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Articoli di riviste sul tema "Nuclear fission"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 2 novembre 2024

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1

Huynh, Tan-Dat, Sébastien Lahaye e Aimé Tsilanizara. "Use of correlations for neutron induced fission yields in DARWIN/PEPIN2 Uncertainty Quantification". EPJ Web of Conferences 302 (2024): 07009. http://dx.doi.org/10.1051/epjconf/202430207009.

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Uncertainty quantification on Decay Heat is of utmost importance for the safety evaluations linked to nuclear waste management. International nuclear data libraries like JEFF, ENDF/B or JENDL provide evaluations on independent fission yields, but generally no correlations between those fission yields. With those data, independent fission yields can be considered as the most important contributor to the Decay Heat uncertainty. Nevertheless, other data are available, like correlation matrices for some fissile systems, or the use of fission yields by mass. Complete correlation matrices appear in nuclear data libraries, like JEFF-4, but are still very scares as only the most prominent fissile systems for nuclear reactor applications have been added. Another approach is to consider the use of the fission yields by mass, which uncertainty is smaller than those of independent fission yields, and adding a constraint when propagating uncertainties. In the work, we show the impact of considering the fission yields by mass, as it was implemented in DARWIN/PEPIN2.4.8. We compare DARWIN/PEPIN2.4.8 results, obtained on a first order direct perturbation approach, with a random sampling method through the use of an URANIE/MENDEL scheme.

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2

Holbert, Keith E. "A Study of the Minimum Thermal Power of a Nuclear Reactor". Journal of Nuclear Engineering 2, n. 4 (20 ottobre 2021): 412–21. http://dx.doi.org/10.3390/jne2040031.

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The minimum mass for a critical reactor is well studied whereas the minimum heat production from a nuclear reactor has received little attention. The thermal power of a (sub)critical reactor originates from fission as well as radioactive decay. Fission includes neutron-induced and spontaneous fission. For an idealized critical core, we find that the minimum theoretical power is ER/Λ, whereas for a subcritical reactor comprising fissionable material undergoing spontaneous fission, the minimum power is dictated by subcritical multiplication. Interestingly, radioisotopic heat generation exceeds the minimum theoretical fission power for most of the fissile materials examined in this study.

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3

SCHNEIDER, ERICH, e WILLIAM C. SAILOR. "Nuclear Fission". Science & Global Security 14, n. 2-3 (dicembre 2006): 183–211. http://dx.doi.org/10.1080/08929880600993139.

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4

Verbeke, Jérôme M., Odile Petit, Abdelhazize Chebboubi e Olivier Litaize. "Correlated Production and Analog Transport of Fission Neutrons and Photons using Fission Models FREYA, FIFRELIN and the Monte Carlo Code TRIPOLI-4® ." EPJ Web of Conferences 170 (2018): 01019. http://dx.doi.org/10.1051/epjconf/201817001019.

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Fission modeling in general-purpose Monte Carlo transport codes often relies on average nuclear data provided by international evaluation libraries. As such, only average fission multiplicities are available and correlations between fission neutrons and photons are missing. Whereas uncorrelated fission physics is usually sufficient for standard reactor core and radiation shielding calculations, correlated fission secondaries are required for specialized nuclear instrumentation and detector modeling. For coincidence counting detector optimization for instance, precise simulation of fission neutrons and photons that remain correlated in time from birth to detection is essential. New developments were recently integrated into the Monte Carlo transport code TRIPOLI-4 to model fission physics more precisely, the purpose being to access event-by-event fission events from two different fission models: FREYA and FIFRELIN. TRIPOLI-4 simulations can now be performed, either by connecting via an API to the LLNL fission library including FREYA, or by reading external fission event data files produced by FIFRELIN beforehand. These new capabilities enable us to easily compare results from Monte Carlo transport calculations using the two fission models in a nuclear instrumentation application. In the first part of this paper, broad underlying principles of the two fission models are recalled. We then present experimental measurements of neutron angular correlations for 252Cf(sf) and 240Pu(sf). The correlations were measured for several neutron kinetic energy thresholds. In the latter part of the paper, simulation results are compared to experimental data. Spontaneous fissions in 252Cf and 240Pu are modeled by FREYA or FIFRELIN. Emitted neutrons and photons are subsequently transported to an array of scintillators by TRIPOLI-4 in analog mode to preserve their correlations. Angular correlations between fission neutrons obtained independently from these TRIPOLI-4 simulations, using either FREYA or FIFRELIN, are compared to experimental results. For 240Pu(sf), the measured correlations were used to tune the model parameters.

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5

Hewitt, Paul. "NUCLEAR FISSION ENERGY". Physics Teacher 58, n. 2 (febbraio 2020): 89. http://dx.doi.org/10.1119/1.5144785.

