bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural and artificial radionuclides in forest and bog soils: Tracers for migration processes and soil development
Authors: Schleich N. , Degering D. , Unterricker S.
Published: August 2006

Radionuclide distributions in undisturbed forest and bog soils, mostly situated in Saxony, Germany (Erzgebirge), were studied. Low concentrations of naturally-occurring U and Th decay series nuclides, including 210Pb, and artificial radioisotopes (125Sb, 134Cs, 137Cs, 241Am) were determined using low-level γ-spectrometry. In addition, the activities of 238Pu and 239,240Pu were determined by radiochemical separation and α-spectrometry. 14C and excess 210Pb dating methods were used to date the sampled bog profiles. The different radionuclides show characteristic depth distributions in the forest and bog soil horizons, which were sub-sampled as thin slices. 125Sb, 241Am, 238Pu and 239,240Pu are strongly fixed in soil organic matter. In spruce forest soils, the influence of soil horizons with distinct properties dominates the vertical time-dependent distribution. In ombrotrophic bogs, the peak positions correlate with the year of maximum input of each nuclide. The Sb, Am and Pu “time markers“ and the 14C and 210Pb dating results correspond very well. Although Cs seems to be relatively mobile in organic as well as mineral forest soil horizons, it is enriched in the organic material. In ombrotrophic bogs, Cs is very mobile in the peat deposit. In Sphagnum peat, Cs is translocated continuously towards the growing apices of the Sphagnum mosses, where it is accumulated.
Distribution of natural radionuclides during the processing of phosphate rock from Itataia-Brazil for production of phosphoric acid and uranium concentrate
Authors: Fukuma H.T. , Fernandes E.A.N. , Quinelato A.L.
Published: August 2006

A high-uranium phosphate rock from the Itataia deposit, located in the state of Ceará, Brazil, was milled in a pilot plant for wet-process phosphoric acid production. Further processing with solvent extraction (DEHPA/TOPO) was used aiming to recover uranium from the phosphoric acid. The distribution of natural radionuclides with long physical half-life of the 238U and 232Th decay series involved in these operations was evaluated. The radionuclides 226Ra, 228Ra and 210Pb were found to predominate in the phosphogypsum, while 228Th, 230Th and 232Th in the uranium-free phosphoric acid.
Reactivity of 99mTc(V) ''3+1''mixed-ligand complexes towards glutathione
Authors: Gupta A. , Seifert S. , Syhre R. , Scheunemann M. , Brust P. , Johannsen B.
Published: August 2006

The stability and reactivity of mixed-ligand 99mTc complexes of the general formula [99mTcOL1L2], where L1H2 is either an N-substituted bis-(2-mercaptoethyl)amine [SNMeS] or 3-thiapentane-1,5-dithiol [SSS] and L2H is a monodentate thiol [RS], were investigated. The complexes undergo transchelation reactions with glutathione and other SH-group containing blood constituents. The reactions are reversible and can be inhibited by addition of diethylmaleate. Challenge experiments were performed with a broad set of 99mTc mixed-ligand complexes to investigate the influence of both the tridentate ligand and the monodentate ligand on the stability of this type of complex. The occurrence of ligand exchange reactions with glutathione depends on the donor set of the tridentate ligands as well as the structure of the monodentate ligands. Especially the stability of complexes containing a monodentate ligand with an amine nitrogen in the side chain can be increased by lengthening the carbon chain between the sulfhydryl group and the nitrogen. Thus, it might be possible to improve their in-vivo performance.
The "age" of plutonium particles
Authors: Wallenius M. , Tamborini G. , Koch L.
Published: August 2006

Age determination of plutonium particles is a highly important task in view of the pending cut-off treaty for nuclear weapons materials. By collecting particles from the vicinity or inside the nuclear facilities and determining their ages, it is possible to monitor the observance of the cut-off agreement.

In this study, the age determination of Pu particles was demonstrated by Secondary Ion Mass Spectrometry (SIMS). To determine the ionisation efficiency difference of Pu and U, standard Pu materials with known ages were analysed. Finally, the age determination of two real Pu samples was demonstrated.
Catalytic reduction of pertechnetate (99TcO4
-) insimulated alkaline nuclear wastes
Authors: Bernard J.G. , Bauer Estelle , Richards M.P. , Arterburn J. B. , Chamberlin R.M.
Published: August 2006

Pertechnetate ion (99TcO4
-, 10-4 M) in alkaline solution is quantitatively reduced to hydrous TcO2 by thermolysis (65 °C, 4 days) in the presence of organic complexants and fission-product noble metals (RuCl3,

RhCl3, and PdCl2; 0.001 M). Over 99% reduction occurs in the presence of ethylenediaminetetraacetic acid (EDTA), hydroxyethyl(ethylenediaminetriacetic acid) (HEDTA), or glycolic acid valunit{0.050}{M}). Nitrilotriacetic acid (NTA), oxalic acid, and citric acid provide ≤ 2% reduction. Ruthenium, rhodium, and palladium chlorides also catalyze the reduction of TcO4
- by hydrogen gas. The results are consistent with a two-step process of complexant degradation to generate H2, followed by catalytic reduction of pertechnetate to hydrous TcO2 or soluble technetium complexes. Catalytic reduction is a viable, non-radiolytic route to the formation of non-pertechnetate species of 99Tc in alkaline nuclear wastes, e.g., Hanford tank wastes.
Diffusion of99Tc in granite: A small scale laboratory simulation experiment
Authors: Liu C. L. , Wang X. Y. , Li S. S. , Wang Z. M. , Gao H. C. , Li B. , Wen R. Y. , Wang H.F. , Tang L. T. , Xin C. T. , Jiang L.
Published: August 2006

