A sensitive, rapid and selective method for the determination of237Np in urine is described. Neptunium(IV) is isolated by batch-extraction with a slurry of Microthene-710 (microporous polyethylene)
supporting a cyclohexane solution of tri-n-octylphosphine oxide, the slurry is transferred into a column and neptunium eluted
by oxidation to Np(V) with a mixture of HCl+Cl2. After electroplating on a stainless steel disc, neptunium is counted with a solid-state alpha-detector. The final recovery
is 83.2%; the decontamination factors are sufficiently high and the sensitivity limit is suitable for radiotoxicological purposes.
The paper describes the application of extraction chromatography to the determination of several alpha and beta emitters in
biological and environmental samples. Both column extraction chromatography and batch extraction process have been used to
isolate the radionuclides from the samples. The effect of several parameters (extractant concentration, support granulometry,
stirring time, temperature, presence of a complexing agent) on the extraction and elution has been examined. The application
of redox extraction chromatography is also described.
The paper describes the radiochemical and chemical analyses of industrial graphite scraps showing high radioactivity levels. The uranium concentration in some graphite scraps was very high (up to l kBq/g, 7.7%w/w) and its distribution greatly heterogeneus. Some uranium solubility tests carried out on the graphite scraps showed that 60–70% of the element could be dissolved with a buffer solution at pH 4 and that complete dissolution could be obtained by leaching with conc. HNO3 . By taking into account these results it can be concluded that the radioactive contaminant consists of uranium chemically purified and isotopically treated.
Authors:D. Desideri, S. Giuliani, C. Testa, and C. Triulzi
During the last 14 years the Radioecology Laboratory of Parma University and the General Chemistry Institute of Urbino University collaborated on a radioecological programme having the aim to observe the evolution of antropogenic radioactivity in Antarctica in the period 1987-2001. The artificial radionuclides considered were 90Sr, 137Cs, 239+240Pu,238Pu and 241Am. The contamination seems to be higher in the continental environment rather than in the marine one. Mosses, algae and lichens showed the highest values for all radionuclides analyzed. The results prove that the Antarctic continent is interested by radioactive pollution. As far as 137Cs is concerned, a progressive decrease was observed.
Authors:D. Desideri, M.A. Meli, C. Roselli, and C. Testa
The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, 40K) and antropogenic (Pu, 241Am, 137Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. 137Cs and 40K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.
Authors:C. Testa, D. Desideri, M. Meli, and C. Roselli
Suitable separation techniques were prepared for actinide,90Sr and226Ra determinations in environmental and industrial samples. Extraction chromatography with tri-n-octylphosphine oxide (TOPO) and di(2-ethylhexyl) phosphoric acid (HDEHP) solutions was used. IN some cases, a powder of Microthene (Microporous polyethylene) supporting solid TOPO was prepared thus obtaining a material showing better storing and column preparation features.Uranium and226Ra were determined in phosphorites, phosphoric acid and phosphogypsum.Uranium, thorium and226Ra were also measured in the low specific activity scales of hydrocarbon production equipment:226Ra was found to concentrate in some parts of the plant so causing a radiation protection problem.Plutonium and90Sr were measured either in some Mediterranean Sea samples or in environmental samples collected in Antarctica. Some interesting sea sediment profiles were also obtained.All the chemical methods were verified by: a) adding some yield tracers (232U,228Th,242Pu); b) analyzing some certified samples supplied by IAEA and NIST; c) participating in some international intercomparison runs; d) using, when possible, both an analytical and a radiometric method and e) following the radioactivity decay or growth (90Y and226Ra).
Authors:D. Desideri, C. Roselli, C. Testa, A. Bassignani, and P. Finazzi
Research was carried out to evaluate the possible correlation between the uranium content in host rocks and the Rn and daughters concentration in air for two Italian ZnS-PbS mines. As a great variability had been ascertained for222Rn and daughters concentration in the different areas, it appeared of some interest to verify whether this fact was due to a different uranium concentration in the host dolomitic rocks or simply to a ventilation problem. Some rock samples were collected in several places where also radon and daughters were drawn; uranium was determined by fluorimetry and by alpha spectrometry after a chemical separation with a Microthene-TOPO column.222Rn was measured by the scintillation cell method, while the decay products were determined by the Markov and Tsivoglou methods. No correlation could be found between uranium content and radon concentration, but a good linearity was detected between the uranium content and the concentration of Rn decay products (alpha potential energy).
Authors:Jia Guogang, C. Testa, D. Desideri, F. Guerra, and C. Roselli
A sensitive and reliable metbod for the sequential separation and determination of plutonium,241Am and90Sr in soil samples was developed. Plutonium was separated by a Microthene-TNOA column. Then90Y (for90Sr determination) was separated from americium by a HDEHP column after elimination of large amounts of interfering stable
or radioactive nuclides (iron,210Bi and210Po etc.) by an oxalate precipitation and a Microthene-TNOA column. Finally americium was purified by another HDEHP column
and a PMBP-TOPO extraction. A special attention was paid to the decontamination of Pu and Am from210Po and of90Y from210Bi; the relevant decontamination factors resulted greater than 105, 106 and 104 respectively. The detection limits were 1.2 mBq/kg for Pu and 1.7 mBq/kg for241Am and 0.32 Bq/kg for90Sr. The procedure was checked by analyzing three certified samples supplied by IAEA. Some Italian soil samples were also analyzed
giving average yields of 84.9±7.2% for Pu, 57.8±3.2%for Am and 96.7±1.6% for Y; the239+240Pu,238Pu,241Am and90Sr contents (Bq/kg) ranged from 0.347 to 1.53, from 0.013 to 0.048, from 0.126 to 0.556 and from 2.89 to 11.6 respectively
and the average ratios were 0.037±0.017 for238Pu/239+240Pu, 0.357±0.040 for241Am/239+240Pu and 7.0±1.2 for90Sr/239+240Pu.
Authors:D. Desideri, M. Meli, C. Roselli, C. Testa, and S. Degetto
A sequential extraction method consisting of six operationally-defined fractions was used to determine the geochemical partitioning of natural (U, Th,) and antropogenic (Pu, Am, 137Cs) radionuclides in three sediment samples of different origin (Venice Lagoon, Adriatic Sea; Gaeta Gulf, Thyrrhenian Sea; IAEA-367, Enewetak Atoll, Central Pacific Ocean). Fe, Mn, Al, Ti, Ca, Sr, Pb, Ba, K were also determined in the different fractions to get more information about the chemical association of the single radionuclides. The experimental results were compared to those described in the literature for an IAEA-135 Sea Sediment collected in the Irish Sea in front of the Sellafield Plant (UK).