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Nuclear Reactors, Nuclear Fusion and Fusion Engineering by A. Aasen, P. Olsson | PDF Free Download.
Nuclear reactors play a key role in 21st Century energy production. This new book provides critical research in both fission and fusion energy production as well as the technology of the reactors.
The role of nuclear data in Accelerator Driven Systems in order to reduce the cost for reaching a certain level of safety is presented and a detailed discussion of turbulent mixing and void drift that includes state-of-the-art models is given.
The motivation for the construction of the fusion reactors, including the laser fusion facilities and other related problems, is addressed. A brief history of magnetic confinement fusion power plant conceptual designs, focusing on tokamaks, is outlined in this book.
Furthermore, the progress and state-of-the-art of principal aspects of fusion safety and environment are discussed. Since a high quality of vacuum integrity is required in large tokamak machines, leak detection systems are overviewed and a reasonable leak detection strategy is proposed.
One of the outstanding new developments in the field of Partitioning and Transmutation (P&T) concerns Accelerator-Driven Systems (ADS), discussed in Chapter 1, which consists of a combination of a high-power, high-energy accelerator, a spallation target for neutron production, and a sub-critical reactor core.
The development of the commercial critical reactors of today motivated a large effort on nuclear data up to about 20 MeV, and presently several million data points can be found in various data libraries. Accelerator-driven transmutation will make use of neutrons up to GeV energies.
Although only a minor fraction of the neutrons will have such high energies, they nevertheless need to be well characterized. At these high energies, data are scarce or even non-existent.
The nuclear data needed for transmutation in ADS can roughly be divided into two main areas. First, the initial proton beam produces neutrons via spallation reactions.
This means that data on proton-induced neutron production is needed. In addition, data on other reactions are needed to assess the residual radioactivity of the target.
Second, the produced neutrons can induce a wide range of nuclear reactions, and knowledge of these is useful in the design of ADS. In most cases, direct data determination is not the ultimate goal. The global capacity for such measurements is insufficient to obtain complete coverage of important data.
It is even impossible in theory to supply all relevant data. This means that the experimental work must be focused on providing benchmark data for theory development, making it possible to use theoretical models for unmeasured parameters in a core environment.
In this respect, accelerator-driven systems are not fundamentally different than critical reactors. An often overlooked aspect is why nuclear data should be measured in the first place. Nuclear data are not needed for a demonstration of the principle of driving a sub-critical assembly with an external neutron source.
The need for nuclear data becomes imminent when a realistic large-scale facility is a goal. With large uncertainties in the nuclear data, large safety margins have to be used, which results in excessive costs.
Thus, the role of nuclear data is to reduce the cost of reaching a certain level of safety. Another important aspect is the trade-off between general and particular information. Below 20 MeV, a single cross-section can be of paramount importance to the entire application.
Moreover, some cross-sections are fundamentally inaccessible to theory, in particular in the resonance region.
As a result, at low energies, more or less complete data coverage for major elements is required. Above 20MeV, the situation is fundamentally different.
The cross-sections are smooth, and the behavior of the total technical system is always dictated by the sum of a large number of reactions, neither of which strongly dominates the performance. Therefore, getting a grip on the overall picture is more important than precision data on a single reaction.
If the boiling flow through fuel assemblies in a reactor core is to be predicted numerically by means of a sub-channel code, two important lateral exchange processes between neighboring sub-channels have to be taken into account: turbulent mixing and void drift.
Whereas mixing is a kind of turbulent gradient diffusion occurring in both single-phase and two-phase flow, void drift is a two-phase phenomenon that is physically not yet well understood.
However, there are a lot of phenomenological attempts to model this superimposed effect, which can act in the same direction as turbulent mixing, but also contrarily depending on sub-channel geometries and flow conditions.
Chapter 2 will classify the physical background of both phenomena including a detailed overview of the flow conditions which have to be existent in order to cause the one or other phenomenon. Furthermore, it will provide a well-structured thread through the whole calculation methodology.
Thereby, every single phenomenon will be discussed in detail (physically and mathematically) and an overview of both the particular state-of-the-art models and new approaches in open literature will be given.
In the introduction of Chapter 3, we present the motivation for the construction of the fusion reactors including the laser fusion facilities. Then, we consider the solution of the Dirac equation with the periodic potential which is called the Volkov solution.
The one-photon and two-photon Compton processes follow from this solution. The energy-momentum equation for the multi-photon process is also involved.
In the following section, we solve the problem of the interaction of an electron with the Dirac delta-form impulsive force, which is an idealization of the experimental situation in laser physics.
We elaborate on the quantum theory of the interaction of a charged particle with such impulsive force. We determine the modified Compton formula for the final frequency of photons generated by the scattering of the delta-form laser pulse on the electron in a rest.
The one-photon Compton process is only a special case of the multi-photon interaction of the electron with N photons of the laser pulse.
The multi-photon interaction is nonlinear and differs from the situation where electron scatters twice or more as it traverses the laser focus. The next problem of laser physics is the electron interaction with the two electromagnetic waves.
This is also the future direction of the laser physics of elementary particles. The two laser beams can be used in the thermonuclear reactor instead of many laser beams. In the following text, we consider the solution with massive photons in the laser beam.