The diffusion of99Tc in granite was investigated with small-sized diffusion cells, composed of a radioactive source solution cell and a sampling cell. Water in the two cells was kept at the same level. 1 ml aliquots were taken from the sampling cells daily during the first 50 days, then at intervals of several days, and measured via liquid scintillation counting. The experimental results indicate that the diffusion of99Tc and3H in granite follows the one-dimensional diffusion equation when diffusion time is long enough (>100 days). The calculated average diffusion coefficient of99Tc (1.4×10-12m2/s) is about one half of that of3H (3.2×10-12m2/s).
Separation and speciation of fission products by zirconium phosphate prepared by solid-solid reaction
Authors: El-Said N. , Siliman A. M. , El-Sherif E. , Mikhail A. S.
Published: August 2006

Zirconium phosphate hase been prepared by solid-solid reaction. The characterization of this inorganic ion exchanger was done with respect to capacity, pH titration, dissolution, etc. The preconcentration and separation of fission products, Sr(II), Co(II), Eu(III), Gd(III), Hg(II) and Am(III) has been achieved from different acidic media, HCl, HNO3, H2SO4, HClO4. The speciation of these cations in different media has been investigated. From the results obtained, it is obvious that these cations can be preconcentrated in low acidic medium, whilst at high acidity in the range 1-2 M, they be can separated from each other.
Interaction study between Ca2+ and humic acids in brine media
Authors: Laszak I. , Choppin Gregory R.
Published: August 2006

The interaction between Ca2+ and humic acids (HA) was studied at ionic strengths from 0.10 to 5.0 m (NaCl) by the solvent extraction technique. The dependence of the stability constants upon pcH (4.7 to 9.0) was interpreted by the polyelectrolyte model of HA. The data was consistent with formation of a single Ca-HA complex.
223Ra for endoradiotherapeutic applications prepared from an immobilized227Ac/227Th source
Authors: Henriksen Gjermund , Hoff P. , Alstad J. , Larsen R. H.
Published: August 2006

A method is described for the production of223Ra (t1/2=11.4 d) in a quality useful for endoradiotherapeutic applications. The method is based on a long term operating generator with a source of227Ac (t1/2=21.7 years), from which223Ra is eluted. The227Ac was isolated from a231Pa source using the f-element selective extraction chromatographic material TRU-resin. The purified227Ac/227Th source was subsequently applied to another extraction chromatographic resin, containing the extractant P,P′-di(2-ethylhexyl)methanediphosphonic acid on silica (Dipex-2) and used as a generator for223Ra. From the generator column, the yield of223Ra was about 60 kBq per 100 kBq of227Ac with a highly effective separation of223Ra from the precursors. In production runs, the activity of227Ac was found to be 6×10-6relative to the eluted activity of223Ra. By using a second column of Dipex-2 for additional purification, the activity of Ac was reduced to below 7×10-8relative to223Ra with nearly quantitative recovery of223Ra. The described procedure resulted in a high purity223Ra preparation, potentially useful in,e.g., targeted radiotherapy of tumors.
Radiochemical study on the mechanism of target fragmentation of Cu, Nb, Pr and Au targets induced by 12C and 40Ar projectiles
Authors: Yokoyama Akihiko , Morimoto S. , Araki H. , Sanada J. , Baba H. , Shinohara Atsushi , Shibata S. , Saito T. , Ohkubo Y.
Published: August 2006

A thick-target thick-catcher experiment was performed to measure the formation cross sections and recoil momenta of products from target fragmentation of Cu, Nb, Pr, and Au by using gamma-ray spectrometry. Bombardments of C ions (180, 290, and 400 MeV/u) and Ar ions (290 and 650 MeV/u) were performed at the HIMAC facility in Japan. The results were discussed in comparison with systematics of fragmentation and used to deduce the prefragments in fragmentation process of the measured systems.
Metal ion - molecule reactions of Bk+: comparison with Pu+ and Tb+
Authors: Gibson John K. , Haire Richard G.
Published: August 2006

Gas-phase reactions of the bare monopositive berkelium ion, Bk+, with several reagents were examined by a mass spectrometric technique adapted for the highly radioactive transuranium actinides. The earlier actinide ion, Pu+, and the homologous lanthanide ion, Tb+, were studied simultaneously to enable effective interpretation of the results in the context of the electronic structure and energetics of berkelium. Reactions with several alkenes, as well as butylamine and butyronitrile, revealed that the metal-ion mediated dehydrogenation efficiency decreased in the order: Tb+>Pu+>Bk+. The products included (π-bonded) organoberkelium products such as BkC8H8
+, presumably the berkelium-cyclooctadienylide "half-sandwich" complex ion. The reactivity results are consistent with C-H activation by metal ion insertion to form C-M+-H activation complexes, and indicate that the a 5f electron of ground state Bk+ must be promoted to a 6d orbital to provide two non-5f valence electrons for the two covalent bonds in these σ-bonded organoberkelium intermediates. Reactions of Bk+ with hexafluoropropene, dimethylether and methylvinylether also indicated lower reactivities compared with Pu+ and Tb+. Products included berkelium alkoxide and fluoride molecular ions. The experiments reported here are an extension of a systematic study of gas-phase actinide ion chemistry, with Bk-249 now being the shortest-lived isotope for which such studies have been carried out (half-life =320 days). The results are in accord with those for more reactive Cm+ and less reactive Cf+, which indicated essentially lanthanide-like behavior in this region of the actinide series and chemically inert (localized) 5f electrons. Large differences between the gas-phase chemistries of Bk+ and Tb+ reflect substantial discrepancies between the electronic energetics of homologous members of the two series, consistent with spectroscopic measurements. Bond dissociation energies, BDE[M+-O], of 655 and 610 kJ mol-1 were for estimated for PuO+ and BkO+, respectively.
Physico-chemical characterization of seaborgium as oxide hydroxide
Authors: Hübener S. , Taut S. , Vahle A. , Dressler R. , Eichler B. , Gäggeler H. W. , Jost D.T. , Piguet D. , Türler A. , Brüchle W.
Published: August 2006

