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.

Rapid collection of iron hydroxiedes for determination of Th isotopes in seawater using polyamin type chelating resin

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

no journal, , 

This work introduces a novel method of recovery of iron hydroxide with thorium 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 co-precipitated with iron hydroxide, and this precipitate was sent to chelating resin column. The chelating column quantitatively collect Th with iron hydroxide in seawater at flow rate of 20-25 mL/min. Based on this flow rate, 5 L sample was processed within 3-4 h. The aging of iron hydroxide tends to reduce the recovery of Th. The rapid collection method was successfully applied to the determination of Th and Th in open-ocean seawater samples.

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.

Hard X-ray photoelectron spectroscopy study of radiation effects of Pt/YFeO

Kobata, Masaaki; Yoshii, Kenji; Fukuda, Tatsuo; Kawasaki, Ikuto; Satou, Yukihiko; Tanida, Hajime; Okane, Tetsuo; Yamagami, Hiroshi; Yaita, Tsuyoshi; Harii, Kazuya; et al.

no journal, , 

We have investigated the electronic structures of Pt/YFeO thin films irradiated by gamma ray and heavy particles. Investigating details of this system is interesting from a possible application of waste heat recovery using the spin Seebeck effect (SSE) due to a tolerance against a presence of atomic defect. Irradiation of Co gamma ray does not affect the spectral profiles such as Fe 2, a fact being consistent with the gamma-ray tolerance of SSE as reported previously. On the other hand, the irradiation of Au particles was found to lead to a chemical shift of some photoelectron peaks, suggesting a possible defect of some ions such as Fe.

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.

Development of microbeam system at SPring-8 JAEA beamline BL22XU

Tanida, Hajime; Tsuji, Takuya; Kobata, Masaaki; Kitagaki, Toru

no journal, , 

In the decommissioning of Fukushima Daiichi Nuclear Power Plant, analysis of fuel debris is extremely important to understand its properties. The fuel debris to be removed on a trial basis and the samples available for analysis are expected to be fine particles. In the case of relatively large samples, handling becomes difficult due to the dose problem. Non-destructive X-ray analysis using X-rays is an effective analysis method for such samples, but in order to apply it to fine particles, X-rays must be focused to the micrometer order. For this purpose, a Kirkpatrick-Baez (KB) mirror was installed in the experimental hutch 3 of the RI building of the JAEA beamline BL22XU, which has a hard X-ray undulator as a light source, at SPring-8.

Study of NEG surface reaction with gas molecules by in-situ HAXPES

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

no journal, , 

The mechanism of how the substrate titanium contributes to the advanced getter performance has not been elucidated. In this study, NEG/Ti interface analysis was performed using HAXPES at BL22XU to clarify the effect of Ti substrate on NEG performance.