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6

Till, Charles E. "Nuclear fission reactors". Reviews of Modern Physics 71, n. 2 (1 marzo 1999): S451—S455. http://dx.doi.org/10.1103/revmodphys.71.s451.

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7

Kuznetsov, V. I. "Delayed nuclear fission". Physics of Particles and Nuclei 30, n. 6 (novembre 1999): 666. http://dx.doi.org/10.1134/1.953123.

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8

del Barrio, M. T., e Luisen E. Herranz. "Axial Fission Gas Transport in Nuclear Fuel Rods". Defect and Diffusion Forum 283-286 (marzo 2009): 262–67. http://dx.doi.org/10.4028/www.scientific.net/ddf.283-286.262.

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Fission of fissile uranium or plutonium nucleus in nuclear fuel results in fission products. A small fraction of them are volatile and can migrate under the effect of concentration gradients to the grain boundaries of the fuel pellet. Eventually, some fission gases are released to the rod void volumes by a thermally activated process. Local transients of power generation could distort even further the already non-uniform axial power and fission gas concentration profiles in fuel rods. Most of the current fuel rod performance codes neglects these gradients and the resulting axial fission gas transport (i.e., gas mixing is considered instantaneous). Experimental evidences, however, highlight axial gas mixing as a real time-dependent process. The thermal feedback between fission gas release, gap composition and fuel temperature, make the “prompt mixing assumption” in fuel performance codes a key point to investigate due to its potential safety implications. This paper discusses the possible scenarios where axial transport can become significant. Once the scenarios are well characterized, the available database is explored and the reported models are reviewed to highlight their major advantages and shortcomings. The convection-diffusion approach is adopted to simulate the axial transport by decoupling both motion mechanisms (i.e., convection transport assumed to be instantaneous) and a stand-alone code has been developed. By using this code together with FRAPCON-3, a prospective calculation of the potential impact of axial mixing is conducted. The results show that under specific but feasible conditions, the assumption of “prompt axial mixing” could result in temperature underestimates for long periods of time. Given the coupling between fuel rod thermal state and fission gas release to the gap, fuel performance codes predictions could deviate non-conservatively. This work is framed within the CSN-CIEMAT agreement on “Thermo-Mechanical Behaviour of the Nuclear Fuel at High Burnup”.

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9

Schmitt, C., A. KELIĆ, K. H. SCHMIDT, A. HEINZ, B. JURADO e P. N. NADTOCHY. "FRAGMENTATION OF RADIOACTIVE BEAMS FOR TAILORING FISSION TRANSIENTS". International Journal of Modern Physics E 18, n. 10 (novembre 2009): 2150–54. http://dx.doi.org/10.1142/s0218301309014469.

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A novel experimental approach for studying dissipative effects in nuclear fission has been developed at GSI, Darmstadt. Fragmentation of radioactive heavy-ion beams is employed to prepare fissile nuclei in well-defined initial conditions and the fission-fragment nuclear charge distribution is used for investigating pre-saddle dynamics in detail. The undeniable manifestation of transient effects at high temperature is demonstrated and the influence of the initial deformation is clearly evidenced for the first time.

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10

Åberg, S., M. Albertsson, BG Carlsson, T. Døssing, P. Möller e J. Randrup. "Nuclear Structure Effects in Fission". Journal of Physics: Conference Series 2586, n. 1 (1 settembre 2023): 012027. http://dx.doi.org/10.1088/1742-6596/2586/1/012027.

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Abstract Three examples of nuclear structure effects in fission dynamics are discussed: (i) The appearance of a super-short symmetric mode in the fission of nuclei around 264Fm leading to two double-magic 132Sn, (ii) Fission of some super-heavy elements where the heavy cluster is focused around double-magic 208Pb, and (iii) A saw-tooth distribution in angular momenta versus the fission fragment mass in the fission of 239U. The Metropolis random walk method is used to simulate the strongly damped fission dynamics on a 5D deformation grid. The dynamics is driven by pairing-, shape- and energy-dependent level densities. When available, a good agreement with experimental data is obtained.

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11

Oprea, Cristiana, Alexandru Mihul e Alexandru Oprea. "Advanced Modelling of 238U(n,f) in a Fast Reactor Application". EPJ Web of Conferences 211 (2019): 04008. http://dx.doi.org/10.1051/epjconf/201921104008.

