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Sample records for 237np 231pa ionizatsionnykh

  1. 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

  2. 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)

  3. 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.)

  4. 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)

  5. 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)

  6. 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)

  7. 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)

  8. 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

  9. 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)

  10. 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

  11. 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)

  12. 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)

  13. 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

  14. 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...

  15. 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

  16. 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.)

  17. 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.

  18. 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

  19. 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 $\

  20. 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

  1. 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)

  2. 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)

  3. 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)

  4. 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, ...

  5. (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.

  6. 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)

  7. 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)

  8. 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)

  9. 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)

  10. 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.

  11. 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)

  12. 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

  13. 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)

  14. 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

  15. 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

  16. 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.

  17. 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.)

  18. 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

  19. 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

  20. 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)

  1. 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.)

  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. 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

  5. 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

  6. 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)

  7. 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

  8. 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)

  9. 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)

  10. 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)

  11. 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

  12. 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)

  13. 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)

  14. 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

  15. 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.

  16. 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

  17. 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)

  18. 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.).

  19. 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

  20. 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)

  1. 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)

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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)

  7. 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...

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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)

  14. 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

  15. 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

  16. 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)

  17. 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

  18. 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.

  19. 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)

  20. 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

  1. 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

  2. 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)

  3. 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...

  4. 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

  5. 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)

  6. 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.

  7. 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)

  8. 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

  9. 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...

  10. 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.))

  11. 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...

  12. 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

  13. 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

  14. 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)

  15. 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。

  16. 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

  17. 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

  18. 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

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

    A first series of fission cross-section measurements for incident neutron energies between 0.6 and 3.4 MeV has confirmed a first chance threshold value around 1b. In contrast to our findings for the fission cross-section in 233Pa, both the direct and the surrogate cross-section data lead to the same result. This seems to support the assumption, that only in cases, where ingoing and outgoing particle are similar, particle-transfer reactions give results that are in agreement with those obtained from direct compound nuclear reactions

  20. Post-Irradiation Examination of 237Np Targets for 238Pu Production

    Morris, Robert Noel [ORNL; Baldwin, Charles A [ORNL; Hobbs, Randy W [ORNL; Schmidlin, Joshua E [ORNL

    2015-01-01

    Oak Ridge National Laboratory is recovering the US 238Pu production capability and the first step in the process has been to evaluate the performance of a 237Np target cermet pellet encased in an aluminum clad. The process proceeded in 3 steps; the first step was to irradiate capsules of single pellets composed of NpO2 and aluminum power to examine their shrinkage and gas release. These pellets were formed by compressing sintered NpO2 and aluminum powder in a die at high pressure followed by sintering in a vacuum furnace. Three temperatures were chosen for sintering the solution precipitated NpO2 power used for pellet fabrication. The second step was to irradiate partial targets composed of 8 pellets in a semi-prototypical arrangement at the two best performing sintering temperatures to determine which temperature gave a pellet that performed the best under the actual planned irradiation conditions. The third step was to irradiate ~50 pellets in an actual target configuration at design irradiation conditions to assess pellet shrinkage and gas release, target heat transfer, and dimensional stability. The higher sintering temperature appeared to offer the best performance after one cycle of irradiation by having the least shrinkage, thus keeping the heat transfer gap between the pellets and clad small minimizing the pellet operating temperature. The final result of the testing was a target that can meet the initial production goals, satisfy the reactor safety requirements, and can be fabricated in production quantities. The current focus of the program is to verify that the target can be remotely dissembled, the pellets dissolved, and the 238Pu recovered. Tests are being conducted to examine these concerns and to compare results to code predictions. Once the performance of the full length targets has been quantified, the pellet 237Np loading will be revisited to determine if it can be increased to increase 238Pu production.

  1. Speciation of 241Am molecular compounds through 237Np Moessbauer and 241Am XPS spectroscopy

    Light actinides (U to Am) can be found in several oxidation states from (II) to (VII) in the molecular form or in the condensed matter state. The large variety of oxidation states is usually attributed to the contribution of the 5f states to the valence orbitals. For the heavier actinides, for which the 5f electrons are non bonding, the actinides become rare-earth like with a smaller number of oxidation states (II and III). However it is still not understood what really decides on the stability of a given oxidation state, and how it is depending on the chemical environment (coordination sphere, nature of the counter-anion, etc). This work shows how Moessbauer spectroscopy and 4f photoelectron spectroscopy (XPS) can contribute to progress in the understanding of the electronic structure of the actinide, especially for Am compounds Moessbauer reverse experiments were undertaken to show in what manner the electronic structure of the Am is preserved during the decay process (oxidation state stability). The result of XPS measurements shows that it is possible to correlate the 4f binding energy of the Am to the charge at the actinide core. The obtained results are somewhat surprising. The formal oxidation state (V) is 'less oxidised' than expected. Some Am(III) have less electron density (that means are more ionic) than americyl (V) hydroxide or carbonate. The reason for these surprisingly results comes from the 'Am=O' multiple bond system which reduces dramatically the charge at the actinide by a pi-donation mechanism. The evolution of the 4f binding energy of the Am species does not follow the oxidation state order. Theoretical DFT calculation were done on Am(V) compounds for qualitative electronic modeling. (authors)

  2. Sorption of 231Pa on silica and the effect of humic acid

    Sorption of protactinium on silica colloids was studied in the pH range of 1 to 12 in NaClO4 medium using radiotracer technique. Silica was characterized using X-ray diffraction, light scattering and surface area measurements. The point of zero charge for silica colloids was about pH 2. The sorption of protactinium was about 98% in the pH range of 3 to 9 and was lower (70-80 %) below pH 3 and above pH 9. The quantitative sorption in the pH range 3 to 9 could be explained by surface complexation model. The reduction in sorption was attributed to electrostatic repulsion as the fraction of protactinium exists as cationic species at pH ≤ 2 and anionic species above pH 9. There was reduction in the sorption of protactinium in the presence of humic acid below pH 2 and above pH 10. Sorption of protactinium on silica in presence of 0.05M HF was about 99% between pH 3 to 8 and below 30% in the low and high pH region. Isotherm study revealed an exponential decrease in protactinium activity in solution with increase in silica. (author)

  3. Measurements of periods, relative abundances and absolute yields of delayed neutrons from fast neutron induced fission of {sup 237}Np

    Piksaikine, V. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-03-01

    The experimental method for measurements of the delayed neutron yields and period is presented. The preliminary results of the total yield, relative abundances and periods are shown comparing with the previously reported values. (J.P.N.)

  4. Speciation of {sup 241}Am molecular compounds through {sup 237}Np Moessbauer and {sup 241}Am XPS spectroscopy

    Fouchard, S.; Gouder, T.; Colineau, E.; Wastin, F.; Rebizant, J.; Simoni, E.; Guillaumont, D.; Meyer, D

    2004-07-01

    Light actinides (U to Am) can be found in several oxidation states from (II) to (VII) in the molecular form or in the condensed matter state. The large variety of oxidation states is usually attributed to the contribution of the 5f states to the valence orbitals. For the heavier actinides, for which the 5f electrons are non bonding, the actinides become rare-earth like with a smaller number of oxidation states (II and III). However it is still not understood what really decides on the stability of a given oxidation state, and how it is depending on the chemical environment (coordination sphere, nature of the counter-anion, etc). This work shows how Moessbauer spectroscopy and 4f photoelectron spectroscopy (XPS) can contribute to progress in the understanding of the electronic structure of the actinide, especially for Am compounds Moessbauer reverse experiments were undertaken to show in what manner the electronic structure of the Am is preserved during the decay process (oxidation state stability). The result of XPS measurements shows that it is possible to correlate the 4f binding energy of the Am to the charge at the actinide core. The obtained results are somewhat surprising. The formal oxidation state (V) is 'less oxidised' than expected. Some Am(III) have less electron density (that means are more ionic) than americyl (V) hydroxide or carbonate. The reason for these surprisingly results comes from the 'Am=O' multiple bond system which reduces dramatically the charge at the actinide by a pi-donation mechanism. The evolution of the 4f binding energy of the Am species does not follow the oxidation state order. Theoretical DFT calculation were done on Am(V) compounds for qualitative electronic modeling. (authors)

  5. Migration of the radionuclides 99Tc, 237Np, 238Pu and 241Am in the caprock of the Gorleben repository

    31 different combinations of sediments with groundwaters (sediment-groundwater-systems) formed the basis of the experiments to determine sorption data and sorption mechanisms of radionuclides in selected acquifer systems with loose rock samples taken from shafts 1 and 2. The waters were selected on the basis of pore water analyses. For cohesive materials from which no pore water could be extracted, groundwaters from the horizon below and above were chosen. (orig.)

  6. Transmutation study of 237Np in energy + transmutation setup using 1.6 GeV deuteron-beam

    In this paper, the results of the measurement of cross sections of (n, γ) and (n, f) reactions of long lived fission fragment, Np237 have been presented in the mixed neutron environment of the E + T set up

  7. 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)

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

    Adam, Jindřich

    2007-01-01

    Roč. 68, č. 2 (2007), s. 201-212. ISSN 0304-4289 R&D Projects: GA MŠk 1P04LA213 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutro production Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.383, year: 2007

  9. Radiochemical method for the simultaneous determination of 233U, 236U, 237Np, 236Pu, 238Pu, and 239Pu in biological materials

    A radiochemical method has been developed for the determination of multiple isotopes of uranium, neptunium, and plutonium in biological materials. The elements are separated from the other sample constituents and from each other by anion exchange in halide media. Their recoveries are monitored by isotopic diluents. The amounts of the analyte and diluent isotopes of each element are measured alpha spectrometrically. The interelemental separation factors are generally greater than 102, and the recovery of each element ranges from 60% to 90%. 4 references, 1 table

  10. 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

  11. First results studying the transmutation of 129I, 237Np, 238Pu, and 239Pu in the irradiation of an extended natU/Pb-assembly with 2.52 GeV deuterons

    Krivopustov, M. I.; Pavljuk, A. V.; Kovalenko, A.D.; Mariin, I.I.; Elishev, A.F.; Adam, Jindřich; Kovalík, Alojz; Batusov, Yu, A.; Kalinnikov, V. G.; Brudanin, V. B.; Čaloun, Pavel; Tsoupko-Sitnikov, V. M.; Solnyshkin, A. A.; Stegailov, V. I.; Gerbish, Sh.; Svoboda, Ondřej; Dubnická, Z.; Kala, M.; Kloc, M.; Krása, Antonín; Kugler, Andrej; Majerle, Mitja; Wagner, Vladimír; Brandt, R.; Westmeier, W.; Robotham, H.; Siemon, K.; Bielewicz, M.; Kilim, S.; Szuta, M.; Strugalska-Gola, E.; Wojeciechowski, A.; Hashemi-Nezhad, R. S.; Manolopoulou, M.; Fragopolou, M.; Stoulos, S.; Zamani-Valasiadou, M.; Jokic, S.; Katovsky, K.; Schastny, O.; Zhuk, I. V.; Potapenko, A.S.; Safronova, A.A.; Lukashevich, Zh.A.; Voronko, V.A.; Sotnikov, V.V.; Sidorenko, V.V.; Ensinger, W.; Severin, H.D.; Batsev, S.; Kostov, L.; Protokhristov, Kh.; Stoyanov, Ch,.; Yordanov, O.; Zhivkov, P.K.; Kumar, A.V.; Sharma, M.; Khilmanovich, A.M.; Marcinkevich, B.A.; Korneev, S.V.; Damdinsuren, Ts.; Togoo, Ts.; Kumawat, H.

    2009-01-01

    Roč. 279, č. 2 (2009), s. 567-584. ISSN 0236-5731 R&D Projects: GA AV ČR IAA100480803; GA MŠk LC07050 Institutional research plan: CEZ:AV0Z10480505 Keywords : MCNPX. * GeV Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.631, year: 2009

  12. 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)

  13. Design study of long-life PWR using thorium cycle

    Subkhi, Moh. Nurul; Su'ud, Zaki; Waris, Abdul

    2012-06-01

    Design study of long-life Pressurized Water Reactor (PWR) using thorium cycle has been performed. Thorium cycle in general has higher conversion ratio in the thermal spectrum domain than uranium cycle. Cell calculation, Burn-up and multigroup diffusion calculation was performed by PIJ-CITATION-SRAC code using libraries based on JENDL 3.2. The neutronic analysis result of infinite cell calculation shows that 231Pa better than 237Np as burnable poisons in thorium fuel system. Thorium oxide system with 8% 233U enrichment and 7.6˜ 8% 231Pa is the most suitable fuel for small-long life PWR core because it gives reactivity swing less than 1% Δk/k and longer burn up period (more than 20 year). By using this result, small long-life PWR core can be designed for long time operation with reduced excess reactivity as low as 0.53% Δk/k and reduced power peaking during its operation.

  14. A study of the generation of 232U in UO2 and MOX fuels

    To clarify the generation pathway of 232U, an important nuclide for dose evaluation at various stages in the reuse of uranium, concentrations of 232U generated through various pathways were evaluated for UO2 and mixed oxide (MOX) fuels. Burnup calculation was conducted with ORIGEN2.2 code adopting ORLIBJ40 library, a set of cross-section libraries based on JENDL-4.0. It was found that differences in 232U concentrations in UO2 and MOX fuels mainly arise from differences in the initial compositions of 234U, 235U, and 236U. It was also found that the contribution of plutonium and americium isotopes in MOX fuels is small compared with that of uranium isotopes. The results clarified that the capture cross sections of 230Th, 231Pa, 235U, and 236U, as well as the (n,2n) cross sections of 237Np and 238U, have a large effect on the generation of 232U. Additional investigation showed that 232U concentration is strongly affected not only by time after irradiation but also by time before irradiation. (author)

  15. Characterization of actinide physics specimens for the US/UK joint experiment in the Dounreay Prototype Fast Reactor

    The United States and the United Kingdom are engaged in a joint research program in which samples of the higher actinides are irradiated in the Dounreay Prototype Fast Reactor in Scotland. The purpose of the porogram is (1) to study the materials behavior of selected higher actinide fuels and (2) to determine the integral cross sections of a wide variety of the higher actinide isotopes. Samples of the actinides are incorporated in fuel pins inserted in the core. For the fuel study, the actinides selected are 241Am and 244Cm in the form of Am2O3, Cm2O3, and Am6Cm(RE)7O21, where (RE) represents a mixture of lanthanides. For the cross-section determinations, the samples are milligram quantities of actinide oxides of 248Cm, 246Cm, 244Cm, 243Cm, 243Am, 241Am, 244Pu, 242Pu, 241Pu, 240Pu, 239Pu, 238Pu, 237Np, 238U, 236U, 235U, 234U, 233U, 232Th, 230Th, and 231Pa encapsulated in vanadium. Coincident with the irradiations, neutron flux and energy spectral measurements are made with vanadium-encapsulated dosimeter materials located within the same fuel pins

  16. 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

  17. Preparation of actinide specimens for the US/UK joint experiment in the Dounreay Prototype Fast Reactor

    A joint research program involving the United States and the United Kingdom was initiated about four years ago for the purpose of studying the fuel behavior of higher actinides using in-core irradiation in the fast reactor at Dounreay, Scotland. Simultaneously, determination of integral cross sections of a wide variety of higher actinide isotopes (physics specimens) was proposed. Coincidental neutron flux and energy spectral measurements were to be made using vanadium encapsulated dosimetry materials in the immediate region of the fuel pellets and physics samples. The higher actinide samples chosen for the fuel study were 241Am and 244Cm in the forms of Am2O3, Cm2O3, and Am6Cm(RE)7O21, where (RE) represents a mixture of lanthanides. Milligram quantities of actinide oxides of 248Cm, 246Cm, 244Cm, 243Cm, 243Am, 241Am, 244Pu, 242Pu, 241Pu, 240Pu, 239Pu, 238Pu, 237Np, 238U, 236U, 235U, 234U, 233U, 232Th, 230Th, and 231Pa were encapsulated to obtain nuclear cross section and reaction rate data for these materials

  18. Application of the Spanish methodological approach for biosphere assessment to a generic high-level waste disposal site.

