Sun Eui Lee, Yuji Hatano, Masanori Hara, Suguru Masuzaki

Abstract
A special experimental setup was designed and constructed to perform simultaneous multipoint measurements of β-ray induced X-ray spectra for non-destructive depth profiling of tritium in plasma-facing tiles retrieved from fusion devices. The setup consists of compact silicon drift detector and an airtight acrylic chamber. The plasmafacing graphite tiles used in the deuterium experiment of Large Helical Device (LHD) in National Institute for Fusion Science (NIFS) were examined. The obtained X-ray spectra were simulated using Monte Carlo simulation tool kit Geant4. It has been found that tritium penetrated beyond the carbon deposition layer.

Satoshi Akamaru, Yasuyuki Horai, Akira Taguchi, Masanori Hara

Abstract
We investigated applicability of solid phosphor nanoparticles to radioactivity measurements by using a liquid scintillation counter. Stable water-suspendable ZnS:Cu,Cl phosphor nanoparticles was prepared to follow the literature. The prepared ZnS:Cu,Cl was dispersed into tritiated water, and its radioluminescence was counted by photomultiplier tube. The ZnS:Cu,Cl nanoparticles emitted photon by irradiation of tritium β- ray in tritiated water. The number of emitted photons increased proportionally with the tritium concentration in the sample, indicating that the tritium concentration in solution could be measured by using ZnS:Cu,Cl nanoparticles. The photon counting through the universal coincident circuit was also performed in order to reduce background noise. The lower detection limit was not improved by using the universal coincident circuit, while the emitted photons were counted for either photomultiplier. The result suggested that the concentration of ZnS:Cu,Cl nanoparticles should be optimized. I

Akira Taguchi, Yuki Yoneyama

Abstract
Fe₃C supported on iron grains (Fe₃C/Fe) was prepared by the solid-solid reaction of iron grains (Fe-pw) and carbon that had been sputter deposited on the Fe-pw surface. Fe₃C/Fe showed slightly higher methane decomposition activity as compared to the bare Fe-pw at 750 ºC.

Hidehisa Hagiwara, Ittoku Nozawa, Katsuaki Hayakawa

Abstract
CaTa₂O₇:Bi nanosheet (BCT-NS) was prepared from aurivillius-structured Bi₂CaTa₂O₉ (BCT) by protonation and exfoliation treatment. By treating BCT with hydrochloric acid, Bi₂O₂ layer in BCT was dissolved, and the amount of Bi was further decreased during the exfoliation treatment. From an EDX analysis, the doping concentration of Bi in BCT-NS was determined about 0.3 mol%. With excitation 310 nm, broad photoluminescence band peaking at 500 nm was observed in the range of 450-650 nm. Fluorescence lifetime measurement monitored at 430, 470, and 530 nm revealed that a single type of Bi luminescence center exists in BCT-NS.

Masanori HARA, Masato NAKAYAMA, Satoshi AKAMARU, Miki SHOJI, Yutaro TSUCHIYA, Yoshinari OSHIMI, Takuyo YASUAMATSU

Abstract
In liquid scintillation counting, a preparation of adequate scintillation cocktail is an essential to obtain an accurate activity of sample and reproducible data. The adequate scintillation cocktail needs to be a homogeneous and colorless liquid phase. In this study, various cocktails with various volume ratios of sample to liquid scintillator were prepared to examine their homogeneity and color. Both Ultima Gold LLT and Ecoscinti Ultra held water sample above 45 % of cocktail volume with no phase separation and clear liquid. For 1 mol/L sodium hydroxide solution, both scintillators showed the phase separation at sample fraction of less than 15 %. For acid solutions such as hydrochloric acid and nitric acid, the phase separations appeared at less than 26 % of cocktail volume in both scintillators. The quenching index, ESCR, of cocktails were measured to estimate the lower limit of detection. For water and sea water samples, the lower limit of detection was improved with adding sample up to 45 % of cocktail volume.