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JAEA Reports

Tritium removal of heavy water system and helium system in FUGEN

Takiya, Hiroaki; Kadowaki, Haruhiko; Matsushima, Akira; Matsuo, Hidehiko; Ishiyama, Masahiro; Aratani, Kenta; Tezuka, Masashi

JAEA-Technology 2020-001, 76 Pages, 2020/05


Advanced Thermal Reactor (ATR) FUGEN was operated for about 25 years, and now has been proceeding decommissioning after the approval of the decommissioning plan in Feb. 2008. The reactor, heavy water system and helium system are contaminated by tritium because of neutron absorption of heavy water, which is a moderator. Before dismantling these facilities, it is necessary to remove tritium from them for not only reducing the amount of tritium released to surrounding environment and the risk of internal exposure by tritium but also ensuring the workability. In first phase of decommissioning (Heavy Water and Other system Decontamination Period), tritium decontamination of the reactor, heavy water system and helium system started in 2008 and completed in 2018. This report shows the results of tritium decontamination of the reactor, heavy water system and helium system.

Journal Articles

Toward technological contributions to remote operations in the decommissioning of the Fukushima Daiichi Nuclear Power Station

Kawabata, Kuniaki

Japanese Journal of Applied Physics, 59(5), p.050501_1 - 050501_9, 2020/05

This paper describes the decommissioning work being undertaken at the Fukushima Daiichi Nuclear Power Station of the Tokyo Electric Power Company Holdings Inc.'s (FDNPS) using remote controlled robotic systems, as well as lessons learned from past remote task executions. We also summarize the issues to be considered in promoting safe, steady, and efficient decommissioning based on past experiences. In response to these issues, we are developing test methods for performance evaluation of the robots for nuclear decommissioning, robot simulator for operator proficiency training, and information generation methods to improve the operator's status awareness. The current status of technological development is also described.

Journal Articles

Rapid analytical method of $$^{90}$$Sr in urine sample; Rapid separation of Sr by phosphate co-precipitation and extraction chromatography, followed by determination by triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS)

Tomita, Jumpei; Takeuchi, Erina

Applied Radiation and Isotopes, 150, p.103 - 109, 2019/08

 Times Cited Count:1 Percentile:53.3(Chemistry, Inorganic & Nuclear)

A rapid analytical method for determining $$^{90}$$Sr in urine samples (1-2 L) was developed to assess the internal exposure of workers in a radiological emergency. Strontium in a urine sample was rapidly separated by phosphate co-precipitation, followed by extraction chromatography with a tandem column of Pre-filter, TRU and Sr resin, and the $$^{90}$$Sr activity was determined by ICP-MS/MS. Measurement in the MS/MS mode with an O$$_{2}$$ reaction gas flow rate 1 mL min$$^{-1}$$ showed no tailing of $$^{88}$$Sr at m/z = 90 up to 50 mg-Sr L$$^{-1}$$. The interferences of Ge, Se and Zr at m/z = 90 were successfully removed by chemical separation. This analytical method was validated by the results of the analyses of synthetic urine samples (1.2-1.6 L) containing a known amount of $$^{90}$$Sr along with 1 mg of each of Ge, Se, Sr and Zr. The turnaround time for analysis was about 10 h, and the detection limit of $$^{90}$$Sr was approximately 1 Bq per urine sample.

Journal Articles

Development of a function calculating internal dose coefficients based on ICRP 2007 Recommendations

Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki

BIO Web of Conferences (Internet), 14, p.03011_1 - 03011_2, 2019/05

 Times Cited Count:0 Percentile:100

Dose coefficients, which are committed effective dose per unit intake of radionuclides, are fundamental amounts for dose estimation and protection standards against internal exposures. In this study, we built a calculation function of dose coefficients using the latest dosimetric models and data as a part of development of internal dosimetry code in accordance with 2007 Recommendations of the International Commission of Radiological Protection (ICRP). Quality of the function was assured by comparing the results generated by the function to values recorded in a database of dose coefficients for workers provided by ICRP. In the presentation, we will report the results of quality assurance and the future plans of code development.

JAEA Reports

Preliminary missions for the decommissioning of the laboratory building No.1 for the plutonium research program

Segawa, Yukari; Horita, Takuma; Kitatsuji, Yoshihiro; Kumagai, Yuta; Aoyagi, Noboru; Nakada, Masami; Otobe, Haruyoshi; Tamura, Yukito*; Okamoto, Hisato; Otomo, Takashi; et al.