    Agüero, A; Pinedo, P; Simón, I; Cancio, D; Moraleda, M; Trueba, C; Pérez-Sánchez, D

    2008-09-15

    A methodological approach which includes conceptual developments, methodological aspects and software tools have been developed in the Spanish context, based on the BIOMASS "Reference Biospheres Methodology". The biosphere assessments have to be undertaken with the aim of demonstrating compliance with principles and regulations established to limit the possible radiological impact of radioactive waste disposals on human health and on the environment, and to ensure that future generations will not be exposed to higher radiation levels than those that would be acceptable today. The biosphere in the context of high-level waste disposal is defined as the collection of various radionuclide transfer pathways that may result in releases into the surface environment, transport within and between the biosphere receptors, exposure of humans and biota, and the doses/risks associated with such exposures. The assessments need to take into account the complexity of the biosphere, the nature of the radionuclides released and the long timescales considered. It is also necessary to make assumptions related to the habits and lifestyle of the exposed population, human activities in the long term and possible modifications of the biosphere. A summary on the Spanish methodological approach for biosphere assessment are presented here as well as its application in a Spanish generic case study. A reference scenario has been developed based on current conditions at a site located in Central-West Spain, to indicate the potential impact to the actual population. In addition, environmental change has been considered qualitatively through the use of interaction matrices and transition diagrams. Unit source terms of (36)Cl, (79)Se, (99)Tc, (129)I, (135)Cs, (226)Ra, (231)Pa, (238)U, (237)Np and (239)Pu have been taken. Two exposure groups of infants and adults have been chosen for dose calculations. Results are presented and their robustness is evaluated through the use of uncertainty and

  19. Analysis of trace neptunium in the vicinity of underground nuclear tests at the Nevada National Security Site

    A high sensitivity analytical method for 237Np analysis was developed and applied to groundwater samples from the Nevada National Security Site (NNSS) using short-lived 239Np as a yield tracer and HR magnetic sector ICP-MS. The 237Np concentrations in the vicinity of the Almendro, Cambric, Dalhart, Cheshire, and Chancellor underground nuclear test locations range from <4 × 10−4 to 2.6 mBq/L (6 × 10−17–4.2 × 10−13 mol/L). All measured 237Np concentrations are well below the drinking water maximum contaminant level for alpha emitters identified by the U.S. EPA (560 mBq/L). Nevertheless, 237Np remains an important indicator for radionuclide transport rates at the NNSS. Retardation factor ratios were used to compare the mobility of 237Np to that of other radionuclides. The results suggest that 237Np is less mobile than tritium and other non-sorbing radionuclides (14C, 36Cl, 99Tc and 129I) as expected. Surprisingly, 237Np and plutonium (239,240Pu) retardation factors are very similar. It is possible that Np(IV) exists under mildly reducing groundwater conditions and exhibits a retardation behavior that is comparable to Pu(IV). Independent of the underlying process, 237Np is migrating downgradient from NNSS underground nuclear tests at very low but measureable concentrations. - Highlights: • A high sensitivity analytical method for 237Np analysis in groundwater was developed. • Groundwater samples from the Nevada National Security Site (NNSS) were analyzed. • 237Np concentrations were well below the EPA maximum contaminant level in drinking water. • 237Np is less mobile than 3H and other non-sorbing radionuclides. • 237Np and Pu apparent retardation factors are similar

  20. Np-237 in peat and lichen in Finland

    Salminen, S.; Paatero, J.; Roos, Per;

    2009-01-01

    Activity concentrations of 237Np in peat and lichen samples in Finland were determined and contributions from nuclear weapons testing in 1950–1960s and the Chernobyl accident were estimated. 237Np was determined with ICP-MS using 235Np as a tracer. Activity concentrations of 237Np in peat samples...... varied between 1.98 ± 0.05 and 14.1 ± 0.3 mBq/m2. The contribution from the Chernobyl accident to the total 237Np deposition in peat was 0.1–13%, the Chernobyl-derived fraction of total 237Np in peat being much lower than the previously determined corresponding Chernobyl-derived fractions of 239+240Pu...

  1. Inorganic, radioisotopic and organic analysis of 241-AP-101 tank waste

    Battelle received five samples from Hanford waste tank 241-AP-101, taken at five different depths within the tank. No visible solids or organic layer were observed in the individual samples. Individual sample densities were measured, then the five samples were mixed together to provide a single composite. The composite was homogenized and representative sub-samples taken for inorganic, radioisotopic, and organic analysis. All analyses were performed on triplicate sub-samples of the composite material. The sample composite did not contain visible solids or an organic layer. A subsample held at 10 C for seven days formed no visible solids. The characterization of the 241-AP-101 composite samples included: (1) Inductively-coupled plasma spectrometry for Ag, Al, Ba, Bi, Ca, Cd, Cr, Cu, Fe, K, La, Mg, Mn, Na, Nd, Ni, P, Pb, Pd, Ru, Rh, Si, Sr, Ti, U, Zn, and Zr (Note: Although not specified in the test plan, As, B, Be, Co, Li, Mo, Sb, Se, Sn, Tl, V, W, and Y were also measured and reported for information only) (2) Radioisotopic analyses for total alpha and total beta activities, 3H, 14C, 60Co, 79Se, 90Sr, 99Tc as pertechnetate, 106Ru/Rh, 125Sb, 134Cs, 137Cs, 152Eu, 154Eu, 155Eu, 238Pu, 239+240Pu, 241Am, 242Cm, and 243+244Cm; (3) Inductively-coupled plasma mass spectrometry for 237Np, 239Pu, 240Pu, 99Tc, 126Sn, 129I, 231Pa, 233U, 234U, 235U, 236U, 238U, 241AMU, 242AMU, 243AMU, As, B, Be, Ce, Co, Cs, Eu, I, Li, Mo, Pr, Rb, Sb, Se, Ta, Te, Th, Tl, V, and W; (4) total U by kinetic phosphorescence analysis; (5) Ion chromatography for Cl, F, NO2, NO3, PO4, SO4, acetate, formate, oxalate, and citrate; (6) Density, inorganic carbon and organic carbon by two different methods, mercury, free hydroxide, ammonia, and cyanide. The 241-AP-101 composite met all contract limits (molar ratio of analyte to sodium or ratio of becquerels of analyte to moles of sodium) defined in Specification 7 for Envelope A. Except for a few cases, the characterization results met or surpassed the

  2. Inorganic, radioisotopic and organic analysis of 241-AP-101 tank waste

    SK Fiskum; PR Bredt; JA Campbell; LR Greenwood; OT Farmer; GJ Lumetta; GM Mong; RT Ratner; CZ Soderquist; RG Swoboda; MW Urie; JJ Wagner

    2000-06-28

    Battelle received five samples from Hanford waste tank 241-AP-101, taken at five different depths within the tank. No visible solids or organic layer were observed in the individual samples. Individual sample densities were measured, then the five samples were mixed together to provide a single composite. The composite was homogenized and representative sub-samples taken for inorganic, radioisotopic, and organic analysis. All analyses were performed on triplicate sub-samples of the composite material. The sample composite did not contain visible solids or an organic layer. A subsample held at 10 C for seven days formed no visible solids. The characterization of the 241-AP-101 composite samples included: (1) Inductively-coupled plasma spectrometry for Ag, Al, Ba, Bi, Ca, Cd, Cr, Cu, Fe, K, La, Mg, Mn, Na, Nd, Ni, P, Pb, Pd, Ru, Rh, Si, Sr, Ti, U, Zn, and Zr (Note: Although not specified in the test plan, As, B, Be, Co, Li, Mo, Sb, Se, Sn, Tl, V, W, and Y were also measured and reported for information only) (2) Radioisotopic analyses for total alpha and total beta activities, {sup 3}H, {sup 14}C, {sup 60}Co, {sup 79}Se, {sup 90}Sr, {sup 99}Tc as pertechnetate, {sup 106}Ru/Rh, {sup 125}Sb, {sup 134}Cs, {sup 137}Cs, {sup 152}Eu, {sup 154}Eu, {sup 155}Eu, {sup 238}Pu, {sup 239+240}Pu, {sup 241}Am, {sup 242}Cm, and {sup 243+244}Cm; (3) Inductively-coupled plasma mass spectrometry for {sup 237}Np, {sup 239}Pu, {sup 240}Pu, {sup 99}Tc, {sup 126}Sn, {sup 129}I, {sup 231}Pa, {sup 233}U, {sup 234}U, {sup 235}U, {sup 236}U, {sup 238}U, {sup 241}AMU, {sup 242}AMU, {sup 243}AMU, As, B, Be, Ce, Co, Cs, Eu, I, Li, Mo, Pr, Rb, Sb, Se, Ta, Te, Th, Tl, V, and W; (4) total U by kinetic phosphorescence analysis; (5) Ion chromatography for Cl, F, NO{sub 2}, NO{sub 3}, PO{sub 4}, SO{sub 4}, acetate, formate, oxalate, and citrate; (6) Density, inorganic carbon and organic carbon by two different methods, mercury, free hydroxide, ammonia, and cyanide. The 241-AP-101 composite met all

  3. Uptake from water and tissue distribution of neptunium-237 in crabs, shrimp and mussels

    The uptake of 237Np has been followed in the tissues of mussels, shrimp and crabs exposed to the actinide in sea-water under controlled conditions. Bioaccumulation was observed in all tissues examined with the highest concentration factors noted in the external shells of the three species. Despite some incorporation of 237Np into internal tissues, it is noteworthy that after prolonged exposure 92-98% of the organisms' total 237Np content was associated with the non-edible shells. The general behaviour of this toxic transuranic element in invertebrate tissues appears to be very similar to that of plutonium. (author)

  4. Nuclear Criticality Safety of the DOT 9975 Container for237NpO2Storage, Handling, and Transport

    Reed, D.A.

    2003-08-29

    Nuclear criticality safety considerations are presented to address use of the DOT 9975 shipping container for {sup 237}NpO{sub 2}. The DOT 9975 container will be used by multiple DOE sites and contractors. Various of site- and activity-specific NCS and facility safety documents are yet to be developed. For these reasons, an overall assessment of criticality safety of {sup 237}NpO{sub 2}-loaded DOT 9975 containers is considered useful to personnel involved in generating, reviewing, or approving these various documents. It is concluded that inherent container features, the loading per container (maximum of 6 kg {sup 237}Np), and the nuclear physics properties of {sup 237}NpO{sub 2} combine to preclude the potential for a nuclear criticality accident. This conclusion applies to storage, handling, and transport operations involving closed DOT 9975 packages, including credible off-normal conditions that may result in damage to packages during those operations.

  5. Investigation on migration behavior of TRU-nuclides

    The migration behavior of TRU nuclides in geological formation has been studied by a batch and a column method, considering the influence of humic complexation and colloid formation. The migration test of 237Np and 238Pu is carrying out in natural field, to verify the data and the conventional migration model for the safety evaluation of TRU waste disposal. It was found that the migration of 237Np and 238Pu in the natural field is largely retarded sorption onto soil. (author)

  6. Fission cross section calculations for Pa isotopes

    Based on the recently measured cross-section values for the neutron-induced fission of 231Pa and our experience gained with other isotopes, new self consistent neutron cross section calculations for n+231Pa have been performed up to 30 MeV. The results are quite different to the existing evaluations, especially above the first chance fission threshold. (authors)

  7. Preliminary Neutronics Analysis Of Fuel Pebble With Thorium Fuel Cycle

    A new fuel pebble was designed based on Thorium fuel cycle. 231Pa has been added into fuel pebble for obtaining the minimum reactivity swing. The results show that the new designed pebble fuel with 7.0 % 233U enrichment adding 3.2% 231Pa, the keff is to be controlled up to 65 GWd/t; the other design with 8.0 % 233U enrichment requires 3.9% 231Pa, the keff therefore is remain up to 80 GWd/t. About 95% of loaded 231Pa in fuel pebble is depleted after 120 GWd/t. The results imply that it is optimistic to design the fuel pebble with 233U, 231Pa and 232Th; but some effects such as fuel temperature effect, distribution of TRISO particle in pebble fuel, etc. are required to investigate. (author)

  8. Neptunium Transport Behavior in the Vicinity of Underground Nuclear Tests at the Nevada Test Site

    Zhao, P; Tinnacher, R M; Zavarin, M; Williams, R W; Kersting, A B

    2010-12-03

    We used short lived {sup 239}Np as a yield tracer and state of the art magnetic sector ICP-MS to measure ultra low levels of {sup 237}Np in a number of 'hot wells' at the Nevada National Security Site (NNSS), formerly known as the Nevada Test Site (NTS). The results indicate that {sup 237}Np concentrations at the Almendro, Cambric, Dalhart, Cheshire and Chancellor sites, are in the range of 3 x 10{sup -5} to 7 x 10{sup -2} pCi/L and well below the MCL for alpha emitting radionuclides (15 pCi/L) (EPA, 2009). Thus, while Np transport is believed to occur at the NNSS, activities are expected to be well below the regulatory limits for alpha-emitting radionuclides. We also compared {sup 237}Np concentration data to other radionuclides, including tritium, {sup 14}C, {sup 36}Cl, {sup 99}Tc, {sup 129}I, and plutonium, to evaluate the relative {sup 237}Np transport behavior. Based on isotope ratios relative to published unclassified Radiologic Source Terms (Bowen et al., 1999) and taking into consideration radionuclide distribution between melt glass, rubble and groundwater (IAEA, 1998), {sup 237}Np appears to be substantially less mobile than tritium and other non-sorbing radionuclides, as expected. However, this analysis also suggests that {sup 237}Np mobility is surprisingly similar to that of plutonium. The similar transport behavior of Np and Pu can be explained by one of two possibilities: (1) Np(IV) and Pu(IV) oxidation states dominate under mildly reducing NNSS groundwater conditions resulting in similar transport behavior or (2) apparent Np transport is the result of transport of its parent {sup 241}Pu and {sup 241}Am isotopes and subsequent decay to {sup 237}Np. Finally, measured {sup 237}Np concentrations were compared to recent Hydrologic Source Term (HST) models. The 237Np data collected from three wells in Frenchman Flat (RNM-1, RNM-2S, and UE-5n) are in good agreement with recent HST transport model predictions (Carle et al., 2005). The agreement

  9. Study on the radionuclide elution from quartz sand source and their speciation

    The study of the elution of the radionuclide from quartz sand source and their speciation is carried out by column method. The colloid form of nuclides in the eluted solution is studied by ultra-filtration method. The existing form of the nuclides on the sand after elution is studied with sequential extraction method. When the volume of eluted solution is up to 110 times of the column volume, the nuclide 237Np of more than 90% is eluted, and in the exchangeable form. The nuclide 237Np remained in the sand is mainly in the form of being coincident with the matrix of carbonate (5.5%) and the transition metals, iron and manganese (1.3%). The elution of 238Pu from sand is more difficult than that of 237Np. 238Pu may exist in colloid form in eluted solution

  10. Subcellular localization of neptunium-237 in lung and kidney after intratracheal administration in the rat: An ultrastructural and microanalytical study

    Chronic intratacheal administration of 237Np to rats was performed during 6 weeks. The total dose administered was 45.8 kBq. Two methods, electron microscopy and electron probe X-ray microanalysis, were used to determined the intracellular sites of localization of 237Np. Clusters of dense granules were observed in nuclei of pneumocytes and proximal tubular cells of the kidneys. These clusters have been shown to contain neptunium associated with phosphorus, sulfur and calcium. Alternations of nuclei and ultrastructural cytoplasmic lesions were observed. The absorbed doses in lungs and kidneys were very low. These results suggest that the chemical toxicity of 237Np is more important than its radiological toxicity. 30 refs., 2 figs

  11. Method for Determination of Neptunium in Large-Sized Urine Samples Using Manganese Dioxide Coprecipitation and 242Pu as Yield Tracer

    Qiao, Jixin; Hou, Xiaolin; Roos, Per

    2013-01-01

    A novel method for bioassay of large volumes of human urine samples using manganese dioxide coprecipitation for preconcentration was developed for rapid determination of 237Np. 242Pu was utilized as a nonisotopic tracer to monitor the chemical yield of 237Np. A sequential injection extraction...... 100% and high separation capacity of processing up to 5 L of human urine samples. The MnO2 coprecipitation process is simple and straightforward in which a batch (8–12) of samples can be pretreated within 4 h (i.e., <0.5 h/sample). In connection with the automated column separation and ICPMS...... quantification, which takes less than 1.5 h in total, the overall analytical time was on average less than 2 h for each sample. The high effectiveness and sample throughput make the developed method well suited for urine bioassay of 237Np in routine monitoring of occupationally internal radiation exposure and...

  12. Neptunium determination by inductively coupled plasma mass spectrometry (ICP-MS)

    The determination of neptunium-237 (237Np) traditionally has been performed by alpha spectrometry or neutron activation analysis. These methods are labor intensive and require several days for completion. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is a possible alternative for 237Np determinations. This paper describes the analytical method developed for samples that have significant levels of uranium present. The lower reporting limits achievable by ICP-MS are competitive with the counting methods, but the real advantage for this laboratory lies in the lower cost and faster turnaround time provided by ICP-MS. (author)

  13. Non-conventional measurement techniques for the determination of some long-lived radionuclides produced in nuclear fuel

    The results of a literature survey on non-radiometric analytical techniques for the determination of long-lived radionuclides are described. The methods which have been considered are accelerator mass spectrometry, inductively coupled plasma mass spectrometry, thermal ionization mass spectrometry, resonance ionization spectrometry, resonance ionization mass spectrometry and neutron activation analysis. Neutron activation analysis has been commonly used for the determination of 129I and 237Np in environmental samples. Inductively coupled mass spectrometry seems likely to become the method of choice for the determination of 99Tc, 237Np and Pu-isotopes. The methods are discussed and the chemical separation methods described. (orig.)

