A demonstration study on a closed-cycle hydrogen production by the thermochemical water-splitting iodine–sulfur process

Chemical vapor deposition (CVD) is an important technique for surface modification of powders through either grafting or deposition of films and coatings. The efficiency of this complex process primarily depends on appropriate contact between the reactive gas phase and the solid particles to be treated. Based on this requirement, the first part of this review focuses on the ways to ensure such contact and particularly on the formation of fluidized beds. Combination of constraints due to both fluidization and chemical vapor deposition leads to the definition of different types of reactors as an alternative to classical fluidized beds, such as spouted beds, circulating beds operating in turbulent and fast-transport regimes or vibro-fluidized beds. They operate under thermal but also plasma activation of the reactive gas and their design mainly depends on the type of powders to be treated. Modeling of both reactors and operating conditions is a valuable tool for understanding and optimizing these complex processes and materials. In the second part of the review, the state of the art on materials produced by fluidized bed chemical vapor deposition is presented. Beyond pioneering applications in the nuclear power industry, application domains, such as heterogeneous catalysis, microelectronics, photovoltaics and protection against wear, oxidation and heat are potentially concerned by processes involving chemical vapor deposition on powders. Moreover, simple and reduced cost FBCVD processes where the material to coat is immersed in the FB, allow the production of coatings for metals with different wear, oxidation and corrosion resistance. Finally, large-scale production of advanced nanomaterials is a promising area for the future extension and development of this technique.

https://oatao.univ-toulouse.fr/649/1/Vahlas_649.pdf

Principles and applications of CVD powder technology

X-ray phase-contrast imaging and tomography make use of the refraction of X-rays by the sample in image formation. This provides considerable additional information in the image compared to conventional X-ray imaging methods, which rely solely on X-ray absorption by the sample. Phase-contrast imaging highlights edges and internal boundaries of a sample and is thus complementary to absorption contrast, which is more sensitive to the bulk of the sample. Phase-contrast can also be used to image low-density materials, which do not absorb X-rays sufficiently to form a conventional X-ray image. In the context of materials science, X-ray phase-contrast imaging and tomography have particular value in the 2D and 3D characterization of low-density materials, the detection of cracks and voids and the analysis of composites and multiphase materials where the different components have similar X-ray attenuation coefficients. Here we review the use of phase-contrast imaging and tomography for a wide variety of materials science characterization problems using both synchrotron and laboratory sources and further demonstrate the particular benefits of phase contrast in the laboratory setting with a series of case studies.

In-Line Phase-Contrast X-ray Imaging and Tomography for Materials Science

Nuclear heat for hydrogen production: Coupling a very high/high temperature reactor to a hydrogen production plant

Liquid-fluoride-salt heat transfer fluids are proposed to raise the heat-to-electricity efficiencies of solar power towers to about 50%. The liquid salt would deliver heat from the solar furnace at temperatures between 700°C and 850°C to a closed multireheat Brayton power cycle using nitrogen or helium as the working fluid. During the daytime, hot salt may also be used to heat graphite, which would then be used as a heat storage medium to make night-time operations possible. Graphite is a low-cost high-heat-capacity solid that is chemically compatible with liquid fluoride salts at high temperatures. About half the cost of a solar power tower is associated with the mirrors that focus light on the receiver, and less than one-third is associated with the power cycle and heat storage. Consequently, increasing the efficiency by 20–30% has the potential for major reductions in the cost of electricity. Peak temperatures and efficiencies of current designs of power towers are restricted by (1) the use of liquid nitrate salts that decompose at high temperatures and (2) steam cycles in which corrosion limits peak temperature. The liquid-fluoride-salt technology and closed Brayton power cycles are being developed for high-temperature nuclear reactors. These developments may provide the technology and industrial basis for an advanced solar power tower.

/pdf/high-temperature-liquid-fluoride-salt-closed-brayton-cycle-5bf2rote3c.pdf

High-Temperature Liquid-Fluoride-Salt Closed-Brayton-Cycle Solar Power Towers

Overview of HTTR design features

GTHTR300 design and development

The coated particle fuel has been developed within a framework of the HTTR (High Temperature engineering Test Reactor) Development Program at the Japan Atomic Energy Research Institute. The HTTR fuel is a prismatic block type containing TRISO-coated U02 particles. Research and development on the fuel has been progressed in three categories; a work for fuel production technology, a proof test of fuel performance and a safety-related research. In the present report the concept and outline of the fuel in the HTTR design are firstly described, and then fuel fabrication technology including recently developed methods for improving fuel quality is followed. Tests for proving fuel performance have been carried out extensively on the reference fuel of the HTTR design by irradiation in an in-pile gas loop and capsules, and typical results are presented in this report. Concerning the safety-related research, fuel failure and 137Cs release at abnormally high temperature are described.

/pdf/research-and-development-of-httr-coated-particle-fuel-1nuxzhuoar.pdf

Research and Development of HTTR Coated Particle Fuel

Safety criteria and quality control of HTTR fuel

The High Temperature Engineering Test Reactor (HTTR). which is the first high temperature gas-cooled reactor (HTGR) in Japan, attained its first criticality in November 1998. The fabrication of the...

Shusaku Shiozawa

Papers

Overview of HTTR design features

GTHTR300 design and development

Research and Development of HTTR Coated Particle Fuel

Safety criteria and quality control of HTTR fuel

Fabrication of the First-Loading Fuel of the High Temperature Engineering Test Reactor