Showing papers by "Japan Atomic Energy Research Institute published in 1988"
TL;DR: In this paper, a reduced activation ferritic steel, 8Cr-2W-0.04Ta-Fe, was aged at 673-923 K. for up to 36 Ms, and Charpy impact tests and metallurgical investigation were conducted on the aged specimens.
87 citations
TL;DR: The scale effects of a flow path under countercurrent flow limitation (CCFL) in a horizontal tube connected to an inclined riser have been studied in this article, where an analytical model with a two-fluid model was developed based on flow observation results in small scale experiments and then assessed with various scale experiments under various pressures.
80 citations
TL;DR: In this paper, the authors measured the thermal diffusivity, specific heat capacity, and density of mixtures of alkaline carbonate salts, as well as measured these properties using an adiabatic scanning calorimeter.
Abstract: The purpose of this study is to develop measuring methods for the thermal diffusivity, the specific heat capacity, and the density of molten salts, as well as to measure these properties of mixtures of alkaline carbonate salts. The thermal diffusivity is measured by the stepwise heating method. The sample salt is poured into a thin container, and as a result, a three-layered cell is formed. The thermal diffusivity is obtained from the ratio of temperature rises at different times measured at the rear surface of the cell when the front surface is heated by the stepwise energy from an iodine lamp. The specific heat capacity is measured using an adiabatic scanning calorimeter. The density is measured by Archimedes' principle. Thermal conductivity is determined from the above properties. Measured samples are Li2CO3-K2CO3 (42.7–57.3, 50.0-50.0, and 62.0-38.0 mol%).
80 citations
TL;DR: In this paper, a novel amidoxime-group-containing adsorbent of hollow-fiber form (AO-H fiber) was prepared by radiation-induced graft polymerization of acrylonitrile onto a polyethylene hollow fiber, followed by chemical conversion of the produced cyano group to an amidoxideime group.
Abstract: A novel amidoxime-group-containing adsorbent of hollow-fiber form (AO-H fiber) was prepared by radiation-induced graft polymerization of acrylonitrile onto a polyethylene hollow fiber, followed by chemical conversion of the produced cyano group to an amidoxime group. Distribution of the amidoxime group was uniform throughout the hollow-fiber membrane. The fixed-bed adsorption column, 30 cm in length and charged with the bundle of AO-H fibers, was found to adsorb uranium from natural seawater at a sufficiently high rate: 0.66 mg uranium per g of adsorbent in 25 days.
68 citations
TL;DR: In this article, it was found that the swelling behavior of a titanium-modified stainless steel (PCA) in both the cold-worked and solution-annealed conditions differed significantly from the behavior observed in earlier experiments in which the He/dpa ratio was either ~ 0.5 or ~ 50.
58 citations
TL;DR: In this paper, an interpolation of buildup factors for an arbitrary elemental material is examined using geometric-progression (G-P) parameters for an equivalent atomic number for a specific energy above KAPPA edges and penetration distance vary smoothly with respect to atomic number.
Abstract: The values of buildup factors for a specific energy above KAPPA edges and penetration distance vary smoothly with respect to atomic number. An interpolation of buildup factors for an arbitrary elemental material is examined using geometric-progression (G-P) parameters for an equivalent atomic number. The G-P parameters are data fitted to the proposed American National Standard Buildup factor data compilation of 17 elements from beryllium to molybdenum and are calculated by the moments method.
58 citations
TL;DR: In this article, natural circulation experiments were conducted in a large-scale (scale in volume) full-height simulator of a Westinghouse-type pressurized water reactor with two steam generators.
Abstract: Natural circulation experiments were conducted in a large-scale ( scale in volume) full-height simulator of a Westinghouse-type pressurized water reactor. This facility has two steam generators eac...
56 citations
TL;DR: The physicochemical form of airborne 131I, released during the Chernobyl accident, was investigated in Japan during the period 6 to 19 May 1986, and the proportions of 131I species identified during that period were: 19% particulate iodine, 5% I2, 6% HOI and 70% organic iodides as mentioned in this paper.
