Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 71

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Main outputs from the OECD/NEA ARC-F Project

Maruyama, Yu; Sugiyama, Tomoyuki*; Shimada, Asako; Lind, T.*; Bentaib, A.*; Sogalla, M.*; Pellegrini, M.*; Albright, L.*; Clayton, D.*

Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.4782 - 4795, 2023/08

Journal Articles

Recent progress of $$^{135}$$Cs concentration and $$^{135}$$Cs/$$^{137}$$Cs isotopic ratio measurement

Shimada, Asako

Bunseki Kagaku, 71(12), p.625 - 633, 2022/12

Cesium-135 is one of the important nuclides to assess the safe disposal of High Level Waste (HLW). Therefore, the calculation code and library to evaluate the $$^{135}$$Cs concentration in HLW have been improved through comparisons with experimental results. On the other hand, even basic data of $$^{135}$$Cs, such as its half-life, have large uncertainty. Because the $$^{135}$$Cs/$$^{137}$$Cs isotopic ratio suggests its origin and introduction date, the ratios in environmental samples are measured to study global fallout from nuclear weapons testing and nuclear accidents. Such measurement methods was attracted attention, in particular, after the accident at the Fukushima Daiichi Nuclear Power Station. Measurement of the $$^{135}$$Cs/$$^{137}$$Cs isotopic ratio in environmental samples was challenging because the radiocesium has a very low concentration and it co-exists with huge amounts of Ba isotopes, which are isobaric interfering nuclides, are co-exist. Chemical separation methods were developed to eliminate interfering nuclides and improve the performance of the mass spectrometer to enable the measurement of the ratios. In this review, the features of the $$^{135}$$Cs/$$^{137}$$Cs isotopic ratio for each origin and recent developments in measurement techniques are summarized.

Journal Articles

Radiochemical analysis of the drain water sampled at the exhaust stack shared by Units 1 and 2 of the Fukushima Daiichi Nuclear Power Station

Shimada, Asako; Taniguchi, Yoshinori; Kakiuchi, Kazuo; Ohira, Saki; Iida, Yoshihisa; Sugiyama, Tomoyuki; Amaya, Masaki; Maruyama, Yu

Scientific Reports (Internet), 12(1), p.2086_1 - 2086_11, 2022/02

 Times Cited Count:0 Percentile:35.78(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Determination of $$^{135}$$Cs/$$^{137}$$Cs isotopic ratio in soil collected near Fukushima Daiichi Nuclear Power Station through mass spectrometry

Shimada, Asako; Tsukahara, Takehiko*; Nomura, Masao*; Kim, M. S.*; Shimada, Taro; Takeda, Seiji; Yamaguchi, Tetsuji

Journal of Nuclear Science and Technology, 58(11), p.1184 - 1194, 2021/11

 Times Cited Count:5 Percentile:68.53(Nuclear Science & Technology)

Determining the completeness of nuclear reactor decommissioning is an important step in safely utilizing nuclear power. For example, $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Station (FDNPS) accident can be treated as background radioactivity, so determining the origin of $$^{137}$$Cs is essential. To accomplish this, measuring the $$^{135}$$Cs/$$^{137}$$Cs isotope ratio can be useful, so this study optimized a solvent extraction method, with calix[4]arene-bis(t-octylbenzo-crown-6) [BOBCalixC6] in 1-octanol, to purify radioactive Cs, radiocesium, from a solution of major environmental soil elements and mass spectrometry interference elements. This optimized method was applied to Cs purification in soil samples (40 g), and the final solutions contained a total of 10$$mu$$g/ml of the major soil elements and ng/ml concentrations at most of interfering elements. Soil samples collected near the FDNPS were then purified, and the $$^{135}$$Cs/$$^{137}$$Cs isotope ratios were measured, using both thermal ionization mass spectrometry (TIMS) and triple quadrupole induced coupled plasma mass spectrometry (ICP-QQQ). The results of each of these measurements were compared, and we found that Cs isotope ratios obtained by TIMS were more precise, by an order of magnitude, while the ICP-QQQ results possessed good abundance sensitivities. A slightly higher $$^{135}$$Cs/$$^{137}$$Cs ratio in the northwest area of the FDNPS was observed, while other areas exhibited similar values, all within the measurement error range, which indicated different origins of radiocesium. These results agreed with previously reported $$^{134}$$Cs/$$^{137}$$Cs activity distributions, suggesting that this ratio may be useful in identifying radiocesium origins for evaluating future nuclear reactor decommissions.