  14. Systematic study of anomalous fragment anisotropies in near- and sub-barrier fusion-fission reactions

    The fusion cross sections and fragment angular distributions for the complete fusion-fission reactions of 11B+238U, 237Np, 12C+237Np, 16O+232Th, 238U, and 19F+23Th at near- and sub-barrier energies have been measured by the fragment folding angle technique. It is revealed that the anomalous anisotropies of fission fragments in latter three systems are existence. Based on the experimental observations and Dressing and Randrup's theory, a new version model of preequilibrium fission is put forward to explain the anomaly. (author)

  15. Non-conventional measurement techniques for the determination of some long-lived radionuclides produced in nuclear fuel

    The results of a literature survey on non-radiometric analytical techniques for the determination of long-lived radionuclides are described. The methods which have been considered are accelerator mass spectrometry, inductively coupled plasma mass spectrometry, thermal ionization mass spectrometry, resonance ionization spectrometry, resonance ionization mass spectrometry and neutron neutron activation analysis. Neutron activation analysis has been commonly used for the determination of 129I and 237Np in environmental samples. Inductively coupled mass spectrometry seems likely to become the method of choice for the determination of 99Tc, 237Np and Pu-isotopes. The methods are discussed and the chemical separation methods described. (author) 88 refs.; 8 tabs

  16. Distribution of neptunium and plutonium in New Mexico lichen samples (Usnea arizonica) contaminated by atmospheric fallout

    The concentrations of 237Np, 239Pu and 240Pu were determined in lichen samples (Usnea arizonica) that were collected from ten locations in New Mexico between 2011 and 2013 using isotope dilution inductively-coupled plasma mass spectrometry (ID-ICP-MS). The observed isotopic ratios for 237Np/239Pu and 240Pu/239Pu indicate trace contamination from global and regional fallout (e.g. Trinity test and atmospheric testing at the Nevada Test Site). The fact that actinide contamination is detected in recent lichen collections suggests continuous re-suspension of fallout radionuclides even 50 years after ratification of the Limited Test Ban Treaty. (author)

  17. Neutron capture cross section measurement of Np-237 below 10 keV by linac time-of-flight method

    Lee, Samyol; Yamamoto, Shuji; Cho, Hyun-Je; Yoshimoto, Takaaki; Kobayashi, Katsuhei; Fujita, Yoshiaki [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Ohkawachi, Yasushi [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center

    2001-03-01

    The neutron capture cross section of {sup 237}Np has been measured in the energy region from 0.01 eV to 10 keV by using the neutron time-of-flight (TOF) method with a 46 MeV electron linear accelerator (linac) at the Research Reactor Institute, Kyoto University (KURRI). A pair of C{sub 6}D{sub 6} scintillation detectors, which was placed at a distance of 12.0 {+-} 0.02 m from the pulsed neutron source, was employed for the prompt capture gamma-ray measurement from the {sup 237}Np sample. The measured result has been normalized to the reference value of the {sup 237}Np(n,{gamma}){sup 238}Np reaction in ENDF/B-VI at 0.0253 eV. The existing experimental and the evaluated capture cross sections in ENDF/B-VI and JENDL-3.2 have been compared with the present measurement. For the neutron capture cross section of {sup 237}Np, the data by Weston et al. and the evaluated data are in good agreement with the present measurement. However, the data by Hoffman et al. are obviously lower in the relevant energy region. The data, which were measured before using a lead slowing-down spectrometer at KURRI, have been in good agreement with the data obtained by energy-broadening the present TOF measurement. (author)

  18. Ionic speciation of Np in frozen solutions

    Light actinides exhibit many oxidation states (II) that are stable in salts and are relatively stable in solution. Np IV to Np VII solutions were prepared and quickly frozen. We report the preliminary results of the 237Np Mossbauer study. These results are discussed and compared to those available for Np compounds in the crystalline state or Np ions in solution. 3 refs

  19. Hanford intercontractor support

    Distribution coefficients (Kd values) were determined on subsoils from Washington and South Carolina for 241Am, 237Np, and 99Tc as a function of equilibrium solution concentration of calcium (Ca2+) and of sodium (Na+). Kd values decreased in all cases with increasing solution concentrations of Ca2+ and Na+. For the South Carolina subsoil Kd values ranged from 1.0 to 67 for 241Am as a function of Ca2+, from 0.2 to 0.002 M, respectively, 1.6 to 280 for 241Am as a function of Na+, 0.43 to 0.66 for 237Np as a function of Ca2+, and 0.16 to 0.25 for 237Np as a function of Na+ from 3.0 less than 0.015 M, respectively. For the Washington soil, Kd values were greater than 1200 for 241Am and ranged from 0.36 to 2.37 as a function of Ca2+ and from 3.19 to 3.90 for 237Np as a function of Na+ over the above concentration ranges, respectively. Kd values for 99Tc were essentially 0 at all NaHCO3 concentrations on the South Carolina subsoil

  20. Preparation of tracer 239Np from 243Am

    The aim of this work is the preparation of tracer 239Np from 243Am by extraction chromatography as a separation method that can be used as a tracer to determine the radiochemical yield of 237Np in the analysis of environmental samples. (authors)

  1. Protected Plutonium Production by Transmutation of Minor Actinides for Peace and Sustainable Prosperity - Irradiation Tests of Np and Np-U Samples in Experimental Fast Reactor Joyo (JAEA) and Advanced Thermal Reactor ATR (INL)

    A project of Produce Protected Plutonium (P3) was proposed by Tokyo-Tech as a part of non-proliferation research for Plutonium (Pu) utilization to nuclear reactor. The project is to reach the production of inherently protected Pu by addition 237Np to Uranium (U) fuel. In order to validate this P3 concept, two irradiation tests were performed. Experimental determination of Pu isotopes in 237Np samples irradiated in the experimental fast reactor Joyo was done to evaluate 238Pu production from 237Np under the fast neutron spectra. The amount of 238Pu in the irradiated 237Np samples was determined by a radiochemical analysis in Alpha-gamma Facility of JAEA. The produced 238Pu in the samples was found to depend on the neutron spectrum, ranging from that of a typical fast reactor to a nearly epi-thermal spectrum. The fast reactor can potentially control the 238Pu production from 237Np by the spectrum shift in the different irradiation position. Within the framework of the P3, the fast reactor can make roles of protected Pu production which can be better performed in the reflector region, the ratio of 238Pu is achieved up to around 90% produced from 237Np. On the other hand, 2, 5 and 10% 237Np containing U samples were also irradiated in Advanced Thermal Reactor of INL to evaluate the 238Pu production under thermal neutron region. The irradiation condition and its loading position of samples were fixed based on a calculation with MCWO (MCNP Coupled with ORIGEN2) code. The fuel specimens were removed from the core at 100, 200 and 300 effective full power days (EFPD), and then post irradiation examination was completed at Chemical lab. in MFC of INL. For the samples after 300 EFPD irradiation, Np depletion were about 60 % for 2% Np-U samples, about 50% for 5 and 10 % Np-U samples. The 238Pu to Pu ratio was about 20%, 30% and 45% for 2%, 5%, and 10% Np-U samples, respectively. The neutronics calculation results were coincident with the experimental ones. Acknowledgments: The

  2. Impact of fission product partitioning and transmutation of Np-237, I-127 and Tc-99 on waste disposal strategies

    From the point of view of waste management, three isotopes 237Np, 129I and 99Tc deserve particular attention since they cannot be confined within any presently known geological barrier. The safety assessment studies showed that 129I diffuses through 50 m of clay after 5000 years and creates a radiological burden which is superior to the other nuclides. 99Tc and 237Np emerge much later (million years) but cannot be confined in the repository. Separation of 237Np is already envisaged by the reprocessing plants and small modifications to the PUREX process permit to separate this nuclide quantitatively. However, the overall Np reduction factor cannot be higher than 3 to 4 because 237Np is formed by alpha-decay of 241Am which is immobilized in the glass. The irradiation technology to transmute 237Np into 238Pu is available. Iodine is separated from the dissolver off-gases in the reference fuel cycle and could be transformed into a stable Ba(IO3)2 matrix which can serve as irradiation 1291 matrix to destroy. Technetium is produced as insoluble residue and occurs in the waste streams together with Ru, Rh and Pd. Its recovery is still questionable and needs further developments. Irradiation of small targets in HFRs can lead to a 90% transmutation of these long-lived isotopes but the irradiation periods (particularly for 129I) are very long. The present HFR generation is not designed to handle large amounts of long-lived radionuclides and new more powerful units ought to be designed for that purpose. (author)

  3. Impact of fission product partitioning and transmutation of Np-237, I-127 and Tc-99 on waste disposal strategies

    Beatsle, L.H. [Studiecentrum voor Kernenergie - Centre d' Etude de l' Energie Nucleaire (SCK-CEN), Mol (Belgium)

    1991-07-01

    From the point of view of waste management, three isotopes {sup 237}Np, {sup 129}I and {sup 99}Tc deserve particular attention since they cannot be confined within any presently known geological barrier. The safety assessment studies showed that {sup 129}I diffuses through 50 m of clay after 5000 years and creates a radiological burden which is superior to the other nuclides. {sup 99}Tc and {sup 237}Np emerge much later (million years) but cannot be confined in the repository. Separation of {sup 237}Np is already envisaged by the reprocessing plants and small modifications to the PUREX process permit to separate this nuclide quantitatively. However, the overall Np reduction factor cannot be higher than 3 to 4 because {sup 237}Np is formed by alpha-decay of {sup 241}Am which is immobilized in the glass. The irradiation technology to transmute {sup 237}Np into {sup 238}Pu is available. Iodine is separated from the dissolver off-gases in the reference fuel cycle and could be transformed into a stable Ba(IO{sub 3}){sub 2} matrix which can serve as irradiation 1291 matrix to destroy. Technetium is produced as insoluble residue and occurs in the waste streams together with Ru, Rh and Pd. Its recovery is still questionable and needs further developments. Irradiation of small targets in HFRs can lead to a 90% transmutation of these long-lived isotopes but the irradiation periods (particularly for {sup 129}I) are very long. The present HFR generation is not designed to handle large amounts of long-lived radionuclides and new more powerful units ought to be designed for that purpose. (author)

  4. ZZ MATXSLIBJ33, JENDL-3.3 based, 175 N-42 photon groups (VITAMIN-J) MATXS library for discrete ordinates multi-group

    -156, Gd-152, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, Tb-159, Er-162, Er-164, Er-166, Er-167, Er-168, Er-170, Hf-174, Hf-176, Hf-177, Hf-178, Hf-179, Hf-180, Ta-181, W-182, W-183, W-184, W-186, Hg-196, Hg-198, Hg-199, Hg-200, Hg-201, Hg-202, Hg-204, Pb-204, Pb-206, Pb-207, Pb-208, Bi-209, Ra-223, Ra-224, Ra-225, Ra-226, Ac-225, Ac-226, Ac-227, Th-227, Th-228, Th-229, Th-230, Th-232, Th-233, Th-234, Pa-231, Pa-232, Pa-233, U-232, U-233, U-234, U-235, U-236, U-237, U-238, Np-235, Np-236, Np-237, Np-238, Np-239, Pu-236, Pu-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Pu-244, Pu-246, Am-241, Am-242, Am-242m, Am-243, Am-244, Am-244m, Cm-240, Cm-241, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246, Cm-247, Cm-248, Cm-249, Cm-250, Bk-247, Bk-249, Bk-250, Cf-249, Cf-250, Cf-251, Cf-252, Cf-254, Es-254, Es-255, Fm-255 Temperatures: 300 K. Origin: JENDL-3.3. Weighting spectrum: -- iwt=11 for NJOY-99. Legendre expansion: P6. Thermal scattering: free gas model. Self shielding: sigma-0, infinity, 10000, 1000, 300, 100, 30, 10, 1, 0.1, 1. E-5. Kerma factors are provided. NEA-1707/03: Corrections were made to the continuous inelastic scattering matrices (MT=91), for all nuclides for which this channel is open. This replaces the previous version. 2 - Methods: The nuclear data processing system NJOY-99.67 was used to produce MATXSLIBJ33. It can be further processed using TRANSX-2.15. 3 - Restrictions on the complexity of the problem: Accuracy of pointwise cross-section reconstruction: 0.1%; Upper limit of thermal region: 4.6 eV

  5. ZZ KASHIL-E70, 199 N, 42 Photon Groups Cross Sections in MATXS Format Based on ENDF/B-VII.0 for Shielding Applications

    1 - Description: Format: MATXS, 204 nuclides processed with NJOY99.245. Number of groups: 199 neutron-, 42 photon-groups. 204 Nuclides including 8 thermal scattering law data: H-1, H-2, H-3, He-3, He-4, Li-6, Li-7, Be-9, Be-9, Be-9, B-10, B-11, C-nat, C-nat, N-14, N-15, O-16, O-17, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, S-32, S-33, S-34, S-36, Cl-35, Cl-37, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Sc-45, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Y-89, Zr-90, Zr-91, Zr-92, Zr-94, Zr-96, Nb-93, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-100, Pd-102, Pd-104, Pd-105, Pd-106, Pd-108, Pd-110, Ag-107, Ag-109, Cd-106, Cd-108, Cd-110, Cd-112, Cd-113, Cd-114, Cd-116, In-113, In-115, I-127, Xe-124, Xe-126, Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, Xe-134, Xe-136, Cs-133, Ba-138, Pr-141, Nd-143, Nd-145, Nd-146, Nd-148, Nd-150, Pm-147, Sm-147, Sm-151, Sm-152, Eu-151, Eu-152, Eu-153, Eu-154, Eu-155, Gd-152, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, Dy-164, Ho-165, Lu-175, Lu-176, Hf-174, Hf-176, Hf-177, Hf-178, Hf-179, Hf-180, Ta-181, Ta-182, W-182, W-183, W-184, W-186, Re-185, Re-187, Ir-191, Ir-193, Au-197, Pb-206, Pb-207, Pb-208, Bi-209, Th-230, Th-232, Pa-231, Pa-233, U-232, U-233, U-234, U-235, U-236, U-237, U-238, Np-237, Np-238, Np-239, Pu-236, Pu-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Pu-243, Pu-244, Am-241, Am-242, Am-242m, Am-243, Cm-241, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246, Cm-247, Cm-248, Bk-249, Cf-249, Cf-250, Cf-251, Cf-252, Cf-253, Es-253. Origin: ENDF/B-VII.0. Weighting spectrum: 300, 600, 1000, 2100 K. The KASHIL-E70 is a MATXS-format, 199-group neutron and 42-group photon cross section library for shielding applications based on ENDF/B-VII.0. The library contains 204 nuclide data including 8 thermal scattering law data processed by the NJOY99.259 code patched with NEA

  6. ZZ MCB-JEF2.2, MCB Continuous-Energy Neutron Cross Section Libraries for Temperatures from 300 to 1800 K

    -154, Eu-155, Eu-156, Eu-157, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, Tb-159, Tb-160, Dy-160, Dy-161, Dy-162, Dy-163, Dy-164, Ho-165, Er-166, Er-167, Lu-175, Lu-176, Hf-174, Hf-176, Hf-177, Hf-178, Hf-179, Hf-180, Ta-181, Ta-182, W-182, W-183, W-184, W-186, Re-185, Re-187, Au-197, Pb-nat., Bi-209, Th-230, Th-232, Pa-231, Pa-233, U-232, U-233, U-234, U-235, U-236, U-237, U-238, Np-237, Np-238, Np-239, Pu-236, Pu-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Pu-243, Pu-244, Am-241, Am-242, Am-242m, Am-243, Cm-241, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246, Cm-247, Cm-248, Bk-249, Cf-249, Cf-250, Cf-251, Cf-252, Cf-253, Es-253. Temperatures: 300 K, 600 K, 900 K, 1200 K, 1500 K, and 1800 K. Origin: JEF-2.2. 2 - Methods: The library was generated using the NJOY processing code. An example of the input data is provided

  7. Optimization of small long-life PWR based on thorium fuel

    A conceptual design of small long-life Pressurized Water Reactor (PWR) using thorium fuel has been investigated in neutronic aspect. The cell-burn up calculations were performed by PIJ SRAC code using nuclear data library based on JENDL 3.2, while the multi-energy-group diffusion calculations were optimized in three-dimension X-Y-Z geometry of core by COREBN. The excess reactivity of thorium nitride with ZIRLO cladding is considered during 5 years of burnup without refueling. Optimization of 350 MWe long life PWR based on 5% 233U & 2.8% 231Pa, 6% 233U & 2.8% 231Pa and 7% 233U & 6% 231Pa give low excess reactivity

  8. Optimization of small long-life PWR based on thorium fuel

    Subkhi, Moh Nurul; Suud, Zaki; Waris, Abdul; Permana, Sidik

    2015-09-01

    A conceptual design of small long-life Pressurized Water Reactor (PWR) using thorium fuel has been investigated in neutronic aspect. The cell-burn up calculations were performed by PIJ SRAC code using nuclear data library based on JENDL 3.2, while the multi-energy-group diffusion calculations were optimized in three-dimension X-Y-Z geometry of core by COREBN. The excess reactivity of thorium nitride with ZIRLO cladding is considered during 5 years of burnup without refueling. Optimization of 350 MWe long life PWR based on 5% 233U & 2.8% 231Pa, 6% 233U & 2.8% 231Pa and 7% 233U & 6% 231Pa give low excess reactivity.

  9. Optimization of small long-life PWR based on thorium fuel

    Subkhi, Moh Nurul, E-mail: nsubkhi@students.itb.ac.id [Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Science, Bandung Institute of Technology. Jalan Ganesha 10, Bandung (Indonesia); Physics Dept., Faculty of Science and Technology, State Islamic University of Sunan Gunung Djati Bandung Jalan A.H Nasution 105 Bandung (Indonesia); Suud, Zaki, E-mail: szaki@fi.itb.ac.id; Waris, Abdul; Permana, Sidik [Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Science, Bandung Institute of Technology. Jalan Ganesha 10, Bandung (Indonesia)

    2015-09-30

    A conceptual design of small long-life Pressurized Water Reactor (PWR) using thorium fuel has been investigated in neutronic aspect. The cell-burn up calculations were performed by PIJ SRAC code using nuclear data library based on JENDL 3.2, while the multi-energy-group diffusion calculations were optimized in three-dimension X-Y-Z geometry of core by COREBN. The excess reactivity of thorium nitride with ZIRLO cladding is considered during 5 years of burnup without refueling. Optimization of 350 MWe long life PWR based on 5% {sup 233}U & 2.8% {sup 231}Pa, 6% {sup 233}U & 2.8% {sup 231}Pa and 7% {sup 233}U & 6% {sup 231}Pa give low excess reactivity.