54 citations
TL;DR: The overall HTO(g) release rates of Li2O, γ-LiAlO2, Li2SiO3 and Li2ZrO3 were controlled by the diffusion of tritium in the crystals, while solid surface reactions competed in the release process.
51 citations
TL;DR: In this article, a two-dimensional time dependent fluid code has been developed for transport processes in the edge plasma of a tokamak, coupled with a Monte Carlo method for neutral gas behaviour.
Abstract: A two-dimensional time dependent fluid code has been developed for transport processes in the edge plasma of a tokamak, coupled with a Monte Carlo method for neutral gas behaviour. The code employs a particle-incell method for the numerical solution of fluid equations. A simulation of the Doublet III divertor experiment has been performed with this code. It has been confirmed that the radial profiles of temperature and density in the scrape-off and divertor region can be simulated fairly well
45 citations
TL;DR: In this article, a theoretical and experimental study was conducted to understand two-phase flow discharged from a stratified twophase region through a small break, and the theoretical results showed that a break quality is a function of h/hb, where h is the elevation difference between a bulk water level in the upstream region and the break and b the suffix for entrainment initiation.
Abstract: A theoretical and experimental study was conducted to understand two-phase flow discharged from a stratified two-phase region through a small break. This problem is important for an analysis of a small break loss-of-coolant accident (LOCA) in a light water reactor (LWR). The present theoretical results show that a break quality is a function of h/hb , where h is the elevation difference between a bulk water level in the upstream region and the break and b the suffix for entrainment initiation. This result is consistent with existing experimental results in literature. An air-water experiment was also conducted changing a break orientation as an experimental parameter to develop and assess the model. Comparisons between the model and the experimental results show that the present model can satisfactorily predict the flow rate and the quality at the break without using any adjusting constant when liquid entrainment occurs in a stratified two-phase region. When gas entrainment occurs, the experimental data a...
TL;DR: In this article, the silicon carbide coating layers were examined by density measurement, X-ray diffractometry, and optical and scanning electron microscopy in order to clarify the relation between deposition conditions and structure of the coating layers.
Abstract: The silicon carbide coating layers prepared under various conditions were examined by density measurement, X-ray diffractometry, and optical and scanning electron microscopies in order to clarify the relation between deposition conditions and structure of the coating layers. It was found that the deposition temperature was the main parameter affecting the content of free silicon, density, crystallite size and lattice distortion, and microstructure. The dependence of these properties on the coating rate and the composition of fluidizing gas was not observed clearly. Free silicon was co-deposited withβ-SiC at temperatures lower than 1400 to 1500° C, and the content of free silicon increased with decreasing deposition temperature. The density of the layers without free silicon was more than 3.210 Mg m−3 and the density decreased with increasing content of free silicon. Crystallite size increased with deposition temperature and lattice distortion decreased with increasing deposition temperature. The outer surfaces of the layers without free silicon consisted of large interlocked grains, whereas those of the layers with free silicon showed a cauliflower-like structure of which the apparent grain size was small.
TL;DR: In this article, a unified description of quadropole-octupole collective states in even-even nuclei in terms of an s-p-d-f boson model is presented.
TL;DR: In this article, a process based on hydrogen isotope purification through palladium/silver alloy permeators combined with selective catalytic reaction steps is proposed, which avoids intermediate conversion of impurities into water.
Abstract: For the plasma exhaust clean-up of a fusion reactor a process concept based on the hydrogen isotope purification through palladium/silver alloy permeators combined with selective catalytic reaction steps is proposed, which avoids intermediate conversion of impurities into water. To recover tritium from tritiated impurities ammonia is decomposed into the elements inside the permeators; water is reduced catalytically by carbon monoxide into carbon dioxide and hydrogen; and hydrocarbons are cracked into carbon and hydrogen on a nickel catalyst. Experimental results on the reactivity, consumption and regeneration of the catalysts are given. The permeation rate of hydrogen through palladium/silver alloy was found to be largely independent of the impurities CO, CO/sub 2/, H/sub 2/O and CH/sub 4/. Technological requirements in view of NET are discussed.