Journal Articles

Dose estimation of landfill disposal of removed soil generated outside Fukushima Prefecture

Shimada, Asako; Sawaguchi, Takuma; Takeda, Seiji

Health Physics, 120(5), p.517 - 524, 2021/05

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

Journal Articles

Appreciate new century award

Shimada, Asako

Nihon Bunseki Kagakukai Kanto Shibu Nyusu, (31), p.7 - 8, 2021/00

I am very glad to win a prize, new century award of Kanto branch of The Japan Society for Analytical Chemistry. I deeply appreciate recommender and co-workers. The title of award was "Development of analytical method of difficult to measure nuclides in radioactive wastes", and especially development of analytical method for Am-242m, Mo-93, and I-129 was recognized. By measuring beta-ray of Am-242, which is progeny nuclide of Am-242m and having high intensity and shorter half-life, measuring time was shortened to approximately 1/20 compare to traditional method. Analyzed Mo-93 example was extremely few. When Mo-93 was analyzed via X-ray, Zr-93 and Nb-93m were the interfering nuclides, therefore, separation method of Mo from Zr and Nb was developed and the method was applied to the rubble sample collected at the Fukushima Daiichi Nuclear Power Station (FDNPS). Official method to measure I-129 in environmental samples were optimized to measure I-129 in the contaminated water collected at FDNPS.

Journal Articles

Consideration on modeling of Nb sorption onto clay minerals

Yamaguchi, Tetsuji; Ohira, Saki; Hemmi, Ko; Barr, L.; Shimada, Asako; Maeda, Toshikatsu; Iida, Yoshihisa

Radiochimica Acta, 108(11), p.873 - 877, 2020/11

 Times Cited Count:7 Percentile:68.59(Chemistry, Inorganic & Nuclear)

Journal Articles

Sensitivity analysis of external exposure dose for future burial measures of decontamination soil generated outside Fukushima prefecture

Shimada, Asako; Sawaguchi, Takuma; Takeda, Seiji

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 5 Pages, 2020/08

no abstracts in English

Journal Articles

Dose estimation in the recycling of removed soil for land reclamation

Shimada, Asako; Nemoto, Hiromi*; Sawaguchi, Takuma; Takeda, Seiji

Mechanical Engineering Journal (Internet), 7(3), p.19-00569_1 - 19-00569_17, 2020/06

After treatments such as sieve classification and washing of decontamination soil taken in Fukushima prefecture, recycling of the treated soil in which radioactivity concentration level is relatively low to public engineering works is invented to reduce the amount of the decontamination soil that must be disposed of. In the present study, dose estimation for workers and the public was conducted from the viewpoint of application of recycling material of decontamination soil for land reclamation by considering exposure pathways from the construction to the servicing of the land as a greenery-covered area. In the case of revegetation with trees, uptake of Cs into trees was considered and the exposure from trees, trimmed or thinned trees, and organic deposit made from litter fall were evaluated. From the results, the concentration levels of radiocesium, $$^{134}$$Cs and $$^{137}$$Cs, for which the annual effective exposure dose does not exceed 1 mSv/y was calculated. In addition, the thickness of the cover soil required to maintain the exposure dose lower than 10 $$mu$$Sv/y for the public during servicing was ascertained. Furthermore, disasters were considered; for instance, by considering that tsunamis, fires, and concentrated heavy rain can increase exposure doses based on changes in the conditions of the reclamation land, we confirmed that the additional exposure dose during disaster and rehabilitation is lower than 1 mSv/y. Based on these evaluation results, we determined the concentration levels amenable to recycling.

Journal Articles

Dose estimation for contaminated soil storage in living environment

Takai, Shizuka; Shimada, Asako; Sawaguchi, Takuma; Takeda, Seiji; Kimura, Hideo

Radiation Protection Dosimetry, 188(1), p.1 - 7, 2020/01

 Times Cited Count:0 Percentile:0.01(Environmental Sciences)

After the Fukushima Nuclear Power Plant accident, most of radiocesium-contaminated soil generated from decontamination activities outside Fukushima prefecture has been stored at decontamination sites such as schools, parks and residential lands (storage at sites) according to the Decontamination Guidelines. However, additional exposure due to the present storage has not been evaluated. Moreover, entering storage sites, which is not restricted for storage at sites, was not considered in safety assessment conducted in the guidelines. To continue the storage and confirm the effectiveness, understanding of present possible exposures is important. In this study, we evaluated exposure doses for residents and users of storage sites based on the present situation. As a result, annual doses due to residence were 10$$^{-2}$$ to 10$$^{-3}$$ mSv y$$^{-1}$$ and doses due to annual entries were of the order of 10$$^{-3}$$ mSv y$$^{-1}$$. Hence, we confirmed that the exposure due to present storage outside Fukushima is significantly less than 1 mSv y$$^{-1}$$.

