Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 114

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

Initial decrease in the ambient dose equivalent rate after the Fukushima accident and its difference from Chernobyl

Yoshimura, Kazuya; Saegusa, Jun; Sanada, Yukihisa

Scientific Reports (Internet), 10(1), p.3859_1 - 3859_9, 2020/03

 Times Cited Count:7 Percentile:75.85(Multidisciplinary Sciences)

JAEA Reports

Proceedings of the Fukushima Research Conference on Development of Analytical Techniques in Waste Management (FRCWM 2018); June 19th and 20th, Tomioka Town Art & Media Center, Tomioka, Futaba, Fukushima, Japan

Saegusa, Jun; Koma, Yoshikazu; Ashida, Takashi

JAEA-Review 2018-017, 259 Pages, 2018/12

JAEA-Review-2018-017.pdf:53.88MB

Collaborative Laboratories for Advanced Decommissioning Science (CLADS) is responsible to promote international cooperation in the R&D activities on the decommissioning of Fukushima Daiichi Nuclear Power Station and to develop the necessary human resources. CLADS held the Fukushima Research Conference on Development of Analytical Techniques in Waste Management (FRCWM 2018) on 19th and 20th June, 2018. This report compiles the abstracts and the presentation materials in the above conference.

Journal Articles

Establishment of a Laboratory for $$gamma$$-ray Spectrometry of Environmental Samples Collected in Fukushima

Saegusa, Jun; Yoda, Tomoyuki; Maeda, Satoshi; Okazaki, Tsutomu; Otani, Shuichi; Yamaguchi, Toshio; Kurita, Yoshiyuki; Hasumi, Atsushi; Yonezawa, Chushiro*; Takeishi, Minoru

Proceedings of 14th International Congress of the International Radiation Protection Association (IRPA-14), Vol.3 (Internet), p.1078 - 1085, 2017/11

After the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in March 2011, the Japan Atomic Energy Agency has newly set up a laboratory for radioactivity analysis in Fukushima. At the laboratory, radioactivity concentrations of environmental samples such as soil, water, dust filter, plant, etc., approximately 1,000 samples in a month, are measured with high-resolution $$gamma$$-ray spectrometry systems. The systems employ n-type HPGe detectors from Ortec. Since September 2012, characterization and upgrade of the systems have been performed aimed at enhancing reliability of analysis and convenience of customers. Resolving both systematic and technical issues, the laboratory has been accredited the ISO/IEC 17025 standard as a testing laboratory for radioactivity analysis.

Journal Articles

Using two detectors concurrently to monitor ambient dose equivalent rates in vehicle surveys of radiocesium contaminated land

Takeishi, Minoru; Shibamichi, Masaru; Malins, A.; Kurikami, Hiroshi; Murakami, Mitsuhiro*; Saegusa, Jun; Yoneya, Masayuki

Journal of Environmental Radioactivity, 177, p.1 - 12, 2017/10

AA2016-0534.pdf:1.79MB

By convention radiation measurements from vehicle-borne surveys are converted to the dose rate at 1 m above the ground in the absence of the vehicle. To improve the accuracy of the converted results from vehicle-borne surveys, we investigated combining measurements from two detectors mounted on the vehicle at different heights above the ground. A dual-detector setup was added to a JAEA monitoring car and compared against hand-held survey meter measurements in Fukushima Prefecture. The dose rates obtained by combining measurements from two detectors were within $$pm$$20% of the hand-held reference measurements. The combined results from the two detectors were more accurate than those from either the roof-mounted detector, or the detector inside the vehicle, taken alone. When radiocesium is deficient on a road compared to the adjacent land, mounting detectors high on vehicles yields dose rates closer to the values adjacent to the road. We also investigated mounting heights for vehicle-borne detectors using Monte Carlo $$gamma$$-ray simulations.

Journal Articles

Temperature performance of portable radiation survey instruments used for environmental monitoring and clean-up activities in Fukushima

Saegusa, Jun; Yanagisawa, Kayo; Hasumi, Atsushi; Shimizu, Takenori; Uchida, Yoshiaki*

Radiation Physics and Chemistry, 137, p.210 - 215, 2017/08

 Times Cited Count:1 Percentile:15.39(Chemistry, Physical)

Following the Fukushima Daiichi Nuclear Power Plant (NPP) accident, large-scale radiation monitoring and environmental clean-up activities have been conducted throughout the Fukushima region. Outside air temperatures there reach 40$$^{circ}$$C in summer and -20$$^{circ}$$C in winter, which are beyond the quoted range of many radiation survey instruments. For the purpose, temperature performances of four types of portable Japanese survey instruments which are widely used in Fukushima were experimentally investigated with a temperature-controlled chamber.

