WorldWideScience

Sample records for actinide nuclei fission

  1. Fission theory and actinide fission data

    Energy Technology Data Exchange (ETDEWEB)

    Michaudon, A.

    1975-06-01

    The understanding of the fission process has made great progress recently, as a result of the calculation of fission barriers, using the Strutinsky prescription. Double-humped shapes were obtained for nuclei in the actinide region. Such shapes could explain, in a coherent manner, many different phenomena: fission isomers, structure in near-threshold fission cross sections, intermediate structure in subthreshold fission cross sections and anisotropy in the emission of the fission fragments. A brief review of fission barrier calculations and relevant experimental data is presented. Calculations of fission cross sections, using double-humped barrier shapes and fission channel properties, as obtained from the data discussed previously, are given for some U and Pu isotopes. The fission channel theory of A. Bohr has greatly influenced the study of low-energy fission. However, recent investigation of the yields of prompt neutrons and γ rays emitted in the resonances of {sup 235}U and {sup 239}Pu, together with the spin determination for many resonances of these two nuclei cannot be explained purely in terms of the Bohr theory. Variation in the prompt neutron and γ-ray yields from resonance to resonance does not seem to be due to such fission channels, as was thought previously, but to the effect of the (n,γf) reaction. The number of prompt fission neutrons and the kinetic energy of the fission fragments are affected by the energy balance and damping or viscosity effects in the last stage of the fission process, from saddle point to scission. These effects are discussed for some nuclei, especially for {sup 240}Pu.

  2. Effects of fissioning nuclei distributions on fragment mass distributions for high energy fission

    Directory of Open Access Journals (Sweden)

    Rossi P C R

    2012-02-01

    Full Text Available We study the effects of fissioning nuclei mass- and energy-distributions on the formation of fragments for fission induced by high energy probes. A Monte Carlo code called CRISP was used for obtaining mass distributions and spectra of the fissioning nuclei for reactions induced by 660 MeV protons on 241Am and on 239Np, by 500 MeV protons on 208Pb, and by Bremsstrahlung photons with end-point energies at 50 MeV and 3500 MeV on 238U. The results show that even at high excitation energies, asymmetric fission may still contribute significantly to the fission cross section of actinide nuclei, while it is the dominante mode in the case of lead. However, more precise data for high energy fission on actinide are necessary in order to allow definite conclusions.

  3. Spectroscopy of heavy fissionable nuclei

    Indian Academy of Sciences (India)

    2015-08-05

    Aug 5, 2015 ... Nuclei in the actinide chain and beyond are prone to fission owing to ... mass nuclei are typically more difficult, because the intensity is .... j15/2 neutron alignments in a region where shell stablization effects are crucial.

  4. Nuclear-charge polarization at scission in fission from moderately excited light-actinide nuclei

    International Nuclear Information System (INIS)

    Nishinaka, Ichiro

    2009-01-01

    Fragment mass yields and the average neutron multiplicity in the proton-induced fission of 232 Th and 238 U were measured by a double time-of-flight method. The most probable charges of secondary fragments were evaluated from the fragment mass yields measured by the double time-of-flight method and the fractional cumulative and independent yields reported in literature. The nuclear-charge polarization of primary fragments at scission was obtained by correcting the most probable charge of secondary fragments for neutron evaporation. The results show that the nuclear-charge polarization at scission is associated with the liquid-drop properties of nuclei and the proton shell effect with Z = 50 of heavy fragments and that it is practically insensitive to mass and excitation energy of the fissioning nucleus in the region of light-actinide nuclei. (author)

  5. Fission dynamics of superheavy nuclei formed in uranium induced reactions

    International Nuclear Information System (INIS)

    Gurjit Kaur; Sandhu, Kirandeep; Sharma, Manoj K.

    2017-01-01

    The compound nuclear system follows symmetric fission if the competing processes such as quasi-elastic, deep inelastic, quasi-fission etc are absent. The contribution of quasi fission events towards the fusion-fission mechanism depends on the entrance channel asymmetry of reaction partners, deformations and orientations of colliding nuclei beside the dependence on energy and angular momentum. Usually the 209 Bi and 208 Pb targets are opted for the production of superheavy nuclei with Z CN =104-113. The nuclei in same mass/charge range can also be synthesized using actinide targets + light projectiles (i.e. asymmetric reaction partners) via hot fusion interactions. These actinide targets are prolate deformed which prefer the compact configurations at above barrier energies, indicating the occurrence of symmetric fission events. Here an attempt is made to address the dynamics of light superheavy system (Z CN =104-106), formed via hot fusion interactions involving actinide targets

  6. Sub-barrier quasifission in heavy element formation reactions with deformed actinide target nuclei

    Science.gov (United States)

    Hinde, D. J.; Jeung, D. Y.; Prasad, E.; Wakhle, A.; Dasgupta, M.; Evers, M.; Luong, D. H.; du Rietz, R.; Simenel, C.; Simpson, E. C.; Williams, E.

    2018-02-01

    Background: The formation of superheavy elements (SHEs) by fusion of two massive nuclei is severely inhibited by the competing quasifission process. Low excitation energies favor SHE survival against fusion-fission competition. In "cold" fusion with spherical target nuclei near 208Pb, SHE yields are largest at beam energies significantly below the average capture barrier. In "hot" fusion with statically deformed actinide nuclei, this is not the case. Here the elongated deformation-aligned configurations in sub-barrier capture reactions inhibits fusion (formation of a compact compound nucleus), instead favoring rapid reseparation through quasifission. Purpose: To determine the probabilities of fast and slow quasifission in reactions with prolate statically deformed actinide nuclei, through measurement and quantitative analysis of the dependence of quasifission characteristics at beam energies spanning the average capture barrier energy. Methods: The Australian National University Heavy Ion Accelerator Facility and CUBE fission spectrometer have been used to measure fission and quasifission mass and angle distributions for reactions with projectiles from C to S, bombarding Th and U target nuclei. Results: Mass-asymmetric quasifission occurring on a fast time scale, associated with collisions with the tips of the prolate actinide nuclei, shows a rapid increase in probability with increasing projectile charge, the transition being centered around projectile atomic number ZP=14 . For mass-symmetric fission events, deviations of angular anisotropies from expectations for fusion fission, indicating a component of slower quasifission, suggest a similar transition, but centered around ZP˜8 . Conclusions: Collisions with the tips of statically deformed prolate actinide nuclei show evidence for two distinct quasifission processes of different time scales. Their probabilities both increase rapidly with the projectile charge. The probability of fusion can be severely

  7. Actinide neutron-induced fission up to 20 MeV

    International Nuclear Information System (INIS)

    Maslov, V.M.

    2001-01-01

    Fission and total level densities modelling along with double-humped fission barrier parameters allow to describe available actinide neutron-induced fission cross section data in the incident neutron energy range of ∼ 10 keV - 20 MeV. Saddle asymmetries relevant to shell correction model calculations influence fission barriers, extracted by cross section data analysis. The inner barrier was assumed axially symmetric in case of U, Np and Pu neutron-deficient nuclei. It is shown that observed irregularities in neutron-induced fission cross section data in the energy range of 0.5-3 MeV could be attributed to the interplay of few-quasiparticle excitations in the level density of fissioning and residual nuclei. Estimates of first-chance fission cross section and secondary neutron spectrum model were validated by 238 U fission, (n,2n) and (n,3n) data description up to 20 MeV. (author)

  8. Actinide neutron-induced fission up to 20 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, V M [Radiation Physics and Chemistry Problems Institute, Minsk-Sosny (Belarus)

    2001-12-15

    Fission and total level densities modelling along with double-humped fission barrier parameters allow to describe available actinide neutron-induced fission cross section data in the incident neutron energy range of {approx} 10 keV - 20 MeV. Saddle asymmetries relevant to shell correction model calculations influence fission barriers, extracted by cross section data analysis. The inner barrier was assumed axially symmetric in case of U, Np and Pu neutron-deficient nuclei. It is shown that observed irregularities in neutron-induced fission cross section data in the energy range of 0.5-3 MeV could be attributed to the interplay of few-quasiparticle excitations in the level density of fissioning and residual nuclei. Estimates of first-chance fission cross section and secondary neutron spectrum model were validated by {sup 238}U fission, (n,2n) and (n,3n) data description up to 20 MeV. (author)

  9. Beta-delayed fission and neutron emission calculations for the actinide cosmochronometers

    International Nuclear Information System (INIS)

    Meyer, B.S.; Howard, W.M.; Mathews, G.J.; Takahashi, K.; Moeller, P.; Leander, G.A.

    1989-01-01

    The Gamow-Teller beta-strength distributions for 19 neutron-rich nuclei, including ten of interest for the production of the actinide cosmochronometers, are computed microscopically with a code that treats nuclear deformation explicitly. The strength distributions are then used to calculate the beta-delayed fission, neutron emission, and gamma deexcitation probabilities for these nuclei. Fission is treated both in the complete damping and WKB approximations for penetrabilities through the nuclear potential-energy surface. The resulting fission probabilities differ by factors of 2 to 3 or more from the results of previous calculations using microscopically computed beta-strength distributions around the region of greatest interest for production of the cosmochronometers. The indications are that a consistent treatment of nuclear deformation, fission barriers, and beta-strength functions is important in the calculation of delayed fission probabilities and the production of the actinide cosmochronometers. Since we show that the results are very sensitive to relatively small changes in model assumptions, large chronometric ages for the Galaxy based upon high beta-delayed fission probabilities derived from an inconsistent set of nuclear data calculations must be considered quite uncertain

  10. RIPL starter file parameter validation for actinide nuclei

    International Nuclear Information System (INIS)

    Maslov, V.M.; Porodzinskij, Yu.V.

    1999-01-01

    Nuclear reaction theory calculations are of particular importance for actinide nuclei data evaluation. Measured data base for 238-U provides a unique possibility to compare calculated data with measured total, elastic, inelastic, fission, capture, (n,2n), (n,3n) and (n,4n) cross section data up to 40 MeV

  11. Status of measurements of fission neutron spectra of Minor Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Drapchinsky, L.; Shiryaev, B. [V.G. Khlopin Radium Inst., Saint Petersburg (Russian Federation)

    1997-03-01

    The report considers experimental and theoretical works on studying the energy spectra of prompt neutrons emitted in spontaneous fission and neutron induced fission of Minor Actinides. It is noted that neutron spectra investigations were done for only a small number of such nuclei, most measurements, except those of Cf-252, having been carried out long ago by obsolete methods and imperfectapparatus. The works have no detailed description of experiments, analysis of errors, detailed numerical information about results of experiments. A conclusion is made that the available data do not come up to modern requirements. It is necessary to make new measurements of fission prompt neutron spectra of transuranium nuclides important for the objectives of working out a conception of minor actinides transmutation by means of special reactors. (author)

  12. Systematic features of mass yield curves in low-energy fission of actinides

    International Nuclear Information System (INIS)

    Nagame, Yuichiro

    1999-01-01

    Characteristics of mass yield curves in fission of wide range of nuclides from pre-actinides through transactinides are reviewed and the following points are discussed. (1) Systematic trends of the mass yield distributions in low-energy proton-induced fission of actinides and in spontaneous fission of actinides are discussed in terms of weighted mean mass numbers of the light and heavy asymmetric mass yield peaks and widths of the heavy asymmetric mass yields. (2) Gross features of the two kinds of mass yield curves, symmetric and asymmetric ones, as a function of a fissioning nucleus. (3) Competition between the symmetric and asymmetric fission as a function of not only Z (proton number) but also N (neutron number) of a fissioning nucleus. (4) Experimental verification of the existence of two kinds of deformation paths in low energy fission of actinides; the first path is initiated at higher threshold energy and ends with elongated scission configuration, giving a final mass yield distribution centered around the symmetric mass division, 'symmetric fission path'. In the second path, a fissioning nucleus experiences lower threshold energy and results in more compact scission configuration, which gives a double humped mass distribution always centered around A=140 for the heavier fragment, 'asymmetric fission path'. (5) Interpretation of the 'bimodal fission' observed in the spontaneous fission of heavy actinides as the presence of the two fission paths of the ordinary asymmetric one and a strongly shell-affected symmetric path from the systematic analysis of scission configurations. (6) A dynamical fission process deduced from the analysis of the experimental mass yield curves and the correlation data of neutron multiplicity and fragment mass and total kinetic energy. (7) Prediction of the characteristics of gross properties of fission in superheavy nuclei around 280 114. (8) Characteristics of highly asymmetric fission: formation cross section as a function of

  13. Measurements of actinide-fission product yields in Caliban and Prospero metallic core reactor fission neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Casoli, P.; Authier, N. [CEA, Centre de Valduc, 21120 Is-sur-Tille (France); Laurec, J.; Bauge, E.; Granier, T. [CEA, Centre DIF, 91297 Arpajon (France)

    2011-07-01

    In the 1970's and early 1980's, an experimental program was performed on the facilities of the CEA Valduc Research Center to measure several actinide-fission product yields. Experiments were, in particular, completed on the Caliban and Prospero metallic core reactors to study fission-neutron-induced reactions on {sup 233}U, {sup 235}U, and {sup 239}Pu. Thick actinide samples were irradiated and the number of nuclei of each fission product was determined by gamma spectrometry. Fission chambers were irradiated simultaneously to measure the numbers of fissions in thin deposits of the same actinides. The masses of the thick samples and the thin deposits were determined by mass spectrometry and alpha spectrometry. The results of these experiments will be fully presented in this paper for the first time. A description of the Caliban and Prospero reactors, their characteristics and performances, and explanations about the experimental approach will also be given in the article. A recent work has been completed to analyze and reinterpret these measurements and particularly to evaluate the associated uncertainties. In this context, calculations have also been carried out with the Monte Carlo transport code Tripoli-4, using the published benchmarked Caliban description and a three-dimensional model of Prospero, to determine the average neutron energy causing fission. Simulation results will be discussed in this paper. Finally, new fission yield measurements will be proposed on Caliban and Prospero reactors to strengthen the results of the first experiments. (authors)

  14. $\\beta$-delayed fission in proton-rich nuclei in the lead region

    CERN Document Server

    AUTHOR|(CDS)2085005; Huyse, Mark; Popescu, Lucia

    Nuclear fission is the breakup of an atomic nucleus into two (sometimes three) fragments, thereby releasing a large amount of energy. Soon after its discovery in the late 1930’s, the gross properties of the fission phenomenon were explained by macroscopic nuclear models. Certain features however, such as asymmetric fission-fragment mass distributions in the actinide region, require the inclusion of microscopic effects. This interplay of the microscopic motion of individual nucleons on this macroscopic process is, until today, not yet fully understood. The phenomenon of fission has therefore been of recurring interest for both theoretical and experimental studies. This thesis work focuses on the $\\beta$-delayed fission ($\\beta$DF) process, an excellent tool to study low-energy fission of exotic nuclei, which was discovered in 1966 in the actinide region. In this two-step process, a precursor nucleus first undergoes $\\beta$-decay to an excited level in the daughter nucleus, which may subsequently fission. Rec...

  15. Study of actinides fission induced by multi-nucleon transfer reactions in inverse kinematics

    International Nuclear Information System (INIS)

    Derkx, X.

    2010-10-01

    The study of actinide fission encounters two major issues. On one hand, measurements of the fission fragment distributions and the fission probabilities allow a better understanding of the fission process itself and the discrimination among the models of nuclear structure and dynamics. On the other hand, new measurements are required to improve nuclear data bases, which are a key component for the design of new generation reactors and radio-toxic waste incinerators. This thesis is in line with different French and American experimental projects using the surrogate method, i.e. transfer reactions leading to the same compound nuclei as in neutron irradiation, allowing the study of fission of actinides which are inaccessible by conventional techniques, whereas they are important for applications. The experiment is based on multi-nucleon transfer reactions between a 238 U beam and a 12 C target, using the inverse kinematics technique to measure, for each transfer channel, the complete isotopic distributions of the fission fragments with the VAMOS spectrometer. The work presented in this dissertation is focused on the identification of the transfer channels and their properties, as their angular distributions and the distributions of the associated excitation energy, using the SPIDER telescope to identify the target recoil nuclei. This work of an exploratory nature aims to generalize the surrogate method to heavy transfers and to measure, for the first time, the fission probabilities in inverse kinematics. The obtained results are compared with available direct kinematics and neutron irradiation measurements. (author)

  16. Chemistry of actinides and fission products

    International Nuclear Information System (INIS)

    Pruett, D.J.; Sherrow, S.A.; Toth, L.M.

    1988-01-01

    This task is concerned primarily with the fundamental chemistry of the actinide and fission product elements. Special efforts are made to develop research programs in collaboration with researchers at universities and in industry who have need of national laboratory facilities. Specific areas currently under investigation include: (1) spectroscopy and photochemistry of actinides in low-temperature matrices; (2) small-angle scattering studies of hydrous actinide and fission product polymers in aqueous and nonaqueous solvents; (3) kinetic and thermodynamic studies of complexation reactions in aqueous and nonaqueous solutions; and (4) the development of inorganic ion exchange materials for actinide and lanthanide separations. Recent results from work in these areas are summarized here

  17. Fission properties of odd-A nuclei in a mean field framework

    International Nuclear Information System (INIS)

    Perez-Martin, S.; Robledo, L.M.

    2009-01-01

    Theoretical tools at the level of the mean field approximation are used to explore the spontaneous fission properties of odd-A nuclei. The tools rely on the equal (or uniform) filling approximation to deal with the unpaired nucleon in a time-reversal preserving manner. Realistic calculations have been carried out with the finite range Gogny force D1S, which was tailored to reasonably reproduce fission properties in the actinides. The preliminary results obtained for the nucleus 235 U are analyzed and the physical origin for the hindrance factor for the spontaneous fission half life is discussed. (author)

  18. Possible existence of backbending in actinide nuclei

    International Nuclear Information System (INIS)

    Dudek, J.; Nazarewicz, W.; Szymanski, Z.

    1982-01-01

    The possibilities for the backbending effect to occur in actinide nuclei are studied using the pairing-self-consistent independent quasiparticle method. The Hamiltonian used is that of the deformed Woods-Saxon potential plus monopole pairing term. The results of the calculations explain why there is no backbending in most actinide nuclei and simultaneously suggest that in some light neutron deficient nuclei around Th and 22 Ra a backbending effect may occur

  19. Fission barriers of two odd-neutron heavy nuclei

    International Nuclear Information System (INIS)

    Koh, Meng-Hock; Bonneau, L.; Nhan Hao, T. V.; Duc, Dao Duy; Quentin, P.

    2015-01-01

    The fission barriers of two odd-neutron heavy odd nuclei,namely the 235 U and 239 Pu isotopes have been calculated within a self-consistent Hartree-Fock-plus-BCS approach with blocking. A Skyrme nucleon-nucleon effective interaction has been used together with a seniority force to describe pairing correlations. A full account of the genuine time-reversal symmetry breaking due to the presence of an unpaired nucleon has been incorporated at the mean field level. The SIII and SkM* parametrizations of the Skyrme interaction have been retained as well as for a part a newer parametrization, SLy5*. The seniority force parameters have been fitted to reproduce experimental odd-even mass differences in the actinide region. To assess the relevance of our calculated fission barrier distribution (as a function of the quantum numbers), we have studied the quality of our results with respect to the spectroscopy of band heads (for configurations deemed to be a pure single particle character) in the ground and fission isomeric states. Fission barriers of the considered odd nuclei have been compared with what is obtained for their even-even neighbouring isotopes (namely 234 U and 236 U, 238 Pu and 240 Pu respectively) to determine the so-called specialization energies. Various corrections and associated uncertainties have been discussed in order to compare our results with available data

  20. Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS

    International Nuclear Information System (INIS)

    Perkasa, Y. S.; Waris, A.; Kurniadi, R.; Su'ud, Z.

    2014-01-01

    Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS have been conducted. In this work, fission cross section resulted from MCNP6 prediction will be compared with result from TALYS calculation. MCNP6 with its event generator CEM03.03 and LAQGSM03.03 have been validated and verified for several intermediate and heavy nuclides fission reaction data and also has a good agreement with experimental data for fission reaction that induced by photons, pions, and nucleons at energy from several ten of MeV to about 1 TeV. The calculation that induced within TALYS will be focused mainly to several hundred MeV for actinide and sub-actinide nuclides and will be compared with MCNP6 code and several experimental data from other evaluator

  1. Non-compound nucleus fission in actinide and pre-actinide regions

    Indian Academy of Sciences (India)

    Data on the evaporation residue cross-sections, in addition to those on mass and angular distributions, are necessary for better understanding of the contribution from non-compound nucleus fission in the pre-actinide region. Measurement of mass-resolved angular distribution of fission products in 20Ne+232Th reaction ...

  2. Strength of Coriolis Coupling in actinide nuclei

    International Nuclear Information System (INIS)

    Peker, L.K.; Rasmussen, J.O.; Hamilton, J.H.

    1982-01-01

    Coriolis Coupling V/sub cor/ plays an important role in deformed nuclei. V/sub cor/ is proportional to h 2 /J[j (j + 1) -Ω (Ω + 1)]/sup 1/2/ and therefore is particularly significant in the nuclei with large j and low Ω Nilsson levels close to Fermi surface: n(i/sub 13/2/) in A = 150 to 170 rare-earth nuclei and p(i/sub 13/2/) and n(j/sub 15/2/) in A greater than or equal to 224 actinide nuclei. Because of larger j (n(j/sub 15/2/) versus n(i/sub 13/2/)) and smaller deformations (β approx. = 0.22 versus β 0.28) it was reasonable to expect that in actinide nuclei Coriolis effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed Coriolis effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis ad pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction V/sub eff/ of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda F). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction V/sub eff/ is strong, and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei

  3. Actinide and fission product separation and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-07-01

    The second international information exchange meeting on actinide and fission product separation and transmutation, took place in Argonne National Laboratory in Illinois United States, on 11-13 November 1992. The proceedings are presented in four sessions: Current strategic system of actinide and fission product separation and transmutation, progress in R and D on partitioning processes wet and dry, progress in R and D on transmutation and refinements of neutronic and other data, development of the fuel cycle processes fuel types and targets. (A.L.B.)

  4. Application of dynamic pseudo fission products and actinides for accurate burnup calculations

    Energy Technology Data Exchange (ETDEWEB)

    Hoogenboom, J.E.; Leege, P.F.A. de [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.; Kloosterman, J.L.

    1996-09-01

    The introduction of pseudo fission products for accurate fine-group spectrum calculations during burnup is discussed. The calculation of the density of the pseudo nuclides is done before each spectrum calculation from the actual densities and their cross sections of all nuclides to be lumped into a pseudo fission product. As there are also many actinides formed in the fuel during its life cycle, a pseudo actinide with fission cross section is also introduced. From a realistic burnup calculation it is demonstrated that only a few fission products and actinides need to be included explicitly in a spectrum calculation. All other fission products and actinides can be accurately represented in the pseudo nuclides. (author)

  5. Theoretical Description of the Fission Process

    International Nuclear Information System (INIS)

    Witold Nazarewicz

    2003-01-01

    The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process

  6. Theoretical Description of the Fission Process

    Energy Technology Data Exchange (ETDEWEB)

    Witold Nazarewicz

    2003-07-01

    The main goals of the project can be summarized as follows: Development of effective energy functionals that are appropriate for the description of heavy nuclei. Our goal is to improve the existing energy density (Skyrme) functionals to develop a force that will be used in calculations of fission dynamics. Systematic self-consistent calculations of binding energies and fission barriers of actinide and trans-actinide nuclei using modern density functionals. This will be followed by calculations of spontaneous fission lifetimes and mass and charge divisions using dynamic adiabatic approaches based on the WKB approximation. Investigate novel microscopic (non-adiabatic) methods to study the fission process.

  7. Status report on actinide and fission product transmutation studies

    International Nuclear Information System (INIS)

    1997-06-01

    The management of radioactive waste is one of the key issues in today's political and public discussions on nuclear energy. One of the fields that looks into the future possibilities of nuclear technology is the neutronic transmutation of actinides and of some most important fission products. Studies on transmutation of actinides are carried out in various countries and at an international level. This status report which gives an up-to-date general overview of current and planned research on transmutation of actinides and fission products in non-OECD countries, has been prepared by a Technical Committee meeting organized by the IAEA in September 1995. 168 refs, 16 figs, 34 tabs

  8. Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O+232Th reaction

    Directory of Open Access Journals (Sweden)

    R. Léguillon

    2016-10-01

    Full Text Available It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O+232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model.

  9. Nuclear fission and neutron-induced fission cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    James, G.D.; Lynn, J.E.; Michaudon, A.; Rowlands, J.; de Saussure, G.

    1981-01-01

    A general presentation of current knowledge of the fission process is given with emphasis on the low energy fission of actinide nuclei and neutron induced fission. The need for and the required accuracy of fission cross section data in nuclear energy programs are discussed. A summary is given of the steps involved in fission cross section measurement and the range of available techniques. Methods of fission detection are described with emphasis on energy dependent changed and detector efficiency. Examples of cross section measurements are given and data reduction is discussed. The calculation of fission cross sections is discussed and relevant nuclear theory including the formation and decay of compound nuclei and energy level density is introduced. A description of a practical computation of fission cross sections is given.

  10. Static and dynamic deformations of actinide nuclei

    International Nuclear Information System (INIS)

    Rozmej, P.

    1985-09-01

    The zero-point quadrupole-hexadecapole vibrations have been taken into account to calculate dynamical deformations for even-even actinide nuclei. The collective and intrinsic motions are separated according to the Born-Oppenheimer approximation. The collective Hamiltonian is constructed using the macroscopic-microscopic method in the potential energy part and the cranking model in the kinetic energy part. The BCS theory with a modified oscillator potential is applied to describe the intrinsic motion of nucleons. A new set of Nilsson potential parameters, which produces a much better description of the properties of light actinide nuclei, has also been found. (orig.)

  11. Fission cross section measurements for minor actinides

    Energy Technology Data Exchange (ETDEWEB)

    Fursov, B. [IPPE, Obninsk (Russian Federation)

    1997-03-01

    The main task of this work is the measurement of fast neutron induced fission cross section for minor actinides of {sup 238}Pu, {sup 242m}Am, {sup 243,244,245,246,247,248}Cm. The task of the work is to increase the accuracy of data in MeV energy region. Basic experimental method, fissile samples, fission detectors and electronics, track detectors, alpha counting, neutron generation, fission rate measurement, corrections to the data and error analysis are presented in this paper. (author)

  12. Fast neutron scattering on actinide nuclei

    International Nuclear Information System (INIS)

    1982-01-01

    More and more sophisticated neutron experiments have been carried out with better samples in several laboratories and it was necessary to intercompare them. In this respect, let us quote for example (n,n'e) and (n,n'#betta#) measurements. Moreover, high precision (p,p), (p,p') and (p,n) measurements have been made, thus supplementing neutron experiments in the determination of the parameters of the optical model, still widely used to describe the neutron-nucleus interaction. The optical model plays a major role and it is therefore essential to know it well. The spherical optical model is still very useful, especially because of its simplicity and of the relatively short calculation times, but is obviously insufficient to treat deformed nuclei such as actinides. For accurate calculations about these nuclei, it is necessary to use a deformed potential well and solve a set of coupled equations, hence long computational times. The importance of compound nucleus formation at low energy requires also a good knowledge of the statistical model together with that of all the reaction mechanisms which are involved, including fission for which an accurate barrier is necessary and, of course, well-adjusted level densities. The considerations form the background of the Scientific Programme set up by a Programme Committee whose composition is given further on in this book

  13. Fission properties of very heavy actinides

    International Nuclear Information System (INIS)

    Hoffman, D.C.

    1979-01-01

    The existing data on neutron-emission, kinetic-energy and mass distributions, and half-lives for spontaneous fission of the heavy actinides are reviewed. A comparison of the data for the Fm isotopes with heavier and lighter nuclides suggests that the properties of the heavy Fm isotopes may be unique and can qualitatively be explained on the basis of fragment shell effects, i.e., symmetric fission results in two fragments with configurations close to the doubly magic 132 Sn nucleus. The effect of excitation energy and the use of systematics and theoretical predictions of fission properties and half-lives in the identification of new heavy element isotopes is discussed. 54 references

  14. Influence of a diffuse distribution of nucleon density on the effective moments of inertia of fissioning nuclei

    International Nuclear Information System (INIS)

    Adeev, G.; Trunova, T.

    1982-01-01

    The effective moments of inertia of pre-actinide nuclei with 73< or =Z< or =85 are calculated in the droplet model. In contrast to studies carried out previously, the influence of the diffuseness of the nuclear surface and the nonuniformity of the distribution of nucleon density was taken into account both in calculation of the saddle-point configurations and directly in calculation of the effective moments of inertia of the fissioning nuclei. The results are compared with the moments of inertia calculated in the liquid-drop model and with experimental data

  15. Alpha decay and cluster decay of some neutron-rich actinide nuclei

    Indian Academy of Sciences (India)

    2017-02-09

    Feb 9, 2017 ... Abstract. Nuclei in the actinide region are good in exhibiting cluster radioactivity. In the present work, the half-lives of α-decay and heavy cluster emission from certain actinide nuclei have been calculated using cubic plus Yukawa plus exponential model (CYEM). Our model has a cubic potential for the ...

  16. Studies on the properties of hard-spectrum, actinide fissioning reactors. Final report

    International Nuclear Information System (INIS)

    Nelson, J.B.; Prichard, A.W.; Schofield, P.E.; Robinson, A.H.; Spinrad, B.I.

    1980-01-01

    It is technically feasible to construct an operable (e.g., safe and stable) reactor to burn waste actinides rapidly. The heart of the concept is a driver core of EBR-II type, with a central radial target zone in which fuel elements, made entirely of waste actinides are exposed. This target fuel undergoes fission, as a result of which actinides are rapidly destroyed. Although the same result could be achieved in more conventionally designed LWR or LMFBR systems, the fast spectrum reactor does a much more efficient job, by virtue of the fact that in both LWR and LMFBR reactors, actinide fission is preceded by several captures before a fissile nuclide is formed. In the fast spectrum reactor that is called ABR (actinide burning reactor), these neutron captures are short-circuited

  17. Actinides and fission products partitioning from high level liquid waste

    International Nuclear Information System (INIS)

    Yamaura, Mitiko

    1999-01-01

    The presence of small amount of mixed actinides and long-lived heat generators fission products as 137 Cs and 90 Sr are the major problems for safety handling and disposal of high level nuclear wastes. In this work, actinides and fission products partitioning process, as an alternative process for waste treatment is proposed. First of all, ammonium phosphotungstate (PWA), a selective inorganic exchanger for cesium separation was chosen and a new procedure for synthesizing PWA into the organic resin was developed. An strong anionic resin loaded with tungstate or phosphotungstate anion enables the precipitation of PWA directly in the resinous structure by adding the ammonium nitrate in acid medium (R-PWA). Parameters as W/P ratio, pH, reactants, temperature and aging were studied. The R-PWA obtained by using phosphotungstate solution prepared with W/P=9.6, 9 hours digestion time at 94-106 deg C and 4 to 5 months aging time showed the best capacity for cesium retention. On the other hand, Sr separation was performed by technique of extraction chromatography, using DH18C6 impregnated on XAD7 resin as stationary phase. Sr is selectively extracted from acid solution and >99% was recovered from loaded column using distilled water as eluent. Concerning to actinides separations, two extraction chromatographic columns were used. In the first one, TBP(XAD7) column, U and Pu were extracted and its separations were carried-out using HNO 3 and hydroxylamine nitrate + HNO 3 as eluent. In the second one, CMP0-TBP(XAD7) column, the actinides were retained on the column and the separations were done by using (NH 4 ) 2 C 2 O 4 , DTPA, HNO 3 and HCl as eluent. The behavior of some fission products were also verified in both columns. Based on the obtained data, actinides and fission products Cs and Sr partitioning process, using TBP(XAD7) and CMP0-TBP(XAD7) columns for actinides separation, R-PWA column for cesium retention and DH18C6(XAD7) column for Sr isolation was performed

  18. Isotopic resolution of fission fragments from 238U + 12C transfer and fusion reactions

    International Nuclear Information System (INIS)

    Caamano, M.; Rejmund, F.; Derkx, X.; Schmidt, K. H.; Andouin, L.; Bacri, C. O.; Barreau, G.; Benlliure, J.; Casarejos, E.; Fernandez-Dominguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Navin, A.; Rejmund, M.; Roger, T.; Shrivastava, A.; Schmitt, C.; Taieb, J.

    2010-01-01

    Recent results from an experiment at GANIL, performed to investigate the main properties of fission-fragment yields and energy distributions in different fissioning nuclei as a function of the excitation energy, in a neutron-rich region of actinides, are presented. Transfer reactions in inverse kinematics between a 238 U beam and a 12 C target produced different actinides, within a range of excitation energy below 30 MeV. These fissioning nuclei are identified by detecting the target-like recoil, and their kinetic and excitation energy are determined from the reconstruction of the transfer reaction. The large-acceptance spectrometer VAMOS was used to identify the mass, atomic number and charge state of the fission fragments in flight. As a result, the characteristics of the fission-fragment isotopic distributions of a variety of neutron-rich actinides are observed for the first time over the complete range of fission fragments. (authors)

  19. Transmutation of fission products and actinide waste at Hanford

    Energy Technology Data Exchange (ETDEWEB)

    Daemen, L.L.; Pitcher, E.J.; Russell, G.J. [Los Alamos National Laboratory, NM (United States)

    1995-10-01

    The authors studied the neutronics of an ATW system for the transmutation of the fission products ({sup 99}Tc in particular) and the type of actinide waste stored in several tanks at Hanford. The heart of the system is a highly-efficient neutron production target. It is surrounded by a blanket containing a moderator/reflector material, as well as the products to be transmuted. The fission products are injected into the blanket in the form of an aqueous solution in heavy water, whereas an aqueous actinides slurry is circulated in the outer part of the blanket. For the sake of definiteness, the authors focussed on {sup 99}Tc (the most difficult fission product to transmute), and {sup 239}Pu, {sup 237}Np, and {sup 241}Am. Because of the low thermal neutron absorption cross-section of {sup 99}Tc, considerable care and effort must be devoted to the design of a very efficient neutron source.

  20. High flux transmutation of fission products and actinides

    International Nuclear Information System (INIS)

    Gerasimov, A.; Kiselev, G.; Myrtsymova, L.

    2001-01-01

    Long-lived fission products and minor actinides accumulated in spent nuclear fuel of power reactors comprise the major part of high level radwaste. Their incineration is important from the point of view of radwaste management. Transmutation of these nuclides by means of neutron irradiation can be performed either in conventional nuclear reactors, or in specialized transmutation reactors, or in ADS facilities with subcritical reactor and neutron source with application of proton accelerator. Different types of transmutation nuclear facilities can be used in order to insure optimal incineration conditions for radwaste. The choice of facility type for optimal transmutation should be based on the fundamental data in the physics of nuclide transformations. Transmutation of minor actinides leads to the increase of radiotoxicity during irradiation. It takes significant time compared to the lifetime of reactor facility to achieve equilibrium without effective transmutation. High flux nuclear facilities allow to minimize these draw-backs of conventional facilities with both thermal and fast neutron spectrum. They provide fast approach to equilibrium and low level of equilibrium mass and radiotoxicity of transmuted actinides. High flux facilities are advantageous also for transmutation of long-lived fission products as they provide short incineration time

  1. Actinide and fission product partitioning and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-01

    The third international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Cadarache France, on 12-14 December 1994. The proceedings are presented in six sessions : an introduction session, the major programmes and international cooperation, the systems studies, the reactors fuels and targets, the chemistry and a last discussions session. (A.L.B.)

  2. US/UK actinides experiment at the Dounreay PFR. I. Fission products

    International Nuclear Information System (INIS)

    Raman, S.; Murphy, B.D.

    1995-01-01

    The United States and the United Kingdom have been engaged in a joint research program in which samples of higher actinides were irradiated in the 600-MW Dounreay Prototype Fast Reactor in Scotland. Analytical results using mass spectrometry and radiometry for actinides and fission products are now available for the samples in Fuel Pins 1 and 2 which were irradiated for 63 full-power days and for the samples in Fuel Pin 4 which were irradiated for 492 full-power days. Results from these three fuel pins are providing estimates of integral cross sections and fission yields. (authors)

  3. Fission barriers of light nuclei

    International Nuclear Information System (INIS)

    Grotowski, K.; Planeta, R.; Blann, M.; Komoto, T.

    1989-01-01

    Experimental fission excitation functions for compound nuclei /sup 52/Fe, /sup 49/Cr, /sup 46/V, and /sup 44/Ti formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems

  4. Measurement of fast neutron induced fission cross section of minor-actinide

    International Nuclear Information System (INIS)

    Hirakawa, Naohiro

    2000-06-01

    In fuel cycles with recycled actinide, core characteristics are largely influenced by minor actinide (MA: Np, Am, Cm). Accurate nuclear data of MA such as fission cross section are required to estimate the effect of MA with high accuracy. In this study, fast neutron induced fission cross section of MA is measured using Dynamitron accelerator in Tohoku University. The followings were performed in this fiscal year; (1) Research of nuclear data of MA, (2) Sample preparation and sample mass assay, (3) Investigation of neutron sources with the energy of several 10 keV, (4) Preliminary measurement of fission cross section using Dynamitron accelerator. As the result, four 237 Np samples were prepared and the sample mass were measured using alpha-spectrometry with the accuracy of 1.2%. Then, it was confirmed that a neutron source via 7 Li(p,n) 7 Be reaction using a Li-thick target is suitable for measuring fission cross section of MA in the energy region of several 10 keV. Furthermore, it was verified by the preliminary measurement that the measurement of fission cross section of MA is available using a fission chamber and electronics developed in this study. (author)

  5. Bimodal nature in low-energy fission of light actinides

    International Nuclear Information System (INIS)

    Nagame, Yuichiro; Nishinaka, Ichiro; Tsukada, Kazuaki; Ikezoe, Hiroshi; Otsuki, Tsutomu; Sueki, Keisuke; Nakahara, Hiromichi; Kudo, Hisaaki.

    1995-01-01

    To solve various problems in the mass division process of light actinoids, some experiments on the basis of bimodal fission were carried. Mass and kinetic energy distribution of Th-232 and U-238 were determined. Pa-225 (N= 134) and Pa-227 (N=136), fission nuclei, were produced by Bi-209 + 0-16 and Bi-209 + 0-18 heavy ion nucleus reactions, and the mass yield distribution were determined by the time-of-flight method and the radiochemical procedure. From the results, two independent deforming processes were proved in the fission process of light actinoid nuclei. On the deforming process through the low fission barrier, nucleus fissioned after small deformation under the influence of stabilization of the shell structure of fission product. In the case of process through the high barrier, however, the nucleus fissioned after large deformation. The unsymmetrical mass division was derived from the former and the symmetrical one from the latter. (S.Y.)

  6. Consultants' meeting on prompt fission neutron spectra of major actinides. Summary report

    International Nuclear Information System (INIS)

    Capote Noy, R.; Maslov, V.; Bauge, E.; Ohsawa, T.; Vorobyev, A.; Chadwick, M.B.; Oberstedt, S.

    2009-01-01

    A Consultants' Meeting on 'Prompt Fission Neutron Spectra of Major Actinides' was held at IAEA Headquarters, Vienna, Austria, to discuss the adequacy and quality of the recommended prompt fission neutron spectra to be found in existing nuclear data applications libraries. These prompt fission neutron spectra were judged to be inadequate, and this problem has proved difficult to resolve by means of theoretical modelling. Major adjustments may be required to ensure the validity of such important data. There is a strong requirement for an international effort to explore and resolve these difficulties and recommend prompt fission neutron spectra and uncertainty covariance matrices for the actinides over the neutron energy range from thermal to 20 MeV. Participants also stressed that there would be a strong need for validation of the resulting data against integral critical assembly and dosimetry data. (author)

  7. Actinide and fission product partitioning and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-01

    The fourth international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Mito City in Japan, on 111-13 September 1996. The proceedings are presented in six sessions: the major programmes and international cooperation, the partitioning and transmutation programs, feasibility studies, particular separation processes, the accelerator driven transmutation, and the chemistry of the fuel cycle. (A.L.B.)

  8. Fission of nuclei far from stability

    International Nuclear Information System (INIS)

    Schmidt, K.H.; Benlliure, J.; Junghans, A.R.

    2000-11-01

    The secondary-beam facility of GSI provided the technical equipment for a new kind of fission experiment. Fission properties of short-lived neutron-deficient nuclei have been investigated in inverse kinematics. The measured element distributions reveal new kinds of systematics on shell structure and even-odd effects and lead to an improved understanding of structure effects in nuclear fission. Prospects for further experimental studies are discussed. (orig.)

  9. Fission cross section measurements at intermediate energies

    International Nuclear Information System (INIS)

    Laptev, Alexander

    2005-01-01

    The activity in intermediate energy particle induced fission cross-section measurements of Pu, U isotopes, minor actinides and sub-actinides in PNPI of Russia is reviewed. The neutron-induced fission cross-section measurements are under way in the wide energy range of incident neutrons from 0.5 MeV to 200 MeV at the GNEIS facility. In number of experiments at the GNEIS facility, the neutron-induced fission cross sections were obtained for many nuclei. In another group of experiments the proton-induced fission cross-section have been measured for proton energies ranging from 200 to 1000 MeV at 100 MeV intervals using the proton beam of PNPI synchrocyclotron. (author)

  10. Studies of Fission-Induced Surface Damage in Actinides Using Ultracold Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Broussard, Leah J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-05

    This report describes the results of the fission-induced actinide studies at LANL. Previously, there was no fission data at these energies though there were initial characterizations of UCN energy dependence and material thickness. The proof of principle was demonstrated and the initial characterizations of sputtered rates, angular and size distribution are underway.

  11. Basic physics of the fission process. Chapter 2

    International Nuclear Information System (INIS)

    Michaudon, A.

    1981-01-01

    A general description of the fission process is given with special emphasis on those aspects which are necessary for the understanding of the measurements and calculations of neutron-induced fission cross-sections. Having considered the various phases of the process, some typical properties of the low-energy fission of actinide nuclei are presented and the more specific features of neutron induced fission are examined. (U.K.)

  12. Measurement of fast neutron induced fission cross section of minor-actinide

    International Nuclear Information System (INIS)

    Hirakawa, Naohiro

    1997-03-01

    In fuel cycles with recycled actinide, core characteristics are largely influenced by minor actinide (MA: Np, Am, Cm). Accurate nuclear data of MA such as fission cross section are required to estimate the effect of MA with high accuracy. In this study, fast neutron induced fission cross section of MA is measured using Dynamitron Accelerator in Tohoku University. The experimental method and the samples, which were developed or introduced during the last year, were improved in this fiscal year: (1) Development of a sealed fission chamber, (2) Intensification of Li neutron target, (3) Improvement of time-resolution of Time-of-Flight (TOF) electronic circuit, (4) Introduction of Np237 samples with large sample mass and (5) Introduction of a U235 sample with high purity. Using these improved tools and samples, the fission cross section ratio of Np237 relative to U235 was measured between 5 to 100 keV, and the fission cross section of Np237 was deduced. On the other hand, samples of Am241 and Am243 were obtained from Japan Atomic Energy Research Institute (JAERI) after investigating fission cross section of two americium isotopes (Am241 and Am 243) which are important for core physics calculation of fast reactors. (author)

  13. Properties of Fission-Product decay heat from Minor-Actinide fissioning systems

    International Nuclear Information System (INIS)

    Oyamatsu, Kazuhiro; Mori, Hideki

    2000-01-01

    The aggregate Fission-Product (FP) decay heat after a pulse fission is examined for Minor Actinide (MA) fissiles 237 Np, 241 Am, 243 Am, 242 Cm and 244 Cm. We find that the MA decay heat is comparable but smaller than that of 235 U except for cooling times at about 10 8 s (approx. = 3 y). At these cooling times, either the β or γ component of the FP decay heat for these MA's is substantially larger than the one for 235 U. This difference is found to originate from the cumulative fission yield of 106 Ru (T 1/2 = 3.2x10 7 s). This nuclide is the parent of 106 Rh (T 1/2 = 29.8 s) which is the dominant source of the decay heat at 10 8 s (approx. = 3 y). The fission yield is nearly an increasing function of the fissile mass number so that the FP decay heat is the largest for 244 Cm among the MA's at the cooling time. (author)

  14. Fission cross section measurements of actinides at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Tovesson, Fredrik [Los Alamos National Laboratory; Laptev, Alexander B [Los Alamos National Laboratory; Hill, Tony S [INL

    2010-01-01

    Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the {sup 235}U standard. Recent measurements include the {sup 233,238}U, {sup 239,242}Pu and {sup 243}Am neutron-induced fission cross sections. In this paper preliminary results for cross section data of {sup 243}Am and {sup 233}U will be presented.

  15. Seventy-five years of nuclear fission

    Indian Academy of Sciences (India)

    technology can play such a vital role in a nation's development subsequently motivated ... fragments with a broad mass distribution is a unique nuclear phenomenon ... low energy and spontaneous fission of actinide nuclei and how these ...

  16. Actinide neutron-induced fission cross section measurements at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Tovesson, Fredrik K [Los Alamos National Laboratory; Laptev, Alexander B [Los Alamos National Laboratory; Hill, Tony S [INL

    2010-01-01

    Fission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications in a wide energy range from sub-thermal energies up to 200 MeV. A parallel-plate ionization chamber are used to measure fission cross sections ratios relative to the {sup 235}U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the {sup 233,238}U, {sup 239-242}Pu and {sup 243}Am neutron-induced fission cross sections. Obtained data are presented in comparison with ex isting evaluations and previous data.

  17. A comparison of radioactive waste from first generation fusion reactors and fast fission reactors with actinide recycling

    International Nuclear Information System (INIS)

    Koch, M.; Kazimi, M.S.

    1991-04-01

    Limitations of the fission fuel resources will presumably mandate the replacement of thermal fission reactors by fast fission reactors that operate on a self-sufficient closed fuel cycle. This replacement might take place within the next one hundred years, so the direct competitors of fusion reactors will be fission reactors of the latter rather than the former type. Also, fast fission reactors, in contrast to thermal fission reactors, have the potential for transmuting long-lived actinides into short-lived fission products. The associated reduction of the long-term activation of radioactive waste due to actinides makes the comparison of radioactive waste from fast fission reactors to that from fusion reactors more rewarding than the comparison of radioactive waste from thermal fission reactors to that from fusion reactors. Radioactive waste from an experimental and a commercial fast fission reactor and an experimental and a commercial fusion reactor has been characterized. The fast fission reactors chosen for this study were the Experimental Breeder Reactor 2 and the Integral Fast Reactor. The fusion reactors chosen for this study were the International Thermonuclear Experimental Reactor and a Reduced Activation Ferrite Helium Tokamak. The comparison of radioactive waste parameters shows that radioactive waste from the experimental fast fission reactor may be less hazardous than that from the experimental fusion reactor. Inclusion of the actinides would reverse this conclusion only in the long-term. Radioactive waste from the commercial fusion reactor may always be less hazardous than that from the commercial fast fission reactor, irrespective of the inclusion or exclusion of the actinides. The fusion waste would even be far less hazardous, if advanced structural materials, like silicon carbide or vanadium alloy, were employed

  18. A comparison of radioactive waste from first generation fusion reactors and fast fission reactors with actinide recycling

    Energy Technology Data Exchange (ETDEWEB)

    Koch, M.; Kazimi, M.S.

    1991-04-01

    Limitations of the fission fuel resources will presumably mandate the replacement of thermal fission reactors by fast fission reactors that operate on a self-sufficient closed fuel cycle. This replacement might take place within the next one hundred years, so the direct competitors of fusion reactors will be fission reactors of the latter rather than the former type. Also, fast fission reactors, in contrast to thermal fission reactors, have the potential for transmuting long-lived actinides into short-lived fission products. The associated reduction of the long-term activation of radioactive waste due to actinides makes the comparison of radioactive waste from fast fission reactors to that from fusion reactors more rewarding than the comparison of radioactive waste from thermal fission reactors to that from fusion reactors. Radioactive waste from an experimental and a commercial fast fission reactor and an experimental and a commercial fusion reactor has been characterized. The fast fission reactors chosen for this study were the Experimental Breeder Reactor 2 and the Integral Fast Reactor. The fusion reactors chosen for this study were the International Thermonuclear Experimental Reactor and a Reduced Activation Ferrite Helium Tokamak. The comparison of radioactive waste parameters shows that radioactive waste from the experimental fast fission reactor may be less hazardous than that from the experimental fusion reactor. Inclusion of the actinides would reverse this conclusion only in the long-term. Radioactive waste from the commercial fusion reactor may always be less hazardous than that from the commercial fast fission reactor, irrespective of the inclusion or exclusion of the actinides. The fusion waste would even be far less hazardous, if advanced structural materials, like silicon carbide or vanadium alloy, were employed.

  19. Fission product and actinide data evaluations for ENDF/B--V

    International Nuclear Information System (INIS)

    Schenter, R.E.

    1978-05-01

    The planned content and performance of fission product and actinide nuclide evaluations for the ENDF/B-V collection of data are reviewed. Representative values of parameters for a few nuclides are shown. 10 figures, 5 tables

  20. Measurement of cross-sections of fission reactions induced by neutrons on actinides from the thorium cycle at n-TOF facility; Mesures de sections efficaces de fission induite par neutrons sur des actinides du cycle du thorium a n-TOF

    Energy Technology Data Exchange (ETDEWEB)

    Ferrant, L

    2005-09-01

    In the frame of innovating energy source system studies, thorium fuel cycle reactors are considered. Neutron induced fission cross section on such cycle involved actinides play a role in scenario studies. To feed them, data bases are built with experimental results and nuclear models. For some nuclei, they are not complete or in disagreement. In order to complete these data bases, we have built an original set up, consisting in an alternation of PPACs (Parallel Plate Avalanche Chamber) and ultra - thin targets, which we installed on n-TOF facility. We describe detectors, set up, and the particular care brought to target making and characterization. Fission products in coincidence are detected with precise time measurement and localization with delay line read out method. We contributed, within the n-TOF collaboration, to the CERN brand new intense spallation neutron source characterization, based on time of flight measurement, and we describe its characteristics and performances. We were able to measure such actinide fission cross sections as {sup 232}Th, {sup 234}U, {sup 233}U, {sup 237}Np, {sup 209}Bi, and {sup nat}Pb relative to {sup 235}U et {sup 238}U standards, using an innovative acquisition system. We took advantage of the lame accessible energy field, from 0.7 eV to 1 GeV, combined with the excellent energy resolution in this field. Data treatment and analysis advancement are described to enlighten performance and limits of the obtained results. (author)

  1. Role of ternary fission in synthesis of bypassed nuclei

    International Nuclear Information System (INIS)

    Kramarovskij, Ya.M.; Chechev, V.P.

    1983-01-01

    A possible influence of ternary fission with escape of neutron-enriched light charged particles on the synthesis of bypassed nuclides is considered. It is shown that this concept cannot give explanation of bypassed isotope concentrations, but it can make some contribution, if the probability of ternary fission for superheavy nuclei grows sharply with Z 2 /A parameter. The account of β-delayed fission contributes to the shift of ternary fission fragments into the region of neutron-deficient isotopes. Consistent consideration of the ternary fission role in the nucleosynthesis is possible only with an important accumulation of experimental and theoretical data on this process, particularly for the nuclei with Z > 100

  2. Recycling of actinides and fission products, the Dutch RAS research programme

    Energy Technology Data Exchange (ETDEWEB)

    Abrahams, K; Cordfunke, E H.P.; Franken, W M.P.; Gruppelaar, H; Kloosterman, J L; Konings, R J.M.; Versteegh, A M

    1994-08-01

    An ECN, a research programme has been started to contribute to current international research efforts in the field of P and T. The name of this programme is RAS, which is the dutch acronym for recycling of actinides and fission products. This multidisciplinary programme consists of the following components: - Nuclear data (`cross-section libraries`) - Reactor physics and scenario studies - Chemical studies (`actinide chemistry`) - Technological studies and irradiations. (orig./HP).

  3. Decay and fission of the oriented nuclei

    CERN Document Server

    Kadmenskij, S G

    2002-01-01

    The fragment angular distributions for binary decay of oriented spherical and deformed nuclei with taking into account the correct transformational properties of wave functions under time inversion have been investigated. It has been shown that for description of fragment angular distributions the adiabatic approximation for collective rotational nuclear degrees of freedom is not correct. It has been demonstrated that this approximation is valid for description of spontaneous and induced low-energy nuclear fission. The dependence of partial fission widths on the orientation of the internal axes spins, projections of spins, and relative angular moments of fission fragments has been analyzed. It has been shown that the adiabatic approximation results in coherent interference of wave functions of fragments relative movement. This interference forms fragments the universal angular distributions of fission fragments for oriented nuclei. For these distributions the deviations from A. Bohr's formula have been invest...

  4. Comparison of actinides and fission products recycling scheme with the normal plutonium recycling scheme in fast reactors

    Directory of Open Access Journals (Sweden)

    Salahuddin Asif

    2013-01-01

    Full Text Available Multiple recycling of actinides and non-volatile fission products in fast reactors through the dry re-fabrication/reprocessing atomics international reduction oxidation process has been studied as a possible way to reduce the long-term potential hazard of nuclear waste compared to that resulting from reprocessing in a wet PUREX process. Calculations have been made to compare the actinides and fission products recycling scheme with the normal plutonium recycling scheme in a fast reactor. For this purpose, the Karlsruhe version of isotope generation and depletion code, KORIGEN, has been modified accordingly. An entirely novel fission product yields library for fast reactors has been created which has replaced the old KORIGEN fission products library. For the purposes of this study, the standard 26 groups data set, KFKINR, developed at Forschungszentrum Karlsruhe, Germany, has been extended by the addition of the cross-sections of 13 important actinides and 68 most important fission products. It has been confirmed that these 68 fission products constitute about 95% of the total fission products yield and about 99.5% of the total absorption due to fission products in fast reactors. The amount of fissile material required to guarantee the criticality of the reactor during recycling schemes has also been investigated. Cumulative high active waste per ton of initial heavy metal is also calculated. Results show that the recycling of actinides and fission products in fast reactors through the atomics international reduction oxidation process results in a reduction of the potential hazard of radioactive waste.

  5. Theoretical study of fission dynamics with muons

    International Nuclear Information System (INIS)

    Oberacker, V.E.; Umar, A.S.; Bottcher, C.; Strayer, M.R.; Maruhn, J.A.; Frankfurt Univ.

    1992-01-01

    Following muon capture by actinide atoms, some of the inner shell muonic transitions proceed by inverse internal conversion, i.e. the excitation energy of the muonic atom is transferred to the nucleus. In particular, the muonic E2:(3d→1s) transition energy is close to the peak of the isoscalar giant quadrupole resonance in actinide nuclei which exhibits a large fission width. Prompt fission in the presence of a bound muon allows us to study the dynamics of large-amplitude collective motion. We solve the time-dependent Dirac equation for the muonic spinor wave function in the Coulomb field of the fissioning nucleus on a 3-dimensional lattice and demonstrate that the muon attachment probability to the light fission fragment is a measure of the nuclear energy dissipation between the outer fission barrier and the scission point

  6. Helium and fission gas behaviour in magnesium aluminate spinel and zirconia for actinide transmutation

    NARCIS (Netherlands)

    Damen, P.M.G.

    2003-01-01

    In order to reduce the long-term radiotoxicity of spent nuclear fuel, many studies are performed on partitioning and transmutation of actinides. In such a scenario, the long-lived radio-isotopes (mostly actinides) are partitioned from the nuclear waste, and subsequently transmuted or fissioned in a

  7. Actinide and fission product separation and transmutation

    International Nuclear Information System (INIS)

    1991-01-01

    The first international information exchange meeting on actinide and fission product separation and transmutation, took place in Mito in Japan, on 6-8 November 1990. It starts with a number of general overview papers to give us some broad perspectives. Following that it takes a look at some basic facts about physics and about the quantities of materials it is talking about. Then it proceeds to some specific aspects of partitioning, starting with evolution from today commercially applied processes and going on to other possibilities. At the end of the third session it takes a look at the significance of partitioning and transmutation of actinides before it embarks on two sessions on transmutation, first in reactors and second in accelerators. The last session is designed to throw back into the discussion the main points which need to be looked at when considering future work in this area. (A.L.B.)

  8. Actinide and fission product separation and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-07-01

    The first international information exchange meeting on actinide and fission product separation and transmutation, took place in Mito in Japan, on 6-8 November 1990. It starts with a number of general overview papers to give us some broad perspectives. Following that it takes a look at some basic facts about physics and about the quantities of materials it is talking about. Then it proceeds to some specific aspects of partitioning, starting with evolution from today commercially applied processes and going on to other possibilities. At the end of the third session it takes a look at the significance of partitioning and transmutation of actinides before it embarks on two sessions on transmutation, first in reactors and second in accelerators. The last session is designed to throw back into the discussion the main points which need to be looked at when considering future work in this area. (A.L.B.)

  9. A new type of active actinide target for studying fission and (n,xn) reactions

    International Nuclear Information System (INIS)

    Belier, G.; Aupiais, J.; Varignon, C.; Vayre, S.

    2011-01-01

    A new type of active target for the detection of fission of actinides has been developed, it is based on α spectrometry through liquid scintillation. The target uses the liquid-liquid extraction in order to mix the actinide with the liquid organic scintillator. The actinide to be detected is inside the detector itself which maximises the efficiency of the detector. The use of an organic scintillator allows the identification of the particles emitted. Indeed, the time delay for the transfer of the energy deposited in the solvent towards the scintillating molecules depends on the type of the energy deposits: instantaneous fluorescence is obtained for direct excitation while delayed fluorescence is obtained for energy deposits through ionization. By discriminating the different slow and quick components of the photomultiplier signal it is then possible to identify the particle: beta, alpha or fission products. This target has been tested with Cf 252 irradiated with 18 MeV neutrons, the experimental data show different peaks corresponding to alpha decay (97%), spontaneous fission (3%), beta decay and recoil protons due to neutron emissions. (A.C.)

  10. Electrochemical separation of actinides and fission products in molten salt electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Gay, R.L.; Grantham, L.F.; Fusselman, S.P. [Rockwell International/Rocketdyne Division, Canoga Park, CA (United States)] [and others

    1995-10-01

    Molten salt electrochemical separation may be applied to accelerator-based conversion (ABC) and transmutation systems by dissolving the fluoride transport salt in LiCl-KCl eutectic solvent. The resulting fluoride-chloride mixture will contain small concentrations of fission product rare earths (La, Nd, Gd, Pr, Ce, Eu, Sm, and Y) and actinides (U, Np, Pu, Am, and Cm). The Gibbs free energies of formation of the metal chlorides are grouped advantageously such that the actinides can be deposited on a solid cathode with the majority of the rare earths remaining in the electrolyte. Thus, the actinides are recycled for further transmutation. Rockwell and its partners have measured the thermodynamic properties of the metal chlorides of interest (rare earths and actinides) and demonstrated separation of actinides from rare earths in laboratory studies. A model is being developed to predict the performance of a commercial electrochemical cell for separations starting with PUREX compositions. This model predicts excellent separation of plutonium and other actinides from the rare earths in metal-salt systems.

  11. The resonance neutron fission on heavy nuclei

    International Nuclear Information System (INIS)

    Kopach, Yu.N.; Popov, A.B.; Furman, V.I.; Alfimenkov, V.P.; Lason', L.; Pikel'ner, L.B.; ); Gonin, N.N.; Kozlovskij, L.K.; Tambovtsev, D.I.; Gagarskij, A.M.; Petrov, G.A.; Sokolov, V.E.

    2001-01-01

    A new approach to the description of the fission, similar to the well-known reaction theory and based on the helicity representation for the exit fission channels, is briefly summarized. This approach allows one to connect the multimodal fission representation with A. Bohr's concept of the fission transition states and to obtain formulae for the partial and differential fission cross sections. The formulae are used for analysis of the angular anisotropy of fragments in the neutron resonance induced fission of aligned 235 U nuclei and of the P-even angular forward-backward and right-left correlations of fragments oe the P-odd correlations caused by the interference of s- and p-wave neutron resonances [ru

  12. Antiproton Induced Fission and Fragmentation of Nuclei

    CERN Multimedia

    2002-01-01

    The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...

  13. Determination of minor actinides fission cross sections by means of transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Jurado, B.; Aiche, M.; Barreau, G.; Boyer, S.; Czajkowski, S.; Dassie, D.; Grosjean, C.; Guiral, A.; Haas, B.; Osmanov, B.; Petit, M. [CENBG - UMR 5795 CNRS/IN2P3-Univ. Bordeaux 1- Le Haut Vigneau, 33175 Gradignan (France); Berthoumieux, E.; Gunsing, F.; Perrot, L.; Theisen, Ch. [CEN Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette cedex (France); Bauge, E. [CEA, SPhN, BP12 91680 Bruyeres-le-Chatel (France); Michel-Sendis, F. [IPN, 15 rue G. Clemenceau, 91406 Orsay cedex (France); Billebaud, A. [LPSC, 53 Avenue des Martyrs, 38026 Grenoble cedex (France); Wilson, J. N. [IPN, 15 rue G. Clemenceau, 91406 Orsay cedex (France); LPSC, 53 Avenue des Martyrs, 38026 Grenoble cedex (France); Ahmad, I.; Greene, J.P.; Janssens, R. V. F. [ANL, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

    2005-07-01

    We present an original method that allows to determine neutron-induced cross sections of very short-lived minor actinides. This indirect method, based on the use of transfer reactions, has already been applied with success for the determination of the neutron-induced fission and capture cross section of {sup 233}Pa, a key nucleus in the {sup 232}Th - {sup 233}U fuel cycle. A recent experiment using this technique has been performed to determine the neutron-induced fission cross sections of {sup 242,243,244}Cm and {sup 241}Am which are present in the nuclear waste of the current U-Pu fuel cycle. These cross sections are highly relevant for the design of reactors capable to incinerate minor actinides. The first results will be illustrated. (authors)

  14. Fission times of excited nuclei: An experimental overview

    International Nuclear Information System (INIS)

    Morjean, M.; Morjean, M.; Jacquet, D.

