Field test around Fukushima Daiichi Nuclear Power Plant site using improved Ce:Gd(Al,Ga)O scintillator Compton camera mounted on an unmanned helicopter

Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.

Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12

https://doi.org/10.1080/00223131.2016.1185980

The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 44 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the -ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10).

Neutron irradiation effect of high-density MoO pellets for Mo-99 production

Nishikata, Kaori; Ishida, Takuya; Yonekawa, Minoru; Kato, Yoshiaki; Kurosawa, Makoto; Kimura, Akihiro; Matsui, Yoshinori; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

KURRI Progress Report 2013, P. 242, 2014/10

As one of effective applications of the Japan Materials Testing Reactor (JMTR), JAEA has a plan to produce Mo-99 (Mo) by (n,) method ((n,)Mo production), a parent nuclide of Tc. In this study, preliminary irradiation tests were carried out with the high-density MoO pellets in the KUR and the Mo production amount was evaluated between the calculation results and measurement results.

Renewal of monitoring boards in control room at the hot laboratory

Kurosawa, Makoto; Kato, Yoshiaki; Yonekawa, Minoru; Taguchi, Taketoshi

UTNL-R-0486, p.9_1 - 9_11, 2014/03

It has been irradiated in the concrete cell, the microscope lead cell, the lead cell for materials examinations and the iron cell and, in the JMTR Hot Laboratory Facilities, examines it after the irradiation such as fuel and nuclear reactor structure materials. I install a monitoring board for a concrete cell, a microscope lead cell, a lead cell for materials examinations and iron cells in the control room I watch concentration such as the minus number pressure in these each cell, the air absorption dose rate in the cell, the cover door opening and shutting indication and to control it. As for these monitoring boards, about 30 through 40 or more passed after an in-service start, and high aging decided to update it in consideration of the driving of approximately 20 years after JMTR re-operation because trouble by becoming it and outbreak of the malfunction were concerned about.

Durability test of geomembrane liners presumed to avail near surface disposal facilities for Low-level waste generated from research, Industrial and Medical facilities

Nakata, Hisakazu; Amazawa, Hiroya; Sakai, Akihiro; Kurosawa, Ryohei; Kanno, Naohiro*; Kashima, Takahiro*; Sakamoto, Yoshiaki

JAEA-Technology 2013-036, 47 Pages, 2014/02

JAEA-Technology-2013-036.pdf:5.27MB

The Low-level Radioactive Waste Disposal Project Center will construct near surface disposal facilities. The disposal facilities consist of concrete pit type for low-level radioactive wastes and trench type for very low level radioactive wastes. As for the trench type disposal facility, two kinds of facility designs are on projects -one for normal trench type disposal facilities and the other for trench type disposal facilities with geomembrane liners that could prevent from causing environmental effects of non radioactive toxic materials. This study examined mechanical strength and permeability properties to assess the durability on the basis of an indoor accelerated exposure experiment targeting the liner materials presumed to avail the conceptual design so far. Its results will be used for the basic and detailed design henceforth by confirming the empirical degradation characteristic with the progress of the exposure time.

Conceptual design of near surface disposal facilities of radioactive wastes generated from research, industrial and medical facilities

Amazawa, Hiroya; Sakai, Akihiro; Nakata, Hisakazu; Hara, Hironori; Kurosawa, Ryohei; Yamamoto, Masayuki*; Kawata, Yosuke*; Sakamoto, Yoshiaki

JAEA-Technology 2012-031, 338 Pages, 2012/10

JAEA-Technology-2012-031.pdf:19.43MB

JAEA is responsible for siting a proper location to establish new disposal facilities with siting criterion and procedure, in consideration of transparency and impartial for the siting process, based on Plan Concerning the Disposal Business Execution. As a part of the study to draw up siting criterion and procedure, Sensitivity analysis of the disposal facilities from the viewpoint of dose evaluation and cost estimation under various siting condition will be carried out. Therefore, Conceptual design of disposal facilities as a reference case is necessary. The basic condition of the design conforms to the property, quantity, radioactivity of waste packages, technical standards and likely siting condition. This report summarizes the results of the reasonable design of our disposal facilities and the layout of the place of activity where the disposal facilities and associated facilities to be installed.

