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Sample records for 232th 237np 231pa

  1. Photo fission cross-section of 232Th, 238U and 237Np

    In the present work, photo fission cross-section of 232Th, 238U and 237Np evaluated with the help of fission fragment angular distribution measurements by using Bremsstrahlung radiation from 7.4 MeV to 9.0 MeV have been carried out by employing high efficiency SSNTD technique

  2. Calculation of fusion time scales in 11B + 237Np, 12C + 232Th and 16O + 232Th reactions in a dynamical trajectory model

    There are several theoretical models which treat the fusion process and energy dissipation in heavy ion collision in terms of a fluctuating force represented by the coupling between macroscopic and intrinsic degrees of freedom. One such dynamical model has been developed by Feldmeier (1987), where the properties of the dissipative force are determined from a microscopic picture of particle exchange between two nuclei. The macroscopic shapes of the nuclear system are represented by axially symmetric configuration with sharp surfaces. We have used the above model to calculate the fusion time scales for the systems 11B + 237Np, 12C +232Th and 16O + 232Th at 77, 86 and 104 MeV bombarding energies to examine the effect of mass asymmetry in fusion dynamics. (author). 2 figs

  3. Study of (n,p) and (n,α) cross-sections for 232Th, 231Pa, 233U isotopes

    The study of neutron induced reaction cross-sections in the charged particle emission in this energy region will help us to understand the energy dependence of activation cross-sections in detail, thereby providing a complete database that will lead to better understanding of mechanisms of the nuclear reactions. The present study describes nuclear model calculations of (n,p) and (n,α) reaction cross-sections for 232Th, 231Pa and 233U isotopes

  4. Fission Cross Sections of {209}Bi, {232}Th, {235}U, {238}U and {237}Np for Intermediate Energy Protons and Deuterons

    Yurevich, V I; Yakovlev, R M; Sosnin, A N

    2001-01-01

    Fission cross sections of {209}Bi, {232}Th, {235}U, {238}U and {237}Np have been measured with 1.0-3.7 GeV protons and 1.0 GeV deuterons. The results are compared with other experimental data, available evaluations and predictions of the theoretical model.

  5. Neutron induced fission cross section ratios for 232Th, /sup 235,238/U, 237Np, and 239Pu from 1 to 400 MeV

    Time-of-flight measurements of neutron induced fission cross section ratios for 232Th, /sup 235,238/U, 237Np, and 239Pu, were performed using the WNR high intensity spallation neutron source located at Los Alamos National Laboratory. A multiple-plate gas ionization chamber located at a 20-m flight path was used to simultaneously measure the fission rate for all samples over the energy range from 1 to 400 MeV. Because the measurements were made with nearly identical neutron fluxes, we were able to cancel many systematic uncertainties present in previous measurements. This allows us to resolve discrepancies among different data sets. In addition, these are the first neutron-induced fission cross section values for most of the nuclei at energies above 30 MeV. 8 refs., 3 figs

  6. Delayed neutron and delayed photon characteristics from photofission of 232Th, 235,238U, and 237Np with endpoint Bremsstrahlung photons in the giant dipole resonance region

    A renewed interest in photonuclear reactions was stimulated by applications as radioactive ion beam production, irradiation stations by high energy photons, shielding of electron accelerators, etc. Today, a particular attention is paid to the non-destructive characterization of waste barrels and the detection of nuclear materials, both based on photofission process and the associated delayed neutron (DN) and delayed photon (DP) emissions. The need of accurate and complete data for DN and DP yields and time characteristics of actinides was the motivation for an experimental campaign, started in 2004. In this paper, the experimental setup and the data analysis method will be presented and the modeling work will be described. Experimental results for DN and DP characteristics will be compared to calculations in the case of photofission of 232Th, 235,238U, and 237Np. (authors)

  7. Mass asymmetry dependence of fusion time-scales in 11B+237Np and 12C, 16O, 19F+232Th reactions in a dynamical trajectory model

    Dynamical trajectory calculations were carried out for the reactions of 11B+237Np and 12C, 16O and 19F+232Th, having mass asymmetries on either side of the Businaro-Gallone critical mass asymmetry αBG, in order to examine the mass asymmetry dependence of fusion reactions in these systems. The compound nucleus formation times were calculated as a function of the partial wave of the reaction for all the systems. This study brings out that for systems with αBG, the formation times are significantly larger than for α>αBG, which is caused by the dynamical effects involved in the large scale shape changes taking place in the fusion process as well as due to the interplay between the thermal and the collective motion during the collision process. The calculated time scales are comparable to the experimental values derived from the pre-fission neutron multiplicity measurements. (author). 16 refs., 4 figs., 1 tab

  8. Delayed neutron and delayed photon characteristics from photofission of 232Th, 235,238U, and 237Np with endpoint Bremsstrahlung photons in the giant dipole resonance region

    Doré, D.; Dighe, P. M.; Berthoumieux, E.; Laborie, J.-M.; Ledoux, X.; Macary, V.; Panebianco, S.; Ridikas, D.

    2009-10-01

    A renewed interest in photonuclear reactions was stimulated by applications as radioactive ion beam production, irradiation stations by high energy photons, shielding of electron accelerators, etc. Today, a particular attention is paid to the non-destructive characterization of waste barrels and the detection of nuclear materials, both based on photofission process and the associated delayed neutron (DN) and delayed photon (DP) emissions. The need of accurate and complete data for DN and DP yields and time characteristics of actinides was the motivation for an experimental campaign, started in 2004. In this paper, the experimental setup and the data analysis method will be presented and the modeling work will be described. Experimental results for DN and DP characteristics will be compared to calculations in the case of photofission of 232Th, 235,238U, and 237Np.

  9. Capture and Fission rate of 232-Th, 238-U, 237-Np and 239-Pu from spallation neutrons in a huge block of lead.

    Vlachoudis, Vasilis

    2000-01-01

    The study is centered on the research of the incineration possibility of nuclear waste, by the association of a particle accelerator with a multiplying medium of neutrons, in the project "Energy Amplifier" of C. Rubbia. It consists of the experimental determination of the rates of capture and fission of certain elements (232-Th, 238-U, 237-Np and 239-Pu) subjected to a fluence of fast spallation neutrons. These neutrons are produced by the interaction of high kinetic energy protons (several GeV) provided by the CERN-PS accelerator, on a large lead solid volume. The measurement techniques used in this work, are based on the activation of elements in the lead volume and the subsequent gamma spectroscopy of the activated elements, and also by the detection of fission fragment traces. The development, of a Monte Carlo code makes it possible, on one hand, to better understand the relevant processes, and on the other hand, to validate the code, by comparison with measurements, for the design and the construction of...

  10. Standard practice for the determination of 237Np, 232Th, 235U and 238U in urine by inductively coupled plasma-Mass spectrometry (ICP-MS) and gamma ray spectrometry.

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This practice covers the separation and preconcentration of neptunium-237 (237Np), thorium-232 (232Th), uranium-235 (235U) and uranium-238 (238U) from urine followed by quantitation using ICP-MS. 1.2 This practice can be used to support routine bioassay programs. The minimum detectable concentrations (MDC) for this method, taking the preconcentration factor into account, are approximately 1E-2Bq for 237Np (0.38ng), 2E-6Bq for 232Th (0.50ng), 4E-5Bq for 235U (0.50ng) and 6E-6Bq for 238U (0.48ng). 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  11. The fission cross sections of 230Th, 232Th, 233U, 234U, 236U, 238U, 237Np, 239Pu and 242Pu relative 235U at 14.74 MeV neutron energy

    The measurement of the fission cross section ratios of nine isotopes relative to 235U at an average neutron energy of 14.74 MeV is described with particular attention to the determination of corrections and to sources of error. The results are compared to ENDF/B-V and to other measurements of the past decade. The ratio of the neutron induced fission cross section for these isotopes to the fission cross section for 235U are: 230Th - 0.290 +- 1.9%; 232Th - 0.191 +- 1.9%; 233U - 1.132 +- 0.7%; 234U - 0.998 +- 1.0%; 236U - 0.791 +- 1.1%; 238U - 0.587 +- 1.1%; 237Np - 1.060 +- 1.4%; 239Pu - 1.152 +- 1.1%; 242Pu - 0.967 +- 1.0%. 40 refs., 11 tabs., 9 figs

  12. Fission Fragment Folding Angle Distributions for the Systems 11B+237Np, 12C+236U, and 16O+232Th in the Energy Range 1.1B<2.1

    Fission fragment folding angle distributions have been measured for the systems 11B+237Np, 12C+236U, and 16O+232Th, populating the same compound nucleus (248Cf) and at similar excitation energies (Ex 45-100 MeV). The full momentum transfer and incomplete momentum transfer fusion-fission components have been separated over the bombarding energy range 1.1c.m/VB 2.1. It is observed that the largest value of the ratio of the transfer fission to the total fission is around 10 to 15% at the highest energy investigated. Over the energy range mentioned above, it is found that the transfer fission corrected fission fragment anisotropies are not significantly different from the values already obtained from the analysis of the total fission data reported earlier and hence the conclusions reached from the inclusive data remain unchanged. The anisotropy data were analyzed for the two cases corresponding to fission events with sizable fission barriers (Bf>T) and with smaller fission barriers (Bf>T). It was interesting to find that the effective moment of inertia (Jeff) values deduced from the latter component were consistent with the values from Sierk prescription used in the former case

  13. In-beam spectroscopy of 231Pa

    Information on energy levels and on E2 and M1 matrix elements in 231Pa has been obtained using conversion-electron and gamma-ray spectroscopy following the 232Th(p, 2p)231Pa reaction and Coulomb excitation of the radioactive target 231Pa by 4He and 32S ions. The results are analyzed in the framework of the rotational model, applied to the rotational band built on the 1/2-[530] Nilsson state whose 3/2- member forms the ground state of this nucleus. The deviations of the level energies from the rigidrotor values can be described by Coriolis couplings. The analysis of the Coulomb-excitation process shows that a constant set of rotational parameters Q0, gR, gK, and b can fairly well account for the measured line intensities. (orig.)

  14. Chemical aspects of 237 Np Moessbauer spectroscopy

    The 237Np Moessbauer effect has been especially useful in studies of neptunium chemistry, by virtue of its excellent resolution and straightforward experimental techniques. Neptunium can have valences from +3 to +7, and a broad range of compounds can be prepared that are analogous to those of other actinide elements. Studies on neptunium compounds, for example, have a ready application to the analogous compounds of uranium and plutonium. The emphasis in this paper will be on the application of the 237Np Moessbauer effect to problems in neptunium chemistry

  15. Neutron-induced fission cross-section of 231 Pa

    Beside the importance of 231 Pa for basic fission studies it is also of interest in the field of future reactor design based on the thorium-uranium fuel cycle. The 232 Th/233 U breeder cycle, where the natural resources of the main fuel thorium are estimated to last for hundred thousands of years, is contemplated to provide 'clean' and almost inexhaustible nuclear energy. Among the first priority isotopes the IAEA had pointed out 231 Pa and 233 Pa. Both are of special interest being intermediate nuclei in the formation of the fissile 233 U from the fertile 232 Th. The latter has been investigated in the recent past in great detail. In particular, 231 Pa carry a similar risk as 239 Pu does in the standard uranium-plutonium cycle due to its comparable half-life and radio-toxicity. Despite the wealth of existing experimental data important discrepancies exist, a scenario, which holds for the existing evaluated data files ENDF/B-VI and JENDL-3.3, too. Presently, the neutron-induced fission cross-section of 231 Pa is under investigation at the VdG neutron source at IRMM for incident neutron energies up to 20 MeV. The obtained cross-sections, representing the 3rd and higher chance fission in 233 Pa(n,f) will serve as precise input for the validation of the reaction cross-section calculations performed on 233 Pa up to 20 MeV and the envisaged extension up to 50 MeV. (authors)

  16. Prospection for natural 231Pa in India

    Protactinium-231 (231Pa) occurs in nature as a member of the decay chain of naturally occuring 235U of the 4n+ 3 radioactive series. The expected protactinium concentration in the Jaduguda ore body (with uranium concentration of 0.03-0.06 %) is around 0.2 parts per billion (ppb) and that in monazite ore (uranium concentration 0.3%) is 0.9 ppb. The process at uranium ore processing plant at Jaduguda was studied. 231Pa content in samples from the process streams of the plant was determined. The gamma ray spectrometry method was chosen and standardised in our laboratory to detect and measure 231Pa in parts per billion levels in these samples. A concentrated source of protactinium could not be found among the assessed streams of Jaduguda uranium plant. The Monazite processing plant at IRE, Aluva was then studied. From the known chemistry of protactinium, the possible distribution of the 231Pa was guessed at. Accordingly, the process streams of IRE process plant were selected to prospect for 231Pa and determine the fractionation of protactinium. For analysis of 231Pa, the thorium bearing samples were chemically treated to remove the thorium daughter products, which interfere in gamma spectrometry. This report describes the planning for prospecting, sample selection, the standardisation of the analysis procedure for determination of 231Pa content, and the analysis results. The 231Pa content in various streams of Indian Rare Earths plant was found in the range 0.2 -6.5 ppb. Some of the streams did not carry any protactinium. The fractionation of 231Pa in the various streams of the plant and the selection of source for recovery of protactinium are discussed in detail. (author)

  17. Irradiation studies of 231Pa in DHRUVA reactor for preparation of 232U

    In this paper, identification of the potential source of 231Pa, various stages of its recovery and the sample of 231Pa supplied for trial irradiation are described. For producing 232U, irradiation work is proposed in different stages of irradiation. Various trial irradiations and its results are discussed in this paper along with their specific objectives. A computational estimation of conversion efficiency of 231Pa (∼ 10μg) to 232U in DHRUVA reactor, was carried out. The computational result predicted the conversion efficiency and the results of γ-spectroscopy based analysis of the second trial sample matched well. A first level calculation was also carried out to estimate the tolerable quantity of 232Th to keep the concentration of 233U below 5% in the 232U sample. The radioactivity due to the presence of various impurities present in the sample, during the high fluence irradiation, is being estimated. The feasibility of production of the 232U isotope in DHRUVA reactor has thus been established. (author)

  18. Pilot measurements of 237Np in forest litter from Poland

    Described are results and the procedure for a pilot study on 237Np content in forest litter samples from Poland in relation to their plutonium activity. Neptunium was determined by inductively coupled plasma mass spectrometry (ICP-MS) and Pu by alpha spectrometry. Two samples originated from a location with pure global fallout and two others from a place with about 65% of the plutonium from Chernobyl. Plutonium activities were determined twice: at Krakow and in Monaco. The two results were consistent and 239+240Pu activities ranged from about 1 to about 7 Bq/kg dry weight (dw). The chemical recovery for Np was between 27 and 89%. Results for 237Np activity concentrations were between 0.099 ± 0.005 and 2.21 ± 0.076 mBq/kg dw. Observed activity ratios were lower than expected and could be explained by fractionation of Np against Pu in forest litter. (author)

  19. The radiological significance of 237Np in the environment

    Measurements have been made of the concentration of 237Np in tissues taken from sheep, which have grazed on sea-washed marshland on the west Cumbrian coast. The concentrations of 239Pu + 240Pu and 241Am were also determined in the same samples, to enable a comparison to be made of relative uptake of these radionuclides to livestock. Consequently, an assessment has been made of the relative radiological significance of these radionuclides, in terms of the dose received by the public from consuming sheep meat products. The concentrations of the same radionuclides were also measured in soil samples taken from the marsh on which the sheep grazed, to estimate the 237Np available to the sheep, via plant uptake and soil ingestion. (Author)

  20. 232Th, a rigid rotor

    We undertake the present work to treat 232Th with a soft rotor formula used recently by C. Bihari et. al for γ-band and modified by J.B. Gupta et. al. It describes energy in terms of moment of inertia and softness parameter

  1. Determination of 237Np in sediments and sea water

    Compared to other transuranic elements such as Pu and Am present environmental levels of Np are very low. Neptunium nuclides are therefore of little radiological significance in the concentrations found in the environment. In the longer term, however, 237Np will become one of the most important radionuclides remaining in high-level radioactive waste. We have further developed a new method for analysis of neptunium in large samples of soil, sediment and seawater. The samples are measured on alpha detectors and by ICPMS (Inductively coupled plasma mass spectrometry)

  2. Study on adsorption of 237Np on bentonite

    The performance of adsorbing 237Np for bentonite as buffer/backfill material was investigated. The adsorption coefficients of 237Np were determined for three kinds of bentonite under atmosphere and anoxic atmosphere. Further, it was studied that Kd values were affected by pH and CO32-. The results are shown as follows: (1) Distribution coefficients Kd under atmosphere: for mixed-bentonite is 47.3 mL/g, for Mg-bentonite 52.0 mL/g and for Ca-bentonite 42.4 mL/g; and the corresponding Kd under anoxic atmosphere: 89.3 mL/g, 38.8 mL/g and 29.0 mL/g, respectively. (2) When pH was lower than 9.2, Kd of the mixed-bentonite increased with the increase of pH and the maxi-mumt Kd value appeared at pH 9.2. (3) Kd of the mixed-bentonite got lower in high carbonate concentration when the total neptunium concentration was smaller than the solubility of NaNpO2CO3. (author)

  3. 237Np: Oxidation state in vivo and chelation by multidentate catecholat and hydroxypyridinonate ligands

    Chemically, 237Np(V) is as toxic as U(VI), and radiologically, about as toxic as 239Pu. Depending on redox conditions in vivo, 237Np exists as weakly complexing Np(V) (NpO2+) or as Np(IV), which forms complexes as stable as those of Pu(IV). Ten multidentate catecholate (CAM) and hydroxypyridinonate (HOPO) ligands with great affinity for Pu(IV) were compared with CaNa3-DTPA for in vivo chelation of 237Np. Mice were injected intravenously with 237NpO2Cl: those in a kinetic study were killed 1 to 2,880 min; in ligand studies, fed mice were injected intraperitoneally with a ligand 5, 60, or 1,440 min after 237Np(V), mice fasted for 16 h were gastrically intubated with a ligand 3 min after 237Np(V), and all were killed 24 h after ligand administration; tissues and excreta were radioanalyzed. Rapid plasma clearance and urinary excretion of 237Np(V) resemble U(VI); deposition and early retention in skeleton and liver resemble Pu(IV). The x-ray absorption near edge structure spectroscopy (XANES) spectra of femora of 237Np(V)-injected mice, compared with spectra of Np(V) and Np(IV) from reference solids, showed predominantly Np(IV). Significant in vivo 237Np chelation was obtained with all of the HOPO and CAM ligands injected at molar ratio 22; the HOPO ligands reduced 237Np in skeleton, liver, and other soft tissue, on average, to 72, 25, and 25% of control, respectively, while CaNa3-DTPA was ineffective

  4. Measurements of {sup 237}Np secondary neutron spectra

    Kornilov, N.V.

    1997-03-01

    The activities carried out during the first year of the project are summarized. The main problems for Np spectra measurements arise from high intrinsic gamma-ray activity of the sample and admixture of the oxygen and iron nuclei. The inelastically scattered neutrons and the fission neutrons spectra for {sup 237}Np were measured by time-of-flight spectrometer of the IPPE at incident neutron energies {approx_equal}1.5 MeV, and {approx_equal}0.5 MeV. A solid tritium target and a Li-metallic target were used as neutron sources. The neutron scattering on C sample (C(n,n) standard reaction) was measured to normalize the Np data. The experimental data should be simulated by Monte Carlo method to correct the experimental data for oxygen and iron admixture as well as for multiple scattering of the neutrons in the sample. Therefore the response function of the spectrometer, and the neutron energy distribution from the source were investigated in detail. (author)

  5. 231Pa systematics in postglacial volcanic rocks from Iceland

    Turner, Simon; Kokfelt, Thomas; Hoernle, Kaj; Lundstrom, Craig; Hauff, Folkmar

    2016-07-01

    Several recent studies have highlighted the potential of combined 238U-230Th and 235U-231Pa systematics to constrain upwelling rates and the role of recycled mafic lithologies in mantle plume-derived basalts. Accordingly, we present measurements of the 231Pa concentrations from 26 mafic volcanic rocks from Iceland, including off-axis basalts from the Snaefellsnes Peninsula, to complement previously published 238U-230Th-226Ra data. 231Pa concentrations vary from 27 to 624 fg/g and (231Pa/235U) ratios from 1.12 to 2.11 with the exception of one anomalous sample from the Southeast Rift which has a 231Pa deficit with (231Pa/235U) = 0.86. An important new result is that basalts from the Southeast Rift and the Snaefellsnes Peninsula define a trend at relatively low (231Pa/235U) for a given (230Th/238U) ratio. Many of the remaining samples fall in or around the global field for ocean island basalts but those from the Mid-Iceland Belt and the Southwest Rift/Reykjanes Peninsula extend to higher (231Pa/235U) ratios at a given (230Th/238U), similar to mid-ocean ridge basalts. In principle, these lavas could result from melting of peridotite at lower pressures. However, there is no reason to suspect that the Mid-Iceland Belt and the Southwest Rift lavas reflect shallower melting than elsewhere in Iceland. In our preferred model, these lavas reflect melting of garnet peridotite whereas those from the Southeast Rift and the Snaefellsnes Peninsula contain a significant contribution (up to 20%) of melt from garnet pyroxenite. This is consistent with incompatible trace element and radiogenic isotope evidence for recycled oceanic crust in these lavas. There is increasing agreement that the displacement of ocean island basalts to lower (231Pa/235U) ratios at a given (230Th/238U), compared to mid-ocean ridge basalts, reflects the role of recycled mafic lithologies such as garnet pyroxenite as well as higher average pressures of melting. It now seems likely that this interpretation may

  6. Pre-concentration studies of 237Np using sulphonic acid based actinide™ resin

    The absorption studies of the standard 237Np have been performed using actinide™ resin to standardise the selective separation. The supernatant solution was checked for alpha activity of 237Np using scintillation counting technique. It was found that more than 95 % of 237Np was absorbed in the actinide™ resin. The absorbed 237Np from the actinide™ resin was leached out using isopropyl alcohol. The leached out activity of 237Np in the isopropyl alcohol was estimated using same alpha scintillation counting technique and was found to be greater than 95 %. The selective absorption of 237Np resin from the other impurities in actinide™ is helpful in the analytical solution during recycle of fuels as well as in the waste management process. This is very much important because 237Np is one of the long-lived minor actinides produced from the 238U(n, 2n) reaction followed by beta decay. Thus it is useful for the conventional reactor based on natU and fast reactor based on U-Pu fuel. (author)

  7. Status of the Neutron Capture Measurement on 237Np with the DANCE Array at LANSCE

    Neptunium-237 is a major constituent of spent nuclear fuel. Estimates place the amount of 237Np bound for the Yucca Mountain high-level waste repository at 40 metric tons. The Department of Energy's Advanced Fuel Cycle Initiative program is evaluating methods for transmuting the actinide waste that will be generated by future operation of commercial nuclear power plants. The critical parameter that defines the transmutation efficiency of actinide isotopes is the neutron fission-to-capture ratio for the particular isotope in a given neutron spectrum. The calculation of transmutation efficiency therefore requires accurate fission and capture cross sections. Current 237Np evaluations available for transmuter system studies show significant discrepancies in both the fission and capture cross sections in the energy regions of interest. Herein we report on 237Np (n,γ) measurements using the recently commissioned DANCE array

  8. High resolution measurement of the 231Pa(n,f) cross section from 0.4 eV to 12 MeV

    231Pa neutron induced fission is one of the reactions contributing to stop the generation of unwanted quantities of 232U produced along with 233U in a liquid-metal fast breeder reactor using the 232Th/233U breeding cycle. 232U production is troublesome because of its short lifetime and because its decay chain yields to many α particles and γ rays including a 2.61 MeV penetrating γ radiation causing extra shielding problems. Since 231Pa is not listed in ENDF/B-IV and only scarce data of the 231Pa(n,f) cross section, sigmasub(f), are available from ENDF/B-V, a high resolution measurement of sigmasub(f) is mostly desirable to estimate properly the production rate of 232U. In addition to this reactor physics preoccupation, the opportunity was taken to study some fundamental aspects of the fission process, mainly to shed a light on the existence of a shallow third minimum in the fission barrier of 232Pa as calculated by Moeller and Nix

  9. Reliable determination of 237Np in environmental solid samples using 242Pu as a potential tracer

    Qiao, Jixin; Hou, Xiaolin; Roos, Per;

    2011-01-01

    , thereby demonstrating the usefulness of 242Pu as a non-isotopic tracer for 237Np chemical yield monitoring. The on-column separation procedure fosters rapid analysis as required in emergency situations since each individual sample can be handled within 2.5h, and leads to a significant decrease in labor...

  10. A study of the multipolar composition of the electrofission cross section of 237Np

    The electrofission cross section for 237Np was measured over the energy range from 0,6 to 60,0 MeV. The multipolar composition of this cross section was investigated using the virtual photons formalism with three different techniques of analysis: unfolding and two versions of multiple parameter regression. (A.C.A.S.)

  11. Radiochemical determination of 237NP in soil samples contaminated with weapon grade plutonium

    Antón, M. P.; Espinosa, A.; Aragón, A.

    2006-01-01

    The Palomares terrestrial ecosystem (Spain) constitutes a natural laboratory to study transuranics. This scenario is partially contaminated with weapon-grade plutonium since the burnout and fragmentation of two thermonuclear bombs accidentally dropped in 1966. While performing radiometric measurements in the field, the possible presence of 237Np was observed through its 29 keV gamma emission. To accomplish a detailed characterization of the source term in the contaminated area using the isotopic ratios Pu-Am-Np, the radiochemical isolation and quantification by alpha spectrometry of 237Np was initiated. The selected radiochemical procedure involves separation of Np from Am, U and Pu with ionic resins, given that in soil samples from Palomares 239+240Pu levels are several orders of magnitude higher than 237Np. Then neptunium is isolated using TEVA organic resins. After electrodeposition, quantification is performed by alpha spectrometry. Different tests were done with blank solutions spiked with 236Pu and 237Np, solutions resulting from the total dissolution of radioactive particles and soil samples. Results indicate that the optimal sequential radionuclide separation order is Pu-Np, with decontamination percentages obtained with the ionic resins ranging from 98% to 100%. Also, the addition of NaNO2 has proved to be necessary, acting as a stabilizer of Pu-Np valences.

  12. Determination of the 233Pa(n, f) reaction cross section from 0.5 to 10 MeV neutron energy using the transfer reaction 232Th(3He, p)234Pa

    The fission probability distributions of 232,233,234Pa and 231Th have been measured up to an excitation energy of 15 MeV, using the transfer reactions 232Th(3He, t)232Pa, 232Th(3He, d)233Pa, 232Th(3He, p)234Pa and 232Th(3He, 4He)231Th. From these measurements, the neutron induced fission cross sections of 231Pa, 233Pa and 230Th have been determined from the product of the fission probabilities of 232Pa, 233Pa and 231Th respectively with the calculated compound nucleus formation cross sections in the 231Pa+n, 233Pa+n and 230Th+n reactions. The validity of the applied method has been successfully tested with the existing neutron induced fission cross sections of 230Th and 231Pa. Special emphasis is put on the 233Pa(n, f) reaction which is of importance for thorium fueled nuclear reactors. Based on a statistical model analysis of the neutron induced fission cross section as a function of neutron energy, it has been possible to determine the barrier parameters of the 234Pa fissioning nucleus. Cross sections for the compound nucleus inelastic scattering 233Pa(n, n') and radiative capture 233Pa(n, γ) reactions have also been calculated and compared with recent evaluations

  13. Benchmark testing calculations for 232Th

    The cross sections of 232Th from CNDC and JENDL-3.3 were processed with NJOY97.45 code in the ACE format for the continuous-energy Monte Carlo Code MCNP4C. The Keff values and central reaction rates based on CENDL-3.0, JENDL-3.3 and ENDF/B-6.2 were calculated using MCNP4C code for benchmark assembly, and the comparisons with experimental results are given. (author)

  14. Effect of DTPA on concentration ratios of 237Np and 244Cm in vegetative parts of bush bean and barley

    Bush beans (Phaseolus vulgaris L.) and barley (Hordeum vulgare L.) were grown in two different soils (noncalcareous and calcareous) in containers in a glasshouse with 530 pCi/g 237Np or 15040 pCi/g 244Cm mixed into separate containers of the soil. The chelating agent DTPA at 100 μg/g soil was added to one half of the containers. The concentration ratio (C.R.) without DTPA was two orders of magnitude higher for 237Np than for 244Cm by two and three orders of magnitude but had little influence on 237Np. For the calcareous soil with DTPA, 244Cm C.R.'s were greater than those for 237Np. In bush beans both 237Np and 244Cm C.R.'s were higher in primary leaves than in trifoliate leaves which were higher than for stems

  15. Measurement of Delayed Neutron Yields from Thermal Neutron Induced Fission of $^{237}$Np

    Gundorin, N A; Pikelner, L B; Revrova, N V; Salamatin, I M; Smirnov, V I; Zhdanova, K V; Zhuchko, V E

    2005-01-01

    This paper reports about the measurement of delayed neutron yields from a thermal neutron induced fission of $^{237}$Np. The method based on periodic irradiation of the sample in pulsed neutron beam with the subsequent registration of neutrons in intervals between pulses is used in the experiment. The method is realized on the "Isomer-M" installation, located on the channel of the IBR-2 pulsed reactor. A description of the installation and a technique of the experiment are presented, a thorough analysis of background processes is performed, results of measurements are shown in this paper. The value of delayed neutron yields from thermal neutron induced fission of $^{237}$Np obtained in the present investigation is $\

  16. Covalency of Neptunium(IV) organometallics from 237Np Moessbauer spectra

    The isomer shifts in 237Np Moessbauer spectra arise from the shielding of neptunium's 6s orbitals by the inner 5f orbitals. In covalent bonding, ligand contributions to the 5f electron density increase the shielding, and the 237Np isomer shift reflects differences in bond character among covalently bonded ligands. The large difference in isomer shift (3.8 cm/sec) between ionic Np(IV) and Np(III) compounds permits a good determination of ligand bonding differences in Np(IV) organometallic compounds. The Moessbauer spectra for about 20 Np(IV) organometallic compounds, principally cyclopentadienyl (Cp) compounds of the general composition Cp/sub x/Np chi/sub 4-x/ (x = 1,2,3; chi = Cl, BH4, /sup n/Bu, Ph, OR, acac), show both the differences in sigma bonding among the chi ligands, as well as the covalent effect of the Cp ligands

  17. Evaluation of 237Np reaction amount by chemical analysis of neptunium sample irradiated at experiment fast reactor 'JOYO'

    The chemical analysis technique was established to determine the nuclide generated in Neptunium (Np) sample with a high accuracy, to contribute to evaluation of transmutation characteristics of 237Np in the fast reactor. (1) Establishment of Chemical Analysis Technique. The chemical analysis technique containing determination technique of fission amount of 237Np, which was consist of Vanadium (V) of capsule material removal and Neodymium (Nd) recovery at high efficiency, was established with optimization of experimental conditions. Four Np samples irradiated in 'JOYO' were analyzed using this technique. Results were as follows. 237Np were determined with high accuracy (relative error was 2.2% at maximum). Errors of fission amount monitoring nuclides 148Nd were half less than that of 137Cs. Small amount of 236Pu was able to determined. (2) Evaluation of 237Np Reaction Amount. The reaction amount of capture, fission and (n, 2n) reactions were evaluated using analyzed values. Transmutation characteristics of 237Np were evaluated using reaction amount. Evaluated results were as follows. The ratio of capture or fission amount to unirradiated 237Np amount were 6.1 - 25.5 at%, 0.7 - 3.6 at%, respectively. The 237Np (n, 2n) 236mNp reaction amount was 7.0 x 10-6 times of 237Np amount at maximum. The dependences of 237Np reaction amount to neutron energy spectrum were revealed from the fact such as linearity of fission to capture reaction amount ratio against fast neutron ratio in same fuel assembly. (author)

  18. Measurement of the Thermal Neutron Capture Cross section of 237Np for the Study of Nuclear Transmutation

    Full text of publication follows: Accurate nuclear data of minor actinides are required for the study of nuclear transmutation of radioactive wastes. The 237Np is one of the most important minor actinides for this study because of its relatively large abundance in irradiated fuels. However, there are apparent discrepancies between the reported neutron capture cross sections of the 237Np for thermal neutrons. History on the measurements of the neutron capture cross section of 237Np for thermal neutrons is briefly presented first. Recent three data measured by a γ ray spectroscopic method are much smaller than those measured by other methods. To deduce the neutron capture cross section by an activation method with γ ray spectroscopy, the relevant γ-ray emission probabilities are used. These decay data could be an origin of the discrepancies on the neutron capture cross section of 237Np. To examine the hypothesis, we measured the relevant γ-ray emission probabilities of 233Pa and 238Np from the ratio of the emission rate to the activity. The obtained emission probabilities are used to correct the thermal neutron capture cross section of 237Np reported previously. The cross section is also independently determined by irradiating 237Np sample in the research reactor of Kyoto University and counting α rays emitted from 237Np and 238Pu with a Si detector. The measured emission probabilities of 233Pa and 238Np, and the neutron capture cross section of 237Np are compared with others from references. The results of the precise decay data explain the discrepancy on the neutron capture cross section of 237Np. Details of the experiments and results will be presented. (authors)

  19. Electronic and structural properties of some ternary neptunium(VII) oxides from 237Np Moessbauer spectroscopy

    The 60 kev Moessbauer resonance of 237Np has been measured in some complex oxides of heptavalent neptunium. The nature of bonding and the molecular symmetry are discussed on the basis of the isomer shift and quadrupole coupling constant data. The molecular character of the compounds is evidenced by the low Debye temperatures and the strong bond covalency. The quadrupole coupling constant is temperature independent; this reveals the absence of any non-bonding states of f electrons. (authors)

  20. Proton-induced fission on 241Am, 238U and 237Np at intermediate energies

    Deppman, A.; Andrade-II, E.; Guimaraes, V; Karapetyan, G. S.; Balabekyan, A. R.; Demekhina, N. A.

