Regulator halts assembly of fusion reactor Clery, Daniel
Science (American Association for the Advancement of Science),
2022-Mar-04, 2022-03-04, 20220304, Volume:
375, Issue:
6584
Journal Article
Peer reviewed
ITER must meet safety concerns before welding giant tokamak sections.
Over the last two decades, flow technologies have become increasingly popular in the field of organic chemistry, offering solutions for engineering and/or chemical problems. Flow reactors enhance the ...mass and heat transfer, resulting in rapid reaction mixing, and enable a precise control over the reaction parameters, increasing the overall process selectivity, efficiency and safety. These features allow chemists to tackle unexploited challenges in their work, with the ultimate objective making chemistry more accessible for laboratory and industrial applications, avoiding the need to store and handle toxic, reactive and explosive reagents. This review covers some of the latest and most relevant developments in the field of continuous flow chemistry with the focus on hazardous reactions.
Flow chemistry allows chemists to tackle unexploited challenges, with the ultimate objective making chemistry more accessible for laboratory and industrial applications, avoiding the need to store and handle toxic, reactive and explosive reagents. This review covers the latest and most relevant developments in the field of continuous flow chemistry.
Continuous-flow liquid phase oxidation chemistry in microreactors receives a lot of attention as the reactor provides enhanced heat and mass transfer characteristics, safe use of hazardous oxidants, ...high interfacial areas, and scale-up potential. In this review, an up-to-date overview of both technological and chemical aspects of liquid phase oxidation chemistry in continuous-flow microreactors is given. A description of mass and heat transfer phenomena is provided and fundamental principles are deduced which can be used to make a judicious choice for a suitable reactor. In addition, the safety aspects of continuous-flow technology are discussed. Next, oxidation chemistry in flow is discussed, including the use of oxygen, hydrogen peroxide, ozone and other oxidants in flow. Finally, the scale-up potential for continuous-flow reactors is described.
This review gives an exhaustive overview of the engineering principles, safety aspects and chemistry associated with liquid phase oxidation in continuous-flow microreactors.
Nuclear safety is a key component of the national security system, and it is the foundation and lifeline of the nuclear industry. Advanced and reliable nuclear safety technology is crucial for ...maintaining and improving intrinsic safety. Therefore, conducting strategic research on nuclear safety technologies is important for enhancing the nuclear industry in China. In this article, we conduct an in-depth research on China’s nuclear safety technology system using methods including academician interviews, field surveys, conference discussion, and literature review. The results show that, guiding by the overall national security and the nuclear safety concepts, China’s nuclear safety technology has made significant progress in recent years and its nuclear safety performance is good. However, China’s nuclear safety technology system still face several bottleneck problems. For example, the nuclear safety standards system needs improvement, the overall planning of nuclear safety software research and development is
The quest for controlled fusion energy has been ongoing for over a half century. The demonstration of ignition and energy gain from thermonuclear fuels in the laboratory has been a major goal of ...fusion research for decades. Thermonuclear ignition is widely considered a milestone in the development of fusion energy, as well as a major scientic achievement with important applications in national security and basic sciences. The US is arguably the world leader in the inertial connement approach to fusion and has invested in large facilities to pursue it, with the objective of establishing the science related to the safety and reliability of the stockpile of nuclear weapons. Although signicant progress has been made in recent years, major challenges still remain in the quest for thermonuclear ignition via laser fusion. Here, we review the current state of the art in inertial connement fusion research and describe the underlying physical principles.
The motivation for transitioning away from zirconium-based fuel cladding in light water reactors to significantly more oxidation-resistant materials, thereby enhancing safety margins during severe ...accidents, is laid out. A review of the development status for three accident tolerant fuel cladding technologies, namely coated zirconium-based cladding, ferritic alumina-forming alloy cladding, and silicon carbide fiber–reinforced silicon carbide matrix composite cladding, is offered. Technical challenges and data gaps for each of these cladding technologies are highlighted. Full development towards commercial deployment of these technologies is identified as a high priority for the nuclear industry.
