Page 707 - Radiation Safety
P. 707
CLASSIFICATION OF WORKING AREA
For NORM/TENORM production facilities, area classification are
summarized as below
External Surface Airborne
Radiation Contamination Contamination only
Source only only (assuming (assuming natural
Area Ra-226, natural thorium as the most
thorium and restrictive
progeny) radionuclide)
Clean Area < 0.5 µSv/h < 2 Bq/cm 2 < 0.003 Bq/m 3
Supervised Area 0.5 µSv/h – 3 µSv/h 2 – 7 Bq/cm 2 0.003 – 0.01 Bq/m 3
Controlled Area > 3 µSv/h > 7 Bq/cm 2 > 0.01 Bq/m 3