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Fast neutron reactors, as a possible future solution on energy demand of human society, based on fission process of 238U, request new and reliable nuclear data necessary for new generation reactors design. Fission process induced by fast neutrons on 238U was investigated. Fission observables like cross sections and their uncertainties, fission fragment mass distribution, prompt neutrons emission, isomer ratios and other parameters were obtained by using Talys computer code or programs realized by authors. Then the production of isotopes like 135,133Xe, 99Mo, 131I, 89Y as well as yields of fissile nuclei were evaluated. Obtained theoretical evaluations are compared with existing experimental data.

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12

Batyaev, V. F., M. D. Karetnikov e S. V. Sklyarov. "Active Neutron Monitoring of Nuclear Fuel Cycle Fissile Materials". EPJ Web of Conferences 225 (2020): 06011. http://dx.doi.org/10.1051/epjconf/202022506011.

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A decommissioning of nuclear fuel cycle facilities is inseparable from the problems of radioactive waste disposal. One of these problems is the categorization of a waste according to the content of beta- and alpha-emitters. Beta-emitters can be identified by existing technologies; however, the trouble arises when detecting alpha-emitting elements, primarily the long-lived members of the actinium chain with the specific activity of kBq/kg when they are spread inside a structural material. The report considers an application of an active neutron method-a differential die-away technology for reliable control of small quantities of FM. The essence of this method consists in sounding the interrogated item by pulsed thermal neutrons and recording the induced fission neutrons. The ratio of the number of fission neutrons to the number of source neutrons gives the normalized number of fission neutrons that is linked to the FM mass in the interrogated object. The work presents the scheme and principle of operation of an experimental device, as well as the results of measurement of concrete structures that contain internal traces of fissile materials. Analysis of the results shows that the proposed method allows the detection of ~ 6 mg of fissile material per kg of concrete with possible localization (cartogram) of the contaminated area.

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13

Kalshoven, Petra Tjitske. "The Nuclear/Nuclear Family". Anthropology in Action 28, n. 2 (1 giugno 2021): 44–50. http://dx.doi.org/10.3167/aia.2021.280206.

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During the COVID-19 lockdown, as households were kept separate in a bid to contain the coronavirus, morally underpinned dynamics of fission and fusion occurred, privileging the ‘nuclear family’, which is taken here in two senses: the conventional social unit of a couple and their children, on the one hand, and the togetherness promoted by the nuclear industry in North West England, on the other. Whilst Sellafield’s Nuclear family fused with its host community in an outpouring of corporate kindness and volunteering, singles bereft of nuclear families were fissioned off from social life, which led to a corrective debate in the Netherlands. Drawing out analogies from a modest comparative perspective, I posit the nuclear family as a prism affording insights into the corporate, governmental and personal management of intimacy.

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14

Petrovski, A. M., T. N. Korbut, E. A. Rudak e M. O. Kravchenko. "Accounting of the vver-1200 overload influence for fission products activities calculating". Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 64, n. 4 (11 gennaio 2020): 491–96. http://dx.doi.org/10.29235/1561-8358-2019-64-4-491-496.

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Current work is aimed at the analysis of the fission products decay influence during fuel reloading, when calculating the accumulated fission products activity for the VVER-1200 reactor fuel campaign. The Bateman problem solution based technique was used for calculations, within the framework of the two fissile nuclides approximation. The fission products producing process for the VVER-1200 reactor stationary campaign is considered, taking into account the reactor shutdown periods for refueling and without taking them into account (instant reload approximation). It was shown, that the instant reload approximation for fission products activity calculations gives the similar accurate result, as calculations with taking into account the shutdown periods. The results can be used to significantly simplify the calculations of fission product activity accumulation in nuclear power reactors.

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15

Ripani, M. "Energy from nuclear fission". EPJ Web of Conferences 189 (2018): 00013. http://dx.doi.org/10.1051/epjconf/201818900013.

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The main features of nuclear fission as a physical phenomenon will be revisited, emphasizing its peculiarities with respect to other nuclear reactions. Some basic concepts underlying the operation of nuclear reactors and the main types of reactors will be illustrated, including fast reactors, showing the most important differences among them. The nuclear cycle and radioactive nuclear waste production will be also discussed, along with the perspectives offered by next-generation nuclear assemblies being proposed. The current situation of nuclear power in the world, its role in reducing carbon emission and the available resources will be briefly illustrated.

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16

Chiba, Satoshi, e T. Yoshida. "Physics of Nuclear Fission". Journal of the Atomic Energy Society of Japan 58, n. 11 (2016): 664–68. http://dx.doi.org/10.3327/jaesjb.58.11_664.

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17

Ripani, M. "Energy from nuclear fission(*)". EPJ Web of Conferences 98 (2015): 05001. http://dx.doi.org/10.1051/epjconf/20159805001.