    2009-01-01

    An overview of selected recent experimental results on fission times is presented. Evidences for over-damped motion up to saddle point during the fission process of highly excited nuclei have been obtained independently through fission probability, pre-scission multiplicity and direct time measurements. In addition, strong clues have been found for a temperature dependency of friction. Experiments probing transient effects through fission probabilities are presented and the counterbalanced effects of friction and level density parameters are discussed. Promising perspectives for super-heavy stability studies, based on fission time measurements, are presented. (authors)

  15. Measurement of cross-sections of fission reactions induced by neutrons on actinides from the thorium cycle at n-TOF facility

    International Nuclear Information System (INIS)

    Ferrant, L.

    2005-09-01

    In the frame of innovating energy source system studies, thorium fuel cycle reactors are considered. Neutron induced fission cross section on such cycle involved actinides play a role in scenario studies. To feed them, data bases are built with experimental results and nuclear models. For some nuclei, they are not complete or in disagreement. In order to complete these data bases, we have built an original set up, consisting in an alternation of PPACs (Parallel Plate Avalanche Chamber) and ultra - thin targets, which we installed on n-TOF facility. We describe detectors, set up, and the particular care brought to target making and characterization. Fission products in coincidence are detected with precise time measurement and localization with delay line read out method. We contributed, within the n-TOF collaboration, to the CERN brand new intense spallation neutron source characterization, based on time of flight measurement, and we describe its characteristics and performances. We were able to measure such actinide fission cross sections as 232 Th, 234 U, 233 U, 237 Np, 209 Bi, and nat Pb relative to 235 U et 238 U standards, using an innovative acquisition system. We took advantage of the lame accessible energy field, from 0.7 eV to 1 GeV, combined with the excellent energy resolution in this field. Data treatment and analysis advancement are described to enlighten performance and limits of the obtained results. (author)

  16. Actinide Capture and Fission Cross Section Measurements Within the Mini-Inca Project

    International Nuclear Information System (INIS)

    Letourneau, A.

    2006-01-01

    Full text of publication follows: The Mini-INCA project is devoted to precise description of the transmutation chain of Actinides within high thermal neutron fluxes. It uses the High Flux Reactor of ILL (Laue Langevin Institute) as an intense thermal neutron source to measure capture and fission cross sections. Two irradiation channels are dedicated for those measurements offering a diversity of fluxes ranging from pure thermal neutrons to 15% epithermal neutrons with intensities as high as 1*10 15 n/cm 2 /s. Standard nuclear techniques for measurements, such as α and γ-spectroscopy of irradiated samples, have been extended in order to stand all constraints due to the irradiation in high fluxes. In particular new types of fission micro-chambers have been developed to follow online the evolution of one actinide and to measure its fission cross section in reference to 235 U(n,F) standard reaction. This type of neutron detector will be used within the MEGAPIE target to on-line characterise the neutron flux and to study the potentiality of such target in terms of incineration. (author)

  17. Fission mass yields of excited medium heavy nuclei

    International Nuclear Information System (INIS)

    Sandulescu, A.; Depta, K.; Herrmann, R.; Greiner, W.; Scheid, W.

    1985-01-01

    The mass distributions resulting from the fission of excited medium mass nuclei are discussed on the basis of the fragmentation theory. It is shown that very asymmetric fission events can be expected with rates which are only a few orders of magnitude smaller than the rates for symmetric fission. As an example a calculation of the fission mass distribution of the excited 172 Yb compound nucleus is presented. This mass distribution reveals observable structures over the entire range of the mass asymmetry due to valleys in the potential energy surface for fission fragments with closed proton and neutron shells

  18. Status of the French research programme for actinides and fission products partitioning and transmutation

    International Nuclear Information System (INIS)

    Warin, D.

    2003-01-01

    The paper focus on separation and transmutation research and development programme and main results over these ten last years. The massive research programme on enhanced separation, conducted by CEA and supported by broad international cooperation, has recently achieved some vital progress. Based on real solutions derived from the La Hague process, the CEA demonstrated the lab-scale feasibility of extracting minor actinides and some fission products (I, Cs and Tc) using an hydrometallurgical process that can be extrapolated on the industrial scale. The CEA also conducted programmes proving the technical feasibility of the elimination of minor actinides and fission products by transmutation: fabrication of specific targets and fuels for transmutation tests in the HFR and Phenix reactors, neutronics and technology studies for ADS developments in order to support the MEGAPIE, TRADE and MYRRHA experiments and the future 100 MW international ADS demonstrator. Scenarios studies aimed at stabilizing the inventory with long-lived radionuclides, plutonium, minor actinides and certain long-lived fission products in different nuclear power plant parks and to verify the feasibility at the level of the cycle facilities and fuels involved in those scenarios. Three French Research Groups CEA-CNRS carry out partitioning (PRACTIS) and transmutation (NOMADE and GEDEON) more basic studies. (author)

  19. Fission in a Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Younes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-26

    A three-year theory project was undertaken to study the fission process in extreme astrophysical environments, such as the crust of neutron stars. In the first part of the project, the effect of electron screening on the fission process was explored using a microscopic approach. For the first time, these calculations were carried out to the breaking point of the nucleus. In the second part of the project, the population of the fissioning nucleus was calculated within the same microscopic framework. These types of calculations are extremely computer-intensive and have seldom been applied to heavy deformed nuclei, such as fissioning actinides. The results, tools and methodologies produced in this work will be of interest to both the basic-science and nuclear-data communities.

  20. New type of asymmetric fission in proton-rich nuclei

    CERN Document Server

    Andreyev, A N; Huyse, M; Van Duppen, P; Antalic, S; Barzakh, A; Bree, N; Cocolios, T E; Comas, V F; Diriken, J; Fedorov, D; Fedosseev, V; Franchoo, S; Heredia, J A; Ivanov, O; Koster, U; Marsh, B A; Nishio, K; Page, R D; Patronis, N; Seliverstov, M; Tsekhanovich, I; Van den Bergh, P; Van De Walle, J; Venhart, M; Vermote, S; Veselsky, M; Wagemans, C; Ichikawa, T; Iwamoto, A; Moller, P; Sierk, A J

    2010-01-01

    A very exotic process of ${\\beta}$-delayed fission of $^{180}$Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post-${\\beta}$-decay daughter nucleus $^{180}$Hg (N/Z=1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two $^{90}$Zr fragments, with magic N=50 and semimagic Z=40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly measured branching ratio for $\\beta$-delayed fission of $^{180}$Tl is 3.6(7)×10$^{-3}$%, approximately 2 orders of magnitude larger than in an earlier study.

  1. The Metabolic Properties of the Fission Products and Actinide Elements

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton M.D., J.G.

    1948-03-01

    An investigation of the assimilation, distribution, retention, an excretion of the fission products and actinide elements in the rat has been conducted at the Crocker Radiation Laboratory, University of California, Berkeley, California. These studies were initiated October 15, 1942, and are continuing at the present time. An extensive survey has been made of the metabolism of twenty-two different radio elements in the rat.

  2. MIGRATION '03: 9th International Conference on Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere

    International Nuclear Information System (INIS)

    Kim, Geon Young; Hahn, Pil Soo; Kang, Moon Ja; Baik, Min Hoon; Kim, Seung

    2003-12-01

    The objectives of this report are overview of the chemistry and migration behavior of actinide for the HLW disposal safety assessment and to summarise the present status of actinide science and future developments. Actinides in HLW are very toxic and long-life time radionuclides. Therefore, the understanding of their characteristics and reaction behaviors in the deep subsurface environment is necessary for improving the reliability of HLW disposal safety assessment. This report presents an overview of the recent developments in the fundamental chemistry of actinides and fission products in natural aquifer systems, their interactions and migration in the geosphere, and the processes involved in modeling their geochemical behavior for the high level radioactive waste management. In addition, the thesis presented in MIGRATION '03 conference were described briefly. Actinide science in relation to the HLW disposal management can be classified into three main subjects; aquatic chemistry of actinides and fission products, migration behavior of radionuclides and geochemical and transport modeling. The radionuclides leached from waste forms are intruded into human environment along the groundwater flowing in the fracture around the waster disposal facility. To analyze and predict such radionuclide migration phenomena, the data that were obtained from well defined condition are required. Data obtained from studies on the chemical behaviors of actinide elements and fission products in the groundwater are essential in the safety assessment of HLW management. This report is intended to suggest the direction of R and D in actinide chemistry for the national program of HLW management in future

  3. Photon and proton induced fission on heavy nuclei at intermediate energies

    Directory of Open Access Journals (Sweden)

    Andrade-II E.

    2014-04-01

    Full Text Available We present an analysis of fission induced by intermediate energy protons or photons on actinides. The 660 MeV proton induced reactions are on 241Am, 238U, and 237Np targets and the Bremmstrahlung-photons with end-point energies at 50 MeV and 3500 MeV are on 232Th and 238U targets. The study was performed by means of the Monte Carlo simulation code CRISP. A multimodal fission extension was added to the code within an approach which accounts for the contribution of symmetric and asymmetric fission. This procedure allowed the investigation of fission cross sections, fissility, number of evaporated nucleons and fission-fragment charge distributions. The comparison with experimental data show a good agreement between calculations and experiments.

  4. Study on decay of rare earth nuclei produced by fission

    Energy Technology Data Exchange (ETDEWEB)

    Kawade, Kiyoshi; Yamamoto, Hiroshi; Shibata, Michihiro; Asai, Masato [Nagoya Univ. (Japan); Tsukada, Kazuaki; Osa, Akihiko; Shinohara, Nobuo; Iimura, Hideki

    1996-01-01

    JAERI-ISOL utilizes charge particle induced fission by proton and heavy proton produced by the tandem type accelerator (JAERI). To study the decay mechanism and nuclei structure of neutron and excess nuclei produced by actinoid fission, JAERI-ISOL was improved by developing the multilayer target tank. So that, the intensity of mass separated ion beam increased enough to use. New 76.6 KeV {gamma}-ray with about 10s of half life was found in the preliminary experiment. (S.Y.)

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

    CERN Multimedia

    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.

  6. Photofissility of heavy nuclei at intermediate energies

    International Nuclear Information System (INIS)

    Deppman, A.; Arruda Neto, J.D.T.; Likhachev, V.P.; Goncalves, M.

    2002-10-01

    We use the recently developed MCMC/MCEF (Multi Collisional Monte Carlo plus Monte Carlo for Evaporation-Fission calculations) model to calculate the photo fissility and the photofission cross section at intermediate energies for the 243 Am and for 209 Bi, and compare them to results obtained for other actinides and to available experimental data. As expected, the results for 243 Am are close to those for 237 Np. The fissility for pre actinide nuclei is nearly one order of magnitude lower than that for the actinides. Both fissility and photofission cross section for 209 Bi are in good agreement with the experimental data. (author)

  7. Summary Report of Second Research Coordination Meeting on Prompt Fission Neutron Spectra of Major Actinides

    International Nuclear Information System (INIS)

    Capote Noy, R.

    2013-09-01

    A summary is given of the Second Research Coordination Meeting on Prompt Fission Neutron Spectra of Actinides. Experimental data and modelling methods on prompt fission neutron spectra were reviewed. Extensive technical discussions held on theoretical methods to calculate prompt fission spectra. Detailed coordinated research proposals have been agreed. Summary reports of selected technical presentations at the meeting are given. The resulting work plan of the Coordinated Research Programme is summarized, along with actions and deadlines. (author)

  8. Photon and proton induced fission on heavy nuclei at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Andrade-II, E.; Karapetyan, G.S.; Deppman, A.; Guimaraes, V. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica; Balabekyan, A.R. [Yerevan State University, Alex Manoogian 1, Yerevan (Armenia); Demekhina, N.A. [Yerevan Physics Institute, Alikhanyan Brothers 2, Yerevan (Armenia); Joint Institute for Nuclear Research (JINR), Flerov Laboratory of Nuclear Reactions (LNR), Moscow (Russian Federation)

    2014-07-01

    We present an analysis of fission induced by intermediate energy protons or photons on actinides. The 660 MeV proton induced reactions are on {sup 241}Am, {sup 238}U, and {sup 237}Np targets and the Bremsstrahlung-photons with end-point energies at 50 MeV and 3500 MeV are on {sup 232}Th and {sup 238}U targets. The study was performed by means of the Monte Carlo simulation code CRISP. A multimodal fission extension was added to the code within an approach which accounts for the contribution of symmetric and asymmetric fission. This procedure allowed the investigation of fission cross sections, fissility, number of evaporated nucleons and fission-fragment charge distributions. The comparison with experimental data show a good agreement between calculations and experiments. (author)

  9. MIGRATION '03: 9th International Conference on Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Geon Young; Hahn, Pil Soo; Kang, Moon Ja; Baik, Min Hoon; Kim, Seung

    2003-12-15

    The objectives of this report are overview of the chemistry and migration behavior of actinide for the HLW disposal safety assessment and to summarise the present status of actinide science and future developments. Actinides in HLW are very toxic and long-life time radionuclides. Therefore, the understanding of their characteristics and reaction behaviors in the deep subsurface environment is necessary for improving the reliability of HLW disposal safety assessment. This report presents an overview of the recent developments in the fundamental chemistry of actinides and fission products in natural aquifer systems, their interactions and migration in the geosphere, and the processes involved in modeling their geochemical behavior for the high level radioactive waste management. In addition, the thesis presented in MIGRATION '03 conference were described briefly. Actinide science in relation to the HLW disposal management can be classified into three main subjects; aquatic chemistry of actinides and fission products, migration behavior of radionuclides and geochemical and transport modeling. The radionuclides leached from waste forms are intruded into human environment along the groundwater flowing in the fracture around the waster disposal facility. To analyze and predict such radionuclide migration phenomena, the data that were obtained from well defined condition are required. Data obtained from studies on the chemical behaviors of actinide elements and fission products in the groundwater are essential in the safety assessment of HLW management. This report is intended to suggest the direction of R and D in actinide chemistry for the national program of HLW management in future.

  10. Thermal neutron actinide data

    International Nuclear Information System (INIS)

    Tellier, H.

    1992-01-01

    During the 70's, the physicists involved in the cross section measurements for the low energy neutrons were almost exclusively interested in the resonance energy range. The thermal range was considered as sufficiently known. In the beginning of the 80's, reactor physicists had again to deal with the delicate problem of the power reactor temperature coefficient, essentially for the light water reactors. The measured value of the reactivity temperature coefficient does not agree with the computed one. The later is too negative. For obvious safety reasons, it is an important problem which must be solved. Several causes were suggested to explain this discrepancy. Among all these causes, the spectral shift in the thermal energy range seems to be very important. Sensibility calculations shown that this spectral shift is very sensitive to the shape of the neutron cross sections of the actinides for energies below one electron-volt. Consequently, reactor physicists require new and accurate measurements in the thermal and subthermal energy ranges. A part of these new measurement results were recently released and reviewed. The purpose of this study is to complete the preceding review with the new informations which are now available. In reactor physics the major actinides are the fertile nuclei, uranium 238, thorium 232 and plutonium 240 and the fissile nuclei, uranium 233, uranium 235 and plutonium 239. For the fertile nuclei the main datum is the capture cross section, for the fissile nuclei the data of interest are nu-bar, the fission and capture cross sections or a combination of these data such as η or α. In the following sections, we will review the neutron data of the major actinides for the energy below 1 eV

  11. Fusion-fission of superheavy nuclei at low excitation energies

    International Nuclear Information System (INIS)

    Itkis, M.G.; Oganesyan, Yu.Ts.; Kozulin, E.M.

    2000-01-01

    The process of fusion-fission of superheavy nuclei with Z = 102 -122 formed in the reactions with 22 Ne, 26 Mg, 48 Ca, 58 Fe and 86 Kr ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) using a time-of-flight spectrometer of fission fragments CORSET and a neutron multi-detector DEMON. As a result of the experiments, mass and energy distributions of fission fragments, fission and quasi-fission cross sections, multiplicities of neutrons and gamma-rays and their dependence on the mechanism of formation and decay of compound superheavy systems have been studied

  12. Fusion probability and survivability in estimates of heaviest nuclei production

    International Nuclear Information System (INIS)

    Sagaidak, Roman

    2012-01-01

    A number of theoretical models have been recently developed to predict production cross sections for the heaviest nuclei in fusion-evaporation reactions. All the models reproduce cross sections obtained in experiments quite well. At the same time they give fusion probability values P fus ≡ P CN differed within several orders of the value. This difference implies a corresponding distinction in the calculated values of survivability. The production of the heaviest nuclei (from Cm to the region of superheavy elements (SHE) close to Z = 114 and N = 184) in fusion-evaporation reactions induced by heavy ions has been considered in a systematic way within the framework of the barrier-passing (fusion) model coupled with the standard statistical model (SSM) of the compound nucleus (CN) decay. Both models are incorporated into the HIVAP code. Available data on the excitation functions for fission and evaporation residues (ER) produced in very asymmetric combinations can be described rather well within the framework of HIVAP. Cross-section data obtained in these reactions allow one to choose model parameters quite definitely. Thus one can scale and fix macroscopic (liquid-drop) fission barriers for nuclei involved in the evaporation-fission cascade. In less asymmetric combinations (with 22 Ne and heavier projectiles) effects of fusion suppression caused by quasi-fission are starting to appear in the entrance channel of reactions. The P fus values derived from the capture-fission and fusion-fission cross-sections obtained at energies above the Bass barrier were plotted as a function of the Coulomb parameter. For more symmetric combinations one can deduce the P fus values semi-empirically, using the ER and fission excitation functions measured in experiments, and applying SSM model with parameters obtained in the analysis of a very asymmetric combination leading to the production of (nearly) the same CN, as was done for reactions leading to the pre-actinide nuclei formation

  13. Properties of neutron-rich nuclei studied by fission product nuclear chemistry

    International Nuclear Information System (INIS)

    Meyer, R.A.; Henry, E.A.; Griffin, H.C.; Lien, O.G. III; Lane, S.M.; Stevenson, P.C.; Yaffe, R.P.; Skarnemark, G.

    1979-09-01

    A review is given of the properties of neutron-rich nuclei studied by fission product nuclear chemistry and includes the techniques used in elemental isolation and current research on the structure of nuclei near 132 Sn, particle emission, and coexisting structure in both neutron-poor and neutron-rich nuclei. 35 references

  14. Systematics of criticality properties of actinide nuclides and its bearing on the long lived fission waste problem

    International Nuclear Information System (INIS)

    Srinivasan, M.; Rao, K.S.; Garg, S.B.; Iyengar, P.K.

    1989-01-01

    This paper reports on a systematic analysis of the criticality parameters of over twenty fissile and fertile isotopes of eight transthorium actinide elements that has been carried out by us. It is observed that K ∞ increases and critical mass decreases monotonically with the fissility parameter (Z 2 /A) of the nuclides. This implies that each and every isotope of transuranic elements such as Np, Am, Cm etc. which are produced as by-products during reactor operation is a more valuable nuclear fuel than the corresponding fissile/fissible isotopes of plutonium. This finding has a profound bearing on the long lived fission waste problem and supports the view that the byproduct actinide elements should be separated from the high level waste stream and recycled back into fission reactors, thereby eliminating one of the commonly voiced concerns regarding the acceptability of nuclear fission power

  15. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: the EXILL campaign

    Directory of Open Access Journals (Sweden)

    de France G.

    2014-03-01

    Full Text Available A combination of germanium detectors has been installed at the PF1B neutron guide of the ILL to perform the prompt spectroscopy of neutron-rich nuclei produced in the neutron-capture induced-fission of 235U and 241Pu. In addition LaBr3 detectors from the FATIMA collaboration have been installed in complement with the EXOGAM clovers to measure lifetimes of low-lying excited states. The measured characteristics and online spectra indicate very good performances of the overall setup.

  16. Partitioning of actinides and fission products using molten salt electrorefining process

    International Nuclear Information System (INIS)

    Barbero, Jose A.; Wiesztort, Andres; Azcona, Alejandra; Bollini, Edgardo; Forchetti, Alberto; Orce, Alan

    1999-01-01

    Electrorefining is the key step of pyrometallurgical processing for separating actinides from fission products. In this work, the electrorefining process is carried out in a electrorefining cell that contains molten salts (49% LiCl- 51% KCL) floating on a liquid cadmium. The cell is operated under an inert atmosphere at 500 degree C. In this work we describe in detail the construction of the cell and the way of operation

  17. On the possibility of unified description of fission and collision of nuclei

    International Nuclear Information System (INIS)

    Shigin, V.A.

    1978-01-01

    A system of two touching nuclei is comparatively stable against disintegration and fusion and unstable against chaotic nucleon exchange between the nuclei which can essentially change the size of the nuclei. These features of touching nuclei were used to suggest a fission mechanism involving production of a light nucleus (α particle) at the periphery of the compound nucleus, growth of the light nucleus caused by exchange of nucleons and subsequent disintegration into two nuclei. In this paper the potential relief of such a fission is presented. The life times of the system against disintegration, fusion, exchange by a nucleon and change of the nuclear sizes are estimated. It is shown that the behaviour of colliding nuclei after nearing is determined by the same potential relief and exchange by nucleons. Formation of the compound nucleus is explained due to transition of nucleons from one nucleus into another

  18. Status of nuclear data for actinides

    Energy Technology Data Exchange (ETDEWEB)

    Guzhovskii, B.Y.; Gorelov, V.P.; Grebennikov, A.N. [Russia Federal Nuclear Centre, Arzamas (Russian Federation)] [and others

    1995-10-01

    Nuclear data required for transmutation problem include many actinide nuclei. In present paper the analysis of neutron fission, capture, (n,2n) and (n,3n) reaction cross sections at energy region from thermal point to 14 MeV was carried out for Th, Pa, U, Np, Pu, Am and Cm isotops using modern evaluated nuclear data libraries and handbooks of recommended nuclear data. Comparison of these data indicates on substantial discrepancies in different versions of files, that connect with quality and completeness of original experimental data.

  19. Evidence of pair correlations in actinide neutron-induced fission cross sections

    International Nuclear Information System (INIS)

    Maslov, V.M.

    2000-01-01

    It is shown that irregularities in fission cross sections in MeV incident neutron energy region could be attributed to the interplay of few-quasiparticle excitations in the level density of the fissioning and residual nuclei. It is suggested the intrinsic quasiparticle state density modelling approach both at stable and saddle-point deformations. The experimental manifestation of few-quasiparticle irregularities in the level density depends on the fission barrier structure and internal excitation energy at the saddle point, corresponding to the higher barrier hump. The explicit evidence is observed in case of fissile and non-fissile target nuclides [ru

  20. Rupture of the neck in nuclear fission

    International Nuclear Information System (INIS)

    Davies, K.T.R.; Managan, R.A.; Nix, J.R.; Sierk, A.J.

    1977-01-01

    We introduce a degree of freedom to describe the rupture of the neck in nuclear fission and calculate the point at which the neck ruptures as the nucleus descends dynamically from its fission saddle point. This is done by mentally slicing the system into two portions at its minimum neck radius and calculating the force required to separate the two portions while keeping their shapes fixed. This force is obtained by differentiating with respect to separation the sum of the Coulomb and nuclear interaction energies between the two portions. For nuclei throughout the Periodic Table we calculate this force along dynamical paths leading from the fission saddle point. The force is initially attractive but becomes repulsive when the neck reaches a critical size. For actinide nuclei the neck radius at which rupture occurs is about 2 fm. This increases the calculated translational kinetic energy of the fission fragments at infinity relative to that calculated for scission occurring at zero neck radius. With the effect of neck rupture taken into account, we calculate and compare with experimental results fission-fragment kinetic energies for two types of nuclear dissipation: ordinary two-body viscosity and one-body dissipation

  1. Critical angular momentum dependence of the fission barriers and the stability of superheavy nuclei

    International Nuclear Information System (INIS)

    Magda, M.T.; Sandulescu, A.

    1978-10-01

    Measured complete fusion and evaporation cross section data are used to determine the critical angular momenta for which the fission barriers are vanishing in the region of nuclei with Z = 102 - 116. It is shown that, in order to fit these data, larger values of the critical angular momenta are obtained for superheavy nuclei (Z = 110 - 112) than for heavy ones (Z = 102 - 107), which indicates a relatively higher stability against fission for superheavy nuclei, in agreement with the theoretically predicted island of stability. (author)

  2. New fission valley for 258Fm and nuclei beyond

    International Nuclear Information System (INIS)

    Moeller, P.; Nix, J.R.; Swiatecki, W.J.

    1986-01-01

    Experimental results on the fission properties of nuclei close to 264 Fm show sudden and large changes with a change of only one or two neutrons or protons. The nucleus 258 Fm, for instance, undergoes symmetric fission with a half-life of about 0.4 ms and a kinetic energy peaked at about 235 MeV whereas 256 Fm undergoes asymmetric fission with a half-life of about 3 h and a kinetic energy peaked at about 200 MeV. Qualitatively, these sudden changes hve been postulated to be due to the emergence of fragment shells in symmetric fission products close to 132 Sn. A quantitative calculation that shows where high-kinetic-energy symmetric fission occurs and why it is associated with a sudden and large decrease in fission half-lives. The study is based on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. The implications of the new fission valley on the stability of the heaviest elements is discussed. 33 refs., 12 figs

  3. Spontaneous-fission half-lives for even nuclei with Z> or =92

    International Nuclear Information System (INIS)

    Randrup, J.; Larsson, S.E.; Moller, P.; Nilsson, S.G.; Pomorski, K.; Sobiczewski, A.

    1976-01-01

    The spontaneous-fission process for doubly even nuclei with Z> or =92 is studied in a semiempirical WKB framework. One-dimensional fission barrier potentials are established from theoretical deformation-energy surfaces based on the droplet model and the modified-oscillator model. The effects of axial asymmetry as well as reflection asymmetry have been taken into account. Macroscopic (irrotational flow) inertial-mass functions and, alternatively, microscopic (cranking model) inertial mass parameters have been employed for the calculation of the fission half-lives. With one over-all normalization parameter it is possible to fit the experimental half-lives to within a factor of 20 on the average. The resulting effective inertial-mass functions are used to estimate the stability of the transactinide elements. Only minor differences with previous estimates for the r process and superheavy nuclei are encountered

  4. Separation of actinides and long-lived fission products from high-level radioactive wastes (a review)

    International Nuclear Information System (INIS)

    Kolarik, Z.

    1991-11-01

    The management of high-level radioactive wastes is facilitated, if long-lived and radiotoxic actinides and fission products are separated before the final disposal. Especially important is the separation of americium, curium, plutonium, neptunium, strontium, cesium and technetium. The separated nuclides can be deposited separately from the bulk of the high-level waste, but their transmutation to short-lived nuclides is a muchmore favourable option. This report reviews the chemistry of the separation of actinides and fission products from radioactive wastes. The composition, nature and conditioning of the wastes are described. The main attention is paid to the solvent extraction chemistry of the elements and to the application of solvent extraction in unit operations of potential partitioning processes. Also reviewed is the behaviour of the elements in the ion exchange chromatography, precipitation, electrolysis from aqueous solutions and melts, and the distribution between molten salts and metals. Flowsheets of selected partitioning processes are shown and general aspects of the waste partitioning are shortly discussed. (orig.) [de

  5. Calculation characterization of spent fuel hazard related to partitioning and transmutation of minor actinides and fission products

    International Nuclear Information System (INIS)

    Gerasimov, A. S.; Bergelson, B. R.; Tikhomirov, G.V.; Volovik, A.I. . E-mail of corresponding author: geras@itep.ru; Gerasimov, A.S.)

    2005-01-01

    Radiotoxicity is one of important characteristics of radwaste hazard. Radiotoxicity of actinides and fission products from spent fuel of VVER-1000 reactor for processes of burnup, long-term storage, and transmutation is discussed. (author)

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

    International Nuclear Information System (INIS)

    Nakagawa, Tsuneo; Iwamoto, Osamu

    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. (author)

  7. Geochemistry of actinides and fission products in natural aquifer systems

    International Nuclear Information System (INIS)

    Kim, J.I.

    1989-06-01

    The progress in the research area of the community project MIRAGE: 'Geochemistry of actinides and fission products in natural aquatic systems' has been reviewed. This programme belongs to a specific research and technical development programme for the European Atomic Energy Community in the field of management and storage of radioactive waste. The review summarizes research progresses in subject areas: complexation with organics, colloid generation in groundwater and basic retention mechanisms in the framework of the migration of radionuclides in the geosphere. The subject areas are being investigated by 23 laboratories under interlaboratory collaborations or independent studies. (orig.)

  8. Features of the neutron spectra accompanying the fission of actinide nuclei

    International Nuclear Information System (INIS)

    Lovchikova, G.N.; Trufanov, A.M.; Svirin, M.I.; Polyakov, A.V.; Vinogradov, V.A.; Dmitriev, V.D.; Boykov, G.S.

    2000-01-01

    The spectra of fission neutrons from 238 U are measured by the time-of-flight technique at incident-neutron energies E n = 5.0 and 13.2 MeV. The data are compared with those obtained in the previous studies for 232 Th, 235,238 U, 237 Np at E n = 2.9 and 14.7 MeV; for 232 Th at E n = 14.6 and 17.7 MeV; for 238 U at 16.0 and 17.7 MeV. An excess of soft neutrons, which is observed in comparing experimental spectra for E n 13.2, 14.7, 16.0 and 17.7 MeV with the results of traditional theoretical calculations, is reproduced fairly well under the assumption that, at high excitation energies of a compound system, some part of post-fission neutrons can be emitted by nonaccelerated fragments [ru

  9. Transmutation of nuclear waste. Status report RAS programme 1994: Recycling and transmutation of actinides and fission products

    Energy Technology Data Exchange (ETDEWEB)

    Cordfunke, E H.P.; Gruppelaar, H; Franken, W M.P.

    1995-07-01

    This report describes the status and progress of the Dutch RAS programme on `Recycling and Transmutation of Actinides and Fission Products` over the year 1994, which is the first year of the second 4-year programme. This programme is outlined and a short progress report is given over 1994, including a listing of 23 reports and publications over the year 1994. Highlights of 1994 were: The completion of long-lived fission-product transmutation studies, the initiation of small-scale demonstration experiments in the HFR on Tc and I, the issue of reports on the potential of the ALMR (Advanced Liquid Metal Reactor) for transmutation adn the participation and international cooperation on irradiation experiments with actinides in inert matrices. The remaining chapters contain more extended contributions on recent developments and selected topics, under the headings: Benefits and risks of partitioning and transmutation, Perspective of chemical partitioning, Inert matrices, Evolutionary options (MOX), Perspective of heavy water reactors, Perspective of fast burners, Perspective of accelerator-based systems, Thorium cycle, Fission-product transmutation, End scenarios, and Executive summary and recommendations. (orig.).

  10. Transmutation of nuclear waste. Status report RAS programme 1994: Recycling and transmutation of actinides and fission products

    International Nuclear Information System (INIS)

    Cordfunke, E.H.P.; Gruppelaar, H.; Franken, W.M.P.

    1995-07-01

    This report describes the status and progress of the Dutch RAS programme on 'Recycling and Transmutation of Actinides and Fission Products' over the year 1994, which is the first year of the second 4-year programme. This programme is outlined and a short progress report is given over 1994, including a listing of 23 reports and publications over the year 1994. Highlights of 1994 were: The completion of long-lived fission-product transmutation studies, the initiation of small-scale demonstration experiments in the HFR on Tc and I, the issue of reports on the potential of the ALMR (Advanced Liquid Metal Reactor) for transmutation adn the participation and international cooperation on irradiation experiments with actinides in inert matrices. The remaining chapters contain more extended contributions on recent developments and selected topics, under the headings: Benefits and risks of partitioning and transmutation, Perspective of chemical partitioning, Inert matrices, Evolutionary options (MOX), Perspective of heavy water reactors, Perspective of fast burners, Perspective of accelerator-based systems, Thorium cycle, Fission-product transmutation, End scenarios, and Executive summary and recommendations. (orig.)

  11. Minor actinide transmutation using minor actinide burner reactors

    International Nuclear Information System (INIS)

    Mukaiyama, T.; Yoshida, H.; Gunji, Y.

    1991-01-01

    The concept of minor actinide burner reactor is proposed as an efficient way to transmute long-lived minor actinides in order to ease the burden of high-level radioactive waste disposal problem. Conceptual design study of minor actinide burner reactors was performed to obtain a reactor model with very hard neutron spectrum and very high neutron flux in which minor actinides can be fissioned efficiently. Two models of burner reactors were obtained, one with metal fuel core and the other with particle fuel core. Minor actinide transmutation by the actinide burner reactors is compared with that by power reactors from both the reactor physics and fuel cycle facilities view point. (author)

  12. Fission-evaporation competition in excited uranium and fermium nuclei

    International Nuclear Information System (INIS)

    Sagajdak, R.N.; Chepigin, V.I.; Kabachenko, A.P.

    1997-01-01

    The production cross sections and excitation functions for the 223-226 U neutron deficient isotopes have been measured in the 20 Ne+ 208 Pb and 22 Ne+ 208 Pb reactions for (4,5)n and (4-7)n evaporation channels of the de-excitation of the compound nuclei 228 U* and 230 U*, respectively. The present study considers in addition the de-excitation via the (5,6)n evaporation channels of the 224 U* compound nucleus formed in the 27 Al+ 197 Au reaction. The production cross sections of 247g,246 Fm formed after evaporation of (5,6)n and (7,8)n from the 252 Fm* and 254 Fm* compound nuclei produced in the 20 Ne+ 232 Th and 22 Ne+ 232 Th reactions were also measured respectively. The evaporation residues emerging from the target were separated in-flight from the projectiles and background reaction products by the electrostatic recoil separator VASSILISSA [1]. The investigation regards the U and Fm compound nuclei in the 40-80 MeV excitation energy range. For the analysis of the (Hl, xn) evaporation cross sections the advanced statistical model [2] calculations were used. The angular momentum dependence of the shell correction to the fission barrier, and the effects of the nuclear viscosity and dynamical deformation for these fissile excited nuclei are considered. The n /Γ t > values at the initial steps of the de-excitation cascade for the U and Fm compound nuclei were derived from the measured excitation functions and discussed from the point of view of the consequences for the fission process dynamics

  13. Phosphonates as alternative to tributyl phosphate for the separation of actinides from fission products

    International Nuclear Information System (INIS)

    Vyas, Chirag K.; Joshirao, Pranav M.; Manchanda, Vijay K.; Rao, C.V.S. Brahmmananda; Jayalakshmi, S.

    2015-01-01

    The present work investigates the role of increase in the basicity of organophosphorus extractant (dialkylalkyl phosphonates) on the uptake of actinides and fission products vis-a-vis tributyl phosphate (TBP), currently employed as a universal extractant. Two dialkylalkyl phosphonates viz. dibutylpropyl phosphonate (DBPrP) and dibutylpentyl phosphonate (DBPeP) were synthesized, characterized and evaluated for their solvent extraction behavior towards U(VI), Th(IV), Eu(III) and Tc(VII) in nitric acid medium ranging from 0.01-6 M. It was observed that increasing the basicity of the phosphoryl oxygen enhanced the uptake of the actinides and the distribution coefficient values were significantly larger as compared to TBP. The limiting organic concentration (LOC) value was estimated for Th(IV) for these extractants and compared with the TBP system. The separation factors of actinides with phosphonates over Tc(VII) are distinctly better than that with TBP.

  14. Fifth International Conference on Fission and Properties of Neutron-Rich Nuclei

    CERN Document Server

    Ramayya, A V; ICFN5

    2014-01-01

    These proceedings are the fifth in the series of International Conferences covering fission and properties of neutron-rich nuclei, which are at the forefront of nuclear research. The time interval of 5 years between each conference allows for significant new results to be achieved. Recently, world leaders in theory and experiments in research and the development of new facilities for research presented their latest results in areas such as synthesis of superheavy elements, new facilities for and recent results with radioactive ion beams, structure of neutron-rich nuclei, nuclear fission process, fission yields and nuclear astrophysics. This book is a major source of the latest research in these areas and plans for the future. The conference brought together a unique group of over 100 speakers including leaders from the major nuclear laboratories in Canada, China, France, Finland, Germany, Italy, Japan, Russia, Switerzland and the US along with leading research scientists from around the world.

  15. Heavy neutron-deficient radioactive beams: fission studies and fragment distributions

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, K.H.; Benlliure, J.; Heinz, A.; Voss, B. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Boeckstiegel, C.; Grewe, A.; Steinhaeuser, S.; Clerc, H.G.; Jong, M. de; Junghans, A.R.; Mueller, J. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Pfuetzner, M. [Warsaw Univ. (Poland). Inst. of Experimental Physics

    1998-02-01

    The secondary-beam facility of GSI Darmstadt was used to study the fission process of short-lived radioactive nuclei. Relativistic secondary projectiles were produced by fragmentation of a 1 A GeV {sup 238}U primary beam and identified in nuclear charge and mass number. Their production cross sections were determined, and the fission competition in the statistical deexcitation was deduced for long isotopical chains. New results on the enhancement of the nuclear level density in spherical and deformed nuclei due to collective rotational and vibrational excitations were obtained. Using these reaction products as secondary beams, the dipole giant resonance was excited by electromagnetic interactions in a secondary lead target, and fission from excitation energies around 11 MeV was induced. The fission fragments were identified in nuclear charge, and their velocity vectors were determined. Elemental yields and total kinetic energies have been determined for a number of neutron-deficient actinides and preactinides which were not accessible with conventional techniques. The characteristics of multimodal fission of nuclei around {sup 226}Th were systematically investigated and related to the influence of shell effects on the potential energy and on the level density between fission barrier and scission. A systematic view on the large number of elemental yields measured gave rise to a new interpretation of the enhanced production of even elements in nuclear fission and allowed for a new understanding of pair breaking in large-scale collective motion. (orig.)

  16. Actinide and fission product partitioning and transmutation. Status and assessment report

    International Nuclear Information System (INIS)

    1999-01-01

    Implementation and partitioning technology is intended to reduce the inventory of actinides and long-lived fission products in nuclear waste. Such technology can decrease hazards of pre-disposal waste management and of physical disturbance of a waste repository. An authoritative analysis is given of the technical, radiological and economic consequences of the proposed partitioning and transmutation operations on the present and future fuel cycle options. The report is subdivided to a general part for non-specialist readers, and to a technical systems analysis discussing issues on partitioning, transmutation and long-term waste management. (R.P.)

  17. Remarks on the fission barriers of super-heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Goethe-Universitaet Frankfurt, Institut fuer Physik, Frankfurt (Germany); Heinz, S.; Mann, R.; Maurer, J.; Muenzenberg, G.; Barth, W.; Dahl, L.; Kindler, B.; Kojouharov, I.; Lang, R.; Lommel, B.; Runke, J.; Scheidenberger, C.; Tinschert, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Antalic, S. [Comenius University, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); Eberhardt, K.; Thoerle-Pospiech, P.; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz (Germany); Grzywacz, R. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Knoxville, TN (United States); Hamilton, J.H. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Henderson, R.A.; Kenneally, J.M.; Moody, K.J.; Shaughnessy, D.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Miernik, K. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Warsaw, Warsaw (Poland); Miller, D. [University of Tennessee, Knoxville, TN (United States); Morita, K. [RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama (Japan); Nishio, K. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Popeko, A.G.; Yeremin, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Roberto, J.B.; Rykaczewski, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Uusitalo, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland)

    2016-04-15

    Shell-correction energies of super-heavy nuclei are approximated by using Q{sub α} values of measured decay chains. Five decay chains were analyzed, which start at the isotopes {sup 285}Fl, {sup 294}118, {sup 291}Lv, {sup 292}Lv and {sup 293}Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far. (orig.)

  18. Curves and tables of neutron cross sections of fission product nuclei in JENDL-3

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Tsuneo [ed.

    1992-06-15

    Neutron cross sections of 172 nuclei in the fission product region stored in JENDL-3 are shown in graphs and tables. The evaluation work of these nuclei was made by the Fission Product Nuclear Data Working Group of the Japanese Nuclear Data Committee, in the neutron energy region from 10{sup {minus}5} eV to 20 MeV. Almost of the cross section data reproduced in graphs in this report. The cross section averaged over 38 energy intervals are listed in a table. Shown in order tables are thermal cross sections, resonance integrals, Maxwellian neutron flux average cross sections, fission spectrum average cross sections, 14-MeV cross sections, one group average cross sections in neutron flux of typical types of fission reactors and average cross sections in the 30-keV Maxwellian spectrum.

  19. Curves and tables of neutron cross sections of fission product nuclei in JENDL-3

    International Nuclear Information System (INIS)

    Nakagawa, Tsuneo

    1992-06-01

    Neutron cross sections of 172 nuclei in the fission product region stored in JENDL-3 are shown in graphs and tables. The evaluation work of these nuclei was made by the Fission Product Nuclear Data Working Group of the Japanese Nuclear Data Committee, in the neutron energy region from 10 -5 eV to 20 MeV. Almost all the cross section data are reproduced in graphs in this report. The cross section averaged over 38 energy intervals are listed in a table. Shown in other tables are thermal cross sections, resonance integrals, Maxwellian neutron flux average cross sections, fission spectrum average cross sections, 14-MeV cross sections, one group average cross sections in neutron flux of typical types of fission reactors and average cross sections in the 30-keV Maxwellian spectrum. (author)

  20. The Peculiarities of the Production and Decay of Superheavy Nuclei

    International Nuclear Information System (INIS)

    Itkis, M. G.; Bogachev, A. A.; Itkis, I. M.; Jandel, M.; Kliman, J.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Rusanov, A. Ya.; Sagaidak, R. N.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Behera, B. R.; Corradi, L.; Fioretto, E.

    2006-01-01

    The interest in the study of the fission process of superheavy nuclei mainly deals with the opportunity to obtain information about the cross-section of the compound nucleus (CN) formation at excitation energies E*≅15-30 MeV. It allows one to estimate the survival probability of the superheavy composite system after evaporation of 1-3 neutrons, i.e. in 'cold' or 'warm' fusion reactions. However, in order to solve this problem deeper understanding of the coalescence processes between colliding nuclei, the competition between fusion-fission and quasi-fission processes is needed. The characteristics of both processes, their manifestation in the experimental observables and the relative contribution to the capture cross-section in dependence on the excitation energies, reaction entrance channel etc were investigated for a wide range of target-projectile combinations. Results of the experiments devoted to the study of the fusion-fission and quasi-fission processes in the reactions of the formation of the superheavy nuclei with Z = 102-122 are presented. The heavy ions 26Mg, 48Ca, 50Ti, 58Fe and 64Ni were used as projectiles. The choice of the reactions with 48Ca and actinide-targets was inspired by the experiments on the production of the isotopes 283112, 289114 and 283116 in Dubna using the same reactions. The 50Ti, 58Fe and 64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia) and the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) using the time-of-flight spectrometer of fission fragments CORSET. The role of the shell effects, the influence of the entrance channel asymmetry and the deformations of colliding nuclei on the mechanism of the fusion-fission and the competitive process of quasi-fission are discussed. The recent results on synthesis of

  1. Contributions to the theory of fission neutron emission

    International Nuclear Information System (INIS)

    Seeliger, D.; Maerten, H.; Ruben, A.

    1990-03-01

    This report gives a compilation of recent work performed at Technical University, Dresden by D. Seeliger, H. Maerten and A. Ruben on the topic of fission neutron emission. In the first paper calculated fission neutron spectra are presented using the temperature distribution model FINESSE for fissioning actinide nuclei. In the second paper, starting from a general energy balance, Terrell's approach is generalized to describe average fragment energies as a function of incident energy; trends of fragment energy data in the Th-Pu region are well reproduced. In the third contribution, prompt fission neutron spectra and fragment characteristics for spontaneous fission of even Pu-isotopes are presented and discussed in comparison with experimental data using a phenomenological scission point model including temperature dependent shell effects. In the fourth paper, neutron multiplicities and energy spectra as well as average fragment energies for incident energies from threshold to 20 MeV (including multiple-chance fission) for U-238 are compared with traditional data representations. (author). Refs, figs and tabs

  2. Review of the neutron capture process in fission reactors

    International Nuclear Information System (INIS)

    Poenitz, W.P.

    1981-07-01

    The importance of the neutron capture process and the status of the more important cross section data are reviewed. The capture in fertile and fissile nuclei is considered. For thermal reactors the thermal to epithermal capture ratio for 238 U and 232 Th remains a problem though some improvements were made with more recent measurements. The capture cross section of 238 U in the fast energy range remains quite uncertain and a long standing discrepancy for the calculated versus experimental central reaction rate ratio C28/F49 persists. Capture in structural materials, fission product nuclei and the higher actinides is also considered

  3. Probability of ternary fission of 93Nb andnat Ag nuclei induced by 0.8-1.8 GeV photons

    International Nuclear Information System (INIS)

    Lima, D.A. de; Milomen, W.C.C.; Tavares, O.A.P.

    1989-01-01

    The yields of ternary fission of 93 Nb and nat Ag nuclei induced by bremsstrahlung photons of 0.8, 1.0, 1.4 and 1.8 GeV end-point energies have been measured by using the 2 Π-forward geometry with thick target metal foils in contact with makrofol polycarbonate sheets as fission-track detectors. Absolute mean cross sections per photon in the range 0.8-1.8 GeV have been obtained as 0.3 ± 0.3 μb and 0.5 ± μb, respectively, for 93 Nb and nat Ag nuclei. These correspond to a probability of ternary fission of approx. 10 -5 for both nuclei. Results are discussed and compared with previous ternary fission data obtained for nuclei of A [pt

  4. Fission properties of superheavy nuclei for r -process calculations

    Science.gov (United States)

    Giuliani, Samuel A.; Martínez-Pinedo, Gabriel; Robledo, Luis M.

    2018-03-01

    We computed a new set of static fission properties suited for r -process calculations. The potential energy surfaces and collective inertias of 3640 nuclei in the superheavy region are obtained from self-consistent mean-field calculations using the Barcelona-Catania-Paris-Madrid energy density functional. The fission path is computed as a function of the quadrupole moment by minimizing the potential energy and exploring octupole and hexadecapole deformations. The spontaneous fission lifetimes are evaluated employing different schemes for the collective inertias and vibrational energy corrections. This allows us to explore the sensitivity of the lifetimes to those quantities together with the collective ground-state energy along the superheavy landscape. We computed neutron-induced stellar reaction rates relevant for r -process nucleosynthesis using the Hauser-Feshbach statistical approach and study the impact of collective inertias. The competition between different reaction channels including neutron-induced rates, spontaneous fission, and α decay is discussed for typical r -process conditions.

  5. Spectroscopy of few-particle nuclei around magic 132Sn from fission product γ-ray studies

    International Nuclear Information System (INIS)

    Zhang, C. T.

    1998-01-01

    We are studying the yrast structure of very neutron-rich nuclei around doubly magic 132 Sn by analyzing fission product γ-ray data from a 248 Cm source at Eurogam II. Yrast cascades in several few-valence-particle nuclei have been identified through γγ cross coincidences with their complementary fission partners. Results for two-valence-particle nuclei 132 Sb, 134 Te, 134 Sb and 134 Sn provide empirical nucleon-nucleon interactions which, combined with single-particle energies already known in the one-particle nuclei, are essential for shell-model analysis in this region. Findings for the N = 82 nuclei 134 Te and 135 I have now been extended to the four-proton nucleus 136 Xe. Results for the two-neutron nucleus 134 Sn and the N = 83 isotones 134 Sb, 135 Te and 135 I open up the spectroscopy of nuclei in the northeast quadrant above 132 Sn

  6. Accuracy Improvement of Neutron Nuclear Data on Minor Actinides

    Science.gov (United States)

    Harada, Hideo; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kimura, Atsushi; Terada, Kazushi; Nakao, Taro; Nakamura, Shoji; Mizuyama, Kazuhito; Igashira, Masayuki; Katabuchi, Tatsuya; Sano, Tadafumi; Takahashi, Yoshiyuki; Takamiya, Koichi; Pyeon, Cheol Ho; Fukutani, Satoshi; Fujii, Toshiyuki; Hori, Jun-ichi; Yagi, Takahiro; Yashima, Hiroshi

    2015-05-01

    Improvement of accuracy of neutron nuclear data for minor actinides (MAs) and long-lived fission products (LLFPs) is required for developing innovative nuclear system transmuting these nuclei. In order to meet the requirement, the project entitled as "Research and development for Accuracy Improvement of neutron nuclear data on Minor ACtinides (AIMAC)" has been started as one of the "Innovative Nuclear Research and Development Program" in Japan at October 2013. The AIMAC project team is composed of researchers in four different fields: differential nuclear data measurement, integral nuclear data measurement, nuclear chemistry, and nuclear data evaluation. By integrating all of the forefront knowledge and techniques in these fields, the team aims at improving the accuracy of the data. The background and research plan of the AIMAC project are presented.

  7. Fission properties of actinide nuclei from proton-induced fission at 26.5 and 62.9 MeV incident proton energies

    International Nuclear Information System (INIS)

    Demetriou, P.; Keutgen, Th.; Prieels, R.; El Masri, Y.

    2010-01-01

    Fission properties of proton-induced fission on 232 Th, 237 Np, 238 U, 239 Pu, and 241 Am targets, measured at the Louvain-la-Neuve cyclotron facility at proton energies of 26.5 and 62.9 MeV, are compared with the predictions of the state-of-the-art nuclear reaction code talys. The code couples the multimodal random neck-rupture model with the pre-equilibrium exciton and statistical models to predict fission fragment mass yields, pre- and post-scission neutron multiplicities, and total fission cross sections in a consistent approach. The sensitivity of the calculations to the input parameters of the code and possible improvements are discussed in detail.

  8. Nuclear data for neutron emission in the fission process

    International Nuclear Information System (INIS)

    Ganesan, S.

    1991-11-01

    This document contains the proceedings of the IAEA Consultants' Meeting on Nuclear Data for Neutron Emission in the Fission Process, Vienna, 22 - 24 October 1990. Included are the conclusions and recommendations reached at the meeting and the papers presented by the meeting participants. These papers provide a review of the status of experimental and theoretical data on neutron emission in spontaneous and neutron induced fission with reference to the data needs for reactor applications oriented towards actinide burner studies. The specific topics covered are the following: experimental measurements and theoretical predictions and evaluations of fission neutron energy spectra, average prompt fission neutron multiplicity, correlation in neutron emission from complementary fragments, neutron emission during acceleration of fission fragments, statistical properties of neutron rich nuclei by study of emission spectra of neutrons from the excited fission fragments, integral qualification of nu-bar for the major fissile isotopes, nu-bar total of 239 Pu and 235 U, and related problems. Refs figs and tabs

  9. High flux Particle Bed Reactor systems for rapid transmutation of actinides and long lived fission products

    International Nuclear Information System (INIS)

    Powell, J.; Ludewig, H.; Maise, G.; Steinberg, M.; Todosow, M.

    1993-01-01

    An initial assessment of several actinide/LLFP burner concepts based on the Particle Bed Reactor (PBR) is described. The high power density/flux level achievable with the PBR make it an attractive candidate for this application. The PBR based actinide burner concept also possesses a number of safety and economic benefits relative to other reactor based transmutation approaches including a low inventory of radionuclides, and high integrity, coated fuel particles which can withstand extremely high in temperatures while retaining virtually all fission products. In addition the reactor also posesses a number of ''engineered safety features,'' which, along with the use of high temperature capable materials further enhance its safety characteristics

  10. Synthesis of Actinide Materials for the Study of Basic Actinide Science and Rapid Separation of Fission Products

    Energy Technology Data Exchange (ETDEWEB)

    Dorhout, Jacquelyn Marie [Univ. of Nevada, Las Vegas, NV (United States)

    2017-11-28

    This dissertation covers several distinct projects relating to the fields of nuclear forensics and basic actinide science. Post-detonation nuclear forensics, in particular, the study of fission products resulting from a nuclear device to determine device attributes and information, often depends on the comparison of fission products to a library of known ratios. The expansion of this library is imperative as technology advances. Rapid separation of fission products from a target material, without the need to dissolve the target, is an important technique to develop to improve the library and provide a means to develop samples and standards for testing separations. Several materials were studied as a proof-of-concept that fission products can be extracted from a solid target, including microparticulate (< 10 μm diameter) dUO2, porous metal organic frameworks (MOFs) synthesized from depleted uranium (dU), and other organicbased frameworks containing dU. The targets were irradiated with fast neutrons from one of two different neutron sources, contacted with dilute acids to facilitate the separation of fission products, and analyzed via gamma spectroscopy for separation yields. The results indicate that smaller particle sizes of dUO2 in contact with the secondary matrix KBr yield higher separation yields than particles without a secondary matrix. It was also discovered that using 0.1 M HNO3 as a contact acid leads to the dissolution of the target material. Lower concentrations of acid were used for future experiments. In the case of the MOFs, a larger pore size in the framework leads to higher separation yields when contacted with 0.01 M HNO3. Different types of frameworks also yield different results.

  11. Formation of fission-fragment mass distribution for nuclei lighter than thorium

    International Nuclear Information System (INIS)

    Itkis, M.G.; Mul'gin, S.I.; Rusanov, A.Y.; Okolovich, A.N.; Smirenkin, G.N.

    1986-01-01

    A phenomenological approach to description of fission-fragment mass distribution Y(M) for nuclei in the vicinity of Pb is developed and used to extract from the experimental Y(M) data the nuclear deformation potential energy V(M) and its components: the macroscopic (liquid-drop) part and the shell correction in the transition state. The results of the analysis are compared with the theoretically obtained V(M) and Y(M). The three-hump fragment-mass distributions observed in Ra fission are satisfactorily described within the framework of the approach developed. The properties of the symmetric and asymmetric fission valleys and the related Y(M) components are discussed

  12. Measurement of fission cross-section of actinides at n_TOF for advanced nuclear reactors

    CERN Document Server

    Calviani, Marco; Montagnoli, G; Mastinu, P

    2009-01-01

    The subject of this thesis is the determination of high accuracy neutron-induced fission cross-sections of various isotopes - all of which radioactive - of interest for emerging nuclear technologies. The measurements had been performed at the CERN neutron time-of-flight facility n TOF. In particular, in this work, fission cross-sections on 233U, the main fissile isotope of the Th/U fuel cycle, and on the minor actinides 241Am, 243Am and 245Cm have been analyzed. Data on these isotopes are requested for the feasibility study of innovative nuclear systems (ADS and Generation IV reactors) currently being considered for energy production and radioactive waste transmutation. The measurements have been performed with a high performance Fast Ionization Chamber (FIC), in conjunction with an innovative data acquisition system based on Flash-ADCs. The first step in the analysis has been the reconstruction of the digitized signals, in order to extract the information required for the discrimination between fission fragm...

  13. Partitioning and transmutation of actinides and fission products

    International Nuclear Information System (INIS)

    Baetsle, L.H.

    1993-01-01

    The world's nuclear power plants have a total installed capacity of approximately 340 GWe. They give rise to an annual volume of approximately 9000 t of radioactive waste, which is reprocessed, separated from its plutonium content, contained, and stored in repositories to close the nuclear fuel cycle. Direct disposal is being discussed as an alternative to this procedure. As repositories in suitable types of host rock are not operational, the only viable solution is long-term interim storage above ground. If the volumes of radioactive waste are to be reduced, the longlived actinides and fission products must be partitioned. Isotope partitioning in accelerators, though still sounding like science fiction, may soon be indispensable as the third way of treating radioactive waste. The use of mixed oxide fuel in light water reactors and fast breeder reactors both help to limit waste arisings and protect the long-term continuity of raw materials supply. However, both require public acceptance if they are to succeed. (orig.) [de

  14. Theoretical Description of the Fission Process

    International Nuclear Information System (INIS)

    Nazarewicz, Witold

    2009-01-01

    Advanced theoretical methods and high-performance computers may finally unlock the secrets of nuclear fission, a fundamental nuclear decay that is of great relevance to society. In this work, we studied the phenomenon of spontaneous fission using the symmetry-unrestricted nuclear density functional theory (DFT). Our results show that many observed properties of fissioning nuclei can be explained in terms of pathways in multidimensional collective space corresponding to different geometries of fission products. From the calculated collective potential and collective mass, we estimated spontaneous fission half-lives, and good agreement with experimental data was found. We also predicted a new phenomenon of trimodal spontaneous fission for some transfermium isotopes. Our calculations demonstrate that fission barriers of excited superheavy nuclei vary rapidly with particle number, pointing to the importance of shell effects even at large excitation energies. The results are consistent with recent experiments where superheavy elements were created by bombarding an actinide target with 48-calcium; yet even at high excitation energies, sizable fission barriers remained. Not only does this reveal clues about the conditions for creating new elements, it also provides a wider context for understanding other types of fission. Understanding of the fission process is crucial for many areas of science and technology. Fission governs existence of many transuranium elements, including the predicted long-lived superheavy species. In nuclear astrophysics, fission influences the formation of heavy elements on the final stages of the r-process in a very high neutron density environment. Fission applications are numerous. Improved understanding of the fission process will enable scientists to enhance the safety and reliability of the nation's nuclear stockpile and nuclear reactors. The deployment of a fleet of safe and efficient advanced reactors, which will also minimize radiotoxic

  15. Estimates of fission barrier heights for neutron-deficient Po to Ra nuclei produced in fusion reactions

    Directory of Open Access Journals (Sweden)

    Sagaidak Roman

    2017-01-01

    Full Text Available The cross section data for fission and evaporation residue production in fusion reactions leading to nuclei from Po to Ra have been considered in a systematic way in the framework of the conventional barrier-passing (fusion model coupled with the statistical model. The cross section data obtained in very asymmetric projectile-target combinations can be described within these models rather well with the adjusted model parameters. In particular, one can scale and fix the macroscopic (liquid-drop fission barrier heights (FBHs for nuclei involved in the de-excitation of compound nuclei produced in the reactions. The macroscopic FBHs for nuclei from Po to Ra have been derived in the framework of such analysis and compared with the predictions of various theoretical models.

  16. Formation of heavy compound nuclei, their survival and correlation with longtime-scale fission

    International Nuclear Information System (INIS)

    Karamyan, S.A.; Yakushev, A.B.

    2006-01-01

    Fusion of two massive nuclei with formation of super-heavy compound nucleus (CN) is driven by the potential energy gradient, as follows from the analysis of nuclear reaction cross-sections. The conservative energy of the system is deduced in simple approximation using regularized nuclear mass and interaction barrier values. Different reactions for the synthesis of Z c 110-118 nuclei are compared and the favourable conditions are found for fusion of the stable (W-Pt) isotopes with radioactive fission fragment projectiles, like 94 Kr or 100 Sr. Thus, the cold fusion method can be extended for a synthesis of elements with Z > 113. Survival of the evaporation residue is defined by the neutron-to-fission probability ratio and by the successful emission of gammas at the final step of the reaction. Numerical estimates are presented. Fixation of evaporation residue products must correlate with longtime-scale fission and available experimental results are discussed

  17. Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum

    International Nuclear Information System (INIS)

    Bonneau, L.

    2003-11-01

    A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J 2 in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J 2 operator. (A.C.)

  18. Amount, disposal and relative toxicity of long-lived fission products and actinides in the radioactive wastes of the nuclear fuel cycles

    International Nuclear Information System (INIS)

    Haug, H.O.

    1975-11-01

    A review is presented on the magnitude of the long-term problems of radioactive wastes from the nuclear power industry of the FRG (and Western Europe). The production of long-lived fission products and actinides has been calculated for several fuel types of the uranium-plutonium and thorium-uranium fuel cycles and related to a prediction of the development and share of LWR, FBR and HTGR. The quantities and concentrations of actinides, the radioactivity and relative toxicity index of the wastes of reprocessing (and fuel refabrication) and their changes by radioactive decay are presented. The radiotoxicity of the nuclide inventory of the solidified high-level wastes have been compared with naturally occuring uranium ores. On the long term (>10 3 years) the radiotoxicity level of the total area of the final repository in deep geological formation does not result in a significantly higher radiotoxicity level than an uranium ore deposit of low uranium content. Also discussed have been the chemical separation of the actinides from high-level wastes and recycling in fission reactors. (orig.) [de

  19. Masses and fission barriers of nuclei in the LSD model

    Energy Technology Data Exchange (ETDEWEB)

    Pomorski, Krzysztof

    2009-07-01

    Recently developed Lublin-Strasbourg Drop (LSD) model together with the microscopic corrections taken r is very successful in describing many features of nuclei. In addition to the classical liquid drop model the LSD contains the curvature term proportional to the A{sup 1/3}. The r.m.s. deviation of the LSD binding energies of 2766 isotopes with Z,N>7 from the experimental ones is 0.698 MeV only. It turns out that the LSD model gives also a satisfactory prediction of the fission barrier heights. In addition, it was found in that taking into account the deformation dependence of the congruence energy proposed by Myers and Swiatecki significantly approaches the LSD-model barrier-heights to the experimental data in the case of light isotopes while the fission barriers for heavy nuclei remain nearly unchanged and agree well with experiment. It was also shown in that the saddle point masses of transactinides from {sup 232}Th to {sup 250}Cf evaluated using the LSD differ by less than 0.67 MeV from the experimental data.

