NATURALLY OCCURRING RADIOACTIVE MATERIAL (NORM)
NORM encountered in oil and gas exploration, development and production operations originates in subsurface formations, which may contain radioactive materials such as uranium and thorium and their daughter products, radium 226 and radium 228. NORM can be brought to the surface in the formation water that is produced in conjunction with oil and gas. NORM in these produced waters typically consists of the radionuclides, radium 226 and 228. In addition, radon gas, a radium daughter, may be found in produced natural gas.
Because the levels are typically so low, NORM in produced waters and natural gas is not a problem unless it becomes concentrated in some manner. Through temperature and pressure changes that occur in the course of oil and gas production operations, radium 226 and 228 found in produced waters may co-precipitate with barium sulfate scale in well tubulars and surface equipment. Concentrations of radium 226 and 228 may also occur in sludge that accumulates in oilfield pits and tanks. These solids become sources of oil and gas NORM waste. In gas processing activities, NORM generally occurs as radon gas in the natural gas stream. Radon decays to Lead-210, then to Bismuth-210, Polonium-210, and finally to stable Lead-206. Radon decay elements occur as a film on the inner surface of inlet lines, treating units, pumps, and valves principally associated with propylene, ethane, and propane processing streams.
Workers employed in the area of cutting and reaming oilfield pipe, removing solids from tanks and pits, and refurbishing gas processing equipment may be