Seaborgium (Sg; element 106) was studied in comparison with tungsten in the O2-H2O(g)/SiO2(s)-system using high temperature on-line isothermal gas chromatography. The 21-s nuclide266Sg was produced in the248Cm+22Ne reaction at a beam energy of 119 MeV. The reaction products were continuously transported by a He(MoO3)-jet to the chromatography apparatus HITGAS. Group 6 element oxide hydroxide molecules volatile at temperatures above 1000 K were formed at 1325 K by adding humid oxygen as reactive gas.266Sg was unambiguously detected after gas chromatographic separation by measuring266Sg-262Rf mother-daughter α-sf correlations. The experimental results demonstrate the volatility of Sg in humid oxygen, presumably as Sg oxide hydroxide, a behavior typical for both U(VI) and the group 6 elements.
ISOLDE target and ion source chemistry
Authors: Köster U.
Published: August 2006

For the production of radioactive ion beams by means of the ISOL (isotope separation on-line) method in which the nuclei of interest are stopped in a thick target, chemistry plays a crucial role. It serves to separate the nuclear reaction products in atomic or molecular form from the bulk target and to transfer them efficiently to an ion source. This article gives an overview of ISOLDE radiochemical methods where targets (liquid metals, solid metals, carbides and oxides) and ion sources are optimized with respect to efficiency, speed and chemical selectivity. Rather pure beams of non-metals and volatile metals can be obtained with a temperature-controlled transfer line acting as thermo-chromatograph. For less volatile metals the temperature of the target and ion source units needs to be kept as high as possible, but a selective ion source can be used: positive surface ionization for metals with ionization potentials below about 6 eV and the RILIS (resonance ionization laser ion source) technique for most other metals.
Development of digital autoradiography technique for the determination of the platinum-group elements in geological materials
Authors: Kolotov V.P. , Shilobreeva S.N. , Andriyanov A.Yu. , Dogadkin N.N. , Chapyzhnikov B.A. , Alenina M.V.
Published: August 2006

Application of digital document scanners as a tool for 2D-densitometry of autoradiograph images is discussed. Comparison with conventional densitometry is presented. The requirements for scanners and software for digital autoradiography of geological materials are reviewed and a selective and sensitive method for the detection of platinum by means of gamma-activation autoradiography has been developed (the detection limit is about 1 ng for Pt-inclusions in spinel). The results of an interpretation of neutron-activation autoradiographs for locating an iridium-containing phase is discussed.
Use of extraction chromatography for thorium purification from Eskisehir-Beylikahir Thorium-REEs ore deposit
Authors: Hiçsönmez Ü. , Eral M.
Published: August 2006

The extraction chromatography method was used to separate thorium from acidic leach solution. The separation of thorium was realized on silica gel column coated with tri-octlyphosphine oxide (TOPO). The extraction yield of thorium on this column from nitric acid leach solution is 91.9%. Then thorium was eluted by using 0.5 M H2SO4 solution, and elution yield was determined as 96.5%. The chemical analysis of H2SO4 fractions indicated that thorium was concentrated and purified succesfully by this method. As a result, thorium was recovered in dilute leach solution with a yield of 81.0±6.8%.
On the origin of129I in rain water near Zürich
Authors: Schnabel C. , Lopez-Gutierrez J.M. , Szidat S. , Sprenger M. , Wernli H. , Beer J. , Synal H.-A.
Published: August 2006

129I concentrations in precipitation at Dübendorf/Zürich, Switzerland, have been determined with monthly resolution for almost three years in the mid 1990s. The results confirm that annual mean129I concentrations in precipitation in central Europe have remained about constant since the late 1980s. Liquid and gaseous emissions from the nuclear fuel reprocessing plants at Sellafield and La Hague are discussed as the only possible sources of129I in precipitation in central Europe. Based on an upper limit estimate for iodine transferred from the sea to the atmosphere, the gaseous discharges constitute the potentially bigger129I reservoir for precipitation. Moreover, the time dependence of the annual gaseous129I releases from Sellafield and La Hague correlates much better with the129I concentrations in precipitation in central Europe since the late 1980s than does the time dependence of the liquid emissions from these sites. At monthly resolution, the129I concentrations in the precipitation samples close to Zürich exhibit a large variability. A meteorological transport analysis was carried out for four selected months with particularly low or high observed129I concentrations. It was found that meteorological transport alone, based upon assimilated wind fields and observed precipitation values, can not directly account for the large month-to-month variability.
Continuous on-line calibration of diffusive soil-atmosphere trace gas transport using vertical 220Rn- and 222Rn-activity profiles
Authors: Lehmann B.E. , Neftel A. , Tarakanov S.V.
Published: August 2006

Continuous monitoring of 220Rn- and 222Rn-activities above and below the soil surface combined with sporadic direct 222Rn-flux measurements is used to quantify diffusive trace gas transport in the air-filled pore space of soil, through the soil-atmosphere interface and in the lowest layers of the atmosphere. In a calm night, 222Rn-activities above the surface first build-up near the ground (z<10 cm) and subsequently with a delay of 2-3 hours at higher altitudes (z<5 m). Knowing (1) the 222Rn-flux from activity profiles measured in soil gas, (2) from direct flux determinations and (3) using information about atmospheric diffusion parameters from 220Rn-activities measured near the surface it is possible to model the temporal evolution of the vertical 222Rn-profiles in a night with stable weather and constant soil conditions. The system operates automatically for extended periods of time in the field enabling a better understanding of transport processes in response to changing environmental conditions (wind, rain, soil humidity).
A radiochromatograpic study of the reaction of 51CrO3 with hydrochloric acid
Authors: Pezzin S.H. , Collins C.H. , Collins K.E.
Published: August 2006

