Challenges for enhancing Fukushima environmental resilience, 4; Development of physical and heat treatment methods on aiming at decontamination, volume reduction and reuse of contaminated soil

Yaita, Tsuyoshi; Honda, Mitsunori; Shimoyama, Iwao; Ito, Kenichi*; Mampuku, Yuzo*; Tsuji, Takuya; Matsumura, Daiju

Nihon Genshiryoku Gakkai-Shi ATOMO, 59(8), p.483 - 487, 2017/08

no abstracts in English

A Time-of-flight neutron imaging detector using ZnS/LiF scintillator and wavelength shifting fibers with high spatial resolution and with low gamma-ray sensitivity

Nakamura, Tatsuya; To, Kentaro; Kawasaki, Takuro; Honda, Katsunori; Birumachi, Atsushi; Ebine, Masumi; Sakasai, Kaoru; Soyama, Kazuhiko; Katagiri, Masaki*

Proceedings of 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference; 21st International Symposium on Room-Temperature Semiconductor X-ray and -ray detectors (NSS/MIC 2014), p.1751 - 1753, 2014/00

https://doi.org/10.1109/NSSMIC.2014.7431170

The ZnS scintillator-based two-dimensional detector was developed for a time-of-flight neutron imaging with a high spatial resolution and a low -ray sensitivity. The detector is comprised of a thin ZnS scintillator with crossed wavelength-shifting-fibers (WLS fibers) arrays equipped with the fiber optic taper (FOT). The developed detector based on a neutron counting method has a high spatial resolution of less than 100 um (in FWHM) with a moderate count rate capability of several tens of thousands of cps. Of particular interest is its low -ray sensitivity of 10. Imaging capabilities of the detector are demonstrated by using a high-intensity pulsed neutron beam at the Materials and Life Science Experimental Facility in the Japan Proton Accelerator Complex (J-PARC/MLF).

Isolation and characterization of alkaliphilic nitrate-reducing bacteria from soil

Murakami, Hiroshi; Kato, Takashi*; Honda, Akira

Nihon Mizu Shori Seibutsu Gakkai-Shi, 44(4), p.217 - 223, 2008/12

http://ci.nii.ac.jp/naid/10023991183

Chemical transition of nitrate ions accompanied with corrosion of carbon steel under alkaline conditions

Honda, Akira; Kato, Takashi; Tateishi, Tsuyoshi*; Imakita, Tsuyoshi*; Masuda, Kaoru*; Kato, Osamu*; Nishimura, Tsutomu*

Zairyo To Kankyo, 55(10), p.458 - 465, 2006/10

https://doi.org/10.3323/jcorr.55.458

Migration of radioactive material can be affected by the redox condition and the concentration of ligands in the repository of radioactive waste. It is possible that radioactive waste contains nitrate which can affect the migration behavior of radioactive nuclides by both changing the redox condition of the environment and acting as a ligand. On the other hand, several researchers observed the reduction of nitrate ions in ammonia due to the iron. Ammonia has a potential to ligand for radioactive nuclides. Nitrate can also affect the rate of hydrogen gas evolution accompanied by metal corrosion through changing the rest potential of metal by its oxidizing nature. Carbon steel was, therefore, immersed in an aqueous solution of sodium nitrate in a closed system for observing both the chemical interaction between metal and nitrate, and the effect of nitrate on the hydrogen gas evolution rate. The experimental pH range of the solution was 10.0-13.5 which corresponds to the pH range of pore fluid of cementitious material. The cathodic current density shows a Tafel equation type potential dependency in the aqueous solution containing nitrate or nitrite. In spite of the acceleration of cathodic reaction due to the existence of nitrate, the corrosion rates of carbon steel were not accelerated in the nitrate solutions. This fact suggests that the system is controlled by the anodic reaction. The nitrate reduction accompanied by the corrosion of carbon steel is considered to be a series reaction such as nitrate nitrite ammonia. The nitrate reduction reaction compete with the water reduction reaction within the anodic controlled condition, therefore nitrate strongly reduced the hydrogen evolution rate. The generation rates of ammonia were independent of the concentration of nitrate.

An Estimation of the chemical evolution of nitrate due to the metal corrosion and microbiological reaction.

Masuda, Kaoru*; Kato, Takashi; Honda, Akira

JNC TN8400 2005-021, 19 Pages, 2005/09

JNC-TN8400-2005-021.pdf:0.74MB

Uranium and Plutonium are planed to be recovered from spent fuel by the reprocessing in Japan. PUREX method is internationally dominant among the commercial reprocessing plants. PUREX method has been also employed in Japan. The low level liquid waste from PUREX process would contain NO as forms of soluble salts, if the special process for decomposing NO were not adopted. The nitrate is possibly brought within the repository for TRU waste. The generation of H gas and the reduction of NO due to metal corrosion and the generation of N gas due to the microbiological reactions in repository for group3 waste were estimated. The uncertainty on the hydraulic conductivity of cementitious materials, corrosion rates, and microbiological reactions are reflected to the analyses through setting the multiple cases. The analysis results suggested followings. (1) The maximum concentrations of both NO and NH were given in the case where the hydraulic conductivity of cementitious material was assumed to be low ( 5.010 m/s) and the corrosion rate was constant at the initial value (0.1 um/y). (2) The maximum concentration of NH was estimated to be 0.8 mol/dm. (3) The impact of microbiological reaction (denitrifying reaction) was negligible in terms of yield of NO and NH because the proportion of denitrified NO was low. (4) The existence of NO was strongly reduced the evolution of H gas because the nitrate reduction and nitrite reduction dominate the cathodic reactions. (5) The N gas evolution rate due to the denitrifying reaction by microorganisms dominated the total gas evolution rate, if time dependent reduction of corrosion rate was employed. However, the H gas evolution rate in the case is similar to those of N gas due to the denitrifying reaction mentioned above, if time dependent reduction of corrosion rate was neglected

