Volume 100, Issue 1 -

Experimentally measured cross sections are presented for the nat Cu( α , xn ) 66,67,68 Ga and 68 Zn( p , xn ) 67,68 Ga nuclear processes up to 36 and 20 MeV, respectively. Based on these results and the reliable cross section data available in the literature, the possible thick target yields were also calculated. Two different 68 Ga production routes (Cu+ α and Zn+ p ) are discussed in detail, especially with regard to the 66 Ga and 67 Ga contamination levels as a function of the target enrichment level and the incident bombarding energies. Both processes can be used for in-house 68 Ga production with low (<1%) 66 Ga and/or 67 Ga EOB contamination using enriched 68 Zn (>80%) or 65 Cu (>95%) target. The maximum available yield on 100% enriched 68 Zn and 65 Cu (irradiation time: 2.25 h; bombarding energy: E p =20 MeV and E α =18 MeV) is 352.45 mCi/μA (13.04 GBq/μA) and 14.28 mCi/μA (528.36 MBq/μA), respectively.

In this paper we report an investigation on the interactions between dioxouranium(VI) and citrate using potentiometry (H + -glass electrode) and UV-spectrophotometry. Potentiometric measurements were carried out in NaCl and KNO 3 aqueous solutions at t = 25 ºC in a wide range of experimental conditions (concentrations, ligand/metal molar ratio, pH, titrants). Measurements in NaCl were carried out at different ionic strength values (0.1 ≤ I /mol L −1 ≤ 1.0); different procedures were employed for the acquisition of experimental data and careful analysis of these data performed. In all cases the speciation model that best fits experimental data takes into account the formation of the following species: UO 2 (Cit) − , (UO 2 ) 2 (Cit) 2 2− , (UO 2 ) 2 (Cit) 2 (OH) 2 4− , (UO 2 ) 2 (Cit) 2 (OH) 3− , (UO 2 ) 2 (Cit)(OH) 2 − , (UO 2 ) 2 (Cit)(OH) 0 , (UO 2 ) 3 (Cit) 2 (OH) 5 5− . The dependence on ionic strength of formation constants was taken into account by using both a simple Debye–Hückel type equation and the SIT (specific ion interaction theory) approach. Moreover, a visible absorption spectrum for each complex reaching a significant percentage of formation in solution (KNO 3 medium) has been calculated to characterise the compounds found by pH-metric refinement. Recommended values for the uranyl-citrate species were proposed for each ionic strength values in NaCl aqueous solution. Comparison with literature stability constants is reported too.

A procedure has been developed for the decontamination of radioruthenium from the lean organic phase composed of a solution 0.2 M n -octyl(phenyl)- N,N -diisobutylcarbamoylmethylyphosphineoxide (CMPO) and 1.2 M tri- n -butylphosphate (TBP) in n -dodecane ( n -DD), which was used for the partitioning of minor actinides from actual high active waste solution (155 GWd/Te). For this purpose, the stripping behavior of radioruthenium from 0.2 M CMPO–1.2 M TBP in n -DD was studied at 298 K by using various aqueous reagents and adsorbents. Among the different reagents investigated, the aqueous solution of sodium hydroxide and sodium carbonate and adsorbents such as neutral alumina and anion exchange resin (OH - form) were identified as the promising candidates. Nearly 90–95% of radioruthenium was removed from the lean organic phase in seven contacts using sodium carbonate or sodium hydroxide solution. The residual radioactivity in the organic phase was removed by treatment with neutral alumina or anion exchange resin. The quality of the organic phase was ascertained by 241 Am(III) retention test.

Hydrolytic and radiolytic stability of T(2EH)TDGA solvent system has been investigated to establish its application in separation and recovery of palladium from High Level Liquid Waste (HLW) solutions. Hydrolysis of T(2EH)TDGA solvent system with nitric acid was not observed. Moreover, unlike other “S” donor extractants used for the said purpose, the oxidation of thioetheric sulphur to sulphoxide or sulphones was also not observed. However, radiolytic degradation was notably observed and found to increase with increase in absorbed dose. n -dodecane was found to sensitize the degradation of T(2EH)TDGA. At gamma radiation dose of 0.2 MGy, no significant loss of T(2EH)TDGA was observed. The degradation products were identified by GC-MS. The major products were found to be formed by cleavage of thioetheric and amidic bonds of T(2EH)TDGA molecule. The extraction studies of palladium with irradiated solvent indicate that with 0.025 M T(2EH)TDGA/ n -dodecane, there was no significant change in D Pd up to an absorbed dose of 0.2 MGy above which it decreases significantly. However, with 0.05 M T(2EH)TDGA/ n -dodecane, there is gradual decrease in D Pd with increase of absorbed dose. Further, the radiolysis does not affect the stripping behavior of palladium. Extraction studies of Pd(II) and other fission products from simulated high level liquid waste (SHLW) solutions to irradiated solvent system showed that, except palladium, any other element is hardly extracted thus retaining its remarkable selectivity.

Concentrations of 210 Po in fish and shellfish, mostly collected from southern region of Japan were analyzed. Values ranged from 0.2 to 229 Bq/kg fresh weight and higher concentrations were observed in samples analyzed with viscera. Intake of 210 Po through fish and shellfish was evaluated at different Japanese cities based on statistical consumption data. Phytoplankton, Heterosigma akashiwo was collected during a harmful algal bloom and 210 Po was analyzed. The phytoplankton occupied only 4.4% of 210 Po in seawater and a large fraction of 210 Po was observed in the particulate form.

This study shows the application of semi-absolute k 0 instrumental neutron activation analysis ( k 0 -INAA), epithermal neutron activation analysis (ENAA) and atomic absorption spectrophotometry (AAS) for the determination of 21 elements (Br, Ca, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sc Sr, and Zn) in different types of milk samples. The ENAA was required for the determination of iodine, AAS for Cu, Ni and Pb and the rest of the elements were measured by k 0 -INAA. Thirteen elements (Br, Ca, Cl, Cs, Cu, Fe, K, Mg, Na, P, Rb, Sr and Zn) were identified in all milk samples. Ni was detected in eleven and Pb in two samples. Concentrations of most of the elements were within the ranges of the world reported data. The data was further explored by principal component analysis to find relationships between samples and elements.

Various trace elements in different types of iron based geological reference materials [JSS 804-1 (hematite), JSS 820-2 (limonite), SU-1 and SU-1a (iron-nickel-copper-cobalt ores)] were investigated using k 0 -instrumental neutron activation analysis ( k 0 -INAA). To avoid the interference of iron as the matrix element, a liquid–liquid extraction procedure with diisopropyl ether (DIPE) in hydrochloric acid solution and determination of trace elements in the inorganic phase was undertaken prior to irradiation. The k 0 -INAA method, applied to determine the content of the investigated elements, enabled the distribution of 39 elements to be followed through their corresponding intermediate/medium and long half-lived radionuclides. The possibility of determining the content of numerous trace elements after Fe separation is an important advantage of the proposed method. k 0 -INAA used to determine element s in the powdered materials and in liquid form after iron extraction enabled us to follow the losses and potential contamination of some elements in the liquid–liquid extraction process. Additionally, elimination of the matrix element lowered the detection limit for some trace elements compared to their corresponding values obtained by k 0 -INAA.