The synthesis of complex organic compounds is largely a manual process that is often incompletely documented. To address these shortcomings, we developed an abstraction that maps commonly reported ...methodological instructions into discrete steps amenable to automation. These unit operations were implemented in a modular robotic platform by using a chemical programming language that formalizes and controls the assembly of the molecules. We validated the concept by directing the automated system to synthesize three pharmaceutical compounds, diphenhydramine hydrochloride, rufinamide, and sildenafil, without any human intervention. Yields and purities of products and intermediates were comparable to or better than those achieved manually. The syntheses are captured as digital code that can be published, versioned, and transferred flexibly between platforms with no modification, thereby greatly enhancing reproducibility and reliable access to complex molecules.
•A review on numerical modelling of nuclear flashing flows is provided.•Consideration of interphase slip with a two-fluid model is often necessary.•Thermal, velocity and pressure effects all affect ...the vaporization rate.•Poly-disperse models considering different interfacial topologies are promising.
The flashing flow is a relevant multiphase phenomenon in many technical applications including nuclear safety analysis, which has been the subject of intense research for several decades. Numerical studies have evolved from one-dimensional to multi-dimensional. A variety of methods has been proposed, while a broad consensus does not exist yet. The present work aims to present an overview of available models and assess their limitations and perspectives by conducting an extensive literature survey. The final focus was put on recent progresses of computational fluid dynamics simulations. Some consensus on modelling interfacial slip, phase change mechanism and bubble size is identified. Since flashing scenarios often accompanying with high void fraction and broad bubble size range, a poly-disperse two-fluid model is recommended. Thermal phase change model is superior to pressure phase change, relaxation and equilibrium models for practical flashing problems, however incorporation of pressure effects is desirable. Major challenges comprise improving closure models for interphase transfer, bubble dynamics processes, interfacial area as well two-phase turbulence. For this purpose, high-resolution high quality experimental data are important, which are lacking in many cases. Considering that heterogeneous gas structures often exist in flashing flows, multi-field approaches able to handle different shapes of gas-liquid interface and including the shape effect in closure models are recommended for further study.
Lithium metal anodes offer high theoretical capacities (3,860 milliampere-hours per gram)
, but rechargeable batteries built with such anodes suffer from dendrite growth and low Coulombic efficiency ...(the ratio of charge output to charge input), preventing their commercial adoption
. The formation of inactive ('dead') lithium- which consists of both (electro)chemically formed Li
compounds in the solid electrolyte interphase and electrically isolated unreacted metallic Li
(refs
)-causes capacity loss and safety hazards. Quantitatively distinguishing between Li
in components of the solid electrolyte interphase and unreacted metallic Li
has not been possible, owing to the lack of effective diagnostic tools. Optical microscopy
, in situ environmental transmission electron microscopy
, X-ray microtomography
and magnetic resonance imaging
provide a morphological perspective with little chemical information. Nuclear magnetic resonance
, X-ray photoelectron spectroscopy
and cryogenic transmission electron microscopy
can distinguish between Li
in the solid electrolyte interphase and metallic Li
, but their detection ranges are limited to surfaces or local regions. Here we establish the analytical method of titration gas chromatography to quantify the contribution of unreacted metallic Li
to the total amount of inactive lithium. We identify the unreacted metallic Li
, not the (electro)chemically formed Li
in the solid electrolyte interphase, as the dominant source of inactive lithium and capacity loss. By coupling the unreacted metallic Li
content to observations of its local microstructure and nanostructure by cryogenic electron microscopy (both scanning and transmission), we also establish the formation mechanism of inactive lithium in different types of electrolytes and determine the underlying cause of low Coulombic efficiency in plating and stripping (the charge and discharge processes, respectively, in a full cell) of lithium metal anodes. We propose strategies for making lithium plating and stripping more efficient so that lithium metal anodes can be used for next-generation high-energy batteries.
Abstract Against the background of the rapid development of nuclear energy and nuclear technology, the number of places with radioactivity has gradually risen, which poses a significant safety hazard ...to human beings. Aiming at indoor radioactive places, this paper designs a detector that can be mounted on a robot, and experiments prove that this detector can accurately detect α-surface contamination and β-surface contamination. The surface contamination is measured using a combination of a remote-controlled robot and a detector.
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