4,243 research outputs found
CALCULATION OF NEUTRON-CAPTURE REACTIONS CONTRIBUTION TO ENERGY RELEASE IN VVER-1000 USING SERPENT CODE
Calculating the energy release in fuel elements is an important aspect of the modeling and design of nuclear reactors. Most of the energy is produced by fission, but a non-negligible percentage is coming from neutron capture reactions, such as (n, γ) or (n, α). We implement a previously developed method for the calculation of effective energy release using Serpent Monte Carlo code. We investigate the percentage of capture component in effective energy release for various models of VVER-1000 fuel: firstly, an equivalent cell, then fresh fuel assemblies of different compositions, differing in fuel enrichment and the presence of burnable absorbers. The results are compared to similar calculations previously done in MCNP 4 and MCU 5
Optimization of the self-sufficient thorium fuel cycle for CANDU power reactors
The results of optimization calculations for CANDU reactors operating in the thorium cycle are presented in this paper. Calculations were performed to validate the feasibility of operating a heavy-water thermal neutron power reactor in a self-sufficient thorium cycle. Two modes of operation were considered in the paper: the mode of preliminary accumulation of 233U in the reactor itself and the mode of operation in a self-sufficient cycle. For the mode of accumulation of 233U, it was assumed that enriched uranium or plutonium was used as additional fissile material to provide neutrons for 233U production. In the self-sufficient mode of operation, the mass and isotopic composition of heavy nuclei unloaded from the reactor should provide (after the removal of fission products) the value of the multiplication factor of the cell in the following cycle K>1. Additionally, the task was to determine the geometry and composition of the cell for an acceptable burn up of 233U. The results obtained demonstrate that the realization of a self-sufficient thorium mode for a CANDU reactor is possible without using new technologies. The main features of the reactor ensuring a self-sufficient mode of operation are a good neutron balance and moving of fuel through the active core
Software Development for Description of Patterns in Two-Dimensional Space in Autoit by the Method of Coordinates on the Plane
In this work, we developed a program that describes patterns in two-dimensional space in the AutoIt language. Using the method of coordinates on a plane, the program code demon-strates the interdependence between the polar coordinate system and the Cartesian one
Lipschitz shadowing implies structural stability
We show that the Lipschitz shadowing property of a diffeomorphism is
equivalent to structural stability. As a corollary, we show that an expansive
diffeomorphism having the Lipschitz shadowing property is Anosov.Comment: 11 page
Study of Scintillator Strip with Wavelength Shifting Fiber and Silicon Photomultiplier
The performance of the cm plastic scintillator
strip with wavelength shifting fiber read-out by two novel photodetectors
called Silicon PhotoMultipliers (SiPMs) is discussed. The advantages of SiPM
relative to the traditional multichannel photomultiplier are shown. Light yield
and light attenuation measurements are presented. This technique can be used in
muon or calorimeter systems.Comment: 9 pages, 5 figure
Local Ferroelectricity in SrTiO_3 Thin Films
The temperature-dependent polarization of SrTiO_3 thin films is investigated
using confocal scanning optical microscopy. A homogeneous out-of-plane and
inhomogeneous in-plane ferroelectric phase are identified from images of the
linear electrooptic response. Both hysteretic and non-hysteretic behavior are
observed under a dc bias field. Unlike classical transitions in bulk
ferroelectrics, local ferroelectricity is observed at temperatures far above
the dielectric permittivity maximum. The results demonstrate the utility of
local probe experiments in understanding inhomogeneous ferroelectrics.Comment: 8 pages, 3 figures, accepted for publication in PR
Experimental evidence of planar channeling in a periodically bent crystal
The usage of a Crystalline Undulator (CU) has been identified as a promising
solution for generating powerful and monochromatic -rays. A CU was
fabricated at SSL through the grooving method, i.e., by the manufacturing of a
series of periodical grooves on the major surfaces of a crystal. The CU was
extensively characterized both morphologically via optical interferometry at
SSL and structurally via X-ray diffraction at ESRF. Then, it was finally tested
for channeling with a 400 GeV/c proton beam at CERN. The experimental results
were compared to Monte Carlo simulations. Evidence of planar channeling in the
CU was firmly observed. Finally, the emission spectrum of the positron beam
interacting with the CU was simulated for possible usage in currently existing
facilities
Uhlenbeck-Donaldson compactification for framed sheaves on projective surfaces
We construct a compactification of the Uhlenbeck-Donaldson type
for the moduli space of slope stable framed bundles. This is a kind of a moduli
space of slope semistable framed sheaves. We show that there exists a
projective morphism , where is
the moduli space of S-equivalence classes of Gieseker-semistable framed
sheaves. The space has a natural set-theoretic stratification
which allows one, via a Hitchin-Kobayashi correspondence, to compare it with
the moduli spaces of framed ideal instantons.Comment: 18 pages. v2: a few very minor changes. v3: 27 pages. Several proofs
have been considerably expanded, and more explanations have been added. v4:
28 pages. A few minor changes. Final version accepted for publication in
Math.
Meson vacuum phenomenology in a three-flavor linear sigma model with (axial-)vector mesons
We study scalar, pseudoscalar, vector, and axial-vector mesons with
non-strange and strange quantum numbers in the framework of a linear sigma
model with global chiral symmetry. We perform a
global fit of meson masses, decay widths, as well as decay amplitudes. The
quality of the fit is, for a hadronic model that does not consider
isospin-breaking effects, surprisingly good. We also investigate the question
whether the scalar states lie below or above 1 GeV and find the
scalar states above 1 GeV to be preferred as states. Additionally,
we also describe the axial-vector resonances as states.Comment: 29 pages, 4 figures, 3 tables. v2 is the updated version after
referee remarks (dilaton field discussed, a new figure added
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