Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Takamizawa, Hisashi; Hata, Kuniki; Nishiyama, Yutaka; Toyama, Takeshi*; Nagai, Yasuyoshi*
Journal of Nuclear Materials, 556, p.153203_1 - 153203_10, 2021/12
Times Cited Count：3 Percentile：31.78(Materials Science, Multidisciplinary)Solute clusters (SCs) formed in pressurized water reactor surveillance test specimens neutron-irradiated to a fluence of 1 
10
n/cm
were analyzed via atom probe tomography to understand the effect of silicon on solute clustering and irradiation embrittlement of reactor pressure vessel steels. In high-Cu bearing materials, Cu atoms were aggregated at the center of cluster surrounded by the Ni, Mn, and Si atoms like a core-shell structure. In low-Cu bearing materials, Ni, Mn, and Si atoms formed cluster and these solutes were not comprised core-shell structure in SCs. While the number of Cu atoms in clusters was decreased with decreasing nominal Cu content, the number of Si atoms had clearly increased. The cluster radius (
) and number density (
) decreased and increased, respectively, with increasing nominal Si content. The shift in the reference temperature for nil-ductility transition (
RT
) showed a good correlation with the square root of volume fraction (
) multiplied by r (
). This suggested that the dislocation cutting through the particles mechanism dominates the precipitation hardening responsible for irradiation embrittlement. The negative relation between the nominal Si content and RT indicated that increasing of nominal Si content reduces the degree of embrittlement.
Sanada, Yukihisa; Miyamoto, Kenji*; Momma, Hiroyasu*; Miyazaki, Nobuyuki*; Nakasone, Takamasa*; Tahara, Junichiro*; Baba, Shoichiro*; Furuyama, Hiroki*
Marine Technology Society Journal, 55(5), p.222 - 230, 2021/09
Large quantities of volatile radionuclides were released into the atmosphere following the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in March 2011. To evaluate their effect on aquatic organisms and radiocesium behavior in the environment, the monitoring of radioactive cesium in the waterbed soil is important. We developed a dedicated radiation survey device that can both directly measure and collect some sediment samples. A comprehensive test was conducted using this device, which was installed in an unmanned surface vehicle at Fukushima offshore contaminated by radiocesium that resulted from the FDNPS accident. Consequently, the effectiveness of this device was confirmed because the measurement results of the sediment-core sample and in-situ radiation survey results show a good correlation. A successful application of this device in the time of post-nuclear facility accident is expected.
Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Komanome, Hirohisa*; Miura, Kuniaki*; Ishihara, Masahiro
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04
After the accident at the Fukushima Dai-ichi (1F) Nuclear Power Plant (NPP), the Japanese Government referred to "Enhancement of instrumentation to identify the status of the reactors and PCVs", in the report of Japanese government to the IAEA ministerial conference in June 2011. In response to these provisions, a research and development of a monitoring system for NPPs situations during severe accidents started in November 2012. The objectives of the R&D are composed of radiation-resistant monitoring camera, radiation-resistant in-water transmission system, and heat-resistant signal cable. For all the three objectives, the elemental technologies have been already developed and now trial system are being fabricated and tested under simulated conditions of severe accidents. The results will enable us to determine the basic specifications of the systems and to provide the information about application limits for users.
Kawakubo, Yoko; Sekine, Megumi; Tomikawa, Hirofumi
JAEA-Review 2016-017, 57 Pages, 2016/10
JAEA-Review-2016-017.pdf:7.73MB
Nuclear transparency is recognized as essential to provide additional assurance and enhance confidence building in the Asia-Pacific as this region has a broad spectrum of nuclear development underway and planned in the future. It is expected that elevated nuclear transparency should also supplement and reinforce International Atomic Energy Agency (IAEA) safeguards. With this recognition, Japan Atomic Energy Agency (JAEA) has committed various studies and activities for enhancing regional transparency mainly with U.S. Department of Energy (DOE) and its national laboratories. The efforts include transparency concept study, development of the remote monitoring system at the Experimental Fast Reactor JOYO, cooperation to Council for Security and Cooperation in Asia Pacific (CSCAP) to develop internet-based transparency tools, establishment of Information Sharing Framework (ISF), and the hosting of a series of workshops. Based on all the achievements of the past efforts, JAEA is now moving from "study phase" toward the "implementation phase" of information sharing for enhancing its nuclear transparency. The ISF website was opened in 2015 as a part of Asia Pacific Safeguards Network (APSN) website for JAEA to provide relevant information to APSN members. This report summarizes the past studies and activities performed in JAEA for almost 20 years to enhance regional nuclear transparency and discusses the future prospect.