TL;DR: In this paper, the divertor characteristics in particle and energy control in neutral beam (NB) heated discharges on JT-60 have been studied with injection powers of up to 20 MW.
Abstract: The divertor characteristics in particle and energy control in neutral beam (NB) heated discharges on JT-60 have been studied with injection powers of up to 20 MW. The essential divertor functions are achieved successfully. In ohmically heated discharges, the minimum clearances between the separatrix magnetic surface and the fixed limiter for sufficient divertor action are 1.5 cm for e = 1.5 × 1019 m−3 and 2.5 to 3 cm for e = 4 × 1019 m−3. Global power balance studies show that, in NB heated divertor discharges, about 5% to 10% of the total absorbed power, PABS, is radiated from the main plasma, while 50% to 60% is radiated in the limiter discharge. For e = 6 × 1019 m−3, 50% of PABS flows to the divertor plate. The radiation loss in the divertor chamber is 15% of PABS. According to the spatial distribution of the temperature rise on the divertor plate, the half-width of the heat load is less than 1 cm for e = 1.5 to 4.4 × 1019 m−3. The neutral pressures in the divertor chamber and around the main plasma increase in proportion to e2. The compression ratio is about 45. The effectiveness of the divertor pumping system in particle control is demonstrated for NB pulses of, at least, 1 s. Reduction of evaporation by separatrix swing is also shown.
TL;DR: In this article, the copolymerization of l-lactic acid (LA) and δ-valerolactone (VL) was performed in the presence of water without catalysts at 200° under nitrogen.
TL;DR: In this paper, the tritium release behavior in both materials appeared to be governed by both diffusion and surface adsorption-desorption mechanisms, and a model including both mechanisms was developed to analyze the data from this experiment.
TL;DR: In this article, the authors examined the structural properties of PCA's after irradiation at temperatures of 400°C and below and showed that the mutual stability of the radiation enhanced MC precipitation, and fine bubbles associated with such precipitation, contributed to the extension of the transient regime of swelling to fluences above 34 dpa.
TL;DR: A realistic torso phantom with average body size of Japanese adult males has been developed for the calibration of counting systems used for in-vivo measurements of plutonium and other actinides.
Abstract: A realistic torso phantom with average body size of Japanese adult males has been developed for the calibration of counting systems used for in-vivo measurements of plutonium and other actinides. The phantom contains removable model organs (lungs, liver, kidneys and heart), model trachea and artificial rib cage, and also includes chest plates that can be placed over the chest to simulate wide range adipose/muscle ratio in the human chest. Tissue substitutes used in the phantom were made of polyurethane with different concentrations of ester of phosphoric acid. Model lungs were made of foamed polyurethane with small quantities of the additive, and the artificial rib cage was made of epoxy resin with calcium carbonate. The experimental data have shown that the phantom can be used as a standard phantom for the calibration.
TL;DR: In this paper, a system of in-situ observation during ion irradiation and implantation was constructed by combining an electron microscope with an ion beam, where the mass analyzed ion beam is introduced into the electron microscope in the horizontal direction and deflected by a large angle of 72° inside the specimen chamber so as to be incident nearly normally to the specimen surface maintained at temperatures up to 1350°C.
TL;DR: In this paper, the chemical state of solid fission products (FPs) was studied using simulated spent fuels of 5-30% FIMA, which were made by the heat-treatment at 1273 to 2273 K under various oxygen potentials.
TL;DR: In this paper, a model was developed to describe ion driven permeation when gas-driven permeation coexists, and the results were analyzed with a model which was developed for describing ion driven and gas driven coexisting.
TL;DR: In this article, the transient boiling heat transfer characteristics of R113 at large stepwise power generation are investigated experimentally over a wide range of system pressures, and the experimental results are summarized as follows.