  20. Transmutation of waste actinides in thermal reactors: survey calculations of candidate irradiation schemes

    International Nuclear Information System (INIS)

    Gorrell, T.C.

    1978-11-01

    Actinide recycle and transmutation calculations were made for twelve specific thermal reactor environments. The calculations included H 2 O-moderated reactor lattices with enriched U, recycled Pu, and 233 ' 235 U-Th. In addition two D 2 O reactor cases were calculated. When all actinides were recycled into 235 U-enriched fuel, about 10 percent of the transuranic actinides were fissioned per 3-year fuel cycle. About 9 percent of the actinides were fissioned per 3-year fuel cycle when waste actinides (no U or Pu) were irradiated in separate target rods in a U-fuel assembly. When actinides were recycled in separate target assemblies, the fission rate was strongly dependent on the specific loading of the target. Fission rates of 5 to 10 percent per 3-year fuel cycle were observed

  1. Neutron emission in fission of highly excited californium nuclei (E* = 76 MeV)

    International Nuclear Information System (INIS)

    Blinov, M.V.; Bordyug, V.M.; Kozulin, E.M.; Levitovich, M.; Mozhaev, A.N.; Muzychka, Yu.A.; Penionzhkevich, Yu.E.; Pustyl'nik, B.I.

    1990-01-01

    Differential cross sections for neutron production have been measured in fission of excited californium nuclei produced in the reaction 238 U + 12 C (105 MeV). It follows from analysis of the experimental results that the number of neutrons emitted before fission considerably exceeds the number obtained in the framework of the standard statistical model. On the basis of the multiplicity of neutrons they authors have estimated the time of fission of the excited nucleus. The dependence of the number of neutrons and their average energies on the mass of the fragments is determined

  2. First inverse-kinematics fission measurements in a gaseous active target

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Tajes, C., E-mail: rodriguez@ganil.fr [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Farget, F. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Acosta, L. [Departamento de Ciencias Integradas, Universidad de Huelva, E-21071 Huelva (Spain); Alvarez-Pol, H. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Babo, M.; Boulay, F. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Caamaño, M. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Damoy, S. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Fernández-Domínguez, B. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Galaviz, D. [Centro de Física Nuclear da Universidade de Lisboa, CFNUL, 1649-003 Lisboa (Portugal); Grinyer, G.F.; Grinyer, J. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Bd. Henri Becquerel, 14076 Caen (France); Harakeh, M.N. [KVI-CART, University of Groningen, Zernikelaan 25, NL-9747 AA Groningen (Netherlands); Konczykowski, P. [Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); and others

    2017-02-15

    The fission of a variety of actinides was induced by fusion and transfer reactions between a {sup 238}U beam and {sup 12}C nuclei, in the active target MAYA. The performance of MAYA was studied, as well as its capability to reconstruct the fission-fragment trajectories. Furthermore, a full characterization of the different transfer reactions was achieved, and the populated excitation-energy distributions were investigated as a function of the kinetic energy in the entrance channel. The ratio between transfer- and fusion-induced fission cross-sections was also determined, in order to investigate the competition between both reaction types and its evolution with the incident energy. The experimental results will be discussed with a view to forthcoming radioactive-ion beam facilities, and next-generation active-target setups.

  3. Fission barriers in the quasi-molecular shape path

    International Nuclear Information System (INIS)

    Royer, G.; Bonilla, C.; Zbiri, K.; Gherghescu, R.A.

    2003-01-01

    New observed phenomena like asymmetric fission of intermediate mass nuclei, nuclear molecules in light nuclei, super and hyperdeformations, cluster radioactivity, fast-fission of heavy systems and fragmentation have renewed interest in investigating the fusion-like fission valley which leads rapidly to two touching spherical fragments and quasi-molecular shapes. Furthermore, rotating super and hyperdeformed nuclear states and superheavy nuclei can be formed only in heavy-ion collisions for which the initial configuration is two close quasi-spherical nuclei. For these shapes the balance between the Coulomb forces and surface tension forces does not allow to link the sheets of the potential energy surface corresponding to one-body shapes and to two separated fragments, respectively. It is necessary to add another term called proximity energy reproducing the finite-range effects of the nuclear force in the neck or the gap between the nascent fission fragments. A generalized liquid drop model has been developed to take into account this nuclear proximity energy, the mass and charge asymmetry, an accurate nuclear radius and the temperature effects. The initial value of the surface energy coefficient has been kept. Microscopic corrections have been determined within the asymmetric two center shell model or simpler algebraic approximations. With this model and deformation valley first studies had led to the following results: (i) good agreement between the potential barrier heights and the experimental fission barrier heights in the whole mass range; (ii) saddle-point corresponding to two separated fragments maintained in unstable equilibrium by the balance between the repulsive Coulomb forces and the attractive proximity forces; (iii) strong enhancement of the maximal angular momentum against fission; (iv) reasonable agreement with experimental data on the double-humped barriers of actinides. Within this same approach we have recently shown that the calculated potential

  4. Fission cross-section measurements on 233U and minor actinides at the CERN n-TOF facility

    International Nuclear Information System (INIS)

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

    2010-01-01

    Neutron-induced fission cross-sections of minor actinides have been measured at the white neutron source n-TOF at CERN, Geneva. The studied isotopes include 233 U, interesting for Th/U based nuclear fuel cycles, 241, 243 Am and 245 Cm, relevant for transmutation and waste reduction studies in new generation fast reactors (Gen-IV) or Accelerator Driven Systems. The measurements take advantage of the unique features of the n-TOF facility, namely the wide energy range, the high instantaneous neutron flux and the low background. Results for the involved isotopes are reported from ∼30 meV to around 1 MeV neutron energy. The measurements have been performed with a dedicated Fission Ionization Chamber (FIC), relative to the standard cross-section of the 235 U fission reaction, measured simultaneously with the same detector. Results are here reported. (authors)

  5. Fission of spin-aligned projectile-like nuclei in the interactions of 29 MeV/nucleon 208Pb with 197Au

    International Nuclear Information System (INIS)

    Bresson, S.; Morjean, M.; Jastrzebski, J.; Skulski, W.; Kordyasz, A.; Lott, B.

    1992-01-01

    Binary fission of projectile-like nuclei was investigated in the interaction of 29 MeV/nucleon Pb on Au, together with the associated neutron multiplicity. Fission is only observed in rather peripheral collisions and represents approximately 20% of the total reaction cross-section. The fission process occurs after collisions in which up to 550 MeV have been dissipated. The angular and energy distribution of the fragments can be accounted for by assuming a noticeable spin alignment of the fissioning nuclei. (author) 18 refs.; 3 figs

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

    International Nuclear Information System (INIS)

    Martin, Julie-Fiona

    2014-01-01

    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: 234 U, 235 U, 237 Np and 238 Np. The experiment is led at the heavy-ion accelerator GSI in Darmstadt, Germany. This facility provides intense relativistic primary beam of 238 U. 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

  7. Analysis of some modes of multibody decays of low excited actinide nuclei

    International Nuclear Information System (INIS)

    Pyatkov, Yu V; Lavrova, J E; Kamanin, D V; Alexandrov, A A; Alexandrova, I A; Goryainova, Z I; Kuznetsova, E A; Strekalovsky, A O; Strekalovsky, O V; Zhuchko, V E; Mkaza, N; Malaza, V

    2017-01-01

    Careful studies of the fission fragments mass correlation distributions let us to reveal specific linear structures in the region of a big missing mass. It became possible due to applying of effective cleaning of this region from the background linked with scattered fragments. One of the most pronounced structure looks like a rectangle bounded by the magic nuclei. The fission events aggregated in the rectangle show a very low total kinetic energy. We propose possible scenario of forming and decay of the multi-cluster prescission configuration decisive for the experimental findings. This approach is valid as well for treating of another rare decay modes discovered in the past. (paper)

  8. β4 systematics in rare-earth and actinide nuclei: sdg interacting boson model description

    International Nuclear Information System (INIS)

    Devi, Y.D.; Kota, V.K.B.

    1992-01-01

    The observed variation of hexadecupole deformation parameter β 4 with mass number A in rare-earth and actinide nuclei is studied in the sdg interacting boson model (IBM) using single j-shell Otsuka-Arima-Iachello mapped and IBM-2 to IBM-1 projected hexadecupole transition operator together with SU sdg (3) and SU sdg (5) coherent states. The SU sdg (3) limit is found to provide a good description of data

  9. Multi-dimensional fission-barrier calculations from Se to the SHE; from the proton to the neutron drip lines

    International Nuclear Information System (INIS)

    Moeller, Peter; Sierk, Arnold J.; Bengtsson, Ragnar; Iwamoto, Akira

    2003-01-01

    We present fission-barrier-height calculations for nuclei throughout the periodic system based on a realistic theoretical model of the multi-dimensional potential-energy surface of a fissioning nucleus. This surface guides the nuclear shape evolution from the ground state, over inner and outer saddle points, to the final configurations of separated fission fragments. We have previously shown that our macroscopic-microscopic nuclear potential-energy model yields calculated 'outer' fission-barrier heights (E B ) for even-even nuclei throughout the periodic system that agree with experimental data to within about 1.0 MeV. We present final results of this work. Just recently we have enhanced our macroscopic-microscopic nuclear potential-energy model to also allow the consideration of axially asymmetric shapes. This shape degree of freedom has a substantial effect on the calculated height (E A ) of the inner peak of some actinide fission barriers. We present examples of fission-barrier calculations by use of this model with its redetermined constants. Finally we discuss what the model now tells us about fission barriers at the end of the r-process nucleosynthesis path. (author)

  10. Induced fission of nuclei: dynamical chaos and lifetime of compound nucleus

    Energy Technology Data Exchange (ETDEWEB)

    Krivoshej, I V

    1987-01-01

    A semi-phenomenological theory is proposed to describe the induced fission of heavy nuclei at low and intermediate excitation energies. The theory is based on the concept of the dynamical chaos, arising because of a negative curvature of the n-dimensional potential energy surface (PES). The nuclear fission is treated as a diffusion of the representing point across a vicinity of the saddle point in PES. The diffusion coefficient is calculated for various metrics in PES as an explicit function of the two-dimensional curvatures at the saddle point of PES. The present theory suggests an estimate for the fission time, tau/sub f/approx.10/sup -14/ s. Coefficients of nuclear friction and viscosity are also calculated in general, and the resulting numerical estimates are in agreement with the experimental data.

  11. Non-compound nucleus fission in actinide and pre-actinide regions

    Indian Academy of Sciences (India)

    2015-07-22

    Jul 22, 2015 ... In this article, some of our recent results on fission fragment/product angular distributions are discussed in the context of non-compound nucleus fission. Measurement of fission fragment angular distribution in 28Si+176Yb reaction did not show a large contribution from the non-compound nucleus fission.

  12. Burning minor actinides in a HTR energy spectrum

    International Nuclear Information System (INIS)

    Pohl, Christoph; Rütten, H. Jochem

    2012-01-01

    Highlights: ► Burn-up analysis for varying plutonium/minor actinide fuel compositions. ► The influence of varying heavy metal fuel element loads is investigated. ► Significant burn-up via radiative capture and subsequently fission is observed. ► Difference observed between fuel element burn-up and total actinide burning rate. - Abstract: The generation of nuclear energy by means of the existing nuclear reactor systems is based mainly on the fission of U-235. But this comes along with the capture of neutrons by the U-238 faction and results in a build-up of plutonium isotopes and minor actinides as neptunium, americium and curium. These actinides are dominant for the long time assessment of the radiological risk of a final disposal therefore a minimization of the long living isotopes is aspired. Burning the actinides in a high temperature helium cooled graphite moderated reactor (HTR) is one of these options. The use of plutonium isotopes to sustain the criticality of the system is intended to avoid on the one hand highly enriched uranium because of international regulations and on the other hand low enriched uranium because of the build up of new actinides from neutron capture in the U-238 fraction. Because initial minor actinide isotopes are typically not fissionable by thermal neutrons the idea is to fission instead the intermediate isotopes generated by the first neutron capture. This paper comprises calculations for plutonium/minor actinides/thorium fuel compositions and their correlated final burn-up for a generic pebble bed HTR based on the reference design of the 400 MW PBMR. In particular the cross sections and the neutron balance of the different minor actinide isotopes in the higher thermal energy spectrum of a HTR will be discussed. For a fuel mixture of plutonium and minor actinides a significant burn-up of these actinides up to 20% can be achieved but at the expense of a higher residual fraction of plutonium in the burned fuel. Combining

  13. Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

    2004-07-01

    There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

  14. Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

    International Nuclear Information System (INIS)

    Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

    2004-01-01

    There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

  15. Generalized Energy-Dependent Q Values for Fission

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, R

    2010-03-31

    We extend Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q value for major and minor actinides on the incident neutron energies in the range 0 {le} E{sub n} {le} 20 MeV. Our parameterization is based on the actinide evaluations recommended for the ENDF/B-VII.1 release. This paper describes the calculation of energydependent fission Q values based on the calculation of the prompt energy release in fission by Madland. This calculation was adopted for use in the LLNL ENDL database and then generalized to obtain the prompt fission energy release for all actinides. Here the calculation is further generalized to the total energy release in fission. There are several stages in a fission event, depending on the time scale. Neutrons and gammas may be emitted at any time during the fission event.While our discussion here is focussed on compound nucleus creation by an incident neutron, similar parameterizations could be obtained for incident gammas or spontaneous fission.

  16. Superdeformed nuclei

    International Nuclear Information System (INIS)

    Janssens, R.V.F.; Khoo, T.L.

    1991-01-01

    Superdeformation was first proposed some twenty years ago to explain the fission isomers observed in some actinide nuclei. It was later realized that superdeformed shapes can occur at high angular momentum in lighter nuclei. The interest in the mechanisms responsible for these exotic shapes has increased enormously with the discovery of a superdeformed band of nineteen discrete lines in 152 Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132 Ce(9). Striking properties emerged from the first experiments, such as the essentially constant energy spacing between transitions (picket-fence spectra), the unexpectedly strong population of superdeformed bands at high spins, and the apparent lack of a link between the superdeformed states and the yrast levels. These findings were reviewed by Nolan and Twin. The present article follows upon their work and discusses the wealth of information that has since become available. This includes the discovery of a new island of superdeformation near A = 190, the detailed spectroscopy of ground and excited bands in the superdeformed well near A = 150 and A = 190, the surprising occurrence of superdeformed bands with identical transition energies in nuclei differing by one or two mass units, and the improved understanding of mechanisms responsible for the feeding into and the decay out of the superdeformed states

  17. Measurements of thermal fission and capture cross sections of minor actinides within the Mini-INCA project

    Energy Technology Data Exchange (ETDEWEB)

    Bringer, O.; Chabod, S.; Dupont, E.; Letourneau, A.; Panebianco, S.; Veyssiere, Ch. [CEA Saclay, Dept. d' Astrophysique de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, 91- Gif sur Yvette (France); Oriol, L. [CEA Cadarache, Dept. d' Etudes des Reacteurs, 13 - Saint Paul lez Durance (France); Chartier, F. [CEA Saclay, Dept. de Physico-Chimie, 91 - Gif sur Yvette (France); Mutti, P. [Institut Laue Langevin, 38 - Grenoble, (France); AlMahamid, I. [Wadsworth Center, New York State Dept. of Health, Albany, NY (United States)

    2008-07-01

    In the framework of nuclear waste transmutation studies, the Mini-INCA project has been initiated at Cea/DSM to determine optimal conditions for transmutation and incineration of Minor Actinides in high intensity neutron fluxes in the thermal region. Our experimental tool is based on alpha- and gamma-spectroscopy of irradiated samples and microscopic fission-chambers. It can provide both microscopic information on nuclear reactions (total and partial cross sections for neutron capture and/or fission reactions) and macroscopic information on transmutation and incineration potentials. The {sup 232}Th, {sup 237}Np, {sup 241}Am, and {sup 244}Cm transmutation chains have been explored in details, showing some discrepancies in comparison with evaluated data libraries but in overall good agreement with recent experimental data. (authors)

  18. Measurements of thermal fission and capture cross sections of minor actinides within the Mini-INCA project

    International Nuclear Information System (INIS)

    Bringer, O.; Chabod, S.; Dupont, E.; Letourneau, A.; Panebianco, S.; Veyssiere, Ch.; Oriol, L.; Chartier, F.; Mutti, P.; AlMahamid, I.

    2008-01-01

    In the framework of nuclear waste transmutation studies, the Mini-INCA project has been initiated at Cea/DSM to determine optimal conditions for transmutation and incineration of Minor Actinides in high intensity neutron fluxes in the thermal region. Our experimental tool is based on alpha- and gamma-spectroscopy of irradiated samples and microscopic fission-chambers. It can provide both microscopic information on nuclear reactions (total and partial cross sections for neutron capture and/or fission reactions) and macroscopic information on transmutation and incineration potentials. The 232 Th, 237 Np, 241 Am, and 244 Cm transmutation chains have been explored in details, showing some discrepancies in comparison with evaluated data libraries but in overall good agreement with recent experimental data. (authors)

  19. Actinides integral measurements on FCA assemblies

    International Nuclear Information System (INIS)

    Mukaiyama, Takehiko; Okajima, Shigeaki

    1984-01-01

    Actinide integral measurements were performed on eight assemblies of FCA where neutron energy spectra were shifted systematically from soft to hard in order to evaluate and modify the nuclear cross section data of major actinides. Experimental values on actinide fission rates and sample reactivity worths are compared with the calculated values using JENDL-2 and ENDF/B-V (or IV) data sets. (author)

  20. Strongly Enhanced Low Energy Alpha-Particle Decay in Heavy Actinide Nuclei and Long-Lived Superdeformed and Hyperdeformed Isomeric States

    CERN Document Server

    Marinov, Amnon; Kolb, D.; Weil, J.L.

    2001-01-01

    Relatively low energy and very enhanced alpha-particle groups have been observed in various actinide fractions produced via secondary reactions in a CERN W target which had been irradiated with 24-GeV protons. In particular, 5.14, 5.27 and 5.53 MeV alpha-particle groups with corresponding half-lives of 3.8(+ -)1.0 y, 625(+ -)84 d and 26(+ -)7 d, have been seen in Bk, Es and Lr-No sources, respectively. The measured energies are a few MeV lower than the known g.s. to g.s. alpha-decays in the corresponding neutron-deficient actinide nuclei. The half-lives are 4 to 7 orders of magnitude shorter than expected from the systematics of alpha-particle decay in this region of nuclei. The deduced evaporation residue cross sections are in the mb region, about 4 orders of magnitude higher than expected. A consistent interpretation of the data is given in terms of production of long-lived isomeric states in the second and third wells of the potential-energy surfaces of the parent nuclei, which decay to the corresponding w...

  1. Microscopic mechanism of moments of inertia and odd-even differences for well-deformed actinide nuclei

    International Nuclear Information System (INIS)

    Yu Lei; Liu Shuxin; Zeng Jinyan

    2004-01-01

    The microscopic mechanism of the variation with rotational frequency of moments of inertia and their odd-even differences for well-deformed actinide nuclei are analyzed by using the particle-number conserving (PNC) method for treating nuclear pairing interaction. The moments of inertia for bands building on high j intruder orbitals in odd-A nuclei, e.g., the 235 U (ν[743]7/2) band, are found to be much larger than those of ground-state bands in neighboring even-even nuclei. Moreover, there exist large odd-even differences in the ω variation of moments of inertia. All these experimental odd-even differences are reproduced quite well in the PNC calculation, in which the effective monopole and quadrupole pairing interaction strengths are determined by the experimental odd-even differences in binding energies and bandhead moments of inertia, and no free parameter is involved in the PNC calculation

  2. Excitation energy dependence of fragment-mass distributions from fission of 180,190Hg formed in fusion reactions of 36Ar + 144,154Sm

    Directory of Open Access Journals (Sweden)

    K. Nishio

    2015-09-01

    Full Text Available Mass distributions of fission fragments from the compound nuclei 180Hg and 190Hg formed in fusion reactions 36Ar + 144Sm and 36Ar + 154Sm, respectively, were measured at initial excitation energies of E⁎(Hg180=33–66 MeV and E⁎(Hg190=48–71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses A¯L/A¯H=79/101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β+/EC-delayed fission of 180Tl, from our earlier ISOLDE(CERN experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of A¯L/A¯H=83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.

  3. Transmutations of nuclear waste. Progress report RAS programme 1995: Recycling and transmutation of actinides and fission products

    International Nuclear Information System (INIS)

    Gruppelaar, H.; Cordfunke, E.H.P.; Konings, R.J.M.; Bultman, J.H.; Dodd, D.H.; Franken, W.M.P.; Kloosterman, J.L.; Koning, A.J.; Wichers, V.A.

    1996-04-01

    This report describes the progress of the Dutch RAS programme on 'Recycling and Transmutation of Actinides and Fission Products' over the year 1995, which is the second year of the 4-year programme 1994-1997. An extensive listing of reports and publications from 1991 to 1995 is given. Highlights in 1995 were: -The completion of the European Strategy Study on Nuclear Waste Transmutation as a result of which the understanding of transmutation of plutonium, minor actinides and long-lived fission products in thermal and fast reactors has been increased significantly. Important ECN contributions were given on Am, 99 Tc and 129 I transmutation options. Follow-up contracts have been obtained for the study of 100% MOX cores and accelerator-based transmutation. - Important progress in the evaluation of CANDU reactors for burning very large amounts of transuranium mixtures in inert matrices. - The first RAS irradiation experiment in the HFR, in which the transmutation of technetium and iodine was examined, has been completed and post-irradiation examination has been started. - A joint proposal of the EFTTRA cooperation for the 4 th Framework Programme of the EU, to demonstrate the feasibility of the transmutation of americium in an inert matrix by an irradiation in the HFR, has been granted. - A bilateral contract with CEA has been signed to participate in the CAPRA programme, and the work in this field has been started. - The thesis work on Actinide Transmutation in Nuclear Reactor Systems was succesfully defended. New PhD studies on Pu burning in HTGR, on nuclear data for accelerator-based systems, and on the SLM-technique for separation of actinides were started. - A review study of the use of the thorium cycle as a means for nuclear waste reduction, has been completed. A follow-up of this work is embedded in an international project for the 4th Framework Programme of the EU. (orig./DG)

  4. Fusion barrier characteristics of actinides

    Science.gov (United States)

    Manjunatha, H. C.; Sridhar, K. N.

    2018-03-01

    We have studied fusion barrier characteristics of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations. After the calculation of fusion barrier heights and positions, we have searched for their parameterization. We have achieved the empirical formula for fusion barrier heights (VB), positions (RB), curvature of the inverted parabola (ħω) of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations (6 projectile target combinations. The values produced by the present formula are also compared with experiments. The present pocket formula produces fusion barrier characteristics of actinides with the simple inputs of mass number (A) and atomic number (Z) of projectile-targets.

  5. Simulation of neutron rich nuclei production through 239U fission at intermediates energies

    International Nuclear Information System (INIS)

    Mirea, M.; Clapier, F.; Pauwels, N.; Proust, J.

    1997-01-01

    The theoretical part and some results obtained from a model realised for fission processes in wide range of mass-asymmetries are presented. The fission barriers are computed in a tridimensional configuration space using the Yukawa - plus - exponential macroscopic energies corrected within the Strutinsky procedure. It is assumed that channel probabilities are proportional with Gamow penetrabilities. The model is applied for the disintegration of the 239 U in order to determine the relative yields for the production of neutron rich nuclei at diverse intermediate energies. (author)

  6. Fission and nuclear fragmentation of silver and bromine nuclei by photons of 1-6 GeV

    International Nuclear Information System (INIS)

    Pinheiro Filho, J.D.

    1983-01-01

    The studies of fission and fragmentation of silver and bromine nuclei by Bremsstrahlung photons of 1.6 GeV energy range are presented. The Il ford-KO nuclear emulsion submitted to Bremsstrahlung beams in Deutsches Elektronen Synchrotron (DESY) with total doses of 10'' equivalent photons, was used for nuclear fragment detection. The discrimination of fission and fragmentation events was done analysing angular distribution, range and angles between fragments. The results of fragment range distributions, angular distributions, distributions of angles between fragments, distributions of ratio between range, velocity distributions forward/backward ratio, cross sections of fission and fragmentation, nuclear fissionability and ternary fission frequency are presented and discussed. (M.C.K.)

  7. Actinide cross section data and inertial confinement fusion for long term waste disposal

    International Nuclear Information System (INIS)

    Meldner, H.

    1979-01-01

    Actinide cross section data at thermonuclear neutron energies are needed for the calculation of ICF pellet center burnup of fission reactor waste, viz. 14 MeV neutron fission of the very long-lived actinides that pose storage problems. A major advantage of pellet center burnup is safety: only milligrams of highly toxic and active material need to be present in the fusion chamber, whereas blanket burnup requires the continued presence of tons of actinides in a small volume. The actinide data tables required for Monte Carlo calculations of the burnup of 241 Am and 243 Am are discussed in connection with typical burnup reactor fusion and fission spectra. 2 figures

  8. Optimization of the recoil-shadow projection method for the investigation of short-lived fission isomers

    Energy Technology Data Exchange (ETDEWEB)

    Helmecke, M.; Thirolf, P.G.; Habs, D.; Gartzke, E.; Kolhinen, V.; Lang, C.; Szerypo, J.; Trepl, L. [Fakultaet f. Physik, LMU Muenchen (Germany); Maier-Leibnitz Laboratory, Garching (Germany)

    2009-07-01

    Spectroscopic studies of super- and hyperdeformed actinide nuclei offer the possibility to gain insight into the multiple-humped fission barrier landscape. With the identification of deep third minima in {sup 234}U and {sup 236}U the systematics of fission isomers in light actinides was revisited, especially searching for isomers in light uranium isotopes with half-lives in the pico-second range. Using the recoil-shadow projection method and solid state nuclear track detectors, an experimental search for their observation has been started. This well-established detection technique nowadays benefits from an efficient analysis technology based on a PC-controlled auto-focus microscope and a CCD camera together with pattern recognition software. The flatness and the definition of the shadow edge of the target is the critical point of this method: Due to the energy loss of the beam the target carrier foil (1{mu}m Ni) may develop thermal distortions in the {mu}m range, leading to misinterpretations of isomeric fission fragments. Therefore the flatness of the target foil is continuously monitored via a capacitance measurement. First results applying this method to the search of a fission isomer in {sup 234}U via the {sup 232}Th({alpha},2n) reaction are presented.

  9. Neutron emission in fission of highly excited californium nuclei (E*=76 MeV)

    International Nuclear Information System (INIS)

    Blinov, M.V.; Bordyug, V.M.; Kozulin, Eh.M.; Mozhaev, A.N.; Levitovich, M.; Muzychka, Yu.A.; Penionzhkevich, Yu.Eh.; Pustyl'nik, B.I.

    1990-01-01

    The differential cross sections for neutron production in the fission of highly excited californium nuclei formed in the 238 U+ 12 C (105 MeV) reaction have been measured. From the analysis of the experimental data is follows that the number of pre-fission neutrons substantially exceeds the value obtained in the framework of the standard statistical model. The saddle-to-scission time of the excited nucleus is estimated on the basis of the neutron multiplicity. The dependences of the neutron number and neutron average energies upon the fragment mass are determined

  10. Experimental approach to fission process of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Hiroshi [Osaka Univ., Toyonaka (Japan). Faculty of Science

    1997-07-01

    From experimental views, it seems likely that the mechanism of nuclear fission process remains unsolved even after the Bohr and Weeler`s study in 1939. Especially, it is marked in respect of mass distribution in unsymmetric nuclear fission. The energy dependency of mass distribution can be explained with an assumption of 2-mode nuclear fission. Further, it was demonstrated that the symmetrical fission components and the unsymmetrical ones have different saddle and fission points. Thus, the presence of the 2-mode fission mechanism was confirmed. Here, transition in the nuclear fission mechanism and its cause were investigated here. As the cause of such transition, plausible four causes; a contribution of multiple-chance fission, disappearance of shell effects, beginning of fission following collective excitation due to GDR and nuclear phase transition were examined in the condition of excitation energy of 14.0 MeV. And it was suggested that the transition in the nuclear fission concerned might be related to phase transition. In addition, the mechanism of nuclear fission at a low energy and multi-mode hypothesis were examined by determination of the energy for thermal neutron fission ({sup 233,235}U and {sup 239}Pu) and spontaneous nuclear fission ({sup 252}Cf). (M.N.)

  11. Selective extraction of actinides from high level liquid wastes. Study of the possibilities offered by the Redox properties of actinides

    International Nuclear Information System (INIS)

    Adnet, J.M.

    1991-07-01

    Partitioning of high level liquid wastes coming from nuclear fuel reprocessing by the PUREX process, consists in the elimination of minor actinides (Np, Am, and traces of Pu and U). Among the possible processes, the selective extraction of actinides with oxidation states higher than three is studied. First part of this work deals with a preliminary step; the elimination of the ruthenium from fission products solutions using the electrovolatilization of the RuO4 compound. The second part of this work concerns the complexation and oxidation reactions of the elements U, Np, Pu and Am in presence of a compound belonging to the insaturated polyanions family: the potassium phosphotungstate. For actinide ions with oxidation state (IV) complexed with phosphotungstate anion the extraction mechanism by dioctylamine was studied and the use of a chromatographic extraction technic permitted successful separations between tetravalents actinides and trivalents actinides. Finally, in accordance with the obtained results, the basis of a separation scheme for the management of fission products solutions is proposed

  12. Fissility of actinide nuclei induced by 60-130 MeV photons

    International Nuclear Information System (INIS)

    Morcelle, Viviane; Tavares, Odilon A.P.

    2004-06-01

    Nuclear fissilities obtained from recent photofission reaction cross section measurements carried out at Saskatchewan Accelerator Laboratory (Saskatoon, Canada) in the energy range 60-130 MeV for 232 Th, 233 U, 235 U, 238 U, and 237 Np nuclei have been analysed in a systematic way. To this aim, a semiempirical approach has been developed based on the quasi-deuteron nuclear photoabsorption model followed by the process of competition between neutron evaporation and fission for the excited nucleus. The study reproduces satisfactorily well the increasing trend of nuclear fissility with parameter Z 2 =A. (author)

  13. Evaluation of actinide partitioning and transmutation

    International Nuclear Information System (INIS)

    1982-01-01

    After a few centuries of radioactive decay the long-lived actinides, the elements of atomic numbers 89-103, may constitute the main potential radiological health hazard in nuclear wastes. This is because all but a very few fission products (principally technetium-99 and iodine-129) have by then undergone radioactive decay to insignificant levels, leaving the actinides as the principal radionuclides remaining. It was therefore at first sight an attractive concept to recycle the actinides to nuclear reactors, so as to eliminate them by nuclear fission. Thus, investigations of the feasibility and potential benefits and hazards of the concept of 'actinide partitioning and transmutation' were started in numerous countries in the mid-1970s. This final report summarizes the results and conclusions of technical studies performed in connection with a four-year IAEA Co-ordinated Research Programme, started in 1976, on the ''Environmental Evaluation and Hazard Assessment of the Separation of Actinides from Nuclear Wastes followed by either Transmutation or Separate Disposal''. Although many related studies are still continuing, e.g. on waste disposal, long-term safety assessments, and waste actinide management (particularly for low and intermediate-level wastes), some firm conclusions on the overall concept were drawn by the programme participants, which are reflected in this report

  14. On-line nuclear half life and spectroscopic measurements on mass-separated fission product nuclei

    International Nuclear Information System (INIS)

    McDonald, J.; Fogelberg, B.; Baecklin, A.

    1979-01-01

    A description is given of the methods and equipment employed for nuclear spectroscopy studies of short lived fission product nuclei at the OSIRIS ISOL facility in Studsvik, Sweden. Furthermore a table of new nuclear half-lives measured with this equipment is presented. (author)

  15. Microbial Transformations of Actinides and Fission Products in Radioactive Waste

    Energy Technology Data Exchange (ETDEWEB)

    Francis, A. J. [Pohang Univ. Science and Technology, Pohang (Korea, Republic of)

    2011-07-01

    The environmental factors that can affect microbial growth and activity include moisture, temperature, ph, Eh, availability of organic and inorganic nutrients, and radiation. The microbial activity in a specific repository is influenced by the ambient environment of the repository, and the materials to be emplaced. For example, a repository in unsaturated igneous rock formations such as volcanic tuff rocks at Yucca Mountain is generally expected to be oxidizing; a repository in a hydrologically expected to be oxidizing; a repository in a hydrologically saturated zone, especially in sedimentary rocks, could be reducing. Sedimentary rocks contain a certain amount of organic matter, which may stimulate microbial activities and, thus maintain the repository and its surrounding areas at reducing conditions. Although the impacts of microbial activity on high-level nuclear waste and the long-term performance of the repository have not fully investigated, little microbial activity is expected in the near-field because of the radiation, lack of nutrients and the harsh conditions. However in the far-field microbial effects could be significant. Much of our understanding of the microbial effects on radionuclides stems from studies conducted with selected transuranic elements and fission products and limited studies with low-level radioactive wastes. Significant aerobic- and anaerobic-microbial activity is expected to occur in the waste because of the presence of electron donors and acceptors. The actinides initially may be present as soluble- or insoluble-forms but, after disposal, may be converted from one to the other by microorganisms. The direct enzymatic or indirect non-enzymatic actions of microbes could alter the speciation, solubility, and sorption properties of the actinides, thereby increasing or decreasing their concentrations in solution.

  16. A new set of parameters for 5 Gaussian fission yields systematics

    International Nuclear Information System (INIS)

    Katakura, Jun-ichi

    2003-01-01

    A new set of parameters for 5 Gaussian-type fission yields systematics has been proposed for applying to high energy neutron or proton fission and to various kinds of fissioning systems including minor actinides. The mass yields calculated using the systematics were compared with various kinds of measured data including the fission with incident energy higher than 100 MeV and the fission of minor actinide nuclides. The comparisons showed rather good agreement between the calculated values and measured ones for various kinds of fissioning systems. (author)

  17. Feasibility studies of actinide recycle in LMFBRs as a waste management alternative

    International Nuclear Information System (INIS)

    Beaman, S.L.; Aitken, E.A.

    1976-01-01

    A strategy of actinide burnup in LMFBRs is being investigated as a waste management alternative to long term storage of high level nuclear waste. This strategy is being evaluated because many of the actinides in the waste from spent-fuel reprocessing have half-lives of thousands of years and an alternative to geological storage may be desired. From a radiological viewpoint, the actinides and their daughters dominate the waste hazard for decay times beyond about 400 years. Actinide burnup in LMFBRs may be an attractive alternative to geological storage because the actinides can be effectively transmuted to fission products which have significantly shorter half-lives. Actinide burnup in LMFBRs rather than LWRs is preferred because the ratio of fission reaction rate to capture reaction rate for the actinides is higher in an LMFBR, and an LMFBR is not so sensitive to the addition of the actinide isotopes. An actinide target assembly recycle scheme is evaluated to determine the effects of the actinides on the LMFBR performance, including local power peaking, breeding ratio, and fissile material requirements. Several schemes are evaluated to identify any major problems associated with reprocessing and fabrication of recycle actinide-containing assemblies. The overall efficiency of actinide burnout in LMFBRs is evaluated, and equilibrium cycle conditions are determined. It is concluded that actinide recycle in LMFBRs offers an attractive alternative to long term storage of the actinides, and does not significantly affect the performance of the host LMFBR. Assuming a 0.1 percent or less actinide loss during reprocessing, a 0.1 percent loss of less during fabrication, and proper recycle schemes, virtually all of the actinides produced by a fission reactor economy could be transmuted in fast reactors

  18. Geochemistry of long lived transuranic actinides and fission products

    International Nuclear Information System (INIS)

    1992-01-01

    The IAEA initiated in 1987 a new Co-ordinated Research Programme (CRP) on geochemistry of long lived transuranic actinides and fission products for a duration of 5 years. The framework of the CRP consists of three main components: (1) development of a working hypothesis with focus on laboratory studies; (2) testing of the working hypothesis with the focus on the field studies; and (3) transport modelling. The contents of this document reflect the results reported on by a number of Member States who participated in this Co-ordinated Research Programme which investigated the geochemical processes and mechanisms which affect rock-water interactions and migration of the chemical elements in geological media as scientific background in support of safety assessments of repositories for high level radioactive wastes. Studies conducted considered the migration of the long lived radionuclides of Tc, I, Np and Pu in both the near and far field. The programme investigated natural occurrences and geochemical processes and mechanisms which may affect migration of the chemical elements under consideration in geological media which may be used for disposal of radioactive wastes. 47 refs, 9 figs, 1 tab

  19. Cross section of ternary fission of Al, Ti, Co and Zr nuclei induced by 0,8 - 1,8 Gev photons

    International Nuclear Information System (INIS)

    Lima, D.A. de; Sousa, E.V. de; Milomen, W.C.C.; Tavares, O.A.P.

    1988-01-01

    A research on ternary fission of Al, Ti, Co, and Zr nuclei induced by bremsstrahlung photons of 0,8, 1,0, 1,4, and 1,8 Gev end-point energies has been carried out using makrofol polycarbonate and CR-39 polymer as fission-track detectors. Results are discussed and compared with other ternary fission data. (M.W.O.) [pt

  20. Fission level densities

    International Nuclear Information System (INIS)

    Maslov, V.M.

    1998-01-01

    Fission level densities (or fissioning nucleus level densities at fission saddle deformations) are required for statistical model calculations of actinide fission cross sections. Back-shifted Fermi-Gas Model, Constant Temperature Model and Generalized Superfluid Model (GSM) are widely used for the description of level densities at stable deformations. These models provide approximately identical level density description at excitations close to the neutron binding energy. It is at low excitation energies that they are discrepant, while this energy region is crucial for fission cross section calculations. A drawback of back-shifted Fermi gas model and traditional constant temperature model approaches is that it is difficult to include in a consistent way pair correlations, collective effects and shell effects. Pair, shell and collective properties of nucleus do not reduce just to the renormalization of level density parameter a, but influence the energy dependence of level densities. These effects turn out to be important because they seem to depend upon deformation of either equilibrium or saddle-point. These effects are easily introduced within GSM approach. Fission barriers are another key ingredients involved in the fission cross section calculations. Fission level density and barrier parameters are strongly interdependent. This is the reason for including fission barrier parameters along with the fission level densities in the Starter File. The recommended file is maslov.dat - fission barrier parameters. Recent version of actinide fission barrier data obtained in Obninsk (obninsk.dat) should only be considered as a guide for selection of initial parameters. These data are included in the Starter File, together with the fission barrier parameters recommended by CNDC (beijing.dat), for completeness. (author)

  1. Special actinide nuclides: Fuel or waste?

    International Nuclear Information System (INIS)

    Srinivasan, M.; Rao, K.S.; Dingankar, M.V.

    1989-01-01

    The special actinide nuclides such as Np, Cm, etc. which are produced as byproducts during the operation of fission reactors are presently looked upon as 'nuclear waste' and are proposed to be disposed of as part of high level waste in deep geological repositories. The potential hazard posed to future generations over periods of thousands of years by these long lived nuclides has been a persistent source of concern to critics of nuclear power. However, the authors have recently shown that each and every one of the special actinide nuclides is a better nuclear fuel than the isotopes of plutonium. This finding suggests that one does not have to resort to exotic neutron sources for transmuting/incinerating them as proposed by some researchers. Recovery of the special actinide elements from the waste stream and recycling them back into conventional fission reactors would eliminate one of the stigmas attached to nuclear energy

  2. Evidence for different fission behavior of hot nuclei formed in central and peripheral collisions of 40Ar + 209Bi reaction at 25 MeV/u

    International Nuclear Information System (INIS)

    Wu Enjiu; Zheng Jiwen; Xiao Zhigang; Zhang Chun; Tan Jilian; Yin Shuzhi; Wang Sufang; Jin Genming; Yin Xu; Song Mingtao; Jin Weiyang; Peng Xingping; Li Zuyu; Wu Heyu; He Zhiyong; Jiang Dongxing; Qian Xing

    1999-01-01

    Correlated fission fragments from the reaction of 25 MeV/u 40 Ar + 209 Bi and their further correlation with α particles have been studied for peripheral and central collisions simultaneously. The excitation energy at scission deduced from post scission multiplicity is about 172.5 MeV. The fission timescale deduced from prescission multiplicity is about 4 x 10 -21 s. Systematic analysis of the mass and energy distributions of fission fragments as a function of the initial temperature of hot fissioning nuclei reveals the existence of different fission behavior of hot nuclei formed in central and peripheral collisions. Experimental data demonstrate the change of fission behavior at T∼4 MeV

  3. Fission of intermediate mass nuclei by bremsstrahlung photons in the energy range 0.8-1.8 GeV

    International Nuclear Information System (INIS)

    Lima, D.A. de.

    1983-01-01

    The fission of intermediate mass nuclei in the Al-Ta internal induced by bremsstrahlung photons of maximum energies between 0,8 to 1,8 GeV is studied. Thin targets of Nd and Sm and dense targets of Al,Ti,Co,Zr,Nb,Ag,In and Ta are utilized, and all the aspects related with the fission fragment absorption by the targets themselves are considered. The samples are exposed in th 2,5 GeV Electron Synchrotron at Bonn University. Muscovite mica, CR-39 and makrofol are used as fission fragments detectors. Fission cross sections and nuclear fissionabilities of the studied elements are estimated. (L.C.) [pt

  4. Fission dynamics of hot nuclei

    Indian Academy of Sciences (India)

    2014-04-05

    Apr 5, 2014 ... across the fission barrier is very small or in other words, the fission barrier is much ... of this shape evolution, the gross features of the fissioning nucleus can be described ..... [7] Y Abe, C Gregoire and H Delagrange, J. Phys.

  5. TMI-2 decay power: LASL fission-product and actinide decay power calculations for the President's Commission at Three Mile Island

    International Nuclear Information System (INIS)

    England, T.R.; Wilson, W.B.

    1979-10-01

    Fission-product and actinide decay heating, gas content, curies, and detailed contributions of the most important nuclide contributors were supplied in a series of letters following requests from the Presidential Commission on the Accident at Three Mile Island. In addition, similar data assuming different irradiation (power) histories were requested for purposes of comparison. This report consolidates the tabular and graphical data supplied and explains its basis

  6. The reduced transition probabilities for excited states of rare-earths and actinide even-even nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ghumman, S. S. [Department of Physics, Sant Longowal Institute of Engineering and Technology (Deemed University), Longowal, Sangrur-148106, Punjab, India s-ghumman@yahoo.com (India)

    2015-08-28

    The theoretical B(E2) ratios have been calculated on DF, DR and Krutov models. A simple method based on the work of Arima and Iachello is used to calculate the reduced transition probabilities within SU(3) limit of IBA-I framework. The reduced E2 transition probabilities from second excited states of rare-earths and actinide even–even nuclei calculated from experimental energies and intensities from recent data, have been found to compare better with those calculated on the Krutov model and the SU(3) limit of IBA than the DR and DF models.

  7. Integrity of chromatin and replicating DNA in nuclei released from fission yeast by semi-automated grinding in liquid nitrogen

    Science.gov (United States)

    2011-01-01

    Background Studies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei. Findings Here we present a useful method for nuclear isolation from the important model organism, the fission yeast, Schizosaccharomyces pombe. To preserve in vivo molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates. Conclusions We have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls. PMID:22088094

  8. Integrity of chromatin and replicating DNA in nuclei released from fission yeast by semi-automated grinding in liquid nitrogen.

    Science.gov (United States)

    Givens, Robert M; Mesner, Larry D; Hamlin, Joyce L; Buck, Michael J; Huberman, Joel A

    2011-11-16

    Studies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei. Here we present a useful method for nuclear isolation from the important model organism, the fission yeast, Schizosaccharomyces pombe. To preserve in vivo molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates. We have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls.

  9. Integrity of chromatin and replicating DNA in nuclei released from fission yeast by semi-automated grinding in liquid nitrogen

    Directory of Open Access Journals (Sweden)

    Givens Robert M

    2011-11-01

    Full Text Available Abstract Background Studies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei. Findings Here we present a useful method for nuclear isolation from the important model organism, the fission yeast, Schizosaccharomyces pombe. To preserve in vivo molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates. Conclusions We have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls.

  10. Modelisation of the fission cross section

    International Nuclear Information System (INIS)

    Morariu, Claudia

    2013-03-01

    The neutron cross sections of four nuclear systems (n+ 235 U, n+ 233 U, n+ 241 Am and n+ 237 Np) are studied in the present document. The target nuclei of the first case, like 235 U and 239 Pu, have a large fission cross section after the absorption of thermal neutrons. These nuclei are called 'fissile' nuclei. The other type of nuclei, like 237 Np and 241 Am, 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) [fr

  11. Stability and production of superheavy nuclei

    International Nuclear Information System (INIS)

    Moeller, P.; Los Alamos National Lab., NM; Nix, J.R.

    1997-01-01

    Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number Z increases, because of the disruptive effect of the long-range Coulomb force. However, in the region just beyond Z = 100 magic proton and neutron numbers and the associated shell structure enhances nuclear stability sufficient to allow observation of additional nuclei. Some thirty years ago it was speculated that an island of spherical, relatively stable superheavy nuclei would exist near the next doubly magic proton-neutron combination beyond 208 Pb, that is, at proton number Z 114 and neutron number N = 184. Theory and experiment now show that there also exists a rock of stability in the vicinity of Z = 110 and N = 162 between the actinide region, which previously was the end of the peninsula of known elements, and the predicted island of spherical superheavy nuclei slightly southwest of the magic numbers Z = 114 and N = 184. The authors review here the stability properties of the heavy region of nuclei. Just as the decay properties of nuclei in the heavy region depend strongly on shell structure, this structure also dramatically affects the fusion entrance channel. The six most recently discovered new elements were all formed in cold-fusion reactions. They discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation

  12. Burning actinides in very hard spectrum reactors

    International Nuclear Information System (INIS)

    Robinson, A.H.; Shirley, G.W.; Prichard, A.W.; Trapp, T.J.

    1978-01-01

    The major unresolved problem in the nuclear industry is the ultimate disposition of the waste products of light water reactors. The study demonstrates the feasibility of designing a very hard spectrum actinide burner reactor (ABR). A 1100 MW/sub t/ ABR design fueled entirely with actinides reprocessed from light water reactor (LWR) wastes is proposed as both an ultimate disposal mechanism for actinides and a means of concurrently producing usable power. Actinides from discharged ABR fuel are recycled to the ABR while fission products are routed to a permanent repository. As an integral part of a large energy park, each such ABR would dispose of the waste actinides from 2 LWRs

  13. Method of measurement of cross sections of heavy nuclei fission induced by intermediate energy protons

    International Nuclear Information System (INIS)

    Kotov, Alexander; Chtchetkovski, Alexander; Fedorov, Oleg; Gavrikov, Yuri; Chestnov, Yuri; Poliakov, Vladimir; Vaishnene, Larissa; Vovchenko, Vil; Fukahori, Tokio

    2003-01-01

    The purpose of this work is experimental studies of the energy dependence of the fission cross sections of heavy nuclei, nat Pb, 209 Bi, 232 Th, 233 U, 235 U, 238 U, 237 Np and 239 Pu, by protons at the energies from 200 to 1000 MeV. At present experiment the method based on use of the gas parallel plate avalanche counters (PPACs) for registration of complementary fission fragments in coincidence and the telescope of scintillation counters for direct counting of the incident protons on the target has been used. First preliminary results of the energy dependences of proton induced fission cross sections for nat Pb, 209 Bi, 235 U and 238 U are reported. (author)

  14. Actinide, Elemental, and Fission Product Measurements by ICPMS at the Savannah River Site

    International Nuclear Information System (INIS)

    Tovo, L.L.; Waller, P.R.; Clymire, J.; Jones, V.D.; Boyce, W.T.

    1998-03-01

    VG Elemental Inductively coupled plasma-mass spectrometer (ICPMS), PlasmaQuad 1 (PQ1) Model No. 4, installed in a radiohood, is used by the Savannah River Technology Center to provide non-routine mass measurements for environmental monitoring, waste tank characterization studies, isotope ratios for criticality determinations, and the measurement of elemental, fission product, and actinide mass distributions of the glass product from the Defense Waste Processing Facility (DWPF). Modifications to improve instrument reliability, sample preparation, and data handling, as well as modifications to the laboratory that permit measurements in a radioactive environment will be discussed. Based on our operating experience, two laboratory facilities are being prepared for additional instruments to operate in a radioactive environment. A separate instrument is being installed for non-radioactive measurements and method development

  15. Fission of {sup 209}Bi and {sup 197}Au nuclei induced by 30 MeV protons

    Energy Technology Data Exchange (ETDEWEB)

    Noshad, Houshyar; Soheyli, Saeed [Amir-Kabir University of Technology, Physics and Nuclear Science Department, Tehran (Iran); Lamehi-Rachti, Mohammad [Atomic Energy Organization of Iran (AEOI), Nuclear Research Center, Van de Graaff Laboratory, Tehran (Iran)

    2001-10-01

    Thin targets of {sup 209}Bi and {sup 197}Au were bombarded with 30 MeV protons at the Cyclotron Department of Nuclear Research Center for Agriculture and Medicine (NRCAM). Correlated measurements of kinetic energies of fission fragment pairs, and their time-of-flights were made using pair spectrometry. The fission cross sections, fragment mass distributions, and total kinetic energy distributions of the fragments were measured in our experiment. The accurate values of cross sections for fission of {sup 209}Bi and {sup 197}Au nuclei with 30 MeV protons were obtained to be 1,100{+-}100 and 62{+-}5.6 {mu}b, respectively. The cross section of {sup 209}Bi fission with its associated error, through using this method, has not been reported previously. The interpretation in terms of liquid-drop model of fissioning nucleus {sup 210}Po at the excitation energy of 35 MeV was confirmed by the dispersion of the distribution in fragment mass for bismuth fission. (author)

  16. Partition of actinides and fission products between metal and molten salt phases: Theory, measurement, and application to IFR pyroprocess development

    International Nuclear Information System (INIS)

    Ackerman, J.P.; Johnson, T.R.

    1993-01-01

    The chemical basis of Integral Fast Reactor fuel reprocessing (pyroprocessing) is partition of fuel, cladding, and fission product elements between molten LiCl-KCl and either a solid metal phase or a liquid cadmium phase. The partition reactions are described herein, and the thermodynamic basis for predicting distributions of actinides and fission products in the pyroprocess is discussed. The critical role of metal-phase activity coefficients, especially those of rare earth and the transuranic elements, is described. Measured separation factors, which are analogous to equilibrium constants but which involve concentrations rather than activities, are presented. The uses of thermodynamic calculations in process development are described, as are computer codes developed for calculating material flows and phase compositions in pyroprocessing

  17. Partition of actinides and fission products between metal and molten salt phases: Theory, measurement, and application to IFR pyroprocess development

    Energy Technology Data Exchange (ETDEWEB)

    Ackerman, J.P.; Johnson, T.R.

    1993-10-01

    The chemical basis of Integral Fast Reactor fuel reprocessing (pyroprocessing) is partition of fuel, cladding, and fission product elements between molten LiCl-KCl and either a solid metal phase or a liquid cadmium phase. The partition reactions are described herein, and the thermodynamic basis for predicting distributions of actinides and fission products in the pyroprocess is discussed. The critical role of metal-phase activity coefficients, especially those of rare earth and the transuranic elements, is described. Measured separation factors, which are analogous to equilibrium constants but which involve concentrations rather than activities, are presented. The uses of thermodynamic calculations in process development are described, as are computer codes developed for calculating material flows and phase compositions in pyroprocessing.

  18. Potentials of fissioning plasmas

    International Nuclear Information System (INIS)

    Karlheinz, Thom.

    1979-01-01

    Successful experiments with the nuclear pumping of lasers have demonstrated that in gaseous medium the kinetic energy of fission fragments can be converted directly into non-equilibrium optical radiation. This confirms the concept that the fissioning medium in a gas-phase nuclear reactor shows an internal structure such as a plasma in nearly thermal equilibrium varying up to a state of extreme-non-equilibrium. The accompanying variations of temperatures, pressure and radiative spectrum suggest wide ranges of applications. For example, in the gas-phase fission reactor concept enriched uranium hexafluoride or an uranium plasma replaces conventional fuel elements and permits operation above the melting point of solid materials. This potential has been motivation for the US National Aeronautics and Space Administration (NASA) to conduct relevant research for high specific impulse propulsion in space. The need to separate the high temperature gaseous fuel from the surfaces of a containing vessel and to protect them against thermal radiation has led to the concept of an externally moderated reactor in which the fissioning gaseous material is suspended by fluid dynamic means and the flow of opaque buffer gas removes the power. The gaseous nuclear fuel can slowly be circulated through the reactor for continuous on-site reprocessing including the annihilation of transuranium actinides at fission when being fed back into the reactor. An equilibrium of the generation and destruction of such actinides at fission when being fed back into the reactor. An equilibrium of the generation and destruction of such actinides can thus be achieved. These characteristics and the unique radiative properties led to the expectation that the gas-phase fission reactor could feature improved safety, safeguarding and economy, in addition to new technologies such as processing, photochemistry and the transmission of power over large distances in space

  19. Elimination of waste actinides by recycling them to nuclear reactors

    International Nuclear Information System (INIS)

    McKay, H.A.C.

    1981-01-01

    After a few centuries of radioactive decay the long-lived actinides, the elements of atomic numbers 89-103, may constitute the main potential radiological health hazard in nuclear wastes. This is because all but a very few fission products (principally technetium-99 and iodine-129) have by then decayed to insignificant levels, leaving the actinides as the principal hazardous species remaining. It is therefore at first sight an attractive idea to recycle the actinides in nuclear reactors, so as to eliminate them by nuclear fission. There are good reasons for examining the idea in detail, and studies have been carried out in a number of countries. These have culminated recently in international conferences at the European Joint Research Centre at Ispra in Italy and at Austin, Texas in the USA as well as in the issue of an IAEA Technical Report entitled An Evaluation of Actinide Partitioning and Transmutation, a product of a four-year IAEA Co-ordinated Research Programme, on which the present article is based. The term partitioning refers to the separation of the actinides from nuclear fuel cycle wastes, a necessary preliminary step to their introduction into reactors for transmutation by nuclear fission. The complete scheme will be referred to as P-T, i.e. partitioning-transmutation

  20. Separation of actinides and their transmutation

    International Nuclear Information System (INIS)

    Bouchard, M.; Bathelier, M.; Cousin, M.

    1978-08-01

    Neutron irradiation of long-half-life actinides for transmutation into elements with shorter half-life is investigated as a means to reduce the long-term hazards of these actinides. The effectiveness of the method is analysed by applying it to fission product solutions from the first extraction cycle of fuel reprocessing plants. Basic principles, separation techniques and transmutation efficiencies are studied and discussed in detail

  1. Influence of pairing correlations on the probability and dynamics of tunneling through the barrier in fission and fusion of complex nuclei

    International Nuclear Information System (INIS)

    Lazarev, Yu.A.

    1986-01-01

    An analytically solvable model is used to study the potential barrier penetrability in the case when the gap parameter Δ is treated as a dynamical variable governed by the least action principle. It is found that, as compared to the standard (BCS) approach, the dynamical treatment of pairing results in a considerably weakened dependence of the fission barrier penetrability on the intensity of pairing correlations in the initial state (Δ 0 ), on the barrier height, and on the energy of the initial state. On this basis, a more adequate explanation is proposed for typical order-of-magnitude values of the empirical hidrance factors for groun-state spontaneous fission of odd nuclei. It is also shown that a large enhancement of superfluidity in tunneling - the inherent effect of the dynamical treatment of pairing - strongly facilitates deeply subbarier fusion of complex nuclei. Finally, an analysis is given for the probability of spontaneous fission from K-isomeric quasiparticle (q-p) states in even-even heavy nuclei. The relative change of the partial spontaneous fission half-life in going from the ground-state to a high-spin q-p isomeric state, T* sf /T sf , is found to be strongly dependent on whether or not there takes place the dynamically induced enhancement of superfluidity in tunneling. Measurements of T* sf /T sf provide thus a unique possibility of verifying theoretical predictions about the strong, inverse-square Δ dependence of the effective inertia associated with large-scale subbarrier rearrangements of nuclei

  2. Actinide recycling in reactors

    International Nuclear Information System (INIS)

    Kuesters, H.; Wiese, H.W.; Krieg, B.

    1995-01-01

    The objective is an assessment of the transmutation of long-lived actinides and fission products and the incineration of plutonium for reducing the risk potential of radioactive waste from reactors in comparison to direct waste disposal. The contribution gives an interim account on homogeneous and heterogeneous recycling of 'risk nuclides' in thermal and fast reactors. Important results: - A homogeneous 5 percent admixture of minor actinides (MA) from N4-PWRs to EFR fuel would allow a transmutation not only of the EFR MA, but in addition of the MA from 5 or 6 PWRs of equal power. However, the incineration is restricted by safety considerations. - LWR have only a very low MA incineration potential, due to their disadvantageous neutron capture/fission ratio. - In order to keep the Cm inventory at a low level, it is advantageous to concentrate the Am heterogeneously in particular fuel elements or rods. (orig./HP)

  3. Computational Benchmark for Estimation of Reactivity Margin from Fission Products and Minor Actinides in PWR Burnup Credit

    International Nuclear Information System (INIS)

    Wagner, J.C.

    2001-01-01

    This report proposes and documents a computational benchmark problem for the estimation of the additional reactivity margin available in spent nuclear fuel (SNF) from fission products and minor actinides in a burnup-credit storage/transport environment, relative to SNF compositions containing only the major actinides. The benchmark problem/configuration is a generic burnup credit cask designed to hold 32 pressurized water reactor (PWR) assemblies. The purpose of this computational benchmark is to provide a reference configuration for the estimation of the additional reactivity margin, which is encouraged in the U.S. Nuclear Regulatory Commission (NRC) guidance for partial burnup credit (ISG8), and document reference estimations of the additional reactivity margin as a function of initial enrichment, burnup, and cooling time. Consequently, the geometry and material specifications are provided in sufficient detail to enable independent evaluations. Estimates of additional reactivity margin for this reference configuration may be compared to those of similar burnup-credit casks to provide an indication of the validity of design-specific estimates of fission-product margin. The reference solutions were generated with the SAS2H-depletion and CSAS25-criticality sequences of the SCALE 4.4a package. Although the SAS2H and CSAS25 sequences have been extensively validated elsewhere, the reference solutions are not directly or indirectly based on experimental results. Consequently, this computational benchmark cannot be used to satisfy the ANS 8.1 requirements for validation of calculational methods and is not intended to be used to establish biases for burnup credit analyses

  4. Fission dynamics of excited nuclei within the liquid-drop model

    CERN Document Server

    Radionov, S V; Kolomietz, V M; Magner, A G

    2002-01-01

    The temperature T sub s sub c sub i sub s at the scission point and the saddle-to-scission time tau sub s sub c sub i sub s for the fission of heated nuclei is evaluated. The classical Lagrange-like equations of motion within the liquid-drop model are used. The nuclear surface is parametrized by the two-parametric family of the Lawrence shapes. Conservative forces are defined through the free energy of the nucleus at finite temperatures. The friction tensor derived from the Navier-Stokes momentum flux tensor taking into account the boundary conditions on the nuclear surface is used. The scission line is determined from the instability condition of the nuclear shape with respect to the variations of the neck radius. The numerical solution of the dynamical equations is performed for the nucleus sup 2 sup 3 sup 6 U. The viscosity coefficient mu was obtained from the comparison of the experimental data for the kinetic energy for the fission fragments with the computed one. A significant deviation of mu, obtained ...

  5. Fission dynamics of excited nuclei within the liquid-drop model

    International Nuclear Information System (INIS)

    Radionov, S.V.; Ivanyuk, F.A.; Kolomietz, V.M.; Magner, A.G.

