Release of tritium, protium, and helium from neutron-irradiated Li-Al alloy. II

Tritium gases (HT, T₂) and helium are released abruptly from highly neutron-irradiated Al-12.7 at.% ⁶Li alloy around 570 K on isochronal heating, and H² gradually above the same temperature. In the previous study of the neutron-irradiated Al-0.1 at.% ⁶Li alloy (J. Nucl. Mater. 139 (1986) 248), negligible release of helium at temperatures below the melting point of the alloy is attributed to trapping of helium at vacancies in the alloy. In this study, however, helium is released from the Al-12.7 at.% ⁶Li alloy at temperatures below the melting point of the alloy same as tritium. The origin of helium release is assumed to be the rupture of helium bubbles. Furthermore, radiometric method shows that most of tritium produced by Li(n, α)T reaction exists in the T^- state in the alloy. According to the above fact, an appropriate temperature to extract tritium from the alloy is suggested.