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18

Royer, G., F. Haddad e J. Mignen. "On nuclear ternary fission". Journal of Physics G: Nuclear and Particle Physics 18, n. 12 (1 dicembre 1992): 2015–26. http://dx.doi.org/10.1088/0954-3899/18/12/017.

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19

Bertsch, G. F., W. Loveland, W. Nazarewicz e P. Talou. "Benchmarking nuclear fission theory". Journal of Physics G: Nuclear and Particle Physics 42, n. 7 (14 maggio 2015): 077001. http://dx.doi.org/10.1088/0954-3899/42/7/077001.

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20

Ripani, M. "Energy from nuclear fission". EPJ Web of Conferences 246 (2020): 00010. http://dx.doi.org/10.1051/epjconf/202024600010.

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The physics of nuclear fission will be briefly illustrated, from the basic mechanism behind this phenomenon to the relevant physical quantities like nuclear cross sections, neutron flux and reaction products, together with the accompanying phenomenon of neutron capture and its role in determining how the fuel transforms in a nuclear reactor. The basic concepts underlying the operation of different types of nuclear reactors will be illustrated, along with the concept of fuel cycle. After touching on the aspect of safety, the current situation of nuclear power in the world, with its costs, its role in reducing carbon emissions, the available resources and finally the issues of waste management and accidents will be briefly illustrated.

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21

Hilscher, D., e H. Rossner. "Dynamics of nuclear fission". Annales de Physique 17, n. 6 (1992): 471–552. http://dx.doi.org/10.1051/anphys:01992001706047100.

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22

Ripani, M. "Energy from nuclear fission". EPJ Web of Conferences 268 (2022): 00010. http://dx.doi.org/10.1051/epjconf/202226800010.

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Abstract (sommario):

The physics of nuclear fission will be briefly illustrated, from the basic mechanism behind this phenomenon to the relevant physical quantities like nuclear cross sections, neutron flux and reaction products, together with the accompanying phenomenon of neutron capture and its role in determining how the fuel transforms in a nuclear reactor. The basic concepts underlying the operation of diﬀerent types of nuclear reactors will be illustrated, along with the concept of fuel cycle. The aspects of radioactive waste, fuel resources and safety will also be briefly illustrated.

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23

Ignatyuk, A. V., B. D. Kuz'minov, N. S. Rabotnov e B. I. Fursov. "Investigations of nuclear fission". Atomic Energy 80, n. 5 (maggio 1996): 303–9. http://dx.doi.org/10.1007/bf02418708.

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24

DEPTA, K., J. A. MARUHN, W. GREINER, W. SCHEID e A. SANDULESCU. "BIMODAL FISSION IN 258FM". Modern Physics Letters A 01, n. 06 (settembre 1986): 377–81. http://dx.doi.org/10.1142/s0217732386000464.

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Within the 2-center shell model we present an explanation for the mass and total-kinetic-energy distributions of fission products of very heavy nuclei called “bimodal fission.” For the case of 258 FM we show that the symmetric fission can be described by a 2-dimensional treatment of the elongation and neck degree of freedom. Owing to shell corrections the system fissions via two decay channels that have distinct kinetic energies.

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25

Shlenskii, M. N., e B. V. Kuteev. "APPLICATIONS OF FUSION-FISSION HYBRID SYSTEMS FOR NUCLEAR FUEL CYCLE". Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion 44, n. 2 (2021): 139–44. http://dx.doi.org/10.21517/0202-3822-2021-44-2-139-144.

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26

Kunakov, S. K., E. E. Son, Zh Bolatov e M. Kaster. "Optical spectra in helium plasma generated by nuclear fission fragments". International Journal of Mathematics and Physics 6, n. 1 (2015): 75–81. http://dx.doi.org/10.26577/2218-7987-2015-6-1-75-81.

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27

Ishizuka, Chikako, Kohsuke Tsubakihara, Satoshi Chiba, Yuichiro Sekiguchi e Shinya Wanajo. "Semi-empirical fission model for r-process based on the recent experiments and three-dimensional Langevin approach". EPJ Web of Conferences 260 (2022): 11013. http://dx.doi.org/10.1051/epjconf/202226011013.

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Nuclear fission of superheavy elements can affect the r-process nucleosynthesis via a fission cycling process. In that process, the identification of the nuclide of a fission fragment and its abundance is essential for a precise evaluation of their contribution as seed nuclei of the r-process. We have investigated the nuclear fission of SHEs from the proton-rich side to the neutron-rich side using our three-and four-dimensional Langevin models [1, 4]. This model can reproduce the experimental data on nuclear fission of actinides and SHEs, while it can only provide various quantities to each fission fragment, we also developed a semi-empirical charge distribution model based on abundant experimental data of actinides [3]. A new semi-empirical nuclear fission model for the r-process is made by combining these two models.

