Authors:A. Yakushev, S. Timokhin, M. Vedeneev, Xu Honggui, and I. Zvara
An isotope of element 106, namely263106, detected by its spontaneous fission, has been chemically isolated by thermochromatography of oxochlorides. The last one has been compared with short- and long-lived isotopes of Mo and W. Two chemical species were observed, presumably MO2Cl2 and MOCl4 (M=Mo,W). A kinetic dependence of these two species has been discussed and a chemical form O2Cl2 has been described for the registered atoms of element 106.
The separation of tungstate and perrhenate anions on alumina from aqueous solutions of sodium chloride was investigated in
dynamic conditions. The breakthrough curves for W and Re as the function of the ratio of their concentrations in the solution,
were determined. The flow rate (3 ml/min), pH 2 and NaCl concentration (0.15 mol/l) were kept constant throughout the experiments.
The breakthrough capacities Q0.05, the capacities at C/C0 = 0.5, the total column sorption capacities Q0.9 and the utilization degrees or column efficiencies E, were determined. According to the obtained data the separation factors αW/Re = Qw/QRe were calculated.
Authors:B. Ponsard, J. Hiltunen, P. Penttilla, H. Vera Ruiz, A. Beets, S. Mirzadeh, and F. (Russ) Knapp
The rapidly increasing therapeutic applications of 188Re in nuclear medicine, oncology and interventional cardiology require routine production of large, multi-Curie levels of the 188W parent. The capability and effective coordination of back-up production sites is important to insure that high level 188W/188Re generators are continually available. We have coordinated 188W production at the High Flux Isotope Reactor (HFIR - Oak Ridge, US) with production at the BR2 Reactor (Mol, Belgium) characterized by peak thermal neutron fluxes of 2.51·015 (HFIR) and 1·1015 (BR2) neutrons/cm2·sec, respectively. The long 69-day physical half-life permits receipt of 188W from BR2 within 0.25 T1/2's, even after the 12-day post irradiation cooling required for 187W decay (T1/2 = 24 hours). Since 188W production by double neutron capture of enriched 186W is a function of the square of the thermal neutron flux, HFIR production (4-5 Ci 188W/g 186W/cycle) is higher than at the BR2 (1.0-1.1 Ci/g 186W/cycle). However, the specific activity (SA) of BR2-produced 188W is still about 0.8-0.9 Ci/g after processing at ORNL following shipment from Belgium. This SA is sufficiently high to permit fabrication of 1 Ci generators suitable for clinical use, since simple post elution concentration of the saline bolus (30-50 ml) obtained from the generator can provide samples with high specific volume (1 ml volume). The time periods from reactor push in Mol and completion of processing, fabrication and shipment of generators from Oak Ridge have been 19-21 days. Six campaigns have been successfully completed since 1998, with processed levels of 188W in Oak Ridge from 8-26 Curies/campaign. 188W has been provided to MAP Medical technologies Oy (Tikkakoski, Finland) for fabrication and distribution of generators for use at IAEA-supported research projects in developing countries. We have thus established and demonstrated an effective collaboration between the Studiecentrum voor Kernenergie-Centre d'Etude de l'Energie Nucléaire (SCK·CEN) and ORNL for back-up production of 188W. This collaboration continues to be especially helpful during periods when interruption of HFIR operation is necessary for maintenance and upgrades.
Authors:Sz. Vass, B. Vorsatz, E. Szabó, E. Kelen, B. Keszei, S. Cseh, and S. Saly
A non-destructive simultaneous method has been developed for the rapid determination of Al, Si and K in WO3 powders and W metal powders. The samples were activated by 14 MeV neutrons and the radioactive isotopes identified by their
γ-ray spectra with a 3″×3″ NaI(Tl) detector. Quantitative analysis was carried out by measuring the full energy peak areas.
The determined concentrations of Al, Si and K were above 100, 100 and 500 ppm, the sensitivities being about 20, 10 and 100
The application of K3W2Cl9 as reducing agent in preparation of99mTc-labelled compounds is described. Pertechnetate reduction was carried out in solutions of pH 2 and also of pH 5.5. DTPA, citrate, gluconate, HEDSPA and MDP were successfully labelled. Two types of labelled gluconate complexes were obtained. Complex I exhibited in rats an increased99mTc affinity to kidneys (21%). Complex II exhibited an increased99mTc affinity to bone (8.7%). Two types of labelled HEDSPA preparations were obtained: one yielded 29%99mTc activity in bone, the other type exhibited only 13.4%. The results indicated the absence of mixed complexes.
Thermodynamic calculations predict the formation of hydrochloric acid gas and alkali tungstates during hydrogen reduction
of WO3 doped with alkali chlorides MCl (M=Li, Na, K). The formation of HCl was proved experimentally by simultaneously coupled TG-MS
measurements from RT to 1200C. The formation of HCl is the result of the reaction between MCl, WO3 and water. Ubiquitous traces of moisture in the gas are sufficient for reaction according to WO3+(2+2n)MCl +(1+n)H2O→M2+2nWO4+n+(2+2n)HCl (n=0, 1, 2). Laboratory reduction tests showed that the formed tungstates differ. NaCl and KCl form monotungstates (n=0), while LiCl produces more lithium-rich compounds (n=1, 2). Temperature and humidity, among other process factors, control subsequent reduction of the tungstates to metals.
Authors:R. Shabana, S. Khalifa, S. Abdalla, and H. Aly
Extraction of WO
by Adogen-381, tricaprylmethylammonium chloride, Hyamine 10-X, trioctylphosphine oxide or dibenzylsulphoxide in xylene from HNO3, HCl or H2SO4 acid medium was investigated. Based on the separation factors obtained, the separation of ReO
was elucidated. ReO
was separated from WO
in high radiochemical purity: >99.9% by three successive extractions and strippings using Adogen-381 from HCl or HNO3 acid medium.
Authors:M. Dadachov, R. Lambrecht, and E. Hetheringtion
An improved188W-188Re gel generator based on Zr tungstate is described. The influence of synthesis parameters and pre-treatment conditions on188Re elution yields and the188W breakthrough was studied with 0.15M aqueous solution of NaCl at pH 5.3 to 7.3 as well as with some organic solvents. An elution efficiency of 80% was achieved during 3 month of explotation with 0.15M NaCl at pH=6.3. The188W breakthrough was 10–4 to 10–3%. The188W breakthrough may be decreased to 10–6% when converted into tandem generator with an alumina column. However,188Re yields are reduced by 8–12% with a tandem generator.
Authors:D. A. Ivanov, V. F. Chuvaev, and M. R. Kiselev
By means of DSC, DTA, TG and NMR it was established that the process of cure of epoxy resins induced by aqueous solutions of heteropolyacids consists of two stages, the first one being connected with a catalytic interaction between oligomer and water, and the second one with epoxy-hydroxyl etherification. Analysis of kinetic data shows that the first reaction is diffusion controlled, the second process can be described by pseudo-first order kinetics with activation energy about 40 kJ/M.
Authors:Z. Szeglowski, H. Bruchertseifer, V. Brudanin, G. Buklanov, O. Constantinescu, Dinh Thi Lien, V. Domanov, L. Guseva, M. Hussonnois, G. Tikhomirova, I. Zvara, and Yu. Oganessian
The short-lived isotopes of W and their descendants have been isolated from the products of the bombardment of144Sm with24Mg by a fast continuous ion-exchange method, using HF solution media. The feasibility of this method for isolation of element 106 is discussed.