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Journal Articles

Genetic survey of indigenous microbial eukaryotic communities, mainly fungi, in sedimentary rock matrices of deep terrestrial subsurface

Saito, Yoshimoto*; Hirano, Shinichi*; Nagaoka, Toru*; Amano, Yuki

Ecological Genetics and Genomics, 12, p.100042_1 - 100042_9, 2019/10

Culture-independent molecular techniques enable us to analyze microflora in various environments. Many uncultured prokaryotes have been detected by the molecular methods from extreme environments, including anaerobic, no light, high-pressure, and high temperature. Recently, microbial eukaryotes were also detected in deep-sea environments, suggesting that microbial eukaryotes can adapt to a wider range of environments than previously thought. Here, we performed a culture-independent analysis of eukaryotes from approximately -250 m depth in the Horonobe Underground Research Laboratory at Horonobe, Japan. Our results indicate that fungi are the dominant eukaryotic flora in deep sedimentary rocks of Horonobe. We detected a wide range of species, including Zygomycete, Basidiomycete, and Ascomycete fungi from the rocks. This study is the first report of eukaryotic diversity in deep subsurface sedimentary rocks.

Journal Articles

Carbon steel corrosion induced by microbial community in soil environment and its analysis

Hirano, Shinichi*; Nagaoka, Toru*; Ise, Kotaro; Amano, Yuki; Matsumoto, Norio*

Zairyo To Kankyo, 64(12), p.535 - 539, 2015/12

To obtain the knowledge about the corrosion ability and its mechanism as a target the soil environment microorganisms, lake mud was cultured with metallic iron. As a result, corrosion of carbon steel was observed with sulfate reduction and methane producing activity in brackish medium with lactate as substrate. Inhibition test of SRB and MPA suggested that SRB plays a major role for this corrosion, and MPA enhanced corrosion activity by the coexistence of SRB.

Journal Articles

Simplified risk assessment based on accident categories at Tokai Reprocessing Plant

Nagaoka, Shinichi; Ishida, Michihiko; Kanamori, Sadamu; Hayashi, Shinichiro

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

The feasibility of applying PSA to nuclear fuel cycle facilities such as reprocessing plants has been also studied. We conducted a simplified risk assessment of each of the selected individual accident events and compared the assessment results for four accident categories (fire, explosion, criticality, and other accident events in which large amounts of radioactive materials are released).

Journal Articles

A Study to control chemical reactions using Si:2p core ionization; Site-specific fragmentation

Nagaoka, Shinichi*; Fukuzawa, Hironobu*; Pr$"u$mper, G.*; Takemoto, Mai*; Takahashi, Osamu*; Yamaguchi, Takuhiro*; Kakiuchi, Takuhiro*; Tabayashi, Kiyohiko*; Suzuki, Isao*; Harries, J.; et al.

Journal of Physical Chemistry A, 115(32), p.8822 - 8831, 2011/07

 Times Cited Count:29 Percentile:71.09(Chemistry, Physical)

Journal Articles

Study on loss detection algorithms using tank monitoring data

Suzuki, Mitsutoshi; Hori, Masato; Nagaoka, Shinichi; Kimura, Takashi

Journal of Nuclear Science and Technology, 46(2), p.184 - 192, 2009/02

 Times Cited Count:11 Percentile:59.85(Nuclear Science & Technology)

An application of solution monitoring to material balance has been investigated with an actual data of the Solution Monitoring Management System (SMMS) in the Tokai Reprocessing Plant (TRP). Loss detection capabilities of the proposed multivariate statistical methods are examined numerically for a simulated loss corresponding to parameters of a significant quantity in the wait mode. Multi-scale statistical analysis as well as multivariate cumulative sum analysis are successfully used to demonstrate the protracted-loss detection. Since the actual tank data is composed of both records in the wait and the transfer mode, the tank-to-tank transferring data is extracted from the sequence of monitoring data and the effectiveness of error model is evaluated in comparison with calculations. Although the data taken from the SMMS does not describe in the entire solution process, an extended application of solution monitoring to the nuclear material accounting is advanced using the plant data.

Oral presentation

Study of neptunium behavior in extraction process of Tokai reprocessing plant, 1; Results on balance of neptunium in extraction process

Nagaoka, Shinichi; Morimoto, Kazuyuki; Sato, Takehiko; Kanamori, Sadamu; Omori, Eiichi

no journal, , 

no abstracts in English

Oral presentation

Investigations and test plan for neptunium recovery in Tokai reprocessing plant

Nagaoka, Shinichi; Kawaguchi, Yoshihito

no journal, , 

In Tokai Reprocessing Plant (TRP), 50$$sim$$60% of Np is transferred to waste. To co-recover Pu-U-Np, the large ratio of Np transition to waste is problem. So we are investigating Np behavior with extraction cycles in TRP to obtain control technology for Pu-U-Np co-recovery. Now we present Np behavior in TRP and plan of research co-recovery of Pu-U-Np.

Oral presentation

MOX reprocessing at Tokai reprocessing plant

Taguchi, Katsuya; Nagaoka, Shinichi; Yamanaka, Atsushi; Sato, Takehiko; Nakamura, Yoshinobu; Omori, Eiichi; Miura, Nobuyuki

no journal, , 

no abstracts in English

Oral presentation

MOX reprocessing at TRP, 4; Control test of Neptunium extraction

Kawakami, Yoshiyuki; Nagaoka, Shinichi; Kitao, Takahiko; Morimoto, Kazuyuki; Obu, Tomoyuki; Kanamori, Sadamu; Omori, Eiichi

no journal, , 

We are trying to research how acidity and temperature influences Np behavior at extraction process in Tokai Reprocessing Plant. So we varied acidity and warmed up solution within the limit of operating parameter for second extraction cycle, and measured Np extracted.