The mass of the photon is of the dynamical origin corresponding to the radiative corrections. We determine the equation corresponding to the Dirac equation with the periodic potential of massive photons. The resulting equation is the Riccati equation which cannot be solved in general. So, we derive only some approximative formulas.
While massless photon is described by theMaxwell Lagrangian, the massive photon is described by the Proca Lagrangian from which the field equations follow. The massive electrodynamics can be considered as a generalization of massless electrodynamics.
Massive photons are substantial in the theory of superconductivity, plasma physics, waveguides and so on. The massive photons can be produced in very strong magnetic pulses generated by the Kapitza gigantic solenoid method, or, by the Terletzkii method of the cumulation of the magnetic flux.
It means that the deuterium-tritium pellet in the laser ignition facility can be compressed by the massive photons generated simultaneously with the magnetic delta-form pulses. The presence of the magnetic field in which the pellet can be situated leads to the generation of the synchrotron radiation of charged particles.
Motivated by this fact, we derive the synchrotron radiation formulas using the Volkov solution of the Dirac equation and the S-matrix formalism of QED for an electron moving in the constant magnetic field.
As explained in Chapter 4, the Advanced Fuel Cycle Initiative is responsible for the development of advanced nuclear energy systems. One of these nuclear energy systems is the Sodium Fast Reactor (SFR).
To maximize the performance of this type of nuclear reactor, it will be important to improve on the performance of the nuclear fuel, i.e., allow for higher fuel burnup and/or operation of the fuel at higher reactor operating temperatures.
One type of nuclear fuel currently being evaluated is a metallic U-Pu-Zr alloy, and one phenomenon that could limit the ability of the fuel to perform at temperatures that are higher than what has been typically employed is the chemical compatibility of the fuel and cladding.
During irradiation, the fuel swells and eventually contacts the cladding, at which time fuel cladding chemical interaction (FCCI) can occur.
During this process, interdiffusion occurs between the fuel, cladding, and fission products, which can result in the formation of interaction zones on the inner surface of the cladding that can become brittle or may contain relatively low-melting phases.
The result of this process can be cracking and failure of the cladding. Minimal detailed information on FCCI in irradiated metallic SFR fuels is available in the literature.
Thus, in order to facilitate an increased understanding of FCCI, this chapter describes results that have been generated from the destructive examinations of individual fuel elements that were irradiated in the Experimental Breeder Reactor-II over the course of a thirty-year timeframe.
This chapter particularly focuses on any interaction zones that developed on the inner surface of the cladding. Three examination techniques were employed to characterize FCCI in these fuel elements: optical metallography, electron probe micro-analysis, and scanning electron microscopy.
The results of these examinations were evaluated and compared to provide information about FCCI and what effects it could have on fuel performance.
Fuel elements that included U-Zr or U-Pu-Zr alloy fuels and HT-9, D9, or Type 316 stainless steel cladding were assessed.
The irradiation conditions, cladding type, and axial location on fuel elements, where the thickest layers could be expected to develop, were identified, and it was found that the largest interaction zones developed at the combined high-power and high-temperature regions of the fuel elements and for the fuel elements with U-Pu- Zr alloy fuel and D9 stainless steel cladding.
The most prevalent, non-cladding constituent observed in the developed interaction layers were the lanthanide fission products. Microalloying technology is widely used in the steel industry to improve the mechanical properties of structural steels, in which the strength and toughness are improved by the refinement of ferrite grain size.
Chapter 5 explains the importance of microalloying elements in controlling the microstructures and properties of quenched and tempered (QT) RPV steels. First, we give a brief description of the physical metallurgy of prior austenite grain refinement in microalloyed steels.
The critical microalloying element for prior austenite grain size control is shown to be titanium, which forms carbonitrides, able to pin prior austenite grain boundaries during heat treatment.
Secondly, attention is drawn to experimental results from the literature that demonstrate prior austenite grain coarsening in simulated coarse-grained heat-affected-zones (CGHAZs) in certain grades of non-microalloyed RPV steel.
Finally, we discuss the microstructures and mechanical properties of simulated heat-affected-zones (HAZs) in A508 and A533 steels.
Chapter 6 provides a brief history of magnetic confinement fusion power plant conceptual designs, beginning with the early development in 1970, focusing on tokamaks. In addition, the evolution of six more magnetic concepts (stellarator, spherical tori, field reversed configurations, reversed-field pinches, spheromaks, and tandem mirrors) is highlighted.
The key issues encountered are discussed, including the technological obstacles and the elements necessary for economic competitiveness. Extensive R&D programs and international collaboration in all areas of fusion research led to a wealth of information generated and analyzed.
As a result, fusion promises to be a major part of the energy mix in the 21st century and beyond. In Chapter 7, higher power LH wave (1.5MW) is injected into the diverted plasma with a slightly asymmetric spectrum.
Dominant electron heating and current profile control are investigated with numerical simulation. Plasma heating by electron Landau interaction results in operation scenarios of preferentially dominant electron heating.
Due to the off-axis driven current, an optimized q-profile is formed, and an enhanced confinement regime with a steep electron temperature gradient is produced. The clear decrease of the electron thermal conductivity in the LH power deposition region shows that an electron-ITB is developed.
The establishment of the current profile like in the hybrid scenario is studied under the condition of dominant electron heating in HL-2A.
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