scholarly journals Dosimetry of fast neutrons in 1W nuclear reactor with plastic nuclear-track detectors.

RADIOISOTOPES ◽  
1989 ◽  
Vol 38 (9) ◽  
pp. 359-365 ◽  
Author(s):  
Shiro YASUBUCHI ◽  
Masaharu HOSHI ◽  
Tetsuo ITOH ◽  
Saemi HISANAGA ◽  
Takeo NIWA ◽  
...  
Engevista ◽  
2017 ◽  
Vol 19 (5) ◽  
pp. 1496
Author(s):  
Relly Victoria Virgil Petrescu ◽  
Raffaella Aversa ◽  
Antonio Apicella ◽  
Florian Ion Petrescu

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.


2017 ◽  
Vol 106 ◽  
pp. 262-266 ◽  
Author(s):  
Iva Ambrožová ◽  
Kateřina Pachnerová Brabcová ◽  
Jan Kubančák ◽  
Jakub Šlegl ◽  
Raisa V. Tolochek ◽  
...  

2020 ◽  
Vol 6 ◽  
pp. 48
Author(s):  
Bertrand Mercier ◽  
Zeng Ziliang ◽  
Chen Liyi ◽  
Shao Nuoya

We study axial core oscillations due to xenon poisoning in thermal neutron nuclear reactors with simple 1D models: a linear one-group model, a linear two-group model, and a non-linear model taking the Doppler effect into account. Even though nuclear reactor operators have some 3D computer codes to simulate such phenomena, we think that simple models are useful to identify the sensitive parameters, and study the efficiency of basic control laws. Our results are that, for the one-group model, if we denote the migration area by M 2 and by H the height of the core, the sensitive parameter is H/M. H being fixed, for the 2 groups model, there are still 2 sensitive parameters, the first one being replaced by M12+M22 where M12 denotes the migration area for fast neutrons and M22 the migration area for thermal neutrons. We show that the Doppler effect reduces the instability of xenon oscillations in a significant way. Finally, we show that some proportional/integral/derivative (PID) feedback control law can damp out xenon oscillations in a similar way to the well-known Shimazu control law [Y. Shimazu, Continuous guidance procedure for xenon oscillation control, J. Nucl. Sci. Technol. 32, 1159 (1995)]. The numerical models described in our paper have been applied to PWR.


The conditions under which an exponential assembly may be used to determine control rod effectiveness are considered. It is concluded that a necessary condition for measurements to be analysed by simple theory is that the neutron energy spectrum perturbation produced by the rod should not extend over the whole volume of the assembly: the unperturbed asymptotic spectrum should be regained within the pile. Experiments show this to be the case for the largest rod used in the present experiments. Neutron balance equations in two energy groups for a square subcritical assembly with a cylindrical absorber along the axis are outlined. Measurements made in a graphite-natural uranium exponential pile are presented for boron steel, cadmium and mild steel control elements, all in the form of circular tubes ranging from 0.625 to 3.375 in. outer diameter. The results are discussed in terms of thermal neutron extrapolation lengths derived from Kushneriuk & McKay (1954). They indicate that absorption of thermal neutrons accounts for some 80% of the total effect in the case of boron steel, a larger proportion for cadmium and almost the whole effect for mild steel. The effect of placing moderating materials in the centre of the rods is investigated. For boron steel and cadmium increases in effectiveness of up to 20% are observed with moderating inserts of a hydrogenous material, while graphite is found to produce no significant change. Hydrogenous inserts increase the effectiveness by up to 40% with mild steel rods, but the effect appears to be attributable mainly to absorption of thermal neutrons by the inserts, rather than to moderation of fast neutrons. The results show very good internal consistency, supporting the validity of the technique. The sensitivity of the method appears comparable with that of measurements on a critical system with a similar lattice.


PLoS ONE ◽  
2017 ◽  
Vol 12 (6) ◽  
pp. e0178472 ◽  
Author(s):  
Satoshi Kodaira ◽  
Huizi Keiko Li ◽  
Teruaki Konishi ◽  
Hisashi Kitamura ◽  
Mieko Kurano ◽  
...  

1991 ◽  
Vol 27 (4) ◽  
pp. 202-205
Author(s):  
H. R. Moustafa ◽  
M. S. Abdel-Wahab ◽  
N. El Enany ◽  
S. El Fiki ◽  
M. A. Sharaf ◽  
...  

2009 ◽  
Vol 1215 ◽  
Author(s):  
Laurence Luneville ◽  
David Simeone ◽  
Gianguido Baldinozzi ◽  
Dominique Gosset ◽  
yves serruys

AbstractEven if the Binary Collision Approximation does not take into account relaxation processes at the end of the displacement cascade, the amount of displaced atoms calculated within this framework can be used to compare damages induced by different facilities like pressurized water reactors (PWR), fast breeder reactors (FBR), high temperature reactors (HTR) and ion beam facilities on a defined material. In this paper, a formalism is presented to evaluate the displacement cross-sections pointing out the effect of the anisotropy of nuclear reactions. From this formalism, the impact of fast neutrons (with a kinetic energy En superior to 1 MeV) is accurately described. This point allows calculating accurately the displacement per atom rates as well as primary and weighted recoil spectra. Such spectra provide useful information to select masses and energies of ions to perform realistic experiments in ion beam facilities.


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