TL;DR: In this paper, the crystal structure of La/sub 6/UO/sub 12/ was studied by the X-ray powder diffraction technique, and the crystal system was known to rhombohedral atoms.
TL;DR: In this article, a mechanism of radiation-induced degradation of a polymer matrix composite was proposed to explain the dose dependence of the composite strength measured at 77 K and at room temperature.
Abstract: Four kinds of polymer matrix composites (filler, E-glass or carbon fibre cloth; matrix, epoxy or polyimide resin) and pure epoxy and polyimide resins were irradiated with 60Co γ-rays or 2 MeV electrons at room temperature. Mechanical tests were then carried out at 77 K and at room temperature. Following irradiation, the Young's (tensile) modulus of these composites and pure resins remains practically unchanged even at 170 MGy for both test temperatures. The ultimate strength, however, decreases appreciably with increasing dose. The dose dependence of the composite strength depends not only on the combination of fibre and matrix in the composite but also on the test temperature. A relationship is found between the composite ultimate strain and the matrix ultimate strain, thus indicating that the dose dependence of the composite strength is virtually determined by a change in the matrix ultimate strain due to irradiation. Based on this finding, we propose a mechanism of radiation-induced degradation of a polymer matrix composite in order to explain the dose dependence of the composite strength measured at 77 K and at room temperature.
TL;DR: In this paper, the authors measured hydrogen and deuterium concentrations in aluminum at 600°C in the pressure range from 0.2 to 1.0 atm, by means of a desorption technique which was an outgassing study from thermally gas-charged cylindrical samples with various amounts of voids.
TL;DR: In this paper, the Woodley equation for the oxygen potential of the plutonium-uranium solid solution was shown to be well-expressed by the thermodynamic data for the solid solutions M y U 1−y O 2+x ( x x ⩾ 0) were reviewed for Pu, Ce, La and Gd.
TL;DR: In this article, an experimentally altered (1−14 days, deionized water, 90°C) synthetic borosilicate glass and naturally altered (10 4 years, fresh water, 0−100°C), basalt glass were characterized by analytical electron microscopy to evaluate the development of alteration layers.
Abstract: An experimentally altered (1–14 days, deionized water, 90°C), synthetic borosilicate glass and naturally altered (10 4 years, fresh water, 0–100°C), basalt glass were characterized by analytical electron microscopy to evaluate the development of alteration layers. Layers formed on borosilicate glass are initially amorphous. With increasing age, nontronite, chlorite, septechlorite, and/or stilpnomelane appear to precipitate and grow within the amorphous matrix and on the surface of the layer. Crystals are enriched in Fe, Co, and Ni, and depleted in Si relative to the surrounding amorphous matrix. Alteration layers on basalt glass are texturally and mineralogically similar to layers formed on borosilicate glass, but the degree of crystallinity is less.
TL;DR: In this article, the authors studied the effect of H2O2 on the extraction rate and the enhancement of the extraction speed of Np with di-isodecyl phosphoric acid (DIDPA).
Abstract: Extraction of Np with di-isodecyl phosphoric acid (DIDPA) from HN03 solution containing H2O2> was studied from the aspect of the extraction mechanism and the enhancement of the extraction rate. Neptunium initially in the pentavalent oxidation state can be extracted into DIDPA even without any redox agents, but the extraction rate is rather slow. In the present work, H2O2 was found to accelerate the extraction. The rate was almost proportional to the 1/2-power of H2O2 concentration. Dependence of the extraction rate on HN03 concentration was also examined. Neptunium extracted into DIDPA from 0.5 M HN03 solution containing H2O2 was found to be in the tetravalent state in the organic phase, whereas neptunium in aqueous phase was in the pentavalent state. Reduction of Np(V) with H2O2 occurs rapidly in the presence of DIDPA. When the concentration of HNO3 was 4 M. the neptunium extracted was also tetravalent, but the reduction of NP(V) in an aqueous solution was also observed.