Recent status of research activities for development of CTBT-related technologies in JAERI

Hirota, Naoki*; Hokida, Takanori; Inoue, Yoji; Kumata, Masahiro; Kurosawa, Yoshiaki; Miyamoto, Yutaka; Nakahara, Yoshinori; Oda, Tetsuzo; Shinohara, Nobuo; Uchikoshi, Takako*; et al.

JAERI-Review 2003-021, 68 Pages, 2003/08

JAERI-Review-2003-021.pdf:9.73MB

This report describes research activities of the R & D Group for Non-Proliferation Technology related to the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification regime. The main subjects of this report are (1) an overview of the CTBT verification regime, (2) preparation of the National Data Center for radionuclide data, (3) construction and operation of the radionuclide monitoring stations at Takasaki and Okinawa and the certified rarionuclide laboratory at Tokai in Japan. We have participated in an intercomparison test internationally organized for the certified laboratories and the test results are given here. Scientific application of the CTBT-related technologies to environmental researches is also depicted.

Replacement of pressure surge tank and vent valves in JMTR

Ishii, Toshimitsu; Ooka, Norikazu; Saito, Junichi; Kobayashi, Shunichi; Takahashi, Kunihiro; Tsukada, Takashi; Iwai, Takashi; Kurosawa, Yoshiaki; Hoshiya, Taiji; Tsuji, Hirokazu

Proceedings of International Symposium on Case Histories on Integrity and Failures in Industry (CHIFI), p.227 - 236, 1999/00

no abstracts in English

Fabrication technique development of high-density MoO pellets for Mo/ Tc production

Nishikata, Kaori; Kimura, Akihiro; Kato, Yoshiaki; Kurosawa, Makoto; Ishida, Takuya; Tsuchiya, Kunihiko; Kakei, Sadanori*; Yoshinaga, Hideo*; Niizeki, Tomotake*; Hasegawa, Yoshio*

no journal, , 

no abstracts in English

Interference removal for high-sensitivity rapid analysis of Pd in radioactive rubbles by ICP-MS/MS

Iwahashi, Hiroyuki; Do, V. K.; Furuse, Takahiro; Ota, Yuki; Homma, Shunta; Kurosawa, Kiyoko*; Motoki, Yoshiaki*; Hirosawa, Takashi

no journal, , 

The radiometric determination of beta emitting Pd (half-life of 6.5 million years) requires a multiple-step chemical separation and a time-consuming radioactive measurement. Inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with recent technological advances in interference removal by two quadrupole mass filters and a collision/reaction cell could be an alternative for highly sensitive analysis of long-lived radionuclides. In this study, we have developed an analytical method for the determination of Pd in concrete rubble by ICP-MS/MS combined with single-column chromatographic separation. A simplified procedure for the separation of Pd from concrete matrices was developed. The measurement condition was optimized to completely suppress the interference including the isobar Ag and the sample matrices. The application of the developed method to radioactive concrete rubble is under consideration.

Evaluation of infiltration water through the upper cover soil in trench type disposal facility for low level radioactive wastes generated from research, industrial and medical facilities

Kurosawa, Ryohei; Sakai, Akihiro; Nakata, Hisakazu; Amazawa, Hiroya; Sakamoto, Yoshiaki

no journal, , 

In the safety assessment for the trench disposal facilities, outflow of radioactive material to the environment is assumed to be due to the percolating rain water into the waste layer, because the waste layer is established above the groundwater level. Therefore, in dose assessment of trench type disposal facilities, it is important to evaluate the effect of facility designs that suppresses the amount of water infiltration to the waste layer due to rainfall. Therefore, using the weather conditions in Japan, and evaluated the penetration water into the upper cover soil in trench type disposal facility other than the surface runoff and evapotranspiration. The evaluation was carried out of the water penetration leading to waste layer by migrating the upper cover soil fitted with a water barrier sheet or low-permeable layer soil layer of in trench type disposal facility. As evaluation result, by the influence of vegetation state of the upper cover soil surface, it was found that the amount of water from about 0.2 times to 0.7 times the precipitation have infiltrated to the upper cover soil. By setting the value corresponding to the clay hydraulic conductivity of low permeability soil layer, penetration amount of water to the waste layer from the top upper cover soil, it has been found that it is possible to reduce the penetration amount of water to the upper cover soil from the rain.