    2013-01-01

    Intermediate energy data of proton-induced fission on 241Am, 238U and 237Np targets were analysed and investigated using the computational simulation code CRISP. Inelastic interactions of protons on heavy nuclei and both symmetric and asymmetric fission are regarded. The fission probabilities are obtained from the CRISP code calculations by means of the Bohr-Wheeler model. The fission cross sections, the fissility and the number of nucleons evaporated by the nuclei, before and after fission, ...

  1. (237)Np(n,f) Cross Section: New Data and Present Status

    Paradela, C; Carrapico, C; Eleftheriadis, C; Leeb, H; Calvino, F; Herrera-Martinez, A; Savvidis, I; Vlachoudis, V; Haas, B; Vannini, G; Le Naour, C; Gramegna, F; Wiescher, M; Pigni, M T; Audouin, L; Mengoni, A; Quesada, J; Becvar, F; Plag, R; Cennini, P; Mosconi, M; Duran, I; Rauscher, T; Couture, A; Capote, R; Sarchiapone, L; Vlastou, R; Domingo-Pardo, C; Dillmann, I; Pavlopoulos, P; Karamanis, D; Krticka, M; Jericha, E; Ferrari, A; Martinez, T; Trubert, D; Oberhummer, H; Karadimos, D; Plompen, A; Isaev, S; Terlizzi, R; Kaeppeler, F; Cortes, G; Cox, J; Voss, F; Pretel, C; Colonna, N; Berthoumieux, E; Vaz, P; Heil, M; Lopes, I; Lampoudis, C; Walter, S; Calviani, M; Gonzalez-Romero, E; Embid-Segura, M; Stephan, C; Igashira, M; Papachristodoulou, C; Aerts, G; Tavora, L; Berthier, B; Rudolf, G; Andrzejewski, J; Villamarin, D; Ferreira-Marques, R; Tain, J L; O'Brien, S; Gunsing, F; Reifarth, R; Perrot, L; Lindote, A; Neves, F; Poch, A; Kerveno, M; Rubbia, C; Koehler, P; Dahlfors, M; Wisshak, K; Salgado, J; Dridi, W; Ventura, A; Andriamonje, S; Assimakopoulos, P; Santos, C; Ferrant, L; Lozano, M; Patronis, N; Chiaveri, E; Guerrero, C; Kadi, Y; Vicente, M C; Praena, J; Baumann, P; Oshima, M; Rullhusen, P; Furman, W; David, S; Marrone, S; Tassan-Got, L; Cano-Ott, D; Pavlix, A; Alvarez-Velarde, F; Massimi, C; Mastinu, P; Pancin, J; Papadopoulos, C; Tagliente, G; Haight, R; Chepel, V; Kossionides, E; Badurek, G; Marganiec, J; Lukic, S; Tarrio, D; Alvarez, H

    2011-01-01

    In this document, we present the final result obtained at the n_TOF experiment; for the neutron-induced fission cross section of the (237)Np, from the fission threshold up to 1 GeV. The method applied to get tins result is briefly discussed. n_TOF data are compared to the last experimental measurements using other TOF facilities or the surrogate method, reported experiments performed with monoenergetic sources and the FISCAL systematic, including a discussion about the existing discrepancies.

  2. New experimental determination of the neutronic resonance parameters of 237Np below 500 eV

    For studies of future nuclear reactors dedicated to nuclear waste transmutation, an improvement of the accuracy of the neutron radiative capture cross section of 237Np appears necessary. In the framework of a collaboration between the Commissariat a l'Energie atomique (CEA) and Institute for Reference Materials and Measurement (IRMM, Geel, Bergium), a new determination of the resonance parameters of 237Np has been performed. Two types of experiments are carried out at GELINA, the IRMM pulsed neutron source, using the time of flight method: a transmission experiment which is related to the neutron total cross section and a capture experiment which gives the neutron radiative capture cross section. The resonance parameters presented in this work are extracted from the transmission data between 0 and 500 eV with the least square code REFIT, using the Reich-Moore formalism. In parallel, the Doppler effect is investigated. The commonly used free gas model appears inadequate below 20 eV for neptunium dioxide at room temperature. By the use of the program DOPUSH, which calculates the Doppler broadening with a harmonic crystal model according to Lamb's theory, we are able to produce abetter fit of the experimental data for the resonances of 237Np in NpO2 at low energy or temperatures. In addition to the resonance parameters, a study of their mean value and distribution is included in this work. (authors)

  3. Measurements of neutron capture cross section of 237Np for fast neutrons

    The neutron capture cross section of 237Np has been measured for fast neutrons supplied at the center of the core in the Yayoi reactor. The activation method was used for the measurement, in which the amount of the product 238Np was determined by γ-ray spectroscopy using a Ge detector. The neutron flux at the center of the core calculated by the Monte Carlo simulation code MCNP was renormalized by using the activity of a gold activation foil irradiated simultaneously. The new convention is proposed in this paper to make possible a definite comparison of the integral measurement by the activation method using fast reactor neutrons with differential measurements using accelerator-based neutrons. 'Representative neutron energy' is defined in the convention at which the cross section deduced by the activation measurement has a high sensitivity. The capture cross section of 237Np corresponding to the representative neutron energy was deduced as 0.80±0.04 b at 214±9 keV from the measured reaction rate and the energy dependence of the cross section in the nuclear data library ENDF/B-VII.0. The deduced cross section of 237Np at the representative neutron energy agrees with the evaluated data of ENDF/B-VII.0, but is 15% higher than that of JENDL-3.3 and 13% higher than that of JENDL/AC-2008. (author)

  4. Neutron data evaluation of 232Th

    Consistent evaluation of 232Th measured data base is performed. Hauser-Feshbach- Moldauer theory, coupled channel model and double-humped fission barrier model are employed. Total, differential scattering, fission, capture and (n,xn) data are consistently reproduced as a major constraint for inelastic scattering cross section estimate. The direct excitation of ground state and higher band levels is calculated within rigid rotator and soft (deformable) rotator model, respectively. Structures evident in measured neutron emission spectra are correlated with excitation of levels of Kπ=0- and Kπ=0+, 2+ bands. Prompt fission neutron spectra data are described. Average resonance parameters are provided, which reproduce evaluated cross sections in the range of 10-150 kev. (author)

  5. New radiochemical methods for determination of 237Np a 241Pu using extraction chromatography (Presentation)

    Thesis was focused on the development of a new methodology for the separation of anthropogenic transuranium radionuclides 237Np a 241Pu from different kinds of matrices. The analytical methods used in this study were based on extraction chromatography and were optimized according to the sample type. The proposed radiochemical procedure is a combination of two algorithms, which represent the separation of radionuclides by using extraction chromatographic sorbents TEVA resin and TRU resin supplied by Eichrom Technologies LLC. 239Np a 237Np were selectively captured on sorbent TEVA resin in oxidation state 4+. TRU resin was used for purification of plutonium fraction from interfering americium radionuclide. 242Pu and 239Np radionuclides as tracers have been used to monitor the radiochemical yields of separation. Before every radiochemical separation tracer radionuclide 239Np was obtained by separation from the parent radionuclide 243Am, which is in radioactive equilibrium to 239Np. The average yield of chemical separation was 69,3% for 239Np at 277 keV energy line and 65,9% at 228 keV energy line. The NPL AH-B08069 (2008) samples which consist of the mixture of alpha-radionuclides were used for the modification and optimization of separation method used for separation of Np and Pu in model samples. This method provided high radiochemical yields of 239,240Pu (95,0 ± 3,5)% and 237Np (87,9 ± 3,0)%.. Reliability of the method was verified by applying our modified separation procedures on reference materials IAEA-375 and IAEA-414 supplied by International Atomic Energy Agency. A good agreement between the results is obtained by this procedure and the certified values were found. Samples of contaminated soils from the area of Nuclear power plant A-1 Jaslovske Bohunice which is stored temporarily before disposal were analyzed using developed separation procedure. Specific activity of investigated radionuclides was determined in these samples. (author)

  6. New radiochemical methods for determination of 237Np a 241Pu using extraction chromatography

    Thesis was focused on the development of a new methodology for the separation of anthropogenic transuranium radionuclides 237Np a 241Pu from different kinds of matrices. The analytical methods used in this study were based on extraction chromatography and were optimized according to the sample type. The proposed radiochemical procedure is a combination of two algorithms, which represent the separation of radionuclides by using extraction chromatographic sorbents TEVA resin and TRU resin supplied by Eichrom Technologies LLC. 239Np a 237Np were selectively captured on sorbent TEVA resin in oxidation state 4+. TRU resin was used for purification of plutonium fraction from interfering americium radionuclide. 242Pu and 239Np radionuclides as tracers have been used to monitor the radiochemical yields of separation. Before every radiochemical separation tracer radionuclide 239Np was obtained by separation from the parent radionuclide 243Am, which is in radioactive equilibrium to 239Np. The average yield of chemical separation was 69,3% for 239Np at 277 keV energy line and 65,9% at 228 keV energy line. The NPL AH-B08069 (2008) samples which consist of the mixture of alpha-radionuclides were used for the modification and optimization of separation method used for separation of Np and Pu in model samples. This method provided high radiochemical yields of 239,240Pu (95,0 ± 3,5)% and 237Np (87,9 ± 3,0)%.. Reliability of the method was verified by applying our modified separation procedures on reference materials IAEA-375 and IAEA-414 supplied by International Atomic Energy Agency. A good agreement between the results is obtained by this procedure and the certified values were found. Samples of contaminated soils from the area of Nuclear power plant A-1 Jaslovske Bohunice which is stored temporarily before disposal were analyzed using developed separation procedure. Specific activity of investigated radionuclides was determined in these samples. (author)

  7. RAPID SEPARATION METHOD FOR 237NP AND PU ISOTOPES IN LARGE SOIL SAMPLES

    Maxwell, S.; Culligan, B.; Noyes, G.

    2010-07-26

    A new rapid method for the determination of {sup 237}Np and Pu isotopes in soil and sediment samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for large soil samples. The new soil method utilizes an acid leaching method, iron/titanium hydroxide precipitation, a lanthanum fluoride soil matrix removal step, and a rapid column separation process with TEVA Resin. The large soil matrix is removed easily and rapidly using this two simple precipitations with high chemical recoveries and effective removal of interferences. Vacuum box technology and rapid flow rates are used to reduce analytical time.

  8. Study of 237Np photonuclear reactions near threshold, induced by gamma rays from thermal neutron capture

    The photodisintegration of 237Np has been studied using monochromatic photons produced by thermal neutron capture in several materials. The partial cross sections σ gamma, sub(f) and σ gamma, sub(n) were measured in the energy interval from 5.43 MeV to 10.83 MeV. Analysing the photofission data according to the liquid drop model, the height (E sub(f)) and the curvature ((h/2π)ω) of the simple fission barrier were determined: E sub(f) = (5.9 +- 0.2) MeV and (h/2π)ω = (0.8 +- 0.4) MeV. For the competition between photoneutron emission and fission (GAMMA sub(n) / GAMMA sub(f) a constant value was found (1.28+- 0.15) in the energy range 6.73 - 10.83 MeV. From this result the following nuclear temperatures for 237Np were extracted on bases of some models of levels density: T = 0.84 +- 0.06 MeV (Fujimoto-Yamaguchi model) and T = 0.60 +- 0.04 MeV (Constant Nuclear temperature model). (Author)

  9. Isomeric ratio and cross section of the 237Np(n, 2n) reaction

    It has been shown that on the basis of the Hauser-Feshbach theory, and taking into account the law of the conservation of moment, the isomer ratio for the reaction 237Np (n, 2n) can be calculated. The indeterminateness of the modeling of the 236Np level scheme, to all appearances, has little effect on the energy dependence of the isomeric ratio. The error in the calculated cross section for the (n, 2n) reaction is determined chiefly by the error in the experimental data on the isomeric ratio and on the cross section for the formation of the short-lived state. Obtaining a correct estimate of the error is made difficult by the scarcity of experimental data on the isomeric ratio. The results of this work can be useful in practical activity when combined with an estimate of the cross sections and the creation of a complete system of neutron cross sections for 237Np. Theoretical estimates of the cross sections can to a significant extent compensate for the scarcity and indeterminateness of the experimental data

  10. Improvement of evaluated neutron nuclear data for 237Np and 241Am

    The nuclear data of 237Np and 241Am that are particularly important among the minor actinides were investigated by comparing JENDL-3.2 with the recent evaluated data and available experimental data. As a result of the study, several defects of JENDL-3.2 data were revealed. They were improved on the basis of experimental data or recent evaluated data. For the both nuclides, main quantities revised in the present work were the resonance parameters, cross sections, angular and energy distributions of secondary neutrons, number of neutrons per fission. The data were given in the neutron energy range from 10-5 eV to 20 MeV, and compiled in the ENDF-6 format. (author)

  11. Study of the excited levels of 233Pa by the 237Np alpha decay

    The excited levels in 233Pa following the 237Np alpha decay have been studied, by performing different experiences to complete available data and supply new information. Thus, two direct alpha spectrum measurement, one alpha-gamma bidimensional coincidence experiment, three gamma-gamma and gamma-X ray coincidences and some other measurements of the gamma spectrum, direct and coincident with alpha-particles have been made. These last experiences have allowed to obviate usual radiochemical separation methods, the 233Pa radioactive descendent interferences being eliminated by means of the coincidence technic. As a result, a primary decay scheme has been elaborated, including 15 new gamma transitions and two new levels, not observed in the most recent works. (Author) 60 refs

  12. 232Th(d,4n)230Pa cross-section measurements at ARRONAX facility

    Full text of publication follows. The ARRONAX cyclotron [Ref.1], acronym for 'Accelerator for Research in Radiochemistry and Oncology at Nantes Atlantique' is a new facility installed in Nantes, France. A dedicated program has been launched on production of innovative radionuclides for PET imaging and for β- and α- targeted radiotherapy using proton or α particle. Since the accelerator is also able to deliver deuteron beams up to 35 MeV, we have reconsidered the possibility to use them to produce medical isotopes. In this study, we have focused on cross section measurements using the stacked-foil technique [Ref. 2] of one isotope dedicated to alpha radio-immunotherapy (α RIT) [Ref.3], 226Th which can be produced through different routes. It's of great interest since it has been found to be a more potent alpha particle emitter for leukemia therapies than Bi213 [Ref.4]. Indeed, the 226Th decay produced a cascade of four α particles with a cumulated energy of 27.7 MeV. An additional interest is the possible use of a radionuclide generator system 230U/226Th. 230U could be produced directly via 231Pa(p, 2n)230U, and indirectly via 230Pa using proton or deuteron beams through 232Th(p, 3n)230Pa → 230U, 232Th(d, 4n)230Pa → 230U. Twelve data sets are published concerning the 230Pa cross section induced by proton [Ref 5], only one by deuteron [Ref.6]. As sometimes deuteron induced reaction gives higher cross section values, it seems interesting to focus our study on their use as projectile on 232Th target to produce 230Pa. Contaminants created during irradiation are also measured since a good optimization of the process is supposed to find the best compromise between production yield and purity of the final product. Our new sets of data are compared with the existing data [Refs.5,6] on other existing production routes and with results given by TALYS code calculations [Ref.7]. References: 1] F. Haddad and al., Eur. J. Med. Mol. Imaging (2008) 35

  13. A comparative study of the carcinogenetic effects of 241Am, 239Pu and 237Np

    In this experiment, 420 wistar rats were used to study the comparative carcinogenetic effects of 241Am, 239Pu and 237Np. These nuclides were injected to animals intravenously, subcutaneously or directly into the lung (Stansen's lung puncture method) in doses of 1.0, 5.0 and 8.5 μCi/kg, respectively. As soluble nitrate, the nuclides were rapidly transfered from the site of injection into the bone and the liver. Osteosarcomas were found in some animals 8 months to one year after intoxication. Diagnosis of osteosarcoma is based on the histopatological examination and X-ray photography. In the Am-poisoned rats the incidence of osteosarcoma is about 31-74%, varied with different doses and different routes of intoxication; in Pu-poisoned rats, the incidence of osteosarcoma is about 55-66%. while in Np-poisoned rats, it is about 36-53%. Primary lung cancers were also found in those animals poisoned by means of Stansen's lung puncture method with the above three nuclides. The incidence of primary lung cancers is about 6% in Am-and Pu-poisoned rats and 13% in Np-poisoned rats. The incidence of metastasis of osteosarcoma in lung is about 25-65% for Am-poisoned rats, 45-55% for Pu-poisoned rats and 41-80% for Np-poisoned rats. The life-span of above poisoned rats was significantly shorter than that of the normal control animals. The chemical weight for 241Am, 239Pu and 237Np in same unit of radioactivity (1.0 μCi) equals to 0.308 μg, 15.9 μg and 1418.7 μg, respectively. For this reason, we have to pay more attention to the chemical mass effect in carcinogenesis of the above three nuclides

  14. DETERMINATION OF 237NP AND PU ISOTOPES IN LARGE SOIL SAMPLES BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    Maxwell, S.

    2010-07-26

    A new method for the determination of {sup 237}Np and Pu isotopes in large soil samples has been developed that provides enhanced uranium removal to facilitate assay by inductively coupled plasma mass spectrometry (ICP-MS). This method allows rapid preconcentration and separation of plutonium and neptunium in large soil samples for the measurement of {sup 237}Np and Pu isotopes by ICP-MS. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via {sup 238}U peak tailing. The method provides enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then transferring Pu to DGA resin for additional purification. The decontamination factor for removal of uranium from plutonium for this method is greater than 1 x 10{sup 6}. Alpha spectrometry can also be applied so that the shorter-lived {sup 238}Pu isotope can be measured successfully. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu and {sup 238}Pu were measured by alpha spectrometry.

  15. Development of ionization technique for measurement of fast neutron induced fission products yields of {sup 237}Np

    Goverdovski, A.A.; Khryachkov, V.A.; Ketlerov, V.V.; Mitrofanov, V.F.; Ostapenko, Yu.B.; Semenova, N.N.; Fomichev, A.N.; Rodina, L.F. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-03-01

    Twin gridded ionization chamber and corresponding software was designed for measurements of masses, kinetic energies and nuclear charges of fission fragments from fast neutron induced fission of {sup 237}Np. The ionization detector design, electronics, data acquisition and processing system and the test results are presented in this paper. (J.P.N.)

  16. Measurement of the fission cross-section ratio for 237Np/235U around 14 MeV neutron energies

    Fission cross-section ratio was determined for 237Np/235U around 14 MeV neutron energies with a back-to-back ionization chamber. Neutrons were produced by a 180 KV accelerator using T(d,n)4He reaction. No significant energy dependence was found in the cross section ratio

  17. 231Pa and 233Pa neutron-induced fission up to 20 MeV

    Consistency of neutron-induced fission cross section data of 231Pa and 233Pa and data extracted from transfer reactions is investigated. Present estimate of 233Pa(n,f) fission cross section is supported by smooth level density parameter systematic, validated in case of 231Pa(n,f) data description up to En=20 MeV. The fission probabilities of Pa, fissioning in 231,233Pa(n,nf) reactions, are defined by fitting (3He,d) or (3He,t) transfer reaction data

  18. Fission mode analysis of the reaction {sup 237}Np(n,f) - possibilities and perspectives

    Siegler, P. [Joint Research Centre, Geel (Belgium). Geel Establishment

    1996-03-01

    Fission fragment properties for the reaction {sup 237}Np(n,f) have been measured at the Van de Graaff Laboratory of the IRMM. Using a double gridded ionization chamber the mass, kinetic energy and the angular distribution for both fission fragments could be determined simultaneously for an incident neutron energy range from E{sub n}=0.3 MeV upto E{sub n}=5.5 MeV. Complete datasets have been acquired for 13 different neutron energies covering sub barrier fission as well as fission in the plateau region. A detailed analysis of the fragment distributions and the respective momenta has been carried out, checking the coherence against the excitation energy of the compound nucleus. The consideration of multi-modal fission offers an improved possibility for the description of the fragment distributions backed up by theoretical calculations on the basis of the multi-model random-neck rupture model of Brosa, Grossmann and Mueller. The changes of the fission fragment properties under investigation are completely described and an interpretation of the findings is presented. (author)

  19. Update of 233U, 229-232Th and 230-233Pa Fission Data

    transfer reactions. These are pick-up, stripping or inelastic scattering reactions of charged- particle beams with stable actinide targets, which tremendously enhance the scarce neutron- induced fission cross section data base for the Th-Pa chain of nuclei. Consistent description of non-fissile 230,232Th(n,f) neutron-induced and surrogate fission data allows to quantify the consistency of surrogate, ratio surrogate and neutron-induced fission data. That, in turn, would allow to predict the fission cross sections in keV-energy range of fissile 229,231Th target nuclides. A similar approach in case of 231,233Pa(n,f) reactions with a less diverse data base, allows prediction of fissile targets cross sections of 230,232Pa. Unfortunately, even in the newest data library of JENDL-4.0 the consistency of the fissilities for chain of nuclides is not observed, adverse effect on (n, γ) and (n, xn) prediction is unavoidable. In clear-cut cases like 232Th(n,f) and 230Th(n,f), the fission chances partitioning was done in a simplified manner, the relative contributions of (n,f) and (n,xnf) reactions are defined as a phenomenological, non-Hauser-Feshbach, fit to the observed fission cross sections. In the less clear-cut cases of 231Pa(n,f) and 233Pa(n,f), the fission chances contribution prediction is not correlated with the fissilities of A+1-xPa nuclides, emerging in (n,xnf) reactions

  20. Removal of 230Th and 231Pa from the open ocean

    Concentrations of 230Th and 231Pa were measured in particulate matter collected by sediment traps deployed in the Sargasso Sea (Site S2), the north equatorial Atlantic (site E), and the north equatorial Pacific (Site P) as well as in particles collected by in situ filtration at Site E. Concentrations of dissolved Th and Pa were determined by extraction onto manganese dioxide adsorbers at Site P and at a second site in the Sargasso Sea (site D). Dissolved 230Th/231Pa activity ratios were 3-6 at Sites P and D. In contrast, for all sediment trap samples from greater than 2000 m, unsupported 230Th/231Pa ratios were 22-35 (average 29.7). Ratios were lower in particulate matter sampled at shallower depths. Particles filtered at 3600 m and 5000 m at Site E had ratios of 50 and 40. Results show that suspended particulate matter in the open ocean preferentially scavenges Th relative to Pa. Most of the 230Th produced by decay of 234U in the open ocean is removed by adsorption to settling particulate matter. In contrast, less than 50% of the 231Pa produced by decay of 235U is removed from the water column by this mechanism. Mixing processes transport the remainder to other sinks. (orig.)

  1. Flux of 238U and 232Th in Changjiang estuary

    The study of fluxes of the U, Th of Changjiang River into the East China Sea and its adjacent waters is basic work to understanding of U, Th tracer theirselves and their corresponding biogeochemical cycles process in estuaries, coastal. By sampling in the Xuliujing (i.e. the interface between fresh water and sea water) every month, 200 L water was filtered through 0.45μm fabric cartridge to collect particle nuclides. The dissolved nuclides were co-precipitated using Fe(OH)3 and MnO2. The range of 238U activity in water is 2.30-10.32 Bq·m-3, with an average of 5.48±1.19 Bq·m-3; the activity of 232Th is 1.08-2.32 Bq·m-3, with an average of 1.75±0.29 Bq·m-3. Changjiang River conveyed 238U 4.06 x 1012Bq, 232Th 1.54 x 1012 Bq into the estuary every year. Further study of the seasonal variations 238U, 232Th input to the sea, indicating that: the activity of 238U and Changjiang River estuary water flux have a certain degree of negative correlation (R2=0.65, n=12); the main source of 232Th is the weathering of the river. The activity of 232Th is large on the spring and autumn because of strong weathering in Changjiang Basin comparison with other seasons. Compared with the other estuaries in the world, the flux of 238U and 232Th of the Changjiang River estuary is large because of its large fluxes of sediments and runoff in the world. (authors)

  2. New experimental determination of the neutronic resonance parameters of {sup 237}Np below 500 eV; Nouvelle determination experimentale des parametres de resonances neutroniques de {sup 237}Np en dessous de 500 eV

    Gressier, V

    1999-10-01

    For studies of future nuclear reactors dedicated to nuclear waste transmutation, an improvement of the accuracy of the neutron radiative capture cross section of {sup 237}Np appears necessary. In the framework of a collaboration between the Commissariat a l'Energie atomique (CEA) and Institute for Reference Materials and Measurement (IRMM, Geel, Bergium), a new determination of the resonance parameters of {sup 237}Np has been performed. Two types of experiments are carried out at GELINA, the IRMM pulsed neutron source, using the time of flight method: a transmission experiment which is related to the neutron total cross section and a capture experiment which gives the neutron radiative capture cross section. The resonance parameters presented in this work are extracted from the transmission data between 0 and 500 eV with the least square code REFIT, using the Reich-Moore formalism. In parallel, the Doppler effect is investigated. The commonly used free gas model appears inadequate below 20 eV for neptunium dioxide at room temperature. By the use of the program DOPUSH, which calculates the Doppler broadening with a harmonic crystal model according to Lamb's theory, we are able to produce abetter fit of the experimental data for the resonances of {sup 237}Np in NpO{sub 2} at low energy or temperatures. In addition to the resonance parameters, a study of their mean value and distribution is included in this work. (authors)

  3. RAPID DETERMINATION OF 237 NP AND PU ISOTOPES IN WATER BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY

    Maxwell, S.; Jones, V.; Culligan, B.; Nichols, S.; Noyes, G.

    2010-06-23

    A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of {sup 237}Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry; a hybrid approach. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4 to 6 hours, and can also be used for emergency response. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu, {sup 238}Pu, and {sup 239}Pu were measured by alpha spectrometry.

  4. Benchmarking ~(232)Th Evaluations With KBR and Thor Experiments

    2011-01-01

    The n+232Th evaluations from CENDL-3.1, ENDF/B-Ⅶ.0, JENDL-3.3 and JENDL-4.0 were tested with KBR series and THOR benchmark from ICSBEP Handbook. THOR is Plutonium-Metal-Fast (PMF) criticality benchmark reflected with metal thorium.

  5. Evaluation of 232Th for ENDF/B-V

    The evaluation of neutron and gamma ray production cross sections of 232Th from 10-5 eV to 20 MeV is described, and the parts contributed by the author to the evaluation are discussed. All available new data have been included and the procedures used to assess the experimental data and adopt recommended values are described

  6. 231Pa and 233Pa Neutron-Induced Fission Data Analysis

    The 231Pa and 233Pa neutron-induced fission cross-section database is analyzed within the Hauser-Feshbach approach. The consistency of neutron-induced fission cross-section data and data extracted from transfer reactions is investigated. The fission probabilities of Pa, fissioning in 231,233Pa(n,nf) reactions, are defined by fitting (3He,d) or (3He,t) transfer-reaction data. The present estimate of the 233Pa(n,f) fission cross section above the emissive fission threshold is supported by smooth level-density parameter systematics, validated in the case of the 231Pa(n,f) data description up to En =20 MeV

  7. Some spectroscopic properties of fine structures observed near the 231Pa(n,f) fission threshold

    The 231Pa neutron-induced fission cross section from 140 to 400 keV was resolved into finer structures. For some of the fractionated vibrational resonances in this energy region, the assignment of spectroscopic parameters may support evidence for an asymmetrically deformed third minimum in the 232Pa fission barrier. Also, for the first time, narrow fission resonances are observed above 1.3 eV exhibiting an average fission width /sub obs/ = 8meV

  8. Fission of 232Th in a spallation neutron field

    Yurevich, V. I.; Nikolaev, V. A.; Yakovlev, R. M.

    2016-03-01

    The spatial distributions of thorium fission reaction rate in a spallation neutron field of thick lead target bombarded by protons or deuterons with energy between 1.0 and 3.7 GeV were measured. Approximately a linear dependence of the thorium fission rate on the beam energy is observed. The mean fission cross section of 232Th ≈ 123 mb and it does not depend on energy and type of the beam particles.

