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Journal Articles

Frontline of R&D for decommissioning and waste disposal, 1; R&D for processing and disposal of low-level radioactive waste and closure of uranium mine

Tsuji, Tomoyuki; Sugitsue, Noritake; Sato, Fuminori; Matsushima, Ryotatsu; Kataoka, Shoji; Okada, Shota; Sasaki, Toshiki; Inoue, Junya

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 62(11), p.658 - 663, 2020/11

no abstracts in English

Journal Articles

Investigation of the contamination on the operation floor of unit 2 based on the radiochemical analysis data

Takahatake, Yoko; Koma, Yoshikazu

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

JAEA Reports

Restoration activity of the contamination accident at plutonium fuel research facility

Restoration Activity Team for the PFRF Contamination Incident

JAEA-Review 2019-001, 58 Pages, 2019/03

JAEA-Review-2019-001.pdf:10.74MB

The contamination accident occurred in a laboratory room (Room No.108) of Plutonium Fuel Research Facility (PFRF) in Japan Atomic Energy Agency (JAEA), Oarai Research and Development Institute on June 6, 2017. The polyvinyl chloride (PVC) bags burst just after the lid of one storage container was opened during the inspection of storage containers for U and Pu in the ventilation hood. At that time, part of nuclear materials in the storage container were scattered all over the room. Five workers in the room were subjected to plutonium contamination, which resulted in internal exposure. In order to restore the Room No.108 of PFRF, the Restoration Activity Team organized in JAEA carried out the decontamination work after the investigation of the contamination level in the room. The team decontaminated the surface of walls, ceiling, gloveboxes and other experimental instruments. Depending on the contamination distribution and installation state of the instruments, suitable decontamination methods were selected. In addition to the manual wiping using wet clothes, the exfoliation method using a strippable paint was applied for constricted areas. As a result, the loose alpha-contamination level fell below the detection limit throughout the room. On the other hand, the fixed contamination was covered with plastic sheets after the decontamination by a strippable paint. We hope that the restoration activity described in this report will provide useful information for the management of decommissioning facilities, especially for facilities treating alpha-radioactive materials such as plutonium.

JAEA Reports

Treatment and decomposition of HLW-79Y-4T type transportation cask for liquid radioactive fuel material

Yamaguchi, Isoo*; Morita, Yasuji; Fujiwara, Takeshi; Yamagishi, Isao

JAERI-Tech 2005-054, 61 Pages, 2005/09

JAERI-Tech-2005-054.pdf:12.38MB

The HLW-79Y-4T type transportation cask for liquid radioactive fuel material (commonly called "Cendrillon") was imported from France and modified for Japanese regulation in order to obtain high-level radioactive liquid waste (HLW) for partitioning tests in JAERI by transportation from Tokai Establishment of Japan Nuclear Fuel Cycle Development Institute. The cask was used for the HLW transportation five times from 1982 to 1990. After that, it was kept and maintained for next transportation of HLW from facilities outside JAERI. Finally, we decided to decompose the cask because HLW can be obtained in JAERI Tokai. For the decomposition, radiation dose and contamination by radioactivity was first measured and then the methods to reduce those levels were determined. The cask was decomposed after the decontamination to separate the part that has high radiation level. The separated part was put in a vessel specially prepared. The present report describes those procedures for the decomposition of the transportation cask.

Journal Articles

New laser decontamination technique for radioactively contaminated metal surfaces using acid-bearing sodium silicate gel

Kameo, Yutaka; Nakashima, Mikio; Hirabayashi, Takakuni*

Journal of Nuclear Science and Technology, 41(9), p.919 - 924, 2004/09

 Times Cited Count:10 Percentile:57.38(Nuclear Science & Technology)

A new laser decontamination method utilizing a gel made from a sodium silicate solution and an acid was developed for removing radioactive nuclide incorporated into a surface oxide layer on metal waste. Decontamination tests were carried out using both simulated contaminated samples and pipe specimens cut from the primary coolant system of the Japan Power Demonstration Reactor. In the case of surface oxide layer consisting mainly of iron oxide, more than 99% of surface radioactivities were removed after two to three decontamination runs. In order to ascertain the role of laser irradiation on chemical reactions, chemical states of O and Fe in the oxide layer before and after decontamination were analyzed by X-ray photoelectron spectroscopy. It was found that the oxide layer was dissolved into the acid-containing gel, and the reaction was extensively promoted by the laser irradiation.

Journal Articles

Development of automated measurement device for low-level radioactive contamination on building surfaces

Tachibana, Mitsuo; Ito, Hirokuni*; Hatakeyama, Mutsuo*; Yanagihara, Satoshi

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.120 - 127, 2004/03

The RAPID-1600 was developed to measure a low-level radioactive contamination on building surfaces automatically. The double layered detectors are structured by two gas flow type detectors with a $$beta$$ rays shielding plate between the two detectors and it is horizontally positioned. The lower counter measures $$beta$$ and $$gamma$$ rays and the upper counter measures $$gamma$$ rays. The $$beta$$ rays counting rates are derived by subtracting $$gamma$$ rays counting rates of the upper counter from $$gamma$$ and $$beta$$ rays counting rates of the lower counter. This mechanism results in sensitive to $$beta$$ rays against to low background radiation conditions. The driving unit can move omnidirectionally by controlling two driving wheels individually, and has a capability to correct its position if an orbital error is detected by the self-position identification system. The RAPID-1600 was successfully applied to the actual measurement in the radioisotope production facilities. The RAPID-1600 is expected to be a useful tool for measurement of radioactivity in decommissioning nuclear facilities.