The objective of the present work is to verify the reduction of CrO3 in concentrated hydrochloric acid, using 51Cr as a tracer. For the study, 51CrO3 was added to 37% HCl and maintained under agitation at 20 °C for specified time periods. Aliquots were diluted to approximately pH 2 and analyzed by open column cation and anion chromatography, either immediately or after storage for specified time periods. The separations, which were made by stepwise elution using HClO4 and Ca(ClO4)2 solutions as eluents with fraction collection, followed by counting with a NaI(Tl) detector and a single channel analyzer, permitted construction of elution profiles whose peaks were identified by comparison with authentic samples. The results show that CrO3 is reduced to Cr(III) in 37% HCl and that the initial identifiable product is [CrCl3(H2O)3], a product which undergoes slow aquation at pH 2 to [Cr(H2O)4Cl2]+, [Cr(H2O)5Cl]2+ and [Cr(H2O)6]3+.
Gallium-67 production at Bucharest U-120 classical cyclotron
Authors: Constantinescu B. , Simion C.
Published: August 2006

A new route was investigated for the production of the medically interesting radionuclide 67Ga (T½=78.1 h, EC∼100%) at Bucharest low energy U-120 classical cyclotron. Details on the preparation of this radionuclide via natural Zn(p,n)67Ga nuclear reaction and chemical processing (extraction followed by column separation) are described.
Alternative syntheses of [73,75Se]selenoethers exemplified for homocysteine[73,75Se]selenolactone
Authors: Ermert J. , Blum T. , Hamacher K. , Coenen Heinz H.
Published: August 2006

The present work describes two radiosynthetic pathways to prepare homocysteine[75Se]selenolactone 1 starting from n.c.a. [75Se]selenite 2. It was achieved either by alkylation reaction of n.c.a. methyl[75Se]selenide 4 or by hydrolysis of alkylated 1,3-dicyclohexyl[75Se]selenourea 11.

N.c.a. methyl[75Se]selenide 4 is available using sulfur as non-isotopic carrier. However, the radiochemical yield of the substitution of 2-tert.-butoxycarbonylamino-4-bromobutyric acid ethylester 5 with n.c.a. methyl-[75Se]selenide is only in the range of 15-20%. Birch reduction of protected n.c.a. [75Se]selenomethionine 6 formed leads to a RCY of 5-10% homocysteine[75Se]selenolactone 1.

Alternatively, the synthesis of homocysteine[75Se]selenolactone 1 is possible by hydrolysis of the corresponding [75Se]selenouronium salt 11 available by addition of 2-tert.-butoxycarbonylamino-4-bromobutyric acid ethylester 5 to 1,3-dicyclohexyl[75Se]selenourea 10. A method was developed for the synthesis of 1,3-dicyclohexyl[75Se]selenourea 10 by addition of c.a. [75Se]SeH2 to 1,3-dicyclohexylcarbodiimide, which leads to 20-30% RCY of c.a. homocysteine[75Se]selenolactone 1.
Liquid-liquid extraction of plutonium and americium by cekanoic acid from alkaline medium
Authors: Chetty K. V. , Sagar V. , Swarup R.
Published: August 2006

Liquid-liquid extraction studies of plutonium and americium from aqueous carbonate medium using a high molecular weight carboxylic acid namely cekanoic acid in different diluents has been carried out. The distribution ratio (D) values for Pu(IV) and Am(III) under various parameters such as concentration of extractant, Na2CO3and initial pH were obtained. Results indicated that Pu(IV) and Am(III) could be satisfactorily extracted together or individually from aqueous carbonate medium using cekanoic acid in different diluents like carbon tetrachloride, cyclohexane, toluene, n-dodecane or solvesso-100. The D values for Pu(IV) and Am(III) also indicated the possibility of their mutual separation. The back extraction of Pu and Am with different reagents was also studied.
Absorption of iodine from aqueous solutions on nuclear reactors alloys
Authors: Bayri B. , Rosset R. , El Kacemi K.
Published: August 2006

Iodide ions I-, molecular iodine I2 and iodate ions IO3
- absorption has been studied on the three alloys which are present, in majority, in french nuclear reactors: Inconel 600, Zircaloy and 304L stainless steel.

Iodide and iodate anions are not absorbed on the three considered alloys and contribute only for a negligible quantity to iodine retention on the nuclear reactors materials. Molecular iodine is absorbed according to:

304 stainless steel < Zircaloy < Inconel 600.

Influence of pH has been studied: absorption increases in acidic medium and decreases in basic medium. Molecular iodine absorption increases with temperature.Phenomenons which occur with iodine during the cold shutdown of a nuclear reactor and during its restart are discussed from the point of vue of iodine volatilization risk.
Radiocesium removal from high level liquid waste and immobilisation in sodium silicotitanate for geological disposal
Authors: Tomasberger T. , Veltkamp A.C. , Booij A. S. , Scherer U. W.
Published: August 2006

The isolation of the fission product cesium from high-level alkaline liquid waste is studied with inorganic ion-exchange materials. High separation and concentration factors can be obtained using sodium silicotitanate (CST). The leaching behaviour of cesium from CST was studied in clay porewater and Quinary brine at 90 °C. It is shown that cesium leaching in Quinary brine can be drastically reduced by thermal treatment of cesium loaded CST above 1000 °C. To this end, neutralisation of the ion exchange material before heating is required in order to reduce cesium volatility. It is concluded that CST is a good candidate material for geological disposal of the fission product cesium.
Hot test of partitioning strontium from high-level liquid waste (HLLW) by dicyclohexano-18crown-6 (DCH18C6)
Authors: Jianchen W. , Chongli S.
Published: August 2006

The crown ether strontium extraction(CESE) process for partitioning strontium from HLLW was studied. A hot test was carried out in a counter current mode with genuine HLLW by using a miniature centrifugal contactor set. 0.1 mol/L DCH18C6 in 1-octanol was used as extractant. The feed solution was the HLLW raffinate of TRPO process after removing TRU elements. Acidity of the feed was 1.45 mol/L HNO3. In the hot test 10 extraction stages and 2 scrubbing stages were used in the extraction section. Four stripping stages were used in the backextraction section. The results of the hot test were very attractive. More than 99.96% of strontium were extracted from the feed solution and above 99.84% strontium was stripped out of the organic phase. Non of the TRU elements was extracted with strontium by the extractant. Only about 0.4% of Cs were extracted and found in the Sr stripping stream. The hot test result proved that the CESE process was a promising process to remove strontium from HLLW.
Evaluation of resonance ionization mass spectrometry for the determination of 135Cs/137Cs isotope ratios in low-level samples
Authors: Pibida L. , Nörtershäuser W. , Hutchinson J.M.R. , Bushaw B.A.
Published: August 2006

