Radioactivity measurement of tungsten rods containing thorium

Radioactivity of tungsten rods containing 2 % thorium was measured by radioactivity measurement apparatus. Thorium contamination on the surface of rods was investigated and it was confirmed that tungsten rods Containing 2 % Thorium can be handled in the same manner with sealed source, by identifying quite low radioactivity. However, slight contamination was detected, after long time measurement by using a Ge (Li) semiconductor detector, in substances exfoliated from the surface of rods with the adhesive tape. (author)