    2002-01-01

    The temperature T scis at the scission point and the saddle-to-scission time τ scis for the fission of heated nuclei is evaluated. The classical Lagrange-like equations of motion within the liquid-drop model are used. The nuclear surface is parametrized by the two-parametric family of the Lawrence shapes. Conservative forces are defined through the free energy of the nucleus at finite temperatures. The friction tensor derived from the Navier-Stokes momentum flux tensor taking into account the boundary conditions on the nuclear surface is used. The scission line is determined from the instability condition of the nuclear shape with respect to the variations of the neck radius. The numerical solution of the dynamical equations is performed for the nucleus 236 U. The viscosity coefficient μ was obtained from the comparison of the experimental data for the kinetic energy for the fission fragments with the computed one. A significant deviation of μ, obtained by used approach, from μ of the standard hydrodynamical model is found [ru

  6. Fusion-fission probabilities, cross sections, and structure notes of superheavy nuclei

    International Nuclear Information System (INIS)

    Kowal, Michał; Cap, Tomasz; Jachimowicz, Piotr; Skalski, Janusz; Siwek-Wilczyńska, Krystyna; Wilczyński, Janusz

    2016-01-01

    Fusion – fission probabilities in the synthesis of heaviest elements are discussed in the context of the latest experimental reports. Cross sections for superheavy nuclei are evaluated using the “Fusion by Diffusion” (FBD) model. Predictive power of this approach is shown for experimentally known Lv and Og isotopes and predictions given for Z = 119, 120. Ground state and saddle point properties as masses, shell corrections, pairing energies, and deformations necessary for cross-section estimations are calculated systematically within the multidimensional microscopic-macroscopic method based on the deformed Woods-Saxon single-particle potential. In the frame of the FBD approach predictions for production of elements heavier than Z = 118 are not too optimistic. For this reason, and because of high instability of superheavy nuclei, we comment on some structure effects, connected with the K-isomerism phenomenon which could lead to a significant increase in the stability of these systems.

  7. Measurements of Fission Cross Sections of Actinides

    CERN Multimedia

    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.

  8. Systematics of neutron-induced fission yields

    International Nuclear Information System (INIS)

    Blachot, J.; Brissot, R.

    1983-10-01

    The main characteristics of the mass and charge distributions for thermal neutron induced fission of actinides are reviewed. We show that these distributions can be reasonably reproduced with only 24 data as input. We use a representation where the element yields together with the most probable mass Ap(Z) play the dominant role. The ability of this model to calculate mass yields for the fission of not yet measured actinides is also shown. The influence of the excitation energy of the fissile system on charge and mass distribution is also discussed

  9. Consultancy to review and finalize the IAEA publication 'Compendium on the use of fusion/fission hybrids for the utilization and transmutation of actinides and long-lived fission products'. Working material

    International Nuclear Information System (INIS)

    2004-01-01

    In addition to the traditional fission reactor research, fusion R and D activities are becoming of interest also to nuclear fission power development. There is renewed interest in utilizing fusion neutrons, Heavy Liquid Metals, and molten salts for innovative systems (energy production and transmutation). Indeed, for nuclear power development to become sustainable as a long-term energy option, innovative fuel cycle and reactor technologies will have to be developed to solve the problems of resource utilization and long-lived radioactive waste management. In this context Member States clearly expressed the need for comparative assessments of various transmutation reactors. Both the fusion and fission communities are currently investigating the potential of innovative reactor and fuel cycle strategies that include a fusion/fission system. The attention is mainly focused on substantiating the potential advantages of such systems: utilization and transmutation of actinides and long-lived fission products, intrinsic safety features, enhanced proliferation resistance, and fuel breeding capabilities. An important aspect of the ongoing activities is the comparison with the accelerator driven subcritical system (spallation neutron source), which is the other main option for producing excess neutrons. Apart from comparative assessments, knowledge preservation is another subject of interest to the Member States: the goal, applied to fusion/fission systems, is to review the status of, and to produce a 'compendium' of past and present achievements in this area

  10. Simulations of the Thermodynamic and Diffusion Properties of Actinide Oxide Fuel Materials

    International Nuclear Information System (INIS)

    Becker, Udo

    2013-01-01

    Spent nuclear fuel from commercial reactors is comprised of 95-99 percent UO 2 and 1-5 percent fission products and transuranic elements. Certain actinides and fission products are of particular interest in terms of fuel stability, which affects reprocessing and waste materials. The transuranics found in spent nuclear fuels are Np, Pu, Am, and Cm, some of which have long half- lives (e.g., 2.1 million years for 237 Np). These actinides can be separated and recycled into new fuel matrices, thereby reducing the nuclear waste inventory. Oxides of these actinides are isostructural with UO 2 , and are expected to form solid solutions. This project will use computational techniques to conduct a comprehensive study on thermodynamic properties of actinide-oxide solid solutions. The goals of this project are to: Determine the temperature-dependent mixing properties of actinide-oxide fuels; Validate computational methods by comparing results with experimental results; Expand research scope to complex (ternary and quaternary) mixed actinide oxide fuels. After deriving phase diagrams and the stability of solid solutions as a function of temperature and pressure, the project team will determine whether potential phase separations or ordered phases can actually occur by studying diffusion of cations and the kinetics of potential phase separations or ordered phases. In addition, the team will investigate the diffusion of fission product gases that can also have a significant influence on fuel stability. Once the system has been established for binary solid solutions of Th, U, Np, and Pu oxides, the methodology can be quickly applied to new compositions that apply to ternaries and quaternaries, higher actinides (Am, Cm), burnable poisons (B, Gd, Hf), and fission products (Cs, Sr, Tc) to improve reactivity

  11. Fission cross section and fission fragment angular distribution for oriented nucleus fission by intermediate energy neutrons (epsilon < or approximately 1 Mev)

    International Nuclear Information System (INIS)

    Barabanov, A.L.; Grechukhin, D.P.

    1985-01-01

    General analysis is conducted, and formulae for fission cross section and angular distribution of fission fragments of oriented nuclei by fast neutrons are presented. Geometrical coefficients making up the formulae permitting to carry out calculations for target nuclei with spins I=3/2, 5/2, 7/2 at interaction energies epsilon < or approximately 1 MeV are tabulated. Results of demonstrative calculation of fission fragment angular distribution of oriented sup(235)U nuclei by 0.1 <= epsilon <= 1.0 MeV neutrons reveal that angular distribution weakly depends on the set of permeability factors of neutron waves applied in the calculations

  12. TMI-2 decay power: LASL fission-product and actinide decay power calculations for the President's Commission at Three Mile Island

    Energy Technology Data Exchange (ETDEWEB)

    England, T.R.; Wilson, W.B.

    1979-10-01

    Fission-product and actinide decay heating, gas content, curies, and detailed contributions of the most important nuclide contributors were supplied in a series of letters following requests from the Presidential Commission on the Accident at Three Mile Island. In addition, similar data assuming different irradiation (power) histories were requested for purposes of comparison. This report consolidates the tabular and graphical data supplied and explains its basis.

  13. Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum; Fission des noyaux lourds: etude microscopique des barrieres de fission et du moment angulaire des fragments

    Energy Technology Data Exchange (ETDEWEB)

    Bonneau, L

    2003-11-01

    A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J{sup 2} in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J{sup 2} operator. (A.C.)

  14. True ternary fission in 310126X

    International Nuclear Information System (INIS)

    Banupriya, B.; Vijayaraghavan, K.R.; Balasubramaniam, M.

    2015-01-01

    All possible combinations are minimized by the two dimensional minimization process and minimized with respect to neutron numbers and proton numbers of the fragments. Potential energy is low and Q - value is high at true ternary fission region. It shows that true ternary mode is the dominant mode in the ternary fission of superheavy nuclei. Also, the results show that the fragments with neutron magic numbers are the dominant one in the ternary fission of superheavy nuclei whereas the fragments with proton magic numbers are the dominant one in the ternary fission of heavy nuclei

  15. Neutron nuclear data evaluation for actinide nucleic

    International Nuclear Information System (INIS)

    Chen Guochang; Yu Baosheng; Duan Junfeng; Ge Zhigang; Cao Wentian; Tang Guoyou; Shi Zhaomin; Zou Yubin

    2010-01-01

    The nuclear data with high accuracy for minor actinides are playing an important role in nuclear technology applications, including reactor design and operation, fuel cycle concepts, estimation of the amount of minor actinides in high burn-up reactors and the minor actinides transmutation. Through describe the class of nuclear data and nuclear date library, and introduce the procedure of neutron nuclear data evaluation. 234 U(n, f) and 237 Np(n, 2n) reaction experimental data evaluation was evaluated. The fission nuclear data are updated and improved. (authors)

  16. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    The fission-like configurations are used for the total deformation energy calculations. A ... oscillator potential for the two fission fragment regions reads as ... Beyond this limit, the contribution of more remote levels is negligible. Once the density ...

  17. Transmutation of LWR waste actinides in thermal reactors

    International Nuclear Information System (INIS)

    Gorrell, T.C.

    1979-01-01

    Recycle of actinides to a reactor for transmutation to fission products is being considered as a possible means of waste disposal. Actinide transmutation calculations were made for two irradiation options in a thermal (LWR) reactor. The cases considered were: all actinides recycled in regular uranium fuel assemblies, and transuranic actinides recycled in separate mixed oxide (MOX) assemblies. When all actinides were recycled in a uranium lattice, a reduction of 62% in the transuranic inventory was achieved after 10 recycles, compared to the inventory accumulated without recycle. When the transuranics from 2 regular uranium assemblies were combined with those recycled from a MOX assembly, the transuranic inventory was reduced 50% after 5 recycles

  18. Langevin description of mass distributions of fragments originating from the fission of excited nuclei

    International Nuclear Information System (INIS)

    Vanin, D.V.; Nadtochy, P.N.; Adeev, G.D.; Kosenko, G.I.

    2000-01-01

    A stochastic approach to fission dynamics is proposed. The approach, which is based on Langevin equations, is used to calculate the mass distributions of fragments originating from the fission of excited nuclei. The effect of viscosity and light-particle emission on the variance of mass distributions is studied. The results of the calculations based on the above approach reveal that, in order to obtain a simultaneous description of mass-distribution parameters and the multiplicities of prescission particles, it is necessary to use sufficiently large values of nuclear viscosity both for the one-body and for the two-body viscosity mechanism, anomalously large values of the viscosity coefficient being required in the latter case

  19. Determination of fission products and actinides by inductively coupled plasma-mass spectrometry using isotope dilution analysis. A study of random and systematic errors

    International Nuclear Information System (INIS)

    Ignacio Garcia Alonso, Jose

    1995-01-01

    The theory of the propagation of errors (random and systematic) for isotope dilution analysis (IDA) has been applied to the analysis of fission products and actinide elements by inductively coupled plasma-mass spectrometry (ICP-MS). Systematic errors in ID-ICP-MS arising from mass-discrimination (mass bias), detector non-linearity and isobaric interferences in the measured isotopes have to be corrected for in order to achieve accurate results. The mass bias factor and the detector dead-time can be determined by using natural elements with well-defined isotope abundances. A combined method for the simultaneous determination of both factors is proposed. On the other hand, isobaric interferences for some fission products and actinides cannot be eliminated using mathematical corrections (due to the unknown isotope abundances in the sample) and a chemical separation is necessary. The theory for random error propagation in IDA has been applied to the determination of non-natural elements by ICP-MS taking into account all possible sources of uncertainty with pulse counting detection. For the analysis of fission products, the selection of the right spike isotope composition and spike to sample ratio can be performed by applying conventional random propagation theory. However, it has been observed that, in the experimental determination of the isotope abundances of the fission product elements to be determined, the correction for mass-discrimination and the correction for detector dead-time losses contribute to the total random uncertainty. For the instrument used in the experimental part of this study, it was found that the random uncertainty on the measured isotope ratios followed Poisson statistics for low counting rates whereas, for high counting rates, source instability was the main source of error

  20. (d,p)-transfer induced fission of heavy radioactive beams

    CERN Document Server

    Veselsky, Martin

    2012-01-01

    (d,p)-transfer induced fission is proposed as a tool to study low energy fission of exotic heavy nuclei. Primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission offers a possibility for systematic study the low energy fission of heavy exotic nuclei at the ISOLDE.

  1. Fusion-fission type collisions

    International Nuclear Information System (INIS)

    Oeschler, H.

    1980-01-01

    Three examples of fusion-fission type collisions on medium-mass nuclei are investigated whether the fragment properties are consistent with fission from equilibrated compound nuclei. Only in a very narrow band of angular momenta the data fulfill the necessary criteria for this process. Continuous evolutions of this mechnism into fusion fission and into a deep-inelastic process and particle emission prior to fusion have been observed. Based on the widths of the fragment-mass distributions of a great variety of data, a further criterion for the compound-nucleus-fission process is tentatively proposed. (orig.)

  2. Determination of the fission barrier height in fission of heavy radioactive beams induced by the (d,p)-transfer

    CERN Multimedia

    A theoretical framework is described, allowing to determine the fission barrier height using the observed cross sections of fission induced by the (d,p)-transfer with accuracy, which is not achievable in another type of low-energy fission of neutron-deficient nuclei, the $\\beta$-delayed fission. The primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission of...

  3. The US/UK Actinides Experiment at the Dounreay PFR

    International Nuclear Information System (INIS)

    Raman, S.; Walker, R.L.; Dickens, J.K.; Murphy, B.D.

    1997-01-01

    The United States and the United Kingdom have been engaged in a joint research program in which samples of higher actinides were irradiated in the 600-MW Dounreay Prototype Fast Reactor in Scotland. Analytical results using mass spectrometry and radiometry for actinides and fission products are now available for the samples in Fuel Pins 1 and 2, which were irradiated for 63 full-power days, and for the samples in Fuel Pin 4, which were irradiated for 492 full-power days. Results from these three fuel pins are providing estimates of integral cross sections and fission yields

  4. Microscopic description of the competition between spontaneous fission and α -decay in neutron-rich Ra, U and Pu nuclei

    International Nuclear Information System (INIS)

    Rodríguez-Guzmán, R; Robledo, L M

    2017-01-01

    Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in Ra, U and Pu nuclei with neutron number 144 ≤ N ≤ 176. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the spontaneous fission half-lives. We also pay attention to isomeric states along the considered fission paths. Alpha decay half-lives have also been computed using a parametrization of the Viola-Seaborg formula. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation a robust trend is obtained indicating, that with increasing neutron number fission dominates over α -decay. Our results also suggest that a dynamical treatment of pairing correlations is required within the microscopic studies of the fission process in heavy nuclear systems. (paper)

  5. Applications of the nuclear theory to the computation of neutron cross sections for actinide isotopes

    International Nuclear Information System (INIS)

    Konshin, V.A.

    1981-01-01

    Neutron cross section calculational methods for actinides in the unresolved resonance energy range (1-150 kev) are discussed, with a special emphasis on calculation of width fluctuation factors for the generalized distribution, as well as for a sub-threshold fission. It is shown that the energy dependence of sub(J), the (n,n') -process competition and the structure in neutron cross section has to be taken into account in the energy range considered. Analysis of different approaches in the statistical theory for heavy nuclei neutron cross-section calculation is given, and it is shown to be important to allow for the (n,γf)-reaction in neutron cross section calculations for fissile nuclei. The use of the non-spherical potential, the Lorentzian spectral factor and the Fermi-gas model involving the collective modes enables to obtain the self-consistent data for all neutron cross sections, including σnγ. (author)

  6. Preliminary design and neutronic analysis of a laser fusion driven actinide waste burning hybrid reactor

    International Nuclear Information System (INIS)

    Berwald, D.H.; Duderstadt, J.J.

    1979-01-01

    The laser fusion driven actinide waste burner (LDAB) system investigated uses partitioned fission power reactor generated actinide wastes dissolved in a molten tin alloy as feed material (or fuel). A novel fuel processing concept based on the high-temperature precipitation of ''actinide--nitrides'' from a liquid tin solution is proposed. This concept will allow for fission product removal to be performed entirely within the device at high burnup. No attempt has been made to optimize this system, but potential performance is impressive. The equilibrium LDAB design consumes 7.6 MT/y of actinide waste. This corresponds to the waste output from 136 light water reactors [1000 MW (electric)]. The mean life of an actinide atom in the LDAB is only 4.5 y; and actinides, once charged to the LDAB, might be reprocessed fewer times during irradiation than in previously proposed systems

  7. Etude structurale et propriétés des verres peralumineux de conditionnement des produits de fission et actinides mineurs"

    OpenAIRE

    Gasnier , Estelle

    2013-01-01

    In this work, peraluminous glasses (lack of alkaline and alkaline earth ions regarding aluminum) are under study to assess the potentiality of these matrices to confine fission products and minor actinides (FPA) at higher rate than current R7T7 glass (18,5 wt % FPA). The first part of this work aims at studying the physical and chemical properties of complex peraluminous glasses containing increasing FPA rate (18.5 to 32 wt %) to compare them with the specifications. The very low crystallizat...

  8. Study of the isomer nuclei produced in the spontaneous fission of {sup 252}Cf; Etude des noyaux isomeriques produits dans la fission spontanee de {sup 252}Cf

    Energy Technology Data Exchange (ETDEWEB)

    Gautherin, C.; Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Thiesen, Ch. [Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Badimon, C.; Barreau, G.; Doan, T.P.; Pedemay, G. [Centre d`Etudes Nucleaires, Bordeaux-1 Univ., 33 Gradignan (France); Belier, G.; Girod, M.; Meot, M.V. [CEA Centre d`Etudes de Bruyeres-le-Chatel, 91 (France); Astier, G.; Meot, V.; Peru, S. [CEA Centre d`Etudes de Bruyeres-le-Chatel, 91 (France); Astier, A.; Ducroux, L.; Meyer, M.; Redon, N. [Inst.de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)

    1997-06-01

    Isomeric states have been studied in fission fragments produced by spontaneous fission of {sup 252}Cf. 34 isomeric nuclei have been identified by using coincidences between {gamma}-rays detected in EUROGAM II and fission fragments detected in photovoltaic cells. Lifetimes from 20 ns up to 2 {mu}s have been measured. Microscopic interpretation of the isomeric levels discovered has been tried by means of the Hartree-Fock-Bogolyubov procedure using Gogny force. It was found that the {sup 152,154,156}Nd nuclei have prolate deformation in their ground state; the rotational band built on this ground state is well reproduced by the calculation. For these nuclei the 2 quasi-particle excited states energies are above 1 MeV in agreement with the experiment. The computation confirms the similitude of the {sup 156}Nd and {sup 158}Sm isomeric states associated to neutron 2 quasi-particles of J{sup {pi}} K{sup {pi}} = 5{sup -} ({nu} 5/2 (642) x {nu} 5/2 (523)) while such similitude does not occur for the isotone nuclei {sup 154}Nd and {sup 156}Sm. The computation predicts a proton 2 quasi-particle excited states of J{sup {pi}} = 5{sup -}, near the isomeric level measured in {sup 156}Sm but not for that of {sup 154}Nd. Concerning the {sup 152}Nd the calculated level density is very near that of the states measured in the 1.6 to 2.3 MeV interval. However, the lack of precise information on spins and parities of the measured levels does make not possible a confrontation with the calculations. An up-graded equipment implying 32 photovoltaic cells instead of 2 cells is to be developed and installed by the EUROGAM 3 refs.

  9. Study of extraterrestrial disposal of radioactive wastes. Part 3: Preliminary feasibility screening study of space disposal of the actinide radioactive wastes with 1 percent and 0.1 percent fission product contamination

    Science.gov (United States)

    Hyland, R. E.; Wohl, M. L.; Finnegan, P. M.

    1973-01-01

    A preliminary study was conducted of the feasibility of space disposal of the actinide class of radioactive waste material. This waste was assumed to contain 1 and 0.1 percent residual fission products, since it may not be feasible to completely separate the actinides. The actinides are a small fraction of the total waste but they remain radioactive much longer than the other wastes and must be isolated from human encounter for tens of thousands of years. Results indicate that space disposal is promising but more study is required, particularly in the area of safety. The minimum cost of space transportation would increase the consumer electric utility bill by the order of 1 percent for earth escape and 3 percent for solar escape. The waste package in this phase of the study was designed for normal operating conditions only; the design of next phase of the study will include provisions for accident safety. The number of shuttle launches per year required to dispose of all U.S. generated actinide waste with 0.1 percent residual fission products varies between 3 and 15 in 1985 and between 25 and 110 by 2000. The lower values assume earth escape (solar orbit) and the higher values are for escape from the solar system.

  10. Study of fission dynamics of the excited nuclei produced in fusion reactions in the framework of the four-dimensional Langevin equations

    Energy Technology Data Exchange (ETDEWEB)

    Eslamizadeh, H. [Persian Gulf University, Department of Physics, Bushehr (Iran, Islamic Republic of)

    2014-12-01

    The dynamics of fission of excited nuclei has been studied by solving four-dimensional Langevin equations with dissipation generated through the chaos-weighted wall and window friction formula. The projection of the total spin of the compound nucleus to the symmetry axis, K, was considered as the fourth dimension in Langevin dynamical calculations. The average pre-scission neutron multiplicities, mean kinetic energy of fission fragments and the variances of the mass and kinetic energy have been calculated in a wide range of fissile parameter for compound nuclei {sup 162}Yb, {sup 172}Yb, {sup 215}Fr, {sup 224}Th, {sup 248}Cf, {sup 260}Rf and results compared with the experimental data. Calculations were performed with a constant dissipation coefficient of K, {sub γK} (MeV zs){sup -1/2}, and with a non-constant dissipation coefficient. Comparison of the theoretical results for the average pre-scission neutron multiplicities, mean kinetic energy of fission fragments and the variances of the mass and kinetic energy with the experimental data showed that the results of four-dimensional Langevin equations with a non-constant dissipation coefficient are in better agreement with the experimental data. Furthermore, the difference between the results of two models for compound nuclei with low fissile parameter is low whereas, for heavy compound nuclei, is high. (orig.)

  11. TMI-2 decay power: LASL fission-product and actinide decay power calculations for the President's commission on the accident at Three Mile Island

    International Nuclear Information System (INIS)

    England, T.R.; Wilson, W.B.

    1980-03-01

    Fission-product and actinide decay heating, gas content, curies, and detailed contributions of the most important nuclide contributors were supplied in a series of letters following requests from the Presidential Commission on the Accident at Three Mile Island. In addition, similar data assuming different irradiation (power) histories were requested for purposes of comparison. This report consolidates the tabular and graphical data supplied and explains its basis

  12. Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum; Fission des noyaux lourds: etude microscopique des barrieres de fission et du moment angulaire des fragments

    Energy Technology Data Exchange (ETDEWEB)

    Bonneau, L

    2003-11-01

    A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J{sup 2} in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J{sup 2} operator. (A.C.)

  13. Level density parameter dependence of the fission cross sections of some subactinide nuclei induced by protons with the incident energy up to 250 MeV

    International Nuclear Information System (INIS)

    Aydin, A.; Yalim, H.A.; Tel, E.; Sarer, B.; Unal, R.; Sarpuen, I.H.; Kaplan, A.; Dag, M.

    2009-01-01

    This study aims to show the dependence on the choice of the ratio of the level density parameters a f and a n corresponding to the saddle point of fission and equilibrium deformation of nucleus, respectively, of the proton induced fission cross sections of some subactinide targets. The method was employed using different level density parameter ratios for each fission cross section calculation in ALICE/ASH computer code. The ALICE/ASH code calculations were compared both with the available experimental data and with the Prokofiev systematics data. It is found that the fission cross sections dependent heavily on the choice of level density parameter ratio in the fission and neutron emission channels, a f /a n , for some subactinide nuclei. To get a good description of the measured fission cross sections for subactinide nuclei, we used a ratio of the level density parameters in the fission and neutron emission channels, a f /a n , depending both on the target-nucleus and on the energy of the projectile, in agreement with results published in literature.

  14. Recovery and use of fission product noble metals

    International Nuclear Information System (INIS)

    Jensen, G.A.; Rohmann, C.A.; Perrigo, L.D.

    1980-06-01

    Noble metals in fission products are of strategic value. Market prices for noble metals are rising more rapidly than recovery costs. A promising concept has been developed for recovery of noble metals from fission product waste. Although the assessment was made only for the three noble metal fission products (Rh, Pd, Ru), there are other fission products and actinides which have potential value

  15. Nuclear fission studies: from LOHENGRIN to FIPPS

    International Nuclear Information System (INIS)

    Chebboubi, Abdelaziz

    2015-01-01

    Nuclear fission consists in splitting a nucleus, in general an actinide, into smaller nuclei. Despite nuclear fission was discovered in 1939 by Hahn and Strassman, fission models cannot predict the fission observables with an acceptable accuracy for nuclear fuel cycle studies for instance. Improvement of fission models is an important issue for the knowledge of the process itself and for the applications. To reduce uncertainties of the nuclear data used in a nuclear reactor simulation, a validation of the models hypothesis is mandatory. In this work, two features of the nuclear fission were investigated in order to test the resistance of the theories. One aspect is the study of the symmetric fission fragments through the measurement of their yield and kinetic energy distribution. The other aspect is the study of the fission fragment angular momentum.Two techniques are available to assess the angular momentum of a fission fragment. The first one is to look at the properties of the prompt gamma. The new spectrometer FIPPS (Fission Product Prompt gamma-ray Spectrometer), is currently under development at the ILL and will combine a fission filter with a large array of gamma and neutron detectors in order to respond to these issues. The first part of this work is dedicated to the study of the properties of a Gas Filled Magnet (GFM) which is the type of fission filter considered for the FIPPS project.The second part of this work deals with the measurement of isomeric yields and evaluations of the angular momentum distribution of fission fragments. The study of the spherical nucleus 132 Sn shed the light on the current limits of fission models. Finally, the last part of this work is about the measurement of the yields and kinetic energy distributions of symmetric fission fragments. Since models predict the existence of fission modes, the symmetry region is a suitable choice to investigate this kind of prediction. In parallel with all these studies, an emphasis on the

  16. Interpretation of the mechanism of spontaneous fission of heavy nuclei in the framework of dinuclear system conception

    International Nuclear Information System (INIS)

    Volkov, V.V.; Cherepanov, E.A.; Kalandarov, Sh.A.

    2016-01-01

    A new approach to the interpretation of the process of spontaneous fission of heavy nuclei is suggested. It is based on nuclear physics data which are obtained in heavy ion collisions. The process of spontaneous fission consists of three sequential stages: clusterization of the valent nucleons of a heavy nucleus into a light nucleus-cluster, which leads to the formation of a dinuclear system; evolution of the dinuclear system which proceeds by nucleon transfer from the heavy to light nucleus; and decay of the dinuclear system from the equilibrium configuration into two fragments. [ru

  17. Project research on nuclear physical and chemical characteristics of actinide nuclides

    International Nuclear Information System (INIS)

    Yamana, Hajimu; Nakagome, Yoshihiro; Shibata, Seiichi; Fujii, Toshiyuki; Uehara, Akihiro; Shirai, Osamu; Moriyama, Hirotake; Nagai, Takayuki; Yamanaka, Shinsuke; Shinohara, Atsushi; Kurata, Masaki; Myochin, Munetaka; Nakamura, Shoji; Matsuura, Haruaki

    2008-01-01

    The chemical and nuclear physical characteristics of actinide elements have been investigated using the experimental methods and instruments of this laboratory. This laboratory has a facility in which the transuranium elements (TRU) and the long-lived fission products (LLFP) can be dealt with. The utility of this facility has been expected. The investigation on the actinide elements and its fission products have been carried out as a project research from both view points of science and technology. The research reports during three years (2005-07) are described here. (M.H.)

  18. Use of fast reactors for actinide transmutation

    International Nuclear Information System (INIS)

    1993-03-01

    The management of radioactive waste is one of the key issues in today's discussions on nuclear energy, especially the long term disposal of high level radioactive wastes. The recycling of plutonium in liquid metal fast breeder reactors (LMFBRs) would allow 'burning' of the associated extremely long life transuranic waste, particularly actinides, thus reducing the required isolation time for high level waste from tens of thousands of years to hundreds of years for fission products only. The International Working Group on Fast Reactors (IWGFR) decided to include the topic of actinide transmutation in liquid metal fast breeder reactors in its programme. The IAEA organized the Specialists Meeting on Use of Fast Breeder Reactors for Actinide Transmutation in Obninsk, Russian Federation, from 22 to 24 September 1992. The specialists agree that future progress in solving transmutation problems could be achieved by improvements in: Radiochemical partitioning and extraction of the actinides from the spent fuel (at least 98% for Np and Cm and 99.9% for Pu and Am isotopes); technological research and development on the design, fabrication and irradiation of the minor actinides (MAs) containing fuels; nuclear constants measurement and evaluation (selective cross-sections, fission fragments yields, delayed neutron parameters) especially for MA burners; demonstration of the feasibility of the safe and economic MA burner cores; knowledge of the impact of maximum tolerable amount of rare earths in americium containing fuels. Refs, figs and tabs

  19. Advanced Aqueous Separation Systems for Actinide Partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Kenneth L.; Clark, Sue; Meier, G Patrick; Alexandratos, Spiro; Paine, Robert; Hancock, Robert; Ensor, Dale

    2012-03-21

    One of the most challenging aspects of advanced processing of spent nuclear fuel is the need to isolate transuranium elements from fission product lanthanides. This project expanded the scope of earlier investigations of americium (Am) partitioning from the lanthanides with the synthesis of new separations materials and a centralized focus on radiochemical characterization of the separation systems that could be developed based on these new materials. The primary objective of this program was to explore alternative materials for actinide separations and to link the design of new reagents for actinide separations to characterizations based on actinide chemistry. In the predominant trivalent oxidation state, the chemistry of lanthanides overlaps substantially with that of the trivalent actinides and their mutual separation is quite challenging.

  20. Structure of the β-strength function in heavy nuclei and its influence on the β-delayed fission

    International Nuclear Information System (INIS)

    Wene, C.O.; Isosimow, I.N.; Naumow, Y.W.; Klapdor, H.V.

    1978-01-01

    The shape of the beta strength function Ssub(β) for neutron-rich nuclei is discussed. The structure of Ssub(β) is calculated microscopically for the GT-β-decay of 236 , 238 Pa and is shown to be decisive for the probability for β-delayed fission. (orig.) [de

  1. Actinide burning and waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Pigford, T H [University of California, Berkeley, CA (United States)

    1990-07-01

    for the second repository would be emplaced in the first repository. Reprocessing would now include separation of the fission products strontium and cesium. After interim storage for 20-300 years, the remaining cesium would also be emplaced in the first repository. One DOE laboratory proposes an accelerator to destroy actinides and long-lived fission products. The time required for geologic or managed storage is said to be reduced to only one to several centuries.

  2. Actinide burning and waste disposal

    International Nuclear Information System (INIS)

    Pigford, T.H.

    1990-01-01

    for the second repository would be emplaced in the first repository. Reprocessing would now include separation of the fission products strontium and cesium. After interim storage for 20-300 years, the remaining cesium would also be emplaced in the first repository. One DOE laboratory proposes an accelerator to destroy actinides and long-lived fission products. The time required for geologic or managed storage is said to be reduced to only one to several centuries

  3. Advancing the scientific basis of trivalent actinide-lanthanide separations

    International Nuclear Information System (INIS)

    Nash, K.L.

    2013-01-01

    For advanced fuel cycles designed to support transmutation of transplutonium actinides, several options have been demonstrated for process-scale aqueous separations for U, Np, Pu management and for partitioning of trivalent actinides and fission product lanthanides away from other fission products. The more difficult mutual separation of Am/Cm from La-Tb remains the subject of considerable fundamental and applied research. The chemical separations literature teaches that the most productive alternatives to pursue are those based on ligand donor atoms less electronegative than O, specifically N- and S-containing complexants and chloride ion (Cl - ). These 'soft-donor' atoms have exhibited usable selectivity in their bonding interactions with trivalent actinides relative to lanthanides. In this report, selected features of soft donor reagent design, characterization and application development will be discussed. The roles of thiocyanate, aminopoly-carboxylic acids and lactate in separation processes are detailed. (authors)

  4. Fast fission phenomena

    International Nuclear Information System (INIS)

    Gregoire, Christian.

    1982-03-01

    Experimental studies of fast fission phenomena are presented. The paper is divided into three parts. In the first part, problems associated with fast fission processes are examined in terms of interaction potentials and a dynamic model is presented in which highly elastic collisions, the formation of compound nuclei and fast fission appear naturally. In the second part, a description is given of the experimental methods employed, the observations made and the preliminary interpretation of measurements suggesting the occurence of fast fission processes. In the third part, our dynamic model is incorporated in a general theory of the dissipative processes studied. This theory enables fluctuations associated with collective variables to be calculated. It is applied to highly inelastic collisions, to fast fission and to the fission dynamics of compound nuclei (for which a schematic representation is given). It is with these calculations that the main results of the second part can be interpreted [fr

  5. Nuclear molecules in low energy fission of actinides?

    International Nuclear Information System (INIS)

    Pyatkov, Yu.V.; Pashkevich, V.V.; Tishchenko, V.G.; Unzhakova, A.V.; )

    2000-01-01

    A comparison is presented of the fine structure (FS) of the both energy-mass and energy-charge distributions of the fission fragments of thermal neutron induced fission of uranium in the data obtained at different spectrometers. Some peculiarities of the FS observed can be treated as a manifestation of two different types of collective vibrations of the fissioning system on its way to scission [ru

  6. Nuclear spectroscopy by radioactivity. Study of nuclei adjacent to the 82 neutron closed shell and application to fission

    International Nuclear Information System (INIS)

    Carraz, L.-C.

    1974-01-01

    Chemical separation techniques have been developed which make it possible to obtain a certain number of isotopes presenting anomalies in the fission efficiencies (near the magic shell N=82). A short description is given of the fission phenomenon by analysing the selection of isotopes investigated; it is shown how it was possible to explain the results by means of computers and the various chemical separations perfected are described. Thus a study was made of the 144 La direct γ spectrum. It was shown that the anomalies in the fission efficiencies of certain nuclei are apparent only. Hence, it is the presence of isomers and the distribution of the corresponding efficiency between two isomers which are the cause of the apparent weakness of the efficiency of 134 I, 136 I and 136 Cs, and of certain isotopes of Nb(Z=41). The nuclear spectrometry of nuclei of the area N=82 has made it possible to extend the existence of a metastable state to 136 Xe and 138 Ba. The value of the energies of the first 2 + , 4 + , 6 + levels and the half life duration of the 6 + metastable state are given. The discussion of the results and of the models show that the interpretation of the 0 + , 2 + , 4 + of the 82 neutron nuclei by means of a two quasi-particle (protons) model gives a fairly satisfactory description of the various experimental events: elastic scattering, gamma spectrometry and proton transfer reactions; on the other hand the interpretation of higher energy levels, requires the use of more complicated configurations [fr

  7. Partitioning and Transmutation of minor actinides

    International Nuclear Information System (INIS)

    Koch, L.; Wellum, R.

    1991-01-01

    The partitioning of minor actinides from spent fuels and their transmutation into short-lived fission products has been the topic of two dedicated meetings organized jointly by the European Commission and the OECD. The conclusion of the last meeting in 1980, in short, was that partitioning and transmutation of minor actinides, especially in fast reactors, seemed possible. However, the incentive, which would be a reduction of the radiological hazard to the public, was too small if long-lived fission products were not included. Furthermore this meeting showed that minor actinide targets or possible nuclear fuels containing minor actinides for transmutation had not yet been developed. The European Institute for Transuranium Elements took up this task and has carried it out as a small activity for several years. Interests expressed recently by an expert meeting of the OECD/NEA (Paris, 25 April 1989), which was initiated by the proposed Japanese project Omega, led us to the conclusion that the present state of knowledge should be looked at in a workshop environment. Since the Japanese proposal within the project Omega is based on a broader approach we needed this evaluation to assess the relevance of our present activity and wanted to identifiy additional studies which might be needed to cover possible future demands from the public. This workshop was therefore organized, and participants active in the field from EC countries, the USA and Japan were invited

  8. Nuclear fission and fission-product spectroscopy: 3. International workshop on nuclear fission and fission-product spectroscopy

    International Nuclear Information System (INIS)

    Goutte, Heloise; Fioni, Gabriele; Faust, Herbert; Goutte, Dominique

    2005-01-01

    The present book contains the proceedings of the third workshop in a series of workshops previously held in Seyssins in 1994 and 1998. The meeting was jointly organized by different divisions of CEA and two major international laboratories. In the opening address, Prof. B. Bigot, the French High Commissioner for Atomic Energy, outlined France's energy policy for the next few decades. He emphasized the continuing progress of nuclear fission in both technical and economic terms, allowing it to contribute to the energy needs of the planet even more in the future than it does today. Such progress implies a very strong link between fundamental and applied research based on experimental and theoretical approaches. The workshop gathered the different nuclear communities studying the fission process, including topics as the following: - nuclear fission experiments, - spectroscopy of neutron rich nuclei, - fission data evaluation, - theoretical aspects of nuclear fission, - and innovative nuclear systems and new facilities. The scientific program was suggested by an International Advisory Committee. About 100 scientists from 13 different countries attended the conference in the friendly working atmosphere of the Castle of Cadarache in the heart of the Provence. The proceedings of the workshop were divided into 11 sections addressing the following subject matters: 1. Cross sections and resonances (5 papers); 2. Fission at higher energies - I (5 papers); 3. Fission: mass and charge yields (4 papers); 4. Light particles and cluster emission (4 papers); 5. Spectroscopy of neutron rich nuclei (5 papers); 6. Resonances, barriers, and fission times (5 papers); 7. Fragment excitation and neutron emission (4 papers); 8. Mass and energy distributions (4 papers); 9. Needs for nuclear data and new facilities - I (4 papers); 10. Angular momenta and fission at higher Energies - II (3 papers); 11. New facilities - II (2 papers). A poster session of 8 presentations completed the workshop

  9. Reflections on the criticality of special actinide elements

    International Nuclear Information System (INIS)

    Clayton, E.D.

    1987-04-01

    During recent years, the list of nuclides known to be capable of supporting a chain reaction has substantially increased. Since the criticality aspects for some of these nuclides differ in important respects from those of the most common fissile nuclides, 235 92 U, and 239 94 Pu, a new term, ''fissible'' was recently proposed in nuclear engineering to help distinguish differences. Activation energies for fission have been calculated for 41 of the actinide isotopes which are grouped according to four types of nuclides, those with even-Z, even-N, odd-Z, odd-N, odd-Z, even-N, and even-Z, odd-N. With the possible exception of 237 92 U, all fissible isotopes listed have even N. The activation energy for fission is less in the case of the even-Z, even-N isotopes, but almost without eception it is the odd-N isotopes that undergo fission with thermal neutrons and which constitute the principal criticality problem. This paper reviews the criticality and fissionability aspects of the fissile and fissible actinide isotopes. The criticality of aqueous mixtures of fissile and fissible isotopes also is briefly discussed, including limits for criticality control

  10. Reflections on the criticality of special actinide elements

    International Nuclear Information System (INIS)

    Clayton, E.D.

    1987-01-01

    During recent years, the list of nuclides known to be capable of supporting a chain reaction has substantially increased. Since the criticality aspects for some of these nuclides differ in important respects from those of the most common fissile nuclides, 92 235 U, and 94 239 Pu, a new term, ''fissible'' was recently proposed in nuclear engineering to help distinguish differences. Activation energies for fission have been calculated for 41 of the actinide isotopes which are grouped according to four types of nuclides, those with even-Z and even-N, odd-Z and odd-N, odd-Z and even-N, or even-Z and odd-N. With the possible exception of 92 237 U, all fissible isotopes listed have even N. The activation energy for fission is less in the case of the even-Z and even-N isotopes, but almost without exception it is the odd-N isotopes that undergo fission with thermal neutrons and which constitute the principal criticality problem. This paper reviews the criticality and fissionability aspects of the fissile and fissible actinide isotopes. The criticality of aqueous mixtures of fissile and fissible isotopes also is briefly discussed, including limits for criticality control. (author)

  11. Fission and fragmentation of silver and bromine nuclei by 1-6 GeV energy photons

    International Nuclear Information System (INIS)

    Pinheiro Filho, J. de D.

    1983-01-01

    Fission and fragmentation of silver and bromine nuclei induced by bremsstrahlung photons in the maximum energy range of 1-6 GeV are studied. A special technique of nuclear emulsion for the highly ionizing nuclear fragment detection is used in the discrimination between nuclear fission and fragmentation events. Films of Ilford-KO nuclear emulsion (approximatelly 10 20 atoms/cm 2 of Ag, Br) which had been exposed to bremsstrahlung beams in 'Deutsches Elektronen Synchrotron' (DESY, Hamburg) with total doses of approximatelly 10 11 equivalent photons are used. Through a detailed analysis of range, angular and angle between fragment distributions, and empirical relations which permit to estimate nuclear fragment energy, range and velocity, the discrimination between fission and fragmentation events is made. Results related to fragment range distribution, angular distribution, distribution of angle between fragments, distribution of ratio between ranges, velocity distributions, forward/backward ratio, fission and fragmentation cross sections, nuclear fissionability and ternary fission frequency are presented and discussed. The results show that the mean photofragmentation cross section in the internal 1-6 GeV (0,09+-0,02mb) is significant when compared to the photofission (0,29+-0,05mb). It is also shown that the mean photofission cross section between 1 and 6 GeV is great by a factor of approximatelly 10 when compared to the foreseen by the cascade-evaporation nuclear model for monoenergetic photons of 0,6 GeV. (L.C.) [pt

  12. Actinide and Fission Product Partitioning and Transmutation

    International Nuclear Information System (INIS)

    2015-06-01

    The benefits of partitioning and transmutation (P and T) have now been established worldwide and, as a result, many countries are pursuing R and D programmes to advance the technologies associated with P and T. In this context, the OECD Nuclear Energy Agency (NEA) has organised a series of biennial information exchange meetings to provide experts with a forum to present and discuss state-of-the-art developments in the field of partitioning and transmutation since 1990. The OECD Nuclear Energy Agency Information Exchange Meeting on Actinides and Fission Products Partitioning and Transmutation is a forum for experts to present and discuss the state-of-the-art development in the field of P and T. Thirteen meetings have been organised so far and held in Japan, the United States, France, Belgium, Spain, the Republic of Korea and the Czech Republic. This 13. meeting was hosted by Seoul National University (Seoul, Republic of Korea) and was organised in co-operation with the International Atomic Energy Agency (IAEA) and the European Community (EC). The meeting covered strategic and scientific developments in the field of P and T such as: fuel cycle strategies and transition scenarios, the role of P and T in the potential evolution of nuclear energy as part of the future energy mix; radioactive waste management strategies; transmutation fuels and targets; advances in pyro and aqueous separation processes; P and T specific technology requirements (materials, spallation targets, coolants, etc.); transmutation systems: design, performance and safety; impact of P and T on the fuel cycle; fabrication, handling and transportation of transmutation fuels. A total of 103 presentations (39 oral and 64 posters) were discussed among the 110 participants from 19 countries and 2 international organisations. The meeting consisted of one plenary session where national and international programmes were presented followed by 5 technical sessions: - Fuel Cycle Strategies and Transition

  13. Status of fission product yield data

    International Nuclear Information System (INIS)

    Cuninghame, J.G.

    1978-01-01

    The topics covered in this paper are: (a) cumulative yields in thermal neutron fission and in fast fission up to 14 MeV incident neutron energy, (b) dependence of the yields on incident neutron energy and spectrum, (c) independent yields, (d) charge dispersion and distribution, and (e) yields of light particles from ternary fission. The paper reviews information on these subjects for fission of actinides from 232 Th upwards with special emphasis on data published since the 1973 Bologna FPND Panel, compares data sets, and discusses the gaps still to be found in them. (author)

  14. On the safety of conceptual fusion-fission hybrid reactors

    International Nuclear Information System (INIS)

    Kastenberg, W.E.; Okrent, D.; Badham, V.; Caspi, S.; Chan, C.K.; Ferrell, W.J.; Frederking, T.H.K.; Grzesik, J.; Lee, J.Y.; McKone, T.E.; Pomraning, G.C.; Ullman, A.Z.; Ting, T.D.; Kim, Y.I.

    1979-01-01

    A preliminary examination of some potential safety questions for conceptual fusion-fission hybrid reactors is presented in this paper. The study and subsequent analysis was largely based upon one design, a conceptual mirror fusion-fission reactor, operating on the deuterium-tritium plasma fusion fuel cycle and the uranium-plutonium fission fuel cycle. The major potential hazards were found to be: (a) fission products, (b) actinide elements, (c) induced radioactivity, and (d) tritium. As a result of these studies, it appears that highly reliable and even redundent decay heat removal must be provided. Loss of the ability to remove decay heat results in melting of fuel, with ultimate release of fission products and actinides to the containment. In addition, the studies indicate that blankets can be designed which will remain subcritical under extensive changes in both composition and geometry. Magnet safety and the effects of magnetic fields on thermal parameters were also considered. (Auth.)

  15. Cluster expression in fission and fusion in high-dimensional macroscopic-microscopic calculations

    International Nuclear Information System (INIS)

    Iwamoto, Akira; Ichikawa, Takatoshi; Moller, Peter; Sierk, Arnold J.

    2004-01-01

    We discuss the relation between the fission-fusion potential-energy surfaces of very heavy nuclei and the formation process of these nuclei in cold-fusion reactions. In the potential-energy surfaces, we find a pronounced valley structure, with one valley corresponding to the cold-fusion reaction, the other to fission. As the touching point is approached in the cold-fusion entrance channel, an instability towards dynamical deformation of the projectile occurs, which enhances the fusion cross section. These two 'cluster effects' enhance the production of superheavy nuclei in cold-fusion reactions, in addition to the effect of the low compound-system excitation energy in these reactions. Heavy-ion fusion reactions have been used extensively to synthesize heavy elements beyond actinide nuclei. In order to proceed further in this direction, we need to understand the formation process more precisely, not just the decay process. The dynamics of the formation process are considerably more complex than the dynamics necessary to interpret the spontaneous-fission decay of heavy elements. However, before implementing a full dynamical description it is useful to understand the basic properties of the potential-energy landscape encountered in the initial stages of the collision. The collision process and entrance-channel landscape can conveniently be separated into two parts, namely the early-stage separated system before touching and the late-stage composite system after touching. The transition between these two stages is particularly important, but not very well understood until now. To understand better the transition between the two stages we analyze here in detail the potential energy landscape or 'collision surface' of the system both outside and inside the touching configuration of the target and projectile. In Sec. 2, we discuss calculated five-dimensional potential-energy landscapes inside touching and identify major features. In Sec. 3, we present calculated

  16. Fission of intermediate mass nuclei by photons of stopping radiation in the maximum energy range 0,8 - 1,8 MeV

    International Nuclear Information System (INIS)

    Lima, D.A. de.

    1983-07-01

    The fission of intermediate mass nuclei in Al - Ta interval, induced by stopping radiation phtons of maximum energies between 0,8 and 1.8 GeV is studied. Nd and Sm thin targets and Al, Ti, Co, Zr, Nb, Ag, In and Ta thick targets were used, considering all peculiarities inherent to absorption of fission fragments in the target. The samples were exposed into the 2.5 GeV Electron Synchrotron in Bonn Univerity. The fission fragment tracks were registered in foil type detectors using mica muscovite for Sm and Nd, CR-39 for Al and Ti and makrofol for Co, Zr; Nb, Ag, In, Nd and Ta. The track length and track depth angle distributions were measured for determining fission efficiencies. The fission cross sections and nuclear fissionable of the studied elements were evaluated. (M.C.K.) [pt

  17. Microscopic description of fission in odd-mass uranium and plutonium nuclei with the Gogny energy density functional

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Guzman, R. [Kuwait University, Physics Department, Kuwait (Kuwait); Robledo, L.M. [Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain); Universidad Politecnica de Madrid, Center for Computational Simulation, Boadilla del Monte (Spain)

    2017-12-15

    The parametrization D1M of the Gogny energy density functional is used to study fission in the odd-mass Uranium and Plutonium isotopes with A = 233,.., 249 within the framework of the Hartree-Fock-Bogoliubov (HFB) Equal Filling Approximation (EFA). Ground state quantum numbers and deformations, pairing energies, one-neutron separation energies, barrier heights and fission isomer excitation energies are given. Fission paths, collective masses and zero point rotational and vibrational quantum corrections are used to compute the systematic of the spontaneous fission half-lives t{sub SF}, the masses and charges of the fission fragments as well as their intrinsic shapes. Although there exits a strong variance of the predicted fission rates with respect to the details involved in their computation, it is shown that both the specialization energy and the pairing quenching effects, taken into account fully variationally within the HFB-EFA blocking scheme, lead to larger spontaneous fission half-lives in odd-mass U and Pu nuclei as compared with the corresponding even-even neighbors. It is shown that modifications of a few percent in the strengths of the neutron and proton pairing fields can have a significant impact on the collective masses leading to uncertainties of several orders of magnitude in the predicted t{sub SF} values. Alpha-decay lifetimes have also been computed using a parametrization of the Viola-Seaborg formula. (orig.)

  18. Proceedings of the Workshop on Experimental and theoretical problems around actinides for future reactors

    International Nuclear Information System (INIS)

    Kerveno, Maelle; Dupuis, Marc; Bauge, E.; Hilaire, S.; Romain, P.; Morillon, B.; Delaroche, J.P.; Dupuis, M.; Peru, S.; Belier, G.; Bonnet, T.; Laborie, J.M.; Laurent, B.; Ledoux, X.; Varignon, C.; Meot, V.; Bernard, David; Capote, Roberto; Kawano, T.; Bond, E.; Vieira, D.J.; Wilhelmy, J.B.; Raynal, J.; Plompen, Arjan J.M.; Drohe, J.C.; Nankov, N.; Nyman, M.; Rouki, C.; Bacquias, A.; Dessagne, Ph.; Henning, G.; Karam, H.; Kerveno, M.; Rudolf, G.; Thiry, J.C.; Borcea, C.; Negret, A.; Stanoiu, M.; Bucurescu, D.; Deleanu, D.; Filipescu, D.; Ghita, D.; Glodariu, T.; Marginean, N.; Marginean, R.; Mihai, C.; Olacel, A.; Pascu, S.; Sava, T.; Stroe, L.; Goriely, S.; Pavlik, A.; Jericha, E.; Ledoux, X.; Becker, J.A.; Macri, R.; Authier, N.; Hyneck, D.; Jansen, Y.; Legendre, J.; Jacquet, X.; Gunsing, Frank; Henning, Greg

    2014-03-01

    Since the two last decades, in the framework of general researches on future reactors, strong efforts have been devoted to improve the quantity and quality of nuclear data. Indeed, in order to improve safety margins and fuel optimization, but also to develop new kind of reactors or fuel cycles, accurate nuclear data are mandatory. At the end of the twentieth century, nuclear data bases did not reach the required quality level to be used in future reactor simulations. Therefore, both experimentalists and theoreticians, in the framework of several European research programs (HINDAS, NUDATRA, ANDES, CHANDA...), have tried to make the situation better. New sets of precise data measurements concerning fission, capture, (n,xn),..., reaction cross sections for a large variety of nuclei have been initiated. From evaluation point of view, the JEFF project has also improved the quality of nuclear data bases for several nuclei. In parallel, on the theoretical side, progress has also been made concerning cross section modeling in a wide range of energy (eV to GeV). The goal was to provide theoretical models with a good predictive power to feed data bases where experimental data are still missing and where the measurement is too complex. In this context, for example, a new nuclear reaction code TALYS has been developed. Collaboration between experimentalists, theoreticians and evaluators are then of strong interest to make progress. The number of problems to be solved covers various fields of nuclear reactions such as fission, capture or inelastic scattering. In order to avoid too large an audience we have decided, as a first step, to focus on inelastic scattering on actinides. Experimentally, three main methods exist to measure the total inelastic cross section: activation, detection of the emitted neutrons and prompt-gamma spectroscopy. This last method is, nevertheless, dependent on theoretical models since it provides (n,xn γ) cross sections and not the total inelastic

  19. Nuclear transmutation of actinides other than fuel as a radioactive waste management scheme

    International Nuclear Information System (INIS)

    Cecille, L.; Hage, W.; Hettinger, H.; Mannone, F.; Mousty, F.; Schmidt, E.; Sola, A.; Huber, B.; Koch, L.

    1977-01-01

    The bulk of fission products in the high-level waste (HLW) decays to innocuous hazard levels within about 600 years. Actinide waste and a few fission products however represent a potential risk up to some hundreds of thousand of years. An alternative to the disposal of the whole HLW in geological formations is its fractionation, a nuclear transmutation of long-lived isotopes in fission reactors and a geological disposal of the other components. This solution would decrease the potential long-term risks of the geological waste disposal and would also accomodate to the demand of public opinion. The results of studies related to this management scheme are outlined with special reference to areas, where additional effort is required for realistic cost/benefit evaluations. Reactor physics calculations demonstrated the feasibility of actinide incineration in thermal and fast reactors. Obtained transmutation rates are sufficiently high to garantee acceptably small actinide inventories in the reactor in the case of self-generated actinide recycling. It appears that fast breeders could be used as transmutation devices without major additional reactor devlopment work. The thermal power rating of actinide fuel elements and the contribution of actinides and of minor amounts of lanthanide impurities to the neutron economy of the reactor has been evaluated. Sensitivity studies indicated that the results are dependent on the reactor operation mode and on the accuracy of the nuclear data. These calculations permitted the identification of isotopes for which cross section masurements and improved theoretical methods are required. The chemical separation of actinides from the HLW with the envisaged decontamination factors is being studied by solvent extraction and precipitation techniques using waste simulates and samples of high activity waste from European reprocessing plants. Up to now, the obtained results do not yet allow a definitive judgement on the feasibility of actinides

  20. Nuclear isomerism in fission fragments produced by the spontaneous fission of {sup 252}Cf; Isomerisme nucleaire dans les fragments de fission produits dans la fission spontanee du {sup 252}Cf

    Energy Technology Data Exchange (ETDEWEB)

    Gautherin, C

    1997-09-01

    This thesis is devoted to the study of the nuclear structure of neutron-rich nuclei, via the search of isomeric nuclear states. Neutron-rich nuclei were produced in the spontaneous fission of {sup 252}Cf. The experimental study of isomeric states in these nuclei was performed with the {gamma}-array EUROGAM II, coupled to an additional and original fission fragment detector composed by photovoltaic cells, SAPhIR. The photovoltaic cells are well adapted to detect low energy heavy ions and have good energy and time resolutions to obtain a good fission fragment detection. This experiment led to the discovery of new isomeric states in {sup 135}Xe, {sup 104}Mo, {sup 146,147,148}Ce and {sup 152,154,156}Nd, with lifetimes between 60 ns and 2 {mu}s. Level schemes of these nuclei have been completed. An interpretation of the isomeric states in the nuclei {sup 154,156}Nd and {sup 156,158}Sm was performed by Hartree-Fock-Bogolyubov calculations using the DIS Gogny force with two quasi-particles excitations. The confrontation with the experimental results led to an interpretation of these isomeric states as K-isomers. (author)

  1. Superheavy nuclei and quasi-atoms produced in collisions of transuranium ions

    International Nuclear Information System (INIS)

    Zagrebaev, V.; Oganessian, Y.; Itkis, M.; Greiner, W.

    2005-01-01

    , may remain in contact rather long time. This time delay (up to 10 -19 s) could significantly increase the yield of the so-called spontaneous positron emission from super-strong electric field of quasi-atoms by a static QED process (transition from neutral to charged QED vacuum). This effect was searched sometime ago at GSI but no clear evidences of it have been found. New experiments may be performed now based on our new knowledge of collision dynamics of these nuclei. About twenty years ago damped collisions of very heavy nuclei have been used also for production of chemically separated long-lived actinides. The cross sections were found to be exponentially decreasing with increase of a charge number of heavier fragment, up to the level of 0.1 μb for production of Md isotopes in U + Cm collisions. A new effect, which we found here, is the 'inverse quasi-fission' process. In this process a superheavy nuclear system, say Th + Cf, travelling over the multidimensional potential energy surface, changes its mass asymmetry and may fall into the so-called lead valley. If Th comes to Pb, then Cf grows to the element 106. In spite of rather high excitation energy and low survival probability of residual fragments, this effect significantly increases the yield of nuclei complementary to lead and give us a new way for production of neutron rich (more close to the island of stability) superheavy elements in addition to the extensively used complete fusion reactions. These and some other prospects of subsequent theoretical and experimental studies along with possible collaborations in the field will be discussed in the talk

  2. Leaching of actinides and fission products from ILW embedded in cement and bitumen, and their mobility in natural salt rock

    International Nuclear Information System (INIS)

    Flambard, A.R.; Keiling, C.; Fusban, H.U.; Marx, G.

    1986-01-01

    Real and simulated ILW embedded in cement and bitumen has been subjected to leaching through various binary brines. The resulting solutions containing americium, plutonium, cesium, antimony, ruthenium, cobalt, and strontium have been led through columns packed with the natural Na3γ salt rock from the Gorleben salt dome, in order to determine the mobility characteristics of these elements in the near-field range of a projected waste repository in the Gorleben salt dome, specifically for the case of water intrusion. Leaching data and experimental results are explained and discussed, special attention being given to the impact of the pH-value of the systems studied, and to the formation of carrier (or 'pseudo') colloids during radionuclide release. The paper also gives data obtained on the mobility of transuranium elements and fission products, together with information on differences in behaviour of the actinides and the fission products (ruthenium in particular). (orig.) [de

  3. Calculation of multidimensional potential energy surfaces for even-even transuranium nuclei: systematic investigation of the triaxiality effect on the fission barrier

    Science.gov (United States)

    Chai, Qing-Zhen; Zhao, Wei-Juan; Liu, Min-Liang; Wang, Hua-Lei

    2018-05-01

    Static fission barriers for 95 even-even transuranium nuclei with charge number Z = 94–118 have been systematically investigated by means of pairing self-consistent Woods-Saxon-Strutinsky calculations using the potential energy surface approach in multidimensional (β 2, γ, β 4) deformation space. Taking the heavier 252Cf nucleus (with the available fission barrier from experiment) as an example, the formation of the fission barrier and the influence of macroscopic, shell and pairing correction energies on it are analyzed. The results of the present calculated β 2 values and barrier heights are compared with previous calculations and available experiments. The role of triaxiality in the region of the first saddle is discussed. It is found that the second fission barrier is also considerably affected by the triaxial deformation degree of freedom in some nuclei (e.g., the Z=112–118 isotopes). Based on the potential energy curves, general trends of the evolution of the fission barrier heights and widths as a function of the nucleon numbers are investigated. In addition, the effects of Woods-Saxon potential parameter modifications (e.g., the strength of the spin-orbit coupling and the nuclear surface diffuseness) on the fission barrier are briefly discussed. Supported by National Natural Science Foundation of China (11675148, 11505157), the Project of Youth Backbone Teachers of Colleges and Universities of Henan Province (2017GGJS008), the Foundation and Advanced Technology Research Program of Henan Province (162300410222), the Outstanding Young Talent Research Fund of Zhengzhou University (1521317002) and the Physics Research and Development Program of Zhengzhou University (32410017)

  4. Impact of fuel chemistry on fission product behaviour

    International Nuclear Information System (INIS)

    Poortmans, C.; Van Uffelen, P.; Van den Berghe, S.

    1999-01-01

    The report contains a series of papers presented at SCK-CEN's workshop on the impact of fuel chemistry on fission product behaviour. Contributing authors discuss different processes affecting the behaviour of fission products in different types of spent nuclear fuel. In addition, a number of papers discusses the behaviour of actinides and fission products released from spent fuel and vitrified high-level waste in geological disposal conditions

  5. Plutonium and minor actinide transmutation by long irradiation in LWR

    International Nuclear Information System (INIS)

    Facchini, A.; Sanjust, V.

    1993-01-01

    An investigation was made on the conceptual possibility of burning in a thermal reactor MOX fuel together with special pins containing plutonium, minor actinides and long lived fission products, recovered from the reprocessing of previously irradiated MOX fuel and mixed with an inter matrix. Preliminary calculations showed that the long term radiotoxicity of the above special pins is reduced to reasonable levels when they are irradiated up to 20 divided-by 30 years, and cooled for some centuries. In particular, during the whole life such a reactor should be able to burn a considerable fraction of plutonium, minor actinides and long lived fission products recovered from the MOX fuel irradiated along the same period of time

  6. Fission of Weakly Prolate 119Sn and Weakly Oblate 209Bi Nuclei Induced by 500 and 672 MeV Negative Pions

    International Nuclear Information System (INIS)

    Rana, Mukhtar Ahmed; Sher, Gul; Manzoor, Shahid; Shahzad, M. I.

    2011-01-01

    Fission cross-sections of 119 Sn and 209 Bi induced by negative pions of two energies 500 and 672 MeV were measured using a CR-39 nuclear track detector. Target-detector stacks were exposed to pion beams at the Brookhaven National Laboratory (USA). Measurement results are compared with the corresponding calculations using the computer code CEM95. Agreement between measurements and calculations is fairly good for the 209 Bi target nuclei whereas it is poor for 119 Sn at both investigated energies of 500 and 672 MeV. Fission cross-section results of 119 Sn and 209 Bi are explained using the equilibrium properties of these nuclides including nuclear electric quadrupole moments which determine the shapes of nuclei. A logarithmic dependence of fission cross-section on Z 2 /A is observed for the above-mentioned reactions and a critical limit of Z 2 /A is identified with the value of 30 which divides the curve of σ f versus Z 2 /A into two regimes, one with weak dependence and the other with strong dependence. (nuclear physics)

  7. Fission of Weakly Prolate 119Sn and Weakly Oblate 209Bi Nuclei Induced by 500 and 672 MeV Negative Pions

    Science.gov (United States)

    Mukhtar, Ahmed Rana; Gul, Sher; Shahid, Manzoor; I. Shahzad, M.