  9. Neutron capture of 232Th in the unresolved resonance region

    The thorium cycle was mentioned in the potential needs of nuclear data for Accelerator Driven Systems (Massimo Salvatores, CEA-DEN/DDIN Cadarache, ND2001, Tsukuba, Japan, J.Nucl.Sci.Tech., S.2, p.4, 2002). A 10% uncertainty on the Th(n,γ) data can produce a 30% uncertainty on the proton current requirement to operate an ADS at the sub-critical level of eff keff ∼0.97. The strong impact of the 232Th(n,γ) data on the performance and safe operation of such systems is also discussed. An analysis of the existing experimental data reveals that the status of the 232Th capture data is far from the requested 2% uncertainty level. Recently 232Th average capture measurements, between 5-200 keV neutron energy, were performed at the FzK Karlsruhe (DE) using a total absorption detector consisting of a BaF crystal ball with 97% efficiency installed at the 3.75 MeV Van de Graaff. The experiments were carried out with two metallic discs of 232Th 0.5 and 1.0 mm thick respectively. The FzK average capture cross-section was measured between 5 - 200 keV neutron energy and the cross-section uncertainties estimated as 2% above 20 keV and 4% at 5 keV. A comparison of these measurements with the ENDF/BVI data files shows a reasonable agreement in the neutron energy range above 15 keV. However, discrepancies of up to 40% at lower neutron energies are observed. The same order of discrepancies is observed when comparing the FzK results with the results obtained by Macklin et al. at ORELA. To clarify these discrepancies we measured at IRMM the average capture cross-section at the GEel LINear Accelerator (GELINA)

  10. Procedures for determination of 239,240Pu, 241Am, 237Np, 234,238U, 228,230,232Th, 99Tc and 210Pb-210Po in environmental material

    Since 1987, the Department of Nuclear Safety Research, Risoe National Laboratory has developed procedures for analysis of low-level amounts of radioactivity in large samples of 200 liters seawater, 10 gram sediment, soil and other environmental materials. These analytical procedures provide high chemical yields, good resolution and excellent decontamination factors for large environmental samples analysed by alpha spectrometry and mass spectrometry (ICPMS). The procedures have been checked through practical analysis work and are used in Norway, the Netherlands, Germany, Spain, France and Denmark. (au)

  11. Uranium age determination: Separation and analysis of 230Th and 231Pa

    In this work we focused on the age determination of uranium materials of different uranium enrichment. The radioactive decay of the uranium isotopes provides a chronometer that is inherent to the material, in particular the mother/daughter pairs 234U/230Th and 235U/231Pa can be advantageously used. Due to the relatively long half-lives of 234U (2.46 · 105 years) and 235U (7.04 · 108 years) only minute amounts of daughter nuclides are growing in, therefore both separation of Th and Pa from uranium must be of high chemical recovery and must afford large decontamination factors. Analytical methods for the age determination of uranium samples using the parent/daughter relations 234U/230Th and 235U/231Pa is demonstrated. Thorium is separated from bulk uranium using extraction chromatography and subsequently quantified using square-spectrometry, thermal ionisation mass spectrometry (TIMS) and inductively coupled mass spectrometry (ICP-MS). Protactinium is separated by highly selective sorption of protactinium to silica gel followed by square-spectrometric quantification. The methods were tested and validated using uranium reference materials of different uranium enrichment and of known ages. The experimental results obtained with both methods were found to agree with the assumed ages of the reference materials within the combined uncertainty of the measurement. The analysis exploiting the parent/daughter pair 235U/231Pa exhibits a slightly larger combined uncertainty and bias than the thorium method but is found valuable in validating the experimental results by means of a second, independent analysis

  12. The rotational bands in the nuclei 229Pa and 231Pa

    Experimental evidence is presented for the similarity between the rotational spectra built on the 1/2-[530] state in 231Pa, where the 3/2- member of the band forms the ground state, and in 229Pa, where this state lies within 20 keV of the ground state. Our findings are in contrast with earlier work invoking octupole deformations in the ground state to account for the different positions of low-lying Nilsson states in the two isotopes. (author)

  13. NKS-Norcmass reference material for analysis of Pu-isotopes and 237Np by mass spectrometry

    The aim of the reference material in the Norcmass-project was to produce a low-level (239Pu) sample of sufficient amount to allow individual laboratories to perform several tests without risk of using up the material. Although there are several reference materials available (eg IAEA) few have 239Pu/240Pu data and almost none have 237Np/239Pu-data. Those who have (eg IAEA-384) have very high concentrations and are not useful for testing analytical methods designed for low-level measurements where a large sample mass may be required. The reference material consist of the top 10cm of 2mm sieved soil pooled together from 12 different Danish locations collected during 2003. The Soil was blended and sieved through 0.6 and finally through a 0.4 mm sieve. A total amount of 17 kg soil was produced. Several aliquots of the material was subject to analysis by alpha spectrometry and ICP-MS. The material contain 239+240Pu at a concentration of 0.24 ± 0.01 mBq/g and a 240Pu/239Pu atom ratio of 0.19 ± 0.006. The ratio 237Np/239Pu was determined to 0.32 ± 0.01. (au)

  14. Emission probabilities of the KX-rays following the decay of 237 Np in equilibrium with 233 Pa

    Following participation in the international EUROMET project No. 416 and after our recent paper, concerning the measurement of the emission probability values of the main gamma-rays of 237 Np in equilibrium with 233 Pa, a complementary work has been done in the frame of the collaboration LNHB-VNIIM-KRI-IFIN (with the support of 'Ministere des Affaires Etrangeres' of France). The purpose was to determine the photon emission probabilities for the KX-rays following the decay of these two nuclides. Two different analysis methods have been used. At first, the KX-rays region was analyzed by fitting Voigt functions according to a least squares procedure, included in 'COLEGRAM' deconvolution code. In the second case, the analysis was performed by using full response functions. Thus, the work allowed the determination of the photon emission probabilities with a relative uncertainty of about 2%. This accurate set of data is useful in calculations related to the atomic level scheme of 237 Np/233 Pa and in X-ray spectrometry based applications. (authors)

  15. Inductively Coupled Plasma Mass Spectrometry For The Determination Of 237Np In Spent Nuclear Fuel Samples By Isotope Dilution Method Using 239Np As A Spike

    A determination method for 237Np in spent nuclear fuel samples was developed using an isotope dilution method with 239Np as a spike. In this method, inductively coupled plasma mass spectrometry (ICP-MS) was taken for the 237Np instead of the previously used alpha spectrometry. 237Np and 239Np were measured by ICP-MS and gamma spectrometry, respectively. The recovery yield of 237Np in synthetic samples was 95.9±9.7% (1S, n=4). The 237Np contents in the spent fuel samples were 0.15, 0.25, and 1.06 μg/mgU and these values were compared with those from ORIGEN-2 code. A fairly good agreement between the measurements (m) and calculations (c) was obtained, giving ratios (m/c) of 0.93, 1.12 and 1.25 for the three PWR spent fuel samples with burnups of 16.7, 19.0, and 55.9 GWd/MtU, respectively

  16. Validation of 232Th evaluated nuclear data through benchmark experiments

    Evaluated nuclear data files for nuclides of the thorium-uranium cycle were released as a result of a coordinated research project of the International Atomic Energy Agency. To validate the data a series of benchmark test cases were analysed, with emphasis on the most important nuclides 232Th and 233U. Remaining nuclides appearing in the benchmarks were taken from the ENDF/B-VII beta-2 library, except for a few sensitivity studies where the data were taken from other sources. The results show marked improvement in the agreement with measurements, much of it coming from the new evaluations. (author)

  17. 232 Th - 233 Pa separation by extraction chromatography

    Thorium and protactinium behavior in extraction chromatography systems is presented, aiming its separation by selective retention of the micro constituent on the column. TBP/alumina, TBP/voltalef UF 300, TOA/alumina and TOA/voltalef UF 300 systems were verified. Column preparation as well the 233 Pa removal conditions were settled. The best 232 Th separation from its irradiation product, 233 Pa, has been achieved by using TBP/voltalef UF 300 system. 233 Pa was selectively retained on column from 10 M HCl solutions and eluted with 3 M HCl. (author)

  18. Fusion hybrids for generation of advanced (231Pa+232U+233U+234U)-fuel in closed (U-Pu-Th)-fuel cycle

    Technology of controlled thermonuclear fusion (CTF) is traditionally regarded as a practically inexhaustible energy source. However, development, mastering, broad deployment of fast breeder reactors and closure of nuclear fuel cycle (NFC) can also extend fuel base of nuclear power industry (NPI) up to practically unlimited scales. Under these conditions, it seems reasonable to introduce into a circle of the CTF-related studies the works directed towards solving some principal problems which can appear in a large-scale NPI in closed NFC. The first challenge is a large scale of operations in NFC back-end that should be reduced by achieving substantially higher fuel burn-up in power nuclear reactors. The use of 231Pa-232Th-232U-233U fuel in light-water reactor (LWR) opens a possibility of principle to reach very high (about 30% HM) or even ultra-high fuel burn-up. The second challenge is a potential unauthorized proliferation of fissionable materials. As is known, a certain remarkable quantity of 232U being introduced into uranium fraction of nuclear fuel can produce a serious barrier against switching the fuel over to non-energy purposes. Involvement of hybrid thermonuclear reactors (HTR) into NPI structure can substantially facilitate resolving these problems. If HTR will be involved into NPI structure, then main HTR mission consists not in energy generation but in production of nuclear fuel with a certain isotope composition. The present paper analyzes some neutron-physical features in production of advanced nuclear fuels in thorium HTR blankets. The obtained results demonstrated that such a nuclear fuel may be characterized by very stable neutron-multiplying properties during full LWR operation cycle and by enhanced proliferation resistance too. The paper evaluates potential benefits from involvement of HTR with thorium blanket into the international closed NFC. (author)

  19. Rapid determination of 237Np in soil samples by multi-collector inductively-coupled plasma mass spectrometry and gamma spectrometry

    A radiochemical procedure is developed for the determination of 237Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. 239Np (milked from 243Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO3 solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 x 2 anion exchange resin. 239Np in the resulting solution is measured with gamma-spectrometry for chemical yield determination while the 237Np is measured with MC-ICP-MS. Measurement results for soil samples are presented together with those for two reference samples. By comparing the determined value with the reference value of the 237Np activity concentration, the feasibility of the procedure was validated. (author)

  20. Mass distribution in 19F induced fission of 232Th

    Formation cross sections of several fission products have been determined using the recoil catcher technique followed by γ-ray spectrometry in 19F induced fission of 232Th at Elab=95 and 112 MeV. The data show significant admixture of fission from compound nuclei formed by complete fusion as well as targetlike nuclei formed by transfer reactions. Mass distributions for both the fissioning systems have been obtained using the systematics of charge distribution in low and medium energy fission. Mass distribution for complete fusion fission is broad Gaussian whereas it is asymmetric for transfer induced fission. At 95 MeV the transfer fission constitutes about 28% of total fission cross section while at 112 MeV it is about 14%, showing that the transfer fission fraction decreases with increasing projectile energy across the barrier. The evaporation residue cross sections of the targetlike nucleus formed in the 232Th (19F, 18O) 233Pa reaction were also measured. The evaporation residue cross sections and the calculated decay probabilities of the targetlike nucleus 233Pa by PACE2 have been used to estimate the fraction of proton and α transfer fission in the total transfer fission cross section. copyright 1996 The American Physical Society

  1. Testing the 231Pa/230Th paleo-circulation proxy: A data versus 2D model comparison

    Variations of the Atlantic Meridional Overturning Circulation (AMOC) are believed to have crucially influenced Earth's climate due to its key role in the inter-hemispheric redistribution of heat and carbon. To assess its past strength, the sedimentary 231Pa/230Th proxy has been developed and improved but also contested due to its sensitivity to other factors beyond ocean circulation. In order to provide a better basis for the understanding of the Atlantic 231Pa/230Th system, and therefore to shed light on the controversy, we compare new measurements of Holocene sediments from the north Brazilian margin to water column data and the output of a two-dimensional scavenging-circulation model, based on modern circulation patterns and reversible scavenging parameters. We show that sedimentary 231Pa/230Th data from one specific area of the Atlantic are in very good agreement with model results suggesting that sedimentary 231Pa/230Th is predominantly driven by the AMOC. Therefore, 231Pa/230Th represents an appropriate method to reconstruct past AMOC at least qualitatively along the western margin. (authors)

  2. Calculation of optical model potential for n+232Th reaction

    Background: Accurate nuclear data are needed for the development of molten salt reactors which use thorium as nuclear fuel. Purpose: We attempt to get an optimum set of optical potential parameters for 232Th with the incident neutron energy from 0.1 MeV to 20 MeV Methods: APMN code which based on optical theory and Hauser-Feshbach theory with width fluctuation correction was used. Steepest descent method was adopted when the code seeks the optimum optical parameters automatically. Results: The comparison between the experimental data and the calculation results before and after adjusting the optical parameters shows that the calculation results after adjusting are in better agreement with the experimental data. This set of parameters could be used for nuclear data calculation. Conclusions: Based on the results it could provide a believable set of optical parameters for the neutron data evaluation. (authors)

  3. Precise measurement and analysis of neutron transmission through 232Th

    Three sets of transmission time spectra through up to eight samples of 232Th have been measured for neutron energies from 6.0 MeV to 0.1 MeV by use of a flight-time technique over 22- and 40-m path lengths, the ORELA pulsed neutron source, and a 1-mm-thick lithium glass detector. The resulting total cross section from 0.1 to 20.0 eV seems to be smaller than that contained in the ENDF/B-V evaluation. Least-squares analysis of the transmissions from 9 to 440 eV using a multilevel Breit-Wigner formalism results in neutron widths consistent with those previously reported. An average radiation width of 25.2 MeV is obtained for 19 low-energy s-wave resonances. 3 figures, 5 tables

  4. 240Pu(n,f), 242Pu(n,f), 237Np(n,f), neutron fission cross sections, Esub(n) = 2.5 MeV

    Measurements of the absolute neutron fission cross section of 240Pu, 242Pu and 237Np have been made at 2.5 MeV using a hybrid detector. The fission events were detected in an ionization chamber (2π) and the neutron flux was determined by a proton recoil telescope and a directional long counter. Our values are compared to previous data

  5. Uranium age determination - Separation and analysis of 230Th and 231Pa

    Full text: In recent years several incidents involving illicit trafficking and smuggling of nuclear material, radioactive sources and radioactively contaminated materials have raised growing public concern about criminal acts involving nuclear materials. Consequently, research efforts in nuclear forensic science have been intensified in order to develop and improve methods for the identification of the nature and origin of seized materials. Information obtained from the analysis of unknown nuclear materials is of key importance in order to aide authorities that are in charge of developing fast and appropriate response action. For the identification of nuclear materials various sample characteristics are of relevance, including isotopic composition, the content of chemical impurities, material properties and the date of production. Information on the production date, respectively the 'age' of nuclear materials, will also be of key importance in other fields of nuclear science, i.e. for the verification of a Fissile Materials Cut-Off Treaty (FMCT) in order to distinguish freshly produced materials from 'old' excess weapons materials. The age of nuclear materials may also be of relevance under a strengthened safeguards regime to reveal clandestine production of weapons usable materials, i.e. the separation of plutonium or production of highly enriched uranium (HEU). The age dating of plutonium samples has been described in detail for bulk samples as well as for particles. In this work we focused on the age determination of uranium materials of different uranium enrichment. The radioactive decay of the uranium isotopes provides a chronometer that is inherent to the material, in particular the mother/daughter pairs 234U/230Th and 235U/231Pa can be advantageously used. Due to the relatively long half-lives of 234U (2.46·105 years) and 235U (7.04·108 years) only minute amounts of daughter nuclides are growing in, therefore both separation of Th and Pa from uranium must

  6. Exposure to radioactive aerosols in mining and milling operations: the importance of 227Ac and 231Pa

    'Full-Text:' 227Ac (half-life of 21.8 y) is the daughter or 231Pa; a beta emitter and parent of a subseries with five short-lived alpha-emitters. 231Pa (half-life of 3.27x104 y) is an alpha-emitter of the actinium series, the decay chain of 235U. As daughters of this uranium isotope they are thought to be unimportant as a radiological hazard, despite the fact that their ALI values for ingestion and inhalation are the lowest of any other radionuclide. Both nuclides can be considered as being in secular equilibrium with uranium in most geological media and so the mass concentration of 231Pa is the same of the 226Ra and that of 227Ac is the same of the 210Pa, to mention only two radionuclides of radiological concern. It is shown in this paper that if 231Pa and 227Ac are considered in the evaluations of dose commitments incurred by inhalation of aerosols in mining and milling operations, the results can be 70% higher than those calculated by the methodology of ICRP Publication 47. (author)

  7. [Uptake of radionuclides from soil to plant and the discovery of 226Ra, 232Th hyperaccumulator].

    Zhang, Zhi-Qiang; Chen, Di-Yun; Song, Gang; Yue, Yu-Mei

    2011-04-01

    11 sorts of plant samples and corresponding soil samples were collected in Conghua and Taishan, Pearl River Delta. The specific activity of 238U, 226Ra, 232Th and 40K of samples were investigated by using HPGe-gamma-ray spectra analysis. The results showed that the average specific activity of 238U, 226Ra, 232Th and 40K in soil samples were 151.8, 146.3, 226.6, 665.5 Bq/kg, which were higher than the average values of China and the world. The concentration of 238U in all sort of plants are very low and most of them are lower than detection limit, while the values of 226Ra, 232Th and 40K were high. The contents of 226Ra and 232Th in Dicranopteris dichotoma were the highest, whose average specific activity is 285.9, 986.2 Bq/kg respectively. The average bioconcentration factors (BFs)of 26Ra, 232Th of Dicranopteris dichotoma were 2.20, 4.23, respectively, the other 10 sort of plants have BFs of 2266Ra, 232Th were in the range of 10(-1)-10(-2). The bioconcentration factors and the translocation factors of 226Ra, 232Th of Dicranopteris dichotoma. were all bigger than 1, so Dicranopteris dichotoma can be defined as hyperaccumulator of 226Ra and 232Th. PMID:21717763

  8. Mass and nuclear charge yields for sup 237 Np(2n sub th ,f) at different fission fragment kinetic energies

    Martinez, G.; Barreau, G.; Sicre, A.; Doan, T.P.; Audouard, P.; Leroux, B. (CEA Centre d' Etudes Nucleaires de Bordeaux-Gradignan, 33 - Gradignan (France)); Arafa, W.; Brissot, R.; Bocquet, J.P. (Grenoble-1 Univ., 38 (France). Inst. des Sciences Nucleaires); Faust, H. (Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)); Koczon, P.; Mutterer, M. (Technische Hochschule Darmstadt (Germany, F.R.). Inst. fuer Kernphysik); Goennenwein, F. (Tuebingen Univ. (Germany, F.R.). Physikalisches Inst.); Asghar, M. (Universite des Sciences et de la Technologie Houari Boumediene, Algiers (Algeria). Inst. de Physique); Quade, U.; Rudolph, K. (Muenchen Univ. (Germany, F.R.)); Engelhardt, D. (Karlsruhe Univ. (T.H.) (Germany, F.R.)); Piasecki, E. (Warsaw Univ. (Poland))

    1990-09-03

    The recoil mass separator LOHENGRIN of the Laue-Langevin Institute Grenoble has been used to measure for the first time, the yields of light fission fragments from the fissioning system: {sub 93}{sup 239}Np; this odd-Z nucleus is formed after double thermal neutron capture in a {sub 93}{sup 237}Np target. The mass distributions were measured for different kinetic energies between 92 and 115.5 MeV, but the nuclear charge distributions were determined only up to 112 MeV. These distributions are compared to the distributions obtained for the even-even system {sub 94}{sup 240}Pu. At high kinetic energy, the mass distribution shows a prominent peak around mass number A{sub L}=106. These cold fragmentations are discussed in terms of a calculation based on a scission point model extrapolated to the cold fission case. As expected for an odd-Z fissioning nucleus, the nuclear charge distributions do not reveal any odd-even effect. The global neutron odd-even effect is found to be (8.1{plus minus}1.5)%. A simple model has been used to show that most of the neutron odd-even effect results from prompt neutron evaporation from the fragments. (orig.).

  9. Neutron-induced transmutation reactions in 237Np, 238Pu, and 239Pu at the massive natural uranium spallation target

    Transmutation reactions in the 237Np, 238Pu, and 239Pu samples were investigated in the neutron field generated inside a massive (m = 512 kg) natural uranium spallation target. The uranium target assembly QUINTA was irradiated with the deuteron beams of kinetic energy 2, 4, and 8 GeV provided by the Nuclotron accelerator at the Joint Institute for Nuclear Research (JINR) in Dubna. The neutron-induced transmutation of the actinide samples was measured off-line by implementing methods of gamma-ray spectrometry with HPGe detectors. Results of measurement are expressed in the form of both the individual reaction rates and average fission transmutation rates. For the purpose of validation of radiation transport programs, the experimental results were compared with simulations of neutron production and distribution performed by the MCNPX 2.7 and MARS15 codes employing the INCL4-ABLA physics models and LAQGSM event generator, respectively. In general, a good agreement between the experimental and calculated reaction rates was found in the whole interval of provided beam energies

  10. Measurement of transuranic elements, chiefly 237Np (by neutron activation analysis), in the physical and biological compartments of the French shore of the English Channel

    The behaviour of transuranic elements in the marine environment has been studied via both in situ sampling and laboratory tracer experiments. In particular, the radionuclide 237Np was investigated and techniques for its quantitative determination are described. In the field investigations, a preliminary separation of Np from samples was performed prior to neutron activation analysis, with subsequent γ-ray spectrometry of 238Np. In the laboratory studies, 237Np was determined by a radiochemical method followed by α-spectrometry. The results obtained from the in situ study in the English Channel (sea water, seaweed, molluscs) and from laboratory-uptake experiments (water and mussels) are described. Levels of Pu, Am and Np are compared and the characteristics of neptunium transfer to molluscs are discussed. (author)

  11. Emission probabilities of gamma rays from the decay of 233Pa and 238Np, and the thermal neutron capture cross section of 237Np

    In order to determine the thermal neutron capture cross section of 237Np, the relevant γ emission probabilities of the 312-keV γ-ray from the decay of 233Pa and the 984-keV γ-ray from the decay of 238Np are deduced from the ratio of the emission rate to the activity. The emission rate and activity are measured with a Ge detector and a Si detector, respectively. The measured emission probability for 312-keV γ-ray is 41.6±0.9% and that for 984-keV γ-ray is 25.2±0.5%. The emission probabilities are used to correct the thermal neutron capture cross section of 237Np reported previously, and gives 168±6b. The neutron capture cross section is also determined as 169±6b by α-ray spectroscopic method. The measured emission probabilities and capture cross section are compared with others from references. By averaging these values deduced by different methods, the value of 169±4b is recommended as the thermal neutron capture cross section of 237Np for 2,200 m/s neutrons. (author)

  12. Coulex fission of 234U, 235U, 237Np, and 238Np studied within the SOFIA experimental program

    SOFIA (Studies On FIssion with Aladin) is an experimental project which aims at systematically measuring the fission fragments' isotopic yields as well as their total kinetic energy, for a wide variety of fissioning nuclei. The PhD work presented in this dissertation takes part in the SOFIA project, and covers the fission of nuclei in the region of the actinides: 234U, 235U, 237Np and 238Np. The experiment is led at the heavy-ion accelerator GSI in Darmstadt, Germany. This facility provides intense relativistic primary beam of 238U. A fragmentation reaction of the primary beam permits to create a secondary beam of radioactive ions, some of which the fission is studied. The ions of the secondary beam are sorted and identified through the FR-S (Fragment Separator), a high resolution recoil spectrometer which is tuned to select the ions of interest.The selected - fissile - ions then fly further to Cave-C, an experimental area where the fission experiment itself takes place. At the entrance of the cave, the secondary beam is excited by Coulomb interaction when flying through an target; the de-excitation process involves low-energy fission. Both fission fragments fly forward in the laboratory frame, due to the relativistic boost inferred from the fissioning nucleus.A complete recoil spectrometer has been designed and built by the SOFIA collaboration in the path of the fission fragments, around the existing ALADIN magnet. The identification of the fragments is performed by means of energy loss, time of flight and deviation in the magnet measurements. Both fission fragments are fully (in mass and charge) and simultaneously identified.This document reports on the analysis performed for (1) the identification of the fissioning system, (2) the identification of both fission fragments, on an event-by-event basis, and (3) the extraction of fission observables: yields, TKE, total prompt neutron multiplicity. These results, concerning the actinides, are discussed, and the

  13. Sediment 231Pa/230Th as a recorder of the rate of the Atlantic meridional overturning circulation: insights from a 2-D model

    S. E. Allen

    2010-03-01

    Full Text Available A two dimensional scavenging model is used to investigate the patterns of sediment 231Pa/230Th generated by the Atlantic Meridional Overturning Circulation (AMOC and further advance the application of this proxy for ocean paleocirculation studies. The scavenging parameters and the geometry of the overturning circulation cell have been chosen so that the model generates meridional sections of dissolved 230Th and 231Pa consistent with published water column profiles and an additional 12 previously unpublished profiles measured in the North and Equatorial Atlantic. The processes that generate the meridional sections of dissolved and particulate 230Th, dissolved and particulate 231Pa, dissolved and particulate 231Pa/230Th, and sediment 231Pa/230Th are discussed in detail. The results indicate that the relationship between sediment 231Pa/230Th at any given site and the overturning circulation is very complex. They clearly show that constraining past changes in the strength and geometry of the AMOC requires an extensive data set and they suggest strategies to maximize information from a limited number of samples.

  14. Sediment 231Pa/230Th as a recorder of the rate of the Atlantic meridional overturning circulation: insights from a 2-D model

    S. E. Allen

    2009-11-01

    Full Text Available A two dimensional scavenging-circulation model is used to investigate the patterns of sediment 231Pa/230Th generated by the Atlantic Meridional Overturning Circulation (AMOC and further advance the application of this proxy for ocean paleocirculation studies. The scavenging parameters and the geometry of the overturning circulation cell have been chosen so that the model generates meridional sections of dissolved 230Th and 231Pa consistent with published water column profiles and an additional 12 previously unpublished profiles measured in the North and Equatorial Atlantic. The processes that generate the meridional sections of dissolved and particulate 230Th, dissolved and particulate 231Pa, dissolved and particulate 231Pa/230Th, and sediment 231Pa/230Th are discussed in detail. The results indicate that the relationship between sediment 231Pa/230Th at any given site and the overturning circulation is very complex. They clearly show that constraining past changes in the strength and geometry of the AMOC requires an extensive data set and they suggest strategies to maximize information from a limited number of samples.

  15. Measurement at n-TOF of the 237Np(n, γ) and 240Pu(n, γ) cross sections for the transmutation of nuclear waste

    The final design, safety assessment and precise performance analysis of transmutation devices such as Accelerator Driven Systems (ADS) or Fast Critical Reactors, need accurate and reliable nuclear data. The cross sections of 237Np and 240Pu have been measured in 2004 at n-TOF with good accuracy due to a combination of features unique in the world: high instantaneous neutron fluence and excellent energy resolution of the n-TOF facility [1], innovative Data Acquisition System based on flash ADCs and the use of a high performance BaF2 Total Absorption Calorimeter as a detection device. (authors)

  16. Rapid determination of 237Np in soil samples by multi-collector inductively-coupled plasma mass spectrometry and gamma spectrometry

    Yi, Xiaowei; Shi, Yanmei; Xu, Jiang; He, Xiaobing; ZHANG, HAITAO; Lin, Jianfeng

    2013-01-01

    A radiochemical procedure is developed for the determination of 237Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. 239Np (milked from 243Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO3 solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 × 2 anion exchange resin. 239Np in the resu...

  17. The neutron capture cross sections of 237Np(n,γ) and 240Pu(n,γ) and its relevance in the transmutation of nuclear waste

    Neutron capture cross sections of actinides are of great relevance for the Transmutation of Nuclear Waste in Accelerator Driven Systems (ADS) and Generation-IV reactors. The neutron capture cross sections of 237Np and 240Pu in the range of 1 eV to 2 keV were measured at the n-TOF facility with a Total Absorption Calorimeter. The data have been analyzed with the SAMMY code. The corresponding covariance matrices have been generated. The final cross sections are presented and compared to the previously existing ones.The n-TOF 237Np σ(n,γ) is in agreement with the evaluated data files below 300 eV and its is lower by 10 to 15% up to 2 keV. This discrepancy with the evaluated data files is also observed in the capture cross section derived from the transmission measurements of Gressier et al. In the case of the 240Pu σ(n,γ), the n-TOF σ(n,γ) agrees within uncertainties with JENDL-3.3 and JEFF-3.1, except for a group of resonances around 800 eV. Endf/B-VII data are lower than n-TOF and the mentioned evaluations, with differences that increase with neutron energy up to 15-20 per cent

  18. The neutron capture cross sections of {sup 237}Np(n,{gamma}) and {sup 240}Pu(n,{gamma}) and its relevance in the transmutation of nuclear waste

    Guerrero, C.; Abbondanno, U.; Aerts, G.; Alvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapico, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Kappeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krticka, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martinez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P.M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O' Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M.T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J.L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M.C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K

    2008-07-01

    Neutron capture cross sections of actinides are of great relevance for the Transmutation of Nuclear Waste in Accelerator Driven Systems (ADS) and Generation-IV reactors. The neutron capture cross sections of {sup 237}Np and {sup 240}Pu in the range of 1 eV to 2 keV were measured at the n-TOF facility with a Total Absorption Calorimeter. The data have been analyzed with the SAMMY code. The corresponding covariance matrices have been generated. The final cross sections are presented and compared to the previously existing ones.The n-TOF {sup 237}Np {sigma}(n,{gamma}) is in agreement with the evaluated data files below 300 eV and its is lower by 10 to 15% up to 2 keV. This discrepancy with the evaluated data files is also observed in the capture cross section derived from the transmission measurements of Gressier et al. In the case of the {sup 240}Pu {sigma}(n,{gamma}), the n-TOF {sigma}(n,{gamma}) agrees within uncertainties with JENDL-3.3 and JEFF-3.1, except for a group of resonances around 800 eV. Endf/B-VII data are lower than n-TOF and the mentioned evaluations, with differences that increase with neutron energy up to 15-20 per cent.

  19. anti νsub(p) neutron fission of 232Th near threshold

    The average number of prompt neutrons emitted per fission, anti νsub(p), for 232Th(n,f) has been measured between 1.35 and 2.1 MeV. No large maximum in anti νsub(p) at about 1.4 MeV has been seen. The behaviour of anti νsub(p) and of anti Esub(K), the average total fragment kinetic energy, have been calculated using both a double-humped and triple-humped fission potential barrier. Significant disagreement with existing anti Esub(K) data for 232Th(n,f) is observed

  20. Measurement of the 232Th(n,f) subthreshold and near-subthreshold cross section

    A measurement of the 232Th(n,f) cross section for incident neutron energies between 100 eV and 1.6 MeV has been performed at the Oak Ridge National Laboratory electron linear accelerator. The weak subthreshold fission cross section found in this measurement confirms the model of a low first barrier in the triple-humped fission barrier which has been theoretically predicted for the (232Th+n) system. However, the appearance of a series of plateaus in the near-threshold fission cross section region presents a challenge to current barrier calculations in the 233Th compound nucleus

  1. Variation of natural 232Th excretion in non-exposed persons

    Urinary excretion of 232Th was assessed in occupationally non-exposed persons by means of inductively coupled plasma-mass spectrometry (ICP-MS). Measurements were performed in 55 healthy subjects. Mean daily 232Th excretion was 47±26 μBq x d-1 (range 17-121 μBq x d-1). Results obtained showed no statistically significant correlation with age and no differences were found between males and females. The impact on the assessment of intakes by workers is discussed. (author)

  2. 230,232Th in milk, meat, and grain in Korea

    The concentrations of natural radioisotopes 230Th and 232Th in Korean foods were measured by the method of calcium oxalate co-precipitation in addition to the conventional anion-exchange method and alpha spectroscopic measurement. The 230Th concentrations (mBq/kg-fresh) in Korean foods were found to be as follows: milk 0.14-2.45, pork 2.98-8.97, beef 1.94-9.80, chicken 1.22-13.0, rice 0.43-2.35, wheat 0.53-14.4, and soybeans, 8.44-91.6. The 232Th concentrations (mBq/kg-fresh) in Korean foods were found to be as follows: milk 0.01-2.46, pork 0.28-9.32, beef 1.02-5.34, chicken 0.56-4.98, rice 0.32-2.54, wheat 0.53-20.0, and soybeans, 2.30-42.2. The annual internal dose of Th was also estimated. The annual internal dose of 230Th and 232Th in milk was about 0.006 μSv/yr and much lower than that of other countries because of the low intake of milk in Korea compared to other countries. The annual internal dose of 230Th and 232Th in the rice was about 0.043 μSv/yr and highest because rice is the staple food of Koreans. (author)

  3. Fission product yields measurement of 232Th induced by 14.8 MeV neutron

    The relative cumulative yields of 62 fission products were determined using γ-spectrum method for 232Th induced by 14.8 MeV neutron. Using chain yields summation 200% normalization method, 47 chain yields were given, and the data precision is better than 10%. (authors)

  4. Investigation of the (232)Th Nucleus Excitations at the FEL {gamma} - Nucleus Colliders

    Koru, H; Sultansoy, S F; Sarer, B

    2001-01-01

    The physics search potential of the FEL {gamma} - Nucleus colliders is analysed using excitations of the (232)Th nucleus. It is shown that, due to the monochromacity of FEL {gamma} beam and high statistics, proposed colliders will play an important role in the field of "traditional" nuclear physics.

  5. 232Th and 238U neutron emission cross section calculations and analysis of experimental data

    In this study, pre-equilibrium neutron-emission spectra produced by (n,xn) reactions on nuclei 232Th and 238U have been calculated. Angle-integrated cross sections in neutron induced reactions on targets 232Th and 238U have been calculated at the bombarding energies up to 18 MeV. We have investigated multiple pre-equilibrium matrix element constant from internal transition for 232Th (n,xn) neutron emission spectra. In the calculations, the geometry dependent hybrid model and the cascade exciton model including the effects of pre-equilibrium have been used. In addition, we have described how multiple pre-equilibrium emissions can be included in the Feshbach-Kerman-Koonin (FKK) fully quantum-mechanical theory. By analyzing (n,xn) reaction on 232Th and 238U, with the incident energy from 2 Me V to 18 Me V, the importance of multiple pre-equilibrium emission can be seen cleady. All calculated results have been compared with experimental data. The obtained results have been discussed and compared with the available experimental data and found agreement with each other

  6. Transmutation of 129I, 237Np, 238Pu, 239Pu, and 241Am using neutrons produced in target-blanket system `Energy plus Transmutation' by relativistic protons

    J Adam; K Katovsky; A Balabekyan; V G Kalinnikov; M I Krivopustov; H Kumawat; A A Solnyshkin; V I Stegailov; S G Stetsenko; V M Tsoupko-Sitnikov; W Westmeier

    2007-02-01

    Target-blanket facility `Energy + Transmutation' was irradiated by proton beam extracted from the Nuclotron Accelerator in Laboratory of High Energies of Joint Institute for Nuclear Research in Dubna, Russia. Neutrons generated by the spallation reactions of 0.7, 1.0, 1.5 and 2 GeV protons and lead target interact with subcritical uranium blanket. In the neutron field outside the blanket, radioactive iodine, neptunium, plutonium and americium samples were irradiated and transmutation reaction yields (residual nuclei production yields) have been determined using -spectroscopy. Neutron field's energy distribution has also been studied using a set of threshold detectors. Results of transmutation studies of 129I, 237Np, 238Pu, 239Pu and 241Am are presented.

