Band 108, Heft 12

Four different techniques were applied for the production of 233 U alpha recoil ion sources, providing 229 Th ions. They were compared with respect to a minimum energy spread of the 229 Th recoil ions, using the emitted alpha particles as an indicator. The techniques of Molecular Plating, Drop-on-Demand inkjet printing, chelation from dilute nitric acid solution on chemically functionalized silicon surfaces, and self-adsorption on passivated titanium surfaces were used. All fabricated sources were characterized by using alpha spectrometry, radiographic imaging, and scanning electron microscopy. A direct validation for the estimated recoil ion rate was obtained by collecting 228 Th recoil ions from 232 U recoil ion sources prepared by self-adsorption and Molecular Plating. The chelation and the self-adsorption based approaches appear most promising for the preparation of recoil ion sources delivering monochromatic recoil ions.

Uranium ore concentrates (UOCs), the product of uranium mining and milling, are primarily comprised of uranium oxide (U 3 O 8 and UO 2 ) or peroxide (UO 4 ·4H 2 O and UO 4 ·2H 2 O) compounds. Following production, UOCs are typically placed in storage until they are converted to uranium hexafluoride (UF 6 ) at a uranium conversion facility. In this study, the chemical changes responsible for an interesting hardening phenomenon observed in UOCs stored for prolonged periods was investigated to understand underlying causes. Powder X-ray diffraction and thermogravimetric analysis were used to characterize free-flowing and hardened UOC samples and revealed the hardened material had undergone hydration and oxidation as indicated by increased moisture content and the presence of metaschoepite [(UO 2 ) 4 O(OH) 6 ](H 2 O) 5 and/or schoepite [(UO 2 ) 4 O(OH) 6 ](H 2 O) 6 . Additionally, an aging study found metaschoepite in UOCs after 3 months exposure to a high relative humidity environment. The same study found agglomerated, but not fully hardened, material in nearly all aged UOCs samples. These results suggest metaschoepite and schoepite are indicative of UOCs exposed to elevated levels of H 2 O during storage. Lastly, a drying/calcining study of hardened U 3 O 8 material demonstrated a means of remediation and identified an intermediate compound of potential interest, dehydrated schoepite. Dehydrated schoepite results from heating metaschoepite or schoepite between 100 and 300 °C and indicates partial reversal of hardened U 3 O 8 to its original condition.

Part weakly alkaline natural uranium-containing water contains abundant Ca 2+ and (bi)carbonate. Herein, two kinds of materials, namely mesoporous hydrous manganese dioxide (MHMO) and polyacrylonitrile (PAN)/dolomite composites were synthesized and characterized to evaluate their adsorption behaviors of U(VI) from Ca 2+ coexisted bicarbonate solution. Characterization results showed that both samples exhibited good structural stability after U(VI) load. MHMO could coordinate U(VI) through the surface –OH sites, whereas an unfavorable U(VI) adsorption onto mineral composites was deduced. Adsorption tests indicated that increasing Ca 2+ and (bi)carbonate amounts suppress U(VI) adsorption process, and ∼19.0 mg/g U adsorbed by MHMO could be obtained in solutions with 1 mmol/L [Ca 2+ ], 5 mmol/L [CO 3 ] T , 50 mg/L [U(VI)] initial at pH 8.0. Moreover, a heterogeneous surface chemical adsorption was verified through kinetics and isotherms study. Results from our study should be useful in exploring the adsorption behaviors and mechanisms of U(VI) on selected inorganic and mineral materials from natural uranium-containing water.

Unwanted targeting of healthy organs caused by the relocation of radionuclides from the target site has been one of the limiting factors in the widespread application of targeted alpha therapy in patient regimens. GdVO 4 nanoparticles (NPs) were developed as platforms to encapsulate α -emitting radionuclides 223 Ra, 225 Ac, and 227 Th, and retain their decay daughters at the target site. Polycrystalline GdVO 4 NPs with different morphologies and a zircon-type tetragonal crystal structure were obtained by precipitation of GdCl 3 and Na 3 VO 4 in aqueous media at room temperature. The ability of GdVO 4 crystals to host multivalent ions was initially assessed using La, Cs, Bi, Ba, and Pb as surrogates of the radionuclides under investigation. A decrease in Ba encapsulation was obtained after increasing the concentration of surrogate ions, whereas the encapsulation of La cations in GdVO 4 NPs was quantitative (∼100%). Retention of radionuclides was assessed in vitro by dialyzing the radioactive GdVO 4 NPs against deionized water. While 227 Th was quantitatively encapsulated (100%), a partial encapsulation of 223 Ra (∼75%) and 225 Ac (>60%) was observed in GdVO 4 NPs. The maximum leakage of 221 Fr (1st decay daughter of 225 Ac) was 55.4 ± 3.6%, whereas for 223 Ra (1st decay daughter of 227 Th) the maximum leakage was 73.0 ± 4.0%. These results show the potential of GdVO 4 NPs as platforms of α -emitting radionuclides for their application in targeted alpha therapy.