    2011-09-01

    Fission cross-sections of 119Sn and 209Bi induced by negative pions of two energies 500 and 672 MeV were measured using a CR-39 nuclear track detector. Target-detector stacks were exposed to pion beams at the Brookhaven National Laboratory (USA). Measurement results are compared with the corresponding calculations using the computer code CEM95. Agreement between measurements and calculations is fairly good for the 209Bi target nuclei whereas it is poor for 119Sn at both investigated energies of 500 and 672 MeV. Fission cross-section results of 119Sn and 209Bi are explained using the equilibrium properties of these nuclides including nuclear electric quadrupole moments which determine the shapes of nuclei. A logarithmic dependence of fission cross-section on Z2/A is observed for the above-mentioned reactions and a critical limit of Z2/A is identified with the value of 30 which divides the curve of σf versus Z2/A into two regimes, one with weak dependence and the other with strong dependence.

  8. Binary scission configurations in fission of light actinides

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsuki, Tsutomu [Tohoku Univ., Sendai (Japan). Lab. of Nuclear Science; Nagame, Y.; Nishinaka, I.; Tsukada, K.; Ikezoe, H.; Tanikawa, M.; Zhao, Y.L.; Sueki, K.; Nakahara, H.

    1997-07-01

    Mass and kinetic energy distributions of fission fragments have been accurately measured by a double velocity time-of-flight technique in the 13 MeV proton-induced fissions of {sup 232}Th and {sup 238}U. A binary structure is observed in total kinetic energy distributions in the fragments with mass number around A=130 for both the fissions, indicating that there are at least two kinds of scission configurations. A correlation between the scission configurations and mass yield distributions reveals that elongated scission configurations are associated with the symmetric mass distribution and compact scission configurations with the asymmetric mass distribution. (author)

  9. Neutron-induced cross sections of short-lived nuclei via the surrogate reaction method

    Directory of Open Access Journals (Sweden)

    Morel P.

    2011-10-01

    Full Text Available The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.

  10. Neutron-induced cross sections of short-lived nuclei via the surrogate reaction method

    Directory of Open Access Journals (Sweden)

    Tassan-Got L.

    2012-02-01

    Full Text Available The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.

  11. Advances in Metallic Fuels for High Burnup and Actinide Transmutation

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, S. L.; Harp, J. M.; Chichester, H. J. M.; Fielding, R. S.; Mariani, R. D.; Carmack, W. J.

    2016-10-01

    Research and development activities on metallic fuels in the US are focused on their potential use for actinide transmutation in future sodium fast reactors. As part of this application, there is a desire to demonstrate a multifold increase in burnup potential. A number of metallic fuel design innovations are under investigation with a view toward significantly increasing the burnup potential of metallic fuels, since higher discharge burnups equate to lower potential actinide losses during recycle. Promising innovations under investigation include: 1) lowering the fuel smeared density in order to accommodate the additional swelling expected as burnups increase, 2) utilizing an annular fuel geometry for better geometrical stability at low smeared densities, as well as the potential to eliminate the need for a sodium bond, and 3) minor alloy additions to immobilize lanthanide fission products inside the metallic fuel matrix and prevent their transport to the cladding resulting in fuel-cladding chemical interaction. This paper presents results from these efforts to advance metallic fuel technology in support of high burnup and actinide transmutation objectives. Highlights include examples of fabrication of low smeared density annular metallic fuels, experiments to identify alloy additions effective in immobilizing lanthanide fission products, and early postirradiation examinations of annular metallic fuels having low smeared densities and palladium additions for fission product immobilization.

  12. Fission and r-process nucleosynthesis in neutron star mergers

    International Nuclear Information System (INIS)

    Giuliani, Samuel Andrea

    2018-01-01

    Fission plays a crucial role for the r-process nucleosynthesis in neutron star mergers. Due to the high neutron densities achieved in this astrophysical scenario the sequence of neutron captures and beta decays that constitutes the r process produces superheavy neutron rich nuclei that become unstable against fission. Fission determines thus the heaviest nuclei that can be produced by the r process and the fission yields shape the abundances of lighter nuclei. But despite the key role of fission the sensitivity of the r-process nucleosynthesis to uncertainties in fission predictions has not been explored. Nowadays there are only few set of fission rates suited for r-process calculations and most of them rely on a simplified treatment of the fission process. In this thesis we go beyond these approximations and compute the fission properties of r-process nuclei using the energy density functional approach. Fission is described as a tunneling process where the nucleus ''moves'' in a collective space characterized by coordinates describing the nuclear shape. Thus fission depends on the evolution of the energy with the deformation but also on the inertia due to the motion in the collective space. This is analogous to the quantum mechanical tunneling of a particle inside a potential well. In our study the relevant quantities for the description of the fission process are consistently computed for 3642 nuclei following the Hartree-Fock-Bogolyubov theory with constraining operators. We perform an extensive benchmark against the available experimental data and explore the variations of the fission properties along the superheavy landscape. We find that while collective inertias have a strong impact in the fission probabilities of light nuclei their role becomes less relevant in r -process nuclei. Within the statistical model we compute the neutron induced stellar reaction rates relevant for the r-process nucleosynthesis. These sets of stellar reaction

  13. Emission of light charged particles from fragments produced on fission of uranium nuclei by 153 MeV protons and 1700 MeV negative pions

    International Nuclear Information System (INIS)

    Belovitzky, G.E.; Shteingrad, O.M.

    2000-01-01

    The mechanism underlying the emission of light charged particles (LCP) with Z = 1, 2 from fragments produced in fission of uranium nuclei by 153 MeV protons and 1700 MeV negative pions was studied. It was found that LCP accompanying the fission by pions are emitted from non-accelerated fragments immediately after the fission, whereas in the case of 153 MeV protons, the LCP are emitted from the accelerated heavy fragments. The number of LCP emitted in the course of pion-induced fission is 0.7 per fission event, which exceeds by a factor of 30 the corresponding number for 153 MeV protons [ru

  14. ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data

    International Nuclear Information System (INIS)

    Palmiotti, G.

    2011-01-01

    The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. The principal advances in the new library are: (1) An increase in the breadth of neutron reaction cross section coverage, extending from 393 nuclides to 418 nuclides; (2) Covariance uncertainty data for 185 of the most important nuclides, as documented in companion papers in this edition; (3) R-matrix analyses of neutron reactions on light nuclei, including isotopes of He, Li, and Be; (4) Resonance parameter analyses at lower energies and statistical high energy reactions at higher energies for isotopes of F, Cl, K, Ti, V, Mn, Cr, Ni, Zr and W; (5) Modifications to thermal neutron reactions on fission products (isotopes of Mo, Tc, Rh, Ag, Cs, Nd, Sm, Eu) and neutron absorber materials (Cd, Gd); (6) Improved minor actinide evaluations for isotopes of U, Np, Pu, and Am (we are not making changes to the major actinides 235,238U and 239Pu at this point, except for delayed neutron data, and instead we intend to update them after a further period of research in experiment and theory), and our adoption of JENDL-4.0 evaluations for isotopes of Cm, Bk, Cf, Es, Fm, and some other minor actinides; (7) Fission energy release evaluations; (8) Fission product yield advances for fission-spectrum neutrons and 14 MeV neutrons incident on 239Pu; and (9) A new Decay Data sublibrary. Integral validation testing of the ENDF/B-VII.1 library is provided for a variety of quantities: For nuclear criticality, the VII.1 library maintains the generally-good performance seen for VII.0 for a wide

  15. Fission fragment angular distributions in proton-induced fission of 209Bi (p,f) and 197Au (p,f)

    International Nuclear Information System (INIS)

    Soheily, S.; Noshad, H.; Lamehi-Rashti, M.

    2002-01-01

    The fission fragment angular distributions have been measured for proton-induced fission of 209 B i and 197 A u nuclei using surface barrier detectors at several energies between 25 MeV and 30 MeV. The experimental anisotropies are found to be in agreement with the predictions of the Standard Saddle-Point Statistical Model. The fission cross sections of 209 B i and 197 A u nuclei were also measured and compared with the previous works

  16. High-performance separation and supercritical extraction of lanthanides and actinides

    International Nuclear Information System (INIS)

    Datta, Arpita; Sujatha, K.; Kumar, R.; Sivaraman, N.; Srinivasan, T.G.; Vasudeva Rao, P.R.

    2010-01-01

    Extensive studies were carried out at Chemistry Group, IGCAR for the rapid separation of individual lanthanides and actinides using dynamic ion-exchange chromatographic technique. The atom percent fission was determined from the concentrations of the lanthanide fission products, uranium and plutonium contents of dissolver solution. These advantages were exploited to significantly reduce analysis time, liquid waste generation as well as dose to operator. Supercritical fluid extraction (SFE) of actinides from waste matrices was studied in detail at our laboratory using modified supercritical carbon dioxide (Sc-CO 2 ). Complete extraction and recovery of uranium, plutonium and americium from various matrices was achieved using Sc-CO 2 modified with suitable ligands. The technique was demonstrated for the recovery of plutonium from actual waste received from different laboratories. (author)

  17. Generalized liquid drop model and fission, fusion, alpha and cluster radioactivity and superheavy nuclei

    International Nuclear Information System (INIS)

    Royer, G.

    2012-01-01

    A particular version of the liquid drop model taking into account both the mass and charge asymmetries, the proximity energy, the rotational energy, the shell and pairing energies and the temperature has been developed to describe smoothly the transition between one and two-body shapes in entrance and exit channels of nuclear reactions. In the quasi-molecular shape valley where the proximity energy is optimized, the calculated l-dependent fusion and fission barriers, alpha and cluster radioactivity half-lives as well as actinide half-lives are in good agreement with the available experimental data. In this particular deformation path, double-humped potential barriers begin to appear even macroscopically for heavy nuclear systems due to the influence of the proximity forces and, consequently, quasi-molecular isomeric states can survive in the second minimum of the potential barriers in a large angular momentum range

  18. Calculational study for criticality safety data of fissionable actinides

    International Nuclear Information System (INIS)

    Nojiri, Ichiro; Fukasaku, Yasuhiro.

    1997-01-01

    This study has been carried out to obtain basic criticality safety characteristics of minor actinides nuclides. Criticality safety data of minor actinides nuclides have been surveyed through public literatures. Critical mass of seven nuclides, Np-237, Am-241, Am-242m, Am-243, Cm-243, Cm-244 and Cm-245, have been calculated by using two code systems of criticality safety analysis, SCALE-4 and MCNP4A, under some material and reflector conditions. Some applicable cross-section libraries have been used for each code systems. Calculated data have been compared with each other and with published data. The results of this comparison shows that there is no discrepancy within the computational codes and the calculated data is strongly depend on the cross-section library. (author)

  19. Recovery actinide values

    International Nuclear Information System (INIS)

    Horwitz, E.P.; Delphin, W.H.; Mason, G.W.

    1979-01-01

    A process is described for partitioning and recovering actinide values from acidic waste solutions resulting from reprocessing of irradiated nuclear fuels by adding hydroxylammonium nitrate and hydrazine to the waste solution to adjust the valence of the neptunium and plutonium values in the solution to the +4 oxidation state, thus forming a feed solution and contacting the feed solution with an extractant of di-hexoxyethyl phosphoric acid in an organic diluent whereby the actinide values, most of the rare earth values and some fission product values are taken up by the extractant. Separation is achieved by contacting the loaded extractant with two aqueous strip solutions, a nitric acid solution to selectively strip the americium, curium and rare earth values and an oxalate solution of tetramethylammonium hydrogen oxalate and oxalic acid or trimethylammonium hydrogen oxalate to selectively strip the neptunium, plutonium and fission product values. Uranium values remain in the extractant and may be recovered with a phosphoric acid strip. The neptunium and plutonium values are recovered from the oxalate by adding sufficient nitric acid to destroy the complexing ability of the oxalate, forming a second feed, and contacting the second feed with a second extractant of tricaprylmethylammonium nitrate in an inert diluent whereby the neptunium and plutonium values are selectively extracted. The values are recovered from the extractant with formic acid. (author)

  20. Angular distribution in the neutron-induced fission of actinides

    Directory of Open Access Journals (Sweden)

    Leong L.S.

    2013-12-01

    Full Text Available Above 1 MeV of incident neutron energy the fission fragment angular distribution (FFAD has generally a strong anisotropic behavior due to the combination of the incident orbital momentum and the intrinsic spin of the fissioning nucleus. This effect has to be taken into account for the efficiency estimation of devices used for fission cross section measurements. In addition it bears information on the spin deposition mechanism and on the structure of transitional states. We designed and constructed a detection device, based on Parallel Plate Avalanche Counters (PPAC, for measuring the fission fragment angular distributions of several isotopes, in particular 232Th. The measurement has been performed at n_TOF at CERN taking advantage of the very broad energy spectrum of the neutron beam. Fission events were recognized by back to back detection in coincidence in two position-sensitive detectors surrounding the targets. The detection efficiency, depending mostly on the stopping of fission fragments in backings and electrodes, has been computed with a Geant4 simulation and validated by the comparison to the measured case of 235U below 3 keV where the emission is isotropic. In the case of 232Th, the result is in good agreement with previous data below 10 MeV, with a good reproduction of the structures associated to vibrational states and the opening of second chance fission. In the 14 MeV region our data are much more accurate than previous ones which are broadly scattered.

  1. Prediction of fission product and actinide levels in irradiated fuel and cladding

    International Nuclear Information System (INIS)

    Burstall, R.F.; Thornton, D.E.J.

    1977-01-01

    The production of radioactive isotopes and their subsequent decay is of crucial importance in the nuclear industry, dominating the shield design of chemical reprocessing plants, transport flasks and waste disposal facilities which account for a large part of the capital investment in a nuclear programme. The isotopes are also important in studies of reactor shielding. The computation of the level and behavior of such nuclides has been practiced for many years in countries with nuclear industries, with ever-increasing sophistication in methods of calculation and in improving the accuracy of the basic nuclide data. Calculation is usually made for three groups of nuclides, the actinides or transuranics, the fission products, and nuclides present in the cladding. The currently accepted computer code within the UKAEA for such calculations is FISPIN. This code calculates activities for all the above groups either separately or in combination. As well as individual nuclide concentrations and activities integral information is produced. The paper describes the methods of calculation. The code has been compared with other codes which have a similar function, and it is concluded that the only significant differences are those associated with data. A number of different data sets, to a large degree independent, have been compared using the code, and the paper describes some of the results obtained

  2. Fusion-fission in Ar-heavy nuclei collisions

    International Nuclear Information System (INIS)

    Zaric, Alexandre

    1984-01-01

    Fusion-fission products have been studied for three reactions: Ar + Au, Ar + Bi and Ar + U (5.25-7.5 MeV/u). By measuring symmetric fragmentation components (fission-like events), cross sections for fusion were deduced and compared with the prediction of static and dynamic models. With increasing projectile energy, the width of the mass distributions strongly increases for the two lighter systems. By contrast, for Ar + U it remains essentially constant at a very large value. These results clearly demonstrate that the large increase of the width of the mass distribution cannot be attributed simply to large values of the angular momentum. However, they can be explained by the occurrence of a different dissipative process, fast fission, which can be expected if there is no barrier to fission. For the reaction Ar + Au, the total kinetic-energy distributions were also studied in detail. In this case fast fission occurs only at high incident energy. The average total kinetic energy (TKE) was found to be constant with increasing energy. (author) [fr

  3. Tip model of cold fission

    International Nuclear Information System (INIS)

    Goennenwein, F.; Boersig, B.

    1991-01-01

    Cold fission is defined to be the limiting case of nuclear fission where virtually all of the available energy is converted into the total kinetic energy of the fragments. The fragments have, therefore, to be born in or at least close to their respective ground states. Starting from the viewpoint that cold fission corresponds to most compact scission configurations, energy constraints have been exploited to calculate minimum tip distances between the two nascent fragments in binary fission. Crucial input parameters to this tip model of cold fission are the ground-state deformations of fragment nuclei. It is shown that the minimum tip distances being compatible with energy conservation vary strongly with both the mass and charge fragmentation of the fission prone nucleus. The tip distances refer to nuclei with equivalent sharp surfaces. In keeping with the size of the surface width of leptodermous nuclei, only configurations where the tip distances are smaller than a few fm may be considered as valid scission configurations. From a comparison with experimental data on cold fission this critical tip distance appears to be 3.0 fm for the model parameters chosen. Whenever the model calculation yields tip distances being smaller than the critical value, a necessary condition for attaining cold fission is considered to be fulfilled. It is shown that this criterion allows to understand in fair agreement with experiment which mass fragmentations are susceptible to lead to cold fission and which fragment-charge divisions are the most favored in each isobaric mass chain. Being based merely on energy arguments, the model cannot aim at predicting fragment yields in cold fission. However, the tip model proposed appears well suited to delineate the phase space where cold fission phenomena may come into sight. (orig.)

  4. Improved Fission Neutron Data Base for Active Interrogation of Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

    2013-11-06

    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

  5. An optimization methodology for heterogeneous minor actinides transmutation

    Science.gov (United States)

    Kooyman, Timothée; Buiron, Laurent; Rimpault, Gérald

    2018-04-01

    In the case of a closed fuel cycle, minor actinides transmutation can lead to a strong reduction in spent fuel radiotoxicity and decay heat. In the heterogeneous approach, minor actinides are loaded in dedicated targets located at the core periphery so that long-lived minor actinides undergo fission and are turned in shorter-lived fission products. However, such targets require a specific design process due to high helium production in the fuel, high flux gradient at the core periphery and low power production. Additionally, the targets are generally manufactured with a high content in minor actinides in order to compensate for the low flux level at the core periphery. This leads to negative impacts on the fuel cycle in terms of neutron source and decay heat of the irradiated targets, which penalize their handling and reprocessing. In this paper, a simplified methodology for the design of targets is coupled with a method for the optimization of transmutation which takes into account both transmutation performances and fuel cycle impacts. The uncertainties and performances of this methodology are evaluated and shown to be sufficient to carry out scoping studies. An illustration is then made by considering the use of moderating material in the targets, which has a positive impact on the minor actinides consumption but a negative impact both on fuel cycle constraints (higher decay heat and neutron) and on assembly design (higher helium production and lower fuel volume fraction). It is shown that the use of moderating material is an optimal solution of the transmutation problem with regards to consumption and fuel cycle impacts, even when taking geometrical design considerations into account.

  6. Neutron emission and fragment yield in high-energy fission

    International Nuclear Information System (INIS)

    Grudzevich, O. T.; Klinov, D. A.

    2013-01-01

    The KRIS special library of spectra and emission probabilities in the decays of 1500 nuclei excited up to energies between 150 and 250 MeV was developed for correctly taking into account the decay of highly excited nuclei appearing as fission fragments. The emission of neutrons, protons, and photons was taken into account. Neutron emission fromprimary fragments was found to have a substantial effect on the formation of yields of postneutron nuclei. The library was tested by comparing the calculated and measured yields of products originating from the fission of nuclei that was induced by high-energy protons. The method for calculating these yields was tested on the basis of experimental data on the thermal-neutroninduced fission of 235 U nuclei

  7. Actinide recycling in reactors; Aktiniden-Rezyklierung in Reaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Kuesters, H.; Wiese, H.W.; Krieg, B.

    1995-08-01

    The objective is an assessment of the transmutation of long-lived actinides and fission products and the incineration of plutonium for reducing the risk potential of radioactive waste from reactors in comparison to direct waste disposal. The contribution gives an interim account on homogeneous and heterogeneous recycling of `risk nuclides` in thermal and fast reactors. Important results: - A homogeneous 5 percent admixture of minor actinides (MA) from N4-PWRs to EFR fuel would allow a transmutation not only of the EFR MA, but in addition of the MA from 5 or 6 PWRs of equal power. However, the incineration is restricted by safety considerations. - LWR have only a very low MA incineration potential, due to their disadvantageous neutron capture/fission ratio. - In order to keep the Cm inventory at a low level, it is advantageous to concentrate the Am heterogeneously in particular fuel elements or rods. (orig./HP)

  8. Radiochemical studies of neutron deficient actinide isotopes

    International Nuclear Information System (INIS)

    Williams, K.E.

    1978-04-01

    The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, 242 Bk, was produced with a cross-section of approximately 10 μb in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, αxn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,αxn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z 1 + Z 2 = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,αxn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of 228 Pu, 230 Pu, 232 Cm, or 238 Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes

  9. Legal and regulatory issues regarding classification and disposal of wastes from actinide partitioning and transmutation

    International Nuclear Information System (INIS)

    Kocher, D.C.

    1989-01-01

    Partitioning and transmutation of actinide radioelements in spent nuclear fuel from civilian power reactors is potentially attractive because the resulting wastes might be acceptable for disposal using systems which are considerably less costly than a deep geologic repository. At present, there are no legal or regulatory prohibitions to seeking alternatives to a geologic repository for disposal of such wastes. However, additional laws and regulations would be needed, and the Nuclear Regulatory Commission has been reluctant to alter the current framework for radioactive waste management, in which geologic repositories or near-surface facilities are the only disposal options established in law and regulations unless a compelling need for alternatives with intermediate waste-isolation capabilities is demonstrated. There are also important technical considerations which are not encouraging with regard to the development of intermediate disposal systems for wastes from partitioning and transmutation of actinides in civilian spent fuel. First, the wastes may contain sufficient concentrations of fission products. Second, defense reprocessing wastes may contain sufficient concentrations of fission products and long-lived actinides. Thus, in developing the legal and regulatory framework for alternative disposal systems, there is a need to establish maximum concentrations of fission products and long-lived actinides that would be acceptable for intermediate disposal. 19 refs

  10. A new look at actinide recycle

    International Nuclear Information System (INIS)

    Burch, W.D.; Croff, A.G.; Rawlins, J.A.; Schulz, W.W.

    1991-01-01

    This paper will address the justification for reexamination of the value of recovering the minor actinides and certain fission products from spent light-water reactor fuels and describe some of the technical progress that has been made since the major studies of a decade ago. During this time, the US Environmental Protection Agency (EPA) and the Nuclear Regulatory Commission have begun establishing detailed criteria and regulations for geologic repositories. An examination of the hazards of waste disposal relative to the EPA release standards reveals that removal of 99.9% of the actinides (Pu, Am, and Np) reduces these hazards quite close to the EPA standards after 300 years' decay of the strontium and cesium. It may be also useful to remove and separately manage and dispose of certain of the long-lived fission products, such as 99 Tc and 129 I. Much additional work is required to fully assess the appropriate target recoveries as the hazards and risks are more closely examined and as the standards are reworked and refined. The two decades before the projected start of the US repository may present a window of opportunity to introduce several better management practices that act to simplify the repository safety issues. From a technical standpoint, significant progress has been made on recovery of the actinides from aqueous wastes though use of the TRUEX process. Additional work is required to demonstrate the application of the process to spent LWR fuels, but it appears straightforward. In addition, work at the Argonne National Laboratory on the liquid-metal reactor metal fuel cycle shows the relative simplicity of recycle of the actinides in that fast reactor cycle. Much work remains to fully demonstrate that actinides from all secondary waste streams can be removed to the target levels from both the aqueous reprocessing of LWR fuel and the pyro processes for the metal-fueled fast reactor. 9 refs., 2 figs

  11. Radioactive ion beams produced by neutron-induced fission at ISOLDE

    CERN Document Server

    Catherall, R; Gilardoni, S S; Köster, U

    2003-01-01

    The production rates of neutron-rich fission products for the next-generation radioactive beam facility EURISOL are mainly limited by the maximum amount of power deposited by protons in the target. An alternative approach is to use neutron beams to induce fission in actinide targets. This has the advantage of reducing: the energy deposited by the proton beam in the target; contamination from neutron-deficient isobars that would be produced by spallation; and mechanical stress on the target. At ISOLDE CERN, tests have been made on standard ISOLDE actinide targets using fast neutron bunches produced by bombarding thick, high-Z metal converters with 1 and 1.4 GeV proton pulses. This paper reviews the first applications of converters used at ISOLDE. It highlights the different geometries and the techniques used to compare fission yields produced by the proton beam directly on the target with neutron-induced fission. Results from the six targets already tested, namely UC2/graphite and ThO2 targets with tungsten an...

  12. Symmetric and asymmetric ternary fission of hot nuclei

    International Nuclear Information System (INIS)

    Siwek-Wilczynska, K.; Wilczynski, J.; Leegte, H.K.W.; Siemssen, R.H.; Wilschut, H.W.; Grotowski, K.; Panasiewicz, A.; Sosin, Z.; Wieloch, A.

    1993-01-01

    Emission of α particles accompanying fusion-fission processes in the 40 Ar + 232 Th reaction at E( 40 Ar) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight measurements allowed us to reconstruct the complete kinematics of each ternary event. The coincident energy spectra of α particles were analyzed by using predictions of the energy spectra of the statistical code CASCADE . The analysis clearly demonstrates emission from the composite system prior to fission, emission from fully accelerated fragments after fission, and also emission during scission. The analysis is presented for both symmetric and asymmetric fission. The results have been analyzed using a time-dependent statistical decay code and confronted with dynamical calculations based on a classical one-body dissipation model. The observed near-scission emission is consistent with evaporation from a dinuclear system just before scission and evaporation from separated fragments just after scission. The analysis suggests that the time scale of fission of the hot composite systems is long (about 7x10 -20 s) and the motion during the descent to scission almost completely damped

  13. Modeling level structures of odd-odd deformed nuclei

    International Nuclear Information System (INIS)

    Hoff, R.W.; Kern, J.; Piepenbring, R.; Boisson, J.P.

    1984-01-01

    A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation were derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings were used. Calculated and experimental level structures for 238 Np, 244 Am, and 250 Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Corresponding average deviations for five rare-earth nuclei are 47 keV and 7%. Several applications of this modeling technique are discussed. 18 refs., 5 figs., 4 tabs

  14. SYMMETRICAL AND ASYMMETRIC TERNARY FISSION OF HOT NUCLEI

    NARCIS (Netherlands)

    SIWEKWILCZYNSKA, K; WILCZYNSKI, J; LEEGTE, HKW; SIEMSSEN, RH; WILSCHUT, HW; GROTOWSKI, K; PANASIEWICZ, A; SOSIN, Z; WIELOCH, A

    Emission of a particles accompanying fusion-fission processes in the Ar-40 + Th-232 reaction at E(Ar-40) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight

  15. Uncertainties in fission-product decay-heat calculations

    Energy Technology Data Exchange (ETDEWEB)

    Oyamatsu, K.; Ohta, H.; Miyazono, T.; Tasaka, K. [Nagoya Univ. (Japan)

    1997-03-01

    The present precision of the aggregate decay heat calculations is studied quantitatively for 50 fissioning systems. In this evaluation, nuclear data and their uncertainty data are taken from ENDF/B-VI nuclear data library and those which are not available in this library are supplemented by a theoretical consideration. An approximate method is proposed to simplify the evaluation of the uncertainties in the aggregate decay heat calculations so that we can point out easily nuclei which cause large uncertainties in the calculated decay heat values. In this paper, we attempt to clarify the justification of the approximation which was not very clear at the early stage of the study. We find that the aggregate decay heat uncertainties for minor actinides such as Am and Cm isotopes are 3-5 times as large as those for {sup 235}U and {sup 239}Pu. The recommended values by Atomic Energy Society of Japan (AESJ) were given for 3 major fissioning systems, {sup 235}U(t), {sup 239}Pu(t) and {sup 238}U(f). The present results are consistent with the AESJ values for these systems although the two evaluations used different nuclear data libraries and approximations. Therefore, the present results can also be considered to supplement the uncertainty values for the remaining 17 fissioning systems in JNDC2, which were not treated in the AESJ evaluation. Furthermore, we attempt to list nuclear data which cause large uncertainties in decay heat calculations for the future revision of decay and yield data libraries. (author)

  16. The universal library of fission products and delayed neutron group yields

    International Nuclear Information System (INIS)

    Koldobskiy, A.B.; Zhivun, V.M.

    1997-01-01

    A new fission product yield library based on the Semiempirical method for the estimation of their mass and charge distribution is described. Contrary to other compilations, this library can be used with all possible excitation energies of fissionable actinides. The library of delayed neutron group yields, based on the fission product yield compilation, is described as well. (author). 15 refs, 4 tabs

  17. Different fission behavior induced by heavy ion central and peripheral collisions

    International Nuclear Information System (INIS)

    Wu Enjiu; Zheng Jiwen; Xiao Zhigang; Zhang Chun; Tan Jilian; Yin Shuzhi; Wang Sufang; Jin Genming; Yin Xu; Song Mingtao; Jin Weiyang; Peng Xingping; Li Zuyu; Wu Heyu; He Zhiyong; Jiang Dongxing; Qian Xing

    2000-01-01

    Correlated fission fragments from the 40 Ar + 209 Bi reaction and their further correlation with α particles have been studied for peripheral and central collisions simultaneously. The existence of different fission behavior of hot nuclei formed in central and peripheral collisions was found from the systematic analysis of the mass and energy distributions of fission fragments as a function of the initial temperature of hot fissioning nuclei

  18. Axisymmetric Magnetic Mirror Fusion-Fission Hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Moir, R. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martovetsky, N. N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Molvik, A. W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simonen, T. C. [Univ. of California, Berkeley, CA (United States)

    2011-05-13

    The achieved performance of the gas dynamic trap version of magnetic mirrors and today’s technology we believe are sufficient with modest further efforts for a neutron source for material testing (Q=Pfusion/Pinput~0.1). The performance needed for commercial power production requires considerable further advances to achieve the necessary high Q>>10. An early application of the mirror, requiring intermediate performance and intermediate values of Q~1 are the hybrid applications. The Axisymmetric Mirror has a number of attractive features as a driver for a fusion-fission hybrid system: geometrical simplicity, inherently steady-state operation, and the presence of the natural divertors in the form of end tanks. This level of physics performance has the virtue of low risk and only modest R&D needed and its simplicity promises economy advantages. Operation at Q~1 allows for relatively low electron temperatures, in the range of 4 keV, for the DT injection energy ~ 80 keV. A simple mirror with the plasma diameter of 1 m and mirror-to-mirror length of 35 m is discussed. Simple circular superconducting coils are based on today’s technology. The positive ion neutral beams are similar to existing units but designed for steady state. A brief qualitative discussion of three groups of physics issues is presented: axial heat loss, MHD stability in the axisymmetric geometry, microstability of sloshing ions. Burning fission reactor wastes by fissioning actinides (transuranics: Pu, Np, Am, Cm, .. or just minor actinides: Np, Am, Cm, …) in the hybrid will multiply fusion’s energy by a factor of ~10 or more and diminish the Q needed to less than 1 to overcome the cost of recirculating power for good economics. The economic value of destroying actinides by fissioning is rather low based on either the cost of long-term storage or even deep geologic disposal so most of the revenues of hybrids will come from electrical power. Hybrids that obtain revenues from

  19. ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M. B. [Los Alamos National Laboratory (LANL); Herman, Micheal W [Brookhaven National Laboratory (BNL); Oblozinsky, Pavel [Brookhaven National Laboratory (BNL); Dunn, Michael E [ORNL; Danon, Y. [Rensselaer Polytechnic Institute (RPI); Kahler, A. [Los Alamos National Laboratory (LANL); Smith, Donald L. [Argonne National Laboratory (ANL); Pritychenko, B [Brookhaven National Laboratory (BNL); Arbanas, Goran [ORNL; Arcilla, r [Brookhaven National Laboratory (BNL); Brewer, R [Los Alamos National Laboratory (LANL); Brown, D A [Brookhaven National Laboratory (BNL); Capote, R. [International Atomic Energy Agency (IAEA); Carlson, A. D. [National Institute of Standards and Technology (NIST); Cho, Y S [Korea Atomic Energy Research Institute; Derrien, Herve [ORNL; Guber, Klaus H [ORNL; Hale, G. M. [Los Alamos National Laboratory (LANL); Hoblit, S [Brookhaven National Laboratory (BNL); Holloway, Shannon T. [Los Alamos National Laboratory (LANL); Johnson, T D [Brookhaven National Laboratory (BNL); Kawano, T. [Los Alamos National Laboratory (LANL); Kiedrowski, B C [Los Alamos National Laboratory (LANL); Kim, H [Korea Atomic Energy Research Institute; Kunieda, S [Los Alamos National Laboratory (LANL); Larson, Nancy M [ORNL; Leal, Luiz C [ORNL; Lestone, J P [Los Alamos National Laboratory (LANL); Little, R C [Los Alamos National Laboratory (LANL); Mccutchan, E A [Brookhaven National Laboratory (BNL); Macfarlane, R E [Los Alamos National Laboratory (LANL); MacInnes, M [Los Alamos National Laboratory (LANL); Matton, C M [Lawrence Livermore National Laboratory (LLNL); Mcknight, R D [Argonne National Laboratory (ANL); Mughabghab, S F [Brookhaven National Laboratory (BNL); Nobre, G P [Brookhaven National Laboratory (BNL); Palmiotti, G [Idaho National Laboratory (INL); Palumbo, A [Brookhaven National Laboratory (BNL); Pigni, Marco T [ORNL; Pronyaev, V. G. [Institute of Physics and Power Engineering (IPPE), Obninsk, Russia; Sayer, Royce O [ORNL; Sonzogni, A A [Brookhaven National Laboratory (BNL); Summers, N C [Lawrence Livermore National Laboratory (LLNL); Talou, P [Los Alamos National Laboratory (LANL); Thompson, I J [Lawrence Livermore National Laboratory (LLNL); Trkov, A. [Jozef Stefan Institute, Slovenia; Vogt, R L [Lawrence Livermore National Laboratory (LLNL); Van der Marck, S S [Nucl Res & Consultancy Grp, Petten, Netherlands; Wallner, A [University of Vienna, Austria; White, M C [Los Alamos National Laboratory (LANL); Wiarda, Dorothea [ORNL; Young, P C [Los Alamos National Laboratory (LANL)

    2011-01-01

    The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. The principal advances in the new library are: (1) An increase in the breadth of neutron reaction cross section coverage, extending from 393 nuclides to 423 nuclides; (2) Covariance uncertainty data for 190 of the most important nuclides, as documented in companion papers in this edition; (3) R-matrix analyses of neutron reactions on light nuclei, including isotopes of He; Li, and Be; (4) Resonance parameter analyses at lower energies and statistical high energy reactions for isotopes of Cl; K; Ti, V, Mn, Cr, Ni, Zr and W; (5) Modifications to thermal neutron reactions on fission products (isotopes of Mo, Tc, Rh, Ag, Cs, Nd, Sm, Eu) and neutron absorber materials (Cd, Gd); (6) Improved minor actinide evaluations for isotopes of U, Np, Pu, and Am (we are not making changes to the major actinides (235,238)U and (239)Pu at this point, except for delayed neutron data and covariances, and instead we intend to update them after a further period of research in experiment and theory), and our adoption of JENDL-4.0 evaluations for isotopes of Cm, Bk, Cf, Es; Fm; and some other minor actinides; (7) Fission energy release evaluations; (8) Fission product yield advances for fission-spectrum neutrons and 14 MeV neutrons incident on (239)Pu; and (9) A new decay data sublibrary. Integral validation testing of the ENDF/B-VII.1 library is provided for a variety of quantities: For nuclear criticality, the VII.1 library maintains the generally-good performance seen for VII.0 for a wide

  20. Identification of new neutron-rich rare-earth nuclei produced in /sup 252/Cf spontaneous fission

    CERN Document Server

    Greenwood, R C; Gehrke, R J; Meikrantz, D H

    1981-01-01

    A program of systematic study of the decay properties of neutron-rich rare-earth nuclei with 30 sfission, is currently underway using the Idaho ESOL (Elemental Separation On Line) Facility. The chemistry system used for the rare-earth elemental separations consists of two high-performance chromatography columns connected in series and coupled to the /sup 252 /Cf fission source via a helium gas-jet transport arrangement. The time delay for separation and initiation of gamma -ray counting with results which have been obtained to date with this system include the identification of a number of new neutron-rich rare-earth isotopes including /sup 155/Pm (t/sub 1/2/=48+or-4 s) and /sup 163/Gd (t/sub 1 /2/=68+or-3 s), in addition to 5.51 min /sup 158/Sm which was identified in an earlier series of experiments. (11 refs).

  1. Fast electric dipole transitions in Ra-Ac nuclei

    International Nuclear Information System (INIS)

    Ahmad, I.

    1985-01-01

    Lifetime of levels in 225 Ra, 225 Ac, and 227 Ac have been measured by delayed coincidence techniques and these have been used to determine the E1 gamma-ray transition probabilities. The reduced E1 transition probabilities. The reduced E1 transition probabilities in 225 Ra and 225 Ac are about two orders of magnitude larger than the values in mid-actinide nuclei. On the other hand, the E1 rate in 227 Ac is similar to those measured in heavier actinides. Previous studies suggest the presence of octupole deformation in all the three nuclei. The present investigation indicates that fast E1 transitions occur for nuclei with octupole deformation. However, the studies also show that there is no one-to-one correspondence between E1 rate and octupole deformation. 13 refs., 4 figs

  2. Radiochemical studies of neutron deficient actinide isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K.E.

    1978-04-01

    The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, /sup 242/Bk, was produced with a cross-section of approximately 10 ..mu..b in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, ..cap alpha..xn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,..cap alpha..xn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z/sub 1/ + Z/sub 2/ = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,..cap alpha..xn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of /sup 228/Pu, /sup 230/Pu, /sup 232/Cm, or /sup 238/Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes.

  3. A revised calculational model for fission

    Energy Technology Data Exchange (ETDEWEB)

    Atchison, F

    1998-09-01

    A semi-empirical parametrization has been developed to calculate the fission contribution to evaporative de-excitation of nuclei with a very wide range of charge, mass and excitation-energy and also the nuclear states of the scission products. The calculational model reproduces measured values (cross-sections, mass distributions, etc.) for a wide range of fissioning systems: Nuclei from Ta to Cf, interactions involving nucleons up to medium energy and light ions. (author)

  4. Advanced Aqueous Separation Systems for Actinide Partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Ken [Washington State Univ., Pullman, WA (United States); Martin, Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lumetta, Gregg [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-04-02

    One of the most challenging aspects of advanced processing of used nuclear fuel is the separation of transplutonium actinides from fission product lanthanides. This separation is essential if actinide transmutation options are to be pursued in advanced fuel cycles, as lanthanides compete with actinides for neutrons in both thermal and fast reactors, thus limiting efficiency. The separation is difficult because the chemistry of Am3+ and Cm3+ is nearly identical to that of the trivalent lanthanides (Ln3+). The prior literature teaches that two approaches offer the greatest probability of devising a successful group separation process based on aqueous processes: 1) the application of complexing agents containing ligand donor atoms that are softer than oxygen (N, S, Cl-) or 2) changing the oxidation state of Am to the IV, V, or VI state to increase the essential differences between Am and lanthanide chemistry (an approach utilized in the PUREX process to selectively remove Pu4+ and UO22+ from fission products). The latter approach offers the additional benefit of enabling a separation of Am from Cm, as Cm(III) is resistant to oxidation and so can easily be made to follow the lanthanides. The fundamental limitations of these approaches are that 1) the soft(er) donor atoms that interact more strongly with actinide cations than lanthanides form substantially weaker bonds than oxygen atoms, thus necessitating modification of extraction conditions for adequate phase transfer efficiency, 2) soft donor reagents have been seen to suffer slow phase transfer kinetics and hydro-/radiolytic stability limitations and 3) the upper oxidation states of Am are all moderately strong oxidants, hence of only transient stability in media representative of conventional aqueous separations systems. There are examples in the literature of both approaches having been described. However, it is not clear at present that any extant process is sufficiently robust for application at the scale

  5. Review of fission-fusion pellet designs and inertial confinement system studies at EIR

    Energy Technology Data Exchange (ETDEWEB)

    Seifriz, W [Eidgenoessisches Inst. fuer Reaktorforschung, Wuerenlingen (Switzerland)

    1978-01-01

    The article summarizes the work done so far at the Swiss Federal Institute for Reactor Research (EIR) in the field of the inertial confinement fusion technique. The following subjects are reviewed: a) fission fusion pellet designs using fissionable triggers, b) uranium tampered pellets, c) tampered pellets recycling unwanted actinide wastes from fission reactors in beam-driven micro-explosion reactors, and d) symbiotic fusion/fission reactor studies.

  6. Evaluations of fusion-fission (hybrid) concepts: market penetration analysis for fusion-fission hybrids. Part A

    International Nuclear Information System (INIS)

    Engel, R.L.; Deonigi, D.E.

    1976-01-01

    This report summarizes findings of the fusion-fission studies conducted for the Electric Power Research Institute by Battelle, Pacific Northwest Laboratories. This particular study focused on the evaluation of fissile material producing hybrids. Technical results of the evaluation of actinide burning are presented in a companion volume, Part B

  7. Shell effects in fission and quasi-fission of heavy and superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Itkis, M.G. E-mail: itkis@flnr.jinr.ru; Aeystoe, J.; Beghini, S.; Bogachev, A.A.; Corradi, L.; Dorvaux, O.; Gadea, A.; Giardina, G.; Hanappe, F.; Itkis, I.M.; Jandel, M.; Kliman, J.; Khlebnikov, S.V.; Kniajeva, G.N.; Kondratiev, N.A.; Kozulin, E.M.; Krupa, L.; Latina, A.; Materna, T.; Montagnoli, G.; Oganessian, Yu.Ts.; Pokrovsky, I.V.; Prokhorova, E.V.; Rowley, N.; Rubchenya, V.A.; Rusanov, A.Ya.; Sagaidak, R.N.; Scarlassara, F.; Stefanini, A.M.; Stuttge, L.; Szilner, S.; Trotta, M.; Trzaska, W.H.; Vakhtin, D.N.; Vinodkumar, A.M.; Voskressenski, V.M.; Zagrebaev, V.I

    2004-04-05

    Results of the experiments aimed at the study of fission and quasi-fission processes in the reactions {sup 12}C+{sup 204}Pb, {sup 48}Ca+{sup 144,154}Sm, {sup 168}Er, {sup 208}Pb, {sup 244}Pu, {sup 248}Cm; {sup 58}Fe+{sup 208}Pb, {sup 244}Pu, {sup 248}Cm, and {sup 64}Ni+{sup 186}W, {sup 242}Pu are presented in the work. The choice of the above-mentioned reactions was inspired by recent experiments on the production of the isotopes {sup 283}112, {sup 289}114 and {sup 283}116 at Dubna [1],[2] using the same reactions. The {sup 58}Fe and {sup 64}Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) and the Accelerator of the Laboratory of University of Jyvaskyla (JYFL, Finland) using the time-of-flight spectrometer of fission fragments CORSET[3] and the neutron multi-detector DEMON[4],[5]. The role of shell effects and the influence of the entrance channel on the mechanism of the compound nucleus fusion-fission and the competitive process of quasi-fission are discussed.

  8. Fission dynamics in the proton induced fission of heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Rubchenya, V.A. E-mail: rubchen@phys.jyu.fi; Trzaska, W.H.; Itkis, I.M.; Itkis, M.G.; Kliman, J.; Kniajeva, G.N.; Kondratiev, N.A.; Kozulin, E.M.; Krupa, L.; Pokrovski, I.V.; Voskressenski, V.M.; Hanappe, F.; Materna, T.; Dorvaux, O.; Stuttge, L.; Chubarian, G.; Khlebnikov, S.V.; Vakhtin, D.N.; Lyapin, V.G

    2004-04-05

    Multi-parameter correlation study of the reaction {sup 242}Pu(p, f) at E{sub p} 13, 20 and 55 MeV has been carried out. Fission fragment mass and kinetic energy distributions and the double differential neutron spectra have been measured. It was observed that the two-humped shape of mass distributions prevailed up to highest proton energy. Manifestation of the nuclear shell Z 28 near fragment mass A{sub fr} = 70 has been detected. The experimental results were analyzed in the framework of a time-dependent statistical model with inclusion of nuclear friction effects in the fission process. The multi-parameter correlation study of the reaction.

  9. Statistical fission parameters for nuclei at high excitation and angular momenta

    International Nuclear Information System (INIS)

    Blann, M.; Komoto, T.A.

    1982-01-01

    Experimental fusion/fission excitation functions are analyzed by the statistical model with modified rotating liquid drop model barriers and with single particle level densities modeled for deformation for ground state (a/sub ν/) and saddle point nuclei (a/sub f/). Values are estimated for the errors in rotating liquid drop model barriers for the different systems analyzed. These results are found to correlate well with the trends predicted by the finite range model of Krappe, Nix, and Sierk, although the discrepancies seem to be approximately 1 MeV greater than the finite range model predictions over the limited range tested. The a priori values calculated for a/sub f/ and a/sub ν/ are within +- 2% of optimum free parameter values. Analyses for barrier decrements explore the importance of collective enhancement on level densities and of nuclear deformation in calculating transmission coefficients. A calculation is performed for the 97 Rh nucleus for which a first order angular momentum scaling is used for the J = 0 finite range corrections. An excellent fit is found for the fission excitation function in this approach. Results are compared in which rotating liquid drop model barriers are decremented by a constant energy, or alternatively multiplied by a constant factor. Either parametrization is shown to be capable of satisfactorily reproducing the data although their J = 0 extrapolated values differ markedly from one another. This underscores the dangers inherent in arbitrary barrier extrapolations

  10. Analysis of the Gas Core Actinide Transmutation Reactor (GCATR)

    Science.gov (United States)

    Clement, J. D.; Rust, J. H.

    1977-01-01

    Design power plant studies were carried out for two applications of the plasma core reactor: (1) As a breeder reactor, (2) As a reactor able to transmute actinides effectively. In addition to the above applications the reactor produced electrical power with a high efficiency. A reactor subsystem was designed for each of the two applications. For the breeder reactor, neutronics calculations were carried out for a U-233 plasma core with a molten salt breeding blanket. A reactor was designed with a low critical mass (less than a few hundred kilograms U-233) and a breeding ratio of 1.01. The plasma core actinide transmutation reactor was designed to transmute the nuclear waste from conventional LWR's. The spent fuel is reprocessed during which 100% of Np, Am, Cm, and higher actinides are separated from the other components. These actinides are then manufactured as oxides into zirconium clad fuel rods and charged as fuel assemblies in the reflector region of the plasma core actinide transmutation reactor. In the equilibrium cycle, about 7% of the actinides are directly fissioned away, while about 31% are removed by reprocessing.

  11. Relativistic Coulomb Fission

    Science.gov (United States)

    Norbury, John W.

    1992-01-01

    Nuclear fission reactions induced by the electromagnetic field of relativistic nuclei are studied for energies relevant to present and future relativistic heavy ion accelerators. Cross sections are calculated for U-238 and Pu-239 fission induced by C-12, Si-28, Au-197, and U-238 projectiles. It is found that some of the cross sections can exceed 10 b.

  12. On the influence of the americium isotopic vector on the cooling time of minor actinides bearing blankets in fast reactors

    Directory of Open Access Journals (Sweden)

    Kooyman Timothée

    2018-01-01

    Full Text Available In the heterogeneous minor actinides transmutation approach, the nuclei to be transmuted are loaded in dedicated targets often located at the core periphery, so that long-lived heavy nuclides are turned into shorter-lived fission products by fission. To compensate for low flux level at the core periphery, the minor actinides content in the targets is set relatively high (around 20 at.%, which has a negative impact on the reprocessing of the targets due to their important decay heat level. After a complete analysis of the main contributors to the heat load of the irradiated targets, it is shown here that the choice of the reprocessing order of the various feeds of americium from the fuel cycle depends on the actual limit for fuel reprocessing. If reprocessing of hot targets is possible, it is more interesting to reprocess first the americium feed with a high 243Am content in order to limit the total cooling time of the targets, while if reprocessing of targets is limited by their decay heat, it is more interesting to wait for an increase in the 241Am content before loading the americium in the core. An optimization of the reprocessing order appears to lead to a decrease of the total cooling time by 15 years compared to a situation where all the americium feeds are mixed together when two feeds from SFR are considered with a high reprocessing limit.

  13. Fission product margin in burnup credit analyses

    International Nuclear Information System (INIS)

    Finck, P.J.; Stenberg, C.G.

    1998-01-01

    The US Department of Energy (DOE) is currently working toward the licensing of a methodology for using actinide-only burnup credit for the transportation of spent nuclear fuel (SNF). Important margins are built into this methodology. By using comparisons with a representative experimental database to determine bias factors, the methodology ensures that actinide concentrations and worths are estimated conservatively; furthermore, the negative net reactivity of certain actinides and all fission products (FPs) is not taken into account, thus providing additional margin. A future step of DOE's effort might aim at establishing an actinide and FP burnup credit methodology. The objective of this work is to establish the uncertainty to be applied to the total FP worth in SNF. This will serve two ends. First, it will support the current actinide-only methodology by demonstrating the margin available from FPs. Second, it will identify the major contributions to the uncertainty and help set priorities for future work

  14. Casting of metallic fuel containing minor actinide additions

    International Nuclear Information System (INIS)

    Trybus, C.L.; Henslee, S.P.; Sanecki, J.E.

    1992-01-01

    A significant attribute of the Integral Fast Reactor (IFR) concept is the transmutation of long-lived minor actinide fission products. These isotopes require isolation for thousands of years, and if they could be removed from the waste, disposal problems would be reduced. The IFR utilizes pyroprocessing of metallic fuel to separate auranium, plutonium, and the minor actinides from nonfissionable constituents. These materials are reintroduced into the fuel and reirradiated. Spent IFR fuel is expected to contain low levels of americium, neptunium, and curium because the hard neutron spectrum should transmute these isotopes as they are produced. This opens the possibility of using an IFR to trnasmute minor actinide waste from conventional light water reactors (LWRs). A standard IFR fuel is based on the alloy U-20% Pu-10% Zr (in weight percent). A metallic fuel system eases the requirements for reprocessing methods and enables the minor actinide metals to be incorporated into the fuel with simple modifications to the basic fuel casting process. In this paper, the authors report the initial casting experience with minor actinide element addition to an IFR U-Pu-Zr metallic fuel

  15. Fusion-fission dynamics and perspectives of future experiments

    International Nuclear Information System (INIS)

    Zagrebaev, V.I.; Itkis, M.G.; Oganessian, Yu.Ts.

    2003-01-01

    The paper is focused on reaction dynamics of superheavy-nucleus formation and decay at beam energies near the Coulomb barrier. The aim is to review the things we have learned from recent experiments on fusion-fission reactions leading to the formation of compound nuclei with Z ≥ 102 and from their extensive theoretical analysis. Major attention is paid to the dynamics of formation of very heavy compound nuclei taking place in strong competition with the process of fast fission (quasifission). The choice of collective degrees of freedom playing a fundamental role and finding the multidimensional driving potential and the corresponding dynamic equation regulating the whole process are discussed. A possibility of deriving the fission barriers of superheavy nuclei directly from performed experiments is of particular interest here. In conclusion, the results of a detailed theoretical analysis of available experimental data on the 'cold' and 'hot' fusion-fission reactions are presented. Perspectives of future experiments are discussed along with additional theoretical studies in this field needed for deeper understanding of the fusion-fission processes of very heavy nuclear systems

  16. The status of fission product yield data (FPND) in 1977

    International Nuclear Information System (INIS)

    Cuninghame, J.G.

    1977-05-01

    The topics covered is this paper are:- (a) cumulative yields in thermal neutron fission and in fast fission up to 14 MeV incident neutron energy; (b) dependence of the yields on incident neutron energy and spectrum; (c) independent yields; (d) charge dispersion and distribution, and (e) yields of light particles from ternary fission. The paper reviews information on these subjects for fission of actinides from 232 Th upwards, with special emphasis on data published since the 1973 Bologna FPND Panel, compares data sets and discusses the gaps still to be found in them. (author)

  17. Actinide targets for fundamental research in nuclear physics

    Science.gov (United States)

    Eberhardt, K.; Düllmann, Ch. E.; Haas, R.; Mokry, Ch.; Runke, J.; Thörle-Pospiech, P.; Trautmann, N.

    2018-05-01

    Thin actinide layers deposited on various substrates are widely used as calibration sources in nuclear spectroscopy. Other applications include fundamental research in nuclear chemistry and -physics, e.g., the chemical and physical properties of super-heavy elements (SHE, Z > 103) or nuclear reaction studies with heavy ions. For the design of future nuclear reactors like fast-fission reactors and accelerator-driven systems for transmutation of nuclear waste, precise data for neutron absorption as well as neutron-induced fission cross section data for 242Pu with neutrons of different energies are of particular importance, requiring suitable Pu-targets. Another application includes studies of nuclear transitions in 229Th harvested as α-decay recoil product from a thin layer of its 233U precursor. For this, a thin and very smooth layer of 233U is used. We report here on the production of actinide layers mostly obtained by Molecular Plating (MP). MP is currently the only fabrication method in cases where the desired actinide material is available only in very limited amounts or possesses a high specific activity. Here, deposition is performed from organic solution applying a current density of 1-2 mA/cm2. Under these conditions target thicknesses of 500-1000 μg/cm2 are possible applying a single deposition step with deposition yields approaching 100 %. For yield determination α-particle spectroscopy, γ-spectroscopy and Neutron Activation Analysis is routinely used. Layer homogeneity is checked with Radiographic Imaging. As an alternative technique to MP the production of thin lanthanide and actinide layers by the so-called "Drop on Demand"-technique applied e.g., in ink-jet printing is currently under investigation.

  18. Fission properties of the heaviest elements

    International Nuclear Information System (INIS)

    Moller, P.; Nix, R.

    1995-01-01

    The authors discuss fission properties of the heaviest elements. In particular they focus on stability with respect to spontaneous fission and on the prospects of extending the region of known nuclei beyond the peninsula of currently known nuclides

  19. Gyromagnetic factors for high spin states in the actinides

    International Nuclear Information System (INIS)

    Ring, P.

    1984-01-01

    The cranked Hartree-Fock-Bogoliubov theory was used for a systematic investigation of gyromagnetic factors in the yrast states of even-even actinide nuclei. The theory used was the most simplified version with fixed deformation and gap parameters, that is, so-called rotating shell model. The gyromagnetic factor g and the contribution gsub(p) and gsub(n) were obtained for a large number of nuclei in the actinide region. The aligned angular momenta for protons and for neutrons are shown in the same actinide region. The general behaviour of g-factor was able to be understood in terms of simple rules: (i) For fixed proton number, neutron alignment becomes more difficult with increasing the neutron number, and vice versa. (ii) A sudden neutron alignment was observed for N=140 and N=146, and a sudden proton alignment was also observed for Z=94. The alignment between these critical numbers was smooth. The pattern obtained for the values of the aligned angular momentum was clearly reflected to the g-factor, and it provided an excellent tool to study the structure of level in the high spin region. (Asami, T.)

  20. The cross section sensitivity of the minor actinides on a lead-bismuth cooled accelerator-driven burner system

    International Nuclear Information System (INIS)

    Gil, Choong-Sup; Kim, Jung-Do; Chang, Jonghwa

    2002-01-01

    In order to validate the detailed sensitivity of each minor actinide datum in ENDF/B-VI Release 6, JEF-2.2 and JENDL-3.2 on an accelerator-driven minor actinide burner benchmark system, a lead-bismuth cooled sub-critical system was analyzed. The impacts on the system by the ten minor actinides were compared. The k eff values and reaction rates were calculated by exchanging the data sets of each minor actinide from ENDF/B-VI.6 to JEF-2.2 or JENDL-3.2. At the equilibrium core, the k eff differences from ENDF/B-VI.6 by the ten minor actinides can cause more than 5,500 pcm for JEF-2.2 and 3,500 pcm for JENDL-3.2. The fission reaction rates of 242m Am and 243 Cm with ENDF/B-VI.6 show differences of more than 15% from those with JEF-2.2 and JENDL-3.2. 241 Am, 243 Am and 245 Cm in JEF-2.2 and americium isotope data and 245 Cm in JENDL-3.2 are sensitive to the fission spectrum. (author)

  1. Physics and chemistry of fission

    International Nuclear Information System (INIS)

    1979-01-01

    Full text: In the pleasant and hospitable atmosphere of the Kernforschungsanlage Juelich in the Federal Republic of Germany, the IAEA symposium on the Physics and Chemistry of Fission took place. Almost 200 scientists attended, 154 abstracts were submitted, and 57 papers presented, but more important than the numbers was the quality of the contributions and the progress reported at the symposium. The neutron was discovered almost 50 years ago; 40 years ago the idea of nuclear fission was born. Since then, a number of laboratories have worked hard to explain the phenomenon of fission One would expect that by now scientists would know exactly what happens in a nucleus before and during the process of fission, particularly as there are hundreds of power and research reactors in operation, and fission of uranium isotopes is the basis of their functioning. At first glance, fission seems a simple process: a neutron hits and penetrates the uranium nucleus which becomes excited, i.e. has a surplus of energy. One way to get rid of this energy is for the nucleus to split into two parts; additional products of this process are energy and more neutrons. Nature, however, seems to dislike such straightforward explanations. In the case of fission, scientists have observed a number of phenomena which disagree with a simple model. Sometimes, a nucleus will split into two parts without being 'attacked' by a neutron; this spontaneous fission opens up a new line of fission research and several contributions at the symposium reported on sophisticated experiments designed to unravel some of its specific details. Sometimes, a fissioning nucleus will emit another particle: ternary fission has become a powerful tool for studying the properties of nuclei during the fission process. For the scientist, it is fascinating to observe how the nucleus behaves during fission. They invent models which are supposed to reproduce the most probable course of events leading to fission. In one of these

  2. Monazite as a suitable actinide waste form

    Energy Technology Data Exchange (ETDEWEB)

    Schlenz, Hartmut; Heuser, Julia; Schmitz, Stephan; Bosbach, Dirk [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); Neumann, Andreas [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); RWTH Aachen Univ. (Germany). Inst. for Crystallography

    2013-03-01

    The conditioning of radioactive waste from nuclear power plants and in some countries even of weapons plutonium is an important issue for science and society. Therefore the research on appropriate matrices for the immobilization of fission products and actinides is of great interest. Beyond the widely used borosilicate glasses, ceramics are promising materials for the conditioning of actinides like U, Np, Pu, Am, and Cm. Monazite-type ceramics with general composition LnPO{sub 4} (Ln = La to Gd) and solid solutions of monazite with cheralite or huttonite represent important materials in this field. Monazite appears to be a promising candidate material, especially because of its outstanding properties regarding radiation resistance and chemical durability. This article summarizes the most recent results concerning the characterization of monazite and respective solid solutions and the study of their chemical, thermal, physical and structural properties. The aim is to demonstrate the suitability of monazite as a secure and reliable waste form for actinides. (orig.)

  3. Heavy ion induced fission between 10 and 100 MeV/u

    International Nuclear Information System (INIS)

    Steckmeyer, J.C.; Tamain, B.

    1986-05-01

    Heavy ion induced fission between 10 and 100 MeV/u is discussed. It is shown that one can obtain information on fusion limits and on typical times characterizing nuclear matter. Intermediate energy heavy ions can be used to build very excited fusion nuclei. Section I shows that fission can then be used as a tool to test the fusion mechanism and to discover what are the extreme limits concerning fusion and hot nuclei formation. In section II, it is shown that when very hot nuclei are built, fission evaporation competition cannot any longer be fully described in the usual way by the statistical model. New features as dynamical aspects or cluster evaporation modify dramatically the landscape. Concerning the detailed fission properties of very hot nuclei (for instance fragments properties), no strong deviations from the already know systematics has been obtained. However, very few detailed studies are yet available and a clear experimental program has to be developed in order to progress. From a theoretical point of view, it is rather necessary to described fission and evaporation is an unified way

  4. Phoenix type concepts for transmutation of LWR waste minor actinides

    International Nuclear Information System (INIS)

    Segev, M.

    1994-01-01

    A number of variations on the original Phoenix theme were studied. The basic rationale of the Phoenix incinerator is making oxide fuel of the LWR waste minor actinides, loading it in an FFTF-like subcritical core, then bombarding the core with the high current beam accelerated protons to generate considerable energy through spallation and fission reactions. As originally assessed, if the machine is fed with 1600 MeV protons in a 102 mA current, then 8 core modules are driven to transmute the yearly minor actinides waste of 75 1000 MW LWRs into Pu 238 and fission products; in a 2 years cycle the energy extracted is 100000 MW d/T. This performance cannot be substantiated in a rigorous analysis. A calculational consistent methodology, based on a combined execution of the Hermes, NCNP, and Korigen codes, shows, nonetheless that changes in the original Phoenix parameters can upgrade its performance.The original Phoenix contains 26 tons minor actinides in 8 core modules; 1.15 m 3 module is shaped for 40% neutron leakage; with a beam of 102 mA the 8 modules are driven to 100000 MW/T in 10.5 years, burning out the yearly minor actinide waste of 15 LWRs; the operation must be assisted by grid electricity. If the 1.15 m 3 module is shaped to allow only 28% leakage, then a beam of 102 mA will drive the 8 modules to 100000 MW/T in 3.5 years, burning out the yearly minor actinides waste of 45 LWRs. Some net grid electricity will be generated. If 25 tons minor actinides are loaded into 5 modules, each 1.72 m 3 in volume and of 24% leakage, then a 97 mA beam will drive the module to 100000 MW/T in 2.5 years, burning out the yearly minor actinides waste of 70 LWRs. A considerable amount of net grid electricity will be generated. If the lattice is made of metal fuel, and 26 tons minor actinides are loaded into 32 small modules, 0.17 m 3 each, then a 102 mA beam will drive the modules to 100000 MW/T in 2 years, burning out the yearly minor actinides waste of 72 LWRs. A considerable

  5. Measurement of Fission Fragment Angular Distributions for 14 N+ 232 Th and 11 B+ 235 U at Near-Barrier Energies

    International Nuclear Information System (INIS)

    Behera, B.R.; Jena, S.; Satapathy, M.; Ison, V.V.; Kailas, S.; Chatterjee, A.; Shrivastava, A.; Mahata, K.; Satpathy, L.; Basu, P.; Roy, S.; Sharan, M.; Chatterjee, M.L; Datta, S.K.