Journal Articles

Analysis of ambient-dose-rate trends in Fukushima; Ecological half-life, effect of snow covering

Saegusa, Jun; Yoda, Tomoyuki; Murakami, Mitsuhiro; Takeishi, Minoru

Kankyo Hoshano Josen Gakkai-Shi, 5(2), p.79 - 93, 2017/06

After the Fukushima Daiichi Nuclear Power Plant (NPP) accident in March 2011, environmental radiation monitoring works have been continuously conducted throughout the Fukushima prefecture of Japan. Five-year transitions of ambient dose rates at 15 locations 20-60 km away from the NPPs were precisely analyzed to investigate their chronological change. Measured dose rates were successfully fitted into a function consisting of a factor reflecting the physical decay of radiocesium and the other component such as the weathering effect. The ecological half-lives derived from the function ranged from 3 to 27 years (average 10 years). The radiation shielding effect by snow covering was also studied with the obtained functions. Due to the effect, dose rates were lowered by 15-50% by 20-cm-deep snow covering, and the ambient doses integrated over the five years were found to decrease by up to 7% compared to those without the snow covering that can be predicted from the fit function.

Journal Articles

Survey and countermeasures on radiocesium inflow into a laboratory building for radioactivity analysis

Kurita, Yoshiyuki; Saegusa, Jun; Maeda, Satoshi

Nihon Hoshasen Anzen Kanri Gakkai-Shi, 15(2), p.180 - 185, 2016/11

In 2012, JAEA has established a laboratory in Fukushima-city to implement radioactivity analysis of environmental samples. Key nuclides measured in this laboratory are $$^{134}$$Cs and $$^{137}$$Cs (radiocesium). For the purpose, situation of radiocesium inflow into the laboratory building and its effects were investigated based on high-resolution gamma-spectrometry with germanium detectors. As a result, the surface density of radiocesium in the laboratory was found to be far below the minimum detectable activities of survey instruments routinely used for radiation control purposes.

Journal Articles

Study on pretreatment methods using a rapid combustion apparatus for the analyses of Organically Bound Tritium (OBT) in environmental samples

Manabe, Sachi; Matsubara, Natsumi; Saegusa, Jun; Takeishi, Minoru

KEK Proceedings 2016-8, p.281 - 285, 2016/10

no abstracts in English

Journal Articles

Radioactivity decontamination in and around school facilities in Fukushima

Saegusa, Jun; Tagawa, Akihiro; Kurikami, Hiroshi; Iijima, Kazuki; Yoshikawa, Hideki; Tokizawa, Takayuki; Nakayama, Shinichi; Ishida, Junichiro

Mechanical Engineering Journal (Internet), 3(3), p.15-00609_1 - 15-00609_7, 2016/06

After the Fukushima nuclear accident, JAEA lead off demonstration tests to find out effective decontamination methods for various school facilities in Fukushima. It included (1) dose reduction measures at schoolyards, (2) purification of swimming pool water and (3) removal of surface contamination of playground equipments. Through these tests, they established practical methods suitable for each situation; (1) At school yards, dose rates were drastically reduced by removing topsoil which was then placed in trenches of 1 m deep; (2) For the purification of pool water, the flocculation-coagulation treatment was found to be effective for collecting radiocesium dissolved in the water; (3) Demonstration tests for playground equipments, such as horizontal bars and a sandbox wood frame, suggested that effectiveness of decontamination considerably varied depending on the material, paint or coating condition. This paper reviews these demonstrations.

Journal Articles

Impression on the 23rd International Conference on Nuclear Engineering (ICONE23)

Saegusa, Jun; Kurikami, Hiroshi

Nihon Hoken Butsuri Gakkai Newsletter (Internet), (74), p.15 - 17, 2015/06

Brief summary on the 23rd International Conference on Nuclear Engineering, held on 17-21 May 2015 at the International Conference Hall of Makuhari-Messe was described with the authors' impressions.

Journal Articles

Radioactivity decontamination in and around school facilities in Fukushima

Saegusa, Jun; Tagawa, Akihiro; Kurikami, Hiroshi; Iijima, Kazuki; Yoshikawa, Hideki; Tokizawa, Takayuki; Nakayama, Shinichi; Ishida, Junichiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

After the Fukushima nuclear accident, JAEA lead off demonstration tests to find out effective decontamination methods for various school facilities in Fukushima. It included (1) dose reduction measures at schoolyards, (2) purification of swimming pool water and (3) removal of surface contamination of playground equipments. Through these tests, they established practical methods suitable for each situation; (1) At school yards, dose rates were drastically reduced by removing topsoil which was then placed in trenches of 1 m deep; (2) For the purification of pool water, the flocculation-coagulation treatment was found to be effective for collecting radiocesium dissolved in the water; (3) Demonstration tests for playground equipments, such as horizontal bars and a sandbox wood frame, suggested that effectiveness of decontamination considerably varied depending on the material, paint or coating condition. This paper reviews these demonstrations.

