Modeling and control of xenon oscillations in thermal neutron reactors

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.

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Proposed Solutions to Achieve Nuclear Fusion

Engevista ◽

10.22409/engevista.v19i5.968 ◽

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.

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Thermal waves emitted by moving sources and the Doppler effect

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2021.121098 ◽

2021 ◽

Vol 176 ◽

pp. 121098

Author(s):

Roberto Li Voti ◽

Mario Bertolotti

Keyword(s):

Doppler Effect ◽

Thermal Waves ◽

Moving Sources ◽

The Doppler Effect

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The Doppler effect is the same for both optics and acoustics

Optik ◽

10.1016/j.ijleo.2021.167565 ◽

2021 ◽

pp. 167565

Author(s):

Shukri Klinaku

Keyword(s):

Doppler Effect ◽

The Doppler Effect

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ON THE THEORY OF THE DOPPLER EFFECT IN A MOVING MEDIUM

Modern Physics Letters A ◽

10.1142/s0217732398000024 ◽

1998 ◽

Vol 13 (01) ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

BRUNO BERTOTTI

Keyword(s):

Solar Wind ◽

Doppler Effect ◽

Dispersive Medium ◽

Time Derivative ◽

Optical Path ◽

Moving Medium ◽

Perturbation Theorem ◽

Hamiltonian Theory ◽

The Doppler Effect ◽

Definition Of

The increase in the accuracy of Doppler measurements in space requires a rigorous definition of the observed quantity when the propagation occurs in a moving, and possibly dispersive medium, like the solar wind. This is usually done in two divergent ways: in the phase viewpoint it is the time derivative of the correction to the optical path; in the ray viewpoint the signal is obtained form the deflection produced in the ray. They can be reconciled by using the time derivative of the optical path in the Lagrangian sense, i.e. differentiating from ray to ray. To rigorously derive this result an understanding, through relativistic Hamiltonian theory, of the delicate interplay between rays and phase is required; a general perturbation theorem which generalizes the concept of the Doppler effect as a Lagrangian derivative is proved. Relativistic retardation corrections O(v) are obtained, well within the expected sensitivity of Doppler experiments near solar conjunction.

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