A mass-spectroscopic study was made of diffusion in 3N5-purity material by monitoring the de-gassing rate of solid cylinders which were pre-loaded with H at about 600torr. At pressures of between 600 and 10-8torr, and 1100 and 2400K, the data obeyed:

D (cm2/s) = 4.1 x 10-3 exp[-9.0(kcal/g-atom)/RT]

Solution and Diffusion of Hydrogen in Tungsten. R.Frauenfelder: Journal of Vacuum Science and Technology, 1969, 6[3], 388-97