdTe QDs) and graphene oxide (GO) nanoflakes have been investigated. Thioglycolic acid (TGA) capped water-soluble CdTe QDs and (GO) nanoflakes are synthesized and characterized. Then, CdTe QDs/GO/PVAc sensors were formed by post-depositing CdTe and GO over polymer matrix. The photophysical interactions between nanoparticles and organic polymer have been investigated using ohmic contact detectors with two gold coated electrodes. Real time dose rate information of the sensors such as sensitivity, repeatability, and the linearity of dose rate response were assessed. A wider photoelectric response range and wider gamma harvesting range were observed in the resultant hybrid gamma sensor at a standard bias voltage with respect to non-hybrid CdTe QDs/PVAc sensors.

The aim of this study is to investigate the radiological quality of drinking waters consumed in Nevşehir province which is the most important tourism destination of the Cappadocia region. The activity concentration of gross α- and β-emitting from natural radionuclides ( 238 U, 234 U, 230 Th, 226 Ra, 210 Po, 232 Th and 210 Pb, 228 Ra and 40 K) in 21 tap water samples supplied by municipal pipelines were analyzed by using a gas proportional α/β counter. The average activity concentrations of the gross α and gross β in tap water samples were found as 88 ± 10 mBq L −1 and 305 ± 32 mBq L −1 , respectively. The average natural activity concentrations of α- and β-emitting radionuclides in tap water samples are below the limit values recommended by the Turkish regulation and WHO. For all samples, except for one sample, the gross β activity concentrations are higher than the corresponding gross α concentrations. The average annual effective radiation dose (AERD) due to the ingestion of these water samples was estimated to be 43, 60 and 124 μSv year −1 for infants, children, and adults, respectively. The average of AERD estimated for adults is 24 % higher than the dose limit of 100 μSv year −1 . The activity concentration results reveal that tap water samples are acceptable for human consumption in accordance with the Turkish regulation and WHO recommendations for drinking water.

In this study, radon concentration measurements and chemical analyses of groundwater samples were performed in four sampling locations of Bartın Province of Western Black Sea Region, Turkey. 222 Rn analysis was carried out in groundwater samples with liquid scintillation counting system in accordance with ASTM D5072 standard. The pH, total hardness, alkalinity and dissolved oxygen parameters of the groundwater samples were also determined. The radon concentrations for the water samples ranged between <3.00 Bq/L–12.03 Bq/L. Thirty eight percentage of the samples slightly exceeded the permissible limit of 11.1 Bq/L specified by USEPA for drinking waters. The annual effective doses of groundwater samples were calculated in the range of 7.41–30.74 μSv/y for ingestion of water ( E w.Ig ), and in the range of 7.31–30.31 μSv/y for inhalation of radon released from water ( E w.Ih ). The total calculated annual effective doses due to ingestion and inhalation were found to be below the limit value of 100 μSv/y specified by the World Health Organization (WHO). The radioactivity measurement results significantly varied for three sampling points but not for one sampling point on two different measurement dates, which is attributed to the differences in geological structure. The chemical analysis results, except for total hardness in two sampling points, were within the permissible limits specified by international standards.