JAEA-Technology 2016-039, 64 Pages, 2017/03


The laboratory building No.1 for the plutonium research program (Bldg. Pu1) was chosen as one of the facilities to decommission by Japan Atomic Energy Agency Reform in September, 2013. The research groups, users of Bldg. Pu1, were driven by necessity to remove used equipment and transport nuclear fuel to other facilities from Bldg. Pu1. Research Group for Radiochemistry proactively established the Used Equipment Removal Team for the smooth operation of the removal in April, 2015. The team classified six types of work into the nature of the operation, removal of used equipment, disposal of chemicals, stabilization of mercury, stabilization of nuclear fuel, transportation of nuclear fuel and radioisotope, and survey of contamination status inside the glove boxes. These works were completed in December, 2015. This report circumstantially shows six works process, with the exception of the approval of the changes on the usage of nuclear fuel in Bldg. Pu1 to help prospective decommission.

Journal Articles

Replacement of the glove box panel in Nuclear Fuel Reprocessing Facility

Masui, Kenji; Yamamoto, Masahiko; Kuno, Takehiko; Surugaya, Naoki

Nippon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.25 - 30, 2016/07

no abstracts in English

JAEA Reports

Procedures of chemical analysis of radioactive waste for decommissioning of TEPCO'S Fukushima Daiichi Nuclear Power Station

Yonekawa, Minoru; Iwasaki, Maho; Shimada, Kozue; Yanagiya, Shoko; Tsukada, Manabu; Iizuka, Yoshiyuki; Kaneko, Munenori; Unno, Toshimichi

JAEA-Testing 2015-002, 151 Pages, 2016/03


Preparatory Office for Hot Laboratory Operation Management in Fukushima Research Infrastructural Creation Center has advanced research and development for decommissioning of TEPCO'S Fukushima Daiichi Nuclear Power Station. For this purpose, work procedure manual of chemical analysis for safety evaluation on processing, disposal and management of radioactive waste such as low dose level rubbles and fuel debris has been prepared. The manual will be used for personnel training and animation function of PowerPoint was used as the beginner of the chemical analysis to understand easily. This report describes about nuclides which were established analysis method and completed to make animation of work procedure.

JAEA Reports

Work and safety managements for on-site installation, commissioning, tests by EU of quench protection circuits for JT-60SA

Yamauchi, Kunihito; Okano, Jun; Shimada, Katsuhiro; Omori, Yoshikazu; Terakado, Tsunehisa; Matsukawa, Makoto; Koide, Yoshihiko; Kobayashi, Kazuhiro; Ikeda, Yoshitaka; Fukumoto, Masahiro; et al.

JAEA-Technology 2015-053, 36 Pages, 2016/03


The superconducting Satellite Tokamak machine "JT-60SA" under construction in Naka Fusion Institute is an international collaborative project between Japan (JA) and Europe (EU). The contributions for this project are based on the supply of components, and thus European manufacturer shall conduct the installation, commissioning and tests on Naka site. This means that Japan Atomic Energy Agency (JAEA) had a quite difficult issue to manage the works by European workers and their safety although there is no direct contract. This report describes the approaches for the work and safety managements, which were agreed with EU after the tough negotiation, and then the completed on-site works for Quench Protection Circuits (QPC) as the first experience for EU in JT-60SA project. With the help of these approaches by JAEA, the EU works for QPC were successfully completed with no accident, and a great achievement was made for both EU and JA.

Journal Articles

Development of public dose assessment code for decommissioning of nuclear reactors (DecDose)

Shimada, Taro; Oshima, Soichiro; Ishigami, Tsutomu; Yanagihara, Satoshi

Proceedings of 10th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '05) (CD-ROM), 8 Pages, 2005/09

In order to review an operator's "Decommissioning Plan" applied to the regulatory body for approval accurately and quickly, Public Dose Assessment Code for Decommissioning of Nuclear Reactors (DecDose) was developed. It evaluates public exposure doses for each year during dismantling activities in accordance with the "Decommissioning Plan". DecDose takes account of various exposure pathways such as cloudshine, surface ground deposition, ingestion of seafood, and direct and skyshine radiation based on the quantity of radionuclides discharged to the environment, and containers stored in the facility in consideration of cutting and storage of components and structures. Example evaluations with DecDose have shown that it is a useful tool for assessing public dose during decommissioning of nuclear reactors.

Journal Articles

Relation between neutron dosemeter readings and calibration fields for various workplace spectra

Saegusa, Jun; Tanimura, Yoshihiko; Yoshizawa, Michio

Proceedings of 11th International Congress of the International Radiation Protection Association (IRPA-11) (CD-ROM), 8 Pages, 2004/05

Relationships between dosemeter readings and the true dose equivalents at various workplaces were analyzed. From the analysis, it was shown that depending on the types of dosemeters, there exist a suitable calibration field, and the field differs by the difference of response characteristics of dosemeters. For the precise estimation of dose equivalent, it is important that measurement is carried out under the careful considerations of the difference between neutron spectrum at workplace and at calibration field, as well as the improvement of response characteristics of the dosemeters.

