39 research outputs found

    Spallation Neutron Production by 0.8, 1.2 and 1.6 GeV Protons on various Targets

    Full text link
    Spallation neutron production in proton induced reactions on Al, Fe, Zr, W, Pb and Th targets at 1.2 GeV and on Fe and Pb at 0.8, and 1.6 GeV measured at the SATURNE accelerator in Saclay is reported. The experimental double-differential cross-sections are compared with calculations performed with different intra-nuclear cascade models implemented in high energy transport codes. The broad angular coverage also allowed the determination of average neutron multiplicities above 2 MeV. Deficiencies in some of the models commonly used for applications are pointed out.Comment: 20 pages, 32 figures, revised version, accepted fpr publication in Phys. Rev.

    Spallation reactions. A successful interplay between modeling and applications

    Get PDF
    The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200 MeV deuterons and 400 MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. The same year R. Serber describes the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a worskhop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool.Comment: 59 pages, 54 figures, Revie

    Experimentelle Untersuchungen zum Transportverhalten von Silber in Brennstoffteilchen für Hochtemperaturreaktoren

    Get PDF
    The migrational behaviour of silver in the coated particle fuel, proposed for High-Temperature Reactors, is investigated experimentally. Data are described in the framework of the diffusion model. The diffusion coefficients are derived from the experimental data by a nonlinear least squares fit procedure. The experimental procedures and the theoretical calculations to analyse the data are described extensively. Arrhenius lines D = Do_{o} e−Q/RT^{-Q/RT} are presented for U(Th)-O2_{2} , PyC and SiC. The silver release in advanced High-Temperature Reactors is prognosticated based an the measured data

    Messungen und Berechnungen zur Sr-90-Freisetzung aus HTR-Brennstoffelementen

    No full text
    Coated fuel particles were investigated in post irradiation experiments. Sr-90-fractional releases from single particles were measured during isothermal anneals. The time-dependent fractional release curves were analyzed with the aid of simple diffusion theory and delivered temperature dependent diffusion constants. For oxide kernel material with burn-up values up to 30% fima it resulted: DSr−90_{Sr-90} =3,5 ⋅\cdot 10−5^{-5} m2sec\frac{m ^{2}}{sec} e - 409000(Joule/mol)RT\frac{409 000(Joule/mol)} {RT} Additionally some measurements were done on kernels with additives and TRISO coated particles. Moreover these data and other data from literature were used in a parametric study to determine the data's influence upon Sr-90 Core releases of 3000 MWth_{th}-plants. The results show, that all calculated forecasts remain sufficiently low as for oxide fuel, but increase to evidently higher release values as for carbide kernel materials

    Intranuclear cascade evaporation model predictions of double differential A(p,xn) neutron cross sections and comparison with experiments at 318 MeV and 800 MeV proton energy

    No full text
    The intranuclear-cascade evaporation model (INCE) as implemented in the high energy radiation transport code HETC, subsystem of HERMES (1) is used in the calculation of double differential cross sectionsl of proton induced neutron production. The investigations were done on target elements C, Al, Ta, Ni, W, Pb, and U at 318 MeV incident proton energy and on C, Al, Pb, and U at 800 MeV, respectively. The predictions of the INCE model were compared with experimental data for double differential cross sections taken at 7.5 and 30 degrees scattering angles at the Los Aamos WNR facility utilizing the Time of Flight (ToF) technique at LANL. The calculations performed here are part of a experimental-theoretical program within the LANL-KFA collaboration concernign medium energy cross section measurements mainly neutrons and state of the art computer code validations of these measurements. In general, the model predictions reproduce the correct neutron production for evaporation neutrons and are also in good agreement with the experimental data at high neutron energies. In the energy range dominated by preequilibrion processes an underestimation of experimental yields has to be remarked

    A medium energy neutron deep penetration experiment : experimental and theoretical analysis

    No full text
    A deep penetration experiment conducted at the Los Alamos WNR facility's Spallation Neutron Target is compared with calculations using intra-nuclear-cascade and SN_{N}-transport codes installed at KFA-IRE. In the experiment medium energy reactions induced by neutrons between 15 MeV and about 150 MeV inside a quasi infinite slab of iron have been measured using copper foil monitors. Details of the experimental prodedure and the theoretical methods are described. A comparison of absolute reaction rates for both experimentally and theoretically derived reactions is given. The present knowledge of the corresponding monitor reaction cross sections is discussed
    corecore