CHARACTERIZATION OF RADIOACTIVE PETROLEUM PIPING SCALE WITH AN EVALUATION OF SUBSEQUENT LAND CONTAMINATION

Scale formation in oilfield piping and equipment has been a problem for petroleum companies. In the past, scale waste from cleaning of piping and equipment has been considered nonhazardous. Naturally occurring radioactive material in the form of Ra-226 and, to a lesser degree, Ra-228 with their associated decay products have recently been discovered in the scale. Due to the lower abundance and short half-life, Ra-228 is not addressed in this paper. Ra-226, an alpha emitter, is a potential internal hazard to workers from the inhalation and ingestion of the dust produced during descaling or pipe cleaning operations. Along with this, a higher-than-normal background gamma exposure rate is seen where the pipe cleaning was routinely done. An evaluation of the radiation hazards associated with a retired pipe cleaning field was performed. Gamma exposure rates, Ra-226 concentration, and Ra-226 leachability were examined using scale containing soil from the field. Radon emanation from the soil was also determined.