    2000-01-01

    Fission fragment angular distributions of heavy-ion induced fission in actinide nuclei at near-barrier energies show anomalous fragment anisotropies. At above barrier energies entrance channel dependence is a probable cause and explanation in terms of pre-equilibrium fission and the critical mass asymmetry parameter (Businaro-Gallone) has been tried. Target deformation and ground state spin also seem to influence the measured anisotropy. To understand the extent of importance of some or all of these features, we performed a set of experiments where (i) entrance channel dependence (ii) mass asymmetry on the two sides of Businaro-Gallone and (iii) different ground state spins are present. The channels chosen are 14 N+ 232 Th and 11 B+ 235 U. Experiments were done using the Pelletron accelerators at NSC, New Delhi and BARC-TIFR, Bombay. Compound nucleus populated in both cases is 246 Bk. 232 Th has ground state spin zero and 235 U has spin 7/2. Fragment anisotropies have been measured from 10-15 % above barrier to 10 % below barrier at similar excitation energy (around 40 MeV to 58 MeV). The mean square angular momentum is matched at least at one energy. Results indicate that when both excitation energy and angular momentum are matched, there are differences in the measured values of fission anisotropies. This implies entrance channel dependence consistent with the expectation of pre-equilibrium fission model. (authors)

  6. Stability of superheavy nuclei

    Science.gov (United States)

    Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.

    2018-03-01

    The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92 ≤Z ≤126 and isospins 40 ≤N -Z ≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N . α -decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted.

  7. Conceptual design of a fusion-fission hybrid reactor for transmutation of high level nuclear waste

    International Nuclear Information System (INIS)

    Qiu, L.J.; Wu, Y.C.; Yang, Y.W.; Wu, Y.; Luan, G.S.; Xu, Q.; Guo, Z.J.; Xiao, B.J.

    1994-01-01

    To assess the feasibility of the transmutation of long-lived radioactive waste using fusion-fission hybrid reactors, we are studying all the possible types of blanket, including a comparison of the thermal and fast neutron spectrum blankets. Conceptual designs of a small tokamak hybrid blanket with small inventory of actinides and fission products are presented. The small inventory of wastes makes the system safer. The small hybrid reactor system based on a fusion core with experimental parameters to be realized in the near future can effectively transmute actinides and fission products at a neutron wall loading of 1MWm -2 . An innovative energy system is also presented, including a fusion driver, fuel breeder, high level waste transmuter, fission reactor and so on. An optimal combination of all types of reactor is proposed in the system. ((orig.))

  8. Statistical model calculations with a double-humped fission barrier GIVAB computer code

    International Nuclear Information System (INIS)

    Delagrange, H.; Gilat, J.

    1979-01-01

    Neutron and gamma emission probabilities and fission probabilities are computed, taking into account the special feature of the actinide fission barriers with two maxima. Spectra and cross sections are directly deduced from these probabilities. Populations of both wells are followed step by step. For each initial E and J, decay rates are computed and normalized in order to obtain the de-excitation probabilities imposed by the two-humped fission barrier

  9. ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M.B.; Herman, M.; Author(s): Chadwick,M.B.; Herman,M.; Oblozinsky,P.; Dunn,M.E.; Danon,Y.; Kahler,A.C.; Smith,D.L.; Pritychenko,B.; Arbanas,G.; Arcilla,R.; Brewer,R.; Brown,D.A.; Capote,R.; Carlson,A.D.; Cho,Y.S.; Derrien,H.; Guber,K.; Hale,G.M.; Hoblit,S.; Holloway,S.: Johnson,T.D.; Kawano,T.; Kiedrowski,B.C.; Kim,H.; Kunieda,S.; Larson,N.M.; Leal,L.; Lestone,J.P.; Little,R.C.; McCutchan,E.A.; MacFarlane,R.E.; MacInnes,M.; Mattoon,C.M.; McKnight,R.D.; Mughabghab,S.F.; Nobre,G.P.A.; Palmiotti,G.; Palumbo,A.; Pigni,M.T.; Pronyaev,V.G.; Sayer,R.O.; Sonzogni,A.A.; Summers,N.C.; Talou,P.; Thompson,I.J.; Trkov,A.; Vogt,R.L.; van der Marck,S.C.; Wallner,A.; White,M.C.; Wiarda,D.; Young,P.G.

    2011-12-01

    The ENDF/B-VII.1 library is our latest recommended evaluated nuclear data file for use in nuclear science and technology applications, and incorporates advances made in the five years since the release of ENDF/B-VII.0. These advances focus on neutron cross sections, covariances, fission product yields and decay data, and represent work by the US Cross Section Evaluation Working Group (CSEWG) in nuclear data evaluation that utilizes developments in nuclear theory, modeling, simulation, and experiment. The principal advances in the new library are: (1) An increase in the breadth of neutron reaction cross section coverage, extending from 393 nuclides to 423 nuclides; (2) Covariance uncertainty data for 190 of the most important nuclides, as documented in companion papers in this edition; (3) R-matrix analyses of neutron reactions on light nuclei, including isotopes of He, Li, and Be; (4) Resonance parameter analyses at lower energies and statistical high energy reactions for isotopes of Cl, K, Ti, V, Mn, Cr, Ni, Zr and W; (5) Modifications to thermal neutron reactions on fission products (isotopes of Mo, Tc, Rh, Ag, Cs, Nd, Sm, Eu) and neutron absorber materials (Cd, Gd); (6) Improved minor actinide evaluations for isotopes of U, Np, Pu, and Am (we are not making changes to the major actinides {sup 235,238}U and {sup 239}Pu at this point, except for delayed neutron data and covariances, and instead we intend to update them after a further period of research in experiment and theory), and our adoption of JENDL-4.0 evaluations for isotopes of Cm, Bk, Cf, Es, Fm, and some other minor actinides; (7) Fission energy release evaluations; (8) Fission product yield advances for fission-spectrum neutrons and 14 MeV neutrons incident on {sup 239}Pu; and (9) A new decay data sublibrary. Integral validation testing of the ENDF/B-VII.1 library is provided for a variety of quantities: For nuclear criticality, the VII.1 library maintains the generally-good performance seen for VII.0

  10. The CCONE Code System and its Application to Nuclear Data Evaluation for Fission and Other Reactions

    Science.gov (United States)

    Iwamoto, O.; Iwamoto, N.; Kunieda, S.; Minato, F.; Shibata, K.

    2016-01-01

    A computer code system, CCONE, was developed for nuclear data evaluation within the JENDL project. The CCONE code system integrates various nuclear reaction models needed to describe nucleon, light charged nuclei up to alpha-particle and photon induced reactions. The code is written in the C++ programming language using an object-oriented technology. At first, it was applied to neutron-induced reaction data on actinides, which were compiled into JENDL Actinide File 2008 and JENDL-4.0. It has been extensively used in various nuclear data evaluations for both actinide and non-actinide nuclei. The CCONE code has been upgraded to nuclear data evaluation at higher incident energies for neutron-, proton-, and photon-induced reactions. It was also used for estimating β-delayed neutron emission. This paper describes the CCONE code system indicating the concept and design of coding and inputs. Details of the formulation for modelings of the direct, pre-equilibrium and compound reactions are presented. Applications to the nuclear data evaluations such as neutron-induced reactions on actinides and medium-heavy nuclei, high-energy nucleon-induced reactions, photonuclear reaction and β-delayed neutron emission are mentioned.

  11. The CCONE Code System and its Application to Nuclear Data Evaluation for Fission and Other Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Iwamoto, O., E-mail: iwamoto.osamu@jaea.go.jp; Iwamoto, N.; Kunieda, S.; Minato, F.; Shibata, K.

    2016-01-15

    A computer code system, CCONE, was developed for nuclear data evaluation within the JENDL project. The CCONE code system integrates various nuclear reaction models needed to describe nucleon, light charged nuclei up to alpha-particle and photon induced reactions. The code is written in the C++ programming language using an object-oriented technology. At first, it was applied to neutron-induced reaction data on actinides, which were compiled into JENDL Actinide File 2008 and JENDL-4.0. It has been extensively used in various nuclear data evaluations for both actinide and non-actinide nuclei. The CCONE code has been upgraded to nuclear data evaluation at higher incident energies for neutron-, proton-, and photon-induced reactions. It was also used for estimating β-delayed neutron emission. This paper describes the CCONE code system indicating the concept and design of coding and inputs. Details of the formulation for modelings of the direct, pre-equilibrium and compound reactions are presented. Applications to the nuclear data evaluations such as neutron-induced reactions on actinides and medium-heavy nuclei, high-energy nucleon-induced reactions, photonuclear reaction and β-delayed neutron emission are mentioned.

  12. Fission time-scale in experiments and in multiple initiation model

    Energy Technology Data Exchange (ETDEWEB)

    Karamian, S. A., E-mail: karamian@nrmail.jinr.ru [Joint Institute for Nuclear Research (Russian Federation)

    2011-12-15

    Rate of fission for highly-excited nuclei is affected by the viscose character of the systemmotion in deformation coordinates as was reported for very heavy nuclei with Z{sub C} > 90. The long time-scale of fission can be described in a model of 'fission by diffusion' that includes an assumption of the overdamped diabatic motion. The fission-to-spallation ratio at intermediate proton energy could be influenced by the viscosity, as well. Within a novel approach of the present work, the cross examination of the fission probability, time-scales, and pre-fission neutron multiplicities is resulted in the consistent interpretation of a whole set of the observables. Earlier, different aspects could be reproduced in partial simulations without careful coordination.

  13. Photofissility of actinide nuclei at intermediate energies

    International Nuclear Information System (INIS)

    Deppman, A.; Tavares, O.A.P.; Duarte, S.B.; Oliveira, E.C. de; Arruda-Neto, J.D.T.; Pina, S.R. de; Likhachev, V.P.; Mesa, J.; Goncalves, M.

    2001-08-01

    We analyze the recent experimental data on photofissility for 237 Np, 238 U, and 232 Th at incident photon energies above 200 MeV. For this analysis, we developed a Monte carlo algorithm for the nuclear evaporation process in photonuclear reactions. This code is used in association with the multi-collisional model for the photon-induced intranuclear cascade process. Our results show a good quantitative and qualitative agreement with the experimental data. It is shown that the emission of protons and alpha particles at the evaporation stage is an important component for the non-saturation of the actinides photofissility up to, at least, 1GeV. (author)

  14. Project 'Installation of a stand at the horizontal channel of the MARIA Research Reactor, Otwock-Swierk, Poland, for the research of transmutation of minor actinides and fission products'

    International Nuclear Information System (INIS)

    Szuta, M.

    2006-01-01

    As a long range objective we would like to focus on management of the fuel economy in the sub-critical assembly of the accelerator driven system (ADS) in terms of long lived fission products (LLFP) and minor actinides (MA) transmutation. Transmutation of the radioactive waste (RW) is an important element within the technical objective of the optimal management of the fuel economy in the sub-critical assembly of the accelerator driven system (ADS). Analysis of possible ways of reduction of radioactive wastes by transmutation of radioactive long-lived fission products such as 99 Tc, 129 I and 135 Cs and by burning up of transuranic nuclides implies that the sub-critical assembly of the accelerator driven system should consist of three zones. The requirement of three zones comes out of the fact that each radioactive isotope to be reduced is to be located in a different spectrum of thermal, epithermal and high energy neutron fluxes. High flux thermal neutron environment (≥10 16 n/cm 3 ·s) is expected as the best way for the transmutation of most of the radioactive waste to stable or short-lived nuclides and for increasing the probability for fission such actinides as 237 Np and 238 Np. The concept of ADS system for energy production and for transmutation is quite new to some extent and from this reason it requires many theoretical and experimental studies. The research of transmutation is a very large area of study requiring a significant experimental and financial support, so it can be performed only within the international cooperation. Specifically, the proposed research within this CRP requires important means, in terms of high-energy proton beams, spallation targets, sub-critical assembly, measurement instrumentation, post-irradiation characterisation and its testing and, of course, manpower for the interpretation of results, modelling observed phenomena, and programme management. The personal involved in the research is to be a skilled personal of

  15. Safety and environmental aspects of partitioning and transmutation of actinides and fission products. Proceedings of a technical committee meeting held in Vienna, 29 November - 2 December 1993

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-01-01

    There is considerable interest in many countries in the partitioning and transmutation of long lived radionuclides as a potential complement to the closed fuel cycle. Recognizing this, the IAEA organized a Technical Committee Meeting on Safety and Environmental Aspects of Partitioning and Transmutation of Actinides and Fission Products, to review the current status of progress of national and international programmes and identify the most important directions of co-operation. The results of the Technical Committee meeting are presented in this document. Refs, figs and tabs.

  16. Safety and environmental aspects of partitioning and transmutation of actinides and fission products. Proceedings of a technical committee meeting held in Vienna, 29 November - 2 December 1993

    International Nuclear Information System (INIS)

    1995-01-01

    There is considerable interest in many countries in the partitioning and transmutation of long lived radionuclides as a potential complement to the closed fuel cycle. Recognizing this, the IAEA organized a Technical Committee Meeting on Safety and Environmental Aspects of Partitioning and Transmutation of Actinides and Fission Products, to review the current status of progress of national and international programmes and identify the most important directions of co-operation. The results of the Technical Committee meeting are presented in this document. Refs, figs and tabs

  17. Spectroscopical study of the yrast and yrare structure in far-from-stability nuclei; Etude spectroscopique de la structure yrast et yrare de noyaux loin de la stabilite

    Energy Technology Data Exchange (ETDEWEB)

    Hoellinger Fabien [Institut de Recherches Subatomiques, 23, Rue du Loess, BP 28, 67037 Strasbourg Cedex 2 (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)

    1999-01-13

    The nuclear structure study of neutron-rich nuclei was realized with the EUROGAM II array in two different experiments. The first study consisted in the analysis of the product of spontaneous fission of {sup 248}Cm. Three neutron-rich cerium isotopes {sup 147,149,151}Ce were analyzed. A level scheme for {sup 151}Ce is presented for the first time. The yrast structure of the three nuclei does not show alternative parity bands as expected in this region of octupole deformations. We studied the rotational structure of the bands and this leads to suggest Nilsson configurations to some of them. The aim of this second experiment was the study of the nuclei {sup 99}Mo, {sup 101}Tc, {sup 103}Ru. The three nuclei are situated on the neutron-rich side of the nuclear chart and are produced as fission fragments of a heavy-ion induced reaction. Some bands are extended to higher spins and some new bands are observed. The structure of the rotational bands is interpreted by means of the Hartree-Fock-Bogolyubov model. A last experiment intended to study the structure of the proton-rich nucleus {sup 223}Pa has been achieved with the JURO+RITU array located at Jyvaeskylae (Finland). In this proton-rich actinide region, the nuclei develop octupole features around Z{approx_equal}88, N{approx_equal}132. The analysis of this experiment leads to the first assignment of gamma transitions to the {sup 223}Pa. (author) 91 refs., 78 figs., 16 tabs.

  18. Nuclei in high forms

    International Nuclear Information System (INIS)

    Szymanski, Z.; Berger, J.F.; Heenen, P.H.; Heyde, K.; Haas, B.; Janssens, R.; Paya, D.; Gogny, D.; Huber, G.; Bjoernholm, S.; Brack, M.

    1991-01-01

    The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters

  19. Influence of angular momentum on fission fragment mass distribution: Interpretation within Langevin dynamics

    International Nuclear Information System (INIS)

    Ryabov, E.G.; Karpov, A.V.; Adeev, G.D.

    2006-01-01

    Dependence of fission fragments mass distribution on the angular momentum within Langevin dynamics is studied. The calculations are performed in the framework of the rotating temperature-dependent finite-range liquid drop model. The calculations are done for the five nuclei, representing heavy fissioning nuclei, medium fissioning nuclei and light fissioning one with the angular momentum varied in the wide range from l=0 to l=70-bar . The dependence coefficients dσ M 2 /dl 2 for the investigated nuclei are extracted. The comparison of the extracted values with the experimental data reveals a good agreement for all the cases (the heavy, medium, and light fissioning nuclei). It is found out that the obtained dependence of σ M 2 on l can be explained with the help of temperature at scission as a function of l. The latter dependence is determined by dependence of the mean prescission neutron multiplicity on l. The analysis of this dependence is done as a competition between fission process and neutron evaporation. 'Remembering of the former large fluctuations of mass asymmetry coordinate during descent from the saddle to scission' is considered. It is shown that the 'remembering effect' takes place, but does not play a crucial role for the investigated dependence of σ M 2 on l

  20. Investigation of the heavy nuclei fission with anomalously high values of the fission fragments total kinetic energy

    Science.gov (United States)

    Khryachkov, Vitaly; Goverdovskii, Andrei; Ketlerov, Vladimir; Mitrofanov, Vecheslav; Sergachev, Alexei

    2018-03-01

    Binary fission of 232Th and 238U induced by fast neutrons were under intent investigation in the IPPE during recent years. These measurements were performed with a twin ionization chamber with Frisch grids. Signals from the detector were digitized for further processing with a specially developed software. It results in information of kinetic energies, masses, directions and Bragg curves of registered fission fragments. Total statistics of a few million fission events were collected during each experiment. It was discovered that for several combinations of fission fragment masses their total kinetic energy was very close to total free energy of the fissioning system. The probability of such fission events for the fast neutron induced fission was found to be much higher than for spontaneous fission of 252Cf and thermal neutron induced fission of 235U. For experiments with 238U target the energy of incident neutrons were 5 MeV and 6.5 MeV. Close analysis of dependence of fission fragment distribution on compound nucleus excitation energy gave us some explanation of the phenomenon. It could be a process in highly excited compound nucleus which leads the fissioning system from the scission point into the fusion valley with high probability.

  1. Intermediate energy nuclear fission

    International Nuclear Information System (INIS)

    Hylten, G.

    1982-01-01

    Nuclear fission has been investigated with the double-kinetic-energy method using silicon surface barrier detectors. Fragment energy correlation measurements have been made for U, Th and Bi with bremsstrahlung of 600 MeV maximum energy. Distributions of kinetic energy as a function of fragment mass are presented. The results are compared with earlier photofission data and in the case of bismuth, with calculations based on the liquid drop model. The binary fission process in U, Yb, Tb, Ce, La, Sb, Ag and Y induced by 600 MeV protons has been investigated yielding fission cross sections, fragment kinetic energies, angular correlations and mass distributions. Fission-spallation competition calculations are used to deduce values of macroscopic fission barrier heights and nuclear level density parameter values at deformations corresponding to the saddle point shapes. We find macroscopic fission barriers lower than those predicted by macroscopic theories. No indication is found of the Businaro Gallone limit expected to occur somewhere in the mass range A = 100 to A = 140. For Ce and La asymmetric mass distributions similar to those in the actinide region are found. A method is described for the analysis of angular correlations between complementary fission products. The description is mainly concerned with fission induced by medium-energy protons but is applicable also to other projectiles and energies. It is shown that the momentum and excitation energy distributions of cascade residuals leading to fission can be extracted. (Author)

  2. Analysis of incident-energy dependence of delayed neutron yields in actinides

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, Mohamad Nasrun bin Mohd, E-mail: monasr211@gmail.com; Metorima, Kouhei, E-mail: kohei.m2420@hotmail.co.jp; Ohsawa, Takaaki, E-mail: ohsawa@mvg.biglobe.ne.jp; Hashimoto, Kengo, E-mail: kengoh@pp.iij4u.or.jp [Graduate School of Science and Engineering, Kindai University, Kowakae, Higashi-Osaka, 577-8502 (Japan)

    2015-04-29

    The changes of delayed neutron yields (ν{sub d}) of Actinides have been analyzed for incident energy up to 20MeV using realized data of precursor after prompt neutron emission, from semi-empirical model, and delayed neutron emission probability data (P{sub n}) to carry out a summation method. The evaluated nuclear data of the delayed neutron yields of actinide nuclides are still uncertain at the present and the cause of the energy dependence has not been fully understood. In this study, the fission yields of precursor were calculated considering the change of the fission fragment mass yield based on the superposition of fives Gaussian distribution; and the change of the prompt neutrons number associated with the incident energy dependence. Thus, the incident energy dependent behavior of delayed neutron was analyzed.The total number of delayed neutron is expressed as ν{sub d}=∑Y{sub i} • P{sub ni} in the summation method, where Y{sub i} is the mass yields of precursor i and P{sub ni} is the delayed neutron emission probability of precursor i. The value of Y{sub i} is derived from calculation of post neutron emission mass distribution using 5 Gaussian equations with the consideration of large distribution of the fission fragments. The prompt neutron emission ν{sub p} increases at higher incident-energy but there are two different models; one model says that the fission fragment mass dependence that prompt neutron emission increases uniformly regardless of the fission fragments mass; and the other says that the major increases occur at heavy fission fragments area. In this study, the changes of delayed neutron yields by the two models have been investigated.

  3. Recycling of actinides and nuclear waste products. Annual report of the research programme 1997

    International Nuclear Information System (INIS)

    Konings, R.J.M.; Bakker, K.; Boerrigter, H.; Damen, P.G.M.; Gruppelaar, H.; Huntelaar, M.E.; Kloosterman, J.L.

    1998-07-01

    The research program on the title subject started in 1994 and is planned to be completed in 1998. In this period several technical and scientific aspects of recycling and transmutation are investigated in different projects. The results of the 1997 projects, carried out in the period July 1997 to June 1998, are summarized and described in this report. The 1997 projects concern (1) transmutation of actinides in inert matrices with the aim to design, test and characterize uranium-free fission materials for the transmutation of actinides, both for single as for multiple recycling strategies; (2) scenario studies for plutonium recycling with the aim to gain insight into the possibilities to reduce plutonium reserves by using plutonium as a fissionable material in reactors; (3) transmutation by means of accelerator-driven systems with the aim to analyze the options for the burning of plutonium in accelerator-driven, thorium-based systems; and (4) separation of actinides and lanthanides by means of Supported Liquid Membranes with the aim to study the possibility to extract americium from nuclear waste materials. refs

  4. Experimental study of energy dependence of proton induced fission cross sections for heavy nuclei in the energy range 200-1000 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Kotov, A.A.; Gavrikov, Yu.A.; Vaishnene, L.A.; Vovchenko, V.G.; Poliakov, V.V.; Fedorov, O.Ya.; Chestnov, Yu.A.; Shchetkovskiy, A.I [Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, Orlova roscha 1, 188300 (Russian Federation); Fukahori, T. [Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan)

    2005-07-01

    The results of the total fission cross sections measurements for {sup nat}Pb, {sup 209}Bi, {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu nuclei at the energy proton range 200-1000 MeV are presented. Experiments were carried out at 1 GeV synchrocyclotron of Petersburg Nuclear Physics Institute (Gatchina). The measurement method is based on the registration in coincidence of both complementary fission fragments by two gas parallel plate avalanche counters, located at a short distance and opposite sides of investigated target. The insensitivity of parallel plate avalanche counters to neutron and light charged particles allowed us to place the counters together with target immediately in the proton beam providing a large solid angle acceptance for fission fragment registration and reliable identification of fission events. The proton flux on the target to be studied was determined by direct counting of protons by scintillation telescope. The measured energy dependence of the total fission cross sections is presented. Obtained results are compared with other experimental data as well as with calculation in the frame of the cascade evaporation model. (authors)

  5. The TENDL neutron data library and the TEND1038 38-group neutron constant system

    International Nuclear Information System (INIS)

    Abramovich, S.N.; Gorelov, V.P.; Gorshikhin, A.A.; Grebennikov, A.N.; Il'in, V.N.; Krut'ko, N.A.; Farafontov, G.G.

    2002-01-01

    The library contains neutron data for 103 nuclei - i.e. for 38 actinide nuclei (from 232 Th to 249 Cm), 26 fission fragment nuclei and 39 nuclei in structural and technological materials. The 38-group constants were obtained from TENDL. The high-energy group boundary is 20 MeV. The energy range below 1.2 eV contains 11 groups. Temperature and resonance effects were taken into account. The delayed neutron parameters for 6 groups and the yields of 40 fission fragments were obtained (light and heavy, stable and non-stable). The fast neutron features of spherical critical assemblies were calculated using constants from TEND1038. (author)

  6. Proceedings of the specialists' meeting on physics and engineering of fission and spallation, 1989

    International Nuclear Information System (INIS)

    Nakagome, Yoshihiro

    1990-07-01

    The third meeting was held on August 1, and the fourth meeting was held on December 12, 1989. The reports of the international conferences on 50 years research on nuclear fission in Germany and USA, and the reports on the nuclear data of fission-produced nuclei for evaluating reactor decay heat, the atomic mass formula considering proton-neutron interaction and unstable nuclei, research on short life fission fragments by on-line isotope separation process, the reactor physics on waste annihilation disposal and fuel breeding with an accelerator, the double differential cross section of back neutrons in nuclear spallation reaction, measurement of fission cross section and fission neutron spectra with fast neutrons, U-235 fission spectra by unfolding activation foil data and production mechanisms of intermediate mass fragments from hot nuclei-emission of complex and fission fragments for 84 Kr+ 27 Al at 10.6 MeV/u were made. (K.I.)

  7. Study of five-dimensional potential-energy surfaces for actinide isotopes by the macroscopic-microscopic method

    Science.gov (United States)

    Fan, T. S.; Wang, Z. M.; Zhu, X.; Zhu, W. J.; Zhong, C. L.

    2017-09-01

    In this work, the nuclear potential-energy of the deformed nuclei as a function of shape coordinates is calculated in a five-dimensional (5D) parameter space of the axially symmetric generalized Lawrence shapes, on the basis of the macroscopic-microscopic method. The liquid-drop part of the nuclear energy is calculated according to the Myers-Swiatecki model and the Lublin-Strasbourg-drop (LSD) formula. The Woods-Saxon and the folded-Yukawa potentials for deformed nuclei are used for the shell and pairing corrections of the Strutinsky-type. The pairing corrections are calculated at zero temperature, T, related to the excitation energy. The eigenvalues of Hamiltonians for protons and neutrons are found by expanding the eigen-functions in terms of harmonic-oscillator wave functions of a spheroid. Then the BCS pair is applied on the smeared-out single-particle spectrum. By comparing the results obtained by different models, the most favorable combination of the macroscopic-microscopic model is known as the LSD formula with the folded-Yukawa potential. Potential-energy landscapes for actinide isotopes are investigated based on a grid of more than 4,000,000 deformation points and the heights of static fission barriers are obtained in terms of a double-humped structure on the full 5D parameter space. In order to locate the ground state shapes, saddle points, scission points and optimal fission path on the calculated 5D potential-energy surface, the falling rain algorithm and immersion method are designed and implemented. The comparison of our results with available experimental data and others' theoretical results confirms the reliability of our calculations.

  8. Fission of Al, Ti, Co, Zr, Nb, Ag, In, Nd, Sm, and Ta nuclei induced by 0.8-1.8 GeV photons

    International Nuclear Information System (INIS)

    Lima, D.A. de; Martins, J.B.; Tavares, O.A.P.

    1989-01-01

    Samples of Al, Ti, Co, Zr, Nb, Ag, In, Nd, Sm, and Ta elements in contact with solid state nuclear track detectors were exposed to 0.8-1.8 GeV bremsstrahlung beams at the 2.5-GeV Electron Synchrotron of the Bonn University. The detectors were processed to produce visible fission tracks for track analysis with optical microscopes. Absolute mean cross section per photon and fissility were evaluated. Results are discussed and compared with other photofission data as well as with estimates from the current fission models. A broad minimum found for nuclear fissility of 10 -4 -10 -3 covering the range 15 approx Z 2 /A approx 25 seems to confirm the predictions from the models. For Al and Ti nuclei the probability of fission amounts to approx 10 -1 . (author) [pt

  9. Evaluation of fission product worth margins in PWR spent nuclear fuel burnup credit calculations

    International Nuclear Information System (INIS)

    Blomquist, R.N.; Finck, P.J.; Jammes, C.; Stenberg, C.G.

    1999-01-01

    Current criticality safety calculations for the transportation of irradiated LWR fuel make the very conservative assumption that the fuel is fresh. This results in a very substantial overprediction of the actual k eff of the transportation casks; in certain cases, this decreases the amount of spent fuel which can be loaded in a cask, and increases the cost of transporting the spent fuel to the repository. Accounting for the change of reactivity due to fuel depletion is usually referred to as ''burnup credit.'' The US DOE is currently funding a program aimed at establishing an actinide only burnup credit methodology (in this case, the calculated reactivity takes into account the buildup or depletion of a limited number of actinides). This work is undergoing NRC review. While this methodology is being validated on a significant experimental basis, it implicitly relies on additional margins: in particular, the absorption of neutrons by certain actinides and by all fission products is not taken into account. This provides an important additional margin and helps guarantee that the methodology is conservative provided these neglected absorption are known with reasonable accuracy. This report establishes the accuracy of fission product absorption rate calculations: (1) the analysis of European fission product worth experiments demonstrates that fission product cross-sections available in the US provide very good predictions of fission product worth; (2) this is confirmed by a direct comparison of European and US cross section evaluations; (3) accuracy of Spent Nuclear Fuel (SNF) fission product content predictions is established in a recent ORNL report where several SNF isotopic assays are analyzed; and (4) these data are then combined to establish in a conservative manner the fraction of the predicted total fission product absorption which can be guaranteed based on available experimental data

  10. Approximate energy correction for particle number summetry breaking in constrained Hartree-Fock plus BCS calculations

    International Nuclear Information System (INIS)

    Redon, N.; Meyer, J.; Meyer, M.

    1989-01-01

    An approximate restoration of the particle number symmetry, a la Lipkin-Nogami, is numerically investigated in the context of Constrained Hartree-Fock plus BCS calculations. Its effect is assessed in a variety of physical situations like potential energy landscapes in transitional nuclei, shape isomerism at low spin and fission barriers of actinide nuclei

  11. Isospin Conservation in Neutron Rich Systems of Heavy Nuclei

    Science.gov (United States)

    Jain, Ashok Kumar; Garg, Swati

    2018-05-01

    It is generally believed that isospin would diminish in its importance as we go towards heavy mass region due to isospin mixing caused by the growing Coulomb forces. However, it was realized quite early that isospin could become an important and useful quantum number for all nuclei including heavy nuclei due to neutron richness of the systems [1]. Lane and Soper [2] also showed in a theoretical calculation that isospin indeed remains quite good in heavy mass neutron rich systems. In this paper, we present isospin based calculations [3, 4] for the fission fragment distributions obtained from heavy-ion fusion fission reactions. We discuss in detail the procedure adopted to assign the isospin values and the role of neutron multiplicity data in obtaining the total fission fragment distributions. We show that the observed fragment distributions can be reproduced rather reasonably well by the calculations based on the idea of conservation of isospin. This is a direct experimental evidence of the validity of isospin in heavy nuclei, which arises largely due to the neutron-rich nature of heavy nuclei and their fragments. This result may eventually become useful for the theories of nuclear fission and also in other practical applications.

  12. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    The fission decay of highly neutron-rich uranium isotopes is investigated which shows interesting new features in the barrier properties and neutron emission characteristics in the fission process. 233U and 235U are the nuclei in the actinide region in the beta stability valley which are thermally fissile and have been mainly ...

  13. Estimation of penetration depth of fission products in cladding Hull

    International Nuclear Information System (INIS)

    Kim, Hee Moon; Jung, Yang Hong; Yoo, Byong Ok; Choo, Yong Sun; Hong, Kwon Pyo

    2005-01-01

    A disposal and a reprocessing for spent fuel rod with high burnup need de-cladding procedure. Pellet in this rod has been separated from a cladding hull to reduce a radioactivity of hull by chemical and mechanical methods. But fission products and actinides(U,Pu) still remain inside of cladding hull by chemical bonding and fission spike, which is called as 'contamination'. More specific removal of this contamination would have been considered. In this study, the sorts of fission products and penetration depth in hull were observed by EPMA test. To analyze this behavior, SRIM 2000 code was also used as energies of fission products and an oxide thickness of hull

  14. Present status of JENDL-4

    International Nuclear Information System (INIS)

    Shibata, Keiichi

    2009-01-01

    The fourth version of Japanese Evaluated Nuclear Data Library is being developed at the JAEA Nuclear Data Center in cooperation with the Japanese Nuclear Data Committee. As for actinides, we already released JENDL Actinoid File 2008, which contains the evaluated data for 79 nuclei. The high-energy cross sections of FP nuclei have been evaluated by using the CCONE and POD statistical model codes. The nuclear data for structural materials and light nuclei are being revised. The fission product yields were updated on the basis of ENDF/B-VII.0. Ternary fission was included in the yield data. (author)

  15. The spectroscopy of fission fragments

    International Nuclear Information System (INIS)

    Phillips, W.R.

    1998-01-01

    High-resolution measurements on γ rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author)

  16. Observation of large scissors resonance strength in actinides.

    Science.gov (United States)

    Guttormsen, M; Bernstein, L A; Bürger, A; Görgen, A; Gunsing, F; Hagen, T W; Larsen, A C; Renstrøm, T; Siem, S; Wiedeking, M; Wilson, J N

    2012-10-19

    The orbital M1 scissors resonance has been measured for the first time in the quasicontinuum of actinides. Particle-γ coincidences are recorded with deuteron and (3)He-induced reactions on (232)Th. The residual nuclei (231,232,233)Th and (232,233) Pa show an unexpectedly strong integrated strength of B(M1)=11-15μ(n)(2) in the E(γ)=1.0-3.5 MeV region. The increased γ-decay probability in actinides due to scissors resonance is important for cross-section calculations for future fuel cycles of fast nuclear reactors and may also have an impact on stellar nucleosynthesis.

  17. Fission of highly excited nuclei investigated in complete kinematic measurements

    International Nuclear Information System (INIS)

    Rodriguez-Sanchez, J. L.; Benlliure, J.; Taieb, J.; Avarez-Pol, H.; Audouin, L.; Ayyad, Y.; Belier, G.; Boutoux, G.; Casarejos, E.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelic-Heil, A.; Kurz, N.; Laurent, B.; Martin, J. F.; Paradela, C.; Pellereau, E.; Pietras, B.; Prochazka, A.; Ramos, D.; Rodriguez-Tajes, C.; Rossi, D.; Simon, H.; Tassan-Got, L.; Vargas, J.; Voss, B.

    2013-01-01

    Fission is an extremely complex mechanism that requires a dynamical approach to describe the evolution of the process in terms of intrinsic and collective excitations of the nuclear constituents. In order to determine these effects a complex experimental setup was mounted at GSI, which allowed us for the first time the full identification in charge and mass of all fission fragments thanks to a magnetic separation and the use of the inverse kinematic technique. Moreover, we also measured the neutron multiplicities and the light-charged particles emitted in coincidence with fission. These complete kinematic measurements will be used to define sensitive observables to dissipative and transient effects in fission. In this manuscript we present the first results for the total fission cross sections. (authors)

  18. Fission product yield data for the transmutation of minor actinide nuclear waste

    International Nuclear Information System (INIS)

    2008-04-01

    A report issued by an international study group for the transmutation of nuclear waste using accelerator driven systems has highlighted the need for specific sets of nuclear data. These authoritative requirements include fission product yields at an intermediate incident neutron energy of up to 150 MeV. Before the start of the present CRP on fission product yield data for the transmutation of nuclear waste, only four types of evaluated fission yield data sets existed, namely for spontaneous fission, and for fission induced by thermal, fast (or fission) spectrum, and by 'high energy' (14-15 MeV) neutrons. A new type of evaluation for energy dependent neutron induced fission yields was required for this project. In view of the scarcity of experimental data, such an evaluation has to be based on systematics and theoretical model calculations. Unlike fission cross-sections, where nuclear models are being used successfully for the calculation of unmeasured cross-section ranges, such models or theories existed only for low energy fission yields. Hence the CRP participants entered a completely new field of research for which the progress and outcome were unpredictable. Clearly the ultimate goal of such an effort, namely an evaluation of energy dependent fission yields, could not be realized within the perceived lifetime of a CRP. The main emphasis of the CRP was on the development of adequate systematics and models for the calculation of energy dependent fission yields up to 150 MeV incident neutron energy. Several problems had to be solved, such as the correct choice of model parameters and multiplicity distributions of emitted neutrons, and the effect of multi-chance fission. Models and systematics have been tested for lower energy yields, but they failed to reproduce recent experimental data, particularly at higher energies, and the parameters had to be modified. Other models have been developed from the analysis of experimental data in order to derive systematic

  19. Survivability and Fusibility in Reactions Leading to Heavy Nuclei in the Vicinity of the N=126 Closed Shell

    International Nuclear Information System (INIS)

    Sagaidak, R. N.

    2009-01-01

    Nuclear fission is well suited to study the dynamic properties and dissipative processes in cold and moderately excited nuclei. It is also a unique tool to explore level density and shell effects at an extreme deformation. Despite the significant progress in the fission studies, the isospin dependence of fission properties and, in particular, of fission barrier heights still remains an open problem. Theoretical fission model parameters are tuned by using the experimental nuclear and fission data close to stability [1]. The models provide a reasonable description of the fission barriers close to the stability line. However, large deviations are observed between predictions of different models for the fission barriers of very neutron-deficient and neutron-rich nuclei. These discrepancies (by as much as 20-30 MeV, see, e.g. [2]) become especially important in the r-process calculations for extremely neutron-rich nuclei, whose fission barriers determine the termination of the r-process by fission [3]. Unfortunately, such neutron-rich nuclei will probably not become accessible in the nearest experiments. Therefore, fission properties of exotic nuclei and especially their isospin dependence can be investigated in alternative regions of the Nuclide Chart, which are accessible for such studies now. Fusion-evaporation cross sections for heavy fissile nuclei obtained in heavy ion induced reactions as well as their fission cross sections are mainly determined by statistical properties of decaying compound nuclei (CN) and first of all by the fission-barrier heights of nuclei involved in the de-excitation chains leading to observable evaporation residues (ER). At the same time, the ER production and fission in nearly symmetric projectile-target fusion reactions leading to the most neutron-deficient CN could be strongly suppressed due to the quasi-fission (QF) effect [4], as observed recently in the 4 8C a induced reactions leading to Ra [5] and Pb [6] CN. The production of

  20. The spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.R. [Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    High-resolution measurements on {gamma} rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author) 24 refs., 8 figs., 1 tab.

  1. Nuclear structure in cold rearrangement processes in fission and fusion

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, P.

    1998-11-01

    In fission and fusion of heavy nuclei large numbers of nucleons are rearranged at a scale of excitation energy very small compared to the binding energy of the nuclei. The energies involved are less than 40 MeV at nuclear temperatures below 1.5 MeV. The shapes of the configurations in the rearrangement of a binary system into a monosystem in fusion, or vice versa in fission, change their elongations by as much as 8 fm, the radius of the monosystem. The dynamics of the reactions macroscopically described by a potential energy surface, inertia parameters, dissipation, and a collision energy is strongly modified by the nuclear structure of the participating nuclei. Experiments showing nuclear structure effects in fusion and fission of the heaviest nuclei are reviewed. The reaction kinematics and the multitude of isotopes involved are investigated by detector techniques and by recoil spectrometers. The advancement of the latter allows to find very small reaction branches in the range of 10{sup -5} to 10{sup -10}. The experiments reveal nuclear structure effects in all stages of the rearrangement processes. These are discussed pointing to analogies in fusion and fission on the microscopic scale, notwithstanding that both processes macroscopically are irreversible. Heavy clusters, as 132Sn, 208Pb, nuclei with closed shell configurations N=82,126, Z=50,82 survive in large parts of the nuclear rearrangement. They determine the asymmetry in the mass distribution of low energy fission, and they allow to synthesise superheavy elements, until now up to element 112. Experiments on the cold rearrangement in fission and fusion are presented. Here, in the range of excitation energies below 12 MeV the phenomena are observed most convincingly. (orig.)

  2. Actinide behavior in the integral fast reactor

    International Nuclear Information System (INIS)

    Courtney, J.C.

    1993-05-01

    Goal of this project is to determine the consumption of Np-237, Pu-240, Am-241, and Am-243 in the Integral Fast Reactor (IFR) fuel cycle. These four actinides set the long term waste management criteria for spent nuclear fuel; if it can be demonstrated that they can be efficiently consumed in the IFR, then requirements for nuclear waste repositories can be much less demanding. Irradiations in the Experimental Breeder Reactor II (EBR-II) at Argonne National Laboratory's site near Idaho Falls, Idaho, will be conducted to determine fission and transmutation rates for the four nuclides. The experimental effort involves target package design, fabrication, quality assurance, and irradiation. Post irradiation analyses are required to determine the fission rates and neutron spectra in the EBR-II core

  3. Microscopical descriptions of the fission fragmentation developed at CEA Bruyeres (France)

    International Nuclear Information System (INIS)

    Sida, J. L.

    2007-01-01

    The fission process has been studied from 1939 but there is no full theoretical description of the process. Two approaches have been developped at CEA Bruyeres le Chatel (France) in the basis of microscopic calculations with the Gogny Force. The first one is based on mean field calculations of the fission parameters (Potential enegy landscape, inertial parameters). The evolution of the wave function of the system is followed from the saddle point to the scission line in an adiabatic dynamical approach in order to determine the fission fragment distributions [GOU04]. The second one used the theoretical nuclear database AMEDEE (http://www-phynu.cea.fr/science_en_ligne/carte_potentiels_microscopiques/carte_potentiel_nucleaire.htm) which includes the mean field potential of more than 7000 nuclei. A precise energy balance is done at the scission point in order to define the available energy for each possible fragmentation. A statistical model is than used to determine the fragments distributions [HEI06]. This work is an improvement of the statistical scission point model of Wilkins et al [WIL76]. The free parameters of the previous description have been reduced to the minimum and there is still one parameter value that define the scission configuration which is not used ass a free parameter but has been fixed for the systematic that will be presented. This two microscopical models will be presented and the results will be discussed and compared to experiments. We will also point on their possible use to realize data evaluation for the burn-up of minor actinides, wastes of nuclear plants. (Author)

  4. An optical potential for the statically deformed actinide nuclei derived from a global spherical potential

    Science.gov (United States)

    Al-Rawashdeh, S. M.; Jaghoub, M. I.

    2018-04-01

    In this work we test the hypothesis that a properly deformed spherical optical potential, used within a channel-coupling scheme, provides a good description for the scattering data corresponding to neutron induced reactions on the heavy, statically deformed actinides and other lighter deformed nuclei. To accomplish our goal, we have deformed the Koning-Delaroche spherical global potential and then used it in a channel-coupling scheme. The ground-state is coupled to a sufficient number of inelastic rotational channels belonging to the ground-state band to ensure convergence. The predicted total cross sections, elastic and inelastic angular distributions are in good agreement with the experimental data. As a further test, we compare our results to those obtained by a global channel-coupled optical model whose parameters were obtained by fitting elastic and inelastic angular distributions in addition to total cross sections. Our results compare quite well with those obtained by the fitted, channel-coupled optical model. Below neutron incident energies of about 1MeV, our results show that scattering into the rotational excited states of the ground-state band plays a significant role in the scattering process and must be explicitly accounted for using a channel-coupling scheme.

  5. Systematical calculations on the ground state properties of heavy and superheavy nuclei

    International Nuclear Information System (INIS)

    Ren, Z.Z.; Center of Theoretical Nuclear Physics, Lanzhou; Mao, Y.C.; Zhi, Q.J.; Xu, C.; Dong, T.K.

    2007-01-01

    The synthesis of superheavy elements is now a hot topic in nuclear physics. Alpha-decay and spontaneous fission are two main decay modes in heavy and superheavy regions. Theoretical studies on alpha radioactivity and spontaneous fission can provide useful information for experiments. We investigate the alpha-decay and spontaneous fission of heavy and superheavy nuclei with different models. This includes the alpha-decay energies, alpha decay half-lives, and half-lives of spontaneous fission. The theoretical alpha-decay half-lives are in good agreement with experimental ones. The calculated half-lives of spontaneous fission are in reasonable agreement with present data. The properties of unknown nuclei are predicted. (author)

  6. Rapid ion-exchange separations of actinides

    International Nuclear Information System (INIS)

    Usuda, Shigekazu

    1988-01-01

    For the purpose of studying short-lived actinide nuclides, three methods for rapid ion exchange separation of actinide elements with mineral acid-alcohol mixed media were developed: anion exchange with nitric acid-methyl alcohol mixed media to separate the transplutonium and rare earth elements from target material, U or Pu and Al catcher foils; anion exchange with hydrochloric acid-methyl alcohol media to separate Am+Cm, Bk and Cf+Fm from the target, catcher foils and major fission products; and cation exchange with hydrochloric acid-methyl alcohol media and with concentrated hydrochloric acid to separate the transplutonium elements as a group from the rare earths after eliminating the large amounts of U, Al, Cu, Fe etc. The methods enable one to perform rapid and effective separation at elevated temperature (90 deg C) and immediate source preparation for alpha-ray spectrometry. (author) 47 refs.; 10 figs

  7. Measurement of Am-242 fission yields at the Lohengrin spectrometer; improvement and Benchmarking of the semi-empirical code GEF

    International Nuclear Information System (INIS)

    Amouroux, Charlotte

    2014-01-01

    The study of fission yields has a major impact on the characterization and understanding of the fission process and is mandatory for reactor applications. While the yields are known for the major actinides (U-235, Pu-239) in the thermal neutron-induced fission, only few measurements were performed on Am-242. Moreover, the two main data libraries do not agree among each other on the light peak. Am-241 and Am-242 are nuclei of interest for the MOX-fuel reactors and for the reduction of nuclear waste radiotoxicity using transmutation reactions. Thus, a campaign of precise measurement of the fission mass yields from the reaction Am-241(2n,f) was performed at the Lohengrin mass spectrometer (ILL, France) for both the light and the heavy peak. Forty-one masses were measured. Moreover, the measurement of the isotopic fission yields on the heavy peak by gamma-ray spectrometry led to the extraction of 20 independent isotopic yields. Our measurement was also meant to determine whether there is a difference in fission yields between the Am-242 isomeric state and its ground state as it exists in fission cross sections. The experimental method used to answer this question is based on the measurement a set of fission mass yields as a function of the ratio of Am-242gs to Am-242m fission rate. Results show that the mass yields are independent of the fission rate ratio. A future experimental campaign is proposed to observe a possible influence on the isomeric yields. The theoretical models are nowadays unable to predict the fission yields with enough accuracy and therefore we have to rely on experimental data and phenomenological models. The accuracy of the predictions of the semi empirical GEF fission model predictions makes it a useful tool for evaluation. This thesis also presents the physical content and part of the development of this model. Validation of the kinetic energy distributions, isomeric yields and fission yields predictions was performed. The extension of the GEF

  8. Recent advances in heavy-ion-induced fission

    International Nuclear Information System (INIS)

    Plasil, F.

    1984-01-01

    Three topics are discussed. The first deals with results that have been published recently on angular-momentum-dependent fission barriers. They are discussed because of the significance that we attach to them. We feel that, after a decade of study and controversy, we have arrived at a quantitative understanding of the competition between heavy-ion-induced fission and particle emission from compound nuclei at relatively low bombarding energies. The second topic concerns the extension of our heavy-ion-induced fission studies to higher energies. It is clear that in this regime the effects, both of fission following incomplete fusion and of extra-push requirements, need to be considered. Finally, discussed are our recent conclusions concerning the fissionlike decay of products from reactions between two 58 Ni nuclei at an incident energy, E/A, of 15.3 MeV, as well as the impact of our findings on the conclusions drawn from previous, similar measurements. 39 references

  9. Prompt muon-induced fission: A probe for nuclear friction in large-amplitude collective motion

    International Nuclear Information System (INIS)

    Oberacker, V.E.; Umar, A.S.; Wells, J.C.; Strayer, M.R.; Maruhn, J.A.; Reinhard, P.G.

    1998-01-01

    Excited muonic atoms in the actinide region may induce prompt fission by inverse internal conversion, i.e. the excitation energy of the muonic atom is transferred to the nucleus. The authors solve the time dependent Dirac equation for the muonic spinor wave function in the Coulomb field of the fissioning nucleus on a 3-dimensional lattice and demonstrate that the muon attachment probability to the light fission fragment is a measure of the nuclear energy dissipation between the outer fission barrier and the scission point

  10. Comparison calculations for an accelerator-driven minor actinide burner

    International Nuclear Information System (INIS)

    2002-01-01

    International interest in accelerator-driven systems (ADS) has recently been increasing in view of the important role that these systems may play as efficient minor actinide and long-lived fission-product (LLFP) burners and/or energy producers with an enhanced safety potential. However, the current methods of analysis and nuclear data for minor actinide and LLFP burners are not as well established as those for conventionally fuelled reactor systems. Hence, in 1999, the OECD/NEA Nuclear Science Committee organised a benchmark exercise for an accelerator-driven minor actinide burner to check the performances of reactor codes and nuclear data for ADS with unconventional fuel and coolant. The benchmark model was a lead-bismuth-cooled subcritical system driven by a beam of 1 GeV protons. This report provides an analysis of the results supplied by seven participants from eight countries. The analysis reveals significant differences in important neutronic parameters, indicating a need for further investigation of the nuclear data, especially minor actinide data, as well as the calculation methods. This report will be of particular interest to reactor physicists and nuclear data evaluators developing nuclear systems for nuclear waste management. (authors)

  11. Fission product inventory calculation by a CASMO/ORIGEN coupling program

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Heon; Kim, Jong Kyung [Hanyang University, Seoul (Korea, Republic of); Choi, Hang Bok; Roh, Gyu Hong; Jung, In Ha [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A CASMO/ORIGEN coupling utility program was developed to predict the composition of all the fission products in spent PWR fuels. The coupling program reads the CASMO output file, modifies the ORIGEN cross section library and reconstructs the ORIGEN input file at each depletion step. In ORIGEN, the burnup equation is solved for actinides and fission products based on the fission reaction rates and depletion flux of CASMO. A sample calculation has been performed using a 14 x 14 PWR fuel assembly and the results are given in this paper. 3 refs., 1 fig., 1 tab. (Author)

  12. Fission product inventory calculation by a CASMO/ORIGEN coupling program

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Heon; Kim, Jong Kyung [Hanyang University, Seoul (Korea, Republic of); Choi, Hang Bok; Roh, Gyu Hong; Jung, In Ha [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    A CASMO/ORIGEN coupling utility program was developed to predict the composition of all the fission products in spent PWR fuels. The coupling program reads the CASMO output file, modifies the ORIGEN cross section library and reconstructs the ORIGEN input file at each depletion step. In ORIGEN, the burnup equation is solved for actinides and fission products based on the fission reaction rates and depletion flux of CASMO. A sample calculation has been performed using a 14 x 14 PWR fuel assembly and the results are given in this paper. 3 refs., 1 fig., 1 tab. (Author)

  13. I. Fission Probabilities, Fission Barriers, and Shell Effects. II. Particle Structure Functions

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Kexing [Univ. of California, Berkeley, CA (United States)

    1999-05-01

    In Part I, fission excitation functions of osmium isotopes 185,186, 187, 189 Os produced in 3He +182,183, 184, 186W reactions, and of polonium isotopes 209,210, 211, 212Po produced in 3He/4He + 206, 207, 208Pb reactions, were measured with high precision. These excitation functions have been analyzed in detail based upon the transition state formalism. The fission barriers, and shell effects for the corresponding nuclei are extracted from the detailed analyses. A novel approach has been developed to determine upper limits of the transient time of the fission process. The upper limits are constrained by the fission probabilities of neighboring isotopes. The upper limits for the transient time set with this new method are 15x 10–21 sec and 25x 10–21 sec for 0s and Po compound nuclei, respectively. In Part II, we report on a search for evidence of the optical modulations in the energy spectra of alpha particles emitted from hot compound nuclei. The optical modulations are expected to arise from the ~-particle interaction with the rest of the nucleus as the particle prepares to exit. Some evidence for the modulations has been observed in the alpha spectra measured in the 3He-induced reactions, 3He + natAg in particular. The identification of the modulations involves a technique that subtracts the bulk statistical background from the measured alpha spectra, in order for the modulations to become visible in the residuals. Due to insufficient knowledge of the background spectra, however, the presented evidence should only be regarded as preliminary and tentative.

  14. Inverse kinematics technique for the study of fission-fragment isotopic yields at GANIL energies

    International Nuclear Information System (INIS)

    Delaune, O.

    2012-01-01

    The characteristics of the fission-products distributions result of dynamical and quantum properties of the deformation process of the fissioning nucleus. These distributions have also an interest for the conception of new nuclear power plants or for the transmutation of the nuclear wastes. Up to now, our understanding of the nuclear fission remains restricted because of experimental limitations. In particular, yields of the heavy fission products are difficult to get with precision. In this work, an innovative experimental technique is presented. It is based on the use of inverse kinematics coupled to the use of a spectrometer, in which a 238 U beam at 6 or 24 A MeV impinges on light targets. Several actinides, from 238 U to 250 Cf, are produced by transfer or fusion reactions, with an excitation energy ranges from ten to few hundreds MeV depending on the reaction and the beam energy. The fission fragments of these actinides are detected by the VAMOS spectrometer or the LISE separator. The isotopic yields of fission products are completely measured for different fissioning systems. The neutron excess of the fragments is used to characterise the isotopic distributions. Its evolution with excitation energy gives important insights on the mechanisms of the compound-nucleus formation and its deexcitation. Neutron excess is also used to determine the multiplicity of neutrons evaporated by the fragments. The role of the proton and neutron shell effects into the formation of fission fragments is also discussed. (author) [fr

  15. Utilization of fast reactor excess neutrons for burning minor actinides and long lived FPs

    International Nuclear Information System (INIS)

    Kawashima, K.; Kobayashi, K.; Kaneto, K.

    1995-01-01

    An evaluation is made on a large MOX fuel fast reactor's capability of burning minor actinides and long lived fission products (FPs) without imposing penalties on core nuclear and safety characteristics. The excess neutrons generated in the fast reactor core are fully utilized not only to generate the fissile material but also to transmute the minor actinides and long lived FPs. The FP target assemblies which consist of Tc-99 and I-129 are loaded into the selected blanket positions whereas the minor actinides are loaded to the rest of the blanket. A long term FP accumulation scenario is also considered in the mix of FP burner fast reactor and non-burner LWRs. (author)

  16. Ternary fission of spontaneously fissile uranium isomers excited by neutrons

    International Nuclear Information System (INIS)

    Makarenko, V.E.; Molchanov, Y.D.; Otroshchenko, G.A.; Yan'kov, G.B.

    1989-01-01

    Spontaneously fissile isomers (SFI) of uranium were excited in the reactions 236,238 U(n,n') at an average neutron energy 4.5 MeV. A pulsed electrostatic accelerator and time analysis of the fission events were used. Fission fragments were detected by the scintillation method, and long-range particles from fission were detected by an ionization method. The relative probability of fission of nuclei through a spontaneously fissile isomeric state was measured: (1.30±0.01)·10 -4 ( 236 U) and (1.48±0.02)·10 -4 ( 238 U). Half-lives of the isomers were determined: 121±2 nsec (the SFI 236 U) and 267±13 nsec (the SFI 238 U). In study of the ternary fission of spontaneously fissile isotopes of uranium it was established that the probability of the process amounts to one ternary fission per 163±44 binary fissions of the SFI 236 U and one ternary fission per 49±14 binary fissions of the SFI 238 U. The substantial increase of the probability of ternary fission of SFI of uranium in comparison with the case of ternary fission of nuclei which are not in an isomeric state may be related to a special nucleon configuration of the fissile isomers of uranium

  17. Fission fragment mass distribution in the 13C+182W and 176Yb reactions

    International Nuclear Information System (INIS)

    Ramachandran, K.; Hinde, D.J.; Dasgupta, M.; Williams, E.; Wakhle, A.; Luong, D.H.; Evers, M.; Carter, I.P.; Das, S.

    2014-01-01

    Fission fragment mass distributions have been measured for many systems and found to be asymmetric in the fission of nuclei with nucleon number A in the range 228-258 and proton number Z in the range 90-100. For lighter systems, it has been observed that fission fragment mass distributions are usually symmetric. At high excitation energies the shell effects are expected to vanish and the nuclei are expected to behave like a charged liquid drop; hence, only symmetric fission is expected for all the nuclei. Even after much experimental and theoretical work in this field, the rate of damping of shell effects with excitation energy is not well known. This abstract reports our measurements with 13 C beams on 182 W and 176 Yb targets

  18. Conservatism in the actinide-only burnup credit for PWR spent nuclear fuel packages

    International Nuclear Information System (INIS)

    Lancaster, D.B.; Rahimi, M.; Thornton, J.

    1996-01-01

    In May 1995, the U.S. Department of Energy (DOE) submitted a topical report to the U.S. Nuclear Regulatory Commission (NRC) to gain actinide-only burnup credit for spent nuclear fuel (SNF) storage, transportation, or disposal packages. After approval of this topical report, DOE intends further submittals to the NRC to acquire additional burnup credit (e.g., the topical does not use fission products and is limited to only the first 100 yr of disposal). The NRC has responded to the topical with its preliminary questions. To aid in evaluation of the method, a review of the conservatism in the actinide-only burnup credit methodology was performed. An overview of the actinide-only burnup credit methodology is presented followed by a summary of the conservatism

  19. Exploratory study of fission product yields of neutron-induced fission of 235U , 238U , and 239Pu at 8.9 MeV

    Science.gov (United States)

    Bhatia, C.; Fallin, B. F.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; Arnold, C. W.; Bond, E.; Bredeweg, T. A.; Fowler, M. M.; Moody, W.; Rundberg, R. S.; Rusev, G. Y.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

    2015-06-01

    Using dual-fission chambers each loaded with a thick (200 -400 -mg /c m2) actinide target of 235 ,238U or 239Pu and two thin (˜10 -100 -μ g /c m2) reference foils of the same actinide, the cumulative yields of fission products ranging from 92Sr to 147Nd have been measured at En= 8.9 MeV . The 2H(d ,n ) 3He reaction provided the quasimonoenergetic neutron beam. The experimental setup and methods used to determine the fission product yield (FPY) are described, and results for typically eight high-yield fission products are presented. Our FPYs for 235U(n ,f ) , 238U(n ,f ) , and 239Pu(n ,f ) at 8.9 MeV are compared with the existing data below 8 MeV from Glendenin et al. [Phys. Rev. C 24, 2600 (1981), 10.1103/PhysRevC.24.2600], Nagy et al. [Phys. Rev. C 17, 163 (1978), 10.1103/PhysRevC.17.163], Gindler et al. [Phys. Rev. C 27, 2058 (1983), 10.1103/PhysRevC.27.2058], and those of Mac Innes et al. [Nucl. Data Sheets 112, 3135 (2011), 10.1016/j.nds.2011.11.009] and Laurec et al. [Nucl. Data Sheets 111, 2965 (2010), 10.1016/j.nds.2010.11.004] at 14.5 and 14.7 MeV, respectively. This comparison indicates a negative slope for the energy dependence of most fission product yields obtained from 235U and 239Pu , whereas for 238U the slope issue remains unsettled.

  20. Fission fragment spins and spectroscopy

    International Nuclear Information System (INIS)

    Durell, J.L.

    1988-01-01

    Prompt γ-ray coincidence experiments have been carried out on γ-rays emitted from post-neutron emission fission fragments produced by the aup 19F + 197 Au and 18 O + 232 Th reactions. Decay schemes have been established for even-even nuclei ranging from 78 Se to 148 Nd. Many new states with spin up to ∼ 12h have been observed. Apart from providing a wealth of new information on the spectroscopy of neutron-rich nuclei, the data have been analyzed to determine the average spin of primary fission fragments as a function of fragment mass. The results suggest that the fragment spins are determined by the temperature and shape of the primary fragments at or near to scission

  1. Octupole correlation effects in nuclei

    International Nuclear Information System (INIS)

    Chasman, R.R.

    1992-01-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions

  2. Transmutation of radioactive nuclear waste – present status and ...

    Indian Academy of Sciences (India)

    Transmutation of long-lived actinides and fission products becomes an im- ... Similar approach was performed for sub critical fast reactor core with Pu/MA .... The same might be addressed to masses of nuclei (the use of experimental values.

  3. Fission barriers of superheavy nuclei

    International Nuclear Information System (INIS)

    Burvenich, T.

