Peculiarities of influence of radiation defects on photoconductivity of silicon irradiated by fast neutrons

2010 ◽  
Vol 46 (4) ◽  
pp. 298-300
Author(s):  
M. Karimov ◽  
Sh. Makhkamov ◽  
Sh. A. Makhmudov ◽  
R. A. Muminov ◽  
A. Z. Rakhmatov ◽  
...  
Keyword(s):  
Fast Neutrons ◽  
Radiation Defects

scholarly journals Computer Modeling of Displacement Cascades in Beryllium Irradiated with Intensive Neutron Flux

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
T. Troev ◽  
N. Nankov ◽  
L. Petrov ◽  
E. Popov
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Computer Modeling ◽  
Computer Simulations ◽  
Neutron Fluence ◽  
Fast Neutrons ◽  
Radiation Defects ◽  
Helium Concentration ◽  
Vacancy Clusters ◽  
Displacement Cascades

Computer simulations of the radiation defects created in beryllium irradiated by fast neutrons (E>0.1 MeV) using the Geant4 and SRIM packages were carried out. The atom cascade displacements in Be at a neutron fluence of 1.6×1020 n/cm2 were determined to be 0.06 dpa and the helium concentration was calculated to be 168 appm. The concentration of 6Li has been estimated to be 5% in comparison to the He concentration. Nanoscale calculations were done in 30×30×30 nm cube of fast neutron-irradiated Be. A correlation between the Be primary knock-on atom (PKA) energies and the damage cascades has been established. The final defect distributions of single vacancies, divacancies, and small vacancy clusters were examined. Our results indicate that the damages caused by He atoms are about 3 times less than damages caused by Be primary knock-on atoms (PKAs).

scholarly journals On models for estimating the post-radiation defect state of the -phase

2020 ◽  
pp. 47-60
Author(s):  
V. I. Bobrovskii ◽  
Keyword(s):  
Neutron Diffraction ◽  
Fast Neutrons ◽  
Defect State ◽  
Radiation Defects ◽  
Structural Effects ◽  
X Ray ◽  
Reactor Steels ◽  
Post Radiation ◽  
Antisite Defects ◽  
Initial Crystal

Processes that take place in the precipitates of -phase under irradiation with fast neutrons are topical and draw attention when one searches for ways of improving radiation resistance of structural reactor steels. A special feature of these processes is that the formation of vacancies and interstices proceeds at the background of a disordering of the initial crystal lattice, which mani-fests itself in the formation of antisite defects. X-ray and neutron diffraction techniques are efficient tools of studying changes that occur in the post-radiation structural state of such systems. However, interpretation of the experimental results calls for more complicated models for the description of structural effects exerted by accumulation of radiation defects in the material than those developed before for elementary metals. Several models are proposed in this paper.

The Influence of Power Mode on Ir-Leds Resistance to the Irradiation with Fast Neutrons

2015 ◽  
Vol 770 ◽  
pp. 518-521 ◽  
Author(s):  
A.V. Gradoboev ◽  
V.V. Sednev
Keyword(s):  
Fast Neutrons ◽  
Radiation Defects ◽  
Emissive Power ◽  
Defective Structure ◽  
Second Stage ◽  
Whole Process ◽  
Forward Current ◽  
Fast Neutron Irradiation ◽  
Power Mode ◽  
Partial Annealing

In this paper we present the results of investigation of the power mode influence on the resistance to fast neutron irradiation of IR-LEDs based on AlGaAs heterostructures. The investigation shows that there are 2 stages of LED emissive power lowering. At the first stage the emissive power decreases due to reorganization of existing defective structure. At the second stage it happens as the result of radiation defects introduction. The rate of defects introduction that influences the emissive power lowering at the first stage in the space charge region of the embedded p-n junction is higher than in the neutral region. The forward current flowing under irradiation results in partial annealing of introduced defects and consequently to resistance growth at the first stage of emissive power lowering. The LED power mode doesn’t contribute essentially to the power lowering at the second stage while observed difference is due to decrease of contribution of the first stage to the whole process of emissive power lowering.

