The Global Energy Assessment (GEA) brings together over 300 international researchers to provide an independent, scientifically based, integrated and policy-relevant analysis of current and emerging energy issues and options. It has been peer-reviewed anonymously by an additional 200 international experts. The GEA assesses the major global challenges for sustainable development and their linkages to energy; the technologies and resources available for providing energy services; future energy systems that address the major challenges; and the policies and other measures that are needed to realize transformational change toward sustainable energy futures. The GEA goes beyond existing studies on energy issues by presenting a comprehensive and integrated analysis of energy chalenges, opportunities and strategies, for developing, industrialized and emerging economies. This volume is a invaluable resource for energy specialists and technologists in all sectors (academia, industry and government) as well as policymakers, development economists and practitioners in international organizations and national governments.

Global Energy Assessment: Toward a Sustainable Future

More than 1000× uranium exists in the oceans than exists in terrestrial ores. With nuclear power generation expected to increase over the coming decades, access to this unconventional reserve is a matter of energy security. With origins in the mid-1950s, materials have been developed for the selective recovery of seawater uranium for more than six decades, with a renewed interest in particular since 2010. This review comprehensively surveys materials developed from 2000–2016 for recovery of seawater uranium, in particular including recent developments in inorganic materials; polymer adsorbents and related research pertaining to amidoxime; and nanostructured materials such as metal–organic frameworks, porous-organic polymers, and mesoporous carbons. Challenges of performing reliable and reproducible uranium adsorption studies are also discussed, as well as the standardization of parameters necessary to ensure valid comparisons between different adsorbents.

Materials for the Recovery of Uranium from Seawater

Ionizing radiation has been found to be widely applicable in modifying the structure and properties of polymers, and can be used to tailor the performance of either bulk materials or surfaces. Fifty years of research in polymer radiation chemistry has led to numerous applications of commercial and economic importance, and work remains active in the application of radiation to practical uses involving polymeric materials. This paper provides a survey of radiation-processing methods of industrial interest, ranging from technologies already commercially well established, through innovations in the active R&D stage which show exceptional promise for future commercial use. Radiation-processing technologies are discussed under the following categories: cross-linking of plastics and rubbers, curing of coatings and inks, heat-shrink products, fiber–matrix composites, chain-scission for processing control, surface modification, grafting, hydrogels, sterilization, natural product enhancement, plastics recycling, ceramic precursors, electronic property materials, ion-track membranes and lithography for microdevice production. In addition to new technological innovations utilizing conventional gamma and e-beam sources, a number of promising new applications make use of novel radiation types which include ion beams (heavy ions, light ions, highly focused microscopic beams and high-intensity pulses), soft X-rays which are focused, coherent X-rays (from a synchrotron) and e-beams which undergo scattering to generate patterns.

High-energy radiation and polymers: A review of commercial processes and emerging applications

The recovery of uranium (U) from seawater has been investigated for over six decades in efforts to secure uranium sources for future energy production. The majority of the research activities have focused on inorganic materials, chelating polymers, and nanomaterials. Previous studies of uranium adsorption from aqueous solutions, mainly seawater, are reviewed here with a focus on various adsorbent materials, adsorption parameters, adsorption characterization, and marine studies. Continuous progress has been made over several decades, with adsorbent loadings approaching 3.2 mg U/g adsorbent in equilibrium with seawater. Further research is needed to improve first, the viability including improved capacity, selectivity, and kinetics, and second, the sorbent regeneration for multicycle use. An overview of the status of the uranium adsorption technology is provided and future research needs to make this technology commercially competitive are discussed.

