39 research outputs found
Spallation Neutron Production by 0.8, 1.2 and 1.6 GeV Protons on various Targets
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
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
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 = D e are presented for U(Th)-O , PyC and SiC. The silver release in advanced High-Temperature Reactors is prognosticated based an the measured data
Experimentelle Untersuchungen zum Transportverhalten von Silber in Brennstoffteilchen fuer Hochtemperaturreaktoren
SIGLEDEGerman
Messungen und Berechnungen zur Sr-90-Freisetzung aus HTR-Brennstoffelementen
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: D =3,5 10 e - 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 MW-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
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
A deep penetration experiment conducted at the Los Alamos WNR facility's Spallation Neutron Target is compared with calculations using intra-nuclear-cascade and S-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