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28

Egidy, T. von, F. J. Hartmann, S. Schmid, W. Schmid, K. Gulda, J. Jastrzebski, W. Kurcewicz et al. "Nuclear Physics with Antiprotons". Zeitschrift für Naturforschung A 50, n. 11 (1 novembre 1995): 1077–82. http://dx.doi.org/10.1515/zna-1995-1115.

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Abstract Information on the neutron distribution in the nuclear periphery was obtained by the annihilation of stopped antiprotons and the yield of residual nuclei. The last atomic transitions of the antiproton before annihilation gives complementary results. Properties of very hot nuclei (up to 1 GeV) after annihilation of stopped antiprotons were studied by neutron emission and fission. Absolute prob abilities of fission induced by stopped and fast antiprotons were determined. The experimental data are compared with elaborate calculations taking into account the annihilation process, the fast cascade and pre-equilibrium emission, thermalisation, particle evaporation and fission.

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Higgins, Daniel, Uwe Greife, Shea Mosby e Fredrik Tovesson. "Total kinetic energy and fragment mass distributions from fission of Th-232 and U-233". EPJ Web of Conferences 193 (2018): 02003. http://dx.doi.org/10.1051/epjconf/201819302003.

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Properties of fission in Th-232 and U-233 were studied at the Los Alamos Neutron Science Center at incident neutron energies from subthermal to 40 MeV. Fission fragments are observed in coincidence using a twin ionization chamber with Frisch grids. The average total kinetic energy released from fission and fragment mass distributions are calculated from observations of energy deposited and conservation of mass and momentum. Accurate experimental measurements of these parameters are necessary to better understand the fission process in isotopes relevant to the thorium fuel cycle, in which Th-232 is used as a fertile material to generate the fissile isotope of U-233. This process mirrors the uranium breeder process used to produce Pu-239 with several potential advantages including the comparative greater abundance of thorium, inherent nuclear weapons proliferation resistance, and reduced actinide production. Thus, there is increased interest in the thorium fuel cycle to meet future energy demands and improve safety and security while increasing profitability for the nuclear power industry. This research is ongoing and preliminary results are presented.

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Kondylakis, J. S. "Theoretically and under very special applied conditions a nuclear fission reactor may explode as nuclear bomb". HNPS Proceedings 18 (23 novembre 2019): 121. http://dx.doi.org/10.12681/hnps.2558.

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This article/presentation describes a theoretical and applied research in nuclear fission reactor systems. It concerns with theoretical approaches and in very special applied cases consideration where a common nuclear fission reactor system may be considered to explode as nuclear bomb. This research gives critical impacts to the design, operation, management and philosophy of nuclear fission reactors systems. It also includes a sensitivity analysis of a particular applied problem concerning the core melting of a nuclear reactor and its deposit to the bottom of reactor vessel. Specifically, in a typical nuclear fission power reactor system of about 1000 MWe, the nuclear core material (corium) in certain cases can be melted and it may deposited in the bottom of nuclear reactor vessel. So, the nuclear criticality conditions are evaluated for a particular example case(s). Assuming an example composition of melted corium of 98 tones of U238 , 1 tone of U235 , 1 tone Pu239 and 25 tones Fe56 (supporting material) in a 5 m diameter of a finite cylindrical nuclear reactor vessel it is found that it may result in nuclear criticality above the unit. This condition corresponds to Supercritical Fast Nuclear Fission Reactor case, which may under certain very special applied conditions to nuclear explode as nuclear bomb.

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Ocherashvili, A., A. Beck, T. Bogucarska, J. M. Crochemore, G. Heger, D. Michaeli, I. Israelashvili, E. Roesgen, G. Varasano e B. Pedersen. "Fissile mass estimation using β-delayed γ-rays and neutrons from fast and epithermal induced fissions". Journal of Instrumentation 17, n. 11 (1 novembre 2022): T11012. http://dx.doi.org/10.1088/1748-0221/17/11/t11012.

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Abstract A potential method for mass estimation of shielded special nuclear materials (SNM) is proposed. The method uses fast and epithermal neutrons, generated by an external pulsed neutron source, to induce fission in SNM. The subsequent β-delayed γ-rays and neutrons, emitted by the fission products, are measured simultaneously by two 3He slab detectors and a coaxial high purity germanium (HPGe) detector, located around the tested material. Measuring simultaneously both, β-delayed γ-rays and neutrons measurement, offers improved sensitivity for fissile materials detecting. Laboratory examination of the method was performed in the Pulsed Neutron Interrogation Test Assembly (PUNITA), using CBNM (Central Bureau for Nuclear Measurements) samples of Uranium.