Nishimura, Akihiko; Terada, Takaya; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya
Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 6 Pages, 2014/07
Since 2007, JAEA has been developing laser based technologies of structural health monitoring. The FBG sensor made by femtosecond laser processing will be the best candidate. To make the best use of the heat resistant characteristic, the FBG sensor was embedded in metal mold by laser cladding. A groove was processed to the surface of a SUS metal plate. We used a QCW laser to weld a filler wire on the plate. A series of weld beads perfectly formed a sealing clad on the groove. Though the FBG sensor was buried tightly, no degradation on the reflection spectrum was detected after the processing. The FBG sensor could detect the vibration of the plate caused by impact shocks and audio vibration. The reflection peak of the FBG sensor under laser cladding condition was shifted to be 6 nm. We demonstrated that the corresponded temperature derive from the reflection peak shift reached 600 degrees in heat shock experiments. The installation procedure of a FBG sensor using a portable laser cladding machine was described.
Shinohara, Nobuo; Inoue, Yoji; Uchikoshi, Takako*; Oda, Tetsuzo*; Kumata, Masahiro; Kurosawa, Yoshiaki; Hirota, Naoki*; Hokida, Takanori; Nakahara, Yoshinori*; Yamamoto, Yoichi
Dai-25-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.51 - 58, 2005/00
The Japan Atomic Energy Research Institute (JAERI) conducts researches and developments related to Comprehensive Nuclear-Test-Ban Treaty (CTBT) on the basis of Japan's pragmatic and progressive efforts toward peaceful use of atomic energy and non-proliferation with the goal of realizing a peaceful and safe world free from nuclear weapons. The Treaty aims for the establishment of a global verification regime comprising an International Monitoring System (IMS) and the JAERI has engaged in the following activities: construction and operation of the radionuclide monitoring stations at Okinawa (RN37) and Takasaki (RN38) and the certified radionuclide laboratory at Tokai (RL11) as specified in Annex 1 of CTBT Protocol, and preparation of the National Data Center at Tokai (JAERI NDC). Research activities of JAERI related to the CTBT verification regime are presented in the paper. The subjects of this presentation are (1) an overview of the CTBT verification regime, (2) construction and operation of RN37, RN38 and RL11, and (3) preparation of the JAERI NDC for radionuclide data.
Takano, Shoji*; Totsuka, Toshiyuki; Yonekawa, Izuru
KEK Proceedings 2003-16 (CD-ROM), 4 Pages, 2004/02
no abstracts in English
Suzudo, Tomoaki; Nabeshima, Kunihiko; Takizawa, Hiroshi*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(4), p.500 - 509, 2003/12
A new methodology to construct distributed computing systems specially targeting nuclear power plant monitoring systems is proposed. In this framework, a monitoring system is composed of multiple modules and a client that administrates them. Each module is designed as a TTY-based program, and therefore has a great flexibility when it is developed. The client holds virtual modules, each of which works as an interface to a module in the remote hosts. Because the virtual modules are defined as a class in the meaning of object-oriented programming, the whole system is easily structured. A prototype of neural-network-based monitoring system has been developed utilizing this methodology, and the expected advantages have been confirmed.
Ooka, Norikazu*; Ishii, Toshimitsu
Hihakai Kensa, 52(5), p.235 - 239, 2003/05
no abstracts in English
Yamamoto, Yoichi; Hokida, Takanori; Hirota, Naoki*; Oda, Tetsuzo; Nakahara, Yoshinori; Kumata, Masahiro; Inoue, Yoji; Uchikoshi, Takako*; Shinohara, Nobuo; Usuda, Shigekazu
Dai-23-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.53 - 60, 2002/12
The Japan Atomic Energy Research Institute (JAERI) has developed the National Data Center (NDC) for radionuclide as part of the international monitoring regime related to the Comprehensive Nuclear-Test-Ban Treaty (CTBT). JAERI NDC already started to input gamma-ray spectrum data obtained from several International Monitoring System (IMS) stations into a database. Data analysis reports made by the International Data Center (IDC) are also stored in the database. Some software tools are under development for the NDC's independent analysis such as investigation of existence of the radionuclides derived from nuclear explosion and presumptive analysis of source location of radionuclide release. The NDC system will also be able to post IMS data and analysis results to the authorized users on the Internet. This paper presents the role, current state of system development and future plan of JAERI NDC.