Journal Articles

Dose estimation in recycling of decontamination soil from the Fukushima Daiichi NPS accident for land reclamation

Shimada, Asako; Nemoto, Hiromi*; Sawaguchi, Takuma; Takeda, Seiji

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05

no abstracts in English

Journal Articles

Report of participation in Radiochemical Conference

Shimada, Asako

Hosha Kagaku, (38), p.30 - 31, 2018/09

no abstracts in English

Journal Articles

Study on Mo structure in simulated dissolved solutions of activated metal waste

Shimada, Asako; Okamoto, Yoshihiro

Photon Factory Activity Report 2017, 2 Pages, 2018/00

no abstracts in English

JAEA Reports

Development of $$^{93}$$Zr, $$^{93}$$Mo, $$^{107}$$Pd and $$^{126}$$Sn analytical methods for radioactive waste from Fukushima Daiichi Nuclear Power Station

Aono, Ryuji; Sato, Yoshiyuki; Shimada, Asako; Tanaka, Kiwamu; Ueno, Takashi; Ishimori, Kenichiro; Kameo, Yutaka

JAEA-Technology 2017-025, 32 Pages, 2017/11

JAEA-Technology-2017-025.pdf:1.45MB

We have developed analytical methods for $$^{93}$$Zr, $$^{93}$$Mo, $$^{107}$$Pd and $$^{126}$$Sn, which are considered important in terms of the safety assessment of radioactive waste disposal. The methods are specialized for the wastes left after Fukushima accident. As the main analytical sample, we assumed accumulated water / treated water collected at Fukushima Daiichi Nuclear Power Station. As for $$^{93}$$Zr, $$^{93}$$Mo, $$^{107}$$Pd and $$^{126}$$Sn contained in this accumulated water / treated water, we have worked on the development of separation and purification method of target nuclide and improvement of recovery, and summarized these results in this report.

Journal Articles

Development of determination method of $$^{93}$$Mo content in metal waste generated at the Japan Power Demonstration Reactor

Shimada, Asako; Omori, Hiroyuki*; Kameo, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 314(2), p.1361 - 1365, 2017/11

AA2017-0285.pdf:0.49MB

 Times Cited Count:2 Percentile:20.14(Chemistry, Analytical)

A separation method of Mo from Nb, Zr, and the matrix elements of rubble waste was modified to determine the content of $$^{93}$$Mo in metal waste. A separation scheme to treat 1 g of metal waste was established by optimizing the amount of ascorbic acid, the rinsing solution, and repeating of the procedure. A thin-layer source was prepared using direct drop deposition and evaporation to measure $$^{93}$$Mo content. Finally, $$^{93}$$Mo content in the metal waste generated at the Japan Power Demonstration Reactor was analyzed using the developed method.

Journal Articles

Separation of Zr in the rubble waste generated at the Fukushima Daiichi Nuclear Power Station

Shimada, Asako; Kameo, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 311(3), p.1613 - 1618, 2017/03

AA2016-0191.pdf:0.23MB

 Times Cited Count:0 Percentile:10.85(Chemistry, Analytical)

Separation method of Zr using trans uranium resin (TRU resin) was developed. Approximately 100% of Zr, Nb, Bi, Th, and U and a part of Mo and Hg were extracted on the TRU resin from 3 M HNO $$_{3}$$ solution and separated from Li, Be, Mg, Al, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr,Ag, Cd, In, Cs, Ba. Approximately 100% of Zr, Nb, and U were striped from the TRU resin with 0.01 M HF and 10% of Mo, 7.1% of Hg, 77% of Bi, and 20% of Th were also included in the stripping solution. In order to measure $$^{93}$$Zr with inductively coupled plasma mass spectrometry (ICP-MS), Zr has to be separated from Nb and Mo to avoid isobaric interference. Therefore, further purification of Zr using tetra valent actinide resin (TEVA resin) was applied. The developed method was evaluated with the simulated rubble sample solution. Although a part of Zr was eluted during sample loading, most of Zr was extracted on the TRU resin and separated major elements of the rubble sample. Finally, Zr was separated from Nb and Mo with the TEVA resin.