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Poudel, Parashu Ram. "Nuclear Energy". Himalayan Physics 5 (1 luglio 2015): 51–58. http://dx.doi.org/10.3126/hj.v5i0.12841.

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Nuclear energy is the latest energy source to be used on a large scale. It has tremendous potentiality to meet the growing demand of energy without degrading the environment. Presently the nuclear fission of some heavy elements of the periodic table produces the vast majority of nuclear energy in the direct service of humankind. So nuclear energy produced by nuclear fission and its impacts are the main focus of this article.The Himalayan Physics Year 5, Vol. 5, Kartik 2071 (Nov 2014)Page: 51-58

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33

Zhu, Shuyu, Xiaoxue Zhao, Nengchuan Shu, Haicheng Wu, Lin Liu, Yongjing Chen e Lile Liu. "Beta-delayed gamma spectra in CENDL-3.2". EPJ Web of Conferences 239 (2020): 09005. http://dx.doi.org/10.1051/epjconf/202023909005.

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A new program is developed to compute the beta delayed fission gamma spectrum, and applied to compute the spectra of n+235U, 239Pu and 241Pu fissions wherein the recent nuclear database is adopted. The results show that most spectra are well in agreement with the data from ENDF/B-VII.0 library, and some are quite different, which should be caused by the improvement of the nuclear database.

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Tamagno, P., e O. Litaize. "Impact of nuclear inertia momenta on fission observables". EPJ Web of Conferences 193 (2018): 01004. http://dx.doi.org/10.1051/epjconf/201819301004.

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Fission is probably the nuclear process the less accurately described with current models because it involves dynamics of nuclear matter with strongly coupled manybody interactions. It is thus diffcult to find models that are strongly rooted in good physics, accurate enough to reproduce target observables and that can describe many of the nuclear fission observables in a consistent way. One of the most comprehensive current modeling of the fission process relies on the fission sampling and Monte-Carlo de-excitation of the fission fragments. This model is implemented for instance in the FIFRELIN code. In this model fission fragments and their state are first sampled from pre-neutron fission yields, angular momentum distribution and excitation energy repartition law then the decay of both initial fragments is simulated. This modeling provides many observables: prompt neutron and gamma fission spectra, multiplicities and also fine decompositions: number of neutrons emitted as a function of the fragment mass, spectra per fragments, etc. This model relies on nuclear structure databases and on several basic nuclear models describing for instance gamma strength functions or level densities. Additionally some free parameters are still to be determined, namely two parameters describing the excitation energy repartition law, the spin cutoff of the heavy and light fragments and a rescaling parameter for the rotational inertia momentum of the fragments with respect of the rigid-body model. In the present work we investigate the impact of this latter parameter. For this we mainly substitute the corrected rigid-body value by a quantity obtained from a microscopic description of the fission fragment. The independent-particle model recently implemented in the CONRAD code is used to provide nucleonic wave functions that are required to compute inertia momenta with an Inglis-Belyaev cranking model. The impact of this substitution is analyzed on different fission observables provided by the FIFRELIN code.

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35

Wolfe, Bertram. "Nuclear Fission - An Emerging Nuclear Energy System". Fusion Technology 20, n. 4P2 (dicembre 1991): 561–72. http://dx.doi.org/10.13182/fst91-a11946899.

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36

Martínez-Val, José M., e Mireia Piera. "Nuclear fission sustainability with hybrid nuclear cycles". Energy Conversion and Management 48, n. 5 (maggio 2007): 1480–90. http://dx.doi.org/10.1016/j.enconman.2006.12.007.

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37

Ghosh, T. K., K. Banerjee, C. Bhattacharya, S. Bhattacharya, S. Kundu, J. K. Meena, G. Mukherjee et al. "Change over from compound nuclear fission to quasi-fission". EPJ Web of Conferences 2 (2010): 10003. http://dx.doi.org/10.1051/epjconf/20100210003.

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38

Tavares, Odilon. "Nuclear fission: abundant energy available to humanity". Ciência e Sociedade 3, n. 2 (aprile 2015): 1–34. http://dx.doi.org/10.7437/cs2317-4595/2015.03.002.

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39

STANKUNAS, GEDIMINAS. "FRACTAL MODEL OF FISSION PRODUCT RELEASE IN NUCLEAR FUEL". International Journal of Modern Physics C 23, n. 09 (settembre 2012): 1250057. http://dx.doi.org/10.1142/s012918311250057x.