The ability of Resonance Ionization Mass Spectrometry (RIMS) to reliably determine the ratio of 135Cs/137Cs in the presence of large backgrounds has been evaluated. Single-resonance excitation of Cs 6s 2S1/2(F=4)→6p 2P3/2(F'=5) with an extended cavity diode laser was followed by photoionization with the 488 nm line of an argon ion laser. While the principal objective was to avoid isobaric interferences, an optical selectivity of 3 orders of magnitude against stable 133Cs was attained for both 135Cs and 137Cs. The overall RIMS efficiency was found to be ∼ 2×10-6 with a combined (laser and mass spectrometer) selectivity of ∼ 1010 for both 135Cs and 137Cs against 133Cs. The performance with respect to efficiency, selectivity, and isobar suppression has been compared to conventional thermal ionization mass spectrometry (TIMS). Measurements to determine the chronological age of a burn-up sample have been performed using both methods.
Overview of nuclear data libraries and online services
Authors: Schwerer O. , Obloinský P.
Published: August 2006

This paper summarizes the various nuclear data types and libraries available free of charge from the IAEA Nuclear Data Section, many of which are relevant to medical applications. The databases are collected, maintained and made available within the framework of an international nuclear data centers network. Particular emphasis is given to online services via the Internet. The URL address of the IAEA Nuclear Data Services is http://www-nds.iaea.or.at.
Hadrons (protons, neutrons, heavy ions) in radiation therapy: rationale, achievements and expectations
Authors: Wambersie A. , Gahbauer R.A.
Published: August 2006

The safety, efficacy and reliability of photon beams is well established; however, new types of beams continue to be introduced and explored with the aim of achieving improved selectivity from better dose distribution or from radiobiological mechanisms. Fast neutrons were the first non-conventional radiation used in cancer therapy. Fast neutrons, a form of high-LET radiation, were introduced for the following radiobiological reasons: (1) a reduction of the OER with increasing LET, (2) a reduction in the difference in radiosensitivity related to the position of the cells in the mitotic cycle, (3) less repair and thus less clinical relevance of the different repair mechanisms. The best, clinically proven, indications for fast neutrons are salivary gland tumours, locally advanced prostatic adenocarcinomas and slowly growing, well differentiated sarcomas. Proton beams brought a significant improvement in the physical selectivity. Worldwide, the number of proton therapy centres in operation and in the planning stage increases continuously. The best clinical results so far have been reported for uveal melanoma, tumours of the base of skull, and some brain tumours in children. Heavy ions combine the advantage of better physical selectivity of protons with the radiobiological advantages of fast neutrons for some tumour types. Heavy ions were applied at Berkeley from 1975 to 1992, and at NIRS in Chiba since 1994. A pilot study started at GSI-Darmstadt in 1997. Boron neutron capture therapy (BNCT) aims at a physical selectivity at the cellular level; it is still in an experimental phase.
Nuclear reactions in proton, neutron, and photon radiotherapy
Authors: Chadwick M.B.
Published: August 2006

This review article provides an overview, for medical physicists, of recent work that addresses the role of nuclear reactions in proton, fast neutron, and conventional photon radiation therapy. Nuclear reaction cross sections have been evaluated, in ENDF format, for use in Monte Carlo radiation transport simulations of radiotherapy, in order to optimize the absorbed dose to a tumor. The evaluations utilize both measured cross section data as well as nuclear model calculations of direct, preequilibrium, and Hauser-Feshbach compound processes. In the case of photonuclear reactions, giant dipole resonance and quasideuteron photoabsorption mechanisms are considered.
Extraction of heptavalent technetium from nuclear waste streams with 2-nitrophenyl octyl ether
Authors: Chen J. , Boerrigter H. , Veltkamp A.C.
Published: August 2006

Technetium-99, in the form of Tc(VII), is one of major problems in the management and disposal of nuclear waste in view of its long half-life in combination with high geochemical mobility. Solvent extraction is an important separation technique to remove99Tc from liquid nuclear waste streams. 2-nitrophenyl octyl ether (NPOE) shows high extraction ability for Tc(VII) from water and NaOH solutions (>99.5%) in spite of the lack of donating atoms. Upon extraction from alkaline solutions, TcO4-associates with NPOE molecules in 1:1 stoichiometry where the co-extracted cation is expected to play an important role in the extraction mechanism. At pH > 4 the Tc(VII) distribution is relatively insensitive towards changes in pH, while at decreasing pH (<4) the distribution ratio decreases sharply. The strong dependency of the Tc(VII) distribution on the acidity is very useful for developing efficient extraction-stripping systems. This study showed that NPOE is an excellent compound for the removal of technetium from alkaline nuclear wastes.
Determination of cumulative yields of fission products from 238U by 5.0 MeV neutrons
Authors: Celenk I.
Published: August 2006

By using a spectrum average technique, the cumulative yields of the fission products of 238U were determined at 5.0 MeV neutron energy. In the determination, the 115In(n,n′)115mIn reaction was used as a monitor. The gamma spectra of the fission products and those of the monitor were taken by using a REGe detector with Be window. The determined values were corrected for contribution from the 235U(n,f)reaction. The results were compared with predicted values from EXFOR data file.
Plutonium(IV) peroxide formation in nitric medium and kinetics Pu(VI) reduction by hydrogen peroxide
Authors: Maillard C. , Adnet J.-M.
Published: August 2006

Reduction of plutonium (VI) to Pu(IV) with hydrogen peroxide is a step in industrial processes used to purify plutonium nitrate solutions. This operation must be carefully controlled, in order to avoid any formation of the Pu(IV) peroxide green precipitate and to obtain exclusively Pu(IV). This led us to study the acidity and Pu and H2O2 concentrations influenceson the precipitate appearance and to perform a Pu(VI) reduction kinetic study on a wide range of acidities ([HNO3]: 0.5 to 8 M), plutonium concentrations ([Pu(VI)]: 0.1 to 0.8 M) and [H2O2]/[Pu(VI)] ratio (from 1 to 8). Thus, the domain of Pu(IV) peroxide formation and the reactional paths were established.