  10. Protactinium and isotopes of thorium in metalliferous sediments from the Bauer depression

    Results are presented of a study of the vertical distribution of 238U, 234U, 232Th, 230Th, and 231Pa isotopes in a column of metalliferous sediments from the Bauer depression (southeastern part of the Pacific Ocean). On the basis of the obtained data a hypothesis is formulated concerning the authigenic production of 230Th and 231Pa in these deposits, i.e, the similarity of the physicochemical behavior of 230Th and 231Pa found in pelagic sediments is found in these specific sediments also. We present arguments in favor of the identical behavior of these radionuclides in the marine environment. With the help of the ionium method of dating marine sediments, the average rate of sedimentation of the investigated column of metalliferous sediments from the Bauer depression was calculated

  11. Protactinium and thorium isotopes in metal-containing precipitates from Bauer depression

    The results studying vertical distribution of 238U, 234U, 232Th, 230Th and 231Pa isotopes in the colomn of metalliferous sediments from Bauer depression (South-East part of the Pacific ocean) are presented. On the basis of the data obtained the supposition about the authigenic origin of 230Th and 231Pa in these ocean sedimentations, is stated, i.e. even in such specific ocean sediments closeness of physical chemical behaviour of 230Th and 231Pa is fixed. Arguments for identical behaviour of these radionuclides in sea water are presented. Average rate of sedimentation of the column investigated of metalliferous sediments from Bauer depression is calculated using the ionic method of ocean deposition dating

  12. The Geochemical Behavior of Tc, Np, and Pu in Spent Nuclear Fuel in an Oxidizing Environment

    Studies at the Nopal and Shinkolowbwe uranium deposits show that the primary uraninite (UO2) altered to a suite of secondary uranyl minerals similar to those observed in corrosion tests with uranium oxide . Although the Nopal I deposit tells us something about the possible fate of uranium, it tells us little about the likely fate of the important long-lived radionuclides; iodine (129I), cesium (135Cs), technetium (99Tc), neptunium (237Np), and plutonium (239Pu). Most performance assessment (PA) models, assume conservatively, that as the UO2 matrix corrodes, the key radionuclides (129I, 99Tc, 237Np, and 239Pu) will be released congruently. In so doing, these PA models force increased reliance on human engineered barriers

  13. The Geochemical Behaviour of Tc, Np, and Pu in Spent Nuclear Fuel in an Oxidizing Environment

    Buck, Edgar C.; Hanson, Brady D.; McNamara, Bruce K.; R. Giere and P. Stille

    2004-10-01

    Studies at the Nopal and Shinkolowbwe uranium deposits show that the primary uraninite (UO2) altered to a suite of secondary uranyl minerals similar to those observed in corrosion tests with uranium oxide . Although the Nopal I deposit tells us something about the possible fate of uranium, it tells us little about the likely fate of the important long-lived radionuclides; iodine (129I), cesium (135Cs), technetium (99Tc), neptunium (237Np), and plutonium (239Pu). Most performance assessment (PA) models, assume conservatively, that as the UO2 matrix corrodes, the key radionuclides (129I, 99Tc, 237Np, and 239Pu) will be released congruently. In so doing, these PA models force increased reliance on human engineered barriers.

  14. Standardization of 241Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting

    Balpardo, C; Rodrigues, D; Arenillas, P

    2010-01-01

    The nuclide 241Am decays by alpha emission to 237Np. Most of the decays (84.6 %) populate the excited level of 237Np with energy of 59.54 keV. Digital Coincidence Counting was applied to standardize a solution of 241Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid Scintillation Counting using the logical sum of double coincidences in a TDCR array and Defined Solid Angle Counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

  15. Neptunium distribution in PUREX process streams

    237Np is one of the most important minor actinides present in spent fuel both from environmental and application point of view. The routing of neptunium to the particular waste stream of PUREX process is required for its separation and purification as 237Np is the target nuclide for production of 238Pu. In addition, the routing of neptunium to a particular PUREX stream will help in better waste management, which in turn will reduce its bearing on the environment considering its long half life, alpha emitting properties and mobile nature. In order to route Neptunium to a particular waste stream of PUREX process, it is imperative to understand the distribution of neptunium in various process streams. Although, there are reports on Np distribution under simulated conditions of PUREX streams, the present study deals with neptunium determination in actual PUREX streams samples. (author)

  16. Application of off/on line sequential injection system with high resolution ICP-MS to measurement radionuclides in environmental samples

    Chang-Kyu Kim (IAEA, Physics, Chemistry and Instrumentation Lab., Agency' s Laboratories, Seibersdorf (Austria))

    2010-03-15

    A sequential injection system was developed, which can be widely used for the separation and preconcentration of analytes from diverse environmental samples. The system enables the separation time to be shortened by maintaining a constant flow rate of solution and by avoiding clogging or bubbling in a chromatographic column. The SI system was successfully applied to the separation of 237Np and Pu isotopes in IAEA reference materials and environmental samples, and to the sequential separation of 210Po and 210Pb in a phosphogypsum candidate reference material. The replicate analysis results of 237Np, 239+240Pu 210Po and 210Pb in some IAEA reference materials using the SI system associated with HR-ICP-MS, alpha-spectrometry and LSC are in good agreement with the recommended value within 5% of standard deviation. The SI system enabled a halving of the separation time required for radionuclides. (author)

  17. A chromatographic separation of neptunium and protactinium using 1-octanol impregnated onto a solid phase support

    We have developed a new chromatographic method to efficiently separate and isolate neptunium (Np) and protactinium (Pa), based on the selective extraction of protactinium by primary alcohols. The effectiveness of the new technology is demonstrated by efficient separation of 233Pa from parent radionuclide 237Np, using a hydrochloric acid mobile-phase medium. Our new approach reproducibly isolated 233Pa tracer with a yield of 99 ± 1 % (n = 3; radiochemical purity 100 %) and enabled chemical recovery of 237Np parent material of 92 ± 3 % (radiochemical [99 %) for future 233Pa tracer preparations. Compared to previous methods, the new approach reduces radioactive inorganic and organic waste; simplifies the separation process by eliminating cumbersome liquid-liquid extractions; and allows isolation of radiochemically-pure fractions in less than 1 h. (author)

  18. Angular distributions in the neutron-induced fission of actinides

    In 2003 the n_TOF Collaboration performed the fission cross section measurement of several actinides ($^{232}$Th, $^{233}$U, $^{234}$U, $^{237}$Np) at the n_TOF facility using an experImental setup made of Parallel Plate Avalanche Counters (PPAC). The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. We have been therefore able to cover the very broad neutron energy range 1eV-1GeV, taking full benefit of the unique characteristics of the n_TOF facility. Figure 1 shows an example obtained in the case of $^{237}$Np where the n_ TOF measurement showed that the cross section was underestimated by a large factor in the resonance region.

  19. Refinement of Pu parent-daughter isotopic and concentration analysis for forensic (dating) purposes

    Plutonium (Pu) metal samples from an interlaboratory exchange exercise and simulated swipe samples were dated using plutonium-uranium (Pu-U) and plutonium-americium (Pu-Am). Metal data were evaluated for consistency and the swipe data against its source material. Metal ages based on 239Pu versus 235U and 240Pu versus 236U agreed to within a few percent, while the 238Pu-234U and 241Pu-241Am measurements had larger uncertainties. Swipe ages compared favorably with the material's known history. Neptunium (237Np) analyses were examined in the context of the 241Pu-241Am-237Np system to estimate whether Np can provide insights on material from which Am, Np, and U were removed. (author)

  20. Solid state track recorder measurements in the poolside critical assembly

    Fission rate measurements using solid state track recorders (SSTR) have been performed at the PCA. A schematic representation of a cross-section of the PCA is shown. Fission rates were measured in the pressure vessel simulator at the T/4, T/2 and 3T/4 positions and in the void box (VB). SSTR measurements were carried out with 232Th, 235U (bare and cadmium covered), 238U and 237Np fissionable deposits. Midplane only measurements were carried out for 235U and 237Np, while 5 axial locations at 1/4T and 1/2T and 3 axial locations at 3/4T and in the VB were sampled for 232Th and 238U. The HEDL SSTR fission rate measurements reported herein for both configurations together with NBS and CEN/SCK fission chamber measurements will be used to establish absolute and relative fission reaction rates, and ratios for the PCA pressure vessel Benchmark Facility

  1. FFTF (FAST FLUX TEST FACILITY) REACTOR CHARACTERIZATION PROGRAM ABSOLUTE FISSION RATE MEASUREMENTS

    FULLER JL; GILLIAM DM; GRUNDL JA; RAWLINS JA; DAUGHTRY JW

    1981-05-01

    Absolute fission rate measurements using modified National Bureau of Standards fission chambers were performed in the Fast Flux Test Facility at two core locations for isotopic deposits of {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu. Monitor chamber results at a third location were analyzed to support other experiments involving passive dosimeter fission rate determinations.

  2. FFTF (Fast Flux Test Facility) Reactor Characterization Program: Absolute Fission-rate Measurements

    Fuller, J.L.; Gilliam, D.M.; Grundl, J.A.; Rawlins, J.A.; Daughtry, J.W.

    1981-05-01

    Absolute fission rate measurements using modified National Bureau of Standards fission chambers were performed in the Fast Flux Test Facility at two core locations for isotopic deposits of {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np, {sup 239}Pu, {sup 240}Pu, and {sup 241}Pu. Monitor chamber results at a third location were analyzed to support other experiments involving passive dosimeter fission rate determinations.

  3. Translation of selected papers published in Nuclear Constants, No. 3(57), Moscow 1984

    The document contains the English translation of 6 papers selected for the nuclear data interest, (mainly the determination and the evaluation of the fast fission cross sections of 232Th, 235U, 238U, 237Np, 243Am) which were published in ''Topics in Atomic Science and Technology'', Series Nuclear Constants, No. 3(57), Moscow (1984). The original report was distributed as INDC(CCP)-240/G. Refs, figs and tabs

  4. Selected articles translated from Jadernye Konstanty (Nuclear Constants) volumes 1-2, 1995

    This report contains selected articles translated from Russian language which are dealing with nuclear constants. The MENDL-2 cross section library, universal library of fission products, evaluation of fission cross section for 237Np, evaluation of the photoneutron reaction cross sections, analysis of reaction rate measurements for determination of neutron energy spectra are specially dealt with. It contains five articles and each one is separately indexed. Refs, figs, tabs

  5. Analysis of the evaluated data discrepancies for minor actinides and development of improved evaluation

    Ignatyuk, A. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-03-01

    The work is directed on a compilation of experimental and evaluated data available for neutron induced reaction cross sections on {sup 237}Np, {sup 241}Am, {sup 242m}Am and {sup 243}Am isotopes, on the analysis of the old data and renormalizations connected with changes of standards and on the comparison of experimental data with theoretical calculation. Main results of the analysis performed by now are presented in this report. (J.P.N.)

  6. Average resonance parameters evaluation for actinides

    Porodzinskij, Yu.V.; Sukhovitskij, E.Sh. [Radiation Physics and Chemistry Problems Inst., Minsk-Sosny (Belarus)

    1997-03-01

    New evaluated <{Gamma}{sub n}{sup 0}> and values for {sup 238}U, {sup 237}Np, {sup 243}Cm, {sup 245}Cm, {sup 246}Cm and {sup 241}Am nuclei in the resolved resonance region are presented. The applied method based on the idea that experimental resonance missing results in correlated changes of reduced neutron widths and level spacings distributions is discussed. (author)

  7. Actinides separation and long-lived fission products from the high activity effluent

    The aim of this document is to study the decontamination of a high activity effluent in minor actinides-α transmitters (241Am, 243Am, 243Cm, 245Cm, 237Np, 238Pu, 242Pu, 235U, 238U) and long-life fissions products (133Cs, 137Cs) and then the separation of Am, Cm, Np, Cs and Pu, U traces. (TEC). 16 figs., 1 tab

  8. Calculation of fission fragment angular anisotropy in heavy-ion induced fission

    Fission fragment angular anisotropies from 16O + 232Th, 12C + 236U, 11B + 237Np, 14N + 232Th, 11B + 235U and 12C + 232Th systems were calculated by means of the standard saddle point statistical model (SSPSM). The results were obtained with and without neutron emission correction in the reactions, and comparisons were made with the corresponding experimental data. The normal and anomalous behaviors of fission fragment anisotropies are extensively discussed. (author)

  9. Measurements of Fission Cross Sections of Actinides

    Wiescher, M; Cox, J; Dahlfors, M

    2002-01-01

    A measurement of the neutron induced fission cross sections of $^{237}$Np, $^{241},{243}$Am and of $^{245}$Cm is proposed for the n_TOF neutron beam. Two sets of fission detectors will be used: one based on PPAC counters and another based on a fast ionization chamber (FIC). A total of 5x10$^{18}$ protons are requested for the entire fission measurement campaign.

  10. Isoscaling and fission modes in the yields of the Kr and Xe isotopes from photofission of actinides

    Drnoyan, J.; Zhemenik, V. I.; Mishinsky, G. V.

    2016-05-01

    Yields of Kr and Xe isotopes in photofission of 232Th, 238U, 237Np, 244Pu, 243Am, and 248Cm were tested for isoscaling dependence. Isoscaling for Kr is revealed. For Xe, isoscaling is found to be affected by the STI and STII fission modes governed by the N = 82 and N = 88 neutron shells. The work was performed at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (JINR).

  11. Modelling of reaction cross sections and prompt neutron emission

    Oberstedt S.; Tudora A.; Hambsch F.-J.

    2010-01-01

    Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra) as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f) and 237Np(n, f)) both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  12. Optimization of solvent extraction cycles to separate plutonium and neptunium

    This paper describes the steps taken to assess the potential of a solvent extraction process for separating plutonium from neptunium. The plutonium, namely 238Pu, is of importance because it is the isotope used in making radioisotope thermoelectric generators and radioisotope heaters and is obtained by irradiating 237Np targets in a high neutron flux environment. After the neptunium targets have been irradiated, the targets could then be processed by solvent extraction methods

  13. The fission fragment yields at the photofission of actinide nuclei

    The fission fragment yields of isotopes 101Mo, 135I, 135mCs were measured at the photo-fission of actinide nuclei 232Th, 238U, 237Np. These fission fragments have some peculiarities in nuclear structure or in practical using. The measurements were performed on the microtron bremsstrahlung at the Flerov Laboratory of Nuclear Reactions, JINR, at the electron energy 22 MeV. The activation method with an HPGe detector was used in these measurements of the yields

  14. Nordic collaboration on the use of mass-spectrometers for the analysis of radioisotopes. NKS-project NORCMASS. Final report

    This report cover an overview of the work performed during a three year (2003-2005) project initialized with the purpose of identifying and work on problems in isotope ratio and ultra trace measurements of primarily plutonium and uranium isotopes and 237Np using ICPMS. The project also included an educational part aiming to describe fundamental aspects and practical steps for radioisotope measurements using ICP-MS. (au)

  15. Electron paramagnetic resonance and electron nuclear double resonance of 237-neptunium hexafluoride in uranium hexafluoride single crystals

    Butler, James E.; Hutchison, Clyde A., Jr.

    1981-03-01

    The EPR and ENDOR spectra of 237NpF6 molecules dilutely substituted for host molecules in single crystals of UF6 at temperatures between 1.2 and 2.1 °K have been obtained at microwave frequencies, ˜9.4 and ˜9.7 GHz. Approximate values are given for the parameters in a spin Hamiltonian formalism that describes the measurements. The results are discussed.

  16. Reanalysis of the Gas-cooled fast reactor experiments at the zero power facility Proteus - Spectral indices

    Perret, G.; Pattupara, R. M.; Girardin, G.; Chawla, R.

    2013-03-01

    PROTEUS is a zero power reactor at the Paul Scherrer Institute which has been employed during the 1970's to study experimentally the physics of the gas-cooled fast reactor. Reaction rate distributions, flux spectrum and reactivity effects have been measured in several configurations featuring PuO2/UO2 fuel, absorbers, large iron shields, and thorium oxide and thorium metal fuel either distributed quasihomogeneously in the reference PuO2/UO2 lattice or introduced in the form of radial and axial blanket zones. This papers focus on the spectral indices - including fission and capture in 232Th and 237Np - measured in the reference PuO2/UO2 lattices and their predictions with an MCNPX model specially developed for the PROTEUS-GCFR core. Predictions were obtained with JEFF-3.1 and -3.11, ENDF/B-VII.0 and VII.1, and JENDL-3.3 and -4.0. A general good agreement was demonstrated. The ratio of 232Th fission to 239Pu fission, however, was under-predicted by 8.7±2.1% and 6.5±2.1% using ENDF/B-VII.0 and VII.1, respectively. Finally, the capture rates in 237Np tended to be underpredicted by the JEFF and JENDL libraries, although the new cross section in JEFF-3.1.1 slightly improved the 237Np capture to 239Pu fission results (3.4±2.4%).

