NOSI-Ra: A Screening Framework to Inform Radiation Safety Survey Planning for Radium-Bearing NORM in Oil and Gas Production Systems

Radium-bearing naturally occurring radioactive material is a recurring radiation safety concern in oil and gas production. The radionuclides 226Ra and 228Ra may be mobilized in formation water, transported with produced water, and concentrated in scale, sludge, filters, tanks, separators, pigging residues, soils, and sediments. This paper proposes a semi-quantitative occurrence susceptibility index for radium-bearing scale and sludge to inform radiation safety survey planning. The framework combines five weighted components: radium mobilization potential, scale precipitation potential, produced-water burden, deposition and accumulation potential, and operational trigger potential. Empirical radiological evidence is treated separately through a noncompensatory trigger so that an elevated field indication or confirmed radium-bearing material cannot be diluted by low scores in other components. A data quality index reduces false confidence when information is incomplete. Four worked operational scenarios demonstrate how the core score, empirical trigger, and data quality alter survey sequence, portable instrument use, targeted sampling, high-purity germanium gamma-spectrometric confirmation, and work controls. The framework is a rule-based decision-support structure, not a validated predictive model, probability estimate, or substitute for direct measurement, regulatory requirements, or site-specific dose assessment. No field-validated improvement in efficiency or cost savings is claimed. Its present purpose is to make provisional survey planning transparent and testable until field calibration and validation are completed.