LOCA steam condensation loads in BWR Mark II pressure suppression containment system

Hydrodynamic loads induced in the BWR Mark II pressure suppression containment system during a loss-of-coolant accident (LOCA) were investigated using a large scale test facility. The maximum-bounding loading conditions on the pressure suppression pool-boundary structures were defined by conducting experiments for a wide range of parameters. The maximum-bounding loads occurred when steam, with air concentration less than 1% in weight, was injected at moderate rates ( 30 kg/m²·s) into a low-temperature (below 310 K) pool. Such conditions are most likely to be encountered during LOCAs with intermediate break sizes.     

Glial tumourettes (glial microtumours): their clinical and histopathological manifestations

This study represents our experience with eight cases (males: 4; females: 4; 13-47 years old, average age 28.5 years) of a "glial tumourette" (minute glioma), which measured less than 15 mm in diameter on an MRI. Four tumours were located in the frontal lobe, one in the rostrum of the corpus callosum, two in the midbrain, and one in the thalamus. The symptoms and signs lasted from two days to 15 months prior to diagnosis, and they consisted of epileptic seizures in five patients and increased intracranial pressure due to hydrocephalus resulting from aqueductal stenosis in three. All patients had a CT scan and an MRI as a part of their initial neuroimaging evaluations. While the CT findings failed to show the lesion in four patients, MRI demonstrated it in all cases. Five tumours were either totally or subtotally removed while the remaining three were biopsied. Histological examinations revealed six tumours to be low-grade gliomas (fibrillary astrocytoma: 4; oligoastrocytoma: 2) and two to be high-grade gliomas (anaplastic astrocytoma: 1; anaplastic oligodendroglioma: 1). Regarding adjuvant therapy, three patients received radiation and/or chemotherapy. One of the patients with midbrain fibrillary astrocytoma died of the disease 38 months after the operation, however, no evidence of progression in the remaining seven has been observed in the follow-up period ranging from five to 65 months after the operation (average: 25.4 months). The histogenesis of benign and malignant gliomas and the importance of surgical exploration in the management of such patients with minute intracerebral tumours are also discussed.     

Carbonization properties of hydrogenated aromatic hydrocarbons—III: Modifying activities of hydrogenated pryene and its oxidized derivatives in the co-carbonization of coals and coal liquids

The modifying activities of hydrogenated pyrene (HP) and its oxidized derivatives were examined in co-carbonization with solvent refined coal, solvent treated coal, a fusible and a non-fusible coal. The present additives all showed a significant activity, with HP oxidized at 150°C exhibiting the highest activity. The activity of the additive is discussed from its structural indices and coke yield in relation to its dissolving and hydrogen donating abilities. The modifying susceptivility of the carbonizing substance is rated in the order described above, being correlated with its single carbonization properties, such as fusibility and potential for anisotropic development. A consecutive treatment of partial hydrogenation and oxidation is emphasized as a useful technique for producing active additive and an excellent coking substance from the pitch material.     

Carbonization of pitch: Compatibility of components in carbonization

The carbonization of four kinds of solvent-refined-coal (SRC) pitches was investigated in order to determine the properties required for the formation of needle coke. Although the pitches were free from Ql materials, two of them gave needle cokes, whereas the other two gave mosaic cokes. The BS fractions of all pitches formed needle cokes, and all Bl fractions were infusible and isotropic. A combination of suitable BS and Bl fractions gave a needle coke, whereas another mixture formed a mosaic coke, indicating that the BS and the Bl fractions can be compatible to yield a needle coke. Cocarbonization of the BS fractions from other pitch sources with the Bl from the SRC pitches was further studied to evaluate the compatibility, which has been discussed from the structural viewpoint. Trials to improve the properties were proposed, based on the structural information.     

Low viscosity COM (coal oil mixture) using tall-oil as an additive

Tall oil, an inexpensive by-product from pulp manufacturing (about one-tenth of the cost to those of ordinary surfactants), was found as an effective additive for COM (coal oil mixture) to provide good stability and low viscosity. The viscosity of COM (coal concentration: 50%) was as low as 2 Pa at 70 °C after 25 day-storage by addition of only 1% of tall-oil to COM. Tall-oil supported an increase in concentration of coal from 46% to 52.5%, maintaining usable viscosity. Structural viscosity (SV) of COM was proposed by the authors and defined as follows: SV = η(2.2)−η(22); where η(2.2) and η(22) are the viscosities at low shear rate (2.2 s⁻¹) and high shear rate (22 s⁻¹), respectively. The SV was found to be a good parameter for predicting the sedimentation stability and the viscosity of COM after long-term storage in the case of Miike-COM.     

