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Hirade, Tetsuya
no journal, ,
Radiation chemistry research on water is important in the fields of nuclear power and radiation effects. Studies on water using positron annihilation have been conducted on the behavior of excess electrons using the positronium formation process. It has become possible to study the behavior of OH radicals using the reaction of OH radicals and triplet positronium by positron annihilation age-momentum correlation (AMOC) measurement. From the temperature dependence of the behavior of excess electrons and OH radicals, it has become clear that structural changes in water affect the behavior of these active species. The detail of results will be introduced.
Oka, Toshitaka; Takahashi, Atsushi*; Mitsuyasu, Yusuke*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Yamashita, Takuma*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
Electron spin resonance (ESR) dosimetry technique is a powerful tool that has been used in the study of external exposure dose assessment of human by measuring CO
radicals of teeth. In this work, we applied this technique for wild monkey and wild racoon captured in Fukushima prefecture, and estimated the external exposure dose.
O; Stabilization of the matrix by forming UO solid solution phaseKumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*
no journal, ,
Possibility of the fuel debris degradation was investigated by using simulated fuel debris containing U, stainless steel elements, and Zr. The simulated debris samples were obtained by pyrochemical treatment under different conditions. The leaching tests of the samples were conducted and the samples were analyzed by Raman spectroscopy. By comparing the different simulated debris samples, we found that a simulated debris that contained UO solid solution phase as the major component was much more stable to HO than the other types of the simulated debris samples.
Taira, Yoshitaka*; Sugita, Kento*; Yamamoto, Ryohei*; Okano, Yasuaki*; Hirade, Tetsuya
no journal, ,
We are developing gamma-ray-induced positron annihilation spectroscopy at UVSOR-III. This method enables defect analysis of the entire bulk sample with a thickness of several cm, which was difficult to measure with the conventional method using a positron radiation source. Currently, the user use of the positron lifetime measurement method is being developed, and in parallel with this, the coincidence Doppler broadening method, the age-momentum correlation measurement method, and the spin-polarized positron spectroscopy are being developed. Here, we will describe the development status of them.
Goto, Aki*; Tagawa, Masahito*; Michishio, Koji*; Oka, Toshitaka; Yamashita, Shinichi*
no journal, ,
Films of polyethylene, polypropylene and polystyrene were irradiated with AO, and their surface morphologies and free volumes were investigated. Nanoscale protrusions were formed for all sample surfaces with the AO fluences of 
atoms/cm
- 
atoms/cm. The free volumes in the surfaces within 40 nm - 50 nm decreased due to the AO irradiations.
Nakagawa, Seiko*; Oka, Toshitaka; Fujii, Kentaro*; Yokoya, Akinari*
no journal, ,
Radicals produced in crystalline L-alanine-3,3,3-d3 and L-alanine-d4 were observed by the electron spin resonance (ESR) technique during 1.5 keV soft X-ray irradiation. The line width of the ESR spectra obtained by the soft X-ray irradiation was 1.5 times wider than that of hard X-rays. The efficiency of the radical yield by the soft X-ray irradiation was 10
relative to that by 
-irradiation. The product formed by the radical recombination was observed by an LC/MS analysis. For the soft X-ray irradiation, many radicals will be lost by the efficient radical-radical recombination due to the higher density of the radicals, just as the high-LET irradiation by heavy ions.