Takeshi Suwa

FTIR reflection absorption spectroscopy for organic thin film on ITO substrate

Abstract Dielectric constant of indium–tin oxide (ITO) substrate was obtained by the basis of free electron model to evaluate the reflection infrared (IR) spectrum of an organic thin film on the ITO substrate in the wavenumber region from 3500 to 600 cm−1. In a wavenumber region of less than 2000 cm−1, the given spectrum was approximate to the spectrum on a metal substrate having high reflectivity. In this region, the thickness of the PVCz thin film under physical vapor deposition process was proportional to the peak intensity of reflection spectrum.

Development of chemical decontamination process with sulfuric acid-cerium(IV) for decommissioning. Single step process to dissolve chromium-rich oxides

The dissolution of Cr-rich oxides in and the decontamination of contaminated specimens by sulfuric acid-Ce(IV) (SC) solution have been investigated. The results have been com-pared with those by the reported typical decontamination reagents. The SC solution can dissolve simultaneously not only Cr but also Fe and Ni in the Cr-rich oxides. The dissolution mainly depends on Ce(IV) concentration (1.3–10−3 M) and temperature (40–90°C), but is independent of H2SO4-concentration (0.2–0.5 M at 5 x 10−3M Ce(IV)). The DF is ca. 33 at 90°C for 24 h with 0.25 M H2SO4-5 x 10−3M Ce(IV). Under electrolytic regeneration of Ce(IV) from Ce(III) during the decontamination, the DF is raised to 460 even at 80°C for 24 h with 0.25 M H2SO4-1.3 x 10−3M Ce(IV). The SC solution can be applicable to the decontamination for decommissioning of both BWR and PWR. Fcrthermore the combination of the chemical cleaning with an additional ultrasonic cleaning provides a promissing cleaning procedure for post-disassembly components.

Development of Chemical Decontamination Process with Sulfuric Acid-Cerium (IV)for Decommissioning: System Decontamination Process with Electrolytic Regeneration of Ce4+ from Ce3+

The electrolytic regeneration of Ce4+ from Ce3+, which is required to achieve a high decontamination factor (DF) in this process, has been investigated. A calculating model was derived for the regenerating current required during the decontamination as a function of dissolution rate of crud, corrosion rate (Rc ), current efficiency (ηe ) and characteristics of decontamination loop. From the above calculation, it was found that the current was mainly governed by Rc and ηe . A condition to obtain a high DF at low Rc and high ηe has been found experimentally by use of a mixture of Ce3+ and Ce4+ at the ratio of Ce4+/Ce3+=0.1∼0.2. The desired values to be ηe ≧80% at above 50 A/m2 was obtained under the flow rate above 300 cm/min and Ce3+ concentration above 10x10−3M at 60°C using the dual-cylindrical type cell. The current efficiency was also investigated with cells of various geometries. The present decontamination process has been proposed as a system decontamination process, which is essentially a single-st...

Volume phase transition induced by temperature sensitive DL-amino acid methyl ester side chain based copolymer gels

Polymer gels based on methacryloyl-DL-amino acid methyl esters with different alkyl groups on the α-carbon (MA-DL-AA-OMe) were synthesized to evaluate the apparent lower critical solution temperature (LCST) from the composition-induced volume phase transition behavior of their copolymer gels as a function of the temperature. Methacryloyl-DL-alanine methyl ester (MA-DL-AlaOMe) gel showed a thermo-responsive volume phase transition around 22°C, which is close to its LCST of 25°C. In contrast with this, methacryloyl-DL-amino acid methyl ester (MA-DL-AAOMe) gels with alkyl groups on the α-carbon larger than ethyl (Et) collapsed without a volume phase transition. Based on an extrapolated linear plot between the volume phase transition temperatures (VPTTs) estimated using data from the composition-induced volume phase transition at a given temperature and composition for the copolymer gels MA-DL-AlaOMe/MA-DL-AbuOMe and MA-DL-AlaOMe/methacryloyl-norvaline methyl ester (MA-DL-nValOMe), the apparent LCST was estimated to be 22°C for MA-DL-AlaOMe, -35°C for MA-DL-AbuOMe, and -58°C for MA-DL-nValOMe.

Crud Behaviors in High Temperature Water, (II): Characterization of Corrosion Layer on Type 304 Stainless Steel and Zircaloy-2

Sample specimens of type 304 stainless steel and Zircaloy-2 were exposed to the OWL-1 loop water at 280°C for 23d. After the exposure, a number of crystallites are distributed either separately or sometimes in agglomerate on the surfaces. The X-ray diffraction analysis and XMA analysis of the type 304 stainless steel surface revealed that more than 95% of the crystallites have a M2O3-type of structure, and some are enriched in Cr. In the sub-sequent radiochemical analysis of the fractions detached by the various cleaning processes (ultrasonic, electrostripping and electropolishing), it is noticed that the 60Co/Co ratio decreases with the depth of the corrosion layer from the value close to that of insoluble crud in the water (crud-P) to that of soluble crud (crud-F).