    2001-01-01

    Full text: Self consistent microscopic mean-field models are powerful tools for the description of nuclear structure phenomena in the region of known elements, where they have reached a good quality. Especially the Skyrme-Hartree-Fock (SHF) method and the Relativistic Mean-Field (RMF) model will be considered in the discussion of the properties of these models. When it comes to extrapolation to the region of superheavy elements, though there is agreement concerning the global trends, these model exhibit significant differences in their predictions concerning fission barrier heights and structures. (Author)

  4. Production of actinide nuclei by multi-nucleon transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Ahmad, I.; Carpenter, M.P. [and others

    1995-08-01

    Multi-nucleon transfers have increasingly allowed us to reach parts of the nuclear chart where regular compound nuclear reactions are prohibited. The interesting region of Ra and Rn, where a rich tapestry of nuclear structure manifests itself, is now accessible using this technique of deep inelastic scattering. In particular, these nuclei are predicted to lie at the onset of octupole deformation and the region is rich in examples of shape coexistence. There are several theoretical predictions of nuclear structure of these nuclei that have not been experimentally tested. Moreover, there is serious disagreement among these theories. We used a beam of {sup 136}Xe at 720 MeV from ATLAS on a target of {sup 232}Th to produce a range of Rn isotopes, with a mass from 220 to 224, and Ra isotopes with masses greater than 222. The beam energy, target and beam were selected carefully to enhance the cross-section for production of these nuclei and reduce the Doppler broadening of the gamma rays that were observed in the Argonne Notre Dame gamma-ray facility. The 12 germanium detectors of this array allowed the observation of gamma-gamma coincidences. The inner ball of 50 BGO detectors allowed us to record the multiplicity and sum-energy information for each event. The latter should permit us to determine the entry region in the products of the transfer reaction. We had four successful days of beam-time, when we collected in excess of 8 x 10{sup 7} events. Data analysis is in progress at the University of Liverpool. A complete set of spectroscopic information on the yrast structure of the many nuclei produced in this reaction is being extracted.

  5. Actinide recycle potential in the Integral Fast Reactor (IFR) fuel cycle

    International Nuclear Information System (INIS)

    Chang, Y.I.; Till, C.E.

    1990-01-01

    In the Integral Fast Reactor (IFR) development program, the entire reactor system -- reactor, fuel cycle, and waste process is being developed and optimized at the same time as a single integral entity. The use of metallic fuel in the IFR allows a radically improved fuel cycle technology. Pyroprocessing, which utilizes high temperatures and molten salt and molten metal solvents, can be advantageously utilized for processing metal fuels because the product is metal suitable for fabrication into new fuel elements. The key step in the IFR process is electrorefining, which provides for recovery of the valuable fuel constituents, uranium and plutonium, and for removal of fission products. In the electrorefining operation, uranium and plutonium are selectively transported from an anode to a cathode, leaving impurity elements, mainly fission products, either in the anode compartment or in a molten salt electrolyte. A notable feature of the IFR process is that the actinide elements accompany plutonium through the process. This results in a major advantage in the high-level waste management, because these actinides are automatically recycled back into the reactor for in-situ burning. Based on the recent IFR process development, a preliminary assessment has also been made to investigate the feasibility of further adapting the pyrochemical processes to directly extract actinides from LWR spent fuel. The results of this assessment indicate very promising potential and two most promising flowsheet options have been identified for further research and development. This paper also summarizes current thinking on the rationale for actinide recycle, its ramifications on the geologic repository and the current high-level waste management plans, and the necessary development programs. 5 refs., 4 figs., 4 tabs

  6. Pion-induced fission of 209Bi and 119Sn: measurements, calculations, analyses and comparison

    International Nuclear Information System (INIS)

    Rana, M.A.; Sher, G.; Manzoor, S.; Shehzad, M.I.

    2011-01-01

    Cross-sections for the π - -induced fission of 209 Bi and 119 Sn have been measured using the most sensitive CR-39 solid-state nuclear track detector. In experiments, target–detector stacks were exposed to negative pions of energy 500, 672, 1068, and 1665 MeV at the Brookhaven National Laboratory, USA. An important aspect of the present paper is the comparison of pion-induced fission fragment spectra of above mentioned nuclei with the spontaneous fission fragment spectra of 252 Cf. This comparison is made in terms of fission fragment track lengths in the CR-39 detectors. Measurement results are compared with calculations of Monte Carlo and statistical weight functions methods using the computer code CEM95. Agreement between measurements and calculations is fairly good for 209 Bi target nuclei whereas it is indigent for the case of 119 Sn. The possibilities of the trustworthy calculations, using the computer code CEM95, comparable with measurements of pion-induced fission in intermediate and heavy nuclei are explored by employing various systematics available in the code. Energy dependence of pion-induced fission in 119 Sn and 209 Bi is analyzed employing a newly defined parameter geometric-size-normalized fission cross-section (χ f g ). It is found that the collective nuclear excitations, which may lead to fission, become more probable for both 209 Bi and 119 Sn nuclei with increasing energy of negative pions from 500 to 1665 MeV. (author)

  7. Nuclear data of the major actinide fuel materials

    Energy Technology Data Exchange (ETDEWEB)

    Poenitz, W.P.; Saussure, G. De

    1984-01-01

    The effect of nuclear data of the major actinide fuel materials on the design accuracy, economics and safety of nuclear power systems is discussed. Since most of the data are measured relative to measurement standards, in particular the fission cross-section of /sup 235/U, data must be examined to ensure that absolute measurements and relative measurements are correctly handled. Nuclear data of fissile materials, fertile materials and minor plutonium isotopes are discussed.

  8. Demonstration of pyropartitioning process by using genuine high-level liquid waste. Reductive-extraction of actinide elements from chlorination product

    International Nuclear Information System (INIS)

    Uozumi, Koichi; Iizuka, Masatoshi; Kurata, Masaki; Ougier, Michel; Malmbeck, Rikard; Winckel, Stefaan van

    2009-01-01

    The pyropartitioning process separates the minor actinide elements (MAs) together with uranium and plutonium from the high-level liquid waste generated at the Purex reprocessing of spent LWR fuel and introduces them to metallic fuel cycle. For the demonstration of this technology, a series experiment using 520g of genuine high-level liquid waste was started and the conversion of actinide elements to their chlorides was already demonstrated by denitration and chlorination. In the present study, a reductive extraction experiment in molten salt/liquid cadmium system to recover actinide elements from the chlorination product of the genuine high-level liquid waste was performed. The results of the experiment are as following; 1) By the addition of the cadmium-lithium alloy reductant, almost all of plutonium and MAs in the initial high-level liquid waste were recovered in the cadmium phase. It means no mass loss during denitration, chlorination, and reductive-extraction. 2) The separation factor values of plutonium, MAs, and rare-earth fission product elements versus uranium agreed with the literature values. Therefore, actinide elements will be separated from fission product elements in the actual system. Hence, the pyropartitioning process was successfully demonstrated. (author)

  9. The ASIND-MEPhI library of independent actinide fission product yields

    International Nuclear Information System (INIS)

    Bogomolova, E.S.; Grashin, A.F.; Efimenko, A.D.; Lukasevich, I.B.

    1997-01-01

    This data base of independent fission product yields has been set up at the Moscow Engineering Physics Institute on the basis of theoretical calculations within the framework of the super-nonequilibrium thermodynamic model. The database consists of independent yield sets for 1163 fission products in the wide range of fissile nuclides from thorium-229 to fermium-257 with excitation energies up to 20 MeV. The use of the theoretical model made it possible to raise the accuracy of prediction for poorly explored fission reactions. The number of yield sets is larger than in the ENDF/B. For example, photofission product yields are included in the ASIND-MEPhI database as virtual sets. (author). 14 refs, 17 figs, 2 tabs

  10. Structural study and properties of peraluminous formulations for the fission products and minor actinides confinement

    International Nuclear Information System (INIS)

    Gasnier, E.

    2013-01-01

    In this work, peraluminous glasses (lack of alkaline and alkaline earth ions regarding aluminum) are under study to assess the potentiality of these matrices to confine fission products and minor actinides (FPA) at higher rate than current R7T7 glass (18,5 wt % FPA). The first part of this work aims at studying the physical and chemical properties of complex peraluminous glasses containing increasing FPA rate (18.5 to 32 wt %) to compare them with the specifications. The very low crystallization tendency of complex glasses containing up to 22.5 wt % as well as the very good chemical durability observed are major assets. The other part focuses on the lanthanides incorporation in simplified glass compositions in the SiO 2 -B 2 O 3 -Al 2 O 3 -Na 2 O-CaO-Ln 2 O 3 system (Ln = Nd or La). The glass homogeneity and devitrification tendency are investigated at different scales by XRD, SEM, TEM and structural techniques such as NMR (MAS, MQMAS, REDOR, HMQC, DHMQC) and neodymium optical spectroscopy that appear very powerful to determine the lanthanides structural role regarding aluminum and describe more precisely the structural organization of peraluminous network, as still unknown in such systems. The glass homogeneity was demonstrated in a large composition domain and new structural data were put in evidence at high lanthanides content. (author) [fr

  11. Nuclear Data for Reactor Physics: Cross sections and level densities in the actinide region

    Directory of Open Access Journals (Sweden)

    Bernstein L.

    2010-03-01

    Full Text Available Nuclear data in the actinide region are particularly important because they are basis behind all simulations of nuclear reactor core behaviour over both long time scales (fuel depletion and waste production and short time scales (accident scenarios. Nuclear reaction cross sections must be known as precisely as possible so that core reaction rates can be accurately calculated. Although cross section measurements in this region have been widely performed, for certain nuclei, particularly those with short half lives, direct measurements are either very difficult or impossible and thus reactor simulations must rely on theoretical calculations or extrapolations from neighbouring nuclei. The greatest uncertainty in theoretical cross section calculations comes from the lack of knowledge of level densities, for which predicted values can often be incorrect by a factor of two or more. Therefore there is a strong case for a systematic experimental study of level densities in the actinide region for the purpose of a providing a stringent test of theoretical cross section calculations for nuclei where experimental cross section data are available and b for providing better estimations of cross sections for nuclei in which no cross section data are available.

  12. Response of actinides to flux changes in high-flux systems

    International Nuclear Information System (INIS)

    Sailor, W.C.

    1993-01-01

    When discussing the transmutation of actinides in accelerator-based transmutation of waste (ATW) systems, there has been some concern about the dynamics of the actinides under high transient fluxes. For a pure neptunium feed, it has been estimated that the 238 Np/ 237 Np ratio increase due to an increasing flux may lead to an unstable, positive reactivity growth. In this analysis, a perturbation method is used to calculate the response of the entire set of actinides in a general way that allows for more species than just neptunium. The time response of the system can be calculated; i.e., a plot of fuel composition and reactivity versus time after a change in flux can be made. The effects of fission products can also be included. The procedure is extremely accurate on short time scales (∼ 1000 s) for the flux levels we contemplate. Calculational results indicate that the reactivity insertions are always smaller than previously estimated

  13. Accelerator-driven thermal fission systems may provide energy supply advantages

    International Nuclear Information System (INIS)

    Linford, R.K.

    1992-01-01

    This presentation discusses the energy supply advantages of using accelerator-driven thermal fission systems. Energy supply issues as related to cost, fuel supply stability, environmental impact, and safety are reviewed. It is concluded that the Los Alamos Accelerator Transmutation of Waste (ATW) concept, discussed here, has the following advantages: improved safety in the form of low inventory and subcriticality; reduced high-level radioactive waste management timescales for both fission products and actinides; and a very long-term fuel supply requiring no enrichment

  14. Energy partition in nuclear fission

    International Nuclear Information System (INIS)

    Ruben, A.; Maerten, H.; Seeliger, D.

    1990-01-01

    A scission point model (two spheroid model TSM) including semi-empirical temperature-dependent shell correction energies for deformed fragments at scission is presented. It has been used to describe the mass-asymmetry-dependent partition of the total energy release on both fragments from spontaneous and induced fission. Characteristic trends of experimental fragment energy and neutron multiplicity data as function of incidence energy in the Th-Cf region of fissioning nuclei are well reproduced. Based on model applications, information on the energy dissipated during the descent from second saddle of fission barrier to scission point have been deduced. (author). 39 refs, 13 figs

  15. Description of deformed nuclei in the sdg boson model

    Energy Technology Data Exchange (ETDEWEB)

    Li, S.C. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences; Kuyucak, S. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1996-07-15

    We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical 1/N expansion techniques. The focus is on the description of high-spin states which have recently become computationally accessible through the use of computer algebra in the 1/N expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei. (orig.).

  16. Description of deformed nuclei in the sdg boson model

    Science.gov (United States)

    Li, S. C.; Kuyucak, S.

    1996-02-01

    We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical {1}/{N} expansion techniques. The focus is on the description of high-spin states which have recently become computationally accessible through the use of computer algebra in the {1}/{N} expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei.

  17. Description of deformed nuclei in the sdg boson model

    International Nuclear Information System (INIS)

    Li, S.C.; Kuyucak, S.

    1996-01-01

    We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical 1/N expansion techniques. The focus is on the description of high-spin states which have recently become computationally accessible through the use of computer algebra in the 1/N expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei. (orig.)

  18. Evidence for two-dimensional ising structure in atomic nuclei

    International Nuclear Information System (INIS)

    MacGregor, M.H.

    1976-01-01

    Although the unpaired nucleons in an atomic nucleus exhibit pronounced shell-model-like behavior, the situation with respect to the paired-off ''core region'' nucleons is considerably more obscure. Several recent ''multi-alpha knockout'' and ''quasi-fission'' experiments indicate that nucleon clustering is prevalent throughout the core region of the nucleus; this same conclusion is suggested by nuclear-binding-energy systematics, by the evidence for a ''neutron halo'' in heavy nuclei and by the magnetic-moment systematics of low-mass odd-A nuclei. A number of arguments suggests, in turn, that this nucleon clustering is not spherical or spheroidal in shape, as has generally been assumed, but instead is in the form of two-dimensional Ising-like layers, with the layers arrayed perpendicular to the symmetry axis of the nucleus. The effects of this two-dimensional layering are observed most clearly in low-energy-induced fission, where nuclei with an even (odd) number of Ising layers fission symmetrically (asymmetrically). This picture of the nucleus gives an immediate quantitative explanation for the observed asymmetry in the fission of uranium, and also for the transition from symmetric to asymmetric and back to symmetric fission as the atomic number of the fissioning nuclues increase from A = 197 up to A = 258. These results suggest that, in the shell model formulation of the atomic nucleus, the basis states for the paired-off nucleon core region should be modified so as to contain laminar nucleon cluster correlations

  19. Fission excitation function for 19F + 194,196,198Pt at near and above barrier energies

    Directory of Open Access Journals (Sweden)

    Singh Varinderjit

    2015-01-01

    Full Text Available Fission excitation functions for 19F + 194,196,198Pt reactions populating 213,215,217Fr compound nuclei are reported. Out of these three compound nuclei, 213Fr is a shell closed (N=126 compound nucleus and the other two are away from the shell closure. From a comparison of the experimental fission cross-sections with the statistical model predictions, it is observed that the fission cross-sections are underestimated by the statistical model predictions using shell corrected finite range rotating liquid drop model (FRLDM fission barriers. Further the FRLDM fission barriers are reduced to fit the fission cross-sections over the entire measured energy range.

  20. Characterization and development of an active scintillating target for nuclear reaction studies on actinides

    Energy Technology Data Exchange (ETDEWEB)

    Belier, Gilbert, E-mail: gilbert.belier@cea.fr [CEA, DAM, DIF, DPTA, Centre du Grand Rue, 91297 Arpajon (France); Aupiais, Jean; Varignon, Cyril; Vayre, Sylvain [CEA, DAM, DIF, DPTA, Centre du Grand Rue, 91297 Arpajon (France)

    2012-02-01

    This article presents the development of a new kind of active actinide target, based on organic liquid scintillators containing the dissolved isotope. Amongst many advantages one can mention the very high detection efficiency, the Pulse Shape Discrimination capability, the fast response allowing high count rates and good time resolution and the ease of fabrication. The response of this target to fission fragments has been studied. The discrimination of alpha, fission and proton recoil events is demonstrated. The alpha decay and fission detection efficiencies are simulated and compared to measurements. Finally the use of such a target in the context of fast neutron induced reactions is discussed.

  1. Characterization and development of an active scintillating target for nuclear reaction studies on actinides

    International Nuclear Information System (INIS)

    Belier, Gilbert; Aupiais, Jean; Varignon, Cyril; Vayre, Sylvain

    2012-01-01

    This article presents the development of a new kind of active actinide target, based on organic liquid scintillators containing the dissolved isotope. Amongst many advantages one can mention the very high detection efficiency, the Pulse Shape Discrimination capability, the fast response allowing high count rates and good time resolution and the ease of fabrication. The response of this target to fission fragments has been studied. The discrimination of alpha, fission and proton recoil events is demonstrated. The alpha decay and fission detection efficiencies are simulated and compared to measurements. Finally the use of such a target in the context of fast neutron induced reactions is discussed.

  2. Supercritical fluid carbon dioxide extraction of actinides

    International Nuclear Information System (INIS)

    Rao, Ankita; Tomar, B.S.

    2016-01-01

    Supercritical fluid extraction (SFE) is a process akin to liquid-liquid or solvent extraction where a Supercritical fluid (SCF) is contacted with a solid/ liquid matrix for the purpose of separating the component of interest from the original matrix. Carbon dioxide is a preferred choice as supercritical fluid (SCF) owing to its moderate critical parameter (P c = 7.38 MPa and T c = 304.1K) coupled with radiation and chemical stability, non toxic nature and low cost. Despite widespread applications for extraction of organic compounds and associated advantages especially liquid waste minimization, the SFE of metal ions was left unexplored for quite some time, as direct metal ion extraction is inefficient due charge neutralization requirement and weak solute-solvent interaction. Neutral SCF soluble metal-ligand complexation is imperative and SFE of actinides was reported only in 1994. Several studies have been carried out on SFE of uranium, thorium and plutonium from nitric acid medium employing different sets of ligands (organophosphorus, diketones, amides). Especially attractive is the possibility of direct dissolution and extraction of actinides employing ligand-acid adducts (like TBP.HNO 3 adduct) from solid matrices of different stages of nuclear fuel cycle viz. ores, spent nuclear fuels and radioactive wastes. Also, partitioning of actinides from fission products has been explored in spent nuclear fuel. These studies on supercritical fluid extraction of actinides indicate a more efficient and environmentally sustainable technology. (author)

  3. Influence of the bud neck on nuclear envelope fission in Saccharomyces cerevisiae.

    Science.gov (United States)

    Melloy, Patricia G; Rose, Mark D

    2017-09-15

    Studies have shown that nuclear envelope fission (karyokinesis) in budding yeast depends on cytokinesis, but not distinguished whether this was a direct requirement, indirect, because of cell cycle arrest, or due to bud neck-localized proteins impacting both processes. To determine the requirements for karyokinesis, we examined mutants conditionally defective for bud emergence and/or nuclear migration. The common mutant phenotype was completion of the nuclear division cycle within the mother cell, but karyokinesis did not occur. In the cdc24 swe1 mutant, at the non-permissive temperature, multiple nuclei accumulated within the unbudded cell, with connected nuclear envelopes. Upon return to the permissive temperature, the cdc24 swe1 mutant initiated bud emergence, but only the nucleus spanning the neck underwent fission suggesting that the bud neck region is important for fission initiation. The neck may be critical for either mechanical reasons, as the contractile ring might facilitate fission, or for regulatory reasons, as the site of a protein network regulating nuclear envelope fission, mitotic exit, and cytokinesis. We also found that 77-85% of pairs of septin mutant nuclei completed nuclear envelope fission. In addition, 27% of myo1Δ mutant nuclei completed karyokinesis. These data suggested that fission is not dependent on mechanical contraction at the bud neck, but was instead controlled by regulatory proteins there. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Systematics of Fission-Product Yields

    International Nuclear Information System (INIS)

    Wahl, A.C.

    2002-01-01

    Empirical equations representing systematics of fission-product yields have been derived from experimental data. The systematics give some insight into nuclear-structure effects on yields, and the equations allow estimation of yields from fission of any nuclide with atomic number Z F = 90 thru 98, mass number A F = 230 thru 252, and precursor excitation energy (projectile kinetic plus binding energies) PE = 0 thru ∼200 MeV--the ranges of these quantities for the fissioning nuclei investigated. Calculations can be made with the computer program CYFP. Estimates of uncertainties in the yield estimates are given by equations, also in CYFP, and range from ∼ 15% for the highest yield values to several orders of magnitude for very small yield values. A summation method is used to calculate weighted average parameter values for fast-neutron (∼ fission spectrum) induced fission reactions

  5. Systematics of Fission-Product Yields

    Energy Technology Data Exchange (ETDEWEB)

    A.C. Wahl

    2002-05-01

    Empirical equations representing systematics of fission-product yields have been derived from experimental data. The systematics give some insight into nuclear-structure effects on yields, and the equations allow estimation of yields from fission of any nuclide with atomic number Z{sub F} = 90 thru 98, mass number A{sub F} = 230 thru 252, and precursor excitation energy (projectile kinetic plus binding energies) PE = 0 thru {approx}200 MeV--the ranges of these quantities for the fissioning nuclei investigated. Calculations can be made with the computer program CYFP. Estimates of uncertainties in the yield estimates are given by equations, also in CYFP, and range from {approx} 15% for the highest yield values to several orders of magnitude for very small yield values. A summation method is used to calculate weighted average parameter values for fast-neutron ({approx} fission spectrum) induced fission reactions.

  6. Actinide production in 136Xe bombardments of 249Cf

    International Nuclear Information System (INIS)

    Gregorich, K.E.

    1985-08-01

    The production cross sections for the actinide products from 136 Xe bombardments of 249 Cf at energies 1.02, 1.09, and 1.16 times the Coulomb barrier were determined. Fractions of the individual actinide elements were chemically separated from recoil catcher foils. The production cross sections of the actinide products were determined by measuring the radiations emitted from the nuclides within the chemical fractions. The chemical separation techniques used in this work are described in detail, and a description of the data analysis procedure is included. The actinide production cross section distributions from these 136 Xe + 249 Cf bombardments are compared with the production cross section distributions from other heavy ion bombardments of actinide targets, with emphasis on the comparison with the 136 Xe + 248 Cm reaction. A technique for modeling the final actinide cross section distributions has been developed and is presented. In this model, the initial (before deexcitation) cross section distribution with respect to the separation energy of a dinuclear complex and with respect to the Z of the target-like fragment is given by an empirical procedure. It is then assumed that the N/Z equilibration in the dinuclear complex occurs by the transfer of neutrons between the two participants in the dinuclear complex. The neutrons and the excitation energy are statistically distributed between the two fragments using a simple Fermi gas level density formalism. The resulting target-like fragment initial cross section distribution with respect to Z, N, and excitation energy is then allowed to deexcite by emission of neutrons in competition with fission. The result is a final cross section distribution with respect to Z and N for the actinide products. 68 refs., 33 figs., 6 tabs

  7. Ionic Liquid and Supercritical Fluid Hyphenated Techniques for Dissolution and Separation of Lanthanides, Actinides, and Fission Products

    International Nuclear Information System (INIS)

    Wai, Chien M.; Mincher, Bruce

    2012-01-01

    This project is investigating techniques involving ionic liquids (IL) and supercritical (SC) fluids for dissolution and separation of lanthanides, actinides, and fission products. The research project consists of the following tasks: Study direct dissolution of lanthanide oxides, uranium dioxide and other actinide oxides in [bmin][Tf 2 N] with TBP(HNO 3 ) 1.8 (H 2 O) 0.6 and similar types of Lewis acid-Lewis base complexing agents; Measure distributions of dissolved metal species between the IL and the sc-CO 2 phases under various temperature and pressure conditions; Investigate the chemistry of the dissolved metal species in both IL and sc-CO 2 phases using spectroscopic and chemical methods; Evaluate potential applications of the new extraction techniques for nuclear waste management and for other projects. Supercritical carbon dioxide (sc-CO 2 ) and ionic liquids are considered green solvents for chemical reactions and separations. Above the critical point, CO 2 has both gas- and liquid-like properties, making it capable of penetrating small pores of solids and dissolving organic compounds in the solid matrix. One application of sc-CO 2 extraction technology is nuclear waste management. Ionic liquids are low-melting salts composed of an organic cation and an anion of various forms, with unique properties making them attractive replacements for the volatile organic solvents traditionally used in liquid-liquid extraction processes. One type of room temperature ionic liquid (RTIL) based on the 1-alkyl-3-methylimidazolium cation [bmin] with bis(trifluoromethylsulfonyl)imide anion [Tf 2 N] is of particular interest for extraction of metal ions due to its water stability, relative low viscosity, high conductivity, and good electrochemical and thermal stability. Recent studies indicate that a coupled IL sc-CO 2 extraction system can effectively transfer trivalent lanthanide and uranyl ions from nitric acid solutions. Advantages of this technique include operation at

  8. Detailed studies of Minor Actinide transmutation-incineration in high-intensity neutron fluxes

    International Nuclear Information System (INIS)

    Bringer, O.; Al Mahamid, I.; Blandin, C.; Chabod, S.; Chartier, F.; Dupont, E.; Fioni, G.; Isnard, H.; Letourneau, A.; Marie, F.; Mutti, P.; Oriol, L.; Panebianco, S.; Veyssiere, C.

    2006-01-01

    The Mini-INCA project is dedicated to the measurement of incineration-transmutation chains and potentials of minor actinides in high-intensity thermal neutron fluxes. In this context, new types of detectors and methods of analysis have been developed. The 241 Am and 232 Th transmutation-incineration chains have been studied and several capture and fission cross sections measured very precisely, showing some discrepancies with existing data or evaluated data. An impact study was made on different based-like GEN-IV reactors. It underlines the necessity to proceed to precise measurements for a large number of minor-actinides that contribute to these future incineration scenarios. (authors)

  9. Detailed studies of Minor Actinide transmutation-incineration in high-intensity neutron fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Bringer, O. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Al Mahamid, I. [Lawrence Berkeley National Laboratory, E.H. and S. Div., CA (United States); Blandin, C. [CEA/Cadarache/DEN/DER/SPEX, Saint-Paul-lez-Durances (France); Chabod, S. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Chartier, F. [CEA/Cadarache/DEN/DPC/SECR, Gif-sur-Yvette (France); Dupont, E.; Fioni, G. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Isnard, H. [CEA/Cadarache/DEN/DPC/SECR, Gif-sur-Yvette (France); Letourneau, A.; Marie, F. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France); Mutti, P. [Institut Laue-Langevin, Grenoble (France); Oriol, L. [CEA/Cadarache/DEN/DER/SPEX, Saint-Paul-lez-Durances (France); Panebianco, S.; Veyssiere, C. [CEA/Saclay/DSM/DAPNIA, Gif-sur-Yvette (France)

    2006-07-01

    The Mini-INCA project is dedicated to the measurement of incineration-transmutation chains and potentials of minor actinides in high-intensity thermal neutron fluxes. In this context, new types of detectors and methods of analysis have been developed. The {sup 241}Am and {sup 232}Th transmutation-incineration chains have been studied and several capture and fission cross sections measured very precisely, showing some discrepancies with existing data or evaluated data. An impact study was made on different based-like GEN-IV reactors. It underlines the necessity to proceed to precise measurements for a large number of minor-actinides that contribute to these future incineration scenarios. (authors)

  10. Proceedings of the specialists' meeting on interdisciplinary approach to nuclear fission 1998

    International Nuclear Information System (INIS)

    Nakagome, Yoshihiro

    1999-02-01

    One of the prominent features of nuclear fission phenomena distinguished from other reactions consists in its many-facet nature. This includes interesting problems in nuclear physics like stability and properties of transactinide and superheavy nuclei, macroscopic and microscopic effects in large-amplitude deformation process, partition of mass and energy at scission, formation of neutron-rich nuclei, neutron- and gamma-ray emission from highly excited states and so on. These aspects are intriguing not only from scientific point of view but also from technological one, because knowledge and understanding of the essential features of the phenomena forms the basis of application of nuclear energy. Physicists expect to obtain a deeper insight into fundamental problems in subjects such as relation between fission process and fusion of heavy-ions, statistical and dynamical processes in nuclear reactions, level structure and decay modes of highly-excited nuclei. On the other hand, there are still continued requests from scientists in nuclear engineering for more accurate data for transuranium nuclei and fission products, as well as for fundamental constants, like fission cross sections, multiplicity and spectra of prompt and delayed neutrons, and other physical quantities that are important in reactor physics. Studies on properties of neutron-rich nuclei are conducted under double interests: one from nucleosynthesis in the universe, another from nuclear incineration of fission products. We considered that these many-facet nature of the fission phenomena should be the central idea of the Specialists' Meeting itself. This implies that we intended to devise a common place where people from different fields encounter, discuss together, exchange ideas and hopefully find good suggestions for pursuing further studies. We are sure that such a meeting, really rare and unique in academic communities in our country, should serve to vitalize research activities relevant to fission

  11. The wastes of nuclear fission; Les dechets de la fission nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Doubre, H. [Paris-11 Univ., Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, IN2P3/CNRS, 91 - Orsay (France)

    2005-07-01

    In this paper the author presents the problems of the radioactive wastes generated by the nuclear fission. The first part devoted to the fission phenomenon explains the incident neutron energy and the target nuclei role. The second part devoted to the nuclear wastes sources presents the production of wastes upstream of the reactors, in the reactors and why these wastes are dangerous. The third part discusses the radioactive wastes management in France (classification, laws). The last part details the associated research programs: the radionuclides separation, the disposal, the underground storage, the transmutation and the thorium cycle. (A.L.B.)

  12. Fission Product Yields from {sup 232}Th, {sup 238}U, and {sup 235}U Using 14 MeV Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Pierson, B.D., E-mail: bpnuke@umich.edu [Department of Nuclear Engineering Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48109 (United States); Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Greenwood, L.R. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States); Flaska, M. [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, 227 Reber Bldg., University Park, PA 16802 (United States); Pozzi, S.A. [Department of Nuclear Engineering Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48109 (United States)

    2017-01-15

    Neutron-induced fission yield studies using deuterium-tritium fusion-produced 14 MeV neutrons have not yet directly measured fission yields from fission products with half-lives on the order of seconds (far from the line of nuclear stability). Fundamental data of this nature are important for improving and validating the current models of the nuclear fission process. Cyclic neutron activation analysis (CNAA) was performed on three actinide targets–thorium-oxide, depleted uranium metal, and highly enriched uranium metal–at the University of Michigan's Neutron Science Laboratory (UM-NSL) using a pneumatic system and Thermo-Scientific D711 accelerator-based fusion neutron generator. This was done to measure the fission yields of short-lived fission products and to examine the differences between the delayed fission product signatures of the three actinides. The measured data were compared against previously published results for {sup 89}Kr, −90, and −92 and {sup 138}Xe, −139, and −140. The average percent deviation of the measured values from the Evaluated Nuclear Data Files VII.1 (ENDF/B-VII.1) for thorium, depleted-uranium, and highly-enriched uranium were −10.2%, 4.5%, and −12.9%, respectively. In addition to the measurements of the six known fission products, 23 new fission yield measurements from {sup 84}As to {sup 146}La are presented.

  13. Local structure near actinides and nucleating elements in borosilicate glass for nuclear industry: Results of X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Petit-Maire, D.

    1988-01-01

    Possibilities and limits of X-ray absorption spectroscopy for cation site description in silicate glasses and possible applications for complex glasses, like glass for fission product containment, are examined. In borosilicate glasses two types of sites are evidenced for actinides at the valence 4: Coordinance 6 sites with a narrow radial distribution for the distance An-0; higher coordination (7, 8 or more) with a wider and asymmetrical radial distribution. Proportion of low coordinance sites increases when cation size decreases (Th > Np). U and Np VI and V are characterized as actinyles with a chain 0-An-0 practically linear, coordinance in a plane perpendicular to this complex is probably 5. X-ray absorption spectroscopy allows an accurate description of actinide sites in fission product glasses [fr

  14. Neutron scattering on deformed nuclei

    International Nuclear Information System (INIS)

    Hansen, L.F.; Haight, R.C.; Pohl, B.A.; Wong, C.; Lagrange, C.

    1984-09-01

    Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9 Be, C, 181 Ta, 232 Th, 238 U and 239 Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonable good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP

  15. Chemical and Ceramic Methods Toward Safe Storage of Actinides

    International Nuclear Information System (INIS)

    P.E.D. Morgan; R.M. Housley; J.B. Davis; M.L. DeHaan

    2005-01-01

    A very important, extremely-long-term, use for monazite as a radwaste encapsulant has been proposed. The use of ceramic La-monazite for sequestering actinides (isolating them from the environment), especially plutonium and some other radioactive elements (e.g., fission-product rare earths), had been especially championed by Lynn Boatner of ORNL. Monazite may be used alone or, copying its compatibility with many other minerals in nature, may be used in diverse composite combinations

  16. SOURCES-3A: A code for calculating (α, n), spontaneous fission, and delayed neutron sources and spectra

    International Nuclear Information System (INIS)

    Perry, R.T.; Wilson, W.B.; Charlton, W.S.

    1998-04-01

    In many systems, it is imperative to have accurate knowledge of all significant sources of neutrons due to the decay of radionuclides. These sources can include neutrons resulting from the spontaneous fission of actinides, the interaction of actinide decay α-particles in (α,n) reactions with low- or medium-Z nuclides, and/or delayed neutrons from the fission products of actinides. Numerous systems exist in which these neutron sources could be important. These include, but are not limited to, clean and spent nuclear fuel (UO 2 , ThO 2 , MOX, etc.), enrichment plant operations (UF 6 , PuF 4 , etc.), waste tank studies, waste products in borosilicate glass or glass-ceramic mixtures, and weapons-grade plutonium in storage containers. SOURCES-3A is a computer code that determines neutron production rates and spectra from (α,n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides in homogeneous media (i.e., a mixture of α-emitting source material and low-Z target material) and in interface problems (i.e., a slab of α-emitting source material in contact with a slab of low-Z target material). The code is also capable of calculating the neutron production rates due to (α,n) reactions induced by a monoenergetic beam of α-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The (α,n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay α-particle spectra, 24 sets of measured and/or evaluated (α,n) cross sections and product nuclide level branching fractions, and functional α-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an

  17. Level Densities in the actinide region and indirect n,y cross section measurements using the surrogate method

    Directory of Open Access Journals (Sweden)

    Wiedeking M.

    2012-02-01

    Full Text Available Results from a program of measurements of level densities and gamma ray strength functions in the actinide region are presented. Experiments at the Oslo cyclotron involving the Cactus/Siri detectors and 232Th(d,x and 232Th(3He,x reactions were carried out to help answer the question of which level density model is the most appropriate for actinide nuclei, since it will have an impact on cross section calculations important for reactor physics simulations. A new technique for extracting level densities and gamma ray strength functions from particle-gamma coincidence data is proposed and results from the development of this technique are presented. In addition, simultaneous measurements of compound nuclear gamma decay probabilities have been performed for the key thorium cycle nuclei 233Th, 231Th and 232Pa up to around 1MeV above the neutron binding energy and have enabled extraction of indirect neutron induced capture cross sections for the 232Th, 231Pa and 230Th nuclei using the surrogate reaction method. Since the neutron capture cross section for 232Th is already well known from direct measurements a comparison provides a stringent test of the applicability of the surrogate technique in the actinide region.

  18. Intercomparison of derived integral data from evaluated data libraries of the actinides

    International Nuclear Information System (INIS)

    Paviotti Corcuera, R.

    1988-12-01

    Resonance integrals and fission spectrum averaged cross-sections are calculated for the actinides from all recent major evaluated libraries. Whenever possible the results are compared against measurements. It is found that the experimental data are scarce and that there exist considerable differences between experimentally measured data and those derived from the evaluated libraries. (author). 93 refs and tabs

  19. Fission - track age of the Marjalahti Pallasite

    International Nuclear Information System (INIS)

    Bondar, Yu.V.; Perelygin, V.P.

    2006-01-01

    Full text: Investigation of fossil charged-particle tracks in various mineral phases of extraterrestrial samples is a powerful method for research the early stages of the solar system. Over geological time, meteorites crystals have accumulated a record of tracks produced by heavily charged energetic particles from both internal (spontaneous fission of 238U and some other extinct isotopes) and external sources (galactic cosmic rays with Z>20). The fortunate fact that meteorite grains can accumulate latent and very long-lived tracks since soon after the end of nucleosynthesis in the solar nebula enables one to decode their radiation history and to detect any thermal events in the meteorite cosmic history by revealing these tracks through suitable etching procedures. Only a few minerals in meteorites (mainly phosphates) contain small amount of uranium; the fact that 238 U undergoes fission with fission-decay constant λ f ∼ 8.2x10 -17 yr -1 allows one to use this isotope as a chronometer. By measuring the U concentration in the crystals (by reactor irradiation) and the density of the spontaneous-fission tracks it is relatively easy to calculate the 'fission-track age' if 238 U is the main source of fission tracks. However the fission-track dating of extraterrestrial samples compared with the terrestrial ones has some peculiar features due to presence of a number of other potential track sources except the spontaneous fission of 238 U, such as the spontaneous fission of presently extinct 244 Pu, heavy nuclei of cosmic rays and induced fission by cosmic ray primaries. Only tracks from the spontaneous fission of U and Pu are suitable for fission-track dating. The competing effects of these fissioning elements, whose half-lives differ by a factor of ∼50, form a basis for a fission-track chronology for samples older than ∼ 4.0 Gyr. Over small intervals in time (∼ few x10 8 yr ) the track density from spontaneous fission of 238 U is nearly constant. However, the

  20. New experimental approaches to investigate the fission dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Benlliure, J., E-mail: j.benlliure@usc.es; Rodríguez-Sánchez, J. L.; Alvarez-Pol, H.; Ayyad, Y.; Cortina-Gil, D.; Paradela, C.; Pietras, B.; Ramos, D.; Vargas, J. [Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain); Audouin, L.; Boutoux, G. [Institut de Physique Nucléaire d’Orsay, F-91406 Orsay (France); Bélier, G.; Chatillon, A.; Gorbinet, T.; Laurent, B.; Martin, J.-F.; Pellereau, E.; Taïeb, J. [CEA, DAM, DIF, F-91297 Arpajon (France); Casarejos, E. [Universidad de Vigo, E-36200 Vigo (Spain); Heinz, A. [Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); and others

    2016-07-07

    The first ever achieved full identification of both fission fragments, in atomic and mass number, made it possible to define new observables sensitive to the fission dynamics along the fission path up to the scission point. Moreover, proton-induced fission of {sup 208}Pb at high energies offers optimal conditions for the investigation of dissipative, and transient effects, because of the high-excitation energy of the fissioning nuclei, its low angular momentum, and limited shape distortion by the reaction. In this work we show that the charge distribution of the final fission fragments can constrain the ground-to-saddle dynamics while the mass distribution is sensitive to the dynamics until the scission point.

  1. Burn-up physics in a coupled Hammer-Technion/Cinder-2 system and ENDF/B-V aggregate fission product thermal cross section validation

    International Nuclear Information System (INIS)

    Santos, A. dos.

    1990-01-01

    The new methodology developed in this work has the following purposes: a) to implement a burnup capability into the HAMMER-TECHNION/9/computer code by using the CINDER-2/10/computer code to perform the transmutation analysis for the actinides and fission products; b) to implement a reduced version of the CINDER-2 fission product chain structure to treat explicity nearly 99% of all original CINDER-2 fission product absorption in a typical PWR unit cell; c) to treat the effect of the fission product neutron absorption in an unit cell in a multigroup basis; d) to develop a tentative validation procedure for the ENOF/C-V stable and long-lived fission product nuclear data based on the available experimental data/11-14/. The analysis will be performed by using the reduce chain in the coupled system CINDER-2 to generate the time dependent effective four group cross sections for actinides and fission products and CINDER-2 to perform the complete transmutation analysis with its built-in chain structure. (author)

  2. Minor actinide transmutation in accelerator driven systems

    Energy Technology Data Exchange (ETDEWEB)

    Friess, Friederike [IANUS, TU Darmstadt (Germany)

    2015-07-01

    Transmutation of radioactive waste, the legacy of nuclear energy use, gains rising interest. This includes the development of facilities able to transmute minor actinides (MA) into stable or short-lived isotopes before final disposal. The most common proposal is to use a double-strata approach with accelerator-driven-systems (ADS) for the efficient transmutation of MA and power reactors to dispose plutonium. An ADS consists of a sub-critical core that reaches criticality with neutrons supplied by a spallation target. An MCNP model of the ADS system Multi Purpose Research Reactor for Hightech Applications will be presented. Depletion calculations have been performed for both standard MOX fuel and transmutation fuel with an increased content of minor actinides. The resulting transmutation rates for MAs are compared to published values. Special attention is given to selected fission products such as Tc-99 and I-129, which impact the radiation from the spent fuel significantly.

  3. Fundamental Studies of Irradiation-Induced Defect Formation and Fission Product Dynamics in Oxide Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Stubbins, James

    2012-12-19

    The objective of this research program is to address major nuclear fuels performance issues for the design and use of oxide-type fuels in the current and advanced nuclear reactor applications. Fuel performance is a major issue for extending fuel burn-up which has the added advantage of reducing the used fuel waste stream. It will also be a significant issue with respect to developing advanced fuel cycle processes where it may be possible to incorporate minor actinides in various fuel forms so that they can be 'burned' rather than join the used fuel waste stream. The potential to fission or transmute minor actinides and certain long-lived fission product isotopes would transform the high level waste storage strategy by removing the need to consider fuel storage on the millennium time scale.

  4. 14. International workshop on nuclear fission physics. Proceedings

    International Nuclear Information System (INIS)

    2000-01-01

    The meetings on nuclear fission took place 12-15 October 1998 and was organized by Institute of Physics and Power Engineering. The aim of the workshop was to present and discuss main new both theoretical and experimental results obtained in the area of nuclear fission, dynamical feature, properties of fission fragments and complementary radiation. As usual the program of the workshop was designed to cover a wide range of physical phenomena - from low energy and spontaneous fission to fission of hot rotating nuclei and multifragmentation at intermediate and high energies. Reaction induced by slow and fast neutron, light and heavy ions were discussed [ru

  5. Gastrointestinal absorption of actinides: a review with special reference to primate data

    International Nuclear Information System (INIS)

    Burkart, W.

    1984-01-01

    Large scale geological burial of transuranic wastes from fission power production may expose segments of future generations to trace amounts of actinides in water and food, which, via gastrointestinal absorption, could result in internal doses of alpha radiation. Gastrointestinal absorption of actinide elements is a poorly understood process. Experimental studies, primarily using rodents, often produce ambiguous results with order of magnitude fluctuations in estimates of GI absorption. Since experimental conditions like the chemical form of the fed actinides or reducing and complexing capacity of the stomach content, influence the GI transfer factor in seemingly unpredictable ways, only a better understanding of events at the molecular level will enable more reliable predictions to be made of the organ burdens resulting from actinides passing through the digestive tract. From a review of the existing literature it is apparent that in vitro research data in the area of GI uptake mechanisms (i.e. transport mediated by ion carriers in body fluids and across cell membranes) are virtually non-existant. In view of the uncertainties linked to in vivo uptake experiment, models which approximate man, i.e. derived from non-human primate studies, should be the best choice of experimental systems in which to determine reliable estimates for gastrointestinal transfer factors of actinide elements. (Auth.)

  6. Spontaneous fission of 259Md

    International Nuclear Information System (INIS)

    Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Landrum, J.H.; Dougan, R.J.; Mustafa, M.; Ghiorso, A.; Nitschke, J.M.

    1979-01-01

    The mass and kinetic energy distributions of fission fragments from the spontaneous fission of th newly discovered nuclide 259 Md were obtained. 259 Md was identified as the E. C. daughter of 259 No, and was found to decay entirely (> 95%) by spontaneous fission with a 95-min half-life. From the kinetic energies measured for 397 pairs of coincident fragments, a mass distribution was derived that is symmetric with sigma = 13 amu. 259 Md, together with 258 Fm and 259 Fm, form a select group of three nuclides whose mass division in spontaneous fission is highly symmetric. Unlike the total-kinetic-energy (TKE) distributions of 258 Fm and 259 Fm, which peak at approx. = to 240 MeV, this distribution for 259 Md is broad and is 50 MeV lower in energy. Analysis of the mass and energy distributions shows that events near mass symmetry also exhibit a broad TKE distribution, with one-third of the symmetric events having TKEs less than 200 MeV. The associated of low TKEs with symmetric mass division in the fission of very heavy actinides is anomalous and inconsistent with theories based upon the emergence of fragment shells near the scission point. Either three-body fragmentation or peculiar fragment shapes are assumed as the cause for the large consumption of Coulomb energy observed for a significant fraction of symmetric fissions in 259 Md. 6 figures

  7. FY2011 Annual Report for the Actinide Isomer Detection Project

    International Nuclear Information System (INIS)

    Warren, Glen A.; Francy, Christopher J.; Ressler, Jennifer J.; Erikson, Luke E.; Tatishvili, Gocha; Hatarik, R.

    2011-01-01

    This project seeks to identify a new signature for actinide element detection in active interrogation. This technique works by exciting and identifying long-lived nuclear excited states (isomers) in the actinide isotopes and/or primary fission products. Observation of isomers in the fission products will provide a signature for fissile material. For the actinide isomers, the decay time and energy of the isomeric state is unique to a particular isotope, providing an unambiguous signature for SNM. This project entails isomer identification and characterization and neutron population studies. This document summarizes activities from its third year - completion of the isomer identification characterization experiments and initialization of the neutron population experiments. The population and decay of the isomeric state in 235U remain elusive, although a number of candidate gamma rays have been identified. In the course of the experiments, a number of fission fragment isomers were populated and measured (Ressler 2010). The decays from these isomers may also provide a suitable signature for the presence of fissile material. Several measurements were conducted throughout this project. This report focuses on the results of an experiment conducted collaboratively by PNNL, LLNL and LBNL in December 2010 at LBNL. The measurement involved measuring the gamma-rays emitted from an HEU target when bombarded with 11 MeV neutrons. This report discussed the analysis and resulting conclusions from those measurements. There was one strong candidate, at 1204 keV, of an isomeric signature of 235U. The half-life of the state is estimated to be 9.3 μs. The measured time dependence fits the decay time structure very well. Other possible explanations for the 1204-keV state were investigated, but they could not explain the gamma ray. Unfortunately, the relatively limited statistics of the measurement limit, and the lack of understanding of some of the systematic of the experiment, limit

  8. Mass distributions in nucleon-induced fission at intermediate energies

    CERN Document Server

    Duijvestijn, M C; Hambsch, F J

    2001-01-01

    Temperature-dependent fission barriers and fission-fragment mass distributions are calculated in the framework of the multimodal random neck-rupture model (MM-RNRM). It is shown how the distinction between the different fission modes disappears at higher excitation energies, due to the melting of shell effects. The fission-fragment mass yield calculations are coupled to the nuclear reaction code ALICE-91, which takes into account the competition between the other reaction channels and fission. With the combination of the temperature-dependent MM-RNRM and ALICE-91 nucleon-induced fission is investigated at energies between 10 and 200 MeV for nuclei varying from Au to Am. (72 refs).

  9. Anomalies in the Charge Yields of Fission Fragments from the ^{238}U(n,f) Reaction.

    Science.gov (United States)

    Wilson, J N; Lebois, M; Qi, L; Amador-Celdran, P; Bleuel, D; Briz, J A; Carroll, R; Catford, W; De Witte, H; Doherty, D T; Eloirdi, R; Georgiev, G; Gottardo, A; Goasduff, A; Hadyńska-Klęk, K; Hauschild, K; Hess, H; Ingeberg, V; Konstantinopoulos, T; Ljungvall, J; Lopez-Martens, A; Lorusso, G; Lozeva, R; Lutter, R; Marini, P; Matea, I; Materna, T; Mathieu, L; Oberstedt, A; Oberstedt, S; Panebianco, S; Podolyák, Zs; Porta, A; Regan, P H; Reiter, P; Rezynkina, K; Rose, S J; Sahin, E; Seidlitz, M; Serot, O; Shearman, R; Siebeck, B; Siem, S; Smith, A G; Tveten, G M; Verney, D; Warr, N; Zeiser, F; Zielinska, M

    2017-06-02

    Fast-neutron-induced fission of ^{238}U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency γ-ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via γ-γ coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.

  10. Fusability and survivability in reactions leading to heavy nuclei in the vicinity of the N = 126 shell

    International Nuclear Information System (INIS)

    Sagajdak, R.N.

    2008-01-01

    The production of heavy nuclei from Rn to Th around the N = 126 neutron shell in complete fusion reactions of nuclei has been considered in a systematic way in the framework of the conventional barrier-passing fusion model coupled with the Standard Statistical Model (SSM). Available data on the excitation functions for fusion and production of evaporation residues obtained in very asymmetric combinations are described with these models rather well. In the interaction of massive projectiles with heavy target nuclei quasi-fission effects appear in the entrance reaction channel. The quantity of the fusion probability introduced empirically has been used to reproduce excitation functions with the same SSM parameters (fission barriers) as those obtained in the analysis of very asymmetric combinations. A lack of stabilization against fission around N = 126 for Th nuclei was earlier explained with a reduced collective contribution to the level density in spherical nuclei. However, the present analysis shows severe inhibition for fusion, i.e., the drop in production cross sections of Th nuclei in the vicinity of N = 126 is mainly caused by entrance channel effects. The macroscopic component of fission barriers for nuclei involved in a deexcitation cascade has been derived and compared with the theoretical model predictions and available data

  11. Systematic studies of the energy levels of odd z even mass actinides

    International Nuclear Information System (INIS)

    Sood, P.C.

    1985-01-01

    The bandhead energies for the two-particle states in doubly odd actinides are evaluated based on the calculation of the zero-range residual interaction energy contribution. Guidelines are presented to decide the relative ordering of the expected configurations, leading to spin-parity assignments to the ground states and to the isomeric states in these nuclei. Presently available experimental information lists definite spin-parity for only four out of over fifty known nuclides in the region. Expected location of several new isomers, particularly in heavier nuclei, is indicated

  12. The measurement of prompt neutron spectrum in spontaneous fission of {sup 244}Cm

    Energy Technology Data Exchange (ETDEWEB)

    Batenkov, O.I.; Boykov, G.S.; Drapchinsky, L.V.; Majorov, M.Ju.; Trenkin, V.A. [V.G. Khlopin Radium Inst., Saint Petersburg (Russian Federation)

    1997-03-01

    Under the Program of Measurements of Prompt Fission Neutron Spectra of Minor Actinides for Transmutation Purposes the integral neutron spectrum in spontaneous fission of {sup 244}Cm has been measured by the time-of-flight method in the energy range of 0.1-15 MeV relative to the standard neutron spectrum in {sup 252}Cf spontaneous fission. Essential attention was paid to revealing of possible systematic errors. It is shown, that the {sup 244}Cm spectrum shape may be well described by using Mannhart evaluation with appropriate parameter of Maxwell temperature T{sub M} = 1.37 MeV. (author)

  13. Significance of actinide chemistry for the long-term safety of waste disposal

    International Nuclear Information System (INIS)

    Kim, Jae Il

    2006-01-01

    A geochemical approach to the long-term safety of waste disposal is discussed in connection with the significance of actinides, which shall deliver the major radioactivity inventory subsequent to the relatively short-term decay of fission products. Every power reactor generates transuranic (TRU) elements: plutonium and minor actinides (Np, Am, Cm), which consist chiefly of long-lived nuclides emitting alpha radiation. The amount of TRU actinides generated in a fuel life period is found to be relatively small (about 1 wt% or less in spent fuel) but their radioactivity persists many hundred thousands years. Geological confinement of waste containing TRU actinides demands, as a result, fundamental knowledge on the geochemical behavior of actinides in the repository environment for a long period of time. Appraisal of the scientific progress in this subject area is the main objective of the present paper. Following the introductory discussion on natural radioactivities, the nuclear fuel cycle is briefly brought up with reference to actinide generation and waste disposal. As the long-term disposal safety concerns inevitably with actinides, the significance of the aquatic actinide chemistry is summarized in two parts: the fundamental properties relevant to their aquatic behavior and the geochemical reactions in nanoscopic scale. The constrained space of writing allows discussion on some examples only, for which topics of the primary concern are selected, e.g. apparent solubility and colloid generation, colloid-facilitated migration, notable speciation of such processes, etc. Discussion is summed up to end with how to make a geochemical approach available for the long-term disposal safety of nuclear waste or for the Performance Assessment (PA) as known generally

  14. The effect of actinides on the microstructural development in a metallic high-level nuclear waste form

    Energy Technology Data Exchange (ETDEWEB)

    Keiser, D. D., Jr.; Sinkler, W.; Abraham, D. P.; Richardson, J. W., Jr.; McDeavitt, S. M.

    1999-10-25

    Waste forms to contain material residual from an electrometallurgical treatment of spent nuclear fuel have been developed by Argonne National Laboratory. One of these waste forms contains waste stainless steel (SS), fission products that are noble to the process (e.g., Tc, Ru, Pd, Rh), Zr, and actinides. The baseline composition of this metallic waste form is SS-15wt.% Zr. The metallurgy of this baseline alloy has been well characterized. On the other hand, the effects of actinides on the alloy microstructure are not well understood. As a result, SS-Zr alloys with added U, Pu, and/or Np have been cast and then characterized, using scanning electron microscopy, transmission electron microscopy, and neutron diffraction, to investigate the microstructural development in SS-Zr alloys that contain actinides. Actinides were found to congregate non-uniformally in a Zr(Fe,Cr,Ni){sub 2+x} phase. Apparently, the actinides were contained in varying amounts in the different polytypes (C14, C15, and C36) of the Zr(Fe,Cr,Ni){sub 2+x} phase. Heat treatment of an actinide-containing SS-15 wt.% Zr alloy showed the observed microstructure to be stable.

  15. Influence of mass-asymmetry and ground state spin on fission fragment angular distributions

    International Nuclear Information System (INIS)

    Thomas, R.G.; Biswas, D.C.; Saxena, A.; Pant, L.M.; Nayak, B.K.; Vind, R.P.; Sahu, P.K.; Sinha, Shrabani; Choudhury, R.K.

    2001-01-01

    The strong influence of the target or/and projectile ground state spin on the anomalously large anisotropies of fission fragments produced in the heavy-ion induced fission of actinide targets were reported earlier. Interestingly, all those systems studied were having a mass asymmetry greater than the Businaro-Gallone critical asymmetry and hence the presence of pre-equilibrium fission was unambiguously ruled out. The observed anisotropies were successfully explained using the ECD-K-States model. It is of interest to know the influence of the target/projectile ground state spin on systems having an entrance channel mass asymmetry less than the critical value where pre-equilibrium fission cannot be ignored. With this motivation we performed measurements of fission fragment angular distributions of the 16 O+ 235 U (spin=7/2) system

  16. Minor Actinide Burning in Thermal Reactors. A Report by the Working Party on Scientific Issues of Reactor Systems

    International Nuclear Information System (INIS)

    Hesketh, K.; Porsch, D.; Rimpault, G.; Taiwo, T.; Worrall, A.

    2013-01-01

    The actinides (or actinoids) are those elements in the periodic table from actinium upwards. Uranium (U) and plutonium (Pu) are two of the principal elements in nuclear fuel that could be classed as major actinides. The minor actinides are normally taken to be the triad of neptunium (Np), americium (Am) and curium (Cm). The combined masses of the remaining actinides (i.e. actinium, thorium, protactinium, berkelium, californium, einsteinium and fermium) are small enough to be regarded as very minor trace contaminants in nuclear fuel. Those elements above uranium in the periodic table are known collectively as the transuranics (TRUs). The operation of a nuclear reactor produces large quantities of irradiated fuel (sometimes referred to as spent fuel), which is either stored prior to eventual deep geological disposal or reprocessed to enable actinide recycling. A modern light water reactor (LWR) of 1 GWe capacity will typically discharge about 20-25 tonnes of irradiated fuel per year of operation. About 93-94% of the mass of uranium oxide irradiated fuel is comprised of uranium (mostly 238 U), with about 4-5% fission products and ∼1% plutonium. About 0.1-0.2% of the mass is comprised of neptunium, americium and curium. These latter elements accumulate in nuclear fuel because of neutron captures, and they contribute significantly to decay heat loading and neutron output, as well as to the overall radio-toxic hazard of spent fuel. Although the total minor actinide mass is relatively small - approximately 20-25 kg per year from a 1 GWe LWR - it has a disproportionate impact on spent fuel disposal, and thus the longstanding interest in transmuting these actinides either by fission (to fission products) or neutron capture in order to reduce their impact on the back end of the fuel cycle. The combined masses of the trace actinides actinium, thorium, protactinium, berkelium and californium in irradiated LWR fuel are only about 2 parts per billion, which is far too low for

  17. Immobilization of fission products arising from pyrometallurgical reprocessing in chloride media

    Science.gov (United States)

    Leturcq, G.; Grandjean, A.; Rigaud, D.; Perouty, P.; Charlot, M.

    2005-12-01

    Spent nuclear fuel reprocessing to recover energy-producing elements such as uranium or plutonium can be performed by a pyrochemical process. In such method, the actinides and fission products are extracted by electrodeposition in a molten chloride medium. These processes generate chlorinated alkali salt flows contaminated by fission products, mainly Cs, Ba, Sr and rare earth elements constituting high-level waste. Two possible alternatives are investigated for managing this wasteform; a protocol is described for dechlorinating the fission products to allow vitrification, and mineral phases capable of immobilizing chlorides are listed to allow specification of a dedicated ceramic matrix suitable for containment of these chlorinated waste streams. The results of tests to synthesize chlorosilicate phases are also discussed.

  18. Development of fission micro-chambers for nuclear waste incineration studies

    CERN Document Server

    Fadil, M; Christophe, S; Deruelle, O; Fioni, G; Marie, F; Mounier, C; Ridikas, D; Trapp, J P

    2002-01-01

    The Incineration by Accelerator (INCA) project of the Directorate for Science of Matter of the French Atomic Energy Authority (CEA/DSM) aims to outline the ideal physical conditions to transmute minor actinides in a high intensity neutron flux obtained either by hybrid systems or innovative critical reactors. To measure on-line the incineration rates of minor actinides, we are developing an innovative Double Deposit Fission Chamber (DDFC) working in current mode. Our method is based on a comparison between the isotope under study and a reference material whose nuclear parameters are well known, as sup 2 sup 3 sup 5 U and sup 2 sup 3 sup 9 Pu. This new fission chamber will be used in the High Flux Reactor in Grenoble/France in a neutron flux of 1.2x10 sup 1 sup 5 n cm sup - sup 2 s sup - sup 1 for 50 days, the operating cycle of the reactor. These specific experimental conditions require substantial modifications of the existing chambers. The first experiment will be carried out in fall 2000.

  19. Structure of Warm Nuclei

    International Nuclear Information System (INIS)

    Aaberg, S.; Uhrenholt, H.

    2009-01-01

    We study the structure of nuclei in the energy region between the ground state and the neutron separation energy, here called warm nuclei. The onset of chaos in the nucleus as excitation energy is increased is briefly reviewed. Chaos implies fluctuations of energies and wave functions qualitatively the same for all chaotic nuclei. On the other hand, large structure effects are seen, e.g. in the level-density function at same excitation energies. A microscopic model for the level density is reviewed and we discuss effects on structure of the total level-density function, parity enhancement, and the spin distribution function. Comparisons to data are performed at the neutron separation energy for all observed nuclei, and structure of the level-density function for a few measured cases. The role of structure effects in the level-density function for fission dynamics is exemplified.

  20. Kr and Xe isotopes from spontaneous fission of 248Cm and 250Cf

    International Nuclear Information System (INIS)

    Srinivasan, B.

    1980-01-01

    Relative yields of Kr and Xe isotopes from the spontaneous fission of 248 Cm and 250 Cf have been determined mass spectrometrically. The yields are as follows: 83 Kr/ 84 Kr/ 85 Kr/ 86 Kr = 0.223/0.458/0.596/ identical 1.00 and 0.306/0.582/0.793/ identical 1.00; 131 Xe/ 134 Xe/ 136 Xe = 0.486/0.819/1.075 identical 1.00 and 0.343/0.506/0.851/ identical 1.00 from 248 Cm and 250 Cf, respectively. The Xe yields from 248 Cm agree with an earlier determination by Leich et al. Neither of these yield patterns matches that of fissiogenic Kr and Xe in carbonaceous chondrites and hence 248 Cm and 250 Cf are ruled out as progenitors of the meteoritic Kr and Xe. In general, none of the spontaneously fissioning nuclides of actinide elements can be identified as a possible progenitor. Even the mixtures of actinides, including a combination of 248 Cm and 250 Cm, are unsuitable. The origin of anomalous Kr and Xe in carbonaceous chondrites must then be traced either to the spontaneous fission of a superheavy element or to peculiarities in specific nucleosynthetic reactions. (orig.)

  1. On the description of the (HI, xn) reaction excitation functions for the case of weakly fissioning compound nuclei

    International Nuclear Information System (INIS)

    Kamanin, V.V.; Karamyan, S.A.