Journal Articles

Detailed deposition density maps constructed by large-scale soil sampling for $$gamma$$-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident

Saito, Kimiaki; Tanihata, Isao*; Fujiwara, Mamoru; Saito, Takashi*; Shimoura, Susumu*; Otsuka, Takaharu*; Onda, Yuichi*; Hoshi, Masaharu*; Ikeuchi, Yoshihiro*; Takahashi, Fumiaki; et al.

Journal of Environmental Radioactivity, 139, p.308 - 319, 2015/01

 Times Cited Count:191 Percentile:99.23(Environmental Sciences)

Journal Articles

Observation of fallout deposition in an outdoor swimming pool 50 km away from the Fukushima Daiichi Nuclear Power Plant

Saegusa, Jun; Yasuda, Ryo; Kurikami, Hiroshi

Radiation Measurements, 60, p.53 - 58, 2014/01

 Times Cited Count:5 Percentile:43.74(Nuclear Science & Technology)

After the Fukushima Daiichi Nuclear Power Plant (NPP) accident, the fallout deposited in an outdoor swimming pool was observed. At a pool situated 50 km away from the NPP, the average concentrations of radiocesium for the water and sediment were quantified as 170 Bq L$$^{-1}$$ and 3.6$$times$$10$$^{5}$$ Bq kg$$^{-1}$$, respectively. Taking account of these concentrations and of the water balance in and around the pool, the deposition density of radiocesium, as of August 2011, was precisely estimated to be 0.32$$pm$$0.03 MBq m$$^{-2}$$ ($$k$$ = 1). The density corroborated the previous results obtained by the other methods, i.e., airborne surveys, in-situ Ge surveys and soil samplings at neighboring locations. The radioactivity concentrations of $$^{89}$$Sr, $$^{90}$$Sr, $$^{238}$$Pu and $$^{239+240}$$Pu in the water were all less than the minimum detectable activities - 2, 0.1, 0.002 and 0.002 Bq L$$^{-1}$$, respectively.

Journal Articles

Observation of $$gamma$$-rays from fallout collected at Ibaraki, Japan, during the Fukushima nuclear accident

Saegusa, Jun; Kikuta, Yasuaki; Akino, Hitoshi

Applied Radiation and Isotopes, 77, p.56 - 60, 2013/07

 Times Cited Count:8 Percentile:59.34(Chemistry, Inorganic & Nuclear)

Measurements of $$gamma$$-ray pulse height distributions were performed for a fallout sample collected at Ibaraki, Japan during the Fukushima accident in March, 2011. The fallout was collected in a pan of water, then evaporated to dryness on a stainless-steel holder. The sample was measured by a germanium detector three times over a year. In the pulse height distribution of the initial measurement, approximately 140 peaks were observed between 50 and 2048 keV energy region. Most of them were either total absorption peak or the sum peak of Te, I or Cs isotopes. Compared to the fallout sampled at the past nuclear accidents, while some nuclides such as Ce and Ru were not detected, $$^{110m}$$Ag etc was prominently observed. Radioactivity concentration of $$^{137}$$Cs was estimated to be at least 1.4$$times$$10$$^{4}$$ Bq m$$^{-2}$$, approximately 14% of which was attributed to rainout.

Journal Articles

Decontamination of outdoor school swimming pools in Fukushima

Saegusa, Jun

Hoshasen, 38(4), p.149 - 154, 2013/07

After the Fukushima Daiichi NPP accident following the Great East Japan Earthquake, not a few school swimming pools in Fukushima prefecture have suspended water discharge, due to concerns that pool water which contains radioactive fallout is discharged into a river or waterway for agricultural use. The Japan Atomic Energy Agency conducted researches and examinations on the existing absorbent method and the flocculation method as ways for decontaminating pool water. By reviewing and improving these methods through decontamination demonstrations at eight pools in Fukushima prefecture, a practical decontamination method for school pools has been established. This report summarizes the methods and results of the decontamination demonstrations carried out at the schools.

