First observation of O

Kondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08

https://doi.org/10.1038/s41586-023-06352-6

no abstracts in English

Dry cleaning process test for fuel assembly of fast reactor plant system, 1; Pilot scale test for fuel pin bundle

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Ishikawa, Nobuyuki; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Ide, Akihiro*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

A next generation SFR in Japan has adopted an advanced dry cleaning system which consists of the argon gas blowing process to reduce the amount of metallic residual sodium remaining on spent fuel assemblies. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on a fuel pin bundle before and after the argon gas blowing process. The experiments were conducted using a sodium test loop and a short specimen consisting of a 7 pin bundle. The effects of the blowing gas velocity and the blowing time were quantitatively analyzed in the experiments. On the basis of these experimental results, evaluation models predicting the amount of the residual sodium were constructed.

Estimation of mitigation effects of sodium nanofluid for SGTR accidents in SFR

Ichikawa, Kenta*; Kanda, Hironori; Yoshioka, Naoki*; Ara, Kuniaki; Saito, Junichi; Nagai, Keiichi

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 6 Pages, 2018/07

Studies on the suppression of the reactivity of sodium itself have been performed on the basis of the concept of suspended nanoparticles in liquid sodium (sodium nanofluid). According to the experimental and theoretical results of studies for sodium nanofluid, velocity and heat of sodium nanofluid-water reaction are lower than those of the pure sodium-water reaction. The analytical model for the peak temperature of a sodium nanofluid-water reaction jet has been developed in consideration of these suppression effects by the authors. In this paper, the prediction method for mitigation effects for a damage of adjacent tubes in a steam generator tube rupture (SGTR) accidents is arranged by applying this analytical model for the peak temperature of the reaction jet. On the assumption that the sodium nanofluid is used for the secondary coolant of sodium-cooled fast reactor (SFR), mitigation effects under the design-base accident (DBA) condition and the design-extension condition (DEC) of SGTR are estimated by using this method. As a result, there is a possibility to reduce the number of damaged tubes and to suppress the pressure generated by SGTR accidents by using sodium nanofluid in the secondary coolant.

Measurements and evaluations of air dose rates around Fukushima, 5; Characteristics of air dose rate distribution in the environment around the Fukushima Nuclear Power Plant site

Mikami, Satoshi; Matsuda, Norihiro; Ando, Masaki; Kinase, Sakae; Kitano, Mitsuaki; Kawase, Keiichi; Matsumoto, Shinichiro; Yamamoto, Hideaki; Saito, Kimiaki

Radioisotopes, 64(9), p.589 - 607, 2015/09

https://doi.org/10.3769/radioisotopes.64.589

This article presents the features of regional distributions and temporal changes in air dose rate and radionuclide deposition densities in Fukushima on the basis of analyses on large-scale environmental monitoring results using diverse methods. The continuity of decontamination effects is discussed according to repeated monitoring data after the decontamination model project. Further, some examples are shown on the projection of air dose rates together with the ecological half lives for different land uses.

Study on the Development of Geological Environmental Model(II) -Outline-

Tsujimoto, Keiichi*; Shinohara, Yoshinori*; Saito, Shigeyuki*; Ueta, Shinzo*; Ohashi, Toyo*; Sasaki, Ryoichi*; Shingo, Tomiyama*

JNC TJ8400 2003-040, 78 Pages, 2003/02

JNC-TJ8400-2003-040.pdf:1.45MB

The safety performance assessment was carried out in imaginary geological environment in the conventional research and development of geological disposal, but the importance of safety assessment based on the repository design and considering the concrete geological environment will increase in the future. The research considering the link of the major three fields of geological disposal, investigation of geological environment, repository design and safety performance assessment, is the contemporary worldwide research theme. Hence it is important to organize information flow that contains the series if information process from the data production to analysis in the three fields, and to systemize the knowledge base that unifies the information flow hierarchically.The information flow for geological environment model generation process is examined and modified base on the product of the research of "Study on the development of geological environment model" that of the research in 2002. The work flow diagram for geological structure and hydrology are modified, and those for geochemical and rock property are examined from the search. Furthermore, database design was examined to build geochemical environment database (knowledgebase) based on the result of the systemization of the environment model generation technology. The geochemical environment database was designed and the prototype system is build to contribute database design.

Study on the development of geological environmental Model

Tsujimoto, Keiichi*; Shinohara, Yoshinori*; Saito, Shigeyuki*; Ueta, Shinzo*; *; *; *

JNC TJ8400 2002-030, 100 Pages, 2002/03

JNC-TJ8400-2002-030.pdf:0.98MB

The safety performance assessment was carried out in potential geological environment in the conventional research and development of geological disposal, but the importance of safety assessment based on the repository design and scenario considering the concrete geological environment will increase in the future. The research considering the link of the major three fields of geological disposal, investigation of geological environment, repository design, and safety performance assessment, is the contemporary worldwide research theme. Hence it is important to organize information flow that contains the series of information process form the data production to analysis in the three fields, and to systemize the knowledge base that unifies the information flow hierarchically. The purpose of the research is to support the development of the unified analysis system for geological disposal. The development technology for geological environmental model studied for the second progress report by JNC are organized and examined for the purpose of developing database system with considering the suitability for the deep underground research facility. The geological environmental investigation technology and building methodology for geological structure and hydro geological structure models are organized and systemized. Furthermore, the quality assurance methods in building geological environment models are examined. Information which is used and stored in the unified analysis system are examined to design database structure of the system based on the organized methodlogy for building geological environmental model. The graphic processing function for data stored in the unified database are examined. Furthermore, future research subjects for the development of detail models for geological disposal are surveyed to organize safety performance system.

None

Saito, Hiroshi; Kawase, Keiichi; Sugihara, Kozo;

Saikuru Kiko Giho, (7), p.93 - 98, 2000/06

https://rdreview.jaea.go.jp/gihou/pdf2/9902.PDF

None

TIARA electrostatic accelerators for multiple ion beam applications

Saito, Yuichi; Tajima, Satoshi; ; Mizuhashi, Kiyoshi; Uno, Sadanori; ; Ishii, Yasuyuki; Kamiya, Tomihiro; Yotsumoto, Keiichi; Tanaka, Ryuichi; et al.

Nuclear Instruments and Methods in Physics Research B, 89, p.23 - 26, 1994/00

https://doi.org/10.1016/0168-583X(94)95138-1

no abstracts in English

Radial dispersion of a solute in the bed packed with ion-exchange resins

; Saito, Keiichiro; Shiba, Koreyuki

J.Chem.Eng.Jpn., 17(3), p.327 - 329, 1984/00

https://doi.org/10.1252/jcej.17.327

no abstracts in English

Steady-state characteristics of lithium isotope separation by a circuit of continuous displacement chromatography

Fujine, Sachio; Saito, Keiichiro; Shiba, Koreyuki; Itoi, T.*

Sep.Sci.Technol., 17(13-14), p.1545 - 1563, 1983/00

https://doi.org/10.1080/01496398209438472

no abstracts in English