The concentrations of natural radionuclides in 6 different
colors of volcanic tuff stones which are derived from the Cappadocia
region in Turkey were determined using gamma-ray spectroscopy with
a HPGe detector, and the mineralogical composition and formula of
stones were determined by an X-ray powder diffractometer. The average
activity concentrations of 238U, 232Th and 40K
are 50.7, 58.6 and 717.6 Bq.kg–1, which are higher than
the world averages of 35, 30 and 400 Bq.kg–1, respectively.
The radium equivalent activities (Raeq), external hazard
index (Hex), and internal hazard (Hin) associated
with the natural radionuclides, alpha (Iα) and gamma
indices (Iγ) were calculated to assess the radiation
hazard of the natural radioactivity in the volcanic tuff stones.
The average indoor annual effective dose equivalent is 0.1 mSv.
All values of the indoor effective dose are lower than the exemption
dose value of 0.3 mSv. The calculated radium equivalent activity
values vary from 60.31 Bq.kg–1 to 281.32 Bq.kg–1 with
a mean of 189.78 Bq.kg–1. All values of radium equivalent
activity are lower than the world average. The average indoor absorbed
dose rate (Din) for volcanic tuff stones, calculated
to be 21.18 nGy.h–1, is lower than the world average
of 84 nGy.h–1.