Volume 100, Issue 7 -

A method for preparation of 67 Cu based on deuteron irradiation of enriched 70 Zn is presented. Cross-sections for 67 Cu formation were determined by the stacked foil technique for deuteron energies in the range from 10 to 20 MeV for the first time. Irradiations of 70 Zn foils were followed by radiochemical separation of 67 Cu from the target material and co-produced radionuclidic impurities. The maximum cross-section value of 25.5 ± 2.2 mb was reached at 19 MeV. The integral yield in the energy window of 20 → 10 MeV on 95% enriched 70 Zn is estimated at 4.2 MBq/μA h (110 μCi/μA h) or 375 MBq/μA (10 mCi/μA) at saturation.

The extractants, bis(2-ethylhexyl)diglycolamicacid (HDEHDGA) and bis(2-ethylhexy)thiodiglycolamic acid (HDEHSDGA) were synthesized and characterized by 1 H and 13 C NMR, mass and IR spectroscopy. The extraction behaviour of (152+154) Eu(III) and 241 Am(III) from nitric acid medium by a solution of HDEHDGA (or HDEHSDGA) in n -dodecane ( n -DD) was studied for the mutual separation of actinides and lanthanides. The effect of various parameters such as the pH, concentrations of HDEHDGA, HDEHSDGA, sodium nitrate, N , N , N´ , N´ -tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and diethylenetriaminepentaacetic acid (DTPA) on the separation factor (SF) of americium(III) over europium(III) and vice versa was studied, and the conditions needed for the preferential separation were optimised. The results show that HDEHDGA exhibits higher extraction for (152+154) Eu(III) and HDEHSDGA shows the superior selectivity for 241 Am(III).

This paper deals with radiochemical procedures for U and Th determination ( 238 U, 234 U, 232 Th and 230 Th) via alpha spectrometry in water and sediment samples. After checking a separation process based on chromatographic extraction (using UTEVA resins), a detailed comparison with another separation process (liquid–liquid solvent extraction using tri- n -butyl phosphate-TBP) has been performed. Both separation processes were applied in environmental liquid and solid samples and the two separation methods were compared in order to find the more suitable separation process attending on parameters such as chemical yields, interference elimination, time-consuming, reagents used and generated wastes, among others. As major result, we can indicate the UTEVA separation process as a better option than TBP in U and Th isotopes determination by alpha-particle spectrometry.

Experimental studies on the selectivity of Chelex-100 resin for the separation of actinide cations at different oxidation states (III, IV, V and VI) from aqueous solution have shown that Chelex-100 presents increased selectivity for actinyl cations at near neutral pH (pH ∼ 4.5). The effect of salinity on the chemical recovery indicates that the increased selectivity could be attributed to the formation of complexes with specific interactions and the pH area, in which the formation of the respective complexes is favored, indicates the occurrence of guest-host interactions. The specific interaction of Chelex-100 with actinyl cations could be of particular interest not only for the separation and preconcentration of uranium from natural waters prior its analysis but also for the recovery of uranium from seawater on a large scale.

The reaction between aqueous hydrogen peroxide solutions and hydrogen has been studied at room temperature and in the absence of catalytic products. The concentrations of the hydrogen peroxide solutions used are in the level expected to be obtained by water radiolysis in the vicinity of spent nuclear fuel surface. On the other hand, different hydrogen pressures were used, with a maximum of 48 bars, which mimics the maximum pressure postulated as a result of iron-steel containers anoxic corrosion. The reaction evolution has been determined by the decrease of hydrogen peroxide concentration with time. A clear effect has been observed, and the rate of reaction is found to be enhanced as the hydrogen pressure is increased. From the experiments performed, a kinetic constant k= 0.029 ± 0.009 dm 3 mol −1 s −1 has been determined for the reaction H 2 O 2 + H 2 (g) → 2H 2 O based on a second-order overall kinetics reaction (first order with respect to hydrogen peroxide and first order with respect to hydrogen).