Journal Articles

Development of an extraction chromatography method for the analysis of $$^{93}$$Zr, $$^{94}$$Nb, and $$^{93}$$Mo in radioactive contaminated water generated at the Fukushima Daiichi Nuclear Power Station

Shimada, Asako; Kameo, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 310(3), p.1317 - 1323, 2016/12

 Times Cited Count:7 Percentile:55.72(Chemistry, Analytical)

JAEA Reports

Summary of instructor training program in FY2014 aiming at Asian countries introducing nuclear technologies for peaceful use (Contract program)

Hidaka, Akihide; Nakano, Yoshihiro; Watanabe, Yoko; Arai, Nobuyoshi; Sawada, Makoto; Kanaizuka, Seiichi*; Katogi, Aki; Shimada, Mayuka*; Ishikawa, Tomomi*; Ebine, Masako*; et al.

JAEA-Review 2016-011, 208 Pages, 2016/07

JAEA-Review-2016-011-01.pdf:33.85MB
JAEA-Review-2016-011-02.pdf:27.68MB

JAEA has been conducting the Instructor Training Program (ITP) since 1996 under the auspices of MEXT to contribute to human resource development in currently 11 Asian countries in the field of radiation utilization for seeking peaceful use of nuclear energy. ITP consists of Instructor Training Course (ITC), Follow-up Training Course (FTC) and Nuclear Technology Seminars. In the ITP, trainings or seminars relating to technology for nuclear utilization are held in Japan by inviting nuclear related people from Asian countries to Japan and after that, the past trainees are supported during FTC by dispatching Japanese specialists to Asian countries. News Letter is also prepared to provide the broad range of information obtained through the trainings for local people near NPPs in Japan. The present report describes the activities of FY2014 ITP and future challenges for improving ITP more effectively.

JAEA Reports

Analysis of the radioactivity concentrations in low-level radioactive waste generated from JPDR facilities, 4

Omori, Hiroyuki; Nebashi, Koji; Shimada, Asako; Tanaka, Kiwamu; Yasuda, Mari; Hoshi, Akiko; Tsuji, Tomoyuki; Ishimori, Kenichiro; Kameo, Yutaka

JAEA-Data/Code 2014-029, 31 Pages, 2015/03

JAEA-Data-Code-2014-029.pdf:1.51MB

Simple and rapid methods to evaluate the radioactivity concentrations are required for the radioactive waste generated from research facilities in the Japan Atomic Energy Agency to dispose of in a near-surface repository. In order to establish the methods to evaluate the radioactivity concentrations of miscellaneous solid waste generated from research and testing reactors, we collected and analyzed samples from miscellaneous solid waste generated by the decommissioning of JPDR (Japan Power Demonstration Reactor). In this report, we reported the analytical data determined in fiscal 2014 ($$^{137}$$Cs and $$^{93}$$Mo) and summarized them with the radioactivity concentrations obtained in the past as basic data to consider the evaluation method of radioactivity concentrations in the stored waste taken from JPDR.

Journal Articles

Determination of $$^{129}$$I in the Accumulated radioactive water and processing water of the Fukushima Daiichi Nuclear Power Plant

Shimada, Asako; Sakatani, Keiichi; Kameo, Yutaka; Takahashi, Kuniaki

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1137 - 1140, 2015/02

 Times Cited Count:6 Percentile:46.42(Chemistry, Analytical)

Accumulated radioactive water and processing water were sampled from back and forth of the Accumulated radioactive water processing facility (ARWPF) at Fukushima Daiichi Nuclear Power Plant (FDNPP) to estimate the radioactivity of the secondary waste such as zeolite and sludge adsorbed radioactive material. Separation method of I$$^{-}$$ from the radioactive materials using solid phase extractant, Anion-SR, was developed, and the concentration of $$^{129}$$I in the accumulated water and processing water was determined by Inductively Coupled Plasma Mass Spectrometry including dynamic reaction cell (DRC-ICP-MS).

71 (Records 1-20 displayed on this page)