    1980-01-01

    A possibility to obtain parameters of nuclear temperature and critical angular momentum for the compound nucleus production on the base of the (HI, xn) reaction excitation function description are considered for the case of weakly fissioning nuclei. Experimental data on 152 Sm( 12 C, 2n) 162 Er, 148 Nd( 16 O, 3n) 161 Er, sup(150)Nd(sup(16)O, 3-5n)sup(163-161)Er, sup(148)Nd(sup(18)O, 4-5n)sup(162,161)Er, sup(118)Sn(sup(40)Ar, 5-6n)sup(153,152)Er and sup(74)Ge(sup(84)Kr, 5-6n)sup(153,152)Er reactions are discussed. The formulae, taking into accout the distribution of compound nuclei in angular momentum and competition between channels of the neutron and γ-ray emission, are given. The formulae are applied for the description of the excitation functions, characterized by a good accuracy of the particle energy measuring. A satisfactory accordance between the calculation and experiment is achieved. The conclusion on sensitivity of the nuclear temperature values to exact evaluation of competition between the neutron and γ-ray emission channels is drawn

  2. New isomeric states in 152,154,156Nd produced by spontaneous fission of 252Cf

    International Nuclear Information System (INIS)

    Gautherin, C.; Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Phan, X.H.; Theisen, C.; Belier, G.; Girod, M.; Meot, V.; Peru, S.; Astier, A.; Ducroux, L.; Meyer, M.; Redon, N.

    1998-01-01

    Isomeric states have been observed in fission-fragments produced by spontaneous fission of 252 Cf. These states are found in neutron rich nuclei of different structure and deformations. About 50 isomeric nuclei have been observed using coincidences between γ-rays identified in EUROGAM II and fission fragments detected in photovoltaic cells (SAPhIR). Lifetimes in the range from 20 ns to 2μs have been measured. Presented calculations based on HFB+D1S force on new measured isomeric states in the 152,154,156 Nd show evidence for K-isomers. (orig.)

  3. Fission yields data generation and benchmarks of decay heat estimation of a nuclear fuel

    Science.gov (United States)

    Gil, Choong-Sup; Kim, Do Heon; Yoo, Jae Kwon; Lee, Jounghwa

    2017-09-01

    Fission yields data with the ENDF-6 format of 235U, 239Pu, and several actinides dependent on incident neutron energies have been generated using the GEF code. In addition, fission yields data libraries of ORIGEN-S, -ARP modules in the SCALE code, have been generated with the new data. The decay heats by ORIGEN-S using the new fission yields data have been calculated and compared with the measured data for validation in this study. The fission yields data ORIGEN-S libraries based on ENDF/B-VII.1, JEFF-3.1.1, and JENDL/FPY-2011 have also been generated, and decay heats were calculated using the ORIGEN-S libraries for analyses and comparisons.

  4. Calculated leaching of certain fission products from a cylinder of French glass

    International Nuclear Information System (INIS)

    Blomqvist, G.

    1977-07-01

    The probable total leaching of the most important fission products and actinides have been tabulated for a cylinder of French HLW glass with approximately 9 percent fission products. The calculations cover the period between 30 and 10000 years after removal from the reactor. The cylinder is of the type planned for the introduction of the HLW into Swedish crystalline rocks. All the components are supposed to have the same leach rate. The calculations also include the probable thickness of eroded glass layer/year. (author)

  5. Fission neutron spectra measurements at LANSCE - Status and plans

    International Nuclear Information System (INIS)

    Haight, R. C.; Noda, S.; Nelson, R. O.; O'Donnell, J. M.; Devlin, M.; Chatillon, A.; Granier, T.; Taiebb, J.; Laurent, B.; Belier, G.; Becker, J. A.; Wu, C. Y.

    2010-01-01

    A program to measure fission neutron spectra from neutron-induced fission of actinides is underway at the Los Alamos Neutron Science Center (LANSCE) in a collaboration among the CEA laboratory at Bruyeres-le-Chatel, Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The spallation source of fast neutrons at LANSCE is used to provide incident neutron energies from less than 1 MeV to 100 MeV or higher. The fission events take place in a gas-ionization fission chamber, and the time of flight from the neutron source to that chamber gives the energy of the incident neutron. Outgoing neutrons are detected by an array of organic liquid scintillator neutron detectors, and their energies are deduced from the time of flight from the fission chamber to the neutron detector. Measurements have been made of the fission neutrons from fission of 235 U, 238 U, 237 Np and 239 Pu. The range of outgoing energies measured so far is from 0.7 MeV to approximately 8 MeV. These partial spectra and average fission neutron energies are compared with evaluated data and with models of fission neutron emission. Results to date are summarized in this presentation. Future plans are to make significant improvements in the fission chambers, neutron detectors, signal processing, data acquisition and the experimental environment to provide high fidelity data including measurements of fission neutrons below 0.7 MeV and improvements in the data above 8 MeV. (authors)

  6. Theory of neutron emission in fission

    International Nuclear Information System (INIS)

    Madland, D.G.

    1989-01-01

    Following a summary of the observables in neutron emission in fission, a brief history is given of theoretical representations of the prompt fission neutron spectrum N(E) and average prompt neutron multiplicity /bar /nu///sub p/. This is followed by descriptions, together with examples, of modern approaches to the calculation of these quantities including recent advancements. Emphasis will be placed upon the predictability and accuracy of the modern approaches. In particular, the dependence of N(E) and /bar /nu///sub p/ on the fissioning nucleus and its excitation energy will be discussed, as will the effects of and competition between first-, second- and third-chance fission in circumstances of high excitation energy. Finally, properties of neutron-rich (fission-fragment) nuclei are discussed that must be better known to calculate N(E) and /bar /nu///sub p/ with higher accuracy than is currently possible. 17 refs., 11 figs

  7. Use of fast reactors for actinide transmutation. Proceedings of a specialists meeting held in Obninsk, Russian Federation, 22-24 September 1992

    Energy Technology Data Exchange (ETDEWEB)

    1993-03-15

    The management of radioactive waste is one of the key issues in today`s discussions on nuclear energy, especially the long term disposal of high level radioactive wastes. The recycling of plutonium in liquid metal fast breeder reactors (LMFBRs) would allow `burning` of the associated extremely long life transuranic waste, particularly actinides, thus reducing the required isolation time for high level waste from tens of thousands of years to hundreds of years for fission products only. The International Working Group on Fast Reactors (IWGFR) decided to include the topic of actinide transmutation in liquid metal fast breeder reactors in its programme. The IAEA organized the Specialists Meeting on Use of Fast Breeder Reactors for Actinide Transmutation in Obninsk, Russian Federation, from 22 to 24 September 1992. The specialists agree that future progress in solving transmutation problems could be achieved by improvements in: Radiochemical partitioning and extraction of the actinides from the spent fuel (at least 98% for Np and Cm and 99.9% for Pu and Am isotopes); technological research and development on the design, fabrication and irradiation of the minor actinides (MAs) containing fuels; nuclear constants measurement and evaluation (selective cross-sections, fission fragments yields, delayed neutron parameters) especially for MA burners; demonstration of the feasibility of the safe and economic MA burner cores; knowledge of the impact of maximum tolerable amount of rare earths in americium containing fuels. Refs, figs and tabs.

  8. Safe management of actinides in the nuclear fuel cycle: Role of mineralogy

    International Nuclear Information System (INIS)

    Ewing, R.C.

    2011-01-01

    During the past 60 years, more than 1800 metric tonnes of Pu, and substantial quantities of the 'minor' actinides, such as Np, Am and Cm, have been generated in nuclear reactors. Some of these transuranium elements can be a source of energy in fission reactions (e.g., 239 Pu), a source of fissile material for nuclear weapons (e.g., 239 Pu and 237 Np), and of environmental concern because of their long-half lives and radiotoxicity (e.g., 239 Pu and 237 Np). There are two basic strategies for the disposition of these heavy elements: (1) to 'burn' or transmute the actinides using nuclear reactors or accelerators; (2) to 'sequester' the actinides in chemically durable, radiation-resistant materials that are suitable for geologic disposal. There has been substantial interest in the use of actinide-bearing minerals, especially isometric pyrochlore, A 2 B 2 O 7 (A rare earths; B = Ti, Zr, Sn, Hf), for the immobilization of actinides, particularly plutonium, both as inert matrix fuels and nuclear waste forms. Systematic studies of rare-earth pyrochlores have led to the discovery that certain compositions (B = Zr, Hf) are stable to very high doses of alpha-decay event damage. Recent developments in our understanding of the properties of heavy element solids have opened up new possibilities for the design of advanced nuclear fuels and waste forms. (author)

  9. A new fission-fragment detector to complement the CACTUS-SiRi setup at the Oslo Cyclotron Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Tornyi, T.G., E-mail: tornyitom@atomki.hu [Department of Physics, University of Oslo (Norway); Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen (Hungary); Görgen, A.; Guttormsen, M.; Larsen, A.C.; Siem, S. [Department of Physics, University of Oslo (Norway); Krasznahorkay, A. [Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen (Hungary); Csige, L. [Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen (Hungary); Max-Planck-Institute for Quantum Optics, D-85748 Garching (Germany)

    2014-02-21

    An array of Parallel Plate Avalanche Counters (PPAC) for the detection of heavy ions has been developed. The new device, NIFF (Nuclear Instrument for Fission Fragments), consists of four individual detectors and covers 60% of 2π. It was designed to be used in conjunction with the SiRi array of ΔE−E silicon telescopes for light charged particles and fits into the CACTUS array of 28 large-volume NaI scintillation detectors at the Oslo Cyclotron Laboratory. The low-pressure gas-filled PPACs are sensitive for the detection of fission fragments, but are insensitive to scattered beam particles of light ions or light-ion ejectiles. The PPAC detectors of NIFF have good time resolution and can be used either to select or to veto fission events in in-beam experiments with light-ion beams and actinide targets. The powerful combination of SiRi, CACTUS, and NIFF provides new research opportunities for the study of nuclear structure and nuclear reactions in the actinide region. The new setup is particularly well suited to study the competition of fission and γ decay as a function of excitation energy.

  10. Consultants’ Meeting on Recommended Input Parameters for Fission Cross-Section Calculations. Summary Report

    International Nuclear Information System (INIS)

    Capote Noy, Roberto; Simakov, Stanislav; Goriely, Stephane; Hilaire, Stephane; Iwamoto, Osamu; Kawano, Toshihiko; Koning, Arjan

    2014-12-01

    A Consultants’ Meeting on “Recommended Input Parameters for Fission Cross-Section Calculations” was held at IAEA Headquarters, Vienna, Austria to define the scope, deliverables and appropriate work programme of a possible Coordinated Research Project (CRP) on the subject. Presentations are available online at https://www-nds.iaea.org/indexmeeting-crp/CM-RIPL-fission/. A new CRP was endorsed to recommend a comprehensive set of fission input parameters needed for the modelling of fission cross sections. Special attention will be given to the modelling of photon and nucleon induced reactions on actinides with emphasis on incident energies below 30 MeV. The goals and detailed deliverables of the planned CRP were proposed. A Hauser-Feshbach code intercomparison was recommended. (author)

  11. Realistic fission models, new beta-decay half-lives and the r-process in neutron star mergers

    International Nuclear Information System (INIS)

    Shibagaki, S.; Kajino, T.; Chiba, S.; Lorusso, G.; Nishimura, S.; Mathews, G. J.

    2014-01-01

    Almost half of heavy nuclei beyond iron are considered to be produced by rapid neutron capture process (r-process). This process occurs in the neutron-rich environment such as core-collapse supernovae or neutron star mergers, but the main production site is still unknown. In the r-process of neutron star mergers, nuclear fission reactions play an important role. Also beta-decay half-lives of magic nuclei are crucial for the r-process. We have carried out r-process nucleosynthesis calculations based upon new theoretical estimates of fission fragment distributions and new beta-decay half-lives for N=82 nuclei measured at RIBF-RIKEN. We investigate the effect of nuclear fission on abundance patterns in the matter ejected from neutron star mergers with two different fission fragment mass distributions. We also discuss how the new experimental beta-decay half-lives affect the r-process

  12. SAPhIR: a fission-fragment detector

    International Nuclear Information System (INIS)

    Theisen, Ch.; Gautherin, C.; Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Barreau, G.; Doan, T. P.; Belier, G.; Meot, V.; Ethvignot, Th.; Cahan, B.; Le Coguie, A.; Coppolani, X.; Delaitre, B.; Le Bourlout, P.; Legou, Ph.; Maillard, O.; Durand, G.; Bouillac, A.

    1998-01-01

    SAPhIR is the acronym for S a clay A q uitaine P ho tovoltaic cells for I s omer R e search. It consists of solar cells, used for fission-fragment detection. It is a collaboration between 3 laboratories: CEA Saclay, CENBG Bordeaux and CEA Bruyeres le Chatel. The coupling of a highly efficient fission-fragment detector like SAPhIR with EUROBALL will provide new insights in the study of very deformed nuclear matter and in the spectroscopy of neutron-rich nuclei

  13. Actinide burning in the integral fast reactor

    International Nuclear Information System (INIS)

    Chang, Y.I.

    1993-01-01

    During the past few years, Argonne National Laboratory has been developing the integral fast reactor (IFR), an advanced liquid-metal reactor concept. In the IFR, the inherent properties of liquid-metal cooling are combined with a new metallic fuel and a radically different refining process to allow breakthroughs in passive safety, fuel cycle economics, and waste management. A key feature of the IFR concept is its unique pyroprocessing. Pyroprocessing has the potential to radically improve long-term waste management strategies by exploiting the following attributes: 1. Minor actinides accompany plutonium product stream; therefore, actinide recycling occurs naturally. Actinides, the primary source of long-term radiological toxicity, are removed from the waste stream and returned to the reactor for in situ burning, generating useful energy. 2. High-level waste volume from pyroprocessing call be reduced substantially as compared with direct disposal of spent fuel. 3. Decay heat loading in the repository can be reduced by a large factor, especially for the long-term burden. 4. Low-level waste generation is minimal. 5. Troublesome fission products, such as 99 Tc, 129 I, and 14 C, are contained and immobilized. Singly or in combination, the foregoing attributes provide important improvements in long-term waste management in terms of the ease in meeting technical performance requirements (perhaps even the feasibility of demonstrating that technical performance requirements can be met) and perhaps also in ultimate public acceptance. Actinide recycling, if successfully developed, could well help the current repository program by providing an opportunity to enhance capacity utilization and by deferring the need for future repositories. It also represents a viable technical backup option in the event unforeseen difficulties arise in the repository licensing process

  14. Detection of fission fragments using thick samples in contact with solid state nuclear track detectors

    International Nuclear Information System (INIS)

    Lima, D.A. de; Martins, J.B.; Tavares, O.A.P.

    1987-01-01

    Whenever use is made of thick samples in contact with solid state nuclear track detectors for determining fission yields, one of the fundamental problems is the evaluation of the effective number of target nuclei which contributes to the fraction of the number of fission events that will be recorded. The evaluation of the effective number of target nuclei which contributes to recorded events is based on the effective thickness of the sample. A method for evaluating effective thickness of thick samples for binary fission modes, is presented. A cross section equation which takes into account all the necessary corrections due to fragment attenuation effects by a thick target for calculation induced fission yields, was obtained. (Author) [pt

  15. Hyperfission - a new mode of nuclear fission

    International Nuclear Information System (INIS)

    Ion, D.B.; Ivascu, M.; Ion-Mihai, R.

    1988-02-01

    In this paper the nuclear hyperfission as a new mode of fission, possible for heavy elements with Z > 92, is investigated. The Q-systematics, hyperfissibility parameters, hyperfission barrier as well as the essential hindrance factors are presented. The hyperfission hindrance factor relative to that of fission is found to be in the interval 1.0x10 -17 - 3.4x10 -16 for the parent nuclei with Z = 92-108. (orig.)

  16. Method for the recovery of actinide elements from nuclear reactor waste

    International Nuclear Information System (INIS)

    Horwitz, E.P.; Delphin, W.H.; Mason, G.W.

    1979-01-01

    A process is described for partitioning and recovering actinide values from acidic waste solutions resulting from reprocessing of irradiated nuclear fuels by adding hydroxylammonium nitrate and hydrazine to the waste solution to adjust the valence of the neptunium and plutonium values in the solution to the +4 oxidation state, thus forming a feed solution and contacting the feed solution with an extractant of dihexoxyethyl phosphoric acid in an organic diluent whereby the actinide values, most of the rare earth values and some fission product values are taken up by the extractant. Separation is achieved by contacting the loaded extractant with two aqueous strip solutions, a nitric acid solution to selectively strip the americium, curium and rare earth values and an oxalate and oxalic acid or trimethylammonium hydrogen oxalate to selectively strip the neptunium, plutonium and fission product values. Uranium values remain in the extractant and may be recovered with a phosphoric acid strip. The neptunium and plutonium values are recovered from the oxalate by adding sufficient nitric acid to destroy the complexing ability of the oxalate, forming a second feed, and contacting the second feed with a second extractant of tricaprylmethylammonium nitrate in an inert diluent whereby the neptunium and plutonium values are selectively extracted. The values are recovered from the extractant with formic acid

  17. Neutron-induced Fission Cross Sections of Am and Cm isotopes (Final Report of Research Contract 14485). Resonance and Fast Neutron Induced Fission Cross Sections of Americium and Curium Nuclides (Third-year Progress Report of Research Contract 14485)

    International Nuclear Information System (INIS)

    Alekseev, A.A.; Bergman, A.A.; Berlev, A.I.; Koptelov, E.A.; Egorov, A.S.; Samylin, B.F.; Trufanov, A.M.; Fursov, B.I.; Shorin, V.S.

    2012-01-01

    The neutron induced fission cross sections of Am and Cm isotopes were measured relative to 239 Pu in the neutron energy range from 1 eV to 20 keV at the INR RAS lead slowing down spectrometer LSDS-100. The fission resonance integrals were also estimated using the measured cross section data. The results have been compared with the available experimental and evaluated data. This analysis has shown the present status of the measured fission cross sections and the necessity to revise the evaluated cross sections libraries for the minor actinides. (author)

  18. Recycle of LWR actinides to an IFR

    International Nuclear Information System (INIS)

    Pierce, R.D.; Ackerman, J.P.; Johnson, G.K.; Mulcahey, T.P.; Poa, D.S.

    1991-01-01

    Large quantities of actinide elements are present in irradiated light water reactor fuel that is stored throughout the world. Because of the high fission to capture ratio for the transuranium (TRU) elements with the high energy neutrons in metal-fueled integral fast reactors (IFR), that reactor can consume these elements effectively. The stored fuel may represent valuable resource for the expanding application of fast power reactors. In addition, the removal of TRU elements from spent LWR fuel has the potential for increasing the capacity of high level waste facilities by reducing the heat load and may increase the margin of safety in meeting licensing requirement. Argonne National Laboratory is developing a pyrochemical process, which is compatible with the IFR fuel cycle for the recovery of TRU elements from LWR fuel. The proposed product is a metallic actinide ingot, which can be introduced into the electrorefining step of the IFR process. Two pyrochemical processes, that is, salt transport process and blanket processing study, are discussed in this paper. Also the experimental studies are reported. (K.I.)

  19. The Prompt Fission Neutron Spectrum of 235U for Einc 0.7-5.0 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Jaime A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devlin, Matthew James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haight, Robert Cameron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); O' Donnell, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lee, Hye Young [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mosby, Shea Morgan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Taddeucci, Terry Nicholas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kelly, Keegan John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fotiadis, Nikolaos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Neudecker, Denise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); White, Morgan Curtis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Talou, Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Solomon, Clell Jeffrey Jr. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wu, Ching-Yen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bucher, Brian Michael [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Buckner, Matthew Quinn [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Henderson, Roger Alan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-03-23

    The Chi-Nu experiment aims to accurately measure the prompt fission neutron spectrum (PFNS) for the major actinides. At the Los Alamos Neutron Science Center (LANSCE), fission can be induced using the white neutron source. Using a two arm time of flight (T.O.F) technique; Chi-Nu presents a preliminary result of the low energy component of the 235U PFNS measured using an array of 22-Lithium glass scintillators.

  20. Safe management of actinides in the nuclear fuel cycle: Role of mineralogy; La gestion des actinides dans le cycle du combustible nucleaire: le role de la mineralogie

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R.C. [Department of Nuclear Engineering and Radiological Sciences, Department of Geological Sciences, Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States)

    2011-02-15

    During the past 60 years, more than 1800 metric tonnes of Pu, and substantial quantities of the 'minor' actinides, such as Np, Am and Cm, have been generated in nuclear reactors. Some of these transuranium elements can be a source of energy in fission reactions (e.g., {sup 239}Pu), a source of fissile material for nuclear weapons (e.g., {sup 239}Pu and {sup 237}Np), and of environmental concern because of their long-half lives and radiotoxicity (e.g., {sup 239}Pu and {sup 237}Np). There are two basic strategies for the disposition of these heavy elements: (1) to 'burn' or transmute the actinides using nuclear reactors or accelerators; (2) to 'sequester' the actinides in chemically durable, radiation-resistant materials that are suitable for geologic disposal. There has been substantial interest in the use of actinide-bearing minerals, especially isometric pyrochlore, A{sub 2}B{sub 2}O{sub 7} (A rare earths; B = Ti, Zr, Sn, Hf), for the immobilization of actinides, particularly plutonium, both as inert matrix fuels and nuclear waste forms. Systematic studies of rare-earth pyrochlores have led to the discovery that certain compositions (B = Zr, Hf) are stable to very high doses of alpha-decay event damage. Recent developments in our understanding of the properties of heavy element solids have opened up new possibilities for the design of advanced nuclear fuels and waste forms. (author)

  1. On the fission probability for 235U, 239Pu and 241Pu

    International Nuclear Information System (INIS)

    Benzi, V.; Maino, G.; Menapace, E.

    1978-01-01

    An evaluation of the GAMMAsub(n)/GAMMAsub(f) ratio for the 236 U, 240 Pu and 242 Pu compound nuclei is carried out. First chance and second chance fission cross sections are estimated from the ''evaporation'' model; particularly, a largely increasing trend was found for the first chance fission cross section above the (n,n'f) process threshold. The GAMMAsub(n)/GAMMAsub(f) ratios for the analyzed nuclei show a bump-like structure, that seems to be in agreement with the theoretical predictions reported in literature

  2. Neutron-Induced Fission Cross Section of Uranium, Americium and Curium Isotopes. Progress report - Research Contract 14485, Coordinated Research Project on Minor Actinide Neutron Reaction Data (MANREAD)

    International Nuclear Information System (INIS)

    Alekseev, A.A.; Bergman, A.A.; Berlev, A.I.; Koptelov, E.A.; Samylin, B.F.; Trufanov, A.M.; Fursov, B.I.; Shorin, V.S.

    2009-12-01

    This report contains brief description of the Lead Slowing Down Spectrometer and results of measurements of neutron-induced fission cross sections for 236 U, 242m Am, 243 Cm, 244 Cm, 245 Cm and 246 Cm done at this spectrometer. The work was partially supported through the IAEA research contract RC-14485-RD in the framework of the IAEA Coordinated Research Project 'Minor Actinide Neutron Reaction Data (MANREAD)'. The detailed description of the experimental set up, measurements procedure and data treatment can be found in the JIA-1182 (2007) and JIA-1212 (2009) reports from the Institute of Nuclear Research of the Russian Academy of Science published in Russian. Part 1 contains the first year report of the research contract and part 2 the second year report. (author)

  3. Thorium-uranium fission radiography

    Science.gov (United States)

    Haines, E. L.; Weiss, J. R.; Burnett, D. S.; Woolum, D. S.

    1976-01-01

    Results are described for studies designed to develop routine methods for in-situ measurement of the abundance of Th and U on a microscale in heterogeneous samples, especially rocks, using the secondary high-energy neutron flux developed when the 650 MeV proton beam of an accelerator is stopped in a 42 x 42 cm diam Cu cylinder. Irradiations were performed at three different locations in a rabbit tube in the beam stop area, and thick metal foils of Bi, Th, and natural U as well as polished silicate glasses of known U and Th contents were used as targets and were placed in contact with mica which served as a fission track detector. In many cases both bare and Cd-covered detectors were exposed. The exposed mica samples were etched in 48% HF and the fission tracks counted by conventional transmitted light microscopy. Relative fission cross sections are examined, along with absolute Th track production rates, interaction tracks, and a comparison of measured and calculated fission rates. The practicality of fast neutron radiography revealed by experiments to data is discussed primarily for Th/U measurements, and mixtures of other fissionable nuclei are briefly considered.

  4. Cluster radioactivity and very asymmetric fission through quasi-molecular shapes

    International Nuclear Information System (INIS)

    Royer, G.

    1997-01-01

    The decay of radioactive nuclei which emit heavy clusters like C, O, Ne, Mg and Si has been studied in the fission valley which leads one spherical nucleus towards two spherical touching nuclei before crossing the barrier. Assuming volume conservation, the deformation energy has been calculated within a generalized liquid drop model taking into account the proximity effects between the cluster and the daughter nucleus. The theoretical partial half-lives obtained within the WKB barrier penetration probability are in good agreement with the experimental data for the heaviest clusters. The Ne, Mg and Si emission looks like a very-asymmetric spontaneous fission. The 14 C radioactivity is not correctly described within the fission hypothesis. The 14 C and apparently also the 20 O are probably pre-born in the parent nucleus, the emission being similar to the α decay process. (author)

  5. Study of fission barriers in neutron-rich nuclei using the (p,2p) reaction. Status of SAMURAI-experiment NP1306 SAMURAI14

    Energy Technology Data Exchange (ETDEWEB)

    Reichert, Sebastian [TU Munich (Germany); Collaboration: NP1306-SAMURAI14-Collaboration

    2015-07-01

    Violent stellar processes are currently assumed to be a major origin of the elements beyond iron and their abundances. The conditions during stellar explosions lead to the so called r-process in which the rapid capture of neutrons and subsequent β decays form heavier elements. This extension of the nuclei stops at the point when the repulsive Coulomb energy induces fission. Its recycling is one key aspect to describe the macroscopic structure of the r-process and the well known elemental abundance pattern. The RIBF at RIKEN is able to provide such neutron rich heavy element beams and a first test with the primary beam {sup 238}U was performed to understand the response of the SAMURAI spectrometer and detectors for heavy beams. The final goal is the definition of the fission barrier height with a resolution of 1 MeV (in σ) using the missing mass method using (p,2p) reactions in inverse kinematics.

  6. Behavior of actinides in the Integral Fast Reactor fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, J.C. [Louisiana State Univ., Baton Rouge, LA (United States). Nuclear Science Center; Lineberry, M.J. [Argonne National Lab., Idaho Falls, ID (United States). Technology Development Div.

    1994-06-01

    The Integral Fast Reactor (IFR) under development by Argonne National Laboratory uses metallic fuels instead of ceramics. This allows electrorefining of spent fuels and presents opportunities for recycling minor actinide elements. Four minor actinides ({sup 237}Np, {sup 240}Pu, {sup 241}Am, and {sup 243}Am) determine the waste storage requirements of spent fuel from all types of fission reactors. These nuclides behave the same as uranium and other plutonium isotopes in electrorefining, so they can be recycled back to the reactor without elaborate chemical processing. An experiment has been designed to demonstrate the effectiveness of the high-energy neutron spectra of the IFR in consuming these four nuclides and plutonium. Eighteen sets of seven actinide and five light metal targets have been selected for ten day exposure in the Experimental Breeder Reactor-2 which serves as a prototype of the IFR. Post-irradiation analyses of the exposed targets by gamma, alpha, and mass spectroscopy are used to determine nuclear reaction-rates and neutron spectra. These experimental data increase the authors` confidence in their ability to predict reaction rates in candidate IFR designs using a variety of neutron transport and diffusion programs.

  7. Actinide behavior in the Integral Fast Reactor. Final project report

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, J.C.

    1994-11-01

    The Integral Fast Reactor (IFR) under development by Argonne National Laboratory uses metallic fuels instead of ceramics. This allows electrorefining of spent fuels and presents opportunities for recycling minor actinide elements. Four minor actinides ({sup 237}Np, {sup 240}Pu, {sup 241}Am, and {sup 243}Am) determine the waste storage requirements of spent fuel from all types of fission reactors. These nuclides behave the same as uranium and other plutonium isotopes in electrorefining, so they can be recycled back to the reactor without elaborate chemical processing. An experiment has been designed to demonstrate the effectiveness of the high-energy neutron spectra of the IFR in consuming these four nuclides and weapons grade plutonium. Eighteen sets of seven actinide and five light metal targets have been selected for seven day exposure in the Experimental Breeder Reactor-II which serves as a prototype of the IFR. Post-irradiation analyses of the exposed targets by gamma, alpha, and mass spectroscopy are used to determine nuclear reaction rates and neutron spectra. These experimental data increase the authors confidence in their ability to predict reaction rates in candidate IFR designs using a variety of neutron transport and diffusion programs.

  8. Actinide behavior in the Integral Fast Reactor. Final project report

    International Nuclear Information System (INIS)

    Courtney, J.C.

    1994-11-01

    The Integral Fast Reactor (IFR) under development by Argonne National Laboratory uses metallic fuels instead of ceramics. This allows electrorefining of spent fuels and presents opportunities for recycling minor actinide elements. Four minor actinides ( 237 Np, 240 Pu, 241 Am, and 243 Am) determine the waste storage requirements of spent fuel from all types of fission reactors. These nuclides behave the same as uranium and other plutonium isotopes in electrorefining, so they can be recycled back to the reactor without elaborate chemical processing. An experiment has been designed to demonstrate the effectiveness of the high-energy neutron spectra of the IFR in consuming these four nuclides and weapons grade plutonium. Eighteen sets of seven actinide and five light metal targets have been selected for seven day exposure in the Experimental Breeder Reactor-II which serves as a prototype of the IFR. Post-irradiation analyses of the exposed targets by gamma, alpha, and mass spectroscopy are used to determine nuclear reaction rates and neutron spectra. These experimental data increase the authors confidence in their ability to predict reaction rates in candidate IFR designs using a variety of neutron transport and diffusion programs

  9. Behavior of actinides in the Integral Fast Reactor fuel cycle

    International Nuclear Information System (INIS)

    Courtney, J.C.; Lineberry, M.J.

    1994-01-01

    The Integral Fast Reactor (IFR) under development by Argonne National Laboratory uses metallic fuels instead of ceramics. This allows electrorefining of spent fuels and presents opportunities for recycling minor actinide elements. Four minor actinides ( 237 Np, 240 Pu, 241 Am, and 243 Am) determine the waste storage requirements of spent fuel from all types of fission reactors. These nuclides behave the same as uranium and other plutonium isotopes in electrorefining, so they can be recycled back to the reactor without elaborate chemical processing. An experiment has been designed to demonstrate the effectiveness of the high-energy neutron spectra of the IFR in consuming these four nuclides and plutonium. Eighteen sets of seven actinide and five light metal targets have been selected for ten day exposure in the Experimental Breeder Reactor-2 which serves as a prototype of the IFR. Post-irradiation analyses of the exposed targets by gamma, alpha, and mass spectroscopy are used to determine nuclear reaction-rates and neutron spectra. These experimental data increase the authors' confidence in their ability to predict reaction rates in candidate IFR designs using a variety of neutron transport and diffusion programs

  10. The 235U prompt fission neutron spectrum measured by the Chi-Nu project at LANSCE

    Directory of Open Access Journals (Sweden)

    Gomez J.A.

    2017-01-01

    Full Text Available The Chi-Nu experiment aims to accurately measure the prompt fission neutron spectrum for the major actinides. At the Los Alamos Neutron Science Center (LANSCE, fission can be induced with neutrons ranging from 0.7 MeV and above. Using a two arm time-of-flight (TOF technique, the fission neutrons are measured in one of two arrays: a 22-6Li glass array for lower energies, or a 54-liquid scintillator array for outgoing energies of 0.5 MeV and greater. Presented here are the collaboration's preliminary efforts at measuring the 235U PFNS.

  11. Mechanical behaviour and diffusion of gas during neutron irradiation of actinides in ceramic inert matrices

    NARCIS (Netherlands)

    Neeft, E.A.C.

    2004-01-01

    Fission of actinides from nuclear waste in inert matrices (materials without uranium) can reduce the period in time that nuclear waste is more radiotoxic than uranium ore that is the rock from which ordinary reactor fuel is made. A pioneering study is performed with the inert matrices: MgO, MgAl2O4,

  12. Nuclear fission: a review of experimental advances and phenomenology

    Science.gov (United States)

    Andreyev, A. N.; Nishio, K.; Schmidt, K.-H.

    2018-01-01

    In the last two decades, through technological, experimental and theoretical advances, the situation in experimental fission studies has changed dramatically. With the use of advanced production and detection techniques both much more detailed and precise information can now be obtained for the traditional regions of fission research and, crucially, new regions of nuclei have become routinely accessible for fission studies. This work first of all reviews the recent developments in experimental fission techniques, in particular the resurgence of transfer-induced fission reactions with light and heavy ions, the emerging use of inverse-kinematic approaches, both at Coulomb and relativistic energies, and of fission studies with radioactive beams. The emphasis on the fission-fragment mass and charge distributions will be made in this work, though some of the other fission observables, such as prompt neutron and γ-ray emission will also be reviewed. A particular attention will be given to the low-energy fission in the so far scarcely explored nuclei in the very neutron-deficient lead region. They recently became the focus for several complementary experimental studies, such as β-delayed fission with radioactive beams at ISOLDE(CERN), Coulex-induced fission of relativistic secondary beams at FRS(GSI), and several prompt fusion–fission studies. The synergy of these approaches allows a unique insight in the new region of asymmetric fission around {\\hspace{0pt}}180 Hg, recently discovered at ISOLDE. Recent extensive theoretical efforts in this region will also be outlined. The unprecedented high-quality data for fission fragments, completely identified in Z and A, by means of reactions in inverse kinematics at FRS(GSI) and VAMOS(GANIL) will be also reviewed. These experiments explored an extended range of mercury-to-californium elements, spanning from the neutron-deficient to neutron-rich nuclides, and covering both asymmetric, symmetric and transitional fission regions

  13. Dynamical features of nuclear fission

    Indian Academy of Sciences (India)

    Wheeler underestimates several observables in heavy-ion-induced ... excitation energies, there may not be sufficient nuclei near the fission barrier after the .... Dissipation in nuclear dynamics in the mean-field regime accounts for the coupling of the .... barrier for different isotopes of Fr. The lines are drawn to guide the eye.

  14. Study on neutron spectrum for effective transmutation of minor actinides in thermal reactors

    International Nuclear Information System (INIS)

    Takeda, Toshikazu; Yokoyama, Kenji

    1997-01-01

    The transmutation of minor actinides (MAs) has been investigated in thermal reactor cells using mixed oxide fuel with MAs. The effect of neutron spectra on transmutation is studied by changing the neutron spectra. Five transmutation rates are compared: direct fission incineration rate, capture transmutation rate, consumption rate, overall fission incineration rate and inventory difference transmutation rate. The relations between these transmutation rates and their dependence on the neutron spectrum were investigated. To effectively incinerate MAs it is necessary to maximize the overall fission incineration rate and the inventory difference transmutation rate. These transmutation rates become maximum when the fraction of neutrons below 1 eV is about 8% for the case where the MA addition is 1-3%. When the MA addition is over 5%, the transmutation rates become maximum for very hard neutron spectrum. (Author)

  15. Neutron rich clusters and the dynamics of fission and fusion

    International Nuclear Information System (INIS)

    Armbruster, P.

    1988-07-01

    In this lecture I want to discuss experimental evidence for the appearance of cluster aspects in the dynamics of large rearrangement processes, as fusion and fission. Clusters in the sense as used in my lecture are the strongly bound doubly magic nuclei as 20 Ca 28 48 , 28 Ni 50 78 , 132 50 Sn 82 , and 208 82 Pb 126 and the superheavy nucleus 298 114 184 . Two of these nuclei, 78 Ni and 298 114 have not yet been identified. I discuss first the experimental findings from heavy element production. Then I cover the stability of cluster aspects to intrinsic excitation energy in fusion and fission. (orig./HSI)

  16. Fission neutron spectra measurements at LANSCE - status and plans

    International Nuclear Information System (INIS)

    Haight, Robert C.; Noda, Shusaku; Nelson, Ronald O.; O' Donnell, John M.; Devlin, Matt; Chatillon, Audrey; Granier, Thierry; Taieb, Julien; Laurent, Benoit; Belier, Gilbert; Becker, John A.; Wu, Ching-Yen

    2009-01-01

    A program to measure fission neutron spectra from neutron-induced fission of actinides is underway at the Los Alamos Neutron Science Center (LANSCE) in a collaboration among the CEA laboratory at Bruyeres-le-Chatel, Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The spallation source of fast neutrons at LANSCE is used to provide incident neutron energies from less than 1 MeV to 100 MeV or higher. The fission events take place in a gas-ionization fission chamber, and the time of flight from the neutron source to that chamber gives the energy of the incident neutron. Outgoing neutrons are detected by an array of organic liquid scintillator neutron detectors, and their energies are deduced from the time of flight from the fission chamber to the neutron detector. Measurements have been made of the fission neutrons from fission of 235 U, 238 U, 237 Np and 239 Pu. The range of outgoing energies measured so far is from 1 MeV to approximately 8 MeV. These partial spectra and average fission neutron energies are compared with evaluated data and with models of fission neutron emission. Results to date will be presented and a discussion of uncertainties will be given in this presentation. Future plans are to make significant improvements in the fission chambers, neutron detectors, signal processing, data acquisition and the experimental environment to provide high fidelity data including mea urements of fission neutrons below 1 MeV and improvements in the data above 8 MeV.

  17. Ternary fission in an effective liquid drop model

    International Nuclear Information System (INIS)

    Duarte, Sergio B.; Tavares, Odilon A.P.; Dimarco, A.; Goncalves, Marcello; Guzman, Fernando; Trallero-Herrera, Carlos; Rodriguez, Oscar; Garcia, Fermin

    2001-01-01

    Full text follows: The nuclear partition in three fragments has been observed in recent experiments for fission process of 252 Cf and 24 '0 Pu. We apply the Effective Liquid Drop Model (ELDM), successfully used for discussing binary cold fission and cluster emissions for a three center geometric shape parametrization, describing the quasi-molecular deformation which can lead to ternary fragmentation. A preliminary calculation for rates of these processes are performed and the results are compared to the rate of the dominant binary fission process. A large range of parent nuclei (spherical and deformed) is covered in the calculation. The purpose is to point out others possible ternary fission process experimentally measurable. (author)

  18. Identification and systematical studies of the electron-capture delayed fission (ECDF) in the lead region

    CERN Multimedia

    Pauwels, D B; Lane, J

    2008-01-01

    In our recent experiment (March 2007) at the velocity filter SHIP(GSI) we observed the electron-capture delayed fission of the odd-odd isotope $^{194}$At. This is the first unambiguous identification of this phenomenon in the very neutron-deficient nuclei in the vicinity of the proton shell closure at Z=82. In addition, the total kinetic energy (TKE) for the daughter nuclide $^{194}$Po was measured, despite the fact that this isotope does not decay via spontaneous fission. Semi-empirical analysis of the electron-capture Q$_{EC}$ values and fission barriers B$_{f}$ shows that a relatively broad island of ECDF must exist in this region of the Nuclide Chart, with some of the nuclei having unusually high ECDF probabilities. Therefore, this Proposal is intended to initiate the systematic identification and study of $\\beta$-delayed fission at ISOLDE in the very neutron-deficient lead region. Our aim is to provide unique low-energy fission data (e.g. probabilities, TKE release, fission barriers and their isospin dep...

  19. Experimental grounds for nuclear shape isomerism

    International Nuclear Information System (INIS)

    Makarenko, V.E.

    1995-11-01

    Experimental data on fission isomeric states of actinide nuclei - half lives, energies, quantum numbers, decay branches and spectroscopic properties - are discussed. Quite a few results find their explanation in the framework of nuclear shape isomerism hypothesis being the in-thing for about thirty years. Others seem to be the hints to the quasiparticle nature of fission isomers. The problem could be solved by direct measurement of nuclear spin for isomeric states. (author). 44 refs, 1 tab

  20. Insights into nuclear structure and the fission process from spontaneous fission

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, J.H.; Butler-Moore, K.; Ramayya, A.V. [Vanderbilt Univ., Nashville, TN (United States)] [and others

    1993-12-31

    The {gamma}-rays emitted following spontaneous and induced fission are rich sources of information about the structure of neutron-rich nuclei and about the fission process itself. The study of spontaneous fissioning isotopes with large Ge detector arrays are providing a wealth of such information as seen, for example, in recent reports. In this paper we present some of our most recent results on nuclear structure studies and conclusions on the fission process itself. In our work, we have employed in spontaneous fission, a triple gamma coincidence study for the first time and a high resolution, X-ray detector-{gamma}-coincidence study. These data provide powerful ways of separating the gamma rays which belong to a particular nucleus. The triple coincidence technique was used to uniquely identify the levels in {sup 136}Te and higher spin states in its N=84 isotones, {sup 138}Xe and {sup 140}Ba{sup 171}. Some other examples of the level structures observed in the low and high mass partners are presented, including a detailed analysis of the backbending of the moment of inertia in {sup 112,114,116}Pd. Finally, we present the first examples of how our analysis allows one to extract a detailed picture of the dependence of the angular momentum on the mass and atomic numbers of the fission fragments and of the long-sought neutron multiplicity distribution from zero-n to ten-n as a function of the charge and mass asymmetry.

  1. The wastes of nuclear fission

    International Nuclear Information System (INIS)

    Doubre, H.

    2005-01-01

    In this paper the author presents the problems of the radioactive wastes generated by the nuclear fission. The first part devoted to the fission phenomenon explains the incident neutron energy and the target nuclei role. The second part devoted to the nuclear wastes sources presents the production of wastes upstream of the reactors, in the reactors and why these wastes are dangerous. The third part discusses the radioactive wastes management in France (classification, laws). The last part details the associated research programs: the radionuclides separation, the disposal, the underground storage, the transmutation and the thorium cycle. (A.L.B.)

  2. Table of superdeformed nuclear bands and fission isomers

    International Nuclear Information System (INIS)

    Firestone, R.B.; Singh, B.

    1994-06-01

    A minimum in the second potential well of deformed nuclei was predicted and the associated shell gaps are illustrated in the harmonic oscillator potential shell energy surface calculations shown in this report. A strong superdeformed minimum in 152 Dy was predicted for β 2 -0.65. Subsequently, a discrete set of γ-ray transitions in 152 DY was observed and, assigned to the predicted superdeformed band. Extensive research at several laboratories has since focused on searching for other mass regions of large deformation. A new generation of γ-ray detector arrays is already producing a wealth of information about the mechanisms for feeding and deexciting superdeformed bands. These bands have been found in three distinct regions near A=l30, 150, and 190. This research extends upon previous work in the actinide region near A=240 where fission isomers were identified and also associated with the second potential well. Quadrupole moment measurements for selected cases in each mass region are consistent with assigning the bands to excitations in the second local minimum. As part of our committment to maintain nuclear structure data as current as possible in the Evaluated Nuclear Structure Reference File (ENSDF) and the Table of Isotopes, we have updated the information on superdeformed nuclear bands. As of April 1994, we have complied data from 86 superdeformed bands and 46 fission isomers identified in 73 nuclides for this report. For each nuclide there is a complete level table listing both normal and superdeformed band assignments; level energy, spin, parity, half-life, magneto moments, decay branchings; and the energies, final levels, relative intensities, multipolarities, and mixing ratios for transitions deexciting each level. Mass excess, decay energies, and proton and neutron separation energies are also provided from the evaluation of Audi and Wapstra

  3. Table of superdeformed nuclear bands and fission isomers

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, R.B. [Lawrence Berkeley Lab., CA (United States); Singh, B. [McMaster Univ., Hamilton, ON (Canada)

    1994-06-01

    A minimum in the second potential well of deformed nuclei was predicted and the associated shell gaps are illustrated in the harmonic oscillator potential shell energy surface calculations shown in this report. A strong superdeformed minimum in {sup 152}Dy was predicted for {beta}{sub 2}-0.65. Subsequently, a discrete set of {gamma}-ray transitions in {sup 152}DY was observed and, assigned to the predicted superdeformed band. Extensive research at several laboratories has since focused on searching for other mass regions of large deformation. A new generation of {gamma}-ray detector arrays is already producing a wealth of information about the mechanisms for feeding and deexciting superdeformed bands. These bands have been found in three distinct regions near A=l30, 150, and 190. This research extends upon previous work in the actinide region near A=240 where fission isomers were identified and also associated with the second potential well. Quadrupole moment measurements for selected cases in each mass region are consistent with assigning the bands to excitations in the second local minimum. As part of our committment to maintain nuclear structure data as current as possible in the Evaluated Nuclear Structure Reference File (ENSDF) and the Table of Isotopes, we have updated the information on superdeformed nuclear bands. As of April 1994, we have complied data from 86 superdeformed bands and 46 fission isomers identified in 73 nuclides for this report. For each nuclide there is a complete level table listing both normal and superdeformed band assignments; level energy, spin, parity, half-life, magneto moments, decay branchings; and the energies, final levels, relative intensities, multipolarities, and mixing ratios for transitions deexciting each level. Mass excess, decay energies, and proton and neutron separation energies are also provided from the evaluation of Audi and Wapstra.

  4. Facilities for preparing actinide or fission product-based targets

    CERN Document Server

    Sors, M

    1999-01-01

    Research and development work is currently in progress in France on the feasibility of transmutation of very long-lived radionuclides such as americium, blended with an inert medium such as magnesium oxide and pelletized for irradiation in a fast neutron reactor. The process is primarily designed to produce ceramics for nuclear reactors, but could also be used to produce targets for accelerators. The Actinide Development Laboratory is part of the ATALANTE complex at Marcoule, where the CEA investigates reprocessing, liquid and solid waste treatment and vitrification processes. The laboratory produces radioactive sources; after use, their constituents are recycled, notably through R and D programs requiring such materials. Recovered americium is purified, characterized and transformed for an experiment known as ECRIX, designed to demonstrate the feasibility of fabricating americium-based ceramics and to determine the reactor transmutation coefficients.

  5. Actinide neutron induced cross section measurements using the oscillation technique in the Minerve reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, B.; Leconte, P.; Gruel, A.; Antony, M.; Di-Salvo, J.; Hudelot, J.P.; Pepino, A.; Lecluze, A. [CEA Cadarache, DEN/CAD/DER/SPRC/LEPh, 13 - Saint-Paul-lez-Durance (France)

    2009-07-01

    CEA is deeply involved research programs concerning nuclear fuel advanced studies (actinides, plutonium), waste management, the scientific and technical support of French PWR reactors and EPR reactor, and innovative systems. In this framework, specific neutron integral experiments have been carried out in the critical ZPR (zero power reactor) facilities of the CEA at Cadarache such as MINERVE, EOLE and MASURCA. This paper deals with MINERVE Pool Reactor experiments. MINERVE is mainly devoted to neutronics studies of different reactor core types. The aim is to improve the knowledge of the integral absorption cross sections of actinides (OSMOSE program), of new absorbers (OCEAN program) and also for fission Products (CBU program) in thermal, epithermal and fast neutron spectra. (authors)

  6. 1982 Annual Status Report Plutonium Fuels and Actinide Programme

    International Nuclear Information System (INIS)

    Lindner, R.

    1983-01-01

    The programme of the Transuranium Institute has long included work on advanced fuels for fast breeder reactors. Study of the swelling of carbide and nitride fuels is now nearing completion, the retention of fission gases in bubbles of different sizes in the fuel having been quantified as function of burn-up and temperature. An important step forward has been achieved in the studies of the Equation of State of Nuclear Fuels up to 5000 K. Formation of some of the less abundant isotopes in PWR fuel has been determined experimentally. Aerosol formation during the fabrication of plutonium containing fuels, part of the activity Safe Handling of Plutonium Fuel has been studied. Head-End Processing of carbide fuels has continued experiments with high burn up mixed carbides. In the field of actinide research the preparation and characterisation of pure specimens is carried out. Effect of actinides on the properties of waste glasses is investigated

  7. Pyrometallurgical processes for recovery of actinide elements

    International Nuclear Information System (INIS)

    Battles, J.E.; Laidler, J.J.; McPheeters, C.C.; Miller, W.E.

    1994-01-01

    A metallic fuel alloy, nominally U-20-Pu-lOZr, is the key element of the Integral Fast Reactor (IFR) fuel cycle. Metallic fuel permits the use of an innovative, simple pyrometallurgical process, known as pyroprocessing, (the subject of this report), which features fused salt electrorefining of the spent fuel. Electrorefining separates the actinide elements from fission products, without producing a separate stream of plutonium. The plutonium-bearing product is contaminated with higher actinides and with a minor amount of rare earth fission products, making it diversion resistant while still suitable as a fuel material in the fast spectrum of the IFR core. The engineering-scale demonstration of this process will be conducted in the refurbished EBR-II Fuel Cycle Facility, which has entered the start-up phase. An additional pyrometallurgical process is under development for extracting transuranic (TRU) elements from Light Water Reactor (LWR) spent fuel in a form suitable for use as a feed to the IFR fuel cycle. Four candidate extraction processes have been investigated and shown to be chemically feasible. The main steps in each process are oxide reduction with calcium or lithium, regeneration of the reductant and recycle of the salt, and separation of the TRU product from the bulk uranium. Two processes, referred to as the lithium and salt transport (calcium reductant) processes, have been selected for engineering-scale demonstration, which is expected to start in late 1993. An integral part of pyroprocessing development is the treatment and packaging of high-level waste materials arising from the operations, along with the qualification of these waste forms for disposal in a geologic repository

  8. Pyrometallurgical processes for recovery of actinide elements

    Energy Technology Data Exchange (ETDEWEB)

    Battles, J.E.; Laidler, J.J.; McPheeters, C.C.; Miller, W.E.

    1994-01-01

    A metallic fuel alloy, nominally U-20-Pu-lOZr, is the key element of the Integral Fast Reactor (IFR) fuel cycle. Metallic fuel permits the use of an innovative, simple pyrometallurgical process, known as pyroprocessing, (the subject of this report), which features fused salt electrorefining of the spent fuel. Electrorefining separates the actinide elements from fission products, without producing a separate stream of plutonium. The plutonium-bearing product is contaminated with higher actinides and with a minor amount of rare earth fission products, making it diversion resistant while still suitable as a fuel material in the fast spectrum of the IFR core. The engineering-scale demonstration of this process will be conducted in the refurbished EBR-II Fuel Cycle Facility, which has entered the start-up phase. An additional pyrometallurgical process is under development for extracting transuranic (TRU) elements from Light Water Reactor (LWR) spent fuel in a form suitable for use as a feed to the IFR fuel cycle. Four candidate extraction processes have been investigated and shown to be chemically feasible. The main steps in each process are oxide reduction with calcium or lithium, regeneration of the reductant and recycle of the salt, and separation of the TRU product from the bulk uranium. Two processes, referred to as the lithium and salt transport (calcium reductant) processes, have been selected for engineering-scale demonstration, which is expected to start in late 1993. An integral part of pyroprocessing development is the treatment and packaging of high-level waste materials arising from the operations, along with the qualification of these waste forms for disposal in a geologic repository.

  9. Validation of actinide nuclear data from ENDF/B-V, INDL/A-83 and JENDL-2

    International Nuclear Information System (INIS)

    Paviotti Corcuera, R.; Moraes, M. de

    1988-11-01

    Resonance integrals and fission spectrum averaged cross sections are calculated for the actinides of ENDF/B-V, INDL/A-83 and JENDL-2. The results are compared with each other and with experimental data when available. The experimental data are scarce and there exist large differences among data from different libraries. (author). 16 refs, 4 tabs

  10. α decay chains in 271-294115 superheavy nuclei

    International Nuclear Information System (INIS)

    Santhosh, K. P.; Priyanka, B.; Joseph, Jayesh George; Sahadevan, Sabina

    2011-01-01

    α decay of 271-294 115 superheavy nuclei is studied using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The predicted α half-lives of 287 115 and 288 115 nuclei and their decay products are in good agreement with experimental values. Comparison of α and spontaneous fission half-lives predicts four-α chains and three-α chains, respectively, from 287 115 and 288 115 nuclei and are in agreement with experimental observation. Our study predicts two-α chains from 273,274,289 115, three-α chains from 275 115, and four-α chains consistently from 284,285,286 115 nuclei. These observations will be useful for further experimental investigation in this region.

  11. A reconsideration of fission fragment angular distributions from nuclei of high spin

    International Nuclear Information System (INIS)

    Vaz, L.C.; Alexander, J.M.

    1983-01-01

    It has often been stated that fission fragment angular anisotropy, as predicted by equilibrium statistical theory, should disappear with increasing spin of the composite nucleus. However, several recent experimental studies reveal strong anisotropies for fission fragments from high-spin nuclear systems. We discuss this apparent discrepancy and its relationship to the rigid-rotor approximation used in the standard theory. A systematic comparison is given for fission fragment anisotropies from many experiments via the empirical parameters K 0 2 and Ssub(eff). These systematics indicate a strong regularity, provided one allows for the perturbing effects of fission after transfer reactions. Many of the observed anisotropies exceed the predictions of the standard theory, but, as these predictions are based on a rigid rotor model, this does not seem particularly noteworthy. (orig.)

  12. Neutron rich nuclei around 132Sn

    International Nuclear Information System (INIS)

    Bhattacharya, Sarmishtha

    2016-01-01

    The neutron rich nuclei with few particles or holes in 132 Sn have various experimental and theoretical interest to understand the evolution of nuclear structure around the doubly magic shell closure Z=50 and N=82. Some of the exotic neutron rich nuclei in this mass region are situated near waiting points in the r-process path and are of special astrophysical interest. Neutron rich nuclei near 132 Sn have been studied using fission fragment spectroscopy. The lifetime of low lying isomeric states have been precisely measured and the beta decay from the ground and isomeric states have been characterized using gamma-ray spectroscopy

  13. Entrance channel influence on the formation and decay of hot nuclei

    International Nuclear Information System (INIS)

    Harar, S.

    1987-04-01

    Different entrance channels have been investigated to form very hot nuclei and to study their decay properties. i) Argon and Nickel projectiles accelerated around the Fermi energy show that central collisions induce momentum transfers to target nuclei which are proportional to the mass of the projectile and not to its velocities in the studied energy range. The preequilibrium model fits nicely the experimental results. The decay properties of the fission products for hot nuclei will be presented. Both head-on collisions and peripheral massive transfers contribute to the formation of very excited nuclei. The question of the influence of the energy deposit in the composite like system in limiting their yields is discussed. ii) Investigations have been also achieved with alpha projectiles at much higher incident energy (around 1 GeV/u). It is shown that hot and thermalized nuclei are also formed even when the nucleon-nucleon collisions are predominant. A sensitive parameter of the transition from binary fission to multifragmentation seems to be the energy deposit in the target residues rather than the projectile velocity

  14. Asymmetry of mass and charge division in spontaneous fission

    International Nuclear Information System (INIS)

    Chakraborty, P.P.; Iyer, M.R.; Ganguly, A.K.

    The order-disorder model (ODM) has been used to explain asymmetry of mass and charge division and related phenomena in fission. According to this model the fission process involves two steps consisting of charge polarisation into two impending fragments with beta stable neutron numbers and subsequent distribution of the balance neutrons between the two. The statistics developed on the principle of equal a priori probability of all charge polarisation is used. The shell effects comes into play only in deciding stable neutron number for the charges. The total isotopic yield distribution for a number of fission reactions are presented. These show asymmetry in the actinide region which reduces with increasing mass/charge of the fissioning nuclide and bunching of the higher z peaks. The mass yields obtained therefrom for a number of fission reactions are compared with experimental results. Though there is general agreement with experimental data, the peaks of the distributions are slightly shifted away from the symmetric point and the distributions are somewhat narrower. Charge distribution parameters obtained from these results are also presented. The model predicts preference of asymmetric division for super heavy nuclides. (author)

  15. Evaluation of the (n,xn) and (n,xnf) cross sections for heavy nuclei with the statistical model

    International Nuclear Information System (INIS)

    Jary, J.

    1975-01-01

    A method was presented to calculate the (n,xn) and (n,xnf) cross sections for the heavy nuclei having mass numbers of 232 1) without fission, according to the law of conventional statistical models, in the (n,xn) process. Fission can also compete with the emission of neutrons and γ-ray for the nuclei and the excitation energy considered. The fission cross sections of 235 U and 238 U recently evaluated by Sowerby and the fission cross section of 236 U have been used to determine the other parameters needed in the calculation. The fission widths of 239 U and 238 U have been obtained by fitting the first-chance and second-chance fission plateaus of the 238 U cross section. For the fission width of 238 U, good agreement was observed between the authors' results and Landrum and others' experimental data. (Iwase, T.)

  16. Modeling a neutron rich nuclei source

    Energy Technology Data Exchange (ETDEWEB)

    Mirea, M.; Bajeat, O.; Clapier, F.; Ibrahim, F.; Mueller, A.C.; Pauwels, N.; Proust, J. [Institut de Physique Nucleaire, IN2P3/CNRS, 91 - Orsay (France); Mirea, M. [Institute of Physics and Nuclear Engineering, Tandem Lab., Bucharest (Romania)

    2000-07-01

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (author000.

  17. Modeling a neutron rich nuclei source

    International Nuclear Information System (INIS)

    Mirea, M.; Bajeat, O.; Clapier, F.; Ibrahim, F.; Mueller, A.C.; Pauwels, N.; Proust, J.; Mirea, M.

    2000-01-01

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (authors)

  18. Retention behavior of actinides and long lived fission products on Smectite rich clays

    International Nuclear Information System (INIS)

    Tomar, B.S.

    2014-01-01

    In the present work, sorption of Am(llI), Cs(I) and Sr(ll) by the Smectite rich clay from western India has been studied in detail under the varying experimental conditions, viz., pH, ionic strength, and metal ion concentration. The experimental data on sorption have been modeled using the surface complexation model. Am(llI) sorption by smectite rich clay was found to increase with the pH of the suspension. At lower pH values, the sorption decreased with increasing ionic strength of the suspension, but remained constant at higher pH values. This is reminiscent of the ion exchange mechanism at lower pH and predominantly inner sphere complexation at higher pH. Surface complexation modeling using FITEQL could successfully explain these two mechanisms operating in the different pH values. Sorption of Cs(I) and Sr(II) by the smectite rich clay was studied under the varying experimental conditions. Though the sorption of both the metal ions increased with pH, it decreased with the increasing ionic strength, at all pH values, suggesting ion exchange as the predominant mechanism at all pH values. Further, the ionic strength dependence was different in the case of Cs(I) and Sr(II) depending upon the metal ion concentration. At same metal ion concentration of Cs(I) and Sr(II) (10 -5 M) the extent of decrease with ionic strength was same in both cases, while at 10 -9 M, Cs(I), the decrease was much smaller than that at 10 -5 M. This indicates the existence of ion exchange sites having different affinities. These studies have shown high retention capacity of the clay for actinides and long lived fission products with the sorption following ion exchange mechanism in the case of Cs(I) and Sr(II) and a combination of ion exchange and surface complexation in the case of Am(III) depending upon the pH. The sorption data could be successfully explained within the framework of FITEQL, taking into account both the types of binding sites

  19. New insights into phosphate based materials for the immobilisation of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Neumeier, Stefan; Ji, Yaqi; Kowalski, Piotr M.; Kegler, Philip; Schlenz, Hartmut; Bosbach, Dirk; Deissmann, Guido [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); JARA High-Performance Computing, Aachen (Germany); Arinicheva, Yulia [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); JARA High-Performance Computing, Aachen (Germany); Forschungszentrum Juelich (Germany). Institut fuer Energie- und Klimaforschung (IEK), Werkstoffsynthese und Herstellungsverfahren (IEK-1); Heuser, Julia M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie und Klimaforschung (IEK), Nukleare Entsorgung und Reaktorsicherheit (IEK-6); JARA High-Performance Computing, Aachen (Germany); Karlsruhe Institute of Technology (Germany). Inst. of Applied Materials (IAM)

    2017-07-01

    This paper focuses on major phosphate-based ceramic materials relevant for the immobilisation of Pu, minor actinides, fission and activation products. Key points addressed include the recent progress regarding synthesis methods, the formation of solid solutions by structural incorporation of actinides or their non-radioactive surrogates and waste form fabrication by advanced sintering techniques. Particular attention is paid to the properties that govern the long-term stability of the waste forms under conditions relevant to geological disposal. The paper highlights the benefits gained from synergies of state-of-the-art experimental approaches and advanced atomistic modeling tools for addressing properties and stability of f-element-bearing phosphate materials. In conclusion, this article provides a perspective on the recent advancements in the understanding of phosphate based ceramics and their properties with respect to their application as nuclear waste forms.

  20. Minor actinides transmutation scenario studies with PWRs, FRs and moderated targets

    International Nuclear Information System (INIS)

    Grouiller, J.P.; Pillon, S.; Saint Jean, C. de; Varaine, F.; Leyval, L.; Vambenepe, G.; Carlier, B.

    2003-01-01

    Using current technologies, we have demonstrated in this study that it is theoretically possible to obtain different minor actinide transmutation scenarios with a significant gain on the waste radiotoxicity inventory. The handling of objects with Am+Cm entails the significant increase of penetrating radiation sources (neutron and γ) whatever mixed scenario is envisioned; the PWR and FR scenario involving the recycling of Am + Cm in the form of targets results in the lowest flow. In the light of these outcomes, the detailed studies has allowed to design a target sub assembly with a high fission rate (90%) and define a drawing up of reprocessing diagram with the plant head, the minor actinide separation processes (PUREX, DIAMEX and SANEX). Some technological difficulties appear in manipulating curium, principally in manufacturing where the wet process ('sol-gel') is not acquired for (Am+Cm). (author)