Development of the design method for the optimal design of the Neutron Converter experimental plant

2020 ◽  
Author(s):  
Timur Smetani ◽  
Elizaveta Gureva ◽  
Vyacheslav Andreev ◽  
Natalya Tarasova ◽  
Nikolai Andree
Keyword(s):  
Optimal Design ◽  
Flux Density ◽  
Design Process ◽  
Design Method ◽  
Fast Neutrons ◽  
Experimental Plant ◽  
Plant Design ◽  
State Technical ◽  
Research Organizations ◽  
Neutron Converter

The article discusses methods for optimizing the design of the Neutron Converter research plant design with parameters that are most suitable for a particular consumer. 38 similar plant structures with different materials and sources were calculated, on the basis of which the most optimal options were found. As part of the interaction between OKBM Afrikantov JSC and the Nizhny Novgorod State Technical University named after R. E. Alekseev, the Neutron Converter research plant was designed and assembled. The universal neutron converter is a device for converting a stream of fast neutrons emitted by isotopic sources into a "standardized" value of flux density with known parameters in the volume of the central part of the product, which is the working part of the universal neutron converter. To supply neutron converters to other customer organizations (universities, research organizations and collective centers), it is necessary to take into account the experience of operating an existing facility, as well as rationalize the design process of each specific instance in accordance with the requirements of the customer.

Proposed Solutions to Achieve Nuclear Fusion

Engevista ◽  
2017 ◽  
Vol 19 (5) ◽  
pp. 1496
Author(s):  
Relly Victoria Virgil Petrescu ◽  
Raffaella Aversa ◽  
Antonio Apicella ◽  
Florian Ion Petrescu
Keyword(s):  
Nuclear Reactor ◽  
Nuclear Reactions ◽  
Nuclear Fusion ◽  
Nuclear Fission ◽  
Light Nuclei ◽  
Fast Neutrons ◽  
Fusion Reactions ◽  
Nuclear Fusion Reactions ◽  
The Masses ◽  
Fusion Products

Despite research carried out around the world since the 1950s, no industrial application of fusion to energy production has yet succeeded, apart from nuclear weapons with the H-bomb, since this application does not aims at containing and controlling the reaction produced. There are, however, some other less mediated uses, such as neutron generators. The fusion of light nuclei releases enormous amounts of energy from the attraction between the nucleons due to the strong interaction (nuclear binding energy). Fusion it is with nuclear fission one of the two main types of nuclear reactions applied. The mass of the new atom obtained by the fusion is less than the sum of the masses of the two light atoms. In the process of fusion, part of the mass is transformed into energy in its simplest form: heat. This loss is explained by the Einstein known formula E=mc2. Unlike nuclear fission, the fusion products themselves (mainly helium 4) are not radioactive, but when the reaction is used to emit fast neutrons, they can transform the nuclei that capture them into isotopes that some of them can be radioactive. In order to be able to start and to be maintained with the success the nuclear fusion reactions, it is first necessary to know all this reactions very well. This means that it is necessary to know both the main reactions that may take place in a nuclear reactor and their sense and effects. The main aim is to choose and coupling the most convenient reactions, forcing by technical means for their production in the reactor. Taking into account that there are a multitude of possible variants, it is necessary to consider in advance the solutions that we consider them optimal. The paper takes into account both variants of nuclear fusion, and cold and hot. For each variant will be mentioned the minimum necessary specifications.

Study of nickel-molybdenum catalysts for methanation of carbon monoxide

1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Minor Component ◽  
Fast Neutrons ◽  
Scanning Calorimetry ◽  
Low Concentrations ◽  
Γ Rays ◽  
Molybdenum Catalysts ◽  
Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

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