Oral presentation

Application of multi-scale statistical process control method to tank monitoring data

Suzuki, Mitsutoshi; Hori, Masato; Nagaoka, Shinichi; Kimura, Takashi

no journal, , 

In order to develop an advanced data evaluation algorithm of Solution Monitoring Management System (SMMS) in a nuclear reprocessing plant, we have applied a multi-scale statistical process control method using a wavelet decomposition to LDT (Level, Density and Temperature) tank data and evaluated an effectiveness of the method. We will present the evaluation results.

Oral presentation

Control test of neptunium extraction at Tokai reprocessing plant

Nagaoka, Shinichi; Morimoto, Kazuyuki; Kitao, Takahiko; Obu, Tomoyuki; Kanamori, Sadamu; Omori, Eiichi

no journal, , 

40$$sim$$50% of neptunium (Np) was distributed to product stream in Tokai Reprocessing Plant (TRP) at present. We tried to increase acidity of second extraction cycle within available operating parameter, and by measuring neptunium concentration at outlet stage in second extraction cycle, we verified that 60$$sim$$70% of neptunium was distributed to product stream. Also we warmed up solutions in contactors of second extraction cycle within available operating parameter to make sure oxidation of neptunium on actual process, and we verified that 70% of neptunium was distributed to product stream. We confirmed that increasing acidity and warming up solutions was effective for Pu-U-Np co-extraction on the engineering scale reprocessing facility.

Oral presentation

Control test of Neptunium extraction at TRP

Nagaoka, Shinichi

no journal, , 

We are trying to research how acidity and temperature influences Np behavior at extraction process in Tokai Reprocessing Plant. So we varied acidity and warmed up solution within the limit of operating parameter for second extraction cycle, and measured Np extracted.

Oral presentation

Simplified risk assessment of individual accident event for Tokai Reprocessing Plant

Nagaoka, Shinichi; Taguchi, Katsuya; Ishida, Michihiko; Kanamori, Sadamu

no journal, , 

no abstracts in English

Oral presentation

Tests of uranium partitioning behavior in U and Pu co-recovery process

Kudo, Atsunari; Nagaoka, Shinichi; Yanagibashi, Futoshi

no journal, , 

no abstracts in English

Oral presentation

Microbiological considerations relevant to a deep geological repository; Research review and perspective

Nagaoka, Toru*; Hirano, Shinichi*; Matsumoto, Norio*; Amano, Yuki; Ise, Kotaro; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Oral presentation

Emergency safety measures at the Tokai Reprocessing, 2

Ouchi, Masayuki; Hoshi, Takahiro; Sasaki, Shunichi; Isobe, Hiroyasu; Nagaoka, Shinichi; Kurabayashi, Kazuaki; Obu, Tomoyuki

no journal, , 

Plutonium nitrate solution is stored in tanks that have cooling system to prevent boiling accident by decay heat and scavenging system to prevent explosion of hydrogen generated by radiolysis. These systems are designed to be provided power from emergency power generators at the Tokai Reprocessing Plant (TRP) when commercial power is lost. In addition, some apparatus (mobile power generators and nitrogen gas cylinder to scavenge hydrogen, etc.) are recently deployed at TRP on the basis of power loss in Fukushima Daiichi nuclear accident. In this report, these safety measures for emergency are shown.

Oral presentation

Hafnium adsorption on clean Si(110)16$$times$$2 single domain surface studied by low energy electron diffraction and electron spectroscopy

Kakiuchi, Takuhiro*; Katsuragi, Takuma*; Nakano, Yuji*; Yoshigoe, Akitaka; Nagaoka, Shinichi*; Mase, Kazuhiko*

no journal, , 

HfO$$_{2}$$ has been becoming important as a future dielectric material for future metal-oxide-semiconductor devices. In this study, surface structure, surface chemical state, and valence electronic structure after oxidation of single domain Si(110)-16$$times$$2 surface have precisely measured by using low-energy-electron diffraction and synchrotron radiation photroemission spectroscopy. It was found that five possible adsorption sites (SC1-SC5) of the single domain Si(110)-16$$times$$2 surface are uniformely reacted with Hf atoms with increasing its exposure, indicating that random Hf adsorption takes place on the surface.

Oral presentation

Measurement of the hydrogen concentration in the vessel off-gas generated radiolytically from Pu storage tanks

Hoshi, Takahiro; Nagaoka, Shinichi; Kudo, Atsunari; Ouchi, Masayuki; Isobe, Hiroyasu; Obu, Tomoyuki; Kurabayashi, Kazuaki

no journal, , 

no abstracts in English

Oral presentation

Development of U and Pu co-recovery in Tokai Reprocessing Plant; Development of reprocessing process in Operation Testing Laboratory in TRP

Kudo, Atsunari; Nagaoka, Shinichi; Kurabayashi, Kazuaki; Yanagibashi, Futoshi; Obu, Tomoyuki

no journal, , 

no abstracts in English

26 (Records 1-20 displayed on this page)