X-ray CT analysis on archaeological iron based artifacts

Honda, Takashi*; Gunji, Eiichi*

JNC TJ8400 2004-030, 38 Pages, 2005/01

JNC-TJ8400-2004-030.pdf:4.05MB

Corrosion analysis was carried out on twenty iron-plates, which had been dug out at the 6th Yamato ancient tomb (Nara-shi). It was evaluated through the inner-structural analysis by X-ray CT and the XRD and chemical analysis of the rusts that the most iron-plates had been buried in a slightly oxidizing environment and the maximum corrosion depth was 1.6 mm for about 1500 years. The analysis result of the extreme-value data indicates that the maximum depth of an overpack is estimated to be 2.5-2.6 mm. A part of small iron-plates were supposed to have been buried in an oxidizing environment, and about 1 mm-thick rust layers with cavities existed and the corrosion amount was figured out to be about 0.3 mm.

Improvement of beam performance in the negative-ion based NBI system for JT-60U

Umeda, Naotaka; Grisham, L. R.*; Yamamoto, Takumi; Kuriyama, Masaaki; Kawai, Mikito; Oga, Tokumichi; Mogaki, Kazuhiko; Akino, Noboru; Yamazaki, Haruyuki*; Usui, Katsutomi; et al.

Nuclear Fusion, 43(7), p.522 - 526, 2003/07

https://doi.org/10.1088/0029-5515/43/7/302

The Negative-ion based Neutral Beam Injection System (N-NBI) for JT-60U has been operating for plasma heating and non-inductive current drive since 1996. The target is inject of neutral beam into plasma with beam energy 500 keV, injection power 10 MW, for 10 seconds. Until now pulse duration time was restricted up to 5.3 seconds because of larger heat load of port limiter. Recently from the measurement of beam profile at 3.5m downstream from the ion source, it was found that the outermost beamlets in each segment were deflected outward. It was caused by non-uniform electric field by grooves. By improving this, outermost beamlet deflection angle was decreased from 14 mrad to 4 mrad. In this result, 10 seconds injection, which is target parameter, has achieved at 355 keV, 2.6MW, while pulse length was restricted up to 5.3 seconds by larger heat load of port limiter.

Analysis of the Excavated Archaeological Iron Using X-ray-CT as Natural Analogue

Yoshikawa, Hideki; Ueno, Kenichi; ; Honda, Takashi*; *

9th International Conference on Environmental Remediation Ra, 0 Pages, 2003/00

None

Inspection about the corrosion of metallic archaeological artifacts in ground (II)

Honda, Takashi*; *

JNC TJ8400 2001-045, 102 Pages, 2002/02

JNC-TJ8400-2001-045.pdf:7.65MB

The corrosion of iron-base archaeological artifacts, which were dug out in Iyomai-7 (Chitose-shi, Hokkaido) and Izumo-Ooyashiro-Keidai (Taisha-machi, Shimane-ken) sites, was investigated by using X-ray CT, XRD, atomic absorption spectroscopy and EDX techniques. While the artifacts such as swords in Iyomai-7 site had been buried in the ground for 400-500 years, metallic iron remained in the swords and the corrosion amounts were estimated to be 2-5mm. Several artifacts were investigated among a lot of iron rings and nails buried beside huge pillars of the ancient shrine. Those artifacts had been in ground for 730-750 years. The corrosion amounts were estimated to be 3-5mm. As the both soil environments are supposed to be oxidizing, the outer oxide layers of all speicies are composed of goethite and soil. Further, it was clarified that perfectly corroded ones had hollow structures. In this study, the sampling method of species, the corrosion environmental factors, and the corrosion kinetic models were also evaluated.

Inspection about the corrosion of metallic archaeological artifacts in ground

Honda, Takashi*; *

JNC TJ8400 2000-007, 200 Pages, 2000/02

JNC-TJ8400-2000-007.pdf:14.84MB

In general, it is very difficult to evaluate the residual state of metallic iron and the original shape of iron-base archaeological artifacts, as these are covered by thick oxide films formed in the ground during over several hundred years. The purpose of this research is to quantify the corrosion of an artifact such as base, knife, and nail, which was digged out of the relics about 500-1,000 years old. (1)The outer oxide film layer and the inner metallic iron can be quantitatively divided by using X-ray CT method. Furthermore, the original surfaces of artifacts can be estimated from the obtained images, even if the metallic iron has corroded completely. The X-ray CT images were also compared with those obtained by X-ray transmission inspection. (2)The corrosion amounts and rates were evaluated on the basis of thicknesses, densities, and iron concentrations of oxide films. (3)The characteristic differences between ancient iron and modern carbon steel were evaluated by analyzing the ancient iron slag.