Commissioning of X-ray micro beam by Kirkpatrick-Baez (KB) mirror

Tanida, Hajime; Tsuji, Takuya; Kobata, Masaaki

JAEA-Technology 2021-031, 25 Pages, 2022/02

JAEA-Technology-2021-031.pdf:2.3MB

In the decommissioning of the Tokyo Electric Power Company Holdings Fukushima Daiichi Nuclear Power Station, analysis of fuel debris to understand its characteristics is very important. The fuel debris removed for testing and analyzing will be fine particulates. Non-destructive analytical methods using X-rays are effective for such samples, but in order to apply them to fine particles, the X-rays must be focused to the micrometer order. For this purpose, the Kirkpatrick-Baez (KB) mirror was introduced. In this paper, we record the selection, specification, adjustment of the mirror, and write down the example of mapping of elements and evaluation of their valence by this mirror.

Rapid collection of iron hydroxide for determination of Th isotopes in seawater

Okubo, Ayako; Obata, Hajime*; Magara, Masaaki; Kimura, Takaumi; Ogawa, Hiroshi*

Analytica Chimica Acta, 804, p.120 - 125, 2013/12

https://doi.org/10.1016/j.aca.2013.10.004

This work introduces a novel method of recovery of iron hydroxide using a DIAION CR-20 chelating resin column to determine Th isotopes in seawater with a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). Thorium isotopes in seawater were coprecipitated with iron hydroxide, and this precipitate was sent to chelating resin column. The chelating column quantitatively collected Th with iron hydroxide in seawater at flow rates of 20-25 mL/min. Based on this flow rate, a 5 L sample was processed within 3-4 h.

Th and Th distributions in mid-latitudes of the North Pacific Ocean; Effect of bottom scavenging

Okubo, Ayako; Obata, Hajime*; Gamo, Toshitaka*; Yamada, Masatoshi*

Earth and Planetary Science Letters, 339-340, p.139 - 150, 2012/07

https://doi.org/10.1016/j.epsl.2012.05.012

Vertical distributions of total Th and dissolved Th were determined in the mid-latitudes of the North Pacific Ocean. Th in the Pacific Ocean have been described well using the reversible-scavenging model. However, we observed the depletion of total Th. The enhanced vertical eddy diffusion derived from the complex topography of the western Pacific Ocean might promote bottom scavenging and transport of the low Th in deep water to the upper layers.

None

Kobayashi, Toru; Kobata, Masaaki; Tanida, Hajime; Fujimori, Shinichi; Tsuji, Takuya; Fukuda, Tatsuo; Shibata, Goro; Kawasaki, Ikuto; Matsuda, Shohei; Doi, Reisuke; et al.

no journal, , 

no abstracts in English

Iodine speciation and iodine-129 distribution in the Chukchi Sea and Bering Sea

Obata, Hajime*; Miwa, Kazuji*; Kondo, Yoshiko*; Gamo, Toshitaka*; Otosaka, Shigeyoshi; Suzuki, Takashi

no journal, , 

Distributions chemical species of iodine (iodide, iodate and organic iodine) in seawater were investigated in the Chukchi Sea and Bering Sea, Arctic northern marginal seas. I, which is a good tracer for anthropogenically released iodine to the marine environments, were also revealed by this study. Iodide concentrations in seawater often increased toward the seafloor. This tendency was remarkable with iodide and organic iodine, indicating that these iodine species are released from the sediments of the continental shelf. Concentrations of I ranged from 0.79 to 2.8910 atom/L. While this level was several times higher than those in the North Pacific, significant increase of I concentration due to seawater inflow from the North Atlantic was not observed. Considering latitudinal range of this study area, it can be estimated that most I detected by this study was derived by atmospheric deposition of I originates from Europe.