Journal Articles

Recent activities related to decommissioning in nuclear energy agency of OECD

Yanagihara, Satoshi

Dekomisshoningu Giho, (28), p.2 - 9, 2003/10

Decommissioning of nuclear facilities has been actively progressed in the major member countries participating to OECD/NEA. The NEA has recognized necessity of studying various issues related to decommissioning nuclear facilities and it has made an approach to solve the issues from various ways. In the cooperative program for decommissioning (CPD), information on decommissioning projects has been exchanged among the member countries. In the working party on decommissioning and dismantling (WPDD), recent issues have been studied in terms of regulation, implementation of decommissioning projects and research and development on technologies. Decommissioning cost and regulatory practices were also studies and the reports were published, which will be useful for understanding the present issues on decommissioning in the world. The NEA's activity on decommissioning will be valuable for us to implement decommissioning projects in safe and economical manner in Japan. This report deals with the recent NEA activities on decommissioning.

Journal Articles

Shutdown dose evaluation experiment for ITER

Morimoto, Yuichi*; Ochiai, Kentaro; Sato, Satoshi; Hori, Junichi; Yamauchi, Michinori*; Nishitani, Takeo

Fusion Engineering and Design, 69(1-4), p.643 - 648, 2003/09

 Times Cited Count:3 Percentile:72.62(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Development of computer systems for planning and management of reactor decommissioing

Yanagihara, Satoshi

Nippon Genshiryoku Gakkai-Shi, 44(10), p.734 - 737, 2002/10

no abstracts in English

Journal Articles

Development of computer programs for occupational doses estimation in dismantling of nuclear facilities

Shimada, Taro; Sukegawa, Takenori; Yanagihara, Satoshi; Sato, Tadamichi*; Sakai, Shinichi*

Proceedings of 9th Biennial International Conference on Nuclear and Hazardous Waste Management (Spectrum '02) (CD-ROM), 6 Pages, 2002/08

no abstracts in English

Journal Articles

Development of re-irradiation techniques using JMTR

Matsui, Yoshinori; Ide, Hiroshi; Itabashi, Yukio; Kikuchi, Taiji; Ishikawa, Kazuyoshi; Abe, Shinichi; Inoue, Shuichi; Shimizu, Michio; Iwamatsu, Shigemi; Watanabe, Naoki*; et al.

UTNL-R-0416, p.5_1 - 5_10, 2002/03

no abstracts in English

JAEA Reports

JCO criticality accident termination operation

Kanamori, Masashi

JNC-TN8440 2001-018, 50 Pages, 2001/12


On September 30 at around 10:35 AM, criticality accident occurred at the JCO's conversion building in Tokai-mura. Since criticality accident had not been anticipated, neither devices for termination of criticality accident nor neutron detectors were available. Immediately after the information of the accident, our emergency staff(Japan Nuclear cycle development institute staff) went to JCO site, to measure the intensity of neutrons and gammas. There were four main tasks, first one was to measure the radiation intensity, second one was to terminate the criticality accident, third one is to alert the residents surrounding the JCO site, fourth one is to evacuate the employees in the site. These tasks were successfully performed until October 1. This paper describes about how these operations were performed by the relevant staffs.

JAEA Reports

Radiation control on wastes recovery work in wastes storage pit

Ito, Yasuhisa; Noda, Kimio; ;

JNC-TN8410 2001-018, 67 Pages, 2001/04


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.

JAEA Reports

Mock-up test of remote controlled dismantling apparatus for large-sized vessels (Contract research)

Myodo, Masato; Okane, Shogo; Miyajima, Kazutoshi

JAERI-Tech 2001-025, 59 Pages, 2001/03


no abstracts in English

JAEA Reports

Improvement of the technique for stack monitoring based on behavior analysis of natural radio-nuclides; The technique for reducing the value of the exhaust monitor's background

Izaki, Kenji; Noda, Kimio; ; Kashimuta, Yoshio*

JNC-TN8410 2001-005, 30 Pages, 2001/01


Stack monitoring is the most important work in radiation control works. Exhaust monitors used for stack monitoring have the background (which is the counts by natural radio-nuclides) on normal condition, and the values of the background vary with the facilities. Therefore, if the value of background is high, it is difficult to estimate rapidly the radioactive concentration in the exhaust. In order to estimate rapidly the radioactive concentration in exhaust, we analyzed the behavior of natural radioactivity in the facilities and examine the technique fo reducing the value of the background. As a result of the examination, we found that it is possible to estimate rapidly if we change over the monitoring point to immediately after the HEPA filters on the exhaust duct. In this reports, the analyzed results of behavior of natural radio-nuclides in the facilities and the technique for reducing the values of the background are described. To reduce the value of the background has a major effect on not only rapidly estimating the radioactive density in the exhaust but also finding the unusual things on stack monitoring.

JAEA Reports

Monte Carlo simulation on nuclear energy study, 2; Annual report of nuclear code evalution committee

Nuclear Code Evaluation Special Committee of Nuclear Code Research Committee

JAERI-Review 2000-027, 197 Pages, 2001/01


no abstracts in English

103 (Records 1-20 displayed on this page)