  17. High-sensitivity fast neutron detector KNK-2-7M

    The construction of the fast neutron detector KNK-2-7M is briefly described. The results of the study of the detector in the pulse-counting mode are given for the fissions of 237Np nuclei in the radiator of the neutron-sensitive section and in the current mode with the separation of sectional currents of functional sections. The possibilities of determining the effective number of 237Np nuclei in the radiator of the neutronsensitive section are considered. The diagnostic possibilities of the detector in the counting mode are shown by example of the analysis of the reference data from the neutron-field characteristics in the working hall of the BR-K1 reactor. The diagnostic possibilities of the detector in the current operating mode are shown by example of the results of measuring the 237Np-fission intensity in the BR-K1 reactor power start-ups implemented in the mode of fission-pulse generation on delayed neutrons at the detector arrangement inside the reactor core cavity under conditions of a wide variation of the reactor radiation field

  18. Investigation of the nuclear data on the neutron beam of the IBR-30 and IBR-2 reactors

    Methodical aspects and results of the measurements, conducted on reactors IBR-30 and IBR-2 are presented. Measurements of the multiplicity spectra of gamma-quanta from the neutron capture reaction on the isotopes 48Ti, 113,115In, 117Sn, 127J, 149Sm, 165Ho, 175Lu, 177Hf, 178Hf, 185Re, 187Re, and 232Th have been done. These spectra were used for determination of the capture cross-section and according resonance parameters in the fission of 235U, 239Pu. The measurements were performed of resonance spins of isotopes 113,115In, 117Sn, 185,187Re, and 235U by the low-lying level population method in the thermal neutron energy area. The transmission and self-indication functions of filter samples 232Th, 237Np, and 238U were measured with different temperatures for determination the neutron cross-sections in the neutron energy range from 1 eV to 100 keV. The fission cross-section measurements of the minor actinides 234U, 237Np, and 243Am by the neutrons with energy below the fission barrier were carried out. The measurements of total yields and decay curve of the delayed neutrons from fission of 233,235U, 237Np by thermal and cold neutrons were performed

  19. The (3He, tf) as a surrogate reaction to determine (n, f) cross sections in the 10-20 MeV energy range

    The surrogate reaction 238U(3He, tf) is used to determine the 237Np(n, f) cross section indirectly over an equivalent neutron energy range from 10 to 20 MeV. A self-supporting ∼761 μg/cm2 metallic 238U foil was bombarded with a 42 MeV 3He2+ beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Outgoing charged particles and fission fragments were identified using the Silicon Telescope Array for Reaction Studies (STARS) consisted of two 140 μm and one 1000 μm Micron S2 type silicon detectors. The 237Np(n, f) cross sections, determined indirectly, were compared with the 237Np(n, f) cross section data from direct measurements, the Evaluated Nuclear Data File (ENDF/B-VII.0), and the Japanese Evaluated Nuclear Data Library (JENDL 3.3) and found to closely follow those datasets. Use of the (3He, tf) reaction as a surrogate to extract (n, f) cross sections in the 10-20 MeV equivalent neutron energy range is found to be suitable.

  20. Radiochemical determination of Np-237 in soil samples contaminated with weapon grade plutonium

    The Palomares terrestrial ecosystem (Andalusia, southwestern Spain) is known to constitute a natural laboratory to study the distribution, behaviour and migration of certain actinides, such as plutonium, americium and neptunium. This scenario is partially contaminated with weapon grade plutonium since the burn-out and fragmentation of two of the four thermonuclear bombs accidentally dropped by a B-52 from the USA Air Force back in 1966. While performing radiometric measurements on the field, with the goal of gathering information about the surface contamination levels, the possible presence of 237Np was observed through its 29 keV gamma emission. To accomplish a more detailed characterization of the source term in the contaminated area using the isotopic ratios Pu-Am-Np, the radiochemical isolation and later quantification by alpha spectrometry of 237Np was initiated. As a first approach, a bibliographic study was undertaken, considering different radiochemical methods applied to a variety of samples such as soils, sediments, sea water, lichens, etc. The radiochemical procedure selected in our laboratory involves separation of neptunium from americium, uranium and plutonium with ionic resin (AG 1x2), 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 resin. After electro-deposition, quantification is performed by high resolution alpha spectrometry. Different analyses have been performed with blank solutions spiked with 236Pu, 237Np and 244Cm, solutions resulting from the total dissolution of isolated radioactive particles and soil samples. The lack of an appropriate tracer in our lab led to the determination of an average percentage of Np recovery using a certified solution of 237Np. Decontamination percentages obtained during the Pu-Np separation ranged from 98 % to 100 %. Some tests to investigate the effect of the addition or absence of NaNO2 (responsible for

  1. The Tautavel cave and dating methods

    Main age estimation methods are described, datable materials and limits of application are given in each case. Methods studied are: carbon 14, 230Th/234U, 231Pa/235U, potassium-argon, thermoluminescence, electron spin resonance, fission tracks. Indirect methods like paleomagnetism and paleoclimates are briefly described

  2. Toxicty of thorium cycle nuclides

    The purpose of this project is to investigate the biological hazards associated with uranium-thorium breeder fuels and fuel recycle process solutions. Initial studies emphasize the metabolism and long-term biological effects of inhaled 233U-232U nitrate and oxide fuel materials andof 231Pa, a major, long-lived, radioactive waste product

  3. Study of extraction chromatography methods of separation of neptunium and its radiometric determination

    In presented dissertation thesis the separation procedure for determination of neptunium in model solutions and also in soil samples was designed. 1. The sorbent was prepared on basis of hydrophobised silica gel with silica oil for hydrophobisation - Lukooil H. Extraction agent was anchored on this modified surface -quarternary ammonium salt Aliquat 336. In experiments was proved, that sorbent prepared like this is resist enough to the elution solutions using in separation procedures. It was found out that maximal concentration of deposited Aliquat 336 in benzene on hydrophobised silica gel selected granulate size is 40%. Sorbent prepared with silica gel lower granulate size and also with higher concentration of Aliquat 336 in benzene became sticky and unsuitable for using in separation columns. 2. The prepared sorbent is similar to commercial produced TEVA resin made by company Eichrom and for purpose of this project it was cheaper but the same effective alternative in comparing to mentioned commercial resin. 3. The separation procedure for isolation of 237Np from radionuclides interfering during its radiometric determination with alpha spectrometry was designed -in scientific publications hasn't been described yet. The procedure consists of using formic acid for reduction of radionuclides interfering by alpha spectrometric determination of 237Np and subsequent purification of neptunium on the next column by using ferrous sulphamate as reduction agent. This procedure was applied to the model solutions and also to the soil samples. The model solutions and soil samples for these experiments were contaminated with known amounts of 237Np, 238pU, 232Th and mixture of 234U/238U. The effective separation of neptunium from described radionuclides was achieved with application of the described separation procedure. 4. The separation procedure for separation of 239Np from its mother radionuclide 241Am was designed with prepared sorbent. Different washing and elution

  4. Fission fragment angular distributions and fission cross section validation

    The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238U and 232Th have been investigated up to 100 MeV in a single experiment. The n-TOF Collaboration performed the fission cross section measurement of several actinides (232Th, 235U, 238U, 234U, 237Np) at the n-TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3. chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n-TOF facility at CERN. When compared to previous measurements, the n-TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n-TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np. This sphere was

  5. Partial neutron capture cross sections of actinides using cold neutron prompt gamma activation analysis

    Nuclear waste needs to be characterized for its safe handling and storage. In particular long-lived actinides render the waste characterization challenging. The results described in this thesis demonstrate that Prompt Gamma Neutron Activation Analysis (PGAA) with cold neutrons is a reliable tool for the non-destructive analysis of actinides. Nuclear data required for an accurate identification and quantification of actinides was acquired. Therefore, a sample design suitable for accurate and precise measurements of prompt γ-ray energies and partial cross sections of long-lived actinides at existing PGAA facilities was presented. Using the developed sample design the fundamental prompt γ-ray data on 237Np, 241Am and 242Pu were measured. The data were validated by repetitive analysis of different samples at two individual irradiation and counting facilities - the BRR in Budapest and the FRM II in Garching near Munich. Employing cold neutrons, resonance neutron capture by low energetic resonances was avoided during the experiments. This is an improvement over older neutron activation based works at thermal reactor neutron energies. 152 prompt γ-rays of 237Np were identified, as well as 19 of 241Am, and 127 prompt γ-rays of 242Pu. In all cases, both high and lower energetic prompt γ-rays were identified. The most intense line of 237Np was observed at an energy of Eγ=182.82(10) keV associated with a partial capture cross section of σγ=22.06(39) b. The most intense prompt γ-ray lines of 241Am and of 242Pu were observed at Eγ=154.72(7) keV with σγ=72.80(252) b and Eγ=287.69(8) keV with σγ=7.07(12) b, respectively. The measurements described in this thesis provide the first reported quantifications on partial radiative capture cross sections for 237Np, 241Am and 242Pu measured simultaneously over the large energy range from 45 keV to 12 MeV. Detailed uncertainty assessments were performed and the validity of the given uncertainties was demonstrated. Compared

  6. ZZ FSXJ32, MCNP nuclear data library based on JENDL-3.2. ZZ FSXLIBJ33, MCNP nuclear data library based on JENDL-3.3

    -103, Rh-105, Pd-102, Pd-104, Pd-105, Pd-106, Pd-107, Pd-108, Pd-110, Ag-107, Ag-109, Ag-110m,Cd-106, Cd-108, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-116, In-113, In-115, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-124, Sn-126, Sb-121, Sb-123, Sb-124, Sb-125, Te-120, Te-122, Te-123, Te-124, Te-125, Te-126, Te-127m,Te-128, Te-129m,Te-130, I -127, I -129, I -131, Xe-124, Xe-126, Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, Xe-133, Xe-134, Xe-135, Xe-136, Cs-133, Cs-134, Cs-135, Cs-136, Cs-137, Ba-130, Ba-132, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, Ba-140, La-138, La-139, Ce-140, Ce-141, Ce-142, Ce-144, Pr-141, Pr-143, Nd-142, Nd-143, Nd-144, Nd-145, Nd-146, Nd-147, Nd-148, Nd-150, Pm-147, Pm-148, Pm-148m,Pm-149, Sm-144, Sm-147, Sm-148, Sm-149, Sm-150, Sm-151, Sm-152, Sm-153, Sm-154, Eu-151, Eu-152, Eu-153, Eu-154, Eu-155, Eu-156, Gd-152, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, Tb-159, Er-162, Er-164, Er-166, Er-167, Er-168, Er-170, Hf-174, Hf-176, Hf-177, Hf-178, Hf-179, Hf-180, Ta-181, W-182, W-183, W-184, W-186, Hg-196, Hg-198, Hg-199, Hg-200, Hg-201, Hg-202, Hg-204, Pb-204, Pb-206, Pb-207, Pb-208, Bi-209, Ra-223, Ra-224, Ra-225, Ra-226, Ac-225, Ac-226, Ac-227, Th-227, Th-228, Th-229, Th-230, Th-232, Th-233, Th-234, Pa-231, Pa-232, Pa-233, U-232, U-233, U-234, U-235, U-236, U-237, U-238, Np-235, Np-236, Np-237, Np-238, Np-239, Pu-236, Pu-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Pu-244, Pu-246, Am-241, Am-242, Am-242m, Am-243, Am-244, Am-244m, Cm-240, Cm-241, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246, Cm-247, Cm-248, Cm-249, Cm-250, Bk-247, Bk-249, Bk-250, Cf-249, Cf-250, Cf-251, Cf-252, Cf-254, Es-254, Es-255, Fm-255 Temperatures: 300 K. Origin: JENDL-3.3. Thermal scattering: Free gas model Kerma factors are provided. The original JENDL-3.3 has two problems in Am-241 data. One is the missing of MF/MT=4/18, and the other is the incorrect neutron spectra for MT=18 below 500 keV. The updated data have been produced as JENDL-3

  7. ZZ VITJEF22.BOLIB, JEF-2.2 Multigroup Coupled (199 n + 42 gamma) X-Section Library in AMPX Format for Nuclear Fission Applications

    1 - Description or function: VITJEF22.BOLIB /1/ is a multigroup coupled (199 neutron groups + 42 photon groups) pseudo-problem-independent cross section library in AMPX /2/ format for nuclear fission applications. VITJEF22.BOLIB is based on the JEF-2.2 /3/ European nuclear data file and it was processed, through the NJOY /4/ and SCAMPI /5/ systems, in the VITAMIN-B6 /6/ group structure using the same parameters and calculation procedures. Original nuclear data file: JEF-2.2. Data processing systems: NJOY-94.66 and SCAMPI. Format: AMPX. Number of groups: 199 neutron groups and 42 photon groups. Thermal neutron groups: 36 groups below 5.043 eV with up-scattering cross sections. Neutron energy range: 1.0 E-5 eV - 19.64 MeV. Photon energy range: 1.0 keV - 30.0 MeV. Temperatures [K]: 300, 600, 1000, and 2100 (same values as in VITAMIN-B6). Background cross sections (SIGMA-Zeros) [barns]: 1, 10, 50, 100, 300, 1.0 E+3, 1.0 E+4, 1.0 E+5, 1.0 E+6, 1.0 E+10 (infinite dilution) (same values as in VITAMIN-B6). Legendre order: P7 for materials with Z ≤ 29 (copper); P5 for the remainders. Number of materials: 138. Materials included: one file per material (nat=natural): H-H2O, H-CH2, H2-D2O, H-3, He-3, He-4, Li-6, Li-7, Be-9, Be-TH, B-10, B-11, C-nat, C-GPH, N-14, N-15, O-16, O-17, F-19, Na-23, Mg-nat, Al-27, Si-nat, P-31, S-32, S-33, S-34, S-36, Cl-nat, K-nat, Ca-nat, Ti-nat, V-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-nat, Ga-nat, Y-89, Zr-nat, Nb-93, Mo-nat, Ag-107, Ag-109, Cd-nat, Cd-106, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-115m, Cd-116, In-113, In-115, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-124, Sn-125, Sn-126, Ba-138, Eu-151, Eu-152, Eu-153, Eu-154, Eu-155, Hf-174, Hf-176, Hf-177, Hf-178, Hf-179, Hf-180, Ta-181, Ta-182, W-182, W-183, W-184, W-186, Re-185, Re-187, Au-197, Pb-nat, Bi-209, Th-230, Th-232, Pa-231, Pa-233, U-232, U-233, U-234, U-235, U-236

  8. Reanalysis of the gas-cooled fast reactor experiments at the zero power facility Proteus - Spectral indices

    PROTEUS is a zero power reactor at the Paul Scherrer Institute which has been employed during the 1970's to study experimentally the physics of the gas-cooled fast reactor. Reaction rate distributions, flux spectrum and reactivity effects have been measured in several configurations featuring PuO2/UO2 fuel, absorbers, large iron shields, and thorium oxide and thorium metal fuel either distributed quasi-homogeneously in the reference PuO2/UO2 lattice or introduced in the form of radial and axial blanket zones. This papers focuses on the spectral indices - including fission and capture in 232Th and 237Np - measured in the reference PuO2/UO2 lattices and their predictions with an MCNPX model specially developed for the PROTEUS-GCFR core. Predictions were obtained with JEFF-3.1 and -3.11, ENDF/B-VII.0 and VII.1, and JENDL-3.3 and -4.0. A general good agreement was demonstrated. The ratio of 232Th fission to 239Pu fission, however, was under-predicted by (8.7±2.1)% and (6.5±2.1)% using ENDF/B-VII.0 and VII.1, respectively. Finally, the capture rates in 237Np tended to be under-predicted by the JEFF and JENDL libraries, although the new cross section in JEFF-3.1.1 slightly improved the 237Np capture to 239Pu fission results (3.4±2.4)%. (authors)

  9. Modeling of neptunium(V), plutonium(IV) and americium(III) sorption on soils in the presence of humic acid

    Sorption experiments of 237Np(V)O2+, 238Pu(IV)4+ and 241Am(III)3+ onto soils in the presence of humic acid have been performed by a batch system, in order to clarify effects of humic acid on sorption of the radionuclides on soils. Soils used in the present experiments were a coastal sand which does not sorb humic acid, and an ando soil which sorbs humic acid very well and is known to have a high content of humic substances. The distribution coefficient of 237Np for both soils was not affected by the presence of humic acid, since 237Np much little interact with humic acid. The distribution coefficient of 241Am for both soils decreased as the humic acid concentration increased. Also the distribution coefficient of 238Pu for the coastal sand decreased with increasing humic acid concentration. On the other hand, as to the ando soil, the distribution coefficient of 238Pu in the presence of humic acid was larger than that in the absence of humic acid, in the humic acid concentration range below 5 mg/dm3, although it decreased with increasing humic acid concentration over 5 mg/dm3. These results suggest that apparent sorption behavior of 238Pu and 241Am on the soils may be dependent on the sorption ability of their humic complexes. The distribution coefficient of the three radionuclides for the soils could be evaluated by the sorption equilibrium model taking account of the effects of the sorption of both humic acid itself and humic complexes of radionuclide on the value of the distribution coefficient, besides the complexation in aqueous phase. (author)

  10. Distribution of Np and Pu in Swedish lichen samples (Cladonia stellaris) contaminated by atmospheric fallout

    Lindahl, Patric E-mail: patric.lindahl@radfys.lu.se; Roos, Per; Eriksson, Mats; Holm, Elis

    2004-07-01

    The activity concentrations of {sup 237}Np and the two Pu isotopes, {sup 239}Pu and {sup 240}Pu, were determined in lichen samples (Cladonia stellaris) contaminated by fallout from atmospheric nuclear test explosions and the Chernobyl accident. The samples were collected at 18 locations in Sweden, from north to south, between 1986 and 1988 and analysed with high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and alpha spectrometry. Data on the activity ratios {sup 238}Pu/{sup 239+240}Pu and {sup 134}Cs/{sup 137}Cs measured previously were also included in this study for comparison. The {sup 237}Np activity concentration ranged from 0.08{+-}0.01 to 2.08{+-}0.17 mBq kg{sup -1}, depending on the location of the sampling site and time of collection. The {sup 239+240}Pu activity concentration ranged from 0.09{+-}0.01 to 4.09{+-}0.15 Bq kg{sup -1}, with the {sup 240}Pu/{sup 239}Pu atomic ratio ranging between 0.16{+-}0.01 and 0.44{+-}0.03, the higher ratios indicating a combination of weapons test fallout and Chernobyl fallout. The {sup 237}Np/{sup 239}Pu atomic ratios ranged between 0.06{+-}0.01 and 0.42{+-}0.04, the lower ratios indicating combination of weapons test fallout and Chernobyl fallout. At a well-defined sampling site at Lake Rogen (62.32 deg. N, 12.38 deg. E), additional lichen samples were collected between 1987 and 1998 to study the distribution of Np and Pu in different layers. The concentrations of the two elements follow each other quite well in the profile.