Status and future of radiocesium in the seafloor off Fukushima

Otosaka, Shigeyoshi*; Aono, Tatsuo*; Fukuda, Miho*; Kambayashi, Shota*; Misono, Toshiharu; Dohi, Terumi; Tsuruta, Tadahiko; Suzuki, Takashi; Takahashi, Yoshio*; Sugihara, Naoko*; et al.

no journal, , 

While the amount of cesium-137 (Cs: half-life 30.1 years) accumulated on the seabed due to the accident of the Fukushima Daiichi Nuclear Power Plant (0.1-0.2 PBq) is only about 1 to 2% of the total amount of Cs transported to the ocean, it has been reported that it will remain for a long time in the coastal areas. On the other hand, long-term migration process of the sedimentary radiocesium and the impact on the ecosystem near the seafloor remain unknown. In this presentation, we will give an overview of the distribution and behavior of Cs, especially on the seafloor along the coast of Fukushima, and report the latest results on the processes I the seafloor that should be considered on decadal timescale.

X-ray analysis for radioactive particulates from Fukushima-Daiichi Nuclear Power Plant using synchrotron radiation at SPring-8

Kobayashi, Toru; Kobata, Masaaki; Tanida, Hajime; Fujimori, Shinichi; Tsuji, Takuya; Fukuda, Tatsuo; Shibata, Goro; Kawasaki, Ikuto; Doi, Reisuke; Okamoto, Yoshihiro; et al.

no journal, , 

Study of gas adsorption on the surface of NEG materials by HAXPES

Kobata, Masaaki; Morohashi, Yuko; Abe, Kazuhide; Yamada, Ippei; Fukuda, Tatsuo; Koarai, Kazuma; Tanida, Hajime; Kamiya, Junichiro

no journal, , 

This study aimed to improve non-evaporable getter (NEG) coating technology on titanium substrates, focusing on lowering activation temperatures and enhancing repeatability. Using Hard X-ray Photoelectron Spectroscopy (HAXPES) and Secondary Ion Mass Spectrometry (SIMS), we analyzed NEG activation and degradation mechanisms. The effects of titanium, stainless steel (SUS316), and beryllium copper (BeCu) substrates on NEG properties were compared. Results suggested that the BeCu substrate had the lowest activation temperature, indicating its potential advantage for low-temperature NEG activation.

Distribution and source of I-129 in Chukchi Sea and Bering Sea

Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi; Otosaka, Shigeyoshi

no journal, , 

I-129 in a global environment is originated from the European nuclear fuel reprocessing plants (NFRP), Sellafield in U.K. and La Hague in France, and it is observed a large amount of I-129 inflows from European NFRP into the eastern and central Arctic Ocean. Previous studies on I-129 at surface indicated seawater with high I-129 concentration does not inflow from eastern and central Arctic Ocean to Chukchi Sea, located in western Arctic Ocean. However, there is a possibility of inflow of I-129 because the vertical distribution of I-129 has not observed at the ocean. The purpose of this study is to identify the inflow of seawater with high I-129 concentration from eastern and central Arctic Ocean by observing the vertical distribution of I-129 and water mass structure in Chukchi Sea and Bering Sea. Seawater with high temperature at surface of southern Chukchi Sea (- 66N) and with low temperature at bottom of the northern Chukchi Sea (69N -) were observed. The seawater with low temperature might include high I-129 concentration. However, I-129 concentration in some points was observed ranging from 0.79 to 2.89 (10 atoms/L), which was two orders of magnitude lower than that in the eastern and central Arctic Ocean. And no significant difference of I-129 concentration between seawater at surface and at bottom was shown. Therefore, we could not identify the inflow of seawater with high I-129 concentration from eastern and central Arctic Ocean to Chukchi Sea.

Direct energy conversion using Pt/GaO Schottky junction from gamma ray region

Fukuda, Tatsuo; Fukada, Yukimasa; Kobata, Masaaki; Yoshii, Kenji; Shobu, Takahisa; Tominaga, Aki; Yamashita, Yoshiyuki*; Tanida, Hajime; Yaita, Tsuyoshi

no journal, , 

no abstracts in English