Journal Articles

Decontamination of outdoor school swimming pools in Fukushima after the nuclear accident in March 2011

Saegusa, Jun; Kurikami, Hiroshi; Yasuda, Ryo; Kurihara, Kazuo; Arai, Shigeki; Kuroki, Ryota; Matsuhashi, Shimpei; Ozawa, Takashi; Goto, Hiroaki; Takano, Takao; et al.

Health Physics, 104(3), p.243 - 250, 2013/03

 Times Cited Count:3 Percentile:29.69(Environmental Sciences)

After the Nuclear accident on March 2011, water discharge from many outdoor swimming pools in the Fukushima prefecture was suspended out of concern that radiocesium in the pool water would flow into farmlands. We have reviewed the existing flocculation method for decontaminating pool water and established a practical decontamination method by demonstrating the process at several pools in the Fukushima prefecture.

Journal Articles

Impression on the 45th annual meeting of the Japan Health Physics Society

Saegusa, Jun

Isotope News, (703), p.34 - 35, 2012/11

General outline and personal impression on the 45th annual meeting of the Japan Health Physics Society, held at 16-17 June 2012, were summarized.

JAEA Reports

Guide for decontaminating swimming pool at schools

Matsuhashi, Shimpei; Kurikami, Hiroshi; Yasuda, Ryo; Takano, Takao; Seko, Noriaki; Naganawa, Hirochika; Kuroki, Ryota; Saegusa, Jun

JAEA-Testing 2011-007, 189 Pages, 2012/07

JAEA-Testing-2011-007.pdf:46.74MB

Because of TEPCO Fukushima Dai-ichi Nuclear Power Plant accident due to the Great East Japan Earthquake, a huge amount of radioactive materials was widely dispersed and precipitated into the environment. Swimming pools in Fukushima prefectures were contaminated with the radioactives. We JAEA carried out several demonstration tests to decontaminate the radioactives and discharge the pool water safely. We concluded the results obtained from the tests as "Guide for decontaminating swimming pool at school" and released it quickly. Following this, we also released the guide in English. This manuscript, as an experimental report of the swimming pool water decontamination, is consisted from the guide in Japanese and English prepared.

JAEA Reports

Emergency monitoring of environmental radiation and atmospheric radionuclides at Nuclear Science Research Institute, JAEA following the accident of Fukushima Daiichi Nuclear Power Plant

Okura, Takehisa; Oishi, Tetsuya; Taki, Mitsumasa; Shibanuma, Yukio; Kikuchi, Masamitsu; Akino, Hitoshi; Kikuta, Yasuaki; Kawasaki, Masatsugu; Saegusa, Jun; Tsutsumi, Masahiro; et al.

JAEA-Data/Code 2012-010, 37 Pages, 2012/05

JAEA-Data-Code-2012-010.pdf:2.28MB

Due to the accident at Fukushima Daiichi Nuclear Power Plant caused by the 2011 off the Pacific coast of Tohoku Earthquake occurred at 11th March 2011, the emergency environmental radiation monitoring was conducted at Nuclear Science Research Institute, Japan Atomic Energy Agency (JAEA). This report provides the monitoring results of ambient $$gamma$$-ray dose rate and atmospheric radioactivity concentration until the beginning of June 2011. Some anthropogenic radionuclides such as Cs-134, Cs-137, I-131, I-132, Te-132, Xe-133 and others were detected from air samples. The atmospheric radioactivity concentrations varied with some peaks corresponded with that of ambient $$gamma$$-ray dose rate after 15th March 2011. Composition of each peak showed various characteristic. Internal exposure caused by inhalation was estimated from the observed atmospheric radioactivity.

Journal Articles

Development of the quasi-monoenergetic neutron calibration fields of several tens of MeV at TIARA

Shikaze, Yoshiaki; Tanimura, Yoshihiko; Saegusa, Jun; Tsutsumi, Masahiro; Uchita, Yoshiaki; Yoshizawa, Michio

Progress in Nuclear Science and Technology (Internet), 1, p.166 - 169, 2011/02

For the reliable dose evaluation in high intensity proton accelerator facilities such as J-PARC, high energy neutron calibration fields above 20 MeV to evaluate energy response of both the monitors and the dosimeters used there, are required. Therefore, development of three neutron calibration fields of 45, 60 and 75 MeV has been in progress at TIARA of JAEA-Takasaki. Evaluation of the neutron fluence and establishment of the monitoring technique are important for the development of the calibration fields. Here, results of the fluence evaluation in the absolute measurement by using proton recoil counter telescope with high detection efficiency, a transmission type neutron fluence monitor newly developed to monitor neutron beam directly and its performance will be reported.

114 (Records 1-20 displayed on this page)