Experiences in dismantlement of gloveboxes for wet recovery and other use that are contaminated with nuclear fuel materials

Kitamura, Akihiro; Hirano, Hiroshi*; Yoshida, Masato; Takeuchi, Kentaro

Hoken Butsuri (Internet), 58(2), p.76 - 90, 2023/08

https://doi.org/10.5453/jhps.58.76

The alpha contaminated gloveboxes have been dismantled for over 20 years in Plutonium Fuel Fabrication Facility. The so called wet recovery equipment gloveboxes, which recover plutonium and uranium from scrap fuel by dissolving and extracting processes, were chosen as the priority gloveboxes to be dismantled. These gloveboxes and other gloveboxes in the same room were size reduced and removed up until 2022. Also, non-radioactive ancillary facility and non-radioactive giant glovebox were removed from 2007 to 2010 for ease of glovebox dismantling activities that follows and for making waste storage spaces. Several incidents were occurred and recidivism prevention measures were implemented on each occasion. In this report, glovebox dismantling activities we conducted in the past 20 years are reviewed and lessons we have learned are summarized.

New decontamination technique for forests with interpolyelectrolyte complex and bentonite

Nagasu, Ryosuke*; Yoshida, Masafuyu*; Naganawa, Hirochika; Yanase, Nobuyuki; Nagano, Tetsushi; Mitamura, Hisayoshi; Komatsuzaki, Shoichi*; Kumazawa, Noriyuki*

no journal, , 

A new method for easily removing of radioactive cesium from muck soil in forests has been developed. Fine particles of bentonite having negative charge and high adsorbing ability for cesium can effectively adsorb radioactive cesium, and then, the bentonite fine particles can aggregate and being trapped by interaction with interpolyelectrolyte complex having positive charge, which enables an easy removal of radioactive cesium from muck soil in forests.

Status of decommissioning of the Plutonium Fuel Fabrication Facility, PFFF, and R&Ds of dismantling methods for glove boxes

Yoshida, Masato

no journal, , 

no abstracts in English

R&Ds of dismantling methods for glove boxes; Development of bag-out technology for large-size equipment

Yoshida, Masato

no journal, , 

no abstracts in English

Development of elemental technologies for "in-situ" alpha dust monitors for fuel debris retrieval and decommissioning

Tsubota, Yoichi; Yoshida, Masato; Honda, Fumiya; Tokonami, Shinji*; Nakagawa, Takahiro; Kawasaki, Takashi

no journal, , 

In order to measure the airborne concentration in air in real time, a dust monitor to measure directly the alpha-particle concentration in a flat-type flow path was developed and its performance was evaluated. The performance of the prototype dust monitor was evaluated in a high-humidity environment, and its counting rate was more than ten times higher than that of a conventional dust monitor.

Improvement of storage cans for radioactive solid wastes and examination of their internal pressure inspection methods

Nagai, Yuya; Yoshida, Masato

no journal, , 

no abstracts in English

Improvement of alpha aerosol monitor for in-situ measurement of airborne radioactive concentration in decommissioning

Tsubota, Yoichi; Honda, Fumiya; Yoshida, Masato; Nakagawa, Takahiro; Tamakuma, Yuki*; Tokonami, Shinji*; Ikeda, Atsushi

no journal, , 

A large amount of radioactive aerosols are expected to be dispersed fuel during debris cutting during large-scale retrieval of fuel debris at the Fukushima Daiichi Nuclear Power Plant (1F) and dismantling of nuclear fuel attachments during decommissioning of nuclear fuel facilities. Particulates containing -nuclides (-aerosols) in particular have very high effective dose coefficients upon inhalation, therefore appropriate control and measurements are required. Conventional dust monitors using SSBD have difficulties with moisture resistance, noise resistance, and clogging of filter paper. We have designed and prototyped an -aerosol monitor that directly measures -rays from aerosols using a scintillator and a multi-channel photomultiplier tube after drying the aerosols by heating the flat channel inlet without using a collecting filter paper in order to realize monitoring near the point where highly concentrated -aerosols are generated. In this presentation, we report on the results of basic performance evaluations, the change in particle size due to air drying, and the improvement of the power supply method of the detection unit for on-site implementation at 1F.

物品搬出入システム及び物品搬出入方法

吉田 将冬; 周治 愛之; 川崎 猛; 木村 泰久; 平野 宏志

not registered

JP, 2018-170691  Patent licensing information  Patent publication (In Japanese)

【課題】汚染雰囲気に曝される物を最小限に抑えて、汚染雰囲気に対して物品を安全に搬出入可能な物品搬出入システムを提供する。 【解決手段】物品搬出入システムは、汚染雰囲気を囲って非汚染雰囲気から隔離すると共に、汚染雰囲気及び非汚染雰囲気を連通させる開口が形成されたポートを有する建屋と、物品が載置される載置部、及び把持可能な把持部を有する載置台と、可撓性を有する材料で構成されており、開放された両端部のうち、一方側端部が前記開口を囲むようにポートに接続され、他方側端部が載置部を囲むように載置台に接続される筒状部材と、筒状部材から露出した把持部を把持して、ポートを通じて載置台を建屋に搬入し、さらに建屋から搬出する搬出入装置と、載置台が建屋から搬出された後に、ポートと載置台との間で筒状部材をシールするシール装置とを備えることを特徴とする。

ポートキャップ及びグローブボックス

木村 泰久; 平野 宏志; 柴沼 智博; 吉田 将冬; 永井 佑哉; 塙 幸雄; 周治 愛之; 會田 貴洋

南 明則*

JP, 2020-069715  Patent licensing information  Patent publication (In Japanese)

【課題】ポート本体とグローブとを間に隙間が生じるのを適切に防止できるポートキャップを提供する。 【解決手段】ポートキャップ(20)は、取付開口(8)から突出する筒体(16)と、先端部が筒体(16)を通じてグローブボックスの内部空間に進入し、基端部が筒体(16)の外周面側に折り返されたグローブ(12)と、折り返されたグローブ(12)と筒体(16)の外周面との間を封止するOリング(13A,13B)及びクランプリング(14)とを備えるグローブポート(10)に取り付けられ、グローブ(12)の内側から筒体(16)に圧入される内筒(21)と、筒体(16)の外側を覆う外筒(22)と、内筒(21)及び外筒(22)の端部同士を接続するフランジ(23)とを備え、内筒(21)の外周面側の先端(21A)は、R面取りされている。