The 16 α -[ 18 F]Fluoroestradiol ([ 18 F]FES) is an established PET radiotracer for estrogen positive (ER+) breast cancer. Although the radiosynthesis is well-described, the majority of the published methods suffer from modest or irreproducible yields and time-intensive purification procedures. In view of the considerable clinical applications, development of a more efficient and faster synthesis of [ 18 F]FES still remains a task of a significant practical importance. [ 18 F]FES was produced by a direct nucleophilic radiofluorination of 3- O -methoxymethyl-16,17-O-sulfuryl-16-epiestriol (MMSE), followed by acidic hydrolysis using HCl/CH 3 CN. [ 18 F]Fluoride retained on a QMA carb cartridge (46 mg) was eluted by solution of 1.2 mg of tetrabutylammonium tosylate (TBAOTs) in EtOH. After fluorination reaction (0.3 mg MMSE, 1 ml of CH 3 CN/100 °C, 5 min) [ 18 F]FES was isolated by single-cartridge SPE purification using OASIS WAX 3cc, elution accomplished with aqueous ethanol of different concentrations. On а GE TRACERlab FX N Pro automated module [ 18 F]FES (formulated in normal saline with 5% EtOH) was obtained in 33 ± 3% yield ( n  = 5, non-decay corrected) within 32 min. Reduction of precursor amount, exclusion of azeotropic drying step and simplification of purification make the suggested method readily adaptable to various automated synthesizers and offers significant cost decrease.

This work describes the purification and separation of some radionuclides of 210 Pb and/or 210 Bi that might be used in calibration of nuclear spectroscopic instruments for forensic purposes and environmental studies. The retention and desorption investigations have been done by Dowex HCR-S/S resin as the cationic exchanger by batch mode. Full retention of metal ions was achieved in 0.1 M HNO 3 solution after an equilibration period of 2 h at room temperature. The uptake of Pb and Bi is reached to more than 95 and 85%, respectively. Desorption studies by several reagents indicated that 1 M citric acid and ammonium acetate are efficient to elute and separate Bi and Pb. Taking into consideration all the above obtained results, column applications packed by the Dowex HCR-S/S resin were carried out to separate 214,210 Pb and 214 Bi radionuclides either in TENORM-concentrate or old certified reference of 226 Ra solution. The column application results revealed that the recovery of Pb and Bi radionuclides was ∼93%. In the radiochemical part, the eluted Bi was impure due to presence of 23% Pb. In contrast, 70% of pure Pb was obtained. Thus, the radionuclides 210 Pb can be recovered from several waste resources by this method. It can be concluded that the Dowex HCR resin can be an alternative economic material that could be used to produce 210 Pb from the TENORM wastes generated from some strategic industries.

Einkorn ( Triticum monococcum L.) is accepted as the oldest known wheat. In this study, the natural radionuclide and essential metal contents of siyez samples collected from 21 different cultivation areas in Kastamonu province located in the Western Black Sea region of Turkey were determined by using non-destructive analytical methods. The average activity concentrations of 40 K, 226 Ra and 232 Th measured in siyez samples using a gamma-ray spectrometry were found as 181.3 ± 4.1, 10.0 ± 0.7 and 6.1 ± 0.2 Bq kg −1 , respectively. The average annual effective radiation dose that the people are exposed to due to the consumption of siyez samples was estimated as 68.2 ± 3.1 µSv y −1 . The average concentrations of Cr, Mn, Fe, Co, Ni, Cu and Zn essential trace metals analyzed in einkorn samples using EDXRF spectrometry were found as 3.6 ± 0.2, 89.2 ± 1.2, 208.5 ± 62.6, 16.8 ± 0.6, 12.1 ± 0.1, 8.3 ± 0.2 and 65.3 ± 2.5 mg kg −1 , respectively.