  11. Reanalysis of the Gas-cooled fast reactor experiments at the zero power facility Proteus – Spectral indices

    Girardin G.

    2013-03-01

    Full Text Available PROTEUS is a zero power reactor at the Paul Scherrer Institute which has been employed during the 1970’s to study experimentally the physics of the gas-cooled fast reactor. Reaction rate distributions, flux spectrum and reactivity effects have been measured in several configurations featuring PuO2/UO2 fuel, absorbers, large iron shields, and thorium oxide and thorium metal fuel either distributed quasihomogeneously in the reference PuO2/UO2 lattice or introduced in the form of radial and axial blanket zones. This papers focus on the spectral indices – including fission and capture in 232Th and 237Np - measured in the reference PuO2/UO2 lattices and their predictions with an MCNPX model specially developed for the PROTEUS-GCFR core. Predictions were obtained with JEFF-3.1 and -3.11, ENDF/B-VII.0 and VII.1, and JENDL-3.3 and -4.0. A general good agreement was demonstrated. The ratio of 232Th fission to 239Pu fission, however, was under-predicted by 8.7±2.1% and 6.5±2.1% using ENDF/B-VII.0 and VII.1, respectively. Finally, the capture rates in 237Np tended to be underpredicted by the JEFF and JENDL libraries, although the new cross section in JEFF-3.1.1 slightly improved the 237Np capture to 239Pu fission results (3.4±2.4%.

  12. Determination of 236Np(n,f) cross-section using surrogate ratio method

    Surrogate strategy is widely used to determine (n,f) cross-sections. Hybrid ratio approach is used to get 236Np(n,f) cross-section for which there is no experimental data available beyond 7 MeV till date. 237Np and 239Pu are produced over the similar excitation energy range (20.4-25.4 MeV) using 235U(6Li,α)237Np and 235U(6Li,d)239Pu reactions respectively. The ground state Q values for these two reactions are 7.707 MeV and - 6.718 respectively. Hence 237Np and 239Pu can be populated at overlapping excitation energies in 6Li + 235U transfer reactions for bombarding energies around 44.4 MeV. Fission probabilities of these two compound nuclei are measured and the desired cross-sections are determined using the following formula based on Weisskopf-Ewing approximation. Measurements were carried out using 44.4 MeV 6Li beam (from BARC-TIFR Pelletron) and 1.6 mg/cm2 thick 235U target (with 4.5 mg/cm2 thick Ni-Cu backing). Four telescopes (ΔE-E) made of silicon surface barrier detectors, used to detect light charged particles, were kept 100 apart covering 700-1000. A large area silicon detector (with a solid angle ∼ 33 msr and an angular coverage of 1540- 1660) was used to detect fission fragments. Two monitor detectors were placed at forward angles. Results for 236Np(n,f) cross sections using the yields from the forward most telescope are shown. Contributions from Ni-Cu backing in inclusive counts have been subtracted out. The experimental results are consistent with the EMPIRE3.1 calculations

  13. Radionuclide Transport in Fracture-Granite Interface Zones

    Hu, Q; Mori, A

    2007-09-12

    In situ radionuclide migration experiments, followed by excavation and sample characterization, were conducted in a water-conducting shear zone at the Grimsel Test Site (GTS) in Switzerland to study diffusion paths of radionuclides in fractured granite. In this work, we employed a micro-scale mapping technique that interfaces laser ablation sampling with inductively coupled plasma-mass spectrometry (LA/ICP-MS) to measure the fine-scale (micron-range) distribution of actinides ({sup 234}U, {sup 235}U, and {sup 237}Np) in the fracture-granite interface zones. Long-lived {sup 234}U, {sup 235}U, and {sup 237}Np were detected in flow channels, as well as in the adjacent rock matrix, using the sensitive, feature-based mapping of the LA/ICP-MS technique. The injected sorbing actinides are mainly located within the advective flowing fractures and the immediately adjacent regions. The water-conducting fracture studied in this work is bounded on one side by mylonite and the other by granitic matrix regions. These actinides did not penetrate into the mylonite side as much as the relatively higher-porosity granite matrix, most likely due to the low porosity, hydraulic conductivity, and diffusivity of the fracture wall (a thickness of about 0.4 mm separates the mylonite region from the fracture) and the mylonite region itself. Overall, the maximum penetration depth detected with this technique for the more diffusive {sup 237}Np over the field experimental time scale of about 60 days was about 10 mm in the granitic matrix, illustrating the importance of matrix diffusion in retarding radionuclide transport from the advective fractures. Laboratory tests and numerical modeling of radionuclide diffusion into granitic matrix was conducted to complement and help interpret the field results. Measured apparent diffusivity of multiple tracers in granite provided consistent predictions for radionuclide transport in the fractured granitic rock.

  14. Comparison of fission and capture cross sections of minor actinides

    The fission and capture cross sections of minor actinides given in JENDL-3.3 are compared with other evaluated data and experimental data. The comparison was made for 32 nuclides of Th-227, 228, 229, 230, 233, 234, Pa-231, 232, 233, U-232, 234, 236, 237, Np-236, 237, 238, Pu-236, 237, 238, 242, 244, Am-241, 242, 242m, 243, Cm-242, 243, 244, 245, 246, 247 and 248. Given in the present report are figures of these cross sections and tables of cross sections at 0.0253 eV and resonance integrals. (author)

  15. Neutron-induced fission cross section of 240,242Pu up to En = 3 MeV

    SALVADOR CASTINEIRA PAULA; BRYS TOMASZ; Hambsch, Franz-Josef; Oberstedt, Stephan; Pretel, C.; Vidali, Marzio

    2014-01-01

    The neutron-induced fission cross sections of 240,242Pu have been measured at JRC-IRMM with incident neutron energy from 0.2 MeV up to 3 MeV. A Twin-Frisch Grid Ionization Chamber (TFGIC) has been used in a back-to-back geometry. The measurements have been performed using the secondary standards 237Np and 238U as a reference. The purity of the plutonium samples was 99.89% for 240Pu and 99.97% for 242Pu. The results obtained follow the ENDF/B-VII.1 evaluation for 240Pu, but some discrepancies ...

  16. On the role of energy separated in fission process, excitation energy and reaction channels effects in the isomeric ratios of fission product 135Xe in photofission of actinide elements

    Thiep, Tran Duc; An, Truong Thi; Cuong, Phan Viet; Vinh, Nguyen The; Mishinski, G. V.; Zhemenik, V. I.

    2016-07-01

    In this work we present the isomeric ratio of fission product 135Xe in the photo-fission of actinide elements 232Th, 233U and 237Np induced by end-point bremsstrahlung energies of 13.5, 23.5 and 25.0 MeV which were determined by the method of inert gaseous flow. The data were analyzed, discussed and compared with the similar data from literature to examine the role of energy separated in fission process, excitation energy and reaction channels effects.

  17. Neutron-induced fission cross section of 240,242Pu

    Salvador Castiñeira, Paula

    2014-01-01

    A recent sensitivity analysis done for the new generation of fast reactors [1] has shown the importance of improved cross section data for several actinides. Among them, the neutron-induced fission cross section of 240,242Pu requires a level of accuracy of 1-3% and 3-5%, respectively, from the current status of 6% and 20%. Moreover, nearly all the measurements in the literature have been done relative to 235U(n,f). Therefore, using other references samples such as 237Np or 238U will provide t...

  18. Effects of the shape of tracer source on 90Sr migration

    The method and the results of the tracer migration test in horizontal column, which was conducted in the experimental shaft of the CIRP's Field Test Site, are introduced. The effects of the shape of tracer source on 90Sr migration are discussed. The results indicates that adsorption capacity of loess to 90Sr, 237Np, 238Pu and 241Am are relatively strong. Humus retarded migration of 90Sr. Retardation coefficient of 90Sr, under the condition of plane source, is less than that under the condition of point source. (authors)

  19. A certified reference material for radionuclides in the water sample from Irish Sea (IAEA-443)

    Pham, M.K.; Betti, M.; Povinec, P.P.;

    2011-01-01

    A new certified reference material (CRM) for radionuclides in sea water from the Irish sea (IAEA-443) is described and the results of the certification process are presented. Ten radionuclides (3H, 40K, 90Sr, 137Cs, 234U, 235U, 238U, 238Pu, 239+240Pu and 241Am) have been certified, and information...... values on massic activities with 95% confidence intervals are given for four radionuclides (230Th, 232Th, 239Pu and 240Pu). Results for less frequently reported radionuclides (99Tc, 228Th, 237Np and 241Pu) are also reported. The CRM can be used for quality assurance/quality control of the analysis of...

  20. Metabolism and toxicity of neptunium

    The biological behavior and toxicity of neptunium were studied. Neptunium was admimistered either intravenously or intramuscularly in rats. In contrast of other transuranium elements the distribution patterns of neptunium in case of intravenous injection is not dependent of the physico-chemical state. The urinary excretion is high. The distribution after intramuscular injection showed a rather fast migration from the injection site. 237Np excreted in urine was approximately equal to bone deposit. Neptunium behavior rather followed that of alkaline earths than that of transplutonium elements

  1. Activation Spectrometry of Fast Neutrons by IAEA Threshold Detectors at Neutron Generators

    The suitability of the IAEA set of threshold detectors for neutron accident purposes was investigated. A generator producing 14.3-MeV neutrons by the T(d, n)4He reaction was employed for this purpose. 237Np, 232Th, 58Ni and 27Al threshold detectors were used. The induced activity was determined by gamma spectrometry using a multichannel analyser. Fast neutron spectra have been estimated from the experimental results. Measurements at the surface and at the depth of a phantom were provided. Some difficulties from low induced and fission activities (caused by the small neutron flux density and the light weight of the detectors) are pointed out. (author)

  2. Sorption of Np (V) by U (VI) hydroxide solids

    Wruck, D A; Brachmann, A; Sylwester, E; Allen, C E A

    1999-09-20

    The distribution of {sup 237}Np(V) between aqueous NaHCO{sub 3} solutions and U(VI) hydroxide solids was investigated. Experiments were initiated by addition of U solids to Np solutions and by coprecipitation of U and Np. Analysis by U L{sub III} extended X-ray absorption fine structure (EXAFS) spectroscopy and infrared absorption spectroscopy indicated the solid phase was synthetic schoepite. Equilibrium Np distribution coefficients were 5-44 mL/g in the pH range 6-8. The results are consistent with adsorption of Np by the solids and provide no evidence of Np incorporation in the bulk solid.

  3. EDB-II validated, key fission product yields for fast reactor application

    Relative fission yields were measured for three different locations in the row 4 ''Test Region'' of the EBR-II reactor. Correlation of the relative fission yields to the measured average energy (anti E) and the measured 137Cs 238U/235U spectral indices have been made. The measured relative fission yields for selected fission products from 235U, 238U, 239Pu and 237Np have been compared with those values reported by the Interlaboratory Reaction Rate (ILRR) program, EBR-II fast reactor yields from destructive analysis and summation, and the March 1977 version of ENDF/B-V

  4. Simultaneous neutron and gamma spectrum adjustment

    The spectrum adjustment procedure was extended to simultaneous neutron and gamma spectrum adjustment, and the feasibility of this technique is demonstrated in the analysis of HFIR dosimetry experiments. Conditions in which gamma rays may contribute considerably to radiation damage in steels are discussed. Beryllium helium accumulation fluence monitors (HAFMs) were found to be good monitors in gamma fields of intensities high enough to contribute to steel embrittlement. Use of 237Np, 238U, and 9Be HAFM as gamma dosimeters is proposed for high-dose irradiations in high-energy, high-intensity gamma fields

  5. The nuclear excitation by electron transition (NEET) and its application to isotope separation

    The electron transition in atoms can excite nuclei under the particular condition, and the possibility of its application to isotope separation has been studied. The theory and the experiment are shown in this paper. The NEET of 189Os was first confirmed at Osaka University, and that of 237Np was carried out in succession. Though the application to isotope separation has not been established so far, the separation of 235U from 238U is very interesting. The possibility of the above isotope separation is discussed. (Yoshimori, M.)

  6. Marine Biological Investigations at the Eniwetok Test Site

    The results of marine biological investigations conducted at the Eniwetok Test Site since 1952 are summarized. Radioisotopes introduced into the sea from the tests at various times since then include fission products and other radioisotopes (U237, Np239, Mn54, Fe55,59, Co57,58,60, Zn65 and W185). The levels of radioisotopes in plankton samples taken 4 days to 6 weeks after contamination are reported and the distribution of the radioactivity between plankton and water is given. Grazing fishes contained Zn65, Fe55, Co57,58,60 and Mn54. Carnivorous fishes contained mostly Fe55 and Zn65. (author)

  7. Fission fragment angular distribution in heavy ion induced fission

    S. Soheyli

    2006-06-01

    Full Text Available   We have calculated the fission fragment angular anisotropy for 16O + 232Th,12C + 236U , 11B + 237 Np , 14 N + 232 Th , 11B + 235U , 12C + 232Th systems with the saddle point statistical model and compared the fission fragment angular anisotropy for these systems. This comparison was done with two methods a without neutron correction and b with neutron correction. Also we studied normal and anomalous behavior of the fission fragment angular anisotropy. Finally, we have predicted the average emitted neutron from compound nuclei considering the best fit for each system.

  8. Modelling of reaction cross sections and prompt neutron emission

    Oberstedt S.

    2010-10-01

    Full Text Available Accurate nuclear data concerning reaction cross sections and the emission of prompt fission neutrons (i.e. multiplicity and spectra as well as other fission fragment data are of great importance for reactor physics design, especially for the new Generation IV nuclear energy systems. During the past years for several actinides (238U(n, f and 237Np(n, f both the reaction cross sections and prompt neutron multiplicities and spectra have been calculated within the frame of the EFNUDAT project.

  9. Fission fragment angular distribution in heavy ion induced fission

    S. Soheyli; I. Ziaeian

    2006-01-01

      We have calculated the fission fragment angular anisotropy for 16O + 232Th,12C + 236U , 11B + 237 Np , 14 N + 232 Th , 11B + 235U , 12C + 232Th systems with the saddle point statistical model and compared the fission fragment angular anisotropy for these systems. This comparison was done with two methods a) without neutron correction and b) with neutron correction. Also we studied normal and anomalous behavior of the fission fragment angular anisotropy. Finally, we have predicted the averag...

  10. Photonuclear measurements on fissionable isotopes using monoenergetic photons

    The LLL linac monochromatic photon facility is used for measurements, which to date have included at least some data on the eight isotopes: 232Th, 233U, 234U, 235U, 236U, 237Np, 238U, and 239Pu. Photofission events are determined from an analysis of the emitted neutron multiplicity distributions as determined with the LLL 4π neutron detector. A sampling of data taken to date is included and is organized as follows: low-energy photofission cross sections, neutrino and fission neutron multiplicity distribution width parameter data, ring-ratio multiplicity coincidence data, delayed-neutron fraction data, and photonuclear and photofission cross sections. 2 refs., 32 figs

  11. Determination of 236Np(n,f) and 238Pu(n,f) cross-sections using surrogate reactions

    Cross sectional data for 236Np(n,f) reaction is not available for neutron energies beyond 4.32 MeV. In this work, we have determined the cross-section of the above reaction for the neutron energy range En=10-18 MeV using ‘Hybrid Surrogate Ratio’ method via 235U(6Li, α)237Np and 235U(6Li,d)239Pu reactions. The cross-sections for 238Pu(n,f) reaction available in literature have been used as a reference for the above surrogate method

  12. INERT-MATRIX FUEL: ACTINIDE ''BURNING'' AND DIRECT DISPOSAL

    Excess actinides result from the dismantlement of nuclear weapons (Pu) and the reprocessing of commercial spent nuclear fuel (mainly 241 Am, 244 Cm and 237 Np). In Europe, Canada and Japan studies have determined much improved efficiencies for burnup of actinides using inert-matrix fuels. This innovative approach also considers the properties of the inert-matrix fuel as a nuclear waste form for direct disposal after one-cycle of burn-up. Direct disposal can considerably reduce cost, processing requirements, and radiation exposure to workers

  13. Preparation and characterisation of 234U tracer for mass spectrometry and alpha spectrometry

    234U was milked from 15 years aged 238Pu prepared earlier by neutron irradiation of 237Np. Ion exchange procedure using Dowex 1 X 8 resin in the nitric acid medium was followed for this purpose, in a glove box. The purified 234U was characterised by alpha spectrometry and thermal ionisation mass spectrometry for its 238Pu content and the isotopic composition of uranium, respectively. Alpha activity ratio of 234U/238Pu was 0.015 and the abundance of 234U was about 99 atom percent. (author). 1 fig

  14. Speciation of Long-Lived Radionuclides in the Environment

    Hou, Xiaolin

    , isotopes of Pu, and 237Np in seawater, fresh water, soil, sediment, vegetations, and concrete. The developed methods are used for the investigation of the chemical speciation of these radionuclides as well as their environmental behaviours, especially in Danish environment. In addition the speciation of Pu......This project started in November 2005 and ended in November 2008, the work and research approaches are summarized in this report. This project studied the speciation of radionuclides in environment. A number of speciation analytical methods are developed for determination of species of 129I, 99Tc...