  7. Neutron-induced fission cross section of 237Np in the keV to MeV range at the CERN n_TOF facility

    Diakaki, M.; Karadimos, D.; Vlastou, R.; Kokkoris, M.; Demetriou, P.; Skordis, E.; Tsinganis, A.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; David, S.; Dolfini, R.; Domingo-Pardo, C.; Dorochenko, A.; Dridi, W.; Duran, I.; Eleftheriadis, Ch.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fuji, K.; Furman, W.; Goncalves, I.; Gallino, R.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Ioannidis, K.; Isaev, S.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karamanis, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Kolokolov, D.; Konovalov, V.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Sedysheva, M.; Stamoulis, K.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Voss, F.; Wendler, H.; Wiescher, M.; Wisshak, K.; n TOF Collaboration

    2016-03-01

    The neutron-induced fission cross section of 237Np was experimentally determined at the high-resolution and high-intensity facility n_TOF, at CERN, in the energy range 100 keV to 9 MeV, using the 235U(n ,f ) and 238U(n ,f ) cross section standards below and above 2 MeV, respectively. A fast ionization chamber was used in order to detect the fission fragments from the reactions and the targets were characterized as far as their mass and homogeneity are concerned by means of α spectroscopy and Rutherford backscattering spectroscopy respectively. Theoretical calculations within the Hauser-Feshbach formalism have been performed, employing the empire code, and the model parameters were tuned in order to successfully reproduce the experimental fission cross-sectional data and simultaneously all the competing reaction channels.

  8. Transmutation of 129I and 237Np using spallation neutrons produced by 1.5, 3.7 and 7.4 GeV protons

    Small samples of approximately 1 g of 129I and 237Np, two long-lived radioactive waste nuclides, were exposed to spallation neutron fluences from relatively small metal targets of lead or uranium, surrounded with a paraffin moderator 6 cm thick irradiated with 1.5, 3.7 and 7.4 GeV protons. The (n, γ) transmutation rates have been determined for the two radioactive waste nuclides. Conventional radiochemical La and U sensors and a variety of solid-state nuclear track detectors were irradiated simultaneously with secondary neutrons. The observed secondary neutron fluences appear to be systematically larger, as compared to the calculations with the well-known cascade codes (LAHET from Los Alamos and DCM-CEM from Dubna)

  9. Study of the mass, nuclear charge and kinetic energy distribution of the fission fragments produced in the reaction 237 Np (2n th, f)

    In this work, we report fission fragment mass, energy and charge distributions measured for the fissioning nucleus: 239 Np 146, This odd Z nucleus is formed after double thermal neutron capture on to the 237 Np 144 target nucleus. These measurements were performed at the I.L.L. recoil mass spectrometer ''Lohengrin'' in Grenoble. The fission fragments were registered by an ionisation chamber placed at the focal plane of the spectrometer. The obtained distributions are compared to the 240 Pu 146 fragment mass, energy and charge distributions. They are discussed within the Wilkins' scission-point model. Cold fission has been studied while selecting fragmentations with final kinetic energies close to the maximum energy released in the reaction. These cold fission events are discussed according to a calculation based on the Wilkins' scission-point model extrapolated to the cold fragmentation case. 51 refs

  10. Measurement of 232Th(, ) and 232Th(, 2) cross-sections at neutron energies of 13.5, 15.5 and 17.28 MeV using neutron activation techniques

    Sadhana Mukerji; H Naik; S V Suryanarayana; S Chachara; B S Shivashankar; V Mulik; Rita Crasta; Sudipta Samanta; B K Nayak; A Saxena; S C Sharma; P V Bhagwat; K K Rasheed; R N Jindal; S Ganesan; A K Mohanty; A Goswami; P D Krishnani

    2012-08-01

    The 232Th(, ) reaction cross-section at average neutron energies of 13.5, 15.5 and 17.28 MeV from the 7Li(, ) reaction has been determined for the first time using activation and off-line -ray spectrometric technique. The 232Th(, 2) cross-section at 17.28 MeV neutron energy has also been determined using the same technique. The experimentally determined 232Th(, ) and 232Th(, 2) reaction cross-sections from the present work were compared with the evaluated data of ENDF/BVII and JENDL-4.0 and were found to be in good agreement. The present data, along with literature data in a wide range of neutron energies, were interpreted in terms of competition between 232Th(, ), (, ), (, ) and (, ) reaction channels. The 232Th(, ) and 232Th(, 2) reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were found to be in good agreement with the experimental data from the present work but were slightly higher than the literature data at lower neutron energies.

  11. Measurement of the generation ratio of 233U and the average radiation capture cross section of 232Th with 232ThO2 irradiated by fast neutrons

    Background: Thorium-Uranium cycle plays an important role in the future's power production technology. Nuclear data involved are urgently needed for engineering design and other purposes since there are obvious differences between the existing evaluated data. Macroscopic neutron integral experiment can be used as a good tool to survey the confusion. Purpose: Macroscopic neutron integral experiment based on radioactive method was carried out to measure the generation ratio of 233U nuclide and the average radiation capture cross section of 232Th while a ThO2 sample was irradiated by fast neutrons leakage from a fast critical facility. We expect that these data can be used as a reference for the research of Th-U cycle. Methods: Radiation capture reactions of 232Th nuclides occur when the nuclides are irradiated by neutrons. 233U nuclides will be generated after two cascade decays by emitting beta rays from the activation products, which are 233Th nuclides. The ThO2 sample was prepared as a slice of 20 mm×10 mm from 0.743 36-g ThO2 powders of 99.9% enriched. The neutron flux was measured by activation method which was 4.07x109 cm-2·s-1 at the sample's irradiation position while the facility worked at the power level of 180 watts. The leakage neutrons' energy distribution was calculated by MC method and it is very close to the fission spectrum with the averaged energy of 1.42 MeV. After irradiation and then a period of cooling time the gamma rays emitted from the sample were measured by an HPGe spectrometer which had been pre-calibrated. From these data the activity of 233Pa was calculated and then the generation ratio of 233U and the average radiation capture cross section of 232Th were calculated. The measured average radiation capture cross section was compared with the cross sections calculated based on the ENDFB-VH.1, CENDL-3.1, JENDL-4.0, BROND2.2 databases. Results: The measured generation ratio of 233U was 4.01×10-12 with an uncertainty of 6

  12. 226Ra, 232Th and 40K analysis in water samples from Assiut, Egypt

    The activity concentrations of 226Ra, 232Th and 40K were determined in water samples, using 2”x 2” NaI(Tl) scintillation detector. Water activity ranges from 0.07 to 0.59 Bq L−1 for 226Ra, 0.05 to 0.37 Bq L−1 for 232Th and 3.25 to 8.72 Bq L−1 for 40K with mean values of 2.64, 2.22 and 119.50 Bq L−1, respectively. As far as the measured gamma radionuclides is concerned, the mean annual effective doses for all analyzed samples of water are in the range of 0.02–0.08, 0.03-0.17 and 0.03-0.10 mSv yr-1 for infants, children and adults, respectively, all being lower than the reference level of the committed effective dose recommended by the WHO.

  13. Fractional absorption in gastrointestinal tract of 232Th by ingestion for Chinese man

    Objective: To estimate fractional absorption in gastrointestinal tract (f1) of 232Th by ingestion for the Chinese male adults. Methods: According to f1 calculation method in literature and results of Th concentrations in dietary foods and organ or tissues for the Chinese male adults, obtained in recent years, f1 values were estimated from the median and mean Th concentrations and compared each other. Results: the f1 value from the median and mean Th concentrations was 0.00048 and 0.00028 respectively. Conclusion: The f1 of 232Th by ingestion for the Chinese male adults should be adopted as 0.00048, being lower than estimated result from the world reference concentrations in UNSCEAR 2000 Report, but quite near to the relevant reported value from Asian countries, such as India or Japan, and supporting the latest recommended value 0.0005 by ICRP too

  14. Fission Product Decay Heat Calculations for Neutron Fission of 232Th

    Son, P. N.; Hai, N. X.

    2016-06-01

    Precise information on the decay heat from fission products following times after a fission reaction is necessary for safety designs and operations of nuclear-power reactors, fuel storage, transport flasks, and for spent fuel management and processing. In this study, the timing distributions of fission products' concentrations and their integrated decay heat as function of time following a fast neutron fission reaction of 232Th were exactly calculated by the numerical method with using the DHP code.

  15. Mass distribution in the quasi-mono-energetic neutron-induced fission of 232Th

    The cumulative yields of various fission products in 232Th(n, f) with average neutron energies of 6.35, 8.53 and 10.09 MeV have been determined using an off-line γ -ray spectrometric technique. The neutron beam was produced from the 7Li(p, n) reaction. From the cumulative fission yields, the mass chain yields were obtained by using charge distribution correction of medium energy. The peak-to-valley (P/V) ratio, the average value of light mass (left angle AL right angle), heavy mass (left angle AH right angle) and the average number of neutrons (left angle ν right angle) at the three different neutron energies of the present work and at other energies from the literature in the 232Th(n, f) reaction were obtained from the mass yield data. The present and the existing literature data in the 232Th(n, f) reaction at various excitation energies were compared with similar data in the 238U(n, f) reaction. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect such as shell closure proximity and even-odd effect. The role of standard I and standard II asymmetric mode of fission was discussed. The different types of mass-yield distributions between 232Th(n, f) and 238U(n, f) reactions were explained from different types of the potential energy between the two fissioning systems. The role of excitation energy was also investigated. (orig.)

  16. Distribution of 137Cs, 40K, 238U and 232Th in soils from Northern Venezuela

    More than one hundred undisturbed soil samples form Northern Venezuela and the islands of Margarita and Los Roques have been analyzed for 137Cs, 40K, 238U and 232Th by γ-ray spectroscopy. The specimens were taken from between 5-10 cm below the earth's surface. Thus, they are valid not only for the 137Cs deposition studies but also for the estimation of the natural γ-ray dose from primordial radionuclides that form the terrestrial component. The concentrations of 40K was directly determined from its 1461 keV γ-ray, while those of 137Cs, 238U and 232Th were performed using a γ-ray from one of their daughter radionuclides: the 661 keV γ-ray of 137mBa for 137Cs, the 1760 keV γ-ray of 214Bi for 238U and the 2620 keV γ-ray of 208Tl for 232Th. Finally, the concentration values were compared with those of global estimates. (author) 15 refs.; 4 figs.; 2 tabs

  17. Radiationless transition probabilities in muonic 208Pb, 232Th, and 238U

    The probabilities for non-radiative (n.r.) excitations Pn.r. in the muonic nuclides 208Pb, 232Th, and 238U have been determined for (μ-, γγ)-measurements by comparing the intensities of muonic X-ray transitions in single and coincidence spectra. The value of Pn.r. (3p→1s), measured for the first time, is about 90% for the actinides 232Th and 238U, but only about 8% for 208Pb. The value of Pn.r. (3d→1s) is found to be 10% for 233Th, 13% for 238U, and about 4% for 208Pb. For 208Pb a vanishing strength of the n.r. decay of the 2p-level is found, while for 232Th and for 238U n.r. strengths of about 20% and 26%, respectively, are observed. By regarding two subcomplexes of the 2p→1s transitions leading to different mean excitation energies the n.r. transition probabilities were found to be different for 238U only, 21.6% and 31.1%, respectively. (orig.)

  18. 232Th, 233Pa, and 234U capture cross-section measurements in moderated neutron flux

    The Th-U cycle was studied through the evolution of a 100 μg 232Th sample irradiated in a moderated neutron flux of 8.01014 n/cm2/s, intensity close to that of a thermal molten salt reactor. After 43 days of irradiation and 6 months of cooling, a precise mass spectrometric analysis, using both TIMS and MC-ICP-MS techniques, was performed, according to a rigorous methodology. The measured thorium and uranium isotopic ratios in the final irradiated sample were then compared with integral simulations based on evaluated data; an overall good agreement was seen. Four important thermal neutron-capture cross-sections were also extracted from the measurements, 232Th (7.34±0.21 b), 233Pa (38.34±1.78 b), 234U (106.12±3.34 b), and 235U (98.15±11.24 b). Our 232Th and 235U results confirmed existing values whereas the cross-sections of 233Pa and 234U (both key parameters) have been redefined

  19. Neutron inelastic-scattering cross sections of 232Th, 233U, 235U, 238U, 239Pu and 240Pu

    Differential-neutron-emission cross sections of 232Th, 233U, 235U, 238U, 239Pu and 240Pu are measured between approx. = 1.0 and 3.5 MeV with the angle and magnitude detail needed to provide angle-integrated emission cross sections to approx. 232Th, 233U, 235U and 238U inelastic-scattering values, poor agreement is observed for 240Pu, and a serious discrepancy exists in the case of 239Pu

  20. Experimental study of the neutron induced fission cross-section of 234U, 237Np and 243Am with time-of-flight spectrometry technics

    The current work concentrates on the measurements of the nuclear data needed for solving the problem of transmutation of radiotoxic waste. It includes fission cross-section of 234U in the energy range from thermal to 1 MeV, 237Np and 243Am in the resonance region and average group capture cross-section of 234U and 236U. Almost all of these data are recommended by IAEA as a first priority needs for transmutation problem. Another objective is to obtain the high resolution data of the fission cross-section of the 234U on the fission barrier to confirm the existence of the fine structure, attributed to the vibrational resonances in the third well of the fission barrier. The Dissertation summarizes more, than 10 years of the experiments, performed on the pulsed neutron sources IBR-2 and IBR-30 of Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research (FLNP JINR) in Dubna, Russia; 'Fakel' of Russian Scientific Center 'Kurchatov's Institute' and n-TOF of CERN. The TOF technique was used for neutron energy spectrometry and various kinds of detectors to mark the fission events. The independent measurements of the same isotopes done on different neutron sources and sometimes with different techniques gives strong, self-consistent set of data. (author)

  1. Application of digital signal-processing technique to delayed-neutron yield measurements on thermal-neutron induced fission of 237Np

    The measurement procedure based on the continuous thermal-neutron beam modulation with a mechanical chopper was developed for delayed-neutron yield measurement of the thermal-neutron induced fission of 237Np. The idea of the procedure is similar to that which is widely used in modern communications for the nonauthorized data access prevention. The data is modulated with predefined pattern before transmission to the public network and only the recipient that has the modulation pattern is able to demodulate it upon reception. For the thermal-neutron induced reaction applications, the thermal-neutron beam modulation pattern was used to demodulate the measured delayed-neutron intensity signals on the detector output resulting in nonzero output only for the detector signals correlated with the beam modulation pattern. A comparison of the method with the conventional measurement procedure was provided, and it was demonstrated that the cross-correlation procedure has special features making it superior over the conventional one when the measured value difference from the background is extremely small. Due to strong sensitivity of measurement procedure on the modulation pattern of the neutron beam, one can implement the modulation pattern of specific shape to separate the effect of the thermal part of the beam from the higher energy one in the most confident way in a particular experiment

  2. Excited levels of 238Np from spectroscopic measurements of the 237Np(n,γ)238Np reaction and /sup 242m/Am alpha decay

    The gamma rays and conversion electrons emitted following neutron capture in a 237Np target have been measured by use of the GAMS and BILL spectrometers at Grenoble. Gamma ray and alpha particle measurements of /sup 242m/Am alpha decay (Ge(Li)γ singles, γ-γ coincidences, α singles) have been made at Livermore. The data from these measurements have been combined with earlier measurements (Ionescu 1979, Asaro 1964) to produce a more detailed level scheme for 238Np. Approximately 36 levels have been identified from all of the experimental evidence. The experimentally-observed bandhead energies can be compared with predicted values derived from a simple linear addition of excitation energies observed in neighboring odd-mass nuclei. Values for the Gallagher-Moszkowski splitting of each configurational pair were obtained from theoretical calculations (Piepenbring 1978). We have assigned configurations to ten rotational bands whose bandhead energies range from 0 to 342 keV and which represent all but one of the configurations predicted to occur below 385 keV

  3. Sequential leaching extraction of 239,240Pu, 238Pu, 241Pu, 237Np and 241Am from a mud sample: An intercomparison study

    The transuranics content of a mud sample taken from a nuclear waste storage container was analysed employing two different sequential extraction methods. The following fractions were isolated: (1)Water soluble (2) Readily available (3) Carbonate bound and specifically adsorbed (4) Organically bound (5) Oxide and hydroxides bound and (6) residual. Both methods differ in the reagents employed, the extraction sequence applied as well as the temperature and means of extraction. The 239,240Pu, 238Pu, 237Np and 241Am extracted in each phase were determined using standard radiochemical procedures. 241Pu was analysed through the 241Am in-growth on just one old disk of the residual fraction containing plutonium. Plutonium was mainly associated to organic-oxides fractions (89-92 %). The percentage extracted in each fraction depended on the method and the extraction sequence used. The soluble fraction of plutonium was less than 13%. Neptunium seemed to be the more soluble than the other transuranics (27%) and the americium showed a tendency to be associated to carbonates (30%). (author)

  4. Studies on 232Th and 238U levels in marine algae collected from the coast of Niigata Prefecture

    To evaluate the properties of algae to concentrate radioactive elements, 14 species of algae like Sargassum were collected in the Prefecture and analyzed for their 232Th and 238U levels with Yokogawa HP4500 ICP-MS apparatus. The places of collection included those near the water discharge of an atomic power station. Mean 232Th and 238U levels were found to be 120 and 260 ng/g dry wt, respectively, and Phaeophyta showed more than several times higher 238U level than Chlorophyta and Rhodophyta. There was no clear difference in 232Th levels. No difference between places of collection was observed in Sargassum 232Th or 238U level. Adsorption of 232Th particle to and incorporation of soluble 238U into algae body were suggested. Mean 232Th and 238U radioactivities were found 73 and 510 μBq/g wet wt, respectively, and the respective annual committed effective doses, 0.2 and 0.3 μSv, calculated from those values were confirmed to be enough lower than the annual public dose limit, 1 mSv. (K.H.)

  5. Exploring quasifission characteristics for +232Th34S forming 266Sg

    Prasad, E.; Wakhle, A.; Hinde, D. J.; Williams, E.; Dasgupta, M.; Evers, M.; Luong, D. H.; Mohanto, G.; Simenel, C.; Vo-Phuoc, K.

    2016-02-01

    Background: Fission fragments from heavy ion collisions with actinide nuclei show mass-asymmetric and mass-symmetric components. The relative probabilities of these two components vary rapidly with beam energy with respect to the capture barrier, indicating a strong dependence on the alignment of the deformed nucleus with the partner in the collisions. Purpose: To study the characteristics of the mass-asymmetric quasifission component by reproducing the experimental mass-angle distributions to investigate mass evolution and sticking times. Methods: Fission fragment mass-angle distributions were measured for the +232Th34S reaction. Simulations to match the measurements were made by using a classical phenomenological approach. Mass ratio distributions and angular distributions of the mass-asymmetric quasifission component were simultaneously fit to constrain the free parameters used in the simulation. Results: The mass-asymmetric quasifission component—predominantly originating from tip (axial) collisions with the prolate deformed 232Th —is found to be peaked near A =200 at all energies and center-of-mass angles. A Monte Carlo model using the standard mass equilibration time constant of 5.2 ×10-21 s predicts more symmetric mass splits. Three different hypotheses assuming (i) a mass halt at A =200 , (ii) a slower mass equilibration time, or (iii) a Fermi-type mass drift function reproduced the main experimental features. Conclusions: In tip collisions for the +232Th34S reaction, mass-asymmetric fission with A ˜200 is the dominant outcome. The average sticking time is found to be ˜7 ×10-21 s, independent of the scenario used for mass evolution.

  6. Photo-fission of 232Th and 238U at intermediate energies

    Deppman, A.(Universidade de São Paulo (USP), São Paulo, Brazil); Andrade-II, E.; Guimaraes, V.; Demekhina, N. A.; Karapetyan, G. S.

    2013-01-01

    In this work we present an analysis of the yields of fission fragments induced by bremsstrahlung photons with endpoint energies of 50 and 3500 MeV on 232Th and 238U targets using the simulation code CRISP. A multimodal fission option was added to this code and an extension of the calculation to the properties of the fission products is presented. By dividing the fissioning nuclei according to their fissionability, an approach is introduced which accounts for the contribution of symmetric and ...

  7. Preparation of radionuclide 212Pb by emanation technique of 232Th

    The paper is focused on preparation of radionuclide 212Pb for its further application. 212Pb radioisotope has radiogenic origin of a series of 232Th. The given radionuclide 212Pb (10.6 h) was captured from Th-source on niobium emmanator shims by influence of electric field at a voltage of 310 V. 212Pb was then eluted from the shims to dilute solution of HNO3. 212Pb thus prepared in this way was then applied at radioindicator study of adsorption processes of clay rocks - bentonites.

  8. Nuclear data evaluation for 237Np, 241Am, 242gAm and 242mAm irradiated by neutrons and protons at energies up to 250 MeV

    Evaluation of nuclear data has been performed for 237Np, 241Am, 242gAm and 242mAm. Neutron data were obtained at energies from 20 to 250 MeV and combined with JENDL-3.3 data at 20 MeV. Evaluation of the proton data has been done from 1 to 250 MeV. The coupled channel optical model was used to obtain angular distributions for elastic and inelastic scattering and transmission coefficients. Pre-equilibrium exciton model and Hauser-Feshbach statistical model were used to describe neutron and charged particles emission from excited nuclei. These evaluation is the first work for producing full sets of evaluated file up to 250 MeV for 237Np and Americium isotopes. (author)

  9. Studies of positron electron pair production in {sup 238}U + {sup 232}Th

    Ahmad, I.; Back, B.B.; Betts, R.R. [and others

    1995-08-01

    Following the non-observation of sharp sum-energy lines in our earlier {sup 238}U + {sup 181}Ta measurements, it was decided to pursue measurements of the {sup 238}U + {sup 232}Th system which, in the previously published work, showed the most striking evidence for near-equal-energy back-to-back pairs leading to sharp sum-energy lines. Following the refurbishing of the APEX silicon arrays and extensive tests of the rotating target wheel assembly, a major positron run took place in November 1994. Rolled 1-mg/cm{sub 2} {sup 232}Th targets were bombarded with 5.95-MeV/u {sup 238}U. The target rotation allowed up to 2 pnA of beam to be used without serious deterioration of the targets. Over 300,000 pairs were accumulated, representing an order-of-magnitude improvement in statistics over the previously published results. Preliminary analysis shows no evidence for the sharp lines at a cross section level orders of magnitude below those previously reported. The analysis of these data is currently being completed in preparation for publication.

  10. Determination of specific concentrations of 40K, 238U and 232Th in mineral fertilizer samples

    The use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as 238U, the 232Th, and their descendants, beyond 40K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of 232Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg-1, the values of 238U specific concentrations ranged from 16.0 to 647.7 Bq.Kg-1 and 40K specific concentrations ranged from 19.1 to 12713 Bq.Kg-1. Concentrations of values are consistent with those found in literature. (author)

  11. Radioactive secular equilibrium in 238U and 232Th series in granitoids from Greece

    Granitoid rocks belonging to plutons of Greece, covering a wide range of compositions and rock-types, have been studied for their specific activity (Bq/kg) of 238U and 226Ra from 238U radioactive series and 228Ra and 228Th from 232Th radioactive series by using gamma-ray spectroscopy. Results on the radioactive secular equilibrium of both 238U and 232Th radioactive series are presented by studying the 226Ra/238U and 228Ra/228Th ratios. The majority of the samples are in radioactive secular equilibrium for 226Ra/238U±1σ. However, several samples exhibit 226Ra/238U ratios significantly different from 1. The distortion of the secular equilibrium in the 226Ra–238U isotopic system of those samples has occurred over the last 1 Ma, and can be associated with post-magmatic processes, mainly rock–water interactions. All studied samples have 228Ra/228Th ratios equal to unity ±1σ. Consequently, they can be considered to be in secular equilibrium for the last 40 a. - Highlights: ► Generally, a strong correlation between 238U and 226Ra is obvious. ► Post-magmatic processes caused radioactive disequilibrium in the 238U isotopic system. ► All samples are in radioactive secular equilibrium in the 232Τh isotopic system. ► There is no correlation between mineralogy, texture, colour, age and the isotopic ratios studied

  12. High resolution photofission measurements in 238U and 232Th. Final report

    A novel technique for measuring the photofission cross section with very high photon energy resolution has been developed. The photons are obtained from selected resonances in the (p,γ) reaction on various light nuclei. The photon energy resolution approaches 200 eV in favorable cases. The photon energy spread at each (p,γ) resonance is approx.20 keV on the average. Measurements of the photo-fission cross sections of 232Th and 238U have been carried out in the energy range from 5.8 to 12 MeV. Intermediate structure has been found in both nuclei at excitation energies around 6 MeV. Various properties of this structure, such as average areas of resonances, their spacing, width, and the underlying bakground, as well as the experimental fission probability averaged over the intermediate structure have been found to agree with theoretical predictions based on a double-humped fission barrier. In the case of 232Th, the feature of this barrier, a rather high first hump and a deep secondary well, are quite different from those predicted by current theoretial barrier calculations. 13 refs., 4 figs., 3 tabs

  13. Natural activities of 238U, 232Th and 40K in building materials

    Seven kinds of building materials were analysed for 238U, 232Th and 40K using a direct γ-counting method. The activity concentrations measured for 238U (30-448 Bq kg-1) and 40K (328-7541 Bq kg-1) were greater than the world average activity for soil (25 and 370 Bq kg-1, respectively) for all building materials analysed, while the activity concentrations of 232Th were found to exceed the average of 25 Bq kg-1 (soil) for red-clay brick (51 Bq kg-1) and ceiling asbestos sheet materials (162 Bq kg-1). The calculated Ra equivalent activities (Raeq) for all materials are higher than the world average value for soil (89 Bq kg-1). For red-clay brick and ceiling asbestos, the Raeq values are found to exceed the limit of 370 Bq kg-1, equivalent to a γ-dose of 1.5 mSv yr-1. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Evaluation and improvement of cross section accuracy for most important dosimetry reactions 27Al(n,p), 56Fe(n,p) and 237Np(n,f) including covariance data

    New evaluations of cross sections and their uncertainties for dosimetry reactions 27Al(n,p) , 56Fe(n,p) and 237Np(n,f) have been carried out in the frame work of IAEA Research Contract No. 11372/RB. Data files prepared for this reactions in the ENDF-6 format may be consider as candidates for the new International Reactor Dosimetry File: IRDF-2002. (author)

  15. Redundant 230Th/ 234U/ 238U, 231Pa/ 235U and 14C dating of fossil corals for accurate radiocarbon age calibration

    Chiu, Tzu-Chien; Fairbanks, Richard G.; Mortlock, Richard A.; Cao, Li; Fairbanks, Todd W.; Bloom, Arthur L.

    2006-09-01

    230Th/ 234U/ 238U dating of fossil corals by mass spectrometry is remarkably precise, but some samples exposed to freshwater over thousands of years may gain and/or lose uranium and/or thorium and consequently yield inaccurate ages. Although a δ 234U initial value equivalent to modern seawater and modern corals has been an effective quality control criterion, for samples exposed to freshwater but having δ 234U initial values indistinguishable from modern seawater and modern corals, there remains a need for additional age validation in the most demanding applications such as the 14C calibration (Fairbanks et al., 2005. Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/ 234U/ 238U and 14C dates on pristine corals. Quaternary Science Reviews 24(16-17), 1781-1796). In this paper we enhance screening criteria for fossil corals older than 30,000 years BP in the Fairbanks0805 radiocarbon calibration data set (Fairbanks et al., 2005) by measuring redundant 230Th/ 234U/ 238U and 231Pa/ 235U dates via multi-collector magnetic sector inductively coupled plasma mass spectrometry (MC-MS-ICPMS) using techniques described in Mortlock et al. (2005. 230Th/ 234U/ 238U and 231Pa/ 235U ages from a single fossil coral fragment by multi-collector magnetic-sector inductively coupled plasma mass spectrometry. Geochimica et Cosmochimica Acta 69(3), 649-657.). In our present study, we regard paired 231Pa/ 235U and 230Th/ 234U/ 238U ages concordant when the 231Pa/ 235U age (±2 σ) overlaps with the associated 230Th/ 234U/ 238U age (±2 σ). Out of a representative set of 11 Fairbanks0805 (Fairbanks et al., 2005) radiocarbon calibration coral samples re-measured in this study, nine passed this rigorous check on the accuracy of their 230Th/ 234U/ 238U ages. The concordancy observed between 230Th/ 234U/ 238U and 231Pa/ 235U dates provides convincing evidence to support closed system behavior of these fossil corals and validation of their 230Th/ 234U/ 238U

  16. Spatial variability of initial 230Th/ 232Th in modern Porites from the inshore region of the Great Barrier Reef

    Clark, Tara R.; Zhao, Jian-xin; Feng, Yue-xing; Done, Terry J.; Jupiter, Stacy; Lough, Janice; Pandolfi, John M.

    2012-02-01

    The main limiting factor in obtaining precise and accurate uranium-series (U-series) ages of corals that lived during the last few hundred years is the ability to constrain and correct for initial thorium-230 ( 230Th 0), which is proportionally much higher in younger samples. This is becoming particularly important in palaeoecological research where accurate chronologies, based on the 230Th chronometer, are required to pinpoint changes in coral community structure and the timing of mortality events in recent time (e.g. since European settlement of northern Australia in the 1850s). In this study, thermal ionisation mass spectrometry (TIMS) U-series dating of 43 samples of known ages collected from living Porites spp. from the far northern, central and southern inshore regions of the Great Barrier Reef (GBR) was performed to spatially constrain initial 230Th/ 232Th ( 230Th/ 232Th 0) variability. In these living Porites corals, the majority of 230Th/ 232Th 0 values fell within error of the conservative bulk Earth 230Th/ 232Th atomic value of 4.3 ± 4.3 × 10 -6 (2 σ) generally assumed for 230Th 0 corrections where the primary source is terrestrially derived. However, the results of this study demonstrate that the accuracy of 230Th ages can be further improved by using locally determined 230Th/ 232Th 0 values for correction, supporting the conclusion made by Shen et al. (2008) for the Western Pacific. Despite samples being taken from regions adjacent to contrasting levels of land modification, no significant differences were found in 230Th/ 232Th 0 between regions exposed to varying levels of sediment during river runoff events. Overall, 39 of the total 43 230Th/ 232Th 0 atomic values measured in samples from inshore reefs across the entire region show a normal distribution ranging from 3.5 ± 1.1 to 8.1 ± 1.1 × 10 -6, with a weighted mean of 5.76 ± 0.34 × 10 -6 (2 σ, MSWD = 8.1). Considering the scatter of the data, the weighted mean value with a more

  17. Computational investigation of 99Mo production yield via proton irradiation of natU and 232Th targets

    Accelerators have some advantages such as safety and cheaper operating and decommissioning costs for 99Mo production. Yield theoretical calculation using computational codes can powerfully estimate usefulness of a proposed nuclear reaction for a routine manufacturing. In this work, Monte Carlo-based code was used to compute 99Mo yield in 232Th and natU proton-irradiated targets, as well as maximum applicable beam current. Results showed that the code well agrees with published experimental data. The targets can bear maximum beam current of 30 µA. Targets from 232Th provides higher 99Mo yield. - Highlights: • Accelerators have a number of advantages over nuclear reactors for 99Mo radioisotope production. • Computational yield calculation can powerfully estimate a proposed nuclear reaction usefulness. • Proton-fission induced reactions on 232Th and natU thick targets result in desirable yield of 99Mo. • Deposited heat calculations determines maximum bearable proton current by the targets

  18. Fission fragment angular momentum in the neutron induced fission of 232Th and 232U

    High spin fractions (HSF) of 130,132Sb and 131,133Te have been determined in the neutron induced fission of 232Th and 232U using off-line gamma ray spectrometric technique. From the HSF, fragment angular momenta (Jrms) were deduced using statistical model analysis. From the Jrms values, deformation parameter (β) were deduced and compared with the same in the even-even and odd-even fissioning systems to examine the effect of nuclear structure and the role of odd neutron spin. In all the fissioning systems the effect of shell closure proximity and odd-even effect on Jrms was clearly observed. However, the role of odd neutron spin was not seen in even-odd fissioning systems like the odd-proton spin effect in odd-odd fissioning systems. (author)

  19. Measurement of the probability of 232Th ternary fission induced by fast neutrons

    Results obtained by measuring the energy dependence of the probability of 232Th ternary fission in the region of vibrational resonances are presented. The measurements were performed by using a double ionization chamber with Frisch grids and a CsI(Tl) scintillation detector. The use of digital methods for pulse processing made it possible to obtain highly reliable results. The data analysis reveals that our value of the ternary-fission probability is compatible with existing systematics, which nevertheless need some correction. The results of our measurements unambiguously indicate that local variations in the total kinetic energy of fission fragments in the region of the individual vibrational resonances cannot be explained by corresponding variations in the ternary-fission probability

  20. Evaluation of the 232Th neutron capture cross section above 3 keV

    This memo describes an evaluation of the 232Th neutron capture cross section in the neutron energy range from 3 keV to 20 MeV. Most existing differential measurements are reviewed, and some data are renormalized to current values of the standards. Several experimentally determined sets of average resonance parameters are also discussed. From 3 to 50 keV the evaluated cross section is described by a set of average statistical resonance parameters. Above 50 keV the evaluated capture cross section is a smooth curve which follows the trend of the most recent measurements. The evaluated capture cross section is compared with many measurements and uncertainty estimates are given

  1. Charge and mass distribution in 7Li induced fission of 232Th

    Formation cross sections of about forty fission products have been determined using recoil catcher technique followed by off line gamma-ray spectrometry in 7Li induced fission of 232Th at Elab=41.9, 36.6 and 31.4 MeV. The measured data have been used to deduce charge and mass distributions. Mass distribution is found to be asymmetric at all the three energies. Cross sections of evaporation residues formed in both transfer reactions (232,233,234Pa) as well as in complete fusion (234Np), have also been measured. The measured evaporation residue cross sections and the decay probabilities of target like nuclei (233,234,235Pa) formed in the various transfer reactions, as calculated by PACE2, have been used to estimate the transfer induced fission cross sections. The data indicated that the magnitude of transfer induced fission is very small

  2. Study on the formation of fission isomer via 232Th + α reaction

    The formation of fission isomer through 232Th+α reaction is studied using the distance-recoil method, employing policarbonate MAKROFOL detector. The total isomeric half-life measured has the value T1/2 = 0.23 ± 0.03 ns and an ratio of formation of isomeric fission relative to prompt fission(σi/σp =0.75x10-5). According to the energy of incident particle (Eα = 28 MeV), the cross-sections presented in the literature and the low value found for the total isomeric half-life, we attribute these half-life value to the 234U isomer (even-even nucleus). The results were compared with those existent in the literature (La69, E170, Re70, Wo70, Po70, Br71) for this isomer. (author)

  3. Prompt γ-rays from the Fast Neutron Induced Fission on 235,238U and 232Th

    Lebois, M.; Wilson, J. N.; Halipré, P.; Leniau, B.; Matea, I.; Oberstedt, A.; Oberstedt, S.; Verney, D.