Multi-staging for extraction of cesium from nitric acid by a single liquid–liquid countercurrent centrifugal extractor with Taylor vortices

Fission products that emit considerable decay heat and radioactivity, such as ¹³⁷Cs, have a large impact on waste management. Small and high-performance extractor is desirable for separating such nuclei. In this study, we implemented the continuous extraction of Cs from nitric acid in a single liquid–liquid countercurrent centrifugal extractor with Taylor Vortices by calix[4]arene-bis(t-octylbenzo-crown-6)(BOBCalixC6) as an extractant with trioctylamine(TOA) as a suppressant and with 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) as a phase modifier. Because of slow extraction kinetics of this process, extraction with multiple theoretical stages by just replacing conventional extractors into the single centrifugal extractor is difficult. Hence, we improved the dispersion of organic phase by an inner rotor made of lipophilic epoxy resin and elevating the solution temperature to lower the viscosity. Higher temperature was not appropriate from the aspect of chemical equilibrium in this process, but extraction with multiple theoretical stages was found to be possible.     

Quantification of styrene–butadiene rubber swelling as a function of the toluene content in gasoline: A new method to detect adulterations of fuels

The swelling of styrene–butadiene rubber (SBR) when exposed to organic solvents was measured and mathematically correlated to the toluene concentration in a complex mixture such as gasoline. This relation enables inferences to be made regarding the composition and quality criteria of the fuel and represents a new method to detect adulterations. Changes in the mass and volume were measured by gravimetric and hydrostatic techniques. A simplex‐lattice experimental mixture design was carried out in mixtures with toluene, heptane, and type C gasoline (a blend of gasoline with ethanol) and the mass swelling was statically analyzed for 5 and 15 min of continuous immersion in the mixtures of the solvents. For the experimental design two cubic equations were obtained with a high value for R²‐ajusted (>0.98) at 25°C ± 1°C correlating mass swelling of SBR and the content of solvents. For both immersion times, the greatest and most important effect over the mass swelling was the content of toluene, with the mass variations increasing proportionally with toluene content in the gasoline. The analysis of variance applied to the mass swelling data verified that it is possible to obtain good mathematical equations to associate the rubber swelling with the solvent composition and concentration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

EXTRACTION OF METAL-OXALATE COMPLEXES BY DICATIONIC ANION-EXCHANGE EXTRACTANTS

The extraction of oxalate complexes of divalent metal ions (Zn²⁺, Cd²⁺ ) by dicationic anion-exchange extractants, polymethylenebis(trioctylphosphonium)s (abbreviated as C_nBP), was studied. The shorter the length of methylene-chain connecting two cationic centers within an extractant molecule, the higher was the extractant capability, i. e., the extraction ability of extractants decreased in the order: C₂- > C₃- > C₄- > C₅- > C₆- > C₈- > C₁₀- > C₁₂BP. The entirely inverse order was obtained in the extraction of metal-halide complexes (M^IICl₄ ²-) and metal-cyanide complexes (M II(CN) ₄ ²-). The extraction abilities of monocationic extractants were inferior to even that of the least efficient one among the dicationic extractants. The extraction equilibrium was also studied.     

Recovery of Tritium from Wastewater Generated by Decommissioning of Gas Cooled Reactors (GCR)

The recovery of tritium from wastewater generated by the decommissioning of a 166‐MWe GCR, Tokai‐1, nuclear reactor was evaluated. The dimensions of two tritium separation columns, water distillation process and hydrogen‐isotope exchange with hydrophobic Pt‐catalyst, were evaluated numerically under the assumptions that the recovery of tritium from the wastewater would be completed in five years and the wastewater after the recovery of tritium would be suitable for release into the environment. It was found that, in addition to lower steam, the column was smaller than that for the water distillation process. The hydrogen‐isotope exchange process was suitable for the treatment of wastewater, not only for a process design point of view but also for a reduction of energy consumption.