  15. Challenge in determination of long-lived radionuclides by ICP-MS

    The ultra-trace and isotope analysis of long-lived radionuclides in environmental materials (in biological or geological samples and waters) is relevant of increasing importance [1-5].E.g., the determination of long-lived radionuclides is for the detection of radionuclide contamination in environmental materials in which several radioactive nuclides (e.g.99Tc, 129I , 237Np, 239Pu, 240Pu, 241Am) are present from fallout due to nuclear weapons testing, nuclear power plants or nuclear accidents. Especially, isotope ratios of uranium and plutonium [6] can indicate the origin of contamination in the environmental samples

  16. Application of inductively coupled plasma mass spectrometry to the measurement of long-lived radionuclides in environmental samples

    This review describes applications of inductively coupled plasma mass spectrometry (ICP-MS) to the determination of long-lived radionuclides in environmental samples. Simultaneous determination of 232Th and 238U in biological samples is described in detail; in this procedure an internal standard, Tl or Bi, is adopted for correction of the matrix effect. Determination of 237Np in soil samples by ICP-MS is also described. It is chemically separated to ensure no interference from matrix elements. The detection limits are several mBq (several pg) for the case of radionuclides having a half life of thirty or forty thousand years. (author)

  17. Alpha self-irradiation effects in ternary oxides of actinides elements: The zircon-like phases AmIIIVO4 and AIINpIV(VO4)2 (A=Sr, Pb)

    We report the experimental studies of irradiation damage from alpha decay in neptunium and americium vanadates versus cumulative dose. The isotopes used were the transuranium α-emitter 237Np and the α,γ-emitter 241Am. Neptunium and americium vanadates self-irradiation was studied by X-ray diffraction method (XRD). The comparison of the powder diffraction patterns reveal that the irradiation has no apparent effect on the neptunium phases while the americium vanadate swells and becomes metamict as a function of cumulative dose

  18. Calculation of waste disposal rating for the fusion experimental breeder FEB-E

    Using the neutron transport code BISON 3.0, activation calculation code FDKR and its associated data libraries, the activation calculation and analyses of all long-lived radionuclides are performed for the Fusion Experimental Breeder FEB-E. The results indicate that the first wall and blanket structure materials of the FEB-E can meet the nuclear waste disposal criteria for the NRC 10CFR61 Class C after a few weeks from shutdown. The inventory of important actinides during field reprocessing, such as 232U and 237Np, are also calculated. Their concentrations do not excess the limit value required for environmental safety

  19. Comparison of fission and capture cross sections of minor actinides

    Nakagawa, T

    2003-01-01

    The fission and capture cross sections of minor actinides given in JENDL-3.3 are compared with other evaluated data and experimental data. The comparison was made for 32 nuclides of Th-227, 228, 229, 230, 233, 234, Pa-231, 232, 233, U-232, 234, 236, 237, Np-236, 237, 238, Pu-236, 237, 238, 242, 244, Am-241, 242, 242m, 243, Cm-242, 243, 244, 245, 246, 247 and 248. Given in the present report are figures of these cross sections and tables of cross sections at 0.0253 eV and resonance integrals.

  20. Systematics of fission cross sections at the intermediate energy region

    Fukahori, Tokio; Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    The systematics was obtained with fitting experimental data for proton induced fission cross sections of Ag, {sup 181}Ta, {sup 197}Au, {sup 206,207,208}Pb, {sup 209}Bi, {sup 232}Th, {sup 233,235,238}U, {sup 237}Np and {sup 239}Pu above 20 MeV. The low energy cross section of actinoid nuclei is omitted from systematics study, since the cross section has a complicated shape and strongly depends on characteristic of nucleus. The fission cross sections calculated by the systematics are in good agreement with experimental data. (author)

  1. HEU age determination

    A technique has been developed to determine the Highly Enriched Uranium (HEU) Age which is defined as the time since the HEU was produced in an enrichment process. The HEU age is determined from the ratios of relevant uranium parents and their daughters viz 230Th/234U and 231Pa/235U. Uranium isotopes are quantitatively measured by their characteristic gammas and their daughters by alpha spectroscopy. In some of the samples where HEU is enriched more than 99%, the only mode of HEU age determination is by the measurement of 231Pa since there is negligible quantity of 230Th due to very low atom concentrations of 234U in the sample. In this paper we have presented data and methodology of finding the age of two HEU samples

  2. Mound Facility activities in chemical and physical research: July-December 1979

    1980-06-18

    Research is reported in the following fields: isotope separation (Ar, C, He, Kr, Ne, O, Xe), low-temperature research (H intermolecular potential functions, gas analysis in trennschaukel), separation chemistry (/sup 229/Th, /sup 231/Pa, /sup 230/Th, /sup 234/U), separation research (liquid thermal diffusion, Ca isotope separation, molecular beam scattering, mutual diffusion of noble gas mixtures, lithium chemical exchange with cryptands), and calculations in plutonium chemistry (algorithms, valence in natural water). (DLC)

  3. Study for 228Th reduction in thermal reactor with Th-U fuel cycls

    1999-01-01

    By using computercode WIMS/CENDL, the effects of some parameters, core configuration such as fuel element structure, neutron flux and burn-up, are discussed in thispaper.It is shown that high neutron flux, small fuel rod diameter,large volume ratio of coolant to fuel, seed-blank heterogeneous corearrangement and 231Pa chemical separation are necessary for reducing 228Th production in reactor.

  4. Analysis for the radionuclides of the natural uranium and thorium decay chains with special reference to uranium mine tailings

    A detailed review is made of the experimental techniques that are available, or are in the process of development, for the determination of 238U, 235U, 234U, 231Pa, 232Th, 230Th, 228Th, 228Ra, 226Ra, 223Ra, 210Po and 210Pb. These products of the uranium and thorium decay chains are found in uranium mine tailings. Reference is also made to a procedure for the selective phase extraction of mineral phases from uranium mine tailings

  5. Mound Facility activities in chemical and physical research: July-December 1979

    Research is reported in the following fields: isotope separation (Ar, C, He, Kr, Ne, O, Xe), low-temperature research (H intermolecular potential functions, gas analysis in trennschaukel), separation chemistry (229Th, 231Pa, 230Th, 234U), separation research (liquid thermal diffusion, Ca isotope separation, molecular beam scattering, mutual diffusion of noble gas mixtures, lithium chemical exchange with cryptands), and calculations in plutonium chemistry (algorithms, valence in natural water)

  6. Measurements of radium in water using impregnated fibers

    The technique perfected by Moore and Reid for sampling radium in seawater is well adapted for environmental sampling. Using this method, we have examined runoff from mine tailings and have observed relatively high amounts of 223Ra (from the 235U series). Apparently the fiber is able to absorb a precursor, 231Pa or 227Ac, and hence retains the 223Ra concentrations for long storage periods. Examples of high-resolution alpha spectrometry of these activities are presented

  7. Design study of Thorium-232 and Protactinium-231 based fuel for long life BWR

    Trianti, N.; Su'ud, Z.; Riyana, E. S.

    2012-06-01

    A preliminary design study for the utilization of thorium added with 231Pa based fuel on BWR type reactor has been performed. In the previous research utilization of fuel based Thorium-232 and Uranium-233 show 10 years operation time with maximum excess-reactivity about 4.075% dk/k. To increase reactor operation time and reduce excess-reactivity below 1% dk/k, Protactinium (Pa-231) is used as Burnable Poison. Protactinium-231 has very interesting neutronic properties, which enable the core to reduce initial excess-reactivity and simultaneously increase production of 233U to 231Pa in burn-up process. Optimizations of the content of 231Pa in the core enables the BWR core to sustain long period of operation time with reasonable burn-up reactivity swing. Based on the optimization of fuel element composition (Th and Pa) in various moderation ratio we can get reactor core with longer operation time, 20 ˜ 30 years operation without fuel shuffling or refuelling, with average power densities maximum of about 35 watt/cc, and maximum excess-reactivity 0.56% dk/k.

  8. 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

  9. Transuranium reference measurements and reference materials

    During the 30 years of its existence, the Central Bureau for Nuclear Measurements has been involved in numerous high-accuracy investigations of mainly nuclear properties of elements important for the nuclear fuel cycle and for application of relevant radionuclides. This paper reports that these studies were made possible by the availability of particle accelerators (150-MeV electron linear accelerator; 3.7- and 7-MV Van de Graaff accelerators) as neutron sources and the use of specialized laboratories for the preparation, characterization, and manipulation of radioactive samples. Examples of investigations with plutonium and neptunium are capture and fission cross sections of 239Pu at very low energies, spontaneous fission fragment mass and energy distributions of 242Pu at very low energies, spontaneous fission fragment mass and energy distributions of 242Pu, alpha-particle and gamma-ray spectra of 237Np, half-life of 241Pu, use of 237Np in reactor neutron dosimetry, preparation and characterization of plutonium oxide reference materials for nondestructive analysis, and demonstration of the potential of synthetic isotope mixtures for analytical control of the nuclear fuel cycle

  10. EA-MC Neutronic Calculations on IAEA ADS Benchmark 3.2

    The neutronics and the transmutation properties of the IAEA ADS benchmark 3.2 setup, the 'Yalina' experiment or ISTC project B-70, have been studied through an extensive amount of 3-D Monte Carlo calculations at CERN. The simulations were performed with the state-of-the-art computer code package EA-MC, developed at CERN. The calculational approach is outlined and the results are presented in accordance with the guidelines given in the benchmark description. A variety of experimental conditions and parameters are examined; three different fuel rod configurations and three types of neutron sources are applied to the system. Reactivity change effects introduced by removal of fuel rods in both central and peripheral positions are also computed. Irradiation samples located in a total of 8 geometrical positions are examined. Calculations of capture reaction rates in 129I, 237Np and 243Am samples and of fission reaction rates in 235U, 237Np and 243Am samples are presented. Simulated neutron flux densities and energy spectra as well as spectral indices inside experimental channels are also given according to benchmark specifications. Two different nuclear data libraries, JAR-95 and JENDL-3.2, are applied for the calculations

  11. Capture cross section measurement of Np-237 below 1 keV with Lead Slowing-down Spectrometer

    Kobayashi, Katsuhei; Cho, Hyun-Je; Yamamoto, Shuji; Yoshimoto, Takaaki; Fujita, Yoshiaki [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Ohkawachi, Yasushi [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center

    2000-03-01

    Making use of the Kyoto University Lead slowing-down Spectrometer (KULS) driven by a 46 MeV electron linear accelerator (linac) at the Research Reactor Institute, Kyoto University (KURRI), the relative cross section for the {sup 237}Np(n,{gamma}) reaction has been measured from 0.01 eV to 1 keV with energy resolution of about 40% (FWHM). The neutron flux/spectrum has been measured by a BF{sub 3} counter. The cross section of the {sup 10}B(n,{alpha}) reaction in ENDF/B-VI was used as a reference one for the cross section measurement. The measured result has been normalized to the reference value of the {sup 237}Np(n,{gamma}){sup 238}Np reaction in ENDF/B-VI at 0.0253 eV, and the measurement has been compared with the experimental and the evaluated data in ENDF/B-VI and JENDL-3.2, whose data were broadened by the energy resolution of the KULS. (author)

  12. Analytical method for the determination of Np and Pu in sea water by AMS with respect to the Fukushima accident

    Hain, K.; Faestermann, T.; Famulok, N.; Fimiani, L.; Gómez-Guzmán, J. M.; Korschinek, G.; Kortmann, F.; Lierse v. Gostomski, Ch.; Ludwig, P.; Shinonaga, T.

    2015-10-01

    A chemical separation procedure for plutonium (Pu) and neptunium (Np) was developed using extraction chromatography, mass spectrometry and radiometric analysis to determine their concentrations and isotopic ratios in sea water. 241Am, which causes isobaric background to 241Pu in mass spectrometric measurements, was successfully separated from the Pu fraction by this method. Water samples which were spiked with 242Pu and 237Np or 239Np, respectively, were used for chemical yield determination. The chemical yields of Pu and Np, which were determined by alpha and gamma spectrometry at the Radiochemie München (RCM), of more than 85% were obtained. The developed method was applied to analyze the concentration of Pu and Np in the certified reference material, IAEA-443, by Accelerator Mass Spectrometry (AMS) at the Maier-Leibnitz-Laboratory (MLL) to check the applicability of the method to sea water samples. The concentrations of 240Pu, 241Pu and 237Np obtained in this study are in agreement with the certified and literature values within the uncertainties. Due to strong isotopic interference of 239Pu with 238U, it was not possible to analyze the concentration of 239Pu. Some modifications of the chemical separation method to suppress the uranium (U) fraction are under consideration. This method can be used for the analysis of Pu and Np in Pacific Ocean water samples collected after the Fukushima accident.

  13. Moessbauer spectroscopy in neptunium compounds

    Nakamoto, Tadahiro; Nakada, Masami; Masaki, Nobuyuki; Saeki, Masakatsu [Japan Atomic Energy Research Inst., Tokyo (Japan)

    1997-03-01

    Moessbauer effects are observable in seven elements of actinides from {sup 232}Th to {sup 247}Cm and Moesbauer spectra have been investigated mainly with {sup 237}Np and {sup 238}U for the reasons of availability and cost of materials. This report describes the fundamental characteristics of Moessbauer spectra of {sup 237}Np and the correlation between the isomer shift and the coordination number of Np(V) compounds. The isomer shifts of Np(V) compounds had a tendency to increase as an increase of coordination number and the isomer shifts of Np(V) compounds showed broad distribution as well as those of Np(VI) but {delta} values of the compounds with the same coordination number were distributed in a narrow range. The {delta} values of Np(VI) complexes with O{sub x} donor set suggest that the Np atom in its hydroxide (NpO{sub 2}(OH){center_dot}4H{sub 2}O)might have pentagonal bipyramidal structure and at least, pentagonal and hexagonal bipyramidal structures might coexist in its acetate and benzoate. Really, such coexistence has been demonstrated in its nitrate, (NpO{sub 2}){sub 2}(NO{sub 3}){sub 2}{center_dot}5H{sub 2}O. (M.N.)

  14. The effects of actinide separation on the radiological consequences of geologic disposal of high-level waste

    It has often been suggested that the potential hazard to man from the disposal of high-level radioactive waste could be reduced by removing a substantial fraction of the actinide elements. In this report the effects of actinide separation on the radiological consequences of one of the disposal options currently under consideration, that of burial in deep geologic formations, are examined. The results show that the potential radiological impact of geologic disposal of high-level waste arises from both long-lived fission products and actinides (and their daughter radionuclides). Neither class of radionuclides is of overriding importance and actinide separation would therefore reduce the radiological impact to only a limited extent and over limited periods. There might be a case for attempting to reduce doses from 237Np. To achieve this it appears to be necessary to separate both neptunium and its precursor element americium. However, there are major uncertainties in the data needed to predict doses from 237Np; further research is required to resolve these uncertainties. In addition, consideration should be given to alternative methods of reducing the radiological impact of geologic disposal. The conclusions of this assessment differ considerably from those of similar studies based on the concept of toxicity indices. Use of these indices can lead to incorrect allocation of research and development effort. (author)

  15. Radionuclide migration experiments in a natural fracture in a quarried block of granite

    A radionuclide migration experiment was performed over a distance of 1 m in a natural fracture in a quarried block of granite. The fracture in the block was characterized hydraulically by measuring the pressure drop in borehole-to-borehole pump tests. The effective fracture volume in the block was ∼100 mL. A silicone coating was applied to the exterior, and the block was immersed in a tank of water to which hydrazine was added to provide a chemically reducing barrier. Migration experiments were performed at a flow rate of 2.2 mL h-1 using 85Sr, 131I,137Cs, 144Ce, 152Eu, 237Np and 238Pu. A total of 9.5 L of groundwater was pumped through the fracture, corresponding to ∼95 fracture volumes. Only 85Sr, 131I, 137Cs, 237Np and 238Pu were observed in the eluent. Scanning of the fracture surface at the end of the migration experiment showed limited mobility of α-emitting radionuclides and of the rare-earth elements, consistent with static sorption data obtained on representative fracture surface material. The mobility of 137Cs was higher than that of the rare-earth elements, but it was lower than that of 85Sr. When samples of fracture-coating material were separated into fractions with different specific gravity, there was a clear indication of radionuclide association with mineral groups. (author)

  16. Radionuclide migration experiments in a natural fracture in a quarried block of granite

    Vandergraaf, Tjalle T.; Drew, Douglas J.; Masuda, Sumio

    1996-02-01

    A radionuclide migration experiment was performed over a distance of 1 m in a natural fracture in a quarried block of granite. The fracture in the block was characterized hydraulically by measuring the pressure drop in borehole-to-borehole pump tests. The effective fracture volume in the block was ˜ 100 mL. A silicone coating was applied to the exterior, and the block was immersed in a tank of water to which hydrazine was added to provide a chemically reducing barrier. Migration experiments were performed at a flow rate of 2.2 mL h -1 using 85Sr, 131I, 137Cs, 144Ce, 152Eu, 237Np and 238Pu. A total of 9.5 L of groundwater was pumped through the fracture, corresponding to ˜95 fracture volumes. Only 85Sr, 131I, 137Cs, 237Np and 238Pu were observed in the eluent. Scanning of the fracture surface at the end of the migration experiment showed limited mobility of α-emitting radionuclides and of the rare-earth elements, consistent with static sorption data obtained on representative fracture surface material. The mobility of 137Cs was higher than that of the rare-earth elements, but it was lower than that of 85Sr. When samples of fracture-coating material were separated into fractions with different specific gravity, there was a clear indication of radionuclide association with mineral groups.