Kumata, Masahiro; Oda, Tetsuzo; Miyamoto, Yutaka; Uchikoshi, Takako*; Nakahara, Yoshinori; Yamamoto, Yoichi; Hokida, Takanori; Hirota, Naoki*; Inoue, Yoji; Shinohara, Nobuo
Dai-23-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.39 - 44, 2002/12
The International Monitoring System (IMS) will be established across the world to verify compliance with the Comprehensive Test Ban Treaty (CTBT). The IMS will be capable of detecting and identifying nuclear explosions of detonated within the atmosphere, underwater and underground. 321 monitoring stations will be set around the world as a monitoring network of the IMS. The four technologies of seismology, hydroacoustic, infrasound, and radionuclide will be used for monitoring purposes. In order to build the radionuclide monitoring network, 80 radionuclide stations were chosen. Particles in the atmosphere are collected on a filter at each station to measure radioactivity by a HP-Ge detector. Further, 40 out of these 80 stations will be equipped with an automatic radioactive noble gas sampler/analyzer. The JAERI is establishing infrastructure to host radionuclide air monitoring equipment for two raionuclide stations in Japan. This paper presents the current status of the establishment and promising performance of the stations in Japan.
Tachibana, Haruo; Yamaguchi, Takenori; Matsuoka, Shungo*; Nemoto, Shintaro*; Kurosawa, Naohiro*
Proceedings of 1st Asian and Oceanic Congress for Radiation Protection (AOCRP-1) (CD-ROM), 7 Pages, 2002/10
An environmental radiation monitoring system in Tokai establishment of JAERI is composed of 14 monitoring posts, 4 monitoring stations, 2 drainage monitors and the monitoring data observation center. These monitoring posts and stations measure the gamma dose rate, and the monitoring stations measure the radioactive air concentration too. Drainage monitors measure the radioactive concentration in drain water. We developed the environmental radiation dose information system used by cellular phone for observing the monitoring data in day and night, working day and holiday at everyplace in Japan. This information system shows us the every minute or every 10 minutes monitoring data table and data trend graph on the cellular phone display. In the emergency situation, this system helps for speedy response such as the notification to the JAERI staffs, starting the emergency environmental monitoring activities, reporting the dose rate and concentration to the national and local authorities, and establishment of the emergency response team in JAERI.
Onizawa, Kunio; Van Walle, E.*; Pavirich, W.*; Nanstad, R.*
NUREG/CR-6777, 81 Pages, 2002/08
no abstracts in English
Shinohara, Kunihiko; Takeishi, Minoru; ; ; Mizutani, Tomoko
JNC TN8440 2001-019, 141 Pages, 2001/11
JNC-TN8440-2001-019.pdf:12.69MB
This report was written about the effluent control in JNC Tokai Works from 1
April 2000 to 31 March 2001. In this period, the quantities and concentrations of retroactivities in liquid waste from Tokai Works were under the discharge limits of "Safety Regulations for the Tokai Reprocessing Plant", "Safety Regulations for the Tokai Reprocessing Plant" and regulations of government.
Kobayashi, Tadayoshi; Miyajima, Kazutoshi; Yanagihara, Satoshi
Nihon Robotto Gakkai-Shi, 19(6), p.706 - 709, 2001/09
no abstracts in English
*
JNC TN1400 2001-013, 70 Pages, 2001/08
JNC-TN1400-2001-013.pdf:5.13MB
no abstracts in English
Onizawa, Kunio; Suzuki, Masahide
Effects of Radiation on Materials: 20th International Symposium (ASTM STP 1405), p.79 - 96, 2001/07
no abstracts in English
Maruo, Yoshihiro; ; Takeishi, Minoru; ; ; Takeyasu, Masanori;
JNC TN8440 2001-011, 146 Pages, 2001/06
JNC-TN8440-2001-011.pdf:2.98MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed since 1975, based on "Safety Regulations for the Tokai Reprocessing Plant, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitants due to the radioactivity discharged from the plant during April 2000 to March 2001. Appendices present comprehensive information, such as monitoring program, monitoring results, meteorological data and annual discharges from the plant.
Ito, Yasuhisa; Noda, Kimio; ;
JNC TN8410 2001-018, 67 Pages, 2001/04
JNC-TN8410-2001-018.pdf:2.96MB
There are waste storage pits where non-radioactive wastes generated from plutonium fuel facilities were stored in JNC Tokai Works. But radioactive wastes were found in one of the pit during wastes arrangement works. Therefore we set the pit temporary controlled area and recovered wastes from it. This report describes the radiation control technique of recovery work in detail.
Nakazawa, Takashi; Kikuchi, Hisaki; Yasu, Katsuji; Yoshino, Toshiaki; Ashikagaya, Yoshinobu; Sato, Koichi; Minowa, Yuji; Nomura, Toshibumi
JAERI-Tech 2001-010, 125 Pages, 2001/03
no abstracts in English