    Preliminary results from the first experiment using the LICORNE neutron source at the IPN Orsay are presented. Prompt fission gamma rays from fast-neutron induced fission of 238U, 232Th and 235U were detected. Thick samples of around 50 g of 238U and 232Th are used for the first part of the experiment. An ionisation chamber containing ∼ 10 mg samples of 238U and 235U to provide a fission trigger is used for the second part of the experiment. Gamma rays have been detected using 17 high efficiency BaF2 detectors and 6 LaBr3 scintillator detectors.

  4. Radioactivity of Natural Nuclides (40K, 238U, 232Th, 226Ra) in Coals from Eastern Yunnan, China

    Xin Wang; Qiyan Feng; Ruoyu Sun; Guijian Liu

    2015-01-01

    The naturally occurring primordial radionuclides in coals might exhibit high radioactivity, and can be exported to the surrounding environment during coal combustion. In this study, nine coal samples were collected from eastern Yunnan coal deposits, China, aiming at characterizing the overall radioactivity of some typical nuclides (i.e., 40K, 238U, 232Th, 226Ra) and assessing their ecological impact. The mean activity concentrations of 238U, 232Th, 40K and 226Ra are 63.86 (17.70–92.30 Bq· kg-...

  5. Assessment of environmental radioactivity (238U, 232Th and 40K) and radiological mapping of Tata Nagar city (Jharkhand), India

    Study on the natural radioactivity concentration levels (238U, 232Th and 40K) in soil samples of Tata Nagar city obtained from seven locations at Tata Nagar city, India was undertaken and the results of the same are reported. In addition, radiological mapping of natural background gamma radiation levels was carried out throughout Tata Nagar city using vehicle based Mobile monitoring technique and the same is presented here. The activity concentrations were assayed and estimated for 238U, 232Th and 40K isotopes in Bq/Kg, using gamma ray spectrometry and the radiation dose rates were estimated. (author)

  6. 238 U, 232 Th and 40 K in wheat flour samples of Iraq markets

    Ali Abid Abojassim

    2015-05-01

    Full Text Available Introduction. Wheat flour is a nutritious type of food that is widely consumed by various age groups in Iraq. This study investigates the presence of long-lived gamma emitters in different type of wheat flour in Iraqi market. Materials and methods. Uranium (238 U, Thorium (232 Th and Potassium (40 K specific activity in (Bq/kg were measured in (12 different types of wheat flours that are available in Iraqi markets. The gamma spectrometry method with a NaI(Tl detector has been used for radiometric measurements. Also in this study we have calculated the internal hazard index, radium equivalent and absorbed dose rate in all samples. Results and discussion. It is found that the specific activity in wheat flour samples were varied from (1.086±0.0866 Bq/kg to (12.532±2.026 Bq/kg with an average (6.6025 Bq/kg for 238 U, For 232 Th From (0.126±0.066 Bq/kg to (4.298±0.388 Bq/kg with an average (1.9465Bq/kg and for 40 K from (41.842±5.875 Bq/kg to (264.729±3.843 Bq/kg with an average (133.097 Bq/kg. Also, it is found that the radium equivalent and the internal hazard index in wheat flour samples ranged from (3.4031 Bq/kg to (35.1523 Bq/kg with an average (19.6346 Bq/kg and from (0.0091 to (0.1219 with an average (0.0708 respectively. Conclusion. This study prove that the natural radioactivity and radiation hazard indices were lower than the safe.

  7. 238 U, 232 Th and 40 K in wheat flour samples of Iraq markets

    A. A.

    2014-09-01

    Full Text Available Introduction. Wheat flour is a nutritious type of food that is widely consumed by various age groups in Iraq. This study investigates the presence of long-lived gamma emitters in different type of wheat flour in Iraqi market. Materials and methods. Uranium ( 238 U, Thorium ( 232 Th and Potassium ( 40 K specific activity in (Bq/kg were measured in (12 different types of wheat flours that are available in Iraqi markets. The gamma spectrometry method with a NaI(Tl detector has been used for radiometric measurements. Also in this study we have calculated the internal hazard index, radium equivalent and absorbed dose rate in all samples. Results and discussion. It is found that the specific activity in wheat flour samples were varied from (1.086±0.0866 Bq/kg to (12.532±2.026 Bq/kg with an average (6.6025 Bq/kg for 238 U, For 232 Th From (0.126±0.066 Bq/kg to (4.298±0.388 Bq/kg with an average (1.9465Bq/kg and for 40 K from (41.842±5.875 Bq/kg to (264.729±3.843 Bq/kg with an average (133.097 Bq/kg. Also, it is found that the radium equivalent and the internal hazard index in wheat flour samples ranged from (3.4031 Bq/kg to (35.1523 Bq/kg with an average (19.6346 Bq/kg and from (0.0091 to (0.1219 with an average (0.0708 respectively. Conclusion. This study prove that the natural radioactivity and radiation hazard indices were lower than the safe.

  8. Measurement of Fragment Mass Distributions in Neutron-induced Fission of 238U and 232Th at Intermediate Energies

    Conceptual analysis of accelerator-driven systems assumes extensive use of nuclear data on neutron-induced reactions at intermediate energies. In particular, information about the fission fragment yields from the 238U(n,f) and 232Th(n,f) reactions is of particular interest at neutron energies from 10 to 200 MeV. However, there is a lack of such data for both 238U and 232Th. Up to now, the intermediate energy measurements have been performed for 238U only, and there are no data for the 232Th(n,f) reaction. The aim of the work is to provide such data. Fission fragment mass distributions for the 232Th(n,f) and 238U(n,f) reactions have been measured for the incident neutron energies 32.8 MeV, 45.3 MeV and 59.9 MeV. The experiments have been performed at the neutron beam facility of the Universite Catholique de Louvain, Belgium. A multi-section Frisch-gridded ionization chamber has been used as a fission fragment detector. The data obtained have been interpreted in terms of the multimodal random neck-rupture model (MMRNRM). (authors)

  9. Measurement of fission products yields in the quasi-mono-energetic neutron-induced fission of 232Th

    Naik, H.; Mukherji, Sadhana; Suryanarayana, S. V.; Jagadeesan, K. C.; Thakare, S. V.; Sharma, S. C.

    2016-08-01

    The cumulative yields of various fission products in the 232Th(n, f) reaction at average neutron energies of 5.42, 7.75, 9.35 and 12.53 MeV have been determined by using an off-line γ-ray spectrometric technique. The neutron beam was produced from the 7Li(p, n) reaction by using the proton energies of 7.8, 12, 16 and 20 MeV. The mass chain yields were obtained from the cumulative fission yields by using the charge distribution correction of medium energy fission. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect. On the other hand, the higher yield around mass number 133-134 and 143-144 as well as their complementary products were explained based on the standard I and standard II asymmetric mode of fission. From the mass yield data, the average value of light mass (), heavy mass (), the average number of neutrons () and the peak-to-valley (P / V) ratios at different neutron energies of present work and literature data were obtained in the 232Th(n, f) reaction. The different parameters of the mass yield distribution in the 232Th(n, f) reaction were compared with the similar data in the 232Th(γ, f) reaction at comparable excitation energy and a surprising difference was observed.

  10. Concentration of 238U and 232Th among constituent minerals of two igneous plutonic rocks exhibiting elevated natural radioactivity levels

    The concentrations of 238U and 232Th of the constituent minerals in two plutonic rock samples, from N. Greece, exhibiting elevated levels of bulk rock natural radioactivity were determined by using LA-ICP-MS. The available data of whole rock 238U and 232Th concentrations were also used. The minerals were separated using a combination of heavy liquids of various densities, shaking table and magnetic separation techniques. The great variation in the concentrations of 238U and 232Th is probably indicative of the different distribution of U and Th within the same rock, as well as to secondary post-magmatic processes that were responsible for the redistribution of U and Th. An estimation of the contribution of each mineral constituent to the natural radioactivity levels of the bulk rock is attempted. Thorite and zircon contribute the most to the whole rock 238U and 232Th content, while the contribution of apatite is moderate. The contribution of the rest of the minerals examined (fluorite, quartz, plagioclase, K-feldspar, amphibole, pyroxene, magnetite and biotite) is not important. (author)

  11. Study of the violent collisions between 63Cu+232Th at 35 MeV/nucleon

    Cibor, J.; Majka, Z.; Kozik, T.; Staszel, P.; Sosin, Z.; Hagel, K.; Li, J.; Lou, L.; Tezkratt, R.; Utley, D.; Wada, R.; Xiao, B.; Natowitz, J. B.

    1997-01-01

    A study of the decay of hot and heavy composite nuclei produced in the violent collisions between 63Cu and 232Th at 35A MeV is presented. The measurement of fission fragment correlations indicates that ~ 70% of the projectile linear momentum can be transferred to the fissioning system. Heavy reaction products were observed at a laboratory angle of θ=6° in coincidence with neutrons, light charged particles, and intermediate mass fragments. The dynamical aspects of the collisions between the projectile and target nuclei were investigated using the computer code CHIMERA which is based upon the molecular dynamics concept. Asymptotic characteristics of the reaction products were confronted with results of calculations of the tandem CHIMERA plus GEMINI codes. The data and model comparisons show that a composite system of mass as high as 275 amu and with an excitation energy ~ 1 GeV is formed in the most violent collisions. Some of the heavy reaction remnants are located on the fragment mass versus velocity plane inside the area where the evaporation residues resulting from the decay of the hot composite system are expected. A high neutron multiplicity associated with these events indicates their origin in the most dissipative events. However, a low cross section for the production of these remnants and the close similarity of their characteristics to the fission fragments do not allow more conclusive statements.

  12. Transfer reaction cross sections from the interactions of 20Ne and 22Ne with 232Th

    A target of 232Th has been bombarded with 114 MeV 22Ne and with 114 MeV and 129 MeV 20Ne beams. Recoiling reaction products were chemically isolated and the cross sections for protactinium, uranium, and neptunium isotopes were determined. The width of the cross section distributions for a given Z and their neutron-richness are the same as those for similar transfers in Ne+ 248Cm reactions. Population of low spin isomeric states is favored in these reactions over population of high spin states. As was seen in reactions with heavier targets, an increase in reaction energy does little to shift the evaporation residues toward neutron deficiency. The implications are that only primary products with little or no excitation energy and angular momentum survive the fission process to become evaporation residues in these systems, and that the production of these nuclides is more controlled by the change in the identity of the projectile than by the corresponding change in the target

  13. Two-photon laser excitation of trapped 232Th+ ions via the 402 nm resonance line

    Herrera-Sancho, O A; Zimmermann, K; Tamm, Chr; Peik, E; Taichenachev, A V; Yudin, V I; Glowacki, P

    2012-01-01

    Experiments on one- and two-photon laser excitation of 232Th+ ions in a radiofrequency ion trap are reported. As the first excitation step, the strongest resonance line at 402 nm from the 6d^2 7s J=3/2 ground state to the 6d7s7p J=5/2 state at 24874 cm^{-1} is driven by radiation from an extended cavity diode laser. Spontaneous decay of the intermediate state populates a number of low-lying metastable states, thus limiting the excited state population and fluorescence signal obtainable with continuous laser excitation. We study the collisional quenching efficiency of helium, argon, and nitrogen buffer gases, and the effect of repumping laser excitation from the three lowest-lying metastable levels. The experimental results are compared with a four-level rate equation model, that allows us to deduce quenching rates for these buffer gases. Using laser radiation at 399 nm for the second step, we demonstrate two-photon excitation to the state at 49960 cm^{-1}, among the highest-lying classified levels of Th+. Thi...

  14. Measurement of the Neutron Capture Cross Sections of $^{233}$U, $^{237}$Np, $^{240,242}$Pu, $^{241,243}$Am and $^{245}$Cm with a Total Absorption Calorimeter at n_TOF

    Beer, H; Wiescher, M; Cox, J; Rapp, W; Embid, M; Dababneh, S

    2002-01-01

    Accurate and reliable neutron capture cross section data for actinides are necessary for the poper design, safety regulation and precise performance assessment of transmutation devices such as Fast Critical Reactors or Accelerator Driven Systems (ADS). The goal of this proposal is the measurement of the neutron capture cross sections of $^{233}$U, $^{237}$Np, $^{240,242}$Pu, $^{241,243}$Am and $^{245}$Cm at n_TOF with an accuracy of 5~\\%. $^{233}$U plays an essential role in the Th fuel cycle, which has been proposed as a safer and cleaner alternative to the U fuel cycle. The capture cross sections of $^{237}$Np,$^{240,242}$Pu, $^{241,243}$Am and $^{245}$Cm play a key role in the design and optimization of a strategy for the Nuclear Waste Transmutation. A high accuracy can be achieved at n_TOF in such measurements due to a combination of features unique in the world: high instantaneous neutron fluence and excellent energy resolution of the facility, innovative Data Acquisition System based on flash ADCs and t...

  15. The nuclear structure of 229Pa from the 231Pa(p,t)229Pa and 230Th(p,2nγ)229Pa reactions

    The level structure of the 229Pa nucleus has been investigated by means of the 231Pa(p,t)229Pa and 230Th(p,2nγ)229Pa reactions. Triton angular-distribution measurements were subjected to a CCBA analysis and combined with the results of in-beam conversion electron and γ-ray spectroscopy to establish a level scheme. Two low-lying bands of opposite parity were observed up to spins (23/2)- and (17/2)+, respectively. Rotational bands built on some 0+ excitations of the even-even core can be assigned. The lowest states of three further low-lying bands are observed. The level scheme is interpreted in terms of an octupole-deformed core with an unpaired proton. From the E1/E2 branching ratio the electric dipole moment can be deduced vertical stroke D0vertical stroke =(0.09 ±0.04) e .fm. ((orig.))

  16. Natural activities of 40K, 238U and 232Th in elephant grass (Pennisetum purpureum) in Ibadan metropolis, Nigeria

    Samples of elephant grass collected at some pasturing farmlands across different locations in Ibadan metropolis were analyzed for their natural radioactivity concentrations due to 40K, 238U and 232Th radionuclides. Radioactivity measurements were carried out using γ-ray spectroscopy. The average radioactivity concentration of 40K was found to be 64.5±8.1 Bq kg-1, 25.7±5.5 Bq kg-1 for 238U and 33.4±3.9 Bq kg-1 for 232Th. The radiological health implication to the population that may result from these values is found to be very low and almost insignificant. No artificial radionuclide, however, was detected in any of the samples, hence, measurements have been taken as representing baseline values of these radionuclides in the grass in the metropolis

  17. Inelastic scattering and nucleon transfer in the system 232Th+206Pb at the Coulomb barrier

    By the experiment performed in the present thesis on the example of the system 232Th+206Pb the onset of the nuclear interaction in the region of the Coulomb barrier was studied at an incident energy of 6.3 MeV/nucleon. In the range of distances of closest approximation 15.5 fm ≤ D ≤ 38.7 fm respectively 28deg ≤ ΘCM ≤ 150deg the Coulomb excitation of the target isotope was observed. The strong absorption for 'small' distances from the reaction channel of the Coulomb excitation is confirmed by the occurrence of transfer reactions. In the studied thorium-lead system the transfer of one and two neutrons could be detected by means of the characteristic γ radiation of the isotopes 230Th and 207,208Pb with a cross section of 500 mb summed over the measurement range. The possibilities of an evaporation of neutrons from highly excited target nuclei, which could also lead to the isotope 230Th and by this influence the measurement of the 2n transfer, was also studied. The contribution of these processes to the transfer could be estimated to less than 5%. For the determination of the excitation energy, at which the transfer takes place, the transfer probabilities experimentally determined as functions of the distance of closest approximation were compared with the barrier-penetration model originally developed for sub-Coulomb transfer. Small effective neutron-binding energies of 0.6-0.8 MeV and by this high excitation energies resulted in contradiction to our model-independent measurement by means of the mean γ multiplicity and mean γ energies. (orig./HSI)

  18. Measurement of 238U, 232Th and 40K in boreholes at Gosa and Lugbe, Abuja, north central Nigeria

    The purpose of this project is to evaluate the suitability of different sites as locations for obtaining underground water for consumption. The analysis of 238U, 232Th and 40K from rock samples from each layer of borehole at a depth of ∼50 m at Site A borehole, S3L1-S3L6 in Gosa and 40 m at Site B borehole, S4L1-S4L5 in Lugbe, Abuja, north central Nigeria is presented. The gamma-ray spectrometry was carried out using a high-purity germanium detector coupled to a computer-based high-resolution multichannel analyzer. The activity concentrations at Site A borehole for 238U have a mean value of 26±3, ranging from 23±2 to 30±3 Bq kg-1, 232Th a mean value of 63±5, ranging from 48±4 to 76±6 Bq kg-1 and 40K a mean value of 573±72, ranging from 437±56 to 821±60 Bq kg-1. The activity concentrations at Site B borehole for 238U have a mean value of 20±2, ranging from 16±2 to 23±2 Bq kg-1, 232Th a mean value of 46±4, ranging from 43±4 to 49±4 Bq kg-1, 40K a mean value of 915±116 and ranging from 817±103 Bq kg-1 to 1011±128 Bq kg-1. It is noted that the higher activity concentrations of 232Th and 238U are found in Site A at Gosa. Site B has lower radioactivity, and it is recommended that both sites are suitable for underground water consumption. (authors)

  19. Determination of Photofission Fragment Characteristics of 234,238U and 232Th in the Barrier Region

    GÖÖK Alf

    2012-01-01

    The photofission of 232Th, 234U and 238U at excitation energies in the barrier region has been studied. The goal has been to extract information on the mass, total kinetic energy (TKE) and angular distributions of the fission fragments. The experiments were performed using bremsstrahlung, produced by an electron beam in a copper radiator at the injector of the Superconducting Darmstadt linear accelerator (S-DALINAC). Mass and TKE distributions were determined by means of the double kinet...

  20. Soil-to-root vegetable transfer factors for 226Ra, 232Th, 40K, and 88Y in Malaysia

    Soil-to-plant transfer factors (TFs) are of fundamental importance in assessing the environmental impact due to the presence of radioactivity in soil and agricultural crops. Tapioca and sweet potato, both root crops, are popular foodstuffs for a significant fraction of the Malaysian population, and result in intake of radionuclides. For the natural field conditions experienced in production of these foodstuffs, TFs and the annual effective dose were evaluated for the natural radionuclides 226Ra, 232Th, 40K, and for the anthropogenic radionuclide 88Y, the latter being a component of fallout. An experimental tapioca field was developed for study of the time dependence of plant uptake. For soil samples from all study locations other than the experimental field, it has been shown that these contain the artificial radionuclide 88Y, although the uptake of 88Y has only been observed in the roots of the plant Manihot esculenta (from which tapioca is derived) grown in mining soil. The estimated TFs for 226Ra and 232Th for tapioca and sweet potato are very much higher than that reported by the IAEA. For all study areas, the annual effective dose from ingestion of tapioca and sweet potato are estimated to be lower than the world average (290 μSv y−1). - Highlights: • Transfer factors of 226Ra, 232Th, 40K, and 88Y radionuclides were estimated for widely consumed root vegetables in Malaysia. • An experimental tapioca field was developed for study of the time dependence of plant uptakes. • The estimated TF values of 226Ra and 232Th for tapioca and sweet potato are higher than the IAEA reported values. • These site-specific TFs are of importance for model derivations for tropical regions

  1. Evaluation of statistical resonance parameters for 232Th in 4 to 41 keV energy region

    An exhaustive compilation of mean resonance parameters for 232Th isotope reported by different experimental groups, evaluators and users is presented. A set of mean resonance parameters is obtained for 232Th for use in reactor calculations by adjusting the p wave strength function as a function of energy region for a broad group structure corresponding to the already evaluated total and partial cross sections recommended in the ENDF/B-IV library in 4 to 41 keV energy region. The difficulties associated with the evaluation of mean resonance parameters for given evaluated cross sections in the unresolved resonance region are highlighted. A brief comparison of the American ENDF/B procedure and the German KEDAK procedure for the processing of the unresolved resonance data is also given. A possibility exists to explain part of the discrepancies between the calculated and the experimentally determined integral parameters to be due to the non-uniqueness of the mean resonance parameters in the unresolved resonance region for the main fissile and fertile nuclides. It appears more satisfying to evaluate the mean resonance data (and hence the self-shielded cross sections) for a given multigroup structure used in reactor calculations unlike the ENDF/B convention. It is further recommended that the thick sample transmission and self-indication measurements be performed for 232Th in order to determine experimentally the self-shielded cross sections in the unresolved resonance region and to support the above mentioned evaluation of mean resonance parameters. (auth.)

  2. Determination of 228Th, 232Th, and228Ra in wild mushroom from a naturally high radioactive region in Brazil

    Mushrooms are fungi which efficiently accumulate radionuclides, as verified by radiochemistry analyses of specimens collected in contaminated areas, specifically after the Chernobyl nuclear accident. Many studies have demonstrated that mushrooms can be used in monitoring of ecosystem contamination and quality. The present paper is part of a broader study conducted in the Pocos de Caldas plateau region in Minas Gerais, Brazil, investigating assimilation of natural Uranium and Thorium radionuclide series by mushrooms. This region has elevated natural radioactivity due to the presence of radiological anomalies of volcanic origin. These anomalies are ore bodies containing Uranium and Thorium, the later being highly predominant. Many researchers have been conducted concerning radionuclide incorporation by agricultural products on the plateau. The present paper aims to determine 232Th, 228Th, and 228Ra radionuclides in wild mushrooms collected at different locations in the plateau region. 228Ra was determined by radiochemical separation using sulphate coprecipitation followed by beta radiometry. 232Th and 228Th were determined using anion exchange resin purification followed by alpha spectrometry. Higher values were obtained to 228Th than to 232Th. This is due to higher 228Ra mobility, which decays to 228Th. The accuracy of the analytical methods employed was evaluated using the reference sample IAEA Soil 327. These methods had high chemical recovery and high sensitivity. It was possible to confirm that mushrooms accumulate radionuclide and so can be used in environmental contamination and quality assessment. (author)

  3. Determination of fission product yields in the 14 MeV photon (Bremsstrahlung) induced fission of 232Th

    The cumulative yields of various fission products in the 232Th(γ,f) with end-point Bremsstrahlung energy of 14 MeV having have been determined using off-line γ-ray spectrometric technique. The end-point Bremsstrahlung energy of 14 MeV was generated by impinging the electron beam on a solid graphite beam dump of the 20 electron LINAC (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany. From the cumulative fission yields, the mass chain yields were obtained by using charge distribution correction of medium energy. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect such as shell closure proximity and even-odd effect. The mass yield distribution in 232Th(γ,f) is triple humped unlike 238U(γ,f), where it is double humped. This different behaviour in between 232Th* and 238U* was explained from the point of different potential energy surfaces between two systems. (author)

  4. Fission product yield distribution in the 12, 14, and 16 MeV bremsstrahlung-induced fission of 232Th

    The absolute cumulative yields of various fission products in the 12, 14, and 16 MeV bremsstrahlung-induced fission of 232Th were determined using a recoil catcher and an off-line γ -ray spectrometric technique using the ELBE electron linac of Helmholtz-Zentrum Dresden-Rossendorf in Dresden, Germany. The mass chain yields were obtained from the absolute cumulative yields by correcting the charge distribution. The peak-to-valley ratio, average light mass (left angle AL right angle) and heavy mass (left angle AH right angle) values, and average number of neutrons (left angle n right angle exp) in the bremsstrahlung-induced fission of 232Th at different excitation energies were obtained from the mass chain yield data. The present study and existing literature data for the 232Th(γ, f) reaction are compared with similar data for the 238U(γ, f) reaction at various excitation energies, and surprisingly different behavior was found in the two fissioning systems. (orig.)

  5. Activity concentrations of 226Ra, 232Th and 40K in brands of fertilisers used in Nigeria

    The activity concentration of naturally occurring radionuclides 40K, 226Ra and 232Th have been measured in different brands of fertiliser samples sold to farmers in retail markets in six commercial cities in southwestern Nigeria. Gamma ray spectroscopy was employed in the measurements of these radionuclides. The results of measurements showed that the average activity concentration of 40K in the nitrogen, phosphorus and potassium fertilisers across the cities varied from 3972.0 ±416.9 to 5089.3 ±111.3 Bq kg-1, 9.9 ±7.3 to 450.6 ±14.3 Bq kg-1 for 226Ra, while for 232Th it varied from less than lower limit of detection to 15.1 ±2.8 Bq kg-1. The activity concentrations of 40K, 226Ra and 232Th in single super phosphate (SSP) fertilisers and phosphate rocks were also determined. However, high activity concentrations of 226Ra were obtained in the SSP fertiliser and phosphate rocks and in particular, two brands of fertilisers from ITL/TAK and F and C companies. The values of the activity concentration of the radionuclides in the brands of fertilisers used in Nigeria are within the range of values reported in several other countries except 40K. (authors)

  6. Investigation of Neutron Spectra and Transmutation of ^{129}I, ^{237}Np and Other Nuclides with 1.5 GeV Protons from the Dubna Nuclotron Using the Electronuclear Setup "Energy plus Transmutation"

    Krivopustov, M I; Balabekyan, A R; Batusov, Yu A; Bielewicz, M; Brandt, R; Chaloun, P; Chultem, D; Dwivedi, K K; Elishev, A F; Fragopoulou, M; Henzl, V; Henzlová, D; Kalinnikov, V G; Kievets, M K; Krása, A; Krizek, F; Kugler, A; Manolopoulou, Metaxia; Mariin, I I; Nourreddine, A; Odoj, R; Pavliouk, A V; Pronskikh, V S; Robotham, H; Siemon, K; Szuta, M; Stegailov, V I; Solnyshkin, A A; Sosnin, A N; Stoulos, S; Tsoupko-Sitnikov, V M; Tumendelger, T; Wojecehowski, A; Wagner, V; Wan, J S; Westmeier, W; Zamani-Valasiadou, M; Kumawat, H; Kumar, V; Zaverioukha, O S; Zhuk, I V

    2004-01-01

    Experiments which are part of the scientific program "Investigations of physical aspects of electronuclear method of energy production and transmutation for radioactive waste of atomic energetics using relativistic beams from the JINR Synchrophasotron/Nuclotron" (project "Energy plus Transmutation") are described. A large lead target surrounded by a four-section uranium blanket with total weight of 206.4 kg natural uranium was irradiated with 1.5 GeV protons from the new cryogenic accelerator Nuclotron. Radiochemical sensors were exposed to the secondary particle fluences inside and on top of the target assembly. Two long-lived radioactive waste of atomic energetics sensors ^{129}I and ^{237}Np (approximately 1 g weight each) and stable nuclides ^{27}Al, ^{59}Co, ^{127}I, ^{139}La, ^{197}Au and ^{209}Bi as well as natural and enriched uranium were used. In addition, various solid state nuclear track detectors and nuclear emulsions were exposed simultaneously. The experimental results confirm the theoretical e...

  7. Measurement of the fission fragment angular distribution for 232Th(n,f) at the CERN n-TOF facility

    Tarrío, D; Audouin, L; Duran, I; Leong, L S; Paradela, C; Altstadt, S; Andrzejewski, J; Barbagallo, M; Bécares, V; Bečvář, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Bosnar, D; Brugger, M; Calviani, M; Calviño, F; Cano-Ott, D; Carrapiço, C; Cerutti, F; Chiaveri, E; Chin, M; Colonna, N; Cortés, G; Cortés-Giraldo, M A; Diakaki, M; Domingo-Pardo, C; Dzysiuk, N; Eleftheriadis, C; Ferrari, A; Fraval, K; Ganesan, S; Garcìa, A R; Giubrone, G; Gómez-Hornillos, M B; Gonçalves, I F; González-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Gurusamy, P; Jenkins, D G; Jericha, E; Kadi, Y; Käppeler, F; Karadimos, D; Koehler, P; Kokkoris, M; Krtička, M; Kroll, J; Langer, C; Lederer, C; Leeb, H; Losito, R; Manousos, A; Marganiec, J; Martìnez, T; Massimi, C; Mastinu, P F; Mastromarco, M; Meaze, M; Mendoza, E; Mengoni, A; Milazzo, P M; Mingrone, F; Mirea, M; Mondalaers, W; Pavlik, A; Perkowski, J; Plompen, A; Praena, J; Quesada, J M; Rauscher, T; Reifarth, R; Riego, A; Roman, F; Rubbia, C; Sarmento, R; Schillebeeckx, P; Schmidt, S; Tagliente, G; Tain, J L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Ventura, A; Versaci, R; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiß, C; Wright, T J; Žugec, P

    2012-01-01

    A fission reaction chamber was designed to measure the angular distribution of the fragments emitted in neutron-induced fission reactions at n_TOF. Up to ten Parallel Plate Avalanche Counters can be included and kept at controlled low-pressure gas. Counters are tilted 45º with respect to the neutron beam direction and up to nine targets can be interleaved in between. A first measurement of the 232Th(n,f) was recently done and preliminary experimental results demonstrating the suitability of the setup are presented here.

