External exposure due to gamma radiation emitted by NORM
Contaminated scales and sludges in pipes and vessels may produce significant dose rates.
Short lived progeny of Ra-226 (especially Bi-214) emit gamma radiation capable of penetrating the walls of components.
Some progeny of Th-228 (especially Tl-208) emit high energy gamma radiation having a relative large range.
Pb-210 emits only low energy gamma radiation which cannot penetrate the wall of components.
Dose rates measured outside surfaces of production equipment can be 1000 times greater than normal Background.
Opening the system for maintenance will increase dose rate.
TyTypical dose rate values observed in some oil production and proprocessing facilities:
Down hole tubing, safety valves (internal): up to 300 µSv/h
Wellheads: 0.1…22.5 µSv/h
Production lines: 0.3…4 µSv/h
Separator (scale, measured internally): up to 200 µSv/h
Separator (scale, measured externally): up to 15 µSv/h
Water outlets: 0.2…0.5 µSv/h