With the exception of 0.5 M nitric acid medium, the kinetic curves show two distinct regims: the first one corresponds to an induction period where the Pu(VI) concentration doesn´t change, the second corresponds to a linear decrease of Pu(VI). An increase of the temperature greatly accelerates the Pu(VI) reduction rate while [H2O2]/[Pu(VI)] has almost no influence. The Pu(VI) total reduction time decreases when initial concentration of plutonium increases. By increasing nitric acid concentration from 0.5 M to 6 M, the total Pu(VI) reduction time decreases. This time increases when [HNO3] varies from 6 M to 8 M.
Thermodynamics of the PuO2+-Na+-OH--Cl--ClO4--H2O system: use of NpO2+Pitzer parameters for PuO2+
Authors: Rai Dhanpat , Moore Dean A. , Felmy Andrew R. , Choppin Gregory R. , Moore Robert C.
Published: August 2006

Obtaining reliable thermodynamic data for Pu(V) is difficult because of its redox and/or disproportionation reactions in most aqueous systems. The known stability of Pu(V) in PuO2(am) suspensions in slightly acidic to near neutral conditions was used to study the solubility of PuO2(am) in 0.4 and 4.0 M NaCl or NaClO4solutions ranging in pcH+values from 4 to 9 as a function of time. The close agreement between the observed solubility and the predicted solubility using Pitzer ion-interaction parameters of Np(V) with Cl-or ClO4-for Pu(V) indicates that Pu(V), as expected, behaves in an analogous fashion to Np(V) and confirms the value of using Np(V) data to model Pu(V) behavior.
Complexation behaviour of neptunium with humic acid
Authors: Seibert A. , Mansel A. , Marquardt Christian M. , Keller H. , Kratz Jens Volker , Trautmann N.
Published: August 2006

The complexation of Np(V) with humic acid (HA) was studied under environmental conditions (pH≥6, concentration of HA 1-150 mg/L) over a wide range of metal ion concentrations (10-14to 10-4mol/L). The experimental methods used for the determination of the complexation constants were continuous electrophoretic ion focusing, anion exchange, and ultrafiltration in combination with radiometric measurements, and, as a direct speciation method, UV/Vis-spectroscopy. The interaction between Np(V) and humic acid has been described with the charge neutralization model including a correction for different loading capacities (LC) which makes possible the comparison of results obtained at various experimental conditions. Furthermore, the degree of deprotonation has also been used to calculate the complexation constants. The complexation constants calculated for Np(V) with the LC-concept vary with the metal ion concentration in the range between 10-14and 10-4mol/L. At metal concentrations below 10-11mol/L, a complexation constant logβLC=5.0±0.3 was obtained. In the concentration range 10-7to 5×10-4mol/L, the logβLCvalues decrease continuously to 3.7±0.4 (10-5-5×10-4mol/L). The latter is in agreement with direct measurements (UV/Vis-spectroscopy) at this concentration and data from the literature.
Technetium(VII) transport across supported liquid membranes (SLMs) containing 2-nitrophenyl octyl ether (NPOE)
Authors: Chen J. , Boerrigter H. , Veltkamp A.C.
Published: August 2006

Technetium is one of key issues in the treatment of radioactive liquid waste because of its long half-life in combination with high fission yield and its geochemical mobility. For the removal of Tc(VII) from water and concentrated alkaline solutions, 2-nitrophenyl octyl ether (NPOE) is a very effective extractant. In this paper we describe the application of supported liquid membranes (SLMs) impregnated with NPOE for the removal of Tc(VII) from these solutions by using 1.5 M HNO3 receiving phase solutions. Transport of Tc(VII) across a SLM was evaluated with a mechanistic model using a permeability coefficient P to describe the rate of transport. SLM transport of Tc(VII) with NPOE is completely membrane diffusion limited and that there are no aqueous resistances. The membrane diffusion coefficient D

m
was calculated to be D

m
=6.4×10-13 m2/s. Permeability is highest for transport from pure water source solution, with P = 3.2×10-4 cm/s. From NaOH solutions the permeability decreases slightly. For acidic source phase the permeability is even lower due to the poor extraction yields of Tc(VII) from acidic solutions into NPOE. Counter current transport of H+ does not affect the extraction and permeability. The Tc(VII)-NPOE system is very robust, only small quantities of NPOE are needed, and the membrane distribution and permeability coefficients are sufficiently large for practical applications.
Detection of radioactive hot particles in environmental samples using a Marinelli-beaker measuring geometry
Authors: Bunzl K. , Tschiersch J.
Published: August 2006

The presence of one or more hot particles in environmental samples (e.g., soil) in a Marinelli beaker on a HPGe detector can be detected by repeated mixing and counting, and subsequent application of a statistical test to examine whether the observed counts belong to the same Poisson distribution. The method is, however, only efficient if the photons from different random positions of a point source in the Marinelli beaker produce sufficiently different count rates. For a detector with a Be-window, as used here, this is the case for the low-energy photons of 241Am and to a somewhat smaller extent for the high energy photons of 137Cs. As a result, even in the presence of a considerable background activity of the sample matrix, the presence of up to 5 hot particles can be detected by five repeated mixing and counting processes with a probability of >95% for 241Am, but only with a probability of 86% for 137Cs (assuming that about 1000 counts are recorded each time). The easiest way to increase this probability substantially is to increase the counting time or increase the number of mixings. If self adsorption of the photons within the sample occurs, or if the hot particles have different activities, the probability to detect their presence by this method is also increased. An efficiency calibration for the counting geometry used is not required.
Präzisions-Effektivwertmessung nach der „Monte-Carlo-Methode” (Precision RMS Measurement using the Monte Carlo Method)
Authors: Germer H. , Barnet U.
Published: August 2006

