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