  8. Determination of photofission fragment characteristics of {sup 234,238}U and {sup 232}Th in the barrier region

    Goeoek, Alf

    2012-11-05

    The photofission of {sup 232}Th, {sup 234}U and {sup 238}U at excitation energies in the barrier region has been studied. The goal has been to extract information on the mass, total kinetic energy (TKE) and angular distributions of the fission fragments. The experiments were performed using bremsstrahlung, produced by an electron beam in a copper radiator at the injector of the Superconducting Darmstadt linear accelerator (S-DALINAC). Mass and TKE distributions were determined by means of the double kinetic energy technique using a twin Frisch grid ionization chamber. The angular distributions were derived simultaneously by measuring the drift time of ionization electrons. Results show that this drift-time method is comparable in accuracy to other more commonly used methods, but with a simplified procedure for setting up the experiment. Mass, TKE and angular distributions have been obtained from bremsstrahlung-induced fission of {sup 232}Th at average excitation energies left angle E{sub x} right angle =6.68 MeV and 7.26 MeV, for {sup 234}U at left angle E{sub x} right angle =5.80 MeV, 6.49 MeV and 7.23 MeV, and for {sup 238}U at left angle E{sub x} right angle =5.90 MeV, 6.11 MeV and 6.93 MeV. Results on fission fragment characteristics from {sup 238}U({gamma},f) show good agreement with literature data, which verifies the experimental procedure. The correlated mass and TKE data have been analyzed in terms of fission modes within the multi-modal random-neck-rupture model. The result exhibits a dominant yield of the mass asymmetric standard-2 mode in all the investigated fissioning nuclei, with a relative yield of {proportional_to}77 % in {sup 232}Th, {proportional_to}75 % in {sup 234}U and {proportional_to}67 % in {sup 238}U. No strong fluctuation of the mode yields were found as a function of the excitation energy. Correlations between mass, TKE and angular distributions have been investigated in {sup 232}Th and {sup 234}U. The correlation takes the form of an

  9. 238U, 232TH, AND 222RN concentration measured in various traditional medicinal plant preparation using nuclear track detectors

    Full text: 238U, 232Th, 222Rn concentrations were measured inside traditional medicinal plants preparations widely used by patients in classic and modern phyto therapy by using a technique based on the use of solid state nuclear track detectors. The intakes of these radionuclides have been determined for adult patients from the ingestion of the studied medical preparations. The influence of mass intake as well as pollution on the contents of the considered radionuclides was investigated. The resulting radiation doses to adult patients from the ingestion of the traditional medical preparations were evaluated.

  10. An integral experiment on thorium oxide/depleted uranium cylinders with D-T neutrons for 232Th(n, 2n) reaction

    Highlights: • An integral experiment for 232Th(n, 2n) reaction was carried out on the newly-established ThO2/depleted uranium cylinders. • 232Th(n, 2n) reaction rate distribution was obtained in the assemblies with an uncertainty of about 7%. • Experiments were analyzed by MCNP code with ENDF/B-VI.8, ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries. • Experimental results could be used to re-evaluate the cross sections of 232Th(n, 2n) reaction. - Abstract: In order to verify the evaluated cross sections of 232Th(n, 2n) reaction for the conceptual design of the thorium based subcritical blanket in the fusion–fission hybrid reactor, an integral experiment on thorium oxide/depleted uranium cylinders was carried out with D-T neutrons using the activation technique. 232Th(n, 2n) reaction rate distribution was obtained at the central axis direction in the assemblies with an uncertainty of about 7%. Experiments were analyzed by using MCNP code with ENDF/B-VI.8, ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries to validate the nuclear data libraries of 232Th(n, 2n) reaction, the calculated results with JENDL-4.0 agree with the measurements the best with discrepancies within the experimental uncertainty. The average values of C/E for the three benchmark assemblies are 1.058, 1.044 and 0.980. Calculations with different evaluated libraries in the benchmark assemblies show a large discrepancy. The experimental results can be used to re-evaluate the cross sections of the 232Th(n, 2n) reaction

  11. 238U, 232Th and 40K radioactivity level of soil and concrete floor in Zhuhai, Guangdong province, China

    In-situ gamma-ray spectrometer survey is carried out in Zhuhai, Guangdong province from 2002 to 2003 in order to estimate the radiation level of natural radionuclides. Measured area is more than 100 km2 and 970 sites with NaI(Tl) (φ75 mm x 75 mm) gamma-ray spectrometer. The specific activity of 40K, 238U and 232Th are 654.2 ± 338.0, 85.7 ± 31.6, and 159.9 ± 49.0 Bq·kg-1 in weathered granite, and 632.3 ± 75.1, 35.2 ± 14.6 and 70.2 ± 18.6 Bq·kg-1 in the sediments, respectively. Biotite Granite is the source of 40K, 238U and 232Th in the medium on ground in Zhuhai. The specific activity of natural radionuclides have significant dependence relation with geological background, such as lithology. (authors)

  12. Investigation of resonance structure and Doppler-effect of cross sections for 232 Th, 235 U and 239 Pu

    The results of measuring the neutron transmissions for 232 Th, 235 U and 239 Pu metal samples carried out at the 60 m, 123 m and 1006 m flight paths of the Dubna IBR-30 booster in the neutron energy range of 2 eV - 200 keV are given and discussed. The measurements were made at the room and liquid nitrogen temperatures. The batteries of 3 boron and 26 helium counters were used as detectors. The results of the calculations of analogous transmissions realized on the base of the evaluated data libraries BROND-2, ENDF/B-6 and JENDL-3 by means of the GRUCON computer program package are also given. It is concluded that the 235 U Doppler coefficients and effective total cross sections taken from measured transmissions are in a good agreement with calculation results based on the ENDF/B-6 library at energies of 2.15 eV - 200 keV. The BROND-2 and JENDL-3 parameters give the Doppler coefficients and effective cross sections which are 10-30% higher than the experimental and ENDF/B-6 ones at the resonance energies of 46.5 - 465 eV. For 239 Pu there is agreement of the experimental and calculational results within the experimental error limits. For 232 Th experimental values for the Doppler coefficients and effective cross sections are 10-15% higher than the calculated ones with all libraries in resonance energy region. 9 refs., 2 tabs., 1 fig

  13. Distribution of 226Ra, 232Th, and 40K in soils of Rio Grande do Norte (Brazil)

    A survey programme aimed at studying the environmental radioactivity in the Brazilian state of Rio Grande do Norte was undertaken. Fifty-two soil samples, together with two rock and two uraniferrous ore samples were collected from the eastern and central regions of this state. Concentrations of radioelements in samples were determined by γ-ray spectrometry. The average concentrations of 226Ra, 232Th, and 40K in the surveyed soils were 29.2 ± 19.5 (SD), 47.8 ± 37.3, and 704 ± 437 Bq kg-1, respectively. Higher values were found in the rock samples. The distributions of 226Ra and 232Th were fitted by log-normal curves. Radiological measurements carried out with a portable scintillometer at the sampled sites revealed an average absorbed dose rate of 55 ± 27 (SD) nGy h-1. Computed dose rates obtained through the Beck formula ranged from 15-179 nGy h-1, with a mean value of 72.6 ± 38.7 (SD) nGy h-1, and their distribution fitted a log-normal curve. An annual average effective dose equivalent of 552 μSν (range: 117-1361 μSν) was estimated for 51 sites in Rio Grande do Norte. (author)

  14. Primordial radioactivity ((238)U, (232)Th and (40)K) measurements for soils of Ludhiana district of Punjab, India.

    Badhan, K; Mehra, R

    2012-11-01

    The aim of the present work was to study the activity concentration and absorbed gamma dose rates due to primordial radionuclides ((238)U, (232)Th and (40)K) for the soil of different villages of Ludhiana district of Punjab, India using a high-purity germanium detector based on high resolution gamma-ray spectrometry. The average activity concentrations of (238)U, (232)Th and (40)K in the soil samples have been found to be 28.58, 50.95 and 569.59 Bq kg(-1), respectively, which gives the total gamma dose rate contribution of 68.50 nGy h(-1). To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the external hazard index, the absorbed dose rate and the effective dose rate have been calculated. The calculated radium equivalent activity values are on the lower side of the recommended safe limit value of 370 Bq kg(-1) by Organization of Economic and Control Department. The calculated value of external health hazard index is lower than unity. PMID:22899219

  15. Soil-to-root vegetable transfer factors for (226)Ra, (232)Th, (40)K, and (88)Y in Malaysia.

    Asaduzzaman, Kh; Khandaker, Mayeen Uddin; Amin, Y M; Bradley, D A; Mahat, R H; Nor, R M

    2014-09-01

    Soil-to-plant transfer factors (TFs) are of fundamental importance in assessing the environmental impact due to the presence of radioactivity in soil and agricultural crops. Tapioca and sweet potato, both root crops, are popular foodstuffs for a significant fraction of the Malaysian population, and result in intake of radionuclides. For the natural field conditions experienced in production of these foodstuffs, TFs and the annual effective dose were evaluated for the natural radionuclides (226)Ra, (232)Th, (40)K, and for the anthropogenic radionuclide (88)Y, the latter being a component of fallout. An experimental tapioca field was developed for study of the time dependence of plant uptake. For soil samples from all study locations other than the experimental field, it has been shown that these contain the artificial radionuclide (88)Y, although the uptake of (88)Y has only been observed in the roots of the plant Manihot esculenta (from which tapioca is derived) grown in mining soil. The estimated TFs for (226)Ra and (232)Th for tapioca and sweet potato are very much higher than that reported by the IAEA. For all study areas, the annual effective dose from ingestion of tapioca and sweet potato are estimated to be lower than the world average (290 μSv y(-1)). PMID:24814722

  16. Primordial radioactivity (238U, 232Th and 40K) measurements for soils of Ludhiana district of Punjab, India

    The aim of the present work was to study the activity concentration and absorbed gamma dose rates due to primordial radionuclides (238U, 232Th and 40K) for the soil of different villages of Ludhiana district of Punjab (India)) using a high-purity germanium detector based on high resolution gamma-ray spectrometry. The average activity concentrations of 238U, 232Th and 40K in the soil samples have been found to be 28.58, 50.95 and 569.59 Bq kg-1, respectively, which gives the total gamma dose rate contribution of 68.50 nGy h-1. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the external hazard index, the absorbed dose rate and the effective dose rate have been calculated. The calculated radium equivalent activity values are on the lower side of the recommended safe limit value of 370 Bq kg-1 by Organization of Economic and Control Dept.. The calculated value of external health hazard index is lower than unity. (authors)

  17. Natural radioactivity (226Ra, 232Th and 40K) and assessment of radiological hazards in the Kestanbol granitoid, Turkey.

    Canbaz, Buket; Cam, N Füsun; Yaprak, Günseli; Candan, Osman

    2010-09-01

    The surveys of natural gamma-emitting radionuclides in rocks and soils from the Ezine plutonic area were conducted during 2007. Direct dose measurement using a survey meter was carried out simultaneously. The present study, which is part of the survey, analysed the activity concentrations of (238)U, (232)Th and (40)K in granitoid samples from all over the region by HPGe gamma spectrometry. The activity concentrations of (226)Ra ranged from 94 to 637 Bq kg(-1), those of (232)Th ranged from 120 to 601 Bq kg(-1)and those of (40)K ranged from 1074 to 1527 Bq kg(-1) in the analysed rock samples from different parts of the pluton. To evaluate the radiological hazard of the natural radioactivity in the samples, the absorbed dose rate (D), the annual effective dose rate, the radium equivalent activity (Ra(eq)) and the external (H(ex)) hazard index were calculated according to the UNSCEAR 2000 report. The thorium-to-uranium concentration ratios were also estimated. PMID:20529959

  18. A dispersive optical model potential for nucleon induced reactions on 238U and 232Th nuclei with full coupling

    Chiba Satoshi

    2013-03-01

    Full Text Available A dispersive coupled-channel optical model potential (DCCOMP that couples the ground-state rotational and low-lying vibrational bands of 238U and 232Th nuclei is studied. The derived DCCOMP couples almost all excited levels below 1 MeV of excitation energy of the corresponding even-even actinides. The ground state, octupole, beta, gamma, and non-axial bands are coupled. The first two isobar analogue states (IAS populated in the quasi-elastic (p,n reaction are also coupled in the proton induced calculation, making the potential approximately Lane consistent. The coupled-channel potential is based on a soft-rotor description of the target nucleus structure, where dynamic vibrations are considered as perturbations of the rigid rotor underlying structure. Matrix elements required to use the proposed structure model in Tamura coupled-channel scheme are derived. Calculated ratio R(U238/Th232 of the total cross-section difference to the averaged σT for 238U and 232Th nuclei is shown to be in excellent agreement with measured data.

  19. Determination of specific concentrations of {sup 40}K, {sup 238}U and {sup 232}Th in mineral fertilizer samples

    Garcez, Ricardo W.D.; Lopes, Jose M.; Silva, Ademir X., E-mail: r.w.o.g@fisica.if.uff.br, E-mail: ademir@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Domingues, Alessandro M.; Lima, Marco F. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

    2015-07-01

    The use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as {sup 238}U, the {sup 232}Th, and their descendants, beyond {sup 40}K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of {sup 232}Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg{sup -1}, the values of {sup 238}U specific concentrations ranged from 16.0 to 647.7 Bq.Kg{sup -1} and {sup 40}K specific concentrations ranged from 19.1 to 12713 Bq.Kg{sup -1}. Concentrations of values are consistent with those found in literature. (author)

  20. Determination of specific activity of 226Ra, 232Th and 40K for assessment of environmental hazards

    Studies have been carried out using gamma-spectrometric techniques to determine the natural radioactivity in some rocks that are used as building materials in Yemen. The concentrations of the natural radionuclides namely 226Ra, 232Th and 40K in the rock samples collected from different rock markets in Yemen have been determined using an NaI(Tl) detector. The concentrations of 226Ra, 232Th and 40K in the studied rock samples range from 22.2 to 88.8 Bq kg-1, 8.12 to 113.68 Bq kg-1 and 31.3 to 2222.3 Bq kg-1, respectively. The concentrations of these radionuclides are compared with the typical world values. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, the representative level index and the values of both external and internal hazard indices were evaluated and compared with the internationally approved values. The radium equivalent activity values of all rock samples are lower than the limit of 370 Bq kg-1 except for one sample which is about 413.386. The values of external hazard index (Hex) and internal hazard index (Hin), absorbed doses in indoor air and the corresponding effective dose equivalents in a typical dwelling are presented. The need for further studies is also discussed. (authors)

  1. 8Dim calculations of the third barrier in $^{232}$Th and a conflict between theory and experiment on uranium nuclei

    Jachimowicz, P; Skalski, J

    2013-01-01

    We find the height of the third fission barrier $B_{III}$ and energy of the third minimum $E_{III}$ in $^{232}$Th using the macroscopic - microscopic model, very well tested in this region of nuclei. For the first time it is done on an 8-dimensional deformation hypercube. The dipole distortion is included among the shape variables to assure that no important shapes are missed. The saddle point is found on a lattice containing more than 50 million points by the immersion water flow (IWF) method. The shallow third minimum, $B_{III}-E_{III}\\approx 0.36$ MeV, agrees with experimetal data of Blons et al. This is in a sharp contrast with the status of the IIIrd minima in $^{232-236}$U: their experimental depth of $\\geq3$ MeV contradicts all realistic theoretical predictions. We emphasize the importance of repeating the experiment on $^{232}$Th, by a technique similar to that used in the uranium nuclei, for settling the puzzle of the third minima in actinides.

  2. 230Th/ 234U/ 238U and 231Pa/ 235U ages from a single fossil coral fragment by multi-collector magnetic-sector inductively coupled plasma mass spectrometry

    Mortlock, Richard A.; Fairbanks, Richard G.; Chiu, Tzu-chien; Rubenstone, James

    2005-02-01

    The 230Th/ 234U/ 238U age dating of corals via alpha counting or mass spectrometry has significantly contributed to our understanding of sea level, radiocarbon calibration, rates of ocean and climate change, and timing of El Nino, among many applications. Age dating of corals by mass spectrometry is remarkably precise, but many samples exposed to freshwater yield inaccurate ages. The first indication of open-system 230Th/ 234U/ 238U ages is elevated 234U/ 238U initial values, very common in samples older than 100,000 yr. For samples younger than 100,000 yr that have 234U/ 238U initial values close to seawater, there is a need for age validation. Redundant 230Th/ 234U/ 238U and 231Pa/ 235U ages in a single fossil coral fragment are possible by Multi-Collector Magnetic Sector Inductively Coupled Plasma Mass Spectrometry (MC-MS-ICPMS) and standard anion exchange column chemistry, modified to permit the separation of uranium, thorium, and protactinium isotopes from a single solution. A high-efficiency nebulizer employed for sample introduction permits the determination of both 230Th/ 234U/ 238U and 231Pa/ 235U ages in fragments as small as 500 mg. We have obtained excellent agreement between 230Th/ 234U/ 238U and 231Pa/ 235U ages in Barbados corals (30 ka) and suggest that the methods described in this paper can be used to test the 230Th/ 234U/ 238U age accuracy. Separate fractions of U, Th, and Pa are measured by employing a multi-dynamic procedure, whereby 238U is measured on a Faraday cup simultaneously with all minor isotopes measured with a Daly ion counting detector. The multi-dynamic procedure also permits correcting for both the Daly to Faraday gain and for mass discrimination during sample analyses. The analytical precision of 230Th/ 234U/ 238U and 231Pa/ 235U dates is generally better than ±0.3% and ±1.5%, respectively (2 Relative Standard deviation [RSD]). Additional errors resulting from uncertainties in the decay constant for 231Pa and from undetermined

  3. Measurement of fission cross sections and fragment angular distributions using solid state track detectors

    Fission cross sections and angular distributions of fission fragments from fissions induced by 14.1 and 15.8 MeV neutrons, respectively, in 232Th, 231Pa, 233U, 235U, 238U, 237Np, 239Pu and 241Am have been studied using Lexan plastic track detectors. A novel experimental set-up evolved from considerations of neutron economy allows simultaneous measurement of angular distribution of fission fragments from five independently fissioning nuclides at a time. The data on angular anistropy were analysed in the perspective of different chances of fissions taking place simultaneously in this energy region. Third-chance fission thresholds for 231Pa and 241Am were estimated from the measured anisotropy values to be 13.2 and 11.1 MeV, respectively. (author)

  4. 226Ra, 232Th and 40K analysis in sand samples from some beaches of Great Vitoria, Espirito Santo, Brazil: preliminary results

    The natural radioactivity in superficial beach sand samples of 7 beaches of Great Vitoria, metropolitan region of the State of Espirito Santo, southeast Brazil, was determined from the 226Ra, 232Th and 40K contents. The assessed beaches were Manguinhos, Camburi, Praia do Canto, Curva da Jurema, Itapua, Setibao and Areia Preta. Three samples of each beach were sealed in standard 100 mL polyethylene flasks and stored in order to obtain secular equilibrium in the 238U and 232Th series. All samples were measured by high resolution gamma spectrometry and the spectra were analyzed with the WinnerGamma software. The 232Th concentration was determined from the average concentrations of 228Ac, 212Pb and 212Bi and the 226Ra concentration was determined from the average concentrations of 214Pb and 214Bi. Preliminary results show concentrations varying from 9 Bq.kg-1 to 6035 Bq.kg-1 for 232Th, from 4 Bq.kg-1 to 575 Bq.kg-1 for 226Ra and from 13 Bq.kg-1 to 142 Bq.kg-1 for 40K. Areia Preta beach shows the highest values for 232Th, while the highest value for 226Ra was observed for Camburi beach. High values of 40K were observed for Curva da Jurema beach. (author)

  5. 237Np在破碎凝灰岩和凝灰质砂上的吸附研究%STUDY OF 237Np ADSORPTION ON CRUSHED TUFF AND TUFFACEOUS SAND

    王旭东; 田中忠夫; 武部慎一

    2001-01-01

    The adsorption characteristics of 237Np on crushed tuff andtuffaceous sand from northeast Japan have been studied using sequential extraction analysis technique. With a large difference in cation exchange capacity (CEC), both materials show nearly same sorptivity for 237Np. Together with dominance of ion exchange processes in sorption indicated by sequential extraction analysis, it suggests an absence of specific sorption at sites of this kind. It's interesting to find that sorption on Fe-Mn oxyhydroxide-oxides, defined by our sequential extraction procedure, almost keep constant for both cases, without time dependency. A potential mechanism of surface chemical reaction is deduced. Kinetics with respect to exchangeable and residual portions in tuff and fuffaceous sand confirms that some slow processes are controlling radionuclide sorption.%用连续提取法研究了237Np在破碎凝灰岩和凝灰质砂上的吸附。研究结果表明,48h以后,2种介质对237Np的吸附百分数相近,而且吸附的237Np在各相间的分布均以离子交换态为主。凝灰岩和凝灰质砂的阳离子交换容量差异显著,说明离子交换作用仅发生在粘土矿物的表面,凝灰岩中蒙脱石的层间没有发生阳离子交换。在28d的实验时间内,237Np在介质中的Fe-Mn氧化物-氢氧化物上的吸附百分数几乎不随时间变化。这可能是因为该吸附过程为瞬时即可完成的表面化学反应。介质内离子交换相和残余相上的吸附则显示为缓慢的吸附过程。

  6. About the first experiment on investigation of 129I, 237Np, 238Pu and 239Pu transmutation at the nuclotron 2.52 GeV deuteron beam in neutron field generated in U/Pb-assembly 'Energy plus transmutation'

    Preliminary results of the first experiment with energy 2.52 GeV at the electronuclear setup which consists of Pb-target (diameter 8.4 cm, length 45.6 cm) and natU-blanket (206.4 kg), transmutation samples of 129I, 237Np, 238Pu and 239Pu (radioecological aspect) are described. Hermetically sealed samples in notable amounts are gathered in atomic reactors and setups of industries which use nuclear materials and nuclear technologies were irradiated in the field of neutrons produced in the Pb-target and propagated in the natU-blanket. Estimates of transmutations were obtained as a result of measurements of gamma activities of the samples. The information about the space and energy distribution of neutrons in the volume of the lead target and the uranium blanket was obtained with the help of sets of activation threshold detectors (Al, Co, Y, I, Au, Bi and others), solid-state nuclear track detectors, 3He neutron detectors and nuclear emulsion. Comparison of the experimental data with the results of simulation with the MCNPX program was performed

  7. Challenges and solutions for random sampling of parameters with extremely large uncertainties and analysis of the 232Th resonance covariances

    Covariance data in the existing evaluated nuclear data libraries often include large relative uncertainties and mathematical inconsistencies, which arise especially in combination with random sampling. The 232Th evaluation from the ENDF/B-VII.1 library has been taken as an example. Possible solutions for mathematically impossible correlation matrices with negative eigenvalues and too low correlation coefficients between inherently positive parameters with large relative uncertainties are proposed. Convergence of the random sampling for lognormal distribution with extremely high relative standard deviations is slow by nature. Using weighted sampling, single parameters or a limited number of correlated parameters with large uncertainties can be sampled. Efficient sampling of a large number of correlated parameters with extremely large relative uncertainties remains unsolved

  8. Most probable charge of fission products in proton-induced fission of 238U and 232Th

    The charge distributions of fission products in proton-induced fission of 238U and 232Th were measured in a wide mass range. The most probable charges lay on the proton-rich side in the light fragment region and on the proton-deficient side in the heavy one compared with the unchanged charge distribution hypothesis. This result implies that the charge polarization occurs in the fission process. The charge polarization was examined with respect to the ground-state Q values. The estimations by the Q values fairly well reproduced the experimental most probable charges. These results suggest that the fission path to the most favorable charge division may go through the most energetically favorable path at scission point. (author)

  9. Measurement of neutron-transmission spectra through 232Th from 8 MeV to 4 keV

    Neutron transmission spectra through room-temperature 232Th samples have been measured by use of the time-of-flight technique, the ORELA pulsed neutron source, and a 1-mm-thick Li-glass detector. The measurement and data reduction are described in detail. The 40-m transmission spectra through eight samples are directly compared from 15 to 4000 eV with resolution-broadened transmission spectra calculated from the ENDF/B-V total cross section. Two sets of 22-m transmission spectra through five samples are combined into one total cross section from 0.008 to 15.0 eV and compared with the ENDF/B-V evaluation. 13 figures, 12 tables

  10. Measurement of the 232Th capture cross section in the energy region 5 keV-150 keV

    The 232Th(n,γ) neutron capture cross-section is of great importance for accelerator driven reactor (ADS) systems based on the Thorium-Uranium fuel cycle. An analysis of the required nuclear data, reveals that the status of the 232Th capture data is far from the requested 2 % uncertainty level. Recently 232Th average capture measurements, between 5-200 keV neutron energy, were performed at the FzK Karlsruhe (DE). A comparison of the measured averaged capture cross section with the evaluated data files shows a reasonable agreement in the neutron energy range above 15 keV. However, discrepancies of up to 40 % at lower neutron energies are observed. The same order of discrepancies is observed when comparing their results with the results obtained by Macklin et al. at ORELA. To clarify these discrepancies we measured at IRMM the average capture cross-section at the GEel LINear Accelerator (GELINA). The measurements were performed at a 14.37 m flight-path using the Time-Of-Flight (TOF) method. The gamma rays, originating from the 232Th(n,γ) reaction, were detected by a pair of C6D6-based liquid scintillators applying a pulse-height weighting method. The neutron flux was measured with an ionisation chamber placed at 80 cm before the Thorium sample. This chamber has a cathode loaded with two back-to-back layers of about 40 μg/cm210B. The sample consisted of a metallic natural thorium disc of 8 cm diameter and 0.5 mm thick, corresponding to a thickness of 1.588 10-3 at/b. The background for the capture measurements consists of a time independent and time dependent component. The former, mainly produced by the radioactive decay of the sample, was deduced from measurements with a closed beam. The latter was measured by replacing the thorium sample with a 0.5 mm thick 208Pb sample of the same size. Such a Pb sample has practically the same scattering probability as the thorium sample and has a negligible capture yield. Therefore, the 208Pb run provides a good estimate of

  11. Environmental geochemistry of 238U, 232Th, 40K and some heavy metals in River Nile sediments

    Environmental geochemistry is concerned with the abundance, distribution, and mobility of chemical elements in surface materials at the surface of earth crust. This study aimed at better understanding of geochemical behavior of 238U,23'2Th and 40K in river sediments and some heavy elements with emphasis on Mg, Ca, Mn, Fe, Ni, Cu, Zn and Pb. The analysis was conducted for a total of 33 bulk sediment samples from White Nile, Blue Nile and River Nile within Khartoum, the samples were fractionated into seven grain sizes each (2000-1000, 1000-500, 500-250, 250-200, 200-125, 125-100 and > 100 μm), using high resolution gamma spectrometer for radionuclides measurements, whereas Particle Induced X-ray Emission (PIXE) was used for heavy metals analysis. On the average, the activity concentration of 238U, 232Th and 40K were 17.90±5.23, 16.38±5.34 and 379.82±107.76 Bq -1Kg in White Nile, 19.56±5.04, 17.72±4.69, and 494.36±105.79 Bq -1Kg in Blue Nile and 19.27±2.88, 17.48±2.78, 359.50±83.15 Bq -1Kg in the River Nile sediments. Results revealed inverse relationship between activity concentration and grain size in White and Blue Nile, while the trend is not clear in the River Nile. In general, the variation of the measured values within single grain size was smaller in White Nile compare to Blue and River Nile sediments, and it was observed that the data are highly scattered in grain size (200-125μm). The ratio between 238U/232Th is grater than unity in the three rivers indicating that there is relative enrichment of 238U in the surface sediments. The activity concentration of the fallout radionuclide 137Cs is one order of magnitude lower in the White Nile sediments (0.89±0.96) Bq -1Kg compared to values in the Blue Nile sediments (3.60±1.55) Bq -1Kg. Comparison of the values obtained for natural radionuclides and the fallout radionuclide (137Cs in the three sites with the global data reflect low and /or insignificant difference. For heavy metal concentrations

  12. Radioactivity of 238U, 232Th, 40K, and 137Cs and assessment of depleted uranium in soil of the Musandam Peninsula, Sultanate of Oman

    SALEH, Ibrahim Hindawy

    2012-01-01

    238U, 232Th, 40K, and 137Cs radioactivities were determined in soil samples collected from the Musandam Peninsula, Sultanate of Oman, using a high resolution gamma-ray spectroscopy system. In addition, total uranium was measured in selected soil samples by inductively coupled plasma optical emission spectroscopy (ICP-OES). The averages of radioactivity levels in the soil for 238U, 232Th, and 40K were 14.42 Bq kg-1, 9.95 Bq kg-1, 158.21 Bq kg-1, and 2770 Bq m-2 for 137Cs, respectively...

  13. Dose rate due to 226Ra, 232Th and indoor 222Rn/220Rn in Bangalore city

    Human beings have always been exposed to ionizing radiation from various natural sources of radiation and one of the major routes of internal exposures is through inhalation of radioactivity present in the atmosphere. External exposure is caused by the gamma radiation from 40K and the daughter products of 238U and 232Th. It is known that as a result of inhalation of 222Rn a daughter product of decay chain of 238U and its daughter products, the equivalent dose to the entire lung is 20% and 45% higher than the equivalent dose in other tissues. The present study is carried out in Bangalore Metropolitan, India during 2007 to till date. Activity concentrations were measured by hyper pure germanium detectors and 222Rn, 220Rn concentrations were measured by solid state nuclear track detectors. The dose conversion factors reported by UNSCEAR have been used to estimate the indoor inhalation dose rates. The absorbed dose rates due to 226Ra and 232Th ranged between 0.59 and 1.44 mSvy-1 with an AM as 0.93 mSvy-1. Whereas the dose rates during winter and summer ranged between 0.20 and 4.14 mSvy-1 with an arithmetic value 1.8 and 0.7 mSvy-1 respectively. The dose rates in lower volume rooms were ranged from 2.38 to 3.47 mSvy-1 and from 0.75 and 3.28 mSvy-1 for the rooms of higher volume. The arithmetic mean values of dose rates in lower and higher volume rooms were 2.94 ± 0.14 mSvy-1 and 1.35 ± 0.03 mSvy-1 respectively. Higher concentrations were observed in lower volume rooms than higher volume room of all the monitored locations. The detailed experimental methodology and results are discussed. (author)

  14. Measurement of Fragment Mass Distributions in Neutron-induced Fission of {sup 238}U and {sup 232}Th at Intermediate Energies

    Simutkin, V.D. [Uppsala University, P.O Box 525, SE-751 20 Uppsala (Sweden)

    2008-07-01

    Conceptual analysis of accelerator-driven systems assumes extensive use of nuclear data on neutron-induced reactions at intermediate energies. In particular, information about the fission fragment yields from the {sup 238}U(n,f) and {sup 232}Th(n,f) reactions is of particular interest at neutron energies from 10 to 200 MeV. However, there is a lack of such data for both {sup 238}U and {sup 232}Th. Up to now, the intermediate energy measurements have been performed for {sup 238}U only, and there are no data for the {sup 232}Th(n,f) reaction. The aim of the work is to provide such data. Fission fragment mass distributions for the {sup 232}Th(n,f) and {sup 238}U(n,f) reactions have been measured for the incident neutron energies 32.8 MeV, 45.3 MeV and 59.9 MeV. The experiments have been performed at the neutron beam facility of the Universite Catholique de Louvain, Belgium. A multi-section Frisch-gridded ionization chamber has been used as a fission fragment detector. The data obtained have been interpreted in terms of the multimodal random neck-rupture model (MMRNRM). (authors)

  15. Target residues from the reaction of 3.65A GeV 12C with 232Th and 238U

    The cross sections for the production of about a hundred different radionuclides of 24Na - 237U range from the reaction of 3.65A GeV 12C with 232Th and 238U were measured by off-line gamma-ray spectroscopy. 5 refs.; 1 tab

  16. The activity concentrations of 40K, 226Ra, 232Th, 238U and 7Be in moss from spas in eastern Serbia in the period 2000-2012

    Čučulović Ana

    2014-01-01

    Full Text Available In this work we present the activity concentrations of natural radionuclides 40K, 226Ra, 232Th, 238U and 7Be in mosses. One hundred and sixty-seven moss samples were collected between 2001 and 2012 from the territory of the Sokobanja, Banja Jošanica and Gamzigradska Banja spas. They were classified into 23 species. The activity concentrations (Bq/kg in moss from Sokobanja spa were: 40K 25-427; 226Ra 0.3-36; 232Th 1.0-37; 238U 0.4-28 and 7Be 29-210; from Banja Jošanica spa they were: 40K 90-242; 226Ra 2.4-11.7; 232Th 2.0-12.7; 238U 1.6-11.3 and 7Be 142-212; Gamzigradska Banja spa: 40K 95-351; 226Ra 8.0-21; 232Th 5.1-19; 238U 6.7-18 and 7Be 20-144. The activity concentrations of dominant natural radionuclides (potassium, radium, thorium and uranium in the moss samples were within the usual ranges for the territory of Serbia. [Projekat Ministarstva nauke Republike Srbije, br. III 43009

  17. Comment on `Update of 40K and 226Ra and 232Th series $\\gamma$-to-dose conversion factors for soil'

    Malins, Alex; Saito, Kimiaki

    2015-01-01

    A letter to the editor of the Journal of Environmental Radioactivity on the article: E. Gasser, A. Nachab, A. Nourreddine, Ch. Roy, and A. Sellam, `Update of 40K and 226Ra and 232Th series $\\gamma$-to-dose conversion factors for soil', J. Environ. Radioactiv. 138, 68-71 (2014), DOI: 10.1016/j.jenvrad.2014.08.002.