Journal Articles

Automatic measurement of low level contamination on concrete surfaces

Tachibana, Mitsuo; Ito, Hirokuni; Shimada, Taro; Yanagihara, Satoshi

Proceeding of International Waste Management Symposium 2002 (WM '02) (CD-ROM), 8 Pages, 2002/00

Automatic measurement of radioactivity is necessary for considering cost effectiveness in final radiological survey of building structures in decommissioning nuclear facilities. The RAPID (radiation measuring pilot device for surface contamination) was developed to be applied to automatic measurement of low level contamination on concrete surfaces. The RAPID has a capability to measure contamination with detection limit of 0.14 Bq/cm$$^{2}$$ for $$^{60}$$Co in 30 seconds of measurement time and its efficiency is evaluated to be 5 m$$^{2}$$/h in a normal measurement option. It was confirmed that low level contamination on concrete surfaces could be surveyed by the RAPID efficiently compared with direct measurement by workers through its actual application.

Journal Articles

Study on the measurements and evaluation of environmental external exposure after the nuclear accident

Sakamoto, Ryuichi; Saito, Kimiaki; Tsutsumi, Masahiro; Nagaoka, Toshi

Hoken Butsuri, 36(4), p.297 - 307, 2001/12

There are many factors which affect external exposure in contaminated area: distributions of fallout, compositions of radioactive nuclides, soil conditions, depth profile of radioactivity in soil, rain fall, snow cover, radioactive decay, shielding effects of houses and other structures, de-contamination measures, and the 'occupancy factor' which accounts for the fraction of time that inhabitants spend in different locations. In this study, several important issues concerning these factors have been investigated using field measurements and computational simulations since 1992 in the Chernobyl area. The objectives of the study were: (1) The development of a mobile survey method to collect radiation data of the contaminated area over a wide area in a short time; (2) The verification of a method to infer external doses to the population; (3) The provision of basic data used for the evaluation of external dose due to gamma ray using a Monte Carlo simulation method. (4) Characteristics of the radiation fields in contaminated area. In this report, the results were summerized.

Journal Articles

Development of computer systems for planning and management of reactor decommissioning

Yanagihara, Satoshi; Sukegawa, Takenori; Shiraishi, Kunio

Journal of Nuclear Science and Technology, 38(3), p.193 - 202, 2001/03

no abstracts in English

Journal Articles

Reactivity accident of nuclear submarine at Vladivostok

Takano, Makoto; Romanova, V.*; Yamazawa, Hiromi; Sivintsev, Y.*; Compton, K.*; Novikov, V.*; Parker, F.*

Journal of Nuclear Science and Technology, 38(2), p.143 - 157, 2001/02

no abstracts in English

Journal Articles

Evaluation of methodology on radioactive inventory estimation in the Japan power demonstration reactor decommissioning program

Sukegawa, Takenori; Hatakeyama, Mutsuo; Yanagihara, Satoshi

Journal of Nuclear Science and Technology, 37(Suppl.1), p.367 - 371, 2000/03

no abstracts in English

Journal Articles

Procedure for segregation of non-radioactive waste related to decommissioning nuclear facilities; Experiences on the Japan Power Demonstration Reactor dismantling

Tachibana, Mitsuo; Hatakeyama, Mutsuo; Yanagihara, Satoshi

Nihon Genshiryoku Gakkai-Shi, 41(6), p.677 - 685, 1999/00

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Journal Articles

Radiation protection in decontamination work of hot cells in reactor fuel examination facility

Sato, Nobuyuki; ; Kobayashi, Makoto; Nakazawa, Takashi; ; ; Ikezawa, Yoshio

Proc. of the Int. Conf. on Radiation Effects and Protection, p.440 - 445, 1992/00

no abstracts in English

Journal Articles

Action in radiation protection to new national radiological regulations; Practice in radiation control

Matsui, Hiroshi; Ikezawa, Yoshio

Firumu Bajji Nyusu, 0(161), p.7 - 10, 1990/05

no abstracts in English

Journal Articles

International Symposium on Recovery Operations in the Event of Nuclear Accident or Radiological Emergency

Ikezawa, Yoshio

Hoken Butsuri, 25(3), p.299 - 300, 1990/00

no abstracts in English

Journal Articles

Clothing in special environment; Nuclear environment

Murata, Mikio; *

Seni To Kogyo, 45(7), p.308 - 314, 1989/07

no abstracts in English

17 (Records 1-17 displayed on this page)
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