[en] An innovative intense neutron generator of 14 MeV neutrons for the irradiation of future reactor materials is presented. Negative pions are produced inside a 5-10 T magnetic field by an intense deuteron beam interacting with a carbon target. The pions and the muons from pion decay in flight are collected in the backward direction and stopped in a deuterium-tritium-hydrogen target of high density. Using an 18 MW deuteron beam at 1.5 GeV (12 mA = 7.5 x 10¹⁶ d/s), circa 10¹⁶π^-/s can be generated, decaying to muons of which up to 10¹⁵ μ^-/s stop in the D/T/H mixture. Assuming X_c = 100 fusions per muon, the μCF source produces 14 MeV neutrons with a source strength of up to 10¹⁷ n/s, i.e. a neutron power of 200 kW. The environment of the second target, the neutron source itself, can be made to resemble part of the Tokamak ring to be simulated for irradiation test samples. (orig.)

[en] Neutronics calculations of the accelerator driven reactor core EAP-80 with UO₂ and PuO₂ MOX fuel elements and Pb-Bi coolant are presented in this paper. Monte Carlo optimisation computations of several schemes of the EAP-80 core with different types of fuel assemblies containing burnable absorber B4 C or H₂Zr zirconium hydride moderator were performed with the purpose to enhance the plutonium and actinide incineration rate. In the first scheme the reactor core contains burnable absorber B4 C arranged in the cladding of fuel elements with high enrichment of plutonium (up to 45%). In the second scheme H2 Zr zirconium hydride moderated zones were located in fuel elements with low enrichment (∼20%). In both schemes the incineration rate of plutonium is about two times higher than in the reference EAP-80 core and at the same time the power density distribution remains significantly unchanged compared to the reference core. A hybrid core containing two fuel zones one of which is the inner fuel region with UO₂ and PuO₂ high enrichment plutonium fuel and the second one is the outer region with fuel elements containing zirconium hydride layer was also considered. Evolution of neutronics parameters and actinide transmutation rates during the fuel burn-up is presented. Calculations were performed using the MCNP-4B code and the SCALE 4.3 computational system. (author)

[en] Negative pion production by deuterons on light nuclei has been considered in the framework of the intranuclear cascade model. Characteristics of secondary particles have been calculated by means of the internuclear cascade model for C and Be extended targets. A satisfactory agreement with experimental data for thin and extended targets has been found for different deuteron energies. Dependencies of pion yield on the target size and deuteron energy have been analyzed in detail. (orig.)

[en] The calculation of fission product yields for reactions induced by intermediate energy particles have been performed with the help of the Fong statistical model and different approaches for nuclear level density calculations. The Fermi-gas model, the generalized superfluid model and an approximate approach were applied to obtain the nuclear level densities of fission fragments. It is shown that the approaches disregarding the attenuation of the shell effects in nuclei with increasing excitation energy do not describe the experimental fission product yields in an appropriate way. A new phenomenological approach has therefore been proposed for fission product yield calculations in the intermediate energy region of primary particles. The predictions of the approach are in a good agreement with available experimental data. (orig.)

[en] Basic features of accelerator driven reactor systems were investigated. The sensitivity of the calculation of reactor parameters to the selection of calculation models, approximations and uncertainty of input parameters was examined. Effective criticality factor, source criticality factor, particle spectra, energy deposition, radiation damage rate for structural materials, Doppler coefficient have been calculated for different core design. (orig.)

[en] Computations of the incineration parameters for mixed PuO₂ and UO₂ fuel at the beginning of fuel cycle of the subcritical Energy Amplifier Prototype (EAP-80) driven by 0.6 GeV proton beam were performed. Monte Carlo codes SITHA and MCNP4a(b) were used for computations of the neutron multiplicity and reaction rates. Heterogeneous effect in parameter k_eff for considered reactor is about 1 %. Incineration rate of ²³⁹Pu is about 0.14 kg/(MW.yr), while the breeding rate of Pu actinides is 0.06 kg/(MW.yr). (author)

[en] The results Monte Carlo simulations of an intense neutron source based on muon catalyzed fusion process are presented. A deuteron beam is directed onto a cylindrical carbon target, located in vacuum converter chamber with a strong solenoidal magnetic field. The produced pions and muons which originate from pion decay are guided along magnetic field to a DT-synthesizer. Pion production in the primary target is simulated by means of Intranuclear and Internuclear cascade codes developed in INR, Moscow, while pion and muon transport process is studied by using a Monte Carlo code originated at CERN. The main purpose of the work is to calculate the pion and muon utilization efficiency taking into account the pion absorption in the primary target as well as all other losses of pions and muons in the converter and DT-cell walls. Preliminary estimations demonstrate the possibility to reach the level of 1014 n/s/cm² for the neutron flux. (J.U.). 3 tabs., 4 figs., 8 refs

[en] Computer software elaborated for numerical studies of particle transport in complex heterogeneous media is described. The software includes the CASCADE code for simulation of high energy particles (with energies above 20 MeV), the MCNP-4B module for tracking of low-energy neutrons (below 20 MeV) to thermal energies, routines providing interface between high-energy and low-energy transport codes and routines for data preparation and description of special features incorporated in physical modelling (geometry and composition, a-particle pre-compound spectra, description of angular distributions, etc.). Analysis of sensitivity of the models to the variation of model parameters, to the approximations and the uncertainty of input parameters was performed. Results of calculations performed for sub-critical reactor are presented. (author)

[en] The authors present a design study for a new intense 14-MeV neutron source based on muon catalyzed fusion (μCF) as required for open-quotes first wallclose quotes and blanket materials research of future fusion reactors. Negative pions are produced inside a 5-10 T magnetic field by an intense deuteron beam interacting with a 30-50 cm long carbon target. Muons from pion decay in flight are collected in the backward direction and stopped in a deuterium-tritium gas-cell of high density. With an 18 MW deuteron beam at 1.5 GeV ∼ 10¹⁶π^-/s can be generated decaying to muons of which up to 10¹⁵μ^-/s stop in a dt target. Assuming X_c = 100 fusions per muon, the source strength reaches 10¹⁷ 14-MeV neutrons/s which is a power of 200 kW. The achievable neutron fluxes are up to 10¹⁴/(cm²·s) (10 dpa/y) in irradiation volumes of several liters. These numbers, however, do not represent a technological limit. Compared with neutron production by low energy beams (d-Li stripping), this source has about the same power efficiency for neutron generation and the advantage of producing the original 14-MeV fusion spectrum without tails and isotropically into 4π solid angle. In addition, the power density and heat load of the primary target are a considerably smaller problem. The environment of the secondary target, the neutron source itself, can be made to resemble part of the Tokamak ring to be simulated. The noninteracting part of the beam (30-40%) can be dumped separately or reused for another facility (e.g. a spallation neutron source or for element transmutation)

[en] Theoretical models and computer codes were selected for the purpose of the study of activation of irradiated medium of the primary target of accelerator-driven sub-critical reactor. The target is envisaged to be a liquid flow of molten lead or lead-bismuth eutectic alloy which is irradiated with the beam of protons accelerated to intermediate energies of the order of 1 GeV. External spallation neutron source is thus formed. Models and codes selected are presented in the present paper. Special attention is paid to the choice of appropriate data libraries. Some results of calculations of activation of heavy-metal targets are presented and compared with those obtained by other authors. Comparison of two types of targets, namely pure molten lead and lead-bismuth eutectic, is made. (author)