  18. Distribution of 226Ra, 232Th and 40K in soils and sugar cane crops at Corumbatai river basin, Sao Paulo State, Brazil

    The common use of phosphate fertilizers NPK and amendments in sugar cane crops in Brazilian agriculture may increase the 226Ra, 232Th and 40K activity concentrations in soils and their availability for plants and human food chain. Thus, the main aim of this study was to evaluate the distribution of 226Ra, 232Th and 40K in soils and sugar cane crops in the Corumbatai river basin, Sao Paulo State, Brazil. The gamma spectrometry was utilized to measure the 226Ra, 232Th and 40K activity concentration in all samples. The soil-to-sugar cane transfer factors (TF) were quantified using the ratio between the radionuclide activity concentration in sugar cane and its activity concentration in soil. The results show that, although radionuclides incorporated in phosphate fertilizers and amendments are annually added in the sugar cane crops, if utilized in accordance with the recommended rates, their use does not lead to hazards levels in soils. The soil-to-sugar cane transfer of radionuclides occurred in the following order 40K>226Ra>232Th. Therefore, under these conditions, radionuclides intake through consumption of sugar is not hazardous to human health.

  19. Comparative study of fusion barrier distribution in 16O and 18O induced reactions on 232Th and 209Bi targets

    In order to investigate the influence of projectile excitations and transfer channels, quasi-elastic excitation function measurements with 16,18O projectile on two targets, one heavy (232Th) and the other a lighter target (209Bi) at energies around their Coulomb barrier are investigated. The results are compared with a new CC code CCFULL

  20. Intake of 238U and 232Th through the consumption of foodstuffs by tribal populations practicing slash and burn agriculture in an extremely high rainfall area

    The concentration of naturally occurring radionuclides 232Th, 238U was determined using Instrumental Neutron Activation Analysis (INAA) in different food groups namely cereals, vegetables, leafy vegetables, roots and tubers cultivated and consumed by tribal population residing around the proposed uranium mine. The study area is a part of rural area K. P. Mawthabah (Domiasiat) in the west Khasi Hills District of Meghalaya, India located in the tropical region of high rainfall that remains steeped in tribal tradition without much outside influence. Agriculture by Jhum (slash and burn) cultivation and animal husbandry are the main occupation of the tribal populations. A total of 89 samples from locally grown food products were analyzed. The concentration of 238U and 232Th in the soil of the study area was found to vary 1.6–15.5 and 2.0–5.0 times respectively to the average mean value observed in India. The estimated daily dietary intake of 238U and 232Th were 2.0 μg d−1 (25 mBq d−1) and 3.4 μg d−1 (14 mBq d−1) is comparable with reported range 0.5–5.0 μg d−1 and 0.15–3.5 μg d−1 respectively for the Asian population. - Highlights: ► 232Th, 238U were determined using Instrumental Neutron Activation Analysis (INAA). ► Study area located in the tropical region of high rainfall that remains steeped in tribal tradition. ► Agriculture by Jhum (slash and burn) cultivation and animal husbandry are the main occupation of the tribal populations. ► The estimated daily intake of 232Th and 238U in high rainfall area was found to be 3.4 and 2.0 μg respectively.

  1. Investigation of neutron spectra and transmutation of 129I, 237Np and other nuclides with 1.5 GeV protons from the Dubna Nuclotron using the electronuclear setup 'Energy plus Transmutation'

    Experiments which are part of the scientific program 'Investigations of physical aspects of electronuclear method of energy production and transmutation for radioactive waste of atomic energetics using relativistic beams from the JINR Synchrophasotron/Nuclotron' (project 'Energy plus Transmutation') are described. A large lead target surrounded by a four-section uranium blanket with a total weight of 206.4 kg natural uranium was irradiated with 1.5 GeV protons from the new cryogenic accelerator Nuclotron. Radiochemical sensors were exposed to the secondary particle fluences inside and on top of the target assembly. Two long-lived radioactive waste of atomic energetics sensors 129I and 237Np (approximately 1 g weight each) and stable nuclides 27Al, 59Co, 127I, 139La, 197Au and 209Bi as well as natural and enriched uranium were used. In addition, various solid state nuclear track detectors and nuclear emulsions were exposed simultaneously. The experimental results confirm the theoretical estimations that the neutron spectra around the U/Pb-assembly are dominated by medium- and high-energy neutrons as shown by the observation of (n, xn)-reaction products in Co, Au and Bi sensors. The yield of thermal neutrons on the surface of the U-blanket is strongly reduced as compared to the surface of a smaller Pb target surrounded with paraffin. The latter data were determined with (n, γ) reactions in stable La sensors. In this experiment the technique of nuclear emulsions has been applied for the first time to measurements of neutron spectra in an accelerator driven system

  2. 230Th, 232Th and 238U determinations in phosphoric acid fertilizer and process products by ICP-MS

    Through processing of Santa Quiteria-CE mine phosphate rock, Brazil has established a project for production of phosphoric acid fertilizer and uranium as a by-product. Under leaching conditions of phosphate rock with sulfuric acid, which is the common route for preparing phosphoric acid fertilizer, a large part of uranium, thorium and their decay products naturally present in the rock are solubilized. In order to assess the contamination potential in phosphoric acid and others process products, this paper describes a previous precipitation and direct methods for routine analysis of thorium and uranium isotopes by ICP-MS. In all samples, 230Th, 232Th and 238U were directly determined after dilution, except 230Th in phosphoric acid loaded with uranium sample, which to overcome equipment contamination effect, was determined after its separation by oxalate precipitation using lanthanum as a carrier. The results obtained by the proposed method by ICP-MS, were in good agreement when compared to alpha spectrometry for 230Th, and ICP-OES and spectrophotometry with arsenazo III for elementary uranium and thorium determinations. (author)

  3. Distribution of radioactive pollution of 238U, 232Th, 40K and 137Cs in northwestern coasts of Persian Gulf, Iran

    A reconnaissance study has been made of the distribution of 238U, 232Th, 40K and 137Cs and geochemical features in soils and sediments samples at various locations in the northwestern coast of Persian Gulf. Activity concentration levels due to radionuclides were measured in 30 soil and sediment samples collected from this region. From the measured spectra, activity concentrations were determined for 40K (range from 146 to 500 Bq kg-1), 137Cs (from 5 to 20 Bq kg-1), 238U (from 21 to 65 Bq kg-1) and 232Th (from 15 to 45 Bq kg-1) with lowest limit detection (LLD) of 68, 3.2, 4.3 and 4.3 Bq kg-1, respectively. The dose rate from ambient air at the soil ranges was between 19 and 58 nGy h-1 with an average of 37.41 ± 9.66 nGy h-1

  4. Assessment of 226Ra, 232Th and 40K activity in soil around the Uranium Mining and Processing Facility at Tummalapalle

    By using high purity germanium detector with high resolution gamma spectroscopy, various radionuclides were estimated quantitatively in different soil samples collected around Tummalapalle mining and milling facility. The activity concentration of 226Ra, 232Th and 40K as well as other radiological parameters were determined in the soil. The mean activity concentration of 226Ra, 232Th and 40K in soil were 53.22, 52.14 and 859.95 Bqkg-1, respectively, which are comparable with reported values elsewhere. The mean outdoor annual effective dose to the general public from the radionuclides present in the soil was estimated to be 0.11±0.02 mSvy-1, which is about 4.6 % of worldwide average annual exposure to natural radiation sources of 2.4 mSv as reported by UNSCEAR (2000). (author)

  5. Distribution of 226 Ra, 232 Th, 40 K and 137 Cs in soils of Province of Camaguey, Cuba

    A survey programme aimed at studying the environmental radioactivity in the Province of Camaguey in the eastern region of Cuba was undertaken. The average concentrations of 226 Ra, 232 Th, and 40 K in the surveyed soils were 26.4, 11.5 and 210 Bq.kg-1, respectively. The man-made radionuclide found was 137 Cs and its concentration was similar to those reported in regions affected only by global radioactive fallout, (7.9 Bq.kg-1). Radiological measurements carried out with a portable ionization chamber RSS-112 at the sampled sites revealed an average outdoor absorbed dose rate of 59.0 nGy.h-1 due to cosmic rays and terrestrial gamma radiation. Computed dose rates obtained through the UNSCEAR(1993) dose coefficients range from 4-182 nGy.h-1, with a mean value of 27.8 nGy.h-1, due to natural terrestrial gamma radiation. Ratio of Indoor to Outdoor absorbed dose rates in air was 1.75. The average value of absorbed dose rate in air for the ionizing component of cosmic rays was 31.8 nGy.h-1 at sea level. Because of the 95% of the Camaguey population lives at altitudes close to sea level (10-100 m), the absorbed dose rate in outdoor air from ionizing component of cosmic rays was estimated to be 32.3 nGy.h-1. An annual average effective dose equivalent of 510 μSv was estimated for Camaguey population due to the ionizing component of cosmic and gamma terrestrial radiation. This value is lower than the 760 μSv.year-1 estimated as a world average by UNSCEAR (1993). (author)

  6. Dietary 232Th and 238U intakes for Japanese as obtained in a market basket study and contributions of imported foods to internal doses

    Thorium-232 and 238U contents in four food groups were measured by inductively coupled plasma mass spectrometry (ICP-MS). Daily intakes of 232Th and 238U for Japanese were estimated to 2.22 mBq and 15.5 mBq per person, respectively. Furthermore, preliminary estimations were made for the effects of imported foods on internal exposures for Japanese. (author). 16 refs., 1 fig., 3 tabs

  7. 232Th(d,4n)230Pa cross-section measurements at ARRONAX facility for the production of 230U

    Introduction: 226Th (T1/2 = 31 min) is a promising therapeutic radionuclide since results, published in 2009, showed that it induces leukemia cells death and activates apoptosis pathways with higher efficiencies than 213Bi. 226Th can be obtained via the 230U α decay. This study focuses on the 230U production using the 232Th(d,4n)230Pa(β−)230U reaction. Methods: Experimental cross sections for deuteron-induced reactions on 232Th were measured from 30 down to 19 MeV using the stacked-foil technique with beams provided by the ARRONAX cyclotron. After irradiation, all foils (targets as well as monitors) were measured using a high-purity germanium detector. Results: Our new 230Pa cross-section values, as well as those of 232Pa and 233Pa contaminants created during the irradiation, were compared with previous measurements and with results given by the TALYS code. Experimentally, same trends were observed with slight differences in orders of magnitude mainly due to the nuclear data change. Improvements are ongoing about the TALYS code to better reproduce the data for deuteron-induced reactions on 232Th. Conclusions: Using our cross-section data points from the 232Th(d,4n)230Pa reaction, we have calculated the thick-target yield of 230U, in Bq/μA·h. This value allows now to a full comparison between the different production routes, showing that the proton routes must be preferred

  8. Distribution of 226Ra, 232Th, and 40K in rice plant components and physico-chemical effects of soil on their transportation to grains

    Mohammed Saad Alsaffar

    2015-07-01

    Full Text Available Radioactivity distribution and transfer factor (TF in plants are crucial parameters used to assess radioactive contamination in the environment and its risks to humans. In this study, the activities of 226Ra, 232Th, and 40K were successfully measured via gamma-ray spectrometry on rice plant components (root, straw, husk, and grain and on corresponding soil samples collected from paddy fields in Penang, Malaysia. Soil physico-chemical characteristics (pH, cation exchange capacity, electrical conductivity, organic matter, and soil texture were also analyzed for their estimated effects on soil–grain TF. A major fraction of the total 226Ra and 232Th activities measured as 47% and 57%, respectively, were concentrated in the roots, whereas only about 9% and 8% were distributed in the grains, correspondingly. 40K activity accumulation was about 59% in the straw and 7% in the grains. Rice soil–grain TFs were observed in the ranges of (0.06–0.36 × 10−1 for 226Ra, (0.04–0.14 × 10−1 for 232Th, and (0.74–4.72 × 10−1 for 40K. Results showed that the selected radionuclide distributions in rice are dependent on component type, and their grain concentrations are not linearly related to their soil concentrations. These findings indicated that uptake predominantly depends on soil physico-chemical characteristics.

  9. Determination of 238U, 232Th and 40K activity concentrations in riverbank soil along the Chao Phraya river basin in Thailand

    The activity concentrations of 238U, 232Th and 40K in riverbank soil along the Chao Phraya river basin was determined through gamma-ray spectrometry measurements made using a hyper-pure germanium detector in a low background configuration. The ranges of activity concentrations of 238U, 232Th and 40K were found to be 13.9 ↔ 76.8, 12.9 ↔ 142.9 and 178.4 ↔ 810.7 Bq kg−1, respectively. The anthropogenic radionuclide, 137Cs, was not observed in statistically significant amounts above the background level in the current study. The absorbed gamma dose rate in air at 1 m above the ground surface, the outdoor annual effective dose equivalent, the values of the radium equivalent activity and the external hazard index associated with all the soil samples in the present work were evaluated. The results indicate that the radiation hazard from primordial radionuclides in all soil samples from the area studied in this current work is not significant. - Highlights: • Radioactivity in surface soils from the Chao Phraya river basin in Thailand is evaluated. • Gamma-ray spectrometric analysis is to identify decays associated with 226Ra, 232Th and 40K. • The results provide baseline measurements for any changes in future radioactivity levels

  10. A preliminary study on 226Ra, 232Th, 40K and 137Cs activity concentrations in vegetables and fruits frequently consumed by inhabitants of Elazig Region, Turkey

    Determining radioactivity levels in foodstuffs is of great importance for the protection of human health. In addition, the literature includes few studies related to this subject in Turkey. In this study, gamma spectroscopic system was used in order to measure 226Ra, 232Th, 40K and 137Cs activity concentrations in vegetables and fruits produced in Elazig( Region. The average activity concentrations in vegetables was calculated as 0.64 ± 0.26 Bq kg-1 for 226Ra, 0.65 ± 0.14 Bq kg-1 for 232Th, 13.98 ± 1.22 Bq kg-1 for 40K, and 0.54 ± 0.04 Bq kg-1 for 137Cs. The average activity concentrations in fruits were 1.52 ± 0.34, 0.98 ± 0.23, 18.66 ± 1.13 and 0.59 ± 0.16 Bq kg-1, respectively for 226Ra, 232Th, 40K and 137Cs. Total committed effective dose value was determined as 20 and 30.55 μSv y-1, respectively for vegetables and fruits. The findings were compared with previous data reported for Turkey and other regions of the world. (author)

  11. Determination of {sup 228}Th, {sup 232}Th, and{sup 228}Ra in wild mushroom from a naturally high radioactive region in Brazil

    Rosa, Mychelle M.L.; Taddei, Maria Helena T.; Silva, Marco A.; Ferreira, Marcelo T., E-mail: mychelle@cnen.gov.b, E-mail: mhtaddei@cnen.gov.b, E-mail: masilva@cnen.gov.b, E-mail: ferreira@cnen.gov.b [Brazilian Nuclear Energy Commission (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Lab. of Pocos de Caldas; Maihara, Vera A., E-mail: vmaihara@ipen.gov.b [Nuclear and Energy Research Institute (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Mushrooms are fungi which efficiently accumulate radionuclides, as verified by radiochemistry analyses of specimens collected in contaminated areas, specifically after the Chernobyl nuclear accident. Many studies have demonstrated that mushrooms can be used in monitoring of ecosystem contamination and quality. The present paper is part of a broader study conducted in the Pocos de Caldas plateau region in Minas Gerais, Brazil, investigating assimilation of natural Uranium and Thorium radionuclide series by mushrooms. This region has elevated natural radioactivity due to the presence of radiological anomalies of volcanic origin. These anomalies are ore bodies containing Uranium and Thorium, the later being highly predominant. Many researchers have been conducted concerning radionuclide incorporation by agricultural products on the plateau. The present paper aims to determine {sup 232}Th, {sup 228}Th, and {sup 228}Ra radionuclides in wild mushrooms collected at different locations in the plateau region. {sup 228}Ra was determined by radiochemical separation using sulphate coprecipitation followed by beta radiometry. {sup 232}Th and {sup 228}Th were determined using anion exchange resin purification followed by alpha spectrometry. Higher values were obtained to {sup 228}Th than to {sup 232}Th. This is due to higher {sup 228}Ra mobility, which decays to {sup 228}Th. The accuracy of the analytical methods employed was evaluated using the reference sample IAEA Soil 327. These methods had high chemical recovery and high sensitivity. It was possible to confirm that mushrooms accumulate radionuclide and so can be used in environmental contamination and quality assessment. (author)

  12. {sup 238}U and {sup 232}Th concentrations in various foodstuffs in Morocco and resulting radiation doses to the members of the public; Concentrations en {sup 238}U et {sup 232}Th dans differents aliments au Maroc et doses de radiations en resultant pour les membres du public

    Misdaq, M.A.; Elamyn, H.; Erramli, H. [Cadi Ayyad Univ., Nuclear Physics and Techniques Lab., Faculty of Sciences Semlalia, Marrakech (Morocco)

    2008-04-15

    Uranium ({sup 238}U) and thorium ({sup 232}Th) concentrations were measured in different foods widely consumed in Morocco by using C.R.-39 and L.R.-115 type II solid state nuclear track detectors (S.S.N.T.D.). Data obtained were compared to those obtained by using isotope dilution mass spectrometry (I.D.M.S.). Total daily intakes of {sup 238}U and {sup 232}Th for a typical food basket were estimated to be 1.3 {+-} 0.1 mBq d{sup -1} and 0.98 {+-} 0.08 mBq d{sup -1}, 1.4 {+-} 0.1 mBq d{sup -1} and 1.06 {+-} 0.08 mBq d{sup -1}, 1.7 {+-} 0.1 mBq d{sup -1} and 1.26 {+-} 0.08 mBq d{sup -1} and 2.0 {+-} 0.1 mBq d{sup -1} and 1.5 {+-} 0.1 Bq d{sup -1} for the 2-7 years, 7-12 years, 12-17 years and adult's age groups, respectively. Alpha-activities due to annual {sup 238}U and {sup 232}Th intakes from the ingestion of the studied foodstuffs were determined in different organs and tissues of the human body of members of the public by using the ICRP gastrointestinal tract and systemic part models for these radionuclides. Committed equivalent doses due to annual intakes of {sup 238}U and {sup 232}Th were evaluated in the human body organs and tissues for different age groups of the Moroccan population by exploiting data obtained for alpha-doses deposited by 1 Bq of {sup 238}U and 1 Bq of {sup 232}Th in the considered human organs and tissues. The influence of the mass of the target tissue and activities due to {sup 238}U and {sup 232}Th on the committed equivalent doses due to annual intakes of these radionuclides in the organs and tissues of the human body was studied. (authors)

  13. Determination of radioactivity level of 238U, 232Th and 40K in surface medium in Zhuhai city by in-situ gamma-ray spectrometry

    A gamma-ray spectrometry survey with NaI(Tl) (φ75mm x 75mm) has been performed on a large scale to determine the distribution of 40K, 238U and 232Th in soil and rocks in Zhuhai, a southern Chinese city located in Guangdong Province. The survey sampled 970 sites which covered an area of more than 100 km2. The average activities of 40K. 238U and 222Th were found 655±338, 85.8±31.6, and 159.8±49.0 Bq·kg-1 in soil or cement of pavement in the urban area; 832±455, 87.3±41.6, and 179.3±40.7 Bq·kg-1 in weathered granite; 634±76.8, 35.2±14.6 and 70.2±18.6Bq·kg-1 in the Quaternary sediments in Doumen District. The average 232Th activity (159.8±49.0 Bq·kg-1) is above the average in both China (49 Bq·kg-1) and the world (30 Bq·kg-1). Terrestrial air-absorbed dose rates calculated from the above activities are 85.08±15.63, 183.33±40.80 nGy·h-1 respectively over the Quaternary sediments and weathered granite, and 163.49±30.15 nGy·h-1 in the urban area. The average calculated air-absorbed dose rate is about 12.63% larger than the value measured by a portable plastic scintillator dosemeter. The 40K, 238U and 232Th activities in surface medium are mainly originated from biotite granites, as indicated by a strong correlation between the radioactivity level and geological lithology in the surveyed area. (author)

  14. Assessment of environmental 226Ra, 232Th and 40K concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia

    Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h−1 and 1.169 mSv y−1, respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of 232Th, 226Ra and 40K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg−1 for 232Th, 12 ± 1 to 968 ± 27 Bq kg−1 for 226Ra, and 12 ± 2 to 2450 ± 86 Bq kg−1 for 40K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg−1 and 70 ± 20 to 4690 ± 90 Bq kg−1, respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000. -- Highlights: • Assessment of the activities in region of elevated radiation in Segamat District. • The average dose rate found to be six times higher than the world average. • The activity of 232Th is six times world average. • The activity of 226Ra is four times and 40K is lower than world average. • A digital map plotted for isodose

  15. Analysis of 226Ra, 232Th 40К and 137Cs in samples of soil from some areas of Republic of Macedonia by using gamma spectrometry

    Todorovik Aleksandra

    2012-01-01

    Full Text Available Taking into consideration the importance of the distribution and transfer of radio nuclides in soil, an attempt was made in this work to determine the concentration of 226Ra, 232Th 40К and 137Cs in the same. The concentrations of activity in the gamma-absorbed dose rates of the terrestrial naturally occurring radio nuclides, as follows, 226Ra, 232Th and 40K were determined in samples of soil collected from some parts of Republic of Macedonia, i.e. from three major cities in the Republic of Macedonia. The samples are taken by means of a special dosage dispenser which enables sampling of samples at a depth of 0-5 cm, 5-10cm and 10-15cm, thus disabling the sampling above these layers of soil. An identification of radio nuclides and assessment of their activity has been performed by applying gamma spectrometry. The time of counting for each sample was 65000 s. in order to obtain statistically small mistake. The spectrums were analyzed by a commercially available software GENIE-2000 received from Canberra, Austria. The activity of soil had wide range of values: 20.3 to 82.9 Bq kg-1for 226Ra, 16.1 to 82.5 Bq kg-1 for 232Th, 325 to 799.0 Bq kg-1for 40К and 9.1 to 24.3 Bq kg-1for 137Cs, respectively. The concentrations of these radio nuclides have been compared with the available data from the other countries. Natural environmental radioactivity and the associated external exposure due to gamma radiation depend primarily on the geological and geographical conditions. Namely, the specific levels of terrestrial environmental radiation are related to the type of rocks from which the soils originate. The obtained data indicate that the average value of activity of 232Th is about higher than the one of 226Ra The concentration of activity of 40К in the soil has greater value than 32Th and 226Ra in all soils. The causes for the existence of 137Cs in these soils are the nuclear explosions, waste radioactive materials and other incidents. It reaches the

  16. Cost-based optimizations of power density and target-blanket modularity for {sup 232}Th/{sup 233}U-based ADEP

    Krakowski, R.A.

    1995-07-01

    A cost-based parametric systems model is developed for an Accelerator-Driven Energy Production (ADEP) system based on a {sup 232}Th/{sup 233}U fuel cycle and a molten-salt (LiF/BeF{sub 2}/ThF{sub 3}) fluid-fuel primary system. Simplified neutron-balance, accelerator, reactor-core, chemical-processing, and balance-of-plant models are combined parametrically with a simplified costing model. The main focus of this model is to examine trade offs related to fission power density, reactor-core modularity, {sup 233}U breeding rate, and fission product transmutation capacity.

  17. Experimental Neutron-Induced Fission Fragment Mass Yields of 232Th and 238U at Energies from 10 to 33 MeV

    Simutkin, V. D.; Pomp, S.; Blomgren, J.; Österlund, M.; R. Bevilacqua; Ryzhov, I. V.; Tutin, G. A.; Yavshits, S. G.; Vaishnene, L. A.; Onegin, M S; Meulders, J.P.; Prieels, R.

    2013-01-01

    Development of nuclear energy applications requires data for neutron-induced reactions for actinides in a wide neutron energy range. Here we describe measurements of pre-neutron emission fission fragment mass yields of 232Th and 238U at incident neutron energies from 10 to 33 MeV. The measurements were done at the quasi-monoenergetic neutron beam of the Louvain-la-Neuve cyclotron facility CYCLONE; a multi-section twin Frisch-gridded ionization chamber was used to detect fission fragments. For...

  18. Daily intake of /sup 234,235,238/U, /sup 228,230,232/Th and /sup 226,228/Ra by New York City residents

    The daily intake of long-lived alpha-emitting members of the U, Th and Ac series by New York City residents has been estimated from measurements of diet, water and air samples. The total daily intakes from inhalation, food and water consumption in mBq are 18 (234U), 0.7 (235U), 16 (238U), 6 (230Th), 4 (232Th) and 52 (226Ra). From this, we infer that the total daily intakes of 228Th and 228Ra are 4 and 35 mBq, respectively

  19. Quantification of transfer of {sup 238}U, {sup 226}Ra, {sup 232}Th, {sup 40}K and {sup 137}Cs in mosses of a semi-natural ecosystem

    Dragovic, S., E-mail: sdragovic@inep.co.r [Institute for the Application of Nuclear Energy - INEP, University of Belgrade, Banatska 31b, 11080 Belgrade (Serbia); Mihailovic, N. [Institute for the Application of Nuclear Energy - INEP, University of Belgrade, Banatska 31b, 11080 Belgrade (Serbia); Gajic, B. [Faculty of Agriculture, Institute of Land Management, Laboratory of Soil Physics, University of Belgrade, Nemanjina 6, 11081 Belgrade (Serbia)

    2010-02-15

    There is a lack of appropriate data on transfer of some radionuclides on many terrestrial biota groups. To expand the available data concentration ratios of {sup 238}U, {sup 226}Ra, {sup 232}Th, {sup 40}K and {sup 137}Cs in mosses are presented in this paper. The relationship between concentration ratios of radionuclides and physicochemical characteristics of the underlying soil was also investigated. The data on concentration ratios obtained here will provide a useful addition to the currently used database of transfer parameters, particularly for natural radionuclides.

  20. Measurement of double-differential neutron emission cross sections of 238U, 232Th and 12C for 18 MeV neutrons

    Double-differential neutron emission cross sections of 238U, 232Th and 12C have been measured for 18-MeV incident neutrons using the neutron time-of-flight technique and Tohoku University 4.5MV Dynamitron accelerator as a pulsed neutron generator. In the experiment, energy resolution of the spectrometer was improved by employing a newly developed post-acceleration beam-chopper and by adjustment of timing property of the neutron detector. Measurements were made at laboratory angles between 30- and 145- deg., and data were obtained for secondary neutrons between 0.8 and 18 MeV. In the data processing, a care was taken for the data correction for the effects of parasitic neutrons associated with primary neutrons; the correction proved to be of special importance in the present measurement. We compared the data obtained in the present experiment with the evaluated data, JENDL-3 and ENDF/B-IV (B-V for 12C), and discussed the origin of the discrepancies. The anisotropy observed for secondary neutrons from 238U and 232Th was found to be reproduced by Kalbach-Mann systematics on the assumption of isotropy of fission neutrons. The experimental results for 12C showed marked discrepancies concerning the scattering cross sections and neutron spectrum in the continuum region. (author)

  1. Daily ingestion of 232Th, 238U, 226Ra, 228Ra and 210Pb in vegetables by inhabitants of Rio de Janeiro City

    The concentrations of the naturally occurring radionuclides 232Th, 238U, 210Pb, 226Ra and 228Ra were determined in the vegetables (leafy vegetables, fruit, root, bean and rice) and derived products (sugar, coffee, manioc flour, wheat flour, corn flour and pasta) consumed most by the adult inhabitants of Rio de Janeiro City. A total of 88 samples from 26 different vegetables and derived products were analyzed. The highest contribution to radionuclide intake arises from bean, wheat flour, manioc flour, carrot, rice, tomato and potato consumption. The estimated daily intakes due to the consumption of vegetables and derived products are 1.9 mBq of 232Th (0.47 μg), 2.0 mBq of 238U (0.17 μg), 19 mBq of 226Ra, 26 mBq of 210Pb and 47 mBq of 228Ra. The estimated annual effective dose due to the ingestion of vegetables and their derived products with the long-lived natural radionuclides is 14.5 μSv. Taking into account literature data for water and milk from Rio de Janeiro the dose value increases to 29 μSv, with vegetables and derived products responsible for 50% of the dose and water for 48%. 210Pb (62%) and 228Ra (24%) were found to be the main sources for internal irradiation

  2. Use of LabSOCS for determination of specific concentrations of 40K, 238U and 232Th in fertilizer samples

    Use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as 238U, the 232Th, and their descendants, beyond 40K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of 232Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg-1 , the values of 238U specific concentrations ranged from 16.0 to 647.7 Bq.Kg-1 and 40K specific concentrations ranged from 19.1 to 12713 Bq.Kg-1 . Concentrations of values are consistent with those found in literature. (author)

  3. Estimation of dose contribution from 226Ra, 232Th and 40K radon exhalation rates in soil samples from Shivalik foot hills in India.

    Chauhan, R P; Chauhan, Pooja; Pundir, Anil; Kamboj, Sunil; Bansal, Vakul; Saini, R S

    2014-01-01

    The concentration of radium, thorium and potassium and radon exhalation rates in soil samples collected from Shivalik foot hills in the states of Haryana and Himachal Pradesh (India) were experimentally measured. A high-resolution gamma-ray spectroscopic system was used for the measurement of natural radioactivity ((226)Ra, (232)Th and (40)K) at Inter-University Accelerator Center, New Delhi, using a coaxial n-type high-purity germanium detector (EG&G, ORTEC, Oak Ridge, USA). The mass exhalation rates (EM) of radon in soil samples from the study area measured by 'sealed canister technique' using LR-115 type II track detectors varied from 50±1 to 143±6 mBqkg(-1) h(-1). The activity concentrations of (226)Ra, (232)Th and (40)K in various soil samples of the study area varied from 31±1.3 to 63±4.6, 53±1.8 to 78±2.6 and 472±4.8 to 630±7.0 Bq kg(-1) respectively. The results indicated some higher levels of radioactivity in Lal Dhang peak area of the hills compared with other locations under study. PMID:23893776

  4. Distribution of 238U, 232Th, 40K, and 137Cs concentrations in soil samples nearby a nuclear laboratory, Capao Island, Brazil

    Oliveira Luciano S.R.

    2015-01-01

    Full Text Available Absolute soil concentrations of 238U, 232Th, 40K, and 137Cs samples were measured using high-resolution gamma spectrometry. The area of interest encompasses an embankment in a mangrove swamp in Guaratiba, Rio de Janeiro, called Capao Island, where nuclear, chemical and biological defense laboratories of the Brazilian Army Technology Center are in operation for more than 30 years. In order to ensure that no significant environmental impact has resulted from neutron physics experiments performed in a graphite exponential pile in addition to the operation of two cesium-driven irradiating facilities, radiation monitoring of the isotopes was carried out. A total of eight 250 ml soil samples were extracted within an area of 300 m x 300 m. No trace of 137Cs was detected and the measured levels of 238U were found to be close to the global mean. However, some data that slightly exceeded the expected normal range for 232Th (60 % of samples and 40K (20 % of samples should be attributed to the construction debris (cement, rocks, and sand used in the embankment at the site. Since there is no handling of those isotopes at that site or adjacent facilities that could affect their presence, it was concluded that no detectable contamination has occurred.

