scholarly journals On Some Fundamental Peculiarities of the Traveling Wave Reactor

2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
V. D. Rusov ◽  
V. A. Tarasov ◽  
I. V. Sharph ◽  
V. N. Vashchenko ◽  
E. P. Linnik ◽  
...  
Keyword(s):  
Cross Sections ◽  
Traveling Wave ◽  
Blow Up ◽  
Stability Loss ◽  
Wave Mode ◽  
Fuel Temperature ◽  
Burning Wave ◽  
Nuclear Burning ◽  
Flow Evolution ◽  
First Time

On the basis of the condition for nuclear burning wave existence in the neutron-multiplying media (U-Pu and Th-U cycles) we show the possibility of surmounting the so-called dpa-parameter problem and suggest an algorithm of the optimal nuclear burning wave mode adjustment, which is supposed to yield the wave parameters (fluence/neutron flux, width and speed of nuclear burning wave) that satisfy the dpa-condition associated with the tolerable level of the reactor materials radioactive stability, in particular that of the cladding materials. It is shown for the first time that the capture and fission cross sections of238U and239Pu increase with temperature within 1000–3000 K range, which under certain conditions may lead to a global loss of the nuclear burning wave stability. Some variants of the possible stability loss due to the so-called blow-up modes (anomalous nuclear fuel temperature and neutron flow evolution) are discussed and are found to possibly become a reason for a trivial violation of the traveling wave reactor internal safety.

scholarly journals Nuclear Burning Wave Concept and Theoretical Approaches for its Description

2020 ◽  
Keyword(s):  
Fast Neutron ◽  
Nuclear Fuel ◽  
Nuclear Power ◽  
Neutron Transport ◽  
Wave Mode ◽  
Nuclear Power Engineering ◽  
Power Engineering ◽  
Theoretical Approaches ◽  
Burning Wave ◽  
Nuclear Burning

After two major nuclear power plant accidents in Chernobyl (1986) and Fukushima (2011), one of the main requirements for the nuclear power engineering is the safety of the nuclear reactors in operation, as well as new nuclear power plants of the fourth generation, which are being developed now. One of such requirements is presence of the so-called “inherent safety” mechanism, which renders the uncontrolled reactor runaway impossible under any conditions, moreover, the implementation of such a mechanism should be ensured on the level of physical principles embedded in the reactor design. Another important problem of the nuclear power engineering is the need of the transition to the large-scale use of the fast-neutron breeder reactors, with which it would be possible to set up expanded reproduction of the nuclear fuel and by that means solve the problem of supplying humanity with relatively cheap energy for thousands of years. Moreover, at present an unresolved problem is the disposal of spent nuclear fuel containing radioactive nuclides with long half-lives, which presents a long-term danger to the ecology. One of the promising conceptions of the fast-neutron breeder reactor, which can, in the case of successful implementation, partially or even entirely solve the problems of the nuclear power engineering mentioned above, is the reactor that operates in the nuclear burning wave mode, which is also known as “Traveling wave reactor”, CANDLE and by some other names. This paper presents a short review of the main theoretical approaches used for description of such a physical phenomenon as slow nuclear burning (deflagration) wave in the neutron multiplication medium initially composed of the fertile material 238U or 232Th. A comparative analysis of the possibilities of different mathematical models for describing this phenomenon is performed, both for those based on the deterministic approach (i.e. solving neutron transport equations) and for models that use Monte Carlo methods. The main merits of the fast breeder reactor, working in the nuclear burning wave mode, and problems related to the practical realization of the considered concept are discussed.

scholarly journals OPTIMIZATION OF IGNITION ZONE OF ADVANCED FAST REACTOR, WORKING IN NUCLEAR BURNING WAVE MODE

2019 ◽  
pp. 80-85
Author(s):  
S. P. Fomin ◽  
A. I. Kirdin ◽  
M. S. Malovytsia ◽  
V. V. Pilipenko ◽  
N. F. Shul’ga
Keyword(s):  
Fast Reactor ◽  
Wave Mode ◽  
The Self ◽  
Smooth Transition ◽  
Fissile Material ◽  
Burning Wave ◽  
Fuel Burn ◽  
Nuclear Burning ◽  
Reactor Operating ◽  
Ignition Zone

This article deals with the problem of optimizing composition and structure of the ignition zone of the fast reactor operating in the self-sustaining mode of nuclear burning wave with the purpose of its smooth start-up and reducing fissile material amount in initial assembly. The cylindrical homogeneous reactor with the ignition zone placed in the center or near the cylinder end is considered. The analysis has been performed basing on solving the non-stationary neutron diffusion equation together with the fuel burn-up equations and the equations of nuclear kinetics for precursor nuclei of delayed neutrons, with using the radial buckling approximation. An optimized structure of the ignition zone has been proposed, which ensures a smooth transition of the reactor to the self-sustaining nuclear burning wave mode, avoiding an excessive energy release, which is observed when using a simplified scheme of ignition zone. Comparison of the startup variants with the ignition zone at the cylinder end and at its center shows the benefits of the second one.