In order to deal with the potential highly increasing amount of high-level radioactive wastes and spent nuclear fuels along with the ambitious development of nuclear power plants, China needs to construct a geologic repository in the middle of the 21 st century. After about 15 years of basic research, including site survey, radionuclide migration, Beishan area in Northwest China's Gansu Province has been considered as the most promising candidate place. The Beishan granite has been highly considered as one of the potential host rocks, and some geochemical and hydrogeologic work has been carried out with the granite. In terms of pre-safety assessment of a potential site, the sorption, diffusion and migration of important radionuclides which tend to be released from the potential repository in the rock/water system play an important role and must be thoroughly investigated with the site specific rock/water characteristics. Due to the potential mobility of technetium under repository conditions, the investigation of the diffusion of technetium in different potential rocks has been studied, while few work focused on the rock surface characteristics. Since the diffusion/migration of radionuclides in the potential host rocks of geologic repositories is mainly through the pores/fractures of the host rocks, the surface characteristics of the rocks should play non-negligible role. In this paper, the influence of pH in the rock/water system on the diffusion of 99 TcO 4 − in Beishan granite is investigated with through-diffusion experiments and batch sorption experiments. Experimental results indicate that the effective diffusion coefficients ( D e ) of 99 Tc in Beishan granite varied from 9.7 × 10 −13 to 1.3 × 10 −12  m 2 /s, and the distribution coefficients ( K d ) of 99 Tc in Beishan granite decreased when the pH of the rock/water system increased which may due to the decreasing of the density of positively charged sites on the granite surface.

Radionuclides with medium energy beta emission and a several day half-life are attractive candidates for radioimmunotherapy. Among the most promising in this category is 47 Sc produced by fast neutron irradiation ( E n >1 MeV) of titanium target with high energy neutrons in 47 Ti( n,p ) 47 Sc nuclear reaction. In the previously reported production scheme the dissolution of the TiO 2 target in hot concentrated H 2 SO 4 and evaporation of the resulting solution were the most time-consuming steps. The present paper describes new, simple and efficient production method of 47 Sc, where the slow dissolution of the target is avoided. After irradiation in fast neutron flux 47 TiO 2 and Li 2 47 TiF 6 targets were dissolved in HF solutions. Next 47 Sc was separated from the target using anion exchange resin Dowex 1 with 0.4 M HF + 0.06 M HNO 3 solution as eluent. The eluted 47 Sc was adsorbed on cation exchange resin and eluted with 0.5 M of ammonium acetate. The 47 Sc separation yield in the proposed procedure is about 90% with the separation time less than 2 h. The obtained no-carrier-added 47 Sc was used to label DOTATATE conjugate with 96% labeling yield.

A novel zoledronic acid (ZL) derivative, 1-hydroxy-2-(2,4-dimethyl-1 H -imidazol-1-yl)-ethane-1,1-diyldiphosphonic acid (DMIDP, dimezoledronate), was successfully prepared and labeled with 99m Tc in a high labeling yield. The biodistribution in mice shows that 99m Tc-DMIDP has significant advantage regarding bone resorption and clearance from soft tissues compared with 99m Tc-ZL and the clinically widely-used bone-imaging agent 99m Tc-MDP (methylenediphosphonic acid). Kinetics of blood clearance displayed that distribution half-life ( T 1/2 α ) and elimination half-life ( T 1/2 β ) of 99m Tc-DMIDP were 2.53 min and 23.53 min, while those of 99m Tc-ZL were 2.28 and 52.63 min, respectively. Excellent images of the rabbit skeleton can be quickly obtained from 99m Tc-DMIDP, which was faster than 99m Tc-ZL and 99m Tc-MDP. The present findings indicate that 99m Tc-DMIDP possesses excellent potential for application as a novel bone scanning agent.

Targeted alpha therapy has shown promising pre-clinical and clinical results in the fight against cancer. The use of in vivo generators, generating a highly cytotoxic cascade of alpha particles, is attracting increasing interest for clinical application. 225 Ac is one of the nuclides that can serve as an in vivo generator. It is commercially available and provides four alpha particles with a total energy of 28 MeV per 225 Ac decay. However, its alpha emitting daughter nuclides may escape from the target region due to recoil and cause unwanted toxicity in other parts of the body. In this paper, we investigate the feasibility of designing spherical, block-copolymer based nano-carriers (polymersomes) to retain the recoiling daughter nuclides. A Monte Carlo code, called NANVES, has been developed to simulate the range distributions of recoil atoms in different materials and to determine the optimum nano-carriers design. Recoil ranges in planar polystyrene films were determined experimentally and compared to simulations of the experiment, indicating that NANVES may provide accurate results. Simulations of various nano-carriers designs indicate that double-layered polymersomes with a diameter of 800 nm are capable of completely retaining the first daughter nuclide 221 Fr, while the escape fraction of the third radioactive daughter 213 Bi is reduced to 20% and the percentage of alpha particles emitted from escaped daughter products outside the nano-carriers is less than 10%.