Vol.24 - 1 Original
Effects of Helium Pre-Irradiation on Tritium Release from Thin Boron Film Deposited on Stainless Steel type 316
M. Matsuyama1), M. Tsukada1), K. Okuno2), Y. Oya3), A. Sagara4), N. Noda4), K. Watanabe1)
1) Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930-8555, Japan
2) Radiochemistry Research Laboratory, Faculty of Science, Shizuoka University, Ohya 836, Shizuoka
422-8529, Japan
3) Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
4) National Institute for Fusion Science, Oroshi-cho 322-6, Toki 509-5292, Japan
Abstract
The effects of helium pre-irradiation on trapping and release behavior of tritium
implanted into thin boron films deposited on a plate of stainless steel type S316 were examined by an
isothermal heating method and β-ray-induced spectrometry (BIXS). BIXS results showed that the helium
pre-irradiation caused an increase in the trapping amount of surface tritium. Isothermal heating of the
samples was carried out at temperatures in the range of 473 to 723K, and the decreasing rate of surface
tritium was measured by tracking changes in the intensity of X-rays induced by β-rays. It was found that
the decreasing rate of residual tritium obeyed first order reaction kinetics, indicating that the helium
pre-irradiation has no influence on the tritium release kinetics. Apparent activation energy of the
decreasing rate was determined to be 0.3 eV from temperature dependence of the decreasing rate constant,
which was about two-times larger than that measured without pre-irradiation of helium.