  5. Measurement of the intrinsic radiopurity of {sup 137}Cs/{sup 235}U/{sup 238}U/{sup 232}Th in CsI(Tl) crystal scintillators

    Zhu, Y.F. [Department of Engineering Physics, Tsing Hua University, Beijing (China); Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Lin, S.T. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Department of Physics, National Taiwan University, Taipei, Taiwan (China); Singh, V. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Department of Physics, Banaras Hindu University, Varanasi (India); Chang, W.C. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Deniz, M. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Department of Physics, Middle East Technical University, Ankara (Turkey); Lai, W.P. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Li, H.B. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Li, J. [Department of Engineering Physics, Tsing Hua University, Beijing (China); Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Institute of High Energy Physics, Chinese Academy of Science, Beijing (China); Li, Y.L. [Department of Engineering Physics, Tsing Hua University, Beijing (China); Liao, H.Y. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Department of Physics, National Taiwan University, Taipei, Taiwan (China); Lee, F.S. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Wong, H.T. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China)]. E-mail: htwong@phys.sinica.edu.tw; Wu, S.C. [Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Yue, Q. [Department of Engineering Physics, Tsing Hua University, Beijing (China); Zhou, Z.Y. [Department of Nuclear Physics, Institute of Atomic Energy, Beijing (China)

    2006-02-15

    The inorganic crystal scintillator CsI(Tl) has been used for low energy neutrino and Dark Matter experiments, where the intrinsic radiopurity is an issue of major importance. Low-background data were taken with a CsI(Tl) crystal array at the Kuo-Sheng Reactor Neutrino Laboratory. The pulse shape discrimination capabilities of the crystal, as well as the temporal and spatial correlations of the events, provide powerful means of measuring the intrinsic radiopurity of {sup 137}Cs as well as the {sup 235}U, {sup 238}U and {sup 232}Th series. The event selection algorithms are described, with which the decay half-lives of {sup 218}Po, {sup 214}Po, {sup 22}Rn, {sup 216}Po and {sup 212}Po were derived. The measurements of the contamination levels, their concentration gradients with the crystal growth axis, and the uniformity among different crystal samples, are reported. The radiopurity in the {sup 238}U and {sup 232}Th series are comparable to those of the best reported in other crystal scintillators. Significant improvements in measurement sensitivities were achieved, similar to those from dedicated massive liquid scintillator detector. This analysis also provides in situ measurements of the detector performance parameters, such as spatial resolution, quenching factors, and data acquisition dead time.

  6. High-temperature X-ray diffraction studies on La1-2xCaxThxPO4(s) (x = 0, 0.25, 0.5) solid-solution

    Advanced Heavy Water Reactor (AHWR), Compact High Temperature Reactor (CHTR) and Accelerator Driven System (ADS) are being developed in India to use 232Th-233U fuel cycle. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (231Th), which are insufficient to initiate a nuclear chain reaction. It can be used with 233U, 235U and 239Pu as fissile fuel. Because of it, the back end of thorium fuel cycle contains long-lived 231Pa, 229Th, 230Th and low level of minor actinides (237Np, 241Am, 243Am, 244Cm) for final disposal in geological repositories. From a geochemical point of view, monazite (LnPO4 with Ln: rare earths) is the most abundant lanthanide phosphate observed in natural samples). Such minerals appear as the major thorium source on earth, especially in several ores which contain up to 29 wt% of ThO2, 16wt% of UO2, respectively

  7. Simulation smuggling study for shielded sources of 235U, 238U, 232Th, 137Cs and 60Co by using gamma detection

    In the present time, smuggling and illicit trafficking of nuclear and radioactive materials are targeted by international groups and networks. Hundreds of smuggled nuclear and radioactive materials have been seized and currently recorded in the Illicit Trafficking Database (ITDB) of the International Atomic Energy Agency (IAEA). As a matter of fact, these materials can be used for manufacturing of dirty or Radiological Dispersal Device (RDD) or for sabotage and malicious purposes. This work deals with gamma detection of shielded sources containing natural 235U , 238U , standard 232Th and mixed 137Cs and 60Co sources by using HpGe and NaI detectors. The detection was carried out through the main characteristic γ- energies ; 185.7 KeV for 235U ,(63.3 ,1001 KeV) for 238U , (583 and 911.2 KeV) for 232Th, 661.6 KeV for 137Cs and (1173.2 and 1332.5 keV) for 60Co. The radioactive sources used are 30nCi of 232Th , 1.99 μCi of mixed 137Cs and 60Co source and uranyl nitrate crystals. These radioactive sources were separately hid (placed) in containers of different materials; aluminum (Al) , cupper (Cu) and iron (Fe) of different wall thickness; 3, 6, 9, 12, 15, 18 mm. The sources were also measured together by NaI and HpGe detector. Overlapping of different gamma transitions leads to some difficulties to identify and discriminate between the investigated γ-energies particularly with using the low resolution NaI detector. The attenuation factors (I/Io), ratio of radiation intensity with and without shield (containers), were calculated for all the investigated energies. The relationship between the attenuation factor of γ-energies and the studied thickness was depicted and discussed. It was observed, as expected, that the studied gamma transitions were attenuated by the used different thickness of Fe, Cu and Al and hardly detected especially for low energy and at 18mm thickness. Generally, it can concluded that radioactive materials of small activity can easily be smuggled

  8. Non-destructive determination of 235U, 238U, 232Th and 40K concentrations in various consumed nuts and their implication on radiation dose levels to the human body

    The naturally occurring radionuclides of 238,235,234U,232Th and 40K and their daughter products are a potential source of radiation found in food. We have determined these five radiation sources in five popular consumed nuts. We used the following neutron activation analysis reactions of 238U(n,γ)239U, 232Th(n,γ)233Th and 41K(n,γ)42K to determine 238U and 232Th and 40K, respectively. Using known activity ratios of uranium stable isotopes we determined the activity of 234,235U, while 40K was found by the determined concentrations of 41K in the nuts. While the radiation doses are small we have established a reliable methodology to determine these radionuclides in typical edible nuts. (author)

  9. Determination of committed effective doses from annual intakes of 238U and 232Th from the ingestion of cereals, fruits and vegetables by using CR-39 and LR-115 II SSNTD

    Uranium (238U) and thorium (232Th) concentrations were evaluated in different cereal, fruit and vegetable samples by using a method based on the calculation of the detection efficiencies of the emitted α-particles by CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) and measuring the resulting track densities. The influence of the soils on which the plants grow, and the fertilizers used was investigated. Total daily intakes of 238U and 232Th for a typical food basket were estimated to be 1.16 Bq x d-1 and 0.94 Bq x d-1, respectively, corresponding to a total committed effective dose of 0.27 x 10-7 Sv x d-1. Annual committed effective doses due to 238U and 232Th originated from the ingestion of different foodstuffs were evaluated for the adult members of the population by using the ICRP ingestion dose coefficients. (author)

  10. Experimental Neutron-Induced Fission Fragment Mass Yields of 232Th and 238U at Energies from 10 to 33 MeV

    Simutkin, V D; Blomgren, J; Österlund, M; Bevilacqua, R; Ryzhov, I V; Tutin, G A; Yavshits, S G; Vaishnene, L A; Onegin, M S; Meulders, J P; Prieels, R

    2013-01-01

    Development of nuclear energy applications requires data for neutron-induced reactions for actinides in a wide neutron energy range. Here we describe measurements of pre-neutron emission fission fragment mass yields of 232Th and 238U at incident neutron energies from 10 to 33 MeV. The measurements were done at the quasi-monoenergetic neutron beam of the Louvain-la-Neuve cyclotron facility CYCLONE; a multi-section twin Frisch-gridded ionization chamber was used to detect fission fragments. For the peak neutron energies at 33, 45 and 60 MeV, the details of the data analysis and the experimental results have been published before and in this work we present data analysis in the low-energy tail of the neutron energy spectra. The preliminary measurement results are compared with available experimental data and theoretical predictions.

  11. Daily intakes of 238U, 234U, 232Th, 230Th, 228Th and 226Ra in the adult population of central Poland

    Pietrzak-Flis, Z.; Rosiak, L.; Suplinska, M.M.; Chrzanowski, E.; Dembinska, S. [Central Laboratory for Radiological Protection, Konwaliowa 7, 03-194 Warsaw (Poland)

    2001-06-12

    Activity concentration of the uranium and thorium series radionuclides was determined in foodstuffs and drinking water in central Poland. Annual and daily intake for the adult population was estimated from the concentrations determined and average annual consumption of food and water. The daily intakes (in mBq) were 22.1 (238U), 26.5 (234U), 2.38 (232Th), 4.06 (230Th), 11.2 (228Th) and 42.2 (226Ra). The intake of uranium isotopes occurred mainly with water; the main intake of thorium isotopes was with animal products, vegetables, cereals and potatoes, whereas 226Ra entered mainly with animal products, cereals and vegetables. From the intake and dose coefficients, the annual effective doses for the ingested radionuclides were calculated. The annual effective dose was 5.95 {mu}Sv, of which 72.4% originated from 226Ra.

  12. A four phases model to simulate the dispersion of 226Ra, 238U and 232Th in an estuary affected by phosphate rock processing

    A numerical model to simulate the dispersion of non conservative radionuclides in tidal waters has been developed. The model includes four phases: water, suspended matter and two grain size sediment fractions. Ionic exchanges between water and the solid phases have been formulated in terms of kinetic transfer coefficients instead of distribution coefficients, because the model was developed for nonequilibrium conditions. The model simultaneously solves the shallow water hydrodynamic equations, the suspended matter dispersion equation and the four equations which give the time evolution of specific activity in each phase. The model has been applied to the Odiel river (southwest Spain), where a phosphate complex releases its wastes. It gives good results in predicting concentrations of 226Ra, 238U and 232Th in water, suspended matter, distribution coefficients and Th/U mass rations. (author)

  13. {sup 226}Ra, {sup 232}Th and {sup 40}K concentrations in igneous rocks from eastern desert, Egypt and its radiological implications

    El-Arabi, A.M. [Physics Department, Faculty of Science Qena, South Valley University (Egypt)]. E-mail: elarabi21@yahoo.com

    2007-01-15

    By applying high-resolution {gamma}-ray spectroscopic system, the various radionuclides of the granite samples have been identified quantitatively based on the characteristic spectral peaks. The radionuclides {sup 226}Ra, {sup 232}Th and {sup 40}K concentrations measured as well as radiological parameters, for 49 granite samples were calculated. This subject is important in environmental radiological protection, since granites are widely used as building and ornamental stones. The variation in concentration of radionuclides for the Um Taghir area can be classified into two regions of low and high natural radioactivity. In old granite, the measured {gamma}-ray spectra, activity concentrations were determined for {sup 226}Ra (from 2.9+/-1 to 31.8+/-6Bqkg{sup -1}), {sup 232}Th (range from 1.4+/-1 to 14.9+/-4Bqkg{sup -1}) and {sup 40}K (from 132+/-11 to 2080+/-46Bqkg{sup -1}), in younger granite {sup 226}Ra (from 8.9+/-3 to 9087+/-95Bqkg{sup -1}), {sup 232}Th (range from 9.8+/-3 to 3834+/-62Bqkg{sup -1}) and {sup 40}K (from 471+/-22 to 10230+/-101Bqkg{sup -1}). In Wadi Karim area these values were (14.0+/-4-227.0+/-15, 10.5+/-3-183.0+/-14 and 2299+/-48-7356+/-86Bqkg{sup -1}). The highest values of {sup 226}Ra, {sup 232}Th and {sup 40}K concentration (9087+/-95, 3834+/-62 and 10230+/-101Bqkg{sup -1},respectively) were observed in anomalies samples at Um Taghir region. Radium-equivalent activities (Ra{sub eq}) in addition to the internal hazard index (H{sub in}) have also been determined. In Um Taghir samples Ra{sub eq} varies between 15 and 625Bqkg{sup -1} (old granite), 144-13982Bqkg{sup -1} (younger granite) which exceeds the permitted value (370Bqkg{sup -1}) and hazard index (H{sub in}) (0.05-1.74), (0.65-62.34) which is higher than 1, the corresponding values in Wadi Karim samples were 206-685Bqkg{sup -1} and from 0.59 to 2.46, respectively. The total absorbed dose rates in air calculated from the concentrations of the three radionuclides ranged from 8 to 6187n

  14. Rare-gas yields in 238U and 232Th fission by 14MeV neutrons, measured by an emanating method

    A direct method, using emanation of rare gases by uranyle stearate and thorium stearate, has been applied to the measurement of cumulative fractional yields of certain isotopes of krypton and xenon, in the fissions of 238U and 232Th by 14MeV-neutrons. The independent yields of the same isotopes were measured previously by means of isotopic on-line separation. From these results, the widths of the mass and charge distributions, the relative chain yields, the fractional cumulative yields of certain bromine and iodine isotopes, the values of Zsub(p) the most probable charge, in the isobaric chains 87-93 and 137-142, and the elemental yields of krypton and xenon were calculated

  15. The learning of the evolution and temporary characteristics of the decay nuclei 14C, 238U, 232Th, 40K, 87Rb

    Quantum-mechanical method, which was proposing earlier for the theoretical description of the resonance scattering of the γ-quantum, was generalizing with Doppler effect using. New algorithm for the definition of the characteristic functions for the energy distribution, decay probability and decay functions elaborated. It gives possibility more precise estimate temporary characteristics of the nuclei chronometers and to define a number of the steps of the γ-absorption γ-emission in the decay process. It is give the quantum- mechanical ground of the necessity of revision of the temporary characteristics of the nuclei-chronometers. The calculations have been doing for the concrete case decay of exited nuclei 14C, 238U, 232Th, 40K, 87Rb under room temperature taking into account Doppler effect and without it. 4 refs., 1 tab., 6 figs

  16. Search for quasifission in 12C + 238U and 18O + 232Th reactions at near and sub-barrier energies

    The main motivation of this present work is to study the onset of quasifission process in the fissility region > 0.8. It was observed that angular distribution of fission fragments produced in reaction in this fissility region showed anomalously large anisotropies at subbarrier energies as compared to SSPM, implying presence of pre-equilibrium fission. Here, mass-angle correlation studies of 12C + 238U and 18O + 232Th reactions has been reported, forming same compound nucleus 250Cf (Fissility = 0.86), at similar excitation energy and angular momentum. The measurements were carried out in the energy range Ecm /Vb ∼ 0.88 - 1.1, where Ecm is the energy in centre of mass frame and Vb is the Coulomb barrier

  17. The dietary intake of 238U, 234U, 230Th, 232Th, 228Th and 226Ra from food and drinking water by inhabitants of the Walbrzych region

    Intake with food and water of the natural radionuclides of the uranium and thorium series was determined for adult population of the south-western region in Poland, where in the 1950-ies an exploration of uranium ore was conducted. Concentration of the radionuclides was determined in food products and drinking water and their annual intake was estimated on the basis of the average annual consumption. The intake of 238U, 234U and 230Th occurred mainly with water (33% to 68%), whereas the intake of 232Th, 228Th and 226Ra was mainly with vegetables, potatoes, milk and flour. From the intake and dose coefficients the annual effective doses from the ingested radionuclides were calculated. The total dose was 5.6μSv, of which 74% originated from 226Ra. (author)

  18. Daily intakes of 238U, 234U, 232Th, 230Th, 228Th and 226Ra in the adult population of central Poland

    Activity concentration of the uranium and thorium series radionuclides was determined in foodstuffs and drinking water in central Poland. Annual and daily intake for the adult population was estimated from the concentrations determined and average annual consumption of food and water. The daily intakes (in mBq) were 22.1 (238U), 26.5 (234U), 2.38 (232Th), 4.06 (230Th), 11.2 (228Th) and 42.2 (226Ra). The intake of uranium isotopes occurred mainly with water; the main intake of thorium isotopes was with animal products, vegetables, cereals and potatoes, whereas 226Ra entered mainly with animal products, cereals and vegetables. From the intake and dose coefficients, the annual effective doses for the ingested radionuclides were calculated. The annual effective dose was 5.95 μSv, of which 72.4% originated from 226Ra

  19. Determination of environmental radioactivity (238U, 232Th and 40K) and indoor natural background radiation level in Chennai city (Tamilnadu State), India.

    Babai, K S; Poongothai, S; Punniyakotti, J

    2013-01-01

    An extensive study on the determination of the natural radioactivity ((238)U, (232)Th and (40)K) levels in soil samples of Chennai city, India has been undertaken and the results of the same are compared with the levels reported in other Indian cities as well as other parts of the world. The radioactivity content in the soil samples, the absorbed dose rate, annual effective dose equivalent, radium equivalent activity, internal and external hazard indices were calculated and compared with UNSCEAR 2000 recommended values. In addition to the above, mapping of indoor natural background gamma radiation levels has been made using thermo luminescent dosemeters throughout Chennai city and the same are reported. PMID:22847868

  20. Measurement of Fragment Mass Yields in Neutron-Induced Fission of 232TH and 238U at 33, 45 and 60 Mev

    Simutkin, V. D.; Pomp, S.; Blomgren, J.; Österlund, M.; Andersson, P.; Bevilacqua, R.; Ryzhov, I. V.; Tutin, G. A.; Khlopin, V. G.; Onegin, M. S.; Vaishnene, L. A.; Meulders, J. P.; Prieels, R.

    2011-10-01

    Over the past years, a significant effort has been devoted to measurements of neutron-induced fission cross-sections at intermediate energies but there is a lack of experimental data on fission yields. Here we describe recent measurements of pre-neutron emission fragment mass distributions from intermediate energy neutron-induced fission of 232Th and 238U. The measurements have been done at the quasi-monoenergetic neutron beam of the Louvain-la-Neuve cyclotron facility CYCLONE and neutron peak energies at 32.8, 45.3 and 59.9 MeV. A multi-section Frisch-gridded ionization chamber was used as a fission fragment detector. The measurement results are compared with available experimental data. Some TALYS code modifications done to describe the experimental results are discussed.

  1. Spectroscopy study after quasi-elastic collision in the system 208Pb+232Th at an incident energy of 17 MeV per nucleon

    In the present thesis by means of a particle-particle-γ and particle-particle-neutron coincidence experiment γ and neutron spectroscopic studies after quasi-elastic collisions at incident energies far above the Coulomb barrier were performed. For the study of the γ decay by the necessary correction of the Doppler shift the possibility results to study excitations in the projectile and in the target. So in the case of 232Th beside the observation of the ground state band up to the spin 14 ℎ also a very large number of transitions from vibrational side bands. From the spectra the γ emission probabilities in dependence on the distance of closest approximation were extracted. (orig./HSI)

  2. Study of secondary neutron interactions with 232 Th, 129 I, and 127 I nuclei with the uranium assembly " QUINTA " at 2, 4, and 8 GeV deuteron beams of the JINR Nuclotron accelerator

    Adam, J. [ASCR, Prague; Chilap, V. V. [IPTP, Dubna; Furman, M. G. [Dubna, JINR; Khushvaktov, J. [Dubna, JINR; Pronskikh, V. S. [Fermilab; Solnyshkin, A. A.. [Dubna, JINR; Stegailov, V. I. [Dubna, JINR; Suchopar, M. [ASCR, Prague; Tsoupko-Sitnikov, V. M. [Dubna, JINR; Tyutyunnikov, S. I. [Dubna, JINR; Vrzalova, J.. [Dubna, JINR; Wagner, V. [ASCR, Prague; Zavorka, L. [Dubna, JINR

    2016-06-01

    The natural uranium assembly, "QUINTA", was irradiated with 2, 4, and 8 GeV deuterons. The 232 Th, 127 I, and 129 I samples have been exposed to secondary neutrons produced in the assembly at a 20-cm radial distance from the deuteron beam axis. The spectra of gamma rays emitted by the activated 232 Th, 127 I, and 129 I samples have been analyzed and several tens of product nuclei have been identified. For each of those products, neutron-induced reaction rates have been determined. The transmutation power for the 129 I samples is estimated. Experimental results were compared to those calculated with well-known stochastic and deterministic codes.

  3. The influence of the nature of soil and plant and pollution on the 238U, 232Th, 222Rn and 220Rn concentrations in various natural honey samples using nuclear track detectors: Impact on the adult consumers

    M A Misdaq; A Mortassim

    2009-11-01

    238U and 232Th concentrations as well as 222Rn and 220Rn -activities per unit volume were measured in various natural honey samples collected from different regions in Morocco using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). These radionuclides were also measured in soils, plant flowers and nectar solutions corresponding to the honey samples studied. In addition, these radionuclides were measured in different imported honey samples. The measured 238U, 232Th, 222Rn and 220Rn concentrations ranged from (1.5 ± 0.1) mBq kg-1 to (10.6 ± 0.6) mBq kg-1, (1.1 ± 0.1) mBq kg-1 to (4.2 ± 0.2) mBq kg-1 , (1.5 ± 0.1) Bq kg-1 to (10.6 ± 0.6) Bq kg-1 and (1.1 ± 0.1) Bq kg-1 to (4.2 ± 0.2) Bq kg-1 for the honey samples studied, respectively. Annual 238U, 232Th and 222Rn intakes by Moroccan adults from the consumption of honey were assessed. The influence of the nature of soil and plant on the 238U and 232Th contents of the studied honey samples was investigated. These measurements were completed by an investigation of the 238U and 232 Th transfer between soils and plant flowers and that between plant flowers and honey, and also by the investigation of the influence of pollution due to different material dusts on 238U, 232Th and 222Rn in the honey samples studied. Committed equivalent doses due to the annual intake of 238U, 232Th and 222Rn were evaluated in the organs of adult members of the Moroccan rural population from the ingestion of the honey samples. The maximum total committed effective dose due to 238U, 232Th and 222Rn from the ingestion of natural honey by the Moroccan rural population was found to be equal to 0.64 Sv y-1 .

  4. Separation and quantification of 238U, 232Th and rare earths in monazite samples by ion chromatography coupled with on-line flow scintillation detector

    An alternative procedure has been described for efficient separation and quantitative determination of uranium (U), thorium (Th) and rare earth elements (REEs) in monazite mineral by high performance ion chromatographic system (IC). Different variables affecting the distribution coefficient, the retention and hence separation efficiency such as eluent flow rate and concentrations of HCl and ammonium sulfate (NH4)2SO4 containing the mobile phase were studied. The developed separation protocol of U, Th and REEs was optimized using an Ion Pac CS5 separation column followed by post-column derivatization reaction with Arsenaso III and UV-VIS spectrophotometeric detection. Comparative evaluation of U, Th and REEs concentration in monazite mineral was demonstrated using two different on-line detection modes including flow through cell scintillation detector (FSD) and UV-VIS spectrophotometer. Response of the FSD was found to be linear over the full range of activities investigated (4-100 Bq). The lower limits of detection (LLD) for the investigated radionuclides were 3.0±0.1 Bq for 238U and 6.0±0.1 Bq for 232Th. The detection of 238U and 232Th by FSD shows good agreement with the corresponding determination by UV-VIS spectrophotometer. The content of ThO2 and U3O8 in monazite sample were found to be 4.7±0.1% and 0.42±0.04% using UV-VIS detector and 4.3±0.1% and 0.45±0.1% using FSD, respectively

  5. The use of fission foils for plasma neutron diagnostics

    Commonly used fission foil materials have been examined for their application to plasma diagnostics as activation foils. Such foils have been used extensively in the past for fission reactor dosiemetry. They have very well known fission cross sections, and in most cases the fission yields are reasonably well known. The materials included in this study are 226Ra, 228Th, 232Th, 231Pa, 233U, 235U, 238U, 237Np, 238Pu, and 239Pu. Of these materials 232Th, 235U, and 238U are considered to be very good candidates for this application. The others have been eliminated because of high background radioactivity, impurities which present high backgrounds, or lack of knowledge about yield distribution of fission products. Production cross sections for fission products in the vicinity of the yield maxima (A = 85 - 101, 133 143) have been calculated from known fission cross sections and independent or cumulative yields at thermal energies (where applicable) and 14 MeV. Recent measurements at 2.5 MeV are also included. For one foil (232Th) results for 3 MeV and 11 MeV are also available. The decay schemes of the more prominent fission products have been thoroughly studied and good measurement precision should result from their use

  6. Transfer Rates of 238U and 232Th for E. globulus, A. mearnsii, H. filipendula and Hazardous Effects of the Usage of Medicinal Plants From Around Gold Mine Dump Environs

    Victor M. Tshivhase

    2015-12-01

    Full Text Available Medicinal plant consumption can be a source of human exposure to radioactive elements such as 238U and 232Th, which can lead to internal radiation doses. The uptake of 238U and 232Th from soils to the leaf samples of three different medicinal plant species (Eucalyptus globulus, Acacia mearnsii and Hyparrhenia filipendula from the purlieu of the Princess gold mine dump, an abandoned contaminated tailings storage site (TSS, located at longitude 27°55′00″E and latitude 26°09′30″S in Davidsonville (Roodepoort, west of Johannesburg, South Africa was measured. This was done using ICP-MS spectrometry and substantial differences were observed in the soil-plant transfer factor (TF values between these radionuclides. The plant species E. globulus exhibited the highest uptake of 238U, with an average TF of 3.97, while that of H. filipendula was 0.01 and the lowest TF of 0.15 × 10−2 was measured for A. mearnsii. However, in the case of 232Th, the highest average TF was observed for A. mearnsii (0.29, followed by E. globulus (0.10 and lowest was measured for H. filipendula (0.27 × 10−2. The ratio of TF average value i.e., 238U to 232Th in the soil-plant leaves was 38.05 for E. globulus, 0.01 for A. mearnsii and 4.38 for H. filipendula.

  7. Use of LabSOCS for determination of specific concentrations of {sup 40}K, {sup 238}U and {sup 232}Th in fertilizer samples; Uso de LabSOCS no calculo da eficiencia de detecao para determinacao da concentracao especifica de {sup 40}K, {sup 238}U e {sup 232}Th em amostras de fertilizantes

    Garcez, Ricardo Washington Dutra; Lopes, Jose Marques; Silva, Ademir Xavier da, E-mail: rgarcez@con.ufrj.br, E-mail: marqueslopez@yahoo.com.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Domingues, Alessandro Mariano; Lima, Marco Frota, E-mail: slessandrodomingues@fisica.if.uff.br, E-mail: marcofrotalima@yahoo.com.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Biologia

    2015-07-01

    Use of fertilizer is an established practice worldwide to promote agricultural productivity increased without increasing the planted area, resulting in native forests protection and increase of the food availability. Some kinds of fertilizer have in their chemical composition some radionuclides due the origin of its feedstock, such as {sup 238}U, the {sup 232}Th, and their descendants, beyond {sup 40}K. Knowledge of the radioactivity levels in the environment is great importance to know the gamma radiation dose that the human being is exposed. For identification and quantitation of radionuclides, it was used gamma spectrometry where HPGe detector was used to obtain the spectra, and LabSOCS software for calculating the detection efficiency for each energy. The values of {sup 232}Th specific concentrations ranged from 4.1 to 368.1 Bq.Kg{sup -1} , the values of {sup 238}U specific concentrations ranged from 16.0 to 647.7 Bq.Kg{sup -1} and {sup 40}K specific concentrations ranged from 19.1 to 12713 Bq.Kg{sup -1} . Concentrations of values are consistent with those found in literature. (author)

  8. Assessment of sedimentation rate based on disequilibrium in the {sup 232}Th decay series in an artificial pond downstream a former uranium mine

    Reyss, J.L. [Laboratoire des Sciences du Climat et de l' Environnement - LSCE/IPSL, Unite Mixte de Recherche 8212 CEA, CNRS, UVSQ, F-91198 Gif-sur-Yvette Cedex (France); Mangeret, A.; Courbet, C.; Saadi, Z.; Guillevic, J. [Institut de Radioprotection et de Surete Nucleaire (IRSN), BP 17, 92262 Fontenay aux Roses (France); Thouvenot, A. [LMGE, UMR CNRS 6023, Lab Microorganismes Genome et Environnement, 63 177 Aubiere (France)

    2014-07-01

    In rivers and lakes, sediment dynamics are very difficult to quantify by field measurements as well as by modeling studies (Olley et al. 1997 WRR 33, 1319-1326). The well-known {sup 210}Pb excess method (Appleby 2000 Limnology 59-S.1, 1-14; Perga et al. 2010 Limnol. and Ocean. 55, 803-816) cannot be used for quantifying sedimentation rates over granitic catchments as large amounts of {sup 210}Pb produced by granite weathering tend to dilute the atmospheric {sup 210}Pb. The knowledge of sedimentation rates in lakes is however very important for understanding the geochemical mechanisms involved in contaminant scavenging and remobilization at the sediment-water interface (SWI). Moreover, these measurements are crucial for developing solute transport models, especially for radionuclides and metals in pore waters and through the SWI. In order to overcome these issues, this study focuses on an artificial pound located in a granitic catchment, down-gradient from a former uranium mining site that ceased operations at the beginning of the 80's (Guillevic and Reyss 2011 ICRER 2011). Sediment sampling was carried out in this artificial lake with an UWITEC{sup R} hand corer. All the samples were dried and the activities of artificial and natural radionuclides were measured by gamma spectrometry, at the Underground Laboratory of Modane and alpha spectrometry after radiochemical purification. The profile of {sup 210}Pb activities in the sediment increased with depth in the core and did not allow to distinguish the atmospheric {sup 210}Pb from the {sup 210}Pb produced by watering processes in this uranium enriched environment. Another method for quantifying sediment accumulation rates is therefore proposed here using the disequilibrium between {sup 228}Ra (half-life of 5.75 years) and {sup 232}Th, the parent isotope. The excess of {sup 228}Ra over its respective parent {sup 232}Th has already been demonstrated by (Olley et al. 1997 WRR 33, 1319-1326) in river and lake

  9. 238U series isotopes and 232Th in carbonates and black shales from the Lesser Himalaya: implications to dissolved uranium abundances in Ganga-Indus source waters

    238U and 232Th concentrations and the extent of 238U-234U-230Th radioactive equilibrium have been measured in a suite of Precambrian carbonates and black shales from the Lesser Himalaya. These measurements were made to determine their abundances in these deposits, their contributions to dissolved uranium budget of the headwaters of the Ganga and the Indus in the Himalaya and to assess the impact of weathering on 238U-234U-230Th radioactive equilibrium in them. 238U concentrations in Precambrian carbonates range from 0.06 to 2.07 μg g-1. The 'mean' U/Ca in these carbonates is 2.9 ng U mg-1 Ca. This ratio, coupled with the assumption that all Ca in the Ganga-Indus headwaters is of carbonate origin and that U and Ca behave conservatively in rivers after their release from carbonates, provides an upper limit on the U contribution from these carbonates, to be a few percent of dissolved uranium in rivers. There are, however, a few streams with low uranium concentrations, for which the carbonate contribution could be much higher. These results suggest that Precambrian carbonates make only minor contributions to the uranium budget of the Ganga-Indus headwaters in the Himalaya on a basin wide scale, however, they could be important for particular streams. Similar estimates of silicate contribution to uranium budget of these rivers using U/Na in silicates and Na* (Na corrected for cyclic and halite contributions) in river waters show that silicates can contribute significantly (∼40% on average) to their U balance. If, however, much of the uranium in these silicates is associated with weathering resistant minerals, then the estimated silicate uranium component would be upper limits. Uranium concentration in black shales averages about 37 μg g-1. Based on this concentration, supply of U from at least ∼50 mg of black shales per liter of river water is needed to balance the average river water U concentration, 1.7 μg L-1 in the Ganga-Indus headwaters. Data on the

  10. Assessment of natural radionuclides concentration from 238U and 232Th series in Virginia and Burley varieties of Nicotiana tabacum L

    Brazil is the largest exporter and second largest producer of tobacco worldwide, according to the crop production of 2013/2014. The tobacco plant (Nicotiana tabacum L.) is used to manufacture all derivatives and the chemical composition of the resulting tobacco products varies with the type of tobacco leaves, how they are grown, the region where they are cultivated, the characteristics of preparation (compression, filter and paper) and the temperature variations resulting from the incomplete combustion of tobacco. Tobacco products are extensively used throughout the world, and the most consumed are cigarettes, cigars and narghile. The damaging effects that these products cause to human health are discussed globally, and many surveys are performed with the aim of relating the use of these products with various illnesses. There is a lack of information about the radiological characterization of the tobacco plant both in international and Brazilian literature. The objective of this study was to determine the concentration of radionuclides 238U, 234U, 230Th, 22'6Ra, 210Pb and 210Po, members from the 238U decay series, and the radionuclides 232Th and 228Ra members of the 232Th decay series in the varieties Burley and Virginia, which are the most cultivated in Brazil. Plants from these varieties were cultivated in pots with organic substrate and fertilizer and also acquired from the producers and analyzed by alpha spectrometry for U and Th isotopes and 210Po determination, and gross alpha and beta counting, 228Ra, 226Ra and 210Pb determination. The whole plant, from both places, was analyzed; root, stem, leaves, as well as the organic substrate, the fertilizers, and the soil. The results for U and Th isotopes presented values below the detection limits of the methods to the leaves and stems of all plants analyzed, with measurable results only in roots, soil, and substrate. The radionuclides 226Ra, 228Ra, 210Pb, and 210Po, were determined in most parts of the plants