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pelletMoroi, Yuriko*; Kirishima, Akira*; Akiyama, Daisuke*; Sato, Nobuaki*; Kitamura, Akira; Kimuro, Shingo
no journal, ,
Direct disposal of spent nuclear fuel is considered as an alternative option of geological disposal of high level radioactive wastes. In this case, the dissolution speed of uranium should be one of the most important parameter. In this study, the dissolution behavior of UO in the simulated groundwater contains high concentration of carbonate ion was investigated, then, it was revealed that uranium dissolution was promoted by the carbonate ion.
Ohgama, Kazuya; Hara, Toshiharu*; Ota, Hirokazu*; Naganuma, Masayuki; Oki, Shigeo; Iizuka, Masatoshi*
no journal, ,
no abstracts in English
Toh, Yosuke; Tsuchiya, Harufumi; Ozu, Akira; Furutaka, Kazuyoshi; Kitatani, Fumito; Komeda, Masao; Maeda, Makoto; Koizumi, Mitsuo
no journal, ,
no abstracts in English
Ozu, Akira; Maeda, Makoto; Komeda, Masao; Toh, Yosuke
no journal, ,
no abstracts in English
Ishitsuka, Etsuo; Kenzhina, I.*; Okumura, Keisuke; Ho, H. Q.; Takemoto, Noriyuki; Chikhray, Y.*
no journal, ,
An increase of tritium concentration in the primary coolant for JMTR and JRR-3M revealed that the recoil tritium release from the beryllium reflector is dominant.
Endo, Yuya; Maeda, Tsuyoshi; Uezu, Yasuhiro; Lochard, J.*; Clement, C.*; Fujita, Hiroki*; Ando, Ryoko*
no journal, ,
no abstracts in English
Ho, H. Q.; Fujimoto, Nozomu*; Hamamoto, Shimpei; Ishii, Toshiaki; Nagasumi, Satoru; Ishitsuka, Etsuo
no journal, ,
Komeda, Masao; Toh, Yosuke; Ozu, Akira
no journal, ,
no abstracts in English
Malins, A.; Imamura, Naohiro*; Niizato, Tadafumi; Kim, M.; Sakuma, Kazuyuki; Shinomiya, Yoshiki*; Miura, Satoru*; Machida, Masahiko
no journal, ,
We analyzed changes in ambient dose equivalent rates (
*(10)) between 2011 and 2017 in forests in Fukushima Prefecture. PHITS was used to calculate the effects of changes in the distribution of 
Cs and 
Cs within forests on *(10). The transfer of radiocesium from the crowns of evergreen coniferous trees to the forest floor appeared to cause slower decreases in *(10) at 1 m height in early years than expected by the rate of Cs and Cs decay.
Suzuki, Seiya; Yano, Kimihiko; Okamura, Nobuo; Watanabe, Masayuki
no journal, ,
no abstracts in English
Koizumi, Mitsuo; Omer, M.; Takahashi, Tone; Seya, Michio; Hajima, Ryoichi; Shizuma, Toshiyuki; Hashimoto, Satoshi*; Amano, So*; Miyamoto, Shuji*
no journal, ,
JAEA, QST, and University of Hyogo are developing a nuclear material detection technique that utilizes a measurement method of nuclear resonance fluorescence gamma-ray scattering induced by laser Compton scattering gamma-ray beams, under the subsidiary for "promotion of strengthening nuclear security or the like" of MEXT. So far, experimental apparatus, a laser system, gamma-ray detectors, data acquisition systems, and so on, are prepared for a demonstration experiment to be performed at NEW SBARU facility of University of Hyogo. An imitated nuclear material sample hidden in a shield will be placed on an automatic stage. This presentation overview the purpose of this program, preparation status, plan of demonstration experiments and a workshop.
Takahashi, Tone; Ito, Fumiaki*; Koizumi, Mitsuo; Suzuki, Satoshi*; Yogo, Akifumi*; Arikawa, Yasunobu*; Abe, Yuki*; Hori, Junichi*; Sano, Tadafumi*; Lee, J.; et al.
no journal, ,
Some nondestructive assay (NDA) methods for validation of highly radioactive nuclear material have been developed under the subsidiary for nuclear security promotion of MEXT. Nuclear Resonance Transmission Analysis (NRTA) is able to measure the density of each isotope of fissile and quite useful for analysis of solid samples like fuel debris. However, it is not easy to install due to a large Time-of-Flight (TOF) system which is required for the precise measurement. So, we have proposed a NRTA combined with Laser Driven Neutron Source (LDNS). TOF system would be shortened less than 5 m because of extremely short pulse width of LDNS. A conceptual design of LDNS-NRTA will be presented.
Nagai, Takayuki; Sasage, Kenichi; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*
no journal, ,
no abstracts in English
Seki, Misaki; Ishikawa, Koji*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Suzuki, Yumi*; Tanaka, Atsushi*; Kawakami, Tomohiko*; Ide, Hiroshi; Tsuchiya, Kunihiko
no journal, ,
no abstracts in English
Kawaguchi, Koichi; Segawa, Tomoomi; Ishii, Katsunori; Suzuki, Akihiro*
no journal, ,
no abstracts in English
Iwatsuki, Teruki; Murakami, Hiroaki
no journal, ,
We reproduced the groundwater quality in granite up to a depth of about 1000m using the geochemical simulation code, and devised a method to identify the major minerals involved in the evolution of water quality. We also estimated the long-term water-rock interaction of these minerals based on groundwater ages.
Arisaka, Makoto; Yamagishi, Isao; Sato, Hiroyuki; Terada, Atsuhiko
no journal, ,
no abstracts in English
Yamamoto, Tomohiko; Matsubara, Shinichiro*; Iwasaki, Akihisa*; Kawamura, Kazuki*; Harada, Hidenori*
no journal, ,
A fast reactor core consists of hundreds of core elements, which lengthen due to thermal expansion and swelling. So, the core elements are self-standing on the core support structure and not restrained in the axial direction. The authors carried out vibration tests and verification of analysis code (REVIAN-3) to evaluate 3D core vibration behavior. This report describes the summary of some experimental results and analysis.
Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Higashi, Hideo*; Fukuyama, Hiroyuki*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.
no journal, ,
It is necessary to simulate a eutectic melting reaction and relocation behavior of boron carbide (B
C) as a control rod material and stainless steel (SS) during a core disruptive accident in an advanced sodium-cooled fast reactor designed in Japan. On that account, a new project has been started to conduct eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range of liquid and solid states. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress by JFY2018.
Okumura, Keisuke; Terashima, Kenichi
no journal, ,
The dose rate of fuel debris retrieved from the Fukushima Daiichi Nuclear Power Plant is necessary for radiation shielding, exposure management of workers and so on. However, it depends on many parameters of fuel debris such as size, radiation source nuclides, elemental composition, density, porosity, burnup, and evaluation time. Therefore, we have developed a dose rate prediction formula applicable to various fuel debris by combining theoretical models and a large amount of photon transport calculations with PHITS code.