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Abstract (sommario):

A model of fission gas migration in nuclear fuel pellet is proposed. Diffusion process of fission gas in granular structure of nuclear fuel with presence of inter-granular bubbles in the fuel matrix is simulated by fractional diffusion model. The Grunwald–Letnikov derivative parameter characterizes the influence of porous fuel matrix on the diffusion process of fission gas. A finite-difference method for solving fractional diffusion equations is considered. Numerical solution of diffusion equation shows correlation of fission gas release and Grunwald–Letnikov derivative parameter. Calculated profile of fission gas concentration distribution is similar to that obtained in the experimental studies. Diffusion of fission gas is modeled for real RBMK-1500 fuel operation conditions. A functional dependence of Grunwald–Letnikov derivative parameter with fuel burn-up is established.

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40

Verriere, M., M. R. Mumpower, T. Kawano e N. Schunck. "Description of the Fission Process: Nuclear Models for Fission Dynamics". EPJ Web of Conferences 242 (2020): 03005. http://dx.doi.org/10.1051/epjconf/202024203005.

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Abstract (sommario):

Nuclear fission is the splitting of a heavy nucleus into two or more fragments, a process that releases a substantial amount of energy. It is ubiquitous in modern applications, critical for national security, energy generation and reactor safeguards. Fission also plays an important role in understanding the astrophysical formation of elements in the universe. Eighty years after the discovery of the fission process, its theoretical understanding from first principles remains a great challenge. In this paper, we present promising new approaches to make more accurate predictions of fission observables.

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41

Gönnenwein, Friedrich. "Shells, Anti-Shells and Modes in nuclear Fission". EPJ Web of Conferences 193 (2018): 01001. http://dx.doi.org/10.1051/epjconf/201819301001.

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Abstract (sommario):

Fission phenomena are surveyed where fragment properties are catching the eye. Beyond the Liquid Drop the relevant properties of fragments are shell effects and nuclear pairing. Shell effects influence on mass, charge, stability and deformability of fragments. Most often only the stabilizing effects of shells are discussed and the equally frequent destabilizing effects are not mentioned. For the present purpose the terms shells and anti-shells are used in case of stabilizing and destabilizing effects, respectively. Fragment shells and anti-shells lead to fission modes with characteristic properties. A special issue is where in the course of fission these modes assume their characteristic features. Surprisingly fragment angular distributions in above- and sub-barrier fission help elucidating this question. The discussion is focussed on fission in the standard actinides.

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42

Perkasa, Yuda S., Rizal Kurniadi e Abdul Waris. "Application of TALYS code for Calculation of Fission Cross Section and Fission Yield of Several Heavy Nuclides". Indonesian Journal of Physics 20, n. 3 (3 novembre 2016): 49–53. http://dx.doi.org/10.5614/itb.ijp.2009.20.3.2.

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Nuclear data evaluation for fission cross section and fission yield had been performed by many investigators using different models of approximation theoretically. These models are encapsulated and implemented into computer codes to perform more robust nuclear reaction data calculations. TALYS is one of most successful nuclear reaction codes that used to determine fission cross section and fission yield. In this paper, TALYS code was used to calculate some fission reaction including Am-241 (n,f), Th-232 (n,f), and U-235 (n,f). These calculations are performed using different set of reaction mechanism and optical model parameter adjustment, such as fission barrier parameter, level density parameter, transmission mechanism, and so on. Reaction mechanism and parameter adjustment are selected based on reaction characteristics to obtain more accurate and reasonable result. The accuracy of calculation result are heavily depend on the reaction mechanism selection and parameter adjustment. All obtained results have been compared with ENDF nuclear data library.

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43

Wagemans, J., L. Borms, A. Kochetkov, A. Krása, C. Van Grieken e G. Vittiglio. "Nuclear instrumentation in VENUS-F". EPJ Web of Conferences 170 (2018): 04027. http://dx.doi.org/10.1051/epjconf/201817004027.

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Abstract (sommario):

VENUS-F is a fast zero power reactor with 30 wt% U fuel and Pb/Bi as a coolant simulator. Depending on the experimental configuration, various neutron spectra (fast, epithermal, and thermal islands) are present. This paper gives a review of the nuclear instrumentation that is applied for reactor control and in a large variety of physics experiments. Activation foils and fission chambers are used to measure spatial neutron flux profiles, spectrum indices, reactivity effects (with positive period and compensation method or the MSM method) and kinetic parameters (with the Rossi-alpha method). Fission chamber calibrations are performed in the standard irradiation fields of the BR1 reactor (prompt fission neutron spectrum and Maxwellian thermal neutron spectrum).

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44

Kolarik, Zdenek, e Edouard V. Renard. "Recovery of Value Fission Platinoids from Spent Nuclear Fuel". Platinum Metals Review 47, n. 2 (1 aprile 2003): 74–87. http://dx.doi.org/10.1595/003214003x4727487.

