Preliminary missions for the decommissioning of the laboratory building No.1 for the plutonium research program

Segawa, Yukari; Horita, Takuma; Kitatsuji, Yoshihiro; Kumagai, Yuta; Aoyagi, Noboru; Nakada, Masami; Otobe, Haruyoshi; Tamura, Yukito*; Okamoto, Hisato; Otomo, Takashi; et al.

JAEA-Technology 2016-039, 64 Pages, 2017/03

JAEA-Technology-2016-039.pdf:5.24MB

The laboratory building No.1 for the plutonium research program (Bldg. Pu1) was chosen as one of the facilities to decommission by Japan Atomic Energy Agency Reform in September, 2013. The research groups, users of Bldg. Pu1, were driven by necessity to remove used equipment and transport nuclear fuel to other facilities from Bldg. Pu1. Research Group for Radiochemistry proactively established the Used Equipment Removal Team for the smooth operation of the removal in April, 2015. The team classified six types of work into the nature of the operation, removal of used equipment, disposal of chemicals, stabilization of mercury, stabilization of nuclear fuel, transportation of nuclear fuel and radioisotope, and survey of contamination status inside the glove boxes. These works were completed in December, 2015. This report circumstantially shows six works process, with the exception of the approval of the changes on the usage of nuclear fuel in Bldg. Pu1 to help prospective decommission.

Elucidation on the desorption of Cs from marine soil

Segawa, Yukari; Kumagai, Yuta; Watanabe, Masayuki; Otosaka, Shigeyoshi; Kobayashi, Takuya

no journal, , 

Cesium (Cs) is strongly adsorbed on the sea soil, so that it is reasonably considered that the elution of Cs by desorption has not been occurred. However, by the environmental survey of radioactivity after the Fukushima Dai-ichi Nuclear Power Plant accident, radioactive Cs in sea soil has been constantly decreased for these five years. This result possibly suggests that the transition of Cs is caused by continuous elution or suspension. In order to predict the transition behavior of Cs more accurately over a long period of time, it is important to elucidate the desorption process of Cs from the sea soil. So we made a new apparatus for observing the only desorption process of Cs a long period of time.

Radiation-induced degradation of 2-chlorophenol in mixture of zeolite and water

Kumagai, Yuta; Sugawara, Atsushi; Segawa, Yukari; Watanabe, Masayuki

no journal, , 

Nanoscale porous structure of zeolites provides attractive environment for radiation-induced reactions. Efficiency of the reactions potentially improves owing to high yields of reactive radicals inside the pores, which would lead to an application of ionizing radiation for decomposition of organic substances of concern. Hence, this study examined degradation of a chlorinated organic compound, 2-chlorophenol (2-ClPh), as a model compound in aqueous solution by the combined use of gamma irradiation and adsorption by zeolite. Degradation efficiency of 2-ClPh by irradiation was improved when a hydrophobic zeolite was used as adsorbent. On the other hand, a hydrophilic zeolite showed an insignificant effect on the degradation efficiency. The difference between these zeolites is expected to be due to different performances for adsorption of 2-ClPh. The results indicate that degradation of aqueous organics can be promoted by the use of zeolites having high performance for adsorption.