The Mechanics of the Secondary Flows of Viscoelastic Fluids in Non-Circular Straight Tubes and the Mean Transversal Field in Pulsating Flows

2000 ◽  
Author(s):  
Dennis A. Siginer ◽  
Mario F. Letelier
Keyword(s):  
Secondary Flow ◽  
Cross Sections ◽  
Viscoelastic Fluids ◽  
Secondary Flows ◽  
Novel Approach ◽  
Transversal Field ◽  
Time Domains ◽  
Viscoelastic Liquids ◽  
First Time ◽  
Secondary Flow Field

Abstract A survey of secondary flows of viscoelastic liquids in straight tubes is given including recent work pointing at striking analogies with transversal deformations associated with the simple shearing of solid materials. The importance and implications of secondary flows of viscoelastic fluids in heat transfer enhancement are explored together with the difficulties in detecting weak secondary flows (dilute, weakly viscoelastic solutions) in a laboratory setting. Recent new work by the author and colleagues which explores for the first time the structure of the secondary flow field in the pulsating flow of a constitutively nonlinear simple fluid, whose structure is defined by a series of nested integrals over semi-infinite time domains, in straight tubes of arbitrary cross-sections is summarized. The transversal field arises at the second order of the perturbation of the nonlinear constitutive structure, and is driven by first order terms which define the linearly viscoelastic longitudinal flow in the hierarchy of superposed linear flows stemming from the perturbation of the constitutive structure. Arbitrary conduit contours are obtained through a novel approach to the concept of domain perturbation. Time averaged, mean secondary flow streamline contours are presented for the first time for triangular, square and hexagonal pipes.

scholarly journals Performance Evaluation of a Nanomaterial-Based Thermoelectric Generator with Tapered Legs

2020 ◽  
Vol 7 ◽  
pp. 48-54
Author(s):  
Marilyn A. Ebiringa ◽  
John Paul Adimonyemma ◽  
Chika Maduabuchi
Keyword(s):  
Cross Sections ◽  
Thermoelectric Generator ◽  
Bulk Material ◽  
Electrical Energy ◽  
Ansys Software ◽  
Thermoelectric Effects ◽  
Trapezoidal Shape ◽  
Solar Radiation Intensity ◽  
Geometry Configuration ◽  
First Time

A thermoelectric generator (TEG) converts thermal energy to electricity using thermoelectric effects. The amount of electrical energy produced is dependent on the thermoelectric material properties. Researchers have applied nanomaterials to TEG systems to further improve the device’s efficiency. Furthermore, the geometry of the thermoelectric legs has been varied from rectangular to trapezoidal and even X-cross sections to improve TEG’s performance further. However, up to date, a nanomaterial TEG that uses tapered thermoelectric legs has not been developed before. The most efficient nanomaterial TEGs still make use of the conventional rectangular leg geometry. Hence, for the first time since the conception of nanostructured thermoelectrics, we introduce a trapezoidal shape configuration in the device design. The leg geometries were simulated using ANSYS software and the results were post-processed in the MATLAB environment. The results show that the power density of the nanoparticle X-leg TEG was 10 times greater than that of the traditional bulk material semiconductor X-leg TEG. In addition, the optimum leg geometry configuration in a nanomaterial-based TEG is dependent on the operating solar radiation intensity.

scholarly journals CROSS-SECTIONS FOR PHOTONUCLEAR REACTIONS 93Nb(γ,n)92mNb AND 93Nb(γ,n)92tNb IN THE END-POINT BREMSSTRAHLUNG ENERGIES 36...91 MeV

2020 ◽  
pp. 148-153
Author(s):  
A.N. Vodin ◽  
O.S. Deiev ◽  
I.S. Timchenko ◽  
S.N. Olejnik ◽  
A.S. Kachan ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Maximum Energy ◽  
Reaction Cross ◽  
Bremsstrahlung Spectrum ◽  
Photonuclear Reactions ◽  
End Point ◽  
Γ Ray ◽  
First Time ◽  
Good Agreement