Recovery of Uranium from Seawater: A Review of Current Status and Future Research Needs

Radioactive cesium removal from nuclear wastewater by novel inorganic and conjugate adsorbents

The total amount of uranium dissolved in seawater at a uniform concentration of 3 mg U/m{sup 3} in the world's oceans is 4.5 billion tons. An adsorption method using polymeric adsorbents capable of specifically recovering uranium from seawater is reported to be economically feasible. A uranium-specific nonwoven fabric was used as the adsorbent packed in an adsorption cage 16 m{sup 2} in cross-sectional area and 16 cm in height. We submerged three adsorption cages in the Pacific Ocean at a depth of 20 m at 7 km offshore of Japan. The three adsorption cages consisted of stacks of 52 000 sheets of the uranium-specific non-woven fabric with a total mass of 350 kg. The total amount of uranium recovered by the nonwoven fabric was >1 kg in terms of yellow cake during a total submersion time of 240 days in the ocean.

Aquaculture of Uranium in Seawater by a Fabric-Adsorbent Submerged System

Cost Estimation of Uranium Recovery from Seawater with System of Braid Type Adsorbent Masao TAMADA1,, Noriaki SEKO1, Noboru KASAI1 and Takao SHIMIZU2 1Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki-shi, Gunma 3701292, Japan 2Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi, Chiba 2701194, Japan (Received February 21, 2006 and accepted in revised form July 20, 2006)

Cost estimation of uranium recovery from seawater with system of braid type adsorbent

SiC fibers with excellent thermal stability have been developed by means of reducing their oxygen content. Polycarbosilane fibers were cured by electron beam irradiation in a stream of helium and were pyrolized in an inert atmosphere. These SiC fibers were continuous, in multifilament form, consisting of Si-1.3C-0.02O by atomic ratio. They had a high tensile strength and elastic modulus of 2.8 GPa and 270 GPa, respectively. At high temperature, the low oxygen SiC fibers were observed to undergo no chemical decompositions and retained good tensile properties. The mechanical properties of the SiC composites reinforced by these SiC fibers were also investigated. 7 refs.

Thermal stability of the low oxygen silicon carbide fibers derived from polycarbosilane

A product having reduced friction and improved abrasion resistance comprises a formed resin containing at least one fluorine-containing polymer which is exposed to an ionizing radiation. The formed resin may include from 1 to 100 weight percent of the fluorine-containing polymer in the form of powder, and from 99 to 0 percent of a high molecule polymer which is not exposed to the ionizing radiation. The fluorine-containing polymer is preferably exposed to the ionizing radiation for a total dose of from 1 KGy to 10 MGy in the absence of oxygen at a temperature not lower than the melting point of a starting fluorine-containing polymer.

Product having reduced friction and improved abrasion resistance

We have developed a material that can be used to remove cesium (Cs) in Fukushima Prefecture and other contaminated areas. The developed material was prepared by radiation-induced graft polymerization of ammonium 12-molybdophosphate and acrylonitrile onto nonwoven polyethylene fabric. To evaluate the adsorption performance of the developed material, we conducted batch and column experiments by using a Cs solution with a concentration of 1 ppm at pH 7. In the batch study, the adsorbent was able to remove 90, 87 and 64 % of Cs from pure water, acidic water and seawater, respectively. In the column study, adsorbent packed in a column with a diameter of 7 mm and a height of 5 cm was able to remove nearly the entire amount of dissolved Cs. The solution (1 ppm Cs at pH 7) was pumped into the column at a space velocity of 300 h−1, in which the Cs adsorption capacity at the breakthrough point reached 54 g-Cs/kg-adsorbent. Adsorbent grafted into a cartridge with a diameter of 4 cm and a height of 3.8 cm was used in a field test on removing dissolved radioactive Cs in Iitate-mura, and this test was conducted successfully.

Noboru Kasai

Papers

Aquaculture of Uranium in Seawater by a Fabric-Adsorbent Submerged System

Cost estimation of uranium recovery from seawater with system of braid type adsorbent

Thermal stability of the low oxygen silicon carbide fibers derived from polycarbosilane

Product having reduced friction and improved abrasion resistance

Hybrid grafted ion exchanger for decontamination of radioactive cesium in Fukushima Prefecture and other contaminated areas