Tritium adsorption on the materials for the turbomolecular pump with active magnetic bearing
J. Vac. Soc. Japan, 34 (1991) 158-161
Hitoshi Miyake, Kan Ashida, Masao Matsuyama, Kuniaki Watanabe, Mitsuru Sakurai
Abstract
To examine tritium contamination/decontamination characteristics of turbomolecular pumps,
which are regarded as potential candidates of vacuum and/or circulation pumps in large scale tritium handling systems,
we measured the ad/absorption of tritium on/in the component materials of a turbomolecular pump (TG600M, Osaka Vacuum).
It was observed that the amount of adsorption was in the order of
[MoS
2 coated metals] > [organic materials] > [metals], and that of absorption
was [organic materials] > [MoS
2 coated metals] > [metals]. The overall tritium inventory in this pump
was found to be at a rather low level, about 2.5 GBq, after being exposed
to the tritium gas amounting to about 2×10
5 Pa・sec.
The tritium ad/absorbed on/in the materials could be removed easily with vacuum heating above 200℃,
but below this temperature it was hard to remove most of ad/absorbed tritium.
From the view point of safety and environmental aspects, however, it is required to develop suitable
decontamination techniques and contamination free materials.