Die Messung von Effektivwerten ist mit herkömmlichen Verfahren und Geräten oft nur unter bestimmten Voraussetzungen und mit mäßiger Genauigkeit möglich, oder sie erfordert einen hohen apparativen und zeitlichen Aufwand. Im Folgenden wird ein neuartiges Verfahren beschrieben, mit dem Präzisionsmessungen von Effektivwerten nicht sinusförmiger Messsignale in einem weiten Frequenzbereich möglich sind. Das Verfahren arbeitet nach dem Monte-Carlo-Prinzip, einem stochastischen Abtastverfahren. Ein nach diesem Prinzip arbeitendes Gerät wurde durch die Physikalisch Technische Bundesanstalt geprüft und kalibriert. Die Fehler liegen im Frequenzbereich 30 Hz bis 70 Hz unter 0,01 % bezogen auf den Messbereichsendwert.
Mehrwellenlängen-Interferometrie zur absoluten Abstandsmessung und 3D-Bildgebung (Multiple-Wavelength Interferometry for Absolute Distance Measurement and Three-Dimensional Imaging)
Authors: Trautner J. , Walcher K. , Leuchs G. , Bodermann B. , Telle H.R.
Published: August 2006

Mit einem absolut messenden, interferometrischen Abstandssensor wird aus großer Entfernung die dreidimensionale Gestalt rauer Objektoberflächen erfasst. Der Sensor arbeitet nach dem Prinzip der Mehrwellenlängen Interferometrie. Zur Messung der interferometrischen Phasen wird die Heterodyntechnik verwendet. Die Tiefenauflösung des Sensors wird nur durch die Rauigkeit der Objektoberfläche beschränkt. Wir demonstrieren das 3D-Messverfahren bei einer Messentfernung von ungefähr einem Meter an Objekten von wenigen Millimetern bis mehreren Zentimetern Höhe. Mit einer Integrationszeit von 60 ms wird dabei eine Tiefenauflösung von wenigen 10 μm erreicht.
Kalibrierung des faseroptischen Ortsfilter-Einpunkt-Durchflussgebers (Calibration of the Fiberoptical One-Point Flow Meter Characterized by Spatial Filtering)
Authors: Petrak D. , Mahr P.
Published: August 2006

Mittels gravimetrischer Normalmesseinrichtung mit einer Messunsicherheit ≤5·104wurde die Messunsicherheit eines faseroptischen Ortsfilter-Einpunkt-Durchflussgebers zu 5,5·103festgestellt. Die stabförmige Messsonde wurde in einer wasserdurchströmten Rohrleitung DN 100 so positioniert, dass sich das optische Messvolumen auf der Rohrachse befindet. Die Berechnung des Volumenstroms erfolgte anhand angegebener Beziehungen der Strömungsgeschwindigkeitsprofile.
Verlustfreie Echtzeit-Kompression von Echolotdaten (Lossless Real-Time Compression of Ultrasonic Data)
Authors: Wunderlich J. , Strutz T.
Published: August 2006

Bei der Erkundung des Meeresbodens mit hydroakustischen Verfahren entstehen große Datenmengen, insbesondere wenn für die Ortung von Objekten eine hohe räumliche Auflösung nötig ist. In diesem Beitrag wird untersucht, wie der zur Archivierung der Daten benötigte Speicherplatz durch Datenkompression minimiert werden kann. Es wird ein optimierter Algorithmus zur verlustfreien Kodierung von Echolotdaten vorgestellt und mit verschiedenen im PC-Bereich verbreiteten universellen Kompressionsprogrammen hinsichtlich Verarbeitungsgeschwindigkeit und Kompressionsrate verglichen.
Parametertrennung in Sensoren und Messsystemen durch Signalverarbeitung (Parameter Separation in Sensors and Measuring Systems through Signal Processing)
Authors: Liu Ji-Gou , Becker Wolf-Jürgen , Gerhold T. , Ricken Werner
Published: August 2006

Parametertrennung in Mess- und Sensorsystemen spielt eine wichtige Rolle für Messungen physikalischer Größen, insbesondere für den Fall, dass die Wirkung der Messgröße auf das Ausgangssignal viel kleiner als die der Einflussgrößen ist. In diesem Beitrag wird eine verbesserte Kompensationsmethode durch Signalverarbeitung unter Verwendung einer neu definierten komplexen Zwischengröße dargelegt. Die Trennung einer eindimensionalen Einflussgröße wird an 2m+1 Kompensationspunkten durchgeführt, während die Trennung einer mehrdimensionalen Einflussgröße mit 2nKompensationspunkten realisiert wird. Durch Verwendung dieser Methode wurden bei der Messung an vorgespannten Stahlbetonkonstruktionen der Temperatureinfluss und bei Abstandsmessung mittels Wirbelstromsensoren in der Betriebsmesstechnik die Materialabhängigkeit zusammen mit dem Einfluss der Sensorposition wesentlich reduziert.
Grundlagen zur industriellen Einsetzbarkeit des Kohärenzradars (Fundamentals for the Industrial Applicability of the Coherence Radar)
Authors: Blossey S.
Published: August 2006