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Abstract (sommario):

Radioactive high-level liquid wastes originating from reprocessing spent nuclear fuel can be a valuable source of platinum metals. The recovery of fission palladium and rhodium is of particular interest and is being investigated worldwide. The radioactivity of fission platinoids is reduced to a non-hazardous level after decontamination from other fission products by a factor of 1010. The intrinsic radioactivity of fission palladium is weak and can be tolerated in many applications, while that of fission rhodium decays to an acceptable level only after storing for about 30 years. With emphasis on recent achievements, this paper, which covers periodical, report and patent literature, reviews the behaviour of fission platinoids in basic separation operations. Aqueous methods, such as solvent extraction, ion exchange, electrolysis, precipitation and redox reactions, are dealt with as well as pyrochemical methods, such as molten salts/metal extraction and solid phase reactions. A second part, to be published in a later issue, considers separation processes.

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45

Doizi, D., S. Reymond la Ruinaz, I. Haykal, L. Manceron, A. Perrin, V. Boudon, J. Vander Auwera, F. Kwabia tchana e M. Faye. "Analytical measurements of fission products during a severe nuclear accident". EPJ Web of Conferences 170 (2018): 08005. http://dx.doi.org/10.1051/epjconf/201817008005.

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Abstract (sommario):

The Fukushima accident emphasized the fact that ways to monitor in real time the evolution of a nuclear reactor during a severe accident remain to be developed. No fission products were monitored during twelve days; only dose rates were measured, which is not sufficient to carry out an online diagnosis of the event. The first measurements were announced with little reliability for low volatile fission products. In order to improve the safety of nuclear plants and minimize the industrial, ecological and health consequences of a severe accident, it is necessary to develop new reliable measurement systems, operating at the earliest and closest to the emission source of fission products. Through the French program ANR « Projet d’Investissement d’Avenir », the aim of the DECA-PF project (diagnosis of core degradation from fission products measurements) is to monitor in real time the release of the major fission products (krypton, xenon, gaseous forms of iodine and ruthenium) outside the nuclear reactor containment. These products are released at different times during a nuclear accident and at different states of the nuclear core degradation. Thus, monitoring these fission products gives information on the situation inside the containment and helps to apply the Severe Accident Management procedures. Analytical techniques have been proposed and evaluated. The results are discussed here.

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46

Kadmensky, S. G., e L. V. Titova. "Interference effects in nuclear fission". Bulletin of the Russian Academy of Sciences: Physics 71, n. 3 (marzo 2007): 341–45. http://dx.doi.org/10.3103/s1062873807030082.

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47

Lemaître, J. F., S. Hilaire, S. Panebianco e J. L. Sida. "Nuclear Fission Modelling with SPY". Acta Physica Polonica B 46, n. 3 (2015): 585. http://dx.doi.org/10.5506/aphyspolb.46.585.

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48

Al-Adili, A., Z. Gao, M. Lantz, A. Solders, M. Österlund e S. Pomp. "Isomer yields in nuclear fission". EPJ Web of Conferences 256 (2021): 00002. http://dx.doi.org/10.1051/epjconf/202125600002.

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Abstract (sommario):

The generation of angular momentum in the fission process is still an open question. To shed light on this topic, we started a series of measurements at the IGISOL-JYFLTRAP facility in Finland. Highprecision measurements of isomeric yield ratios (IYR) are performed with a Penning trap, partly with the aim to extract average root-mean-square (rms) quantities of fragment spin distributions. The newly installed Phase-Imaging Ion-Cyclotron Resonance (PI-ICR) technique allows the separation of masses down to tens of keV, which is suffcient to disentangle many isomers. In this paper, we first summarize the previous measurements on the neutron and proton-induced fission of uranium and thorium, e.g. the odd cadmium and indium isotopes (119 ≤ A ≤ 127). The measurements revealed systematic trends as function of mass number, which stimulated further exploration. A recent measurement was performed at IGISIOL and several new IYR data will soon be published, for the first time. Secondly, we employ the TALYS nuclear-reaction code to model one of the newly measured isomer yields. Detailed GEF and TALYS calculations are discussed for the fragment angular momentum distribution in 134I.

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49

Koshkarev, D. G., e B. Yu Sharkov. "Nuclear fission with inertial confinement". Journal of Experimental and Theoretical Physics Letters 75, n. 7 (aprile 2002): 301–3. http://dx.doi.org/10.1134/1.1485255.

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50

Cha, D., e G. F. Bertsch. "Nuclear fission with diffusive dynamics". Physical Review C 46, n. 1 (1 luglio 1992): 306–11. http://dx.doi.org/10.1103/physrevc.46.306.

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