  17. Distribution of radionuclides in mussels, winkles and prawns: Pt. 2

    Under laboratory conditions mussels, winkles and prawns have exhibited the ability to accumulate 237Np, 239Pu and 241Am from both sea water and food. In general, the soft tissues involved in feeding and digestion accumulated radionuclides most effectively. In digestive glands/hepatopancreas, the site of nuclide uptake was the digestive tubules. Other active tissues were the gill and heart of the Dublin Bay prawn and the pallial complex and operculum of the winkle. The prawn's gill was the only tissue to exhibit a clear preference between food and sea water labelling media -higher accumulation occurring via sea water. Heart tissue contained enhanced levels of 239Pu relative to 237Np and 241Am. The various glandular and secretory functions of the winkle's pallial complex may account for the comparable magnitude of nuclide activities in this tissue and the digestive gland. Other mucous secretions, on the external layers of the winkle's head and foot, have been observed to accumulate radionuclides but not as efficiently as the pallial complex. The most intense α-track distributions encountered were found in the winkle's operculum, these being attributable to its chitinous nature. Despite the relatively low activities present in Ravenglass mussels and winkles, their α-autoradiographs exhibited tissue activity trends in general accordance with those obtained experimentally. This finding provides some further support for the validity of laboratory-derived information and its extrapolation to environmental conditions. (Author)

  18. Proton-induced fission of heavy nuclei at intermediate energies

    Deppman, A; Guimaraes, V; Karapetyan, G S; Balabekyan, A R; Demekhina, N A

    2013-01-01

    The intermediate energy proton-induced fission of 241Am, 238$U and 237$Np is studied. The inelastic interactions of protons and heavy nuclei are described by a CRISP model, in which the reaction proceeds in two steps. The first one corresponds fast cascade, where a series of individual particle-particle collisions occurs within the nucleus. It leaves a highly excited cascade residual nucleus, assumed to be in thermal equilibrium. Subsequently, in the second step the excited nucleus releases its energy by evaporation of neutrons and light charged particles as well. Both the symmetric and asymmetric fission are regarded, and the fission probabilities are obtained from CRISP code calculations, by means of statistical weighting factors. The fission cross sections, the fissility of the fissioning nuclei, and the number of nucleons lost by the target - before and after fission - are calculated and compared to experiments for 660 MeV protons incident on 241Am, 238$U and 237$Np. Some of the model predictions are in f...

  19. Sensitivity analysis for actinide production and depletion in fast reactors

    In sensitivity analysis of the actinide production and depletion in fast reactors, a mathematical method of calculating sensitivity coefficients is improved and simplified by combining the time-dependent generalized perturbation technique with the eigenvalue method. Numerical calculations show that the eigenvalue method is well applicable in solving the nuclide chain equation and its adjoint equation and the cylic chains in the decay scheme of the actinides can be interpreted by means of complex eigenvalues. The sensitivity coefficients of actinide production and depletion in a 1000 MWe fast reactor are strongly dependent on the type of Pu fuel used, i.e. Pu fuel from BWR or Pu fuel from the blanket of FBR. The sensitivity coefficients due to variations of capture cross sections, σsub(n,2n) of 238U, lambda sub(β) of 241Pu and lambda sub(α) of 242Cm are especially large. Sensitivity analyses for the 1000 MWe fast reactors show that higher priorily should be given to decay constants of 241Pu and 242Cm, capture cross sections of 237Np, 241Am, 243Am and 242Pu, and fission cross sections of 237Np, 242Pu, 241Am and sup(242m)Am. (author)

  20. Modelisation of the fission cross section

    The neutron cross sections of four nuclear systems (n+235U, n+233U, n+241Am and n+237Np) are studied in the present document. The target nuclei of the first case, like 235U and 239Pu, have a large fission cross section after the absorption of thermal neutrons. These nuclei are called 'fissile' nuclei. The other type of nuclei, like 237Np and 241Am, fission mostly with fast neutrons, which exceed the fission threshold energy. These types of nuclei are called 'fertile'. The compound nuclei of the fertile nuclei have a binding energy higher than the fission barrier, while for the fissile nuclei the binding energy is lower than the fission barrier. In this work, the neutron induced cross sections for both types of nuclei are evaluated in the fast energy range. The total, reaction and shape-elastic cross sections are calculated by the coupled channel method of the optical model code ECIS, while the compound nucleus mechanism are treated by the statistical models implemented in the codes STATIS, GNASH and TALYS. The STATIS code includes a refined model of the fission process. Results from the theoretical calculations are compared with data retrieved from the experimental data base EXFOR. (author)

  1. Calculations of neutron and proton induced reaction cross sections for actinides in the energy region from 10MeV to 1GeV

    Several nuclear model codes were applied to calculations of nuclear data in the energy region from 10MeV to 1GeV. At energies up to 100MeV the nuclear theory code GNASH was used for nuclear data calculation for neutrons incident for on 238U, 233-236U, 238-242Pu, 237Np, 232Th, 241-243Am and 242-247Cm. At energies from 100MeV to 1GeV the intranuclear cascade exciton model including the fission process was applied to calculations of protons and neutrons with 233U, 235U, 238U, 232Th, 232Pa, 237Np, 238Np, 239Pu, 241Am, 242Am and 242-248Cm. Determination of parameter systematics was a major effort in the present work that was aimed at improving the predictive capability of the models used. An emphasis was placed upon a simultaneous analysis of data for a variety of reaction channels for the nuclei considered, as well as of data that are available for nearby nuclei or for other incident particles. Comparisons with experimental data available on multiple reaction cross sections, isotope yields, fission cross sections, particle multiplicities, secondary particle spectra, and double differential cross sections indicate that the calculations reproduce the trends, and often the details, of the measurements data. (author) 82 refs

  2. Proliferation Resistant Fuel for Pebble Bed Modular Reactors

    Proliferation of nuclear weapons produced with power reactors plutonium has always been amajor problem of the nuclear energy industry. This includes the PebbleBed Modular Reactor(PBMR), which is a specific design of a GenIV High-Temperature Reactor (HTR), mainly due to its online refueling feature, which may be misused for the production of weapons gradeplutonium. A promising approach toward preventing the proliferation of power reactorplutoniumis to denaturate the plutonium by increasing the ratio of 238Pu to total Pu in the spentfuel(1). The 238Pu isotope is characterized by a high heat rate (approximately 567 W/kg) due to thealpha decay of the 238Pu with half-life of 87.74 yr, in addition to its high spontaneous fissionneutron emission, which is higher than that of 240Pu. Thus, the presence of 238Pu in Pu considerably complicates the design and construction of nuclear weapons based on Pu, owing tothese characteristics of 238Pu. Recent papers(2,3) show that a Pu mixture is proliferation resistant given that the weight ratio of 238Pu to Pu is larger than 6%. In this paper we have studied afeasible technique for ensuring that the 238Pu to Pu ratio, in the Pu produced in PBMR, is larger than 6% during the entire fuel cycle. Contamination of the spent fuel with 238Pu may be achieved by doping the nuclear fuel witheither 241Am or 237Np(4-13). The 238Pu isotope is obtained from both 241Am and 237Np by a neutron-capture reaction and the subsequent decay of the reaction products(13).The 237Np isotopeis by itself a potential weapons grade material. However, its large critical mass of 57±4 kg(14) andthe difficulty of extracting it from irradiated fuel elements make it impractical for weapons purposes. On the other hand, the critical mass of 241Am is smaller, i.e. 34 to 45 kg. However, withdecay heat production of 114W/kg, the critical mass becomes a heat source of 3.9 to 5.1 KW,which makes 241Am unsuitable for weapons applications(3). As a result, it is a non

  3. Identifying Sources of Non-fallout Nuclear Contamination in Hudson River Sediments by Plutonium and Neptunium isotope ratios.

    Kenna, T. C.; Chillrud, S. N.

    2002-12-01

    In an effort to identify and characterize nuclear contaminants released from sources contained within the Hudson River drainage basin, Pu isotopes and 237Np have been measured in a series of sediment cores collected from various locations within the region. During the last several decades, the Hudson River has received input of radioactive contamination from several sources. The first and most significant, has been global fallout, which was a result of atmospheric testing of nuclear weapons primarily by governments of the United States and Former Soviet Union in the 1950s and 1960s. The second, is contamination resulting from reactor releases at the Indian Point Nuclear Power Plant (IPNPP) located on the Hudson River about 35 miles north of New York City. This facility began operation in 1962. A third source of radioactive contamination to the region is contamination resulting from activities at the Knolls Atomic Power Laboratory (KAPL) located on the Mohawk River, which began operation in 1946. Our research entails identifying different sources of nuclear contamination by measurement of plutonium and neptunium isotopic ratios by inductively coupled plasma mass spectrometry (ICP-MS). The isotopic composition of a nuclear contaminant is a sensitive indicator of its origin. By comparing the isotopic composition measured in fluvial sediments to mean values reported for global fallout (i.e. 240Pu/239Pu = 0.18 ñ 0.014, 237Np/239Pu = 0.48 ñ 0.07, and 241Pu/239Pu = .00194 ñ 00028) it is possible to identify contaminants as non-fallout in origin. To date, we have analyzed selected samples from 3 sediment cores collected from the following locations: 1) the Mohawk River downstream of KAPL, 2) the Hudson River above its confluence with the Mohawk River, and 3) the lower Hudson River at a location in close proximity to IPNPP. Isotopic analysis of sediments from the Mohawk River indicates contamination that is clearly non-fallout in origin (240Pu/239Pu ranges between 0

  4. Determination of 236U and transuranium elements in depleted uranium ammunition by α-spectrometry and ICP-MS

    It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products (236U, 239Pu, 240Pu, 241Am, and 237Np) in the ammunition. In this work the analysis of actinides by α-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. 242Pu and 243Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri-n-octylamine (TNOA), with a decontamination factor higher than 106; after elution plutonium was determined by ICP-MS (239Pu and 240Pu) and α-spectrometry (239+240Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10-12 g g-1 and 2 x 10-11 g g-1. The 240Pu/239Pu isotope ratio in one penetrator sample (0.12±0.04) was significantly lower than the 240Pu/239Pu ratios found in two soil samples from Kosovo (0.35±0.10 and 0.27±0.07). 241Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 107. The concentration of 241Am in the penetrator samples was 2.7 x 10-14 g g-1 and -15 g g-1. In addition 237Np was detected at ultratrace levels. In general, ICP-MS and α-spectrometry results were in good agreement.The presence of anthropogenic radionuclides (236U, 239Pu,240Pu, 241Am, and 237Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of radionuclides are very low, their radiotoxicological effect is negligible. (orig.)

  5. Effect of reducing groundwater on the retardation of redox-sensitive radionuclides

    Rose TP

    2008-12-01

    Full Text Available Abstract Laboratory batch sorption experiments were used to investigate variations in the retardation behavior of redox-sensitive radionuclides. Water-rock compositions were designed to simulate subsurface conditions at the Nevada Test Site (NTS, where a suite of radionuclides were deposited as a result of underground nuclear testing. Experimental redox conditions were controlled by varying the oxygen content inside an enclosed glove box and by adding reductants into the testing solutions. Under atmospheric (oxidizing conditions, radionuclide distribution coefficients varied with the mineralogic composition of the sorbent and the water chemistry. Under reducing conditions, distribution coefficients showed marked increases for 99Tc (from 1.22 at oxidizing to 378 mL/g at mildly reducing conditions and 237Np (an increase from 4.6 to 930 mL/g in devitrified tuff, but much smaller variations in alluvium, carbonate rock, and zeolitic tuff. This effect was particularly important for 99Tc, which tends to be mobile under oxidizing conditions. A review of the literature suggests that iodine sorption should decrease under reducing conditions when I- is the predominant species; this was not consistently observed in batch tests. Overall, sorption of U to alluvium, devitrified tuff, and zeolitic tuff under atmospheric conditions was less than in the glove-box tests. However, the mildly reducing conditions achieved here were not likely to result in substantial U(VI reduction to U(IV. Sorption of Pu was not affected by the decreasing Eh conditions achieved in this study, as the predominant sorbed Pu species in all conditions was expected to be the low-solubility and strongly sorbing Pu(OH4. Depending on the aquifer lithology, the occurrence of reducing conditions along a groundwater flowpath could potentially contribute to the retardation of redox-sensitive radionuclides 99Tc and 237Np, which are commonly identified as long-term dose contributors in the risk

  6. Estimation of neptunium in uranium product

    Neptunium- 237 is a long-lived (t1/2 = 2.14 x 106 years) alpha emitter, present in low concentration levels in process solutions. The oxidation state and the nature of species present in process solutions depend upon the concentration of nitrous acid, nitric acid, other redox elements, and ageing. Owing to the complicated redox behavior, 237Np is usually distributed in all streams such as highly active raffinate, plutonium product, and uranium product etc. Estimation of neptunium in various PUREX process streams is necessary for understanding the path and routing of neptunium during reprocessing of fast reactor fuels. Various methods such as neutron activation analysis (NAA), spectrophotometry and electroanalytical techniques have - been reported for quantitative estimation of neptunium in the process streams. The sample of uranium product was received from Reprocessing Group, IGCAR to estimate the concentration of neptunium in uranium product. About 1 gram of the sample was dissolved in 8 M HNO3 and evaporated to dryness. Then, the product was redissolved in 1 M HNO3, and centrifuged. The supernatant solution (1 mL) was analyzed by gamma spectrometry, alpha spectrometry and neutron activation analysis. The gamma emission of 233Pa, which was in secular equilibrium with the parent 237Np was determined for estimating of neptunium by gamma spectrometry. Analysis of the sample by alpha spectrometry showed the presence of plutonium and americium in the uranium product. These alpha emitters hindered the analysis of neptunium. Hence, Np(IV) was separated from other actinides by extraction into 1 mL of 0.5 M TTA/xylene and stripped with 10 M HNO3. An aliquot (0.1 mL) of organic phase was dried in an aluminum foil and irradiated at KAMINI reactor at the neutron flux of 1010 neutrons/cm/sec for 4 hours. The activation product, 238Np, formed was monitored by the characteristic gamma emissions at 984 keY and 1028 keY. The stripped solution was subjected to alpha spectrometry

  7. Measurements of fast neutron-induced fission data of Np-237

    Win, Than; Saito, Keiichiro; Baba, Mamoru; Iwasaki, Tomohiko; Ibaraki, Masanobu; Miura, Takako; Sanami, Toshiya; Nauchi, Yasushi; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1998-03-01

    We have performed the following measurements for {sup 237}Np using the 4.5 MV Dynamitron accelerator of Tohoku University as the pulsed neutron source: (1) Prompt fission neutron spectrum for 0.62 MeV incident neutrons, and (2) Neutron-Induced fission cross-section between 10 and 100 keV. The prompt fission neutron spectrum was measured using TOF method with a heavily shielded NE213 scintillation detector. The Maxwellian temperature T{sub m} derived is 1.28 MeV, which is lower than that of 1.38 MeV in JENDL-3.2. The fission cross sections were measured between 10 - 100 keV. The results are between JENDL-3.2 and ENDF/B-VI. (author)

  8. Fabrication and characterization of MCC [Materials Characterization Center] approved testing material---ATM-2, ATM-3, and ATM-4 glasses

    Materials Characterization Center glasses ATM-2, ATM-3, and ATM-4 are designed to simulate high-level waste glasses that are likely to result from the reprocessing of commercial nuclear reactor fuels. The three Approved Testing Materials (ATMs) are borosilicate glasses based upon the MCC-76-68 glass composition. One radioisotope was added to form each ATM. The radioisotopes added to form ATM-2, ATM-3, and ATM-4 were 241Am, 237Np, and 239Pu, respectively. Each of the ATM lots was produced in a nominal lot size of 450 g from feed stock melted in a nitrogen-atmosphere glove box at 1200/degree/C in a platinum crucible. Each ATM was then cast into bars. Analyzed compositions of these glasses are listed. The nonradioactive elements were analyzed by inductively coupled argon plasma atomic emission spectroscopy (ICP), and the radioisotope analyses were done by alpha energy analysis. Results are discussed. 7 refs., 3 figs., 5 tabs

  9. Application of Moessbauer spectroscopy to the study of neptunium adsorbed on deep-sea sediments

    A Neptunium Moessbauer spectrometer (the first in Great Britain) was constructed and the Moessbauer spectra of NpAl Laves phase alloy obtained. Neptunium was sorbed onto a calcareous deep-sea sediment from sea water, using a successive-loading technique. Sorption appeared to be by an equilibrium reaction, and because of the low solubility of neptunium in seawater, this meant that the maximum loading that could be achieved was 8mg237Np/g sediment. This proved to be an adequate concentration for Moessbauer measurements and a Moessbauer spectrum was obtained. This showed that most of the neptunium was in exchange sites and not present as precipitates of neptunium compounds. It was probably in the 4+ state indicating that reduction had occurred during sorption. This work has demonstrated that Moessbauer Spectroscopy has great potential as an aid to understanding the mechanism of actinide sorption in natural systems. (author)

  10. Effect of the impurity on the results of the fission rate measurements and elimination method

    The nuclear fission method is an important method for neutron measurement. The 235U and 239Pu fission chamber can be used to measure the thermal neutron, and 238U, 232Th and 237Np fission chamber are often used to measure fast neutron. Because the materials for the fission chambers are got by the isotope separation or artificial method, they can contain a few other impurity atoms. The experimental measurements show that the measurement results for the fast neutron can be obviously affected by the few impurities which can be fissioned by the thermal neutron. The thermal fission can be corrected by the method of the thermal fission correction. It also can be eliminated by using the fast fission chamber with Cd