Für den potenziellen Anwender im BMBF-Forschungsverbund war es das Ziel, die Eignung des 3D-Sensors „Kohärenzradar” für typische Messaufgaben im industriellen Umfeld zu testen. Ein transportabler Portalaufbau des Sensors wurde realisiert, um Tests vor Ort durchführen zu können. Eine in den Aufbau integrierte x/y-Verschiebeeinheit erlaubt zudem, bestimmte Regionen einer zu messenden Objektoberfläche anzufahren oder auch größere Messfelder sukzessive zu vermessen. Ein Kalibrationsverfahren wurde konzipiert und umgesetzt, mit dem der Sensor in allen Raumrichtungen einfach kalibriert werden kann. Für die industrielle Anwendung ist ein werkergerechtes und automatisierbares Bedienen ebenso wichtig wie eine sinnvolle Aufbereitung der gewonnenen Messdaten. Beides ist durch die Anbindung des Kohärenzradars an eine spezielle Ansteuer- und Auswertesoftware möglich geworden. Da wichtige Applikationen für das System im Bereich der Oberflächenmesstechnik liegen, wurde das Kohärenzradar mit taktilen Oberflächenmessgeräten verglichen; unter gewissen Voraussetzungen eignet sich der Sensor für Rauheitsmessungen.
Schätz- und Korrekturverfahren des Biasfehlers der LDA-Messungen mit oder ohne Richtungserkennung (Method for Estimating and Correcting the Bias of the LDA Measurements with or without Direction Detection)
Authors: Shu W.-Q.
Published: August 2006

Die durch Laser-Doppler-Anemometer (LDA) gemessene mittlere Geschwindigkeit der turbulenten Strömung ist mit einem Biasfehler behaftet. Bisherige theoretische Untersuchungen darüber sind mangelhaft. In der vorliegenden Arbeit wird eine exakte analytische Lösung abgeleitet, die sowohl LDA mit Richtungserkennung als auch ohne Richtungserkennung umfasst. Außerdem wird nicht nur der Biasfehler der mittleren Geschwindigkeit, sondern auch der des Turbulenzgrades behandelt. Das entsprechende Korrekturverfahren wird vorgestellt.
Streifende-Inzidenz-Interferometrie mit diffraktiven Elementen für die Formmessung von Mantelflächen stabförmiger Objekte II:Experimente und Fehlerdiskussion (Grazing Incidence Interferometry Using Diffractive Optical Elements for the Shape Measurement of the Mantle Surface of Rod-shaped Objects II: Experiments and Error Assessment)
Authors: Brinkmann S. , Dresel T. , Schreiner R. , Schwider J.
Published: August 2006

Dies ist Teil II des zweiteiligen Artikels (Teil I: siehe tm 1/2000) über die Streifende-Inzidenz-Interferometrie. Hier werden die Auswertemethoden, Messbeispiele für technische Objekte, wie (1) Ebene, (2) Zylinder und (3) mathematisch konvexe Objekte und (4) allgemeine Meridiankurven von Stäben, die auftretenden systematischen Fehler aufgrund des Prinzips aber auch aufgrund der Herstellgenauigkeit lithographischer Maschinen und schließlich auch noch Erweiterungen in den mittleren IR-Bereich diskutiert. Um die Übersicht zu erleichtern, sind die Kapitel fortlaufend nummeriert, beginnend mit Kapitel 9.
Wavelets: Eine praxisorientierte Einführung mit Beispielen, Teil 1 (Wavelets: An Introduction for Potential Users, Part 1)
Authors: Best R.
Published: August 2006

Über Wavelets sind viele Aufsätze und Bücher geschrieben worden, die vor allem mathematisch ausgerichtet sind. Der Einstieg für den (potentiellen) Anwender ist meist beschwerlich, da er sich erst durch mathematisches Dickicht quälen muss und überdies wenige Hinweise auf praktische Anwendungen findet. Diese Fortsetzungsreihe packt das Thema „Wavelets” aus der Sicht des Ingenieurs/Physikers an, der sich darüber orientieren möchte, was Wavelets überhaupt sind, und wozu er diese allenfalls benutzen kann. Die vorliegende Reihe beginnt mit einer anschaulichen Einführung in die Welt der Wavelets. Danach werden die wichtigsten Wavelet-Anwendungen diskutiert, und zwar vor allem die Datenkompression (Audio, Video) sowie die Zeit-Frequenz-Analyse von Signalen.
Statistischer Fehler der Mittenfrequenzmessung am Beispiel von Laser-Doppler-Signalen (Statistical Measuring Error of the Centre Frequency of Laser Doppler Signals)
Authors: Czarske J.
Published: August 2006

Es wird auf die Quadratur-Demodulation-Signalverarbeitungstechnik (QDT) zur Messung der Frequenz von photoelektrischen Signalen eingegangen. Die QDT ist dadurch ausgezeichnet, dass präzise Frequenzmessungen von Signalen mit wenigen Perioden oder sogar nur einem Periodenbruchteil vorgenommen werden können. Die Messung von kleinen Signalfrequenzen kann daher mit einer hohen Zeitauflösung erreicht werden. In diesem Aufsatz wird auf den Fehler der QDT-Frequenzmessung eingegangen. Insbesondere wird die Standardabweichung der Frequenz von verrauschten, pulsförmigen Laser-Doppler-Signalen bestimmt. Der Fragestellung, welche Mittelungszeitdauer in Bezug zur Pulsdauer gewählt werden sollte, um eine minimale Standardabweichung zu erreichen, wird näher nachgegangen.
Dynamische Temperaturkompensation von Präzisionsmessgeräten (Dynamical Temperature Compensation of Precision Instruments)
Authors: Fröhlich T. , Jäger G.
Published: August 2006

Durch die Temperaturkompensation von Präzisionsmeßgeräten kann deren Empfindlichkeit gegenüber störenden Temperatureinflüssen deutlich gesenkt werden. Bei der dynamischen Temperaturkompensation werden Temperaturen an mehreren Positionen gemessen und deren Dynamik zur Kompensation verwendet. Zwischen der Reproduzierbarkeit der Temperaturmessung und den möglichen dynamischen Modellen der Temperaturabhängigkeit existiert ein Zusammenhang, der bei der Modellidentifikation verwendet werden kann. Am Beispiel einer elektronischen Präzisionswaage wird die Wirkung einer dynamischen Temperaturkompensation gezeigt.