The flux-weighted averaged over the energy range of bremsstrahlung spectrum from reaction threshold up to the maximum energy of γ-ray cross-sections <σ(E)> of the 93Nb(γ,n)92mNb and 93Nb(γ,n)92tNb photonuclear reactions were determined by the gamma-activation method within the end-point bremsstrahlung energies Еmax = 36…91 MeV. Activation of 93Nb targets has been done by a bremsstrahlung flux using an electron beam at the linear accelerator LUE-40 at RDC "Accelerator" NSC KIPT. The γ-ray spectra of irradiated targets were registered using the HPGe detector with an energy resolution of 1.8 keV for the 1332 keV line 60Co. To control the bremsstrahlung flux we used natMo witness-targets and a reaction cross-section of 100Mo(γ,n)99Mo. Obtained experimental cross-sections <σ(E)> of the studied reactions are in good agreement with the theoretical values calculated within TALYS 1.9 code and the results of other authors. The averaged cross-sections <σ(E)> of the 93Nb(γ,n)92mNb and 93Nb(γ,n)92tNb reactions in the energy range 35...45 MeV and > 70 MeV were obtained for the first time.

scholarly journals Взаимодействие alpha-частиц keV-энергий с молекулами глицил-лейцина

2021 ◽  
Vol 47 (12) ◽  
pp. 23
Author(s):  
А.А. Басалаев ◽  
А.Г. Бузыкин ◽  
В.В. Кузьмичев ◽  
М.Н. Панов ◽  
А.В. Петров ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Cross Sections ◽  
Density Functional ◽  
Molecular Ions ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Singly Charged ◽  
Doubly Charged ◽  
First Time ◽  
Fragmentation Processes

Radiation damage to isolated glycyl-leucine (C8H16N2O3) molecules caused by interaction with He2+ ions was studied. For the first time, the relative cross sections of the main processes of changes in the charge state of the collision partners and the relative cross sections of the fragmentation processes of singly and doubly charged molecular ions formed during single collisions of glycyl-leucine molecules with ions have been obtained. The optimized geometry of the molecule and singly charged glycyl-leucine ion was calculated using the density functional theory (DFT).

Review of the Secondary Flows of Complex Fluids

2003 ◽  
Author(s):  
Dennis A. Siginer
Keyword(s):  
Secondary Flow ◽  
Cross Sections ◽  
Secondary Flows ◽  
Laboratory Setting ◽  
Transfer Enhancement ◽  
Domain Perturbation ◽  
Novel Approach ◽  
Viscoelastic Liquids ◽  
First Time ◽  
Secondary Flow Field

A survey of secondary flows of viscoelastic liquids in straight tubes is given including recent work pointing at striking analogies with transversal deformations associated with the simple shearing of solid materials. The importance and implications of secondary flows of viscoelastic fluids in heat transfer enhancement are explored together with the difficulties in detecting weak secondary flows (dilute, weakly viscoelastic solutions) in a laboratory setting. Recent new work by the author and colleagues which explores for the first time the structure of the secondary flow field in the pulsating flow of a constitutively nonlinear simple fluid in straight tubes of arbitrary cross-sections is summarized. Arbitrary conduit contours are obtained through a novel approach to the concept of domain perturbation. Time averaged, mean secondary flow streamline contours are presented for the first time for triangular, square and hexagonal pipes.

New morphological and anatomical data on the genus Fuernrohria (Apiaceae)

Phytotaxa ◽  
2020 ◽  
Vol 429 (1) ◽  
pp. 48-56
Author(s):  
BARIŞ BANİ ◽  
DUDU ÖZLEM MAVİ İDMAN
Keyword(s):  
Cross Sections ◽  
Leaf Sheath ◽  
Distribution Area ◽  
Morphological Description ◽  
Leaf Segment ◽  
Vascular Bundles ◽  
Anatomical Data ◽  
Micromorphological Characters ◽  
First Time ◽  
Stem Leaf

In this study, morphological and anatomical data (including fruit micromorphological characters) of the genus Fuernrohria were studied and compared with the related genera Grammosciadium, Caropodium and Vinogradovia. The morphological description of Fuernrohria setifolia, which is the only known species in the genus, is expanded. Photos of inflorescences, infructescences and leaves of the species taken from the wild are provided. Leaf segment and mericarps are illustrated, and also the distribution area of the genus is mapped. Anatomical features of root, stem, leaf sheath, leaf segment and fruit are presented with photographs of cross sections for each of them. Vegetative anatomical characteristics of the species and micromorphological description of fruit are given and exhibited for the first time in the present study. The results show that two important diagnostic characters for Fuernrohria are determined for the first time as “shape and size of commissural vittae in mericarps” and “number of vascular bundles in leaf cross section”.

Influence of the radial neutron reflector efficiency on the power of fast nuclear-burning-wave reactor

2020 ◽  
Vol 148 ◽  
pp. 107699
Author(s):  
S.P. Fomin ◽  
A.I. Kirdin ◽  
M.S. Malovytsia ◽  
V.V. Pilipenko ◽  
N.F. Shul’ga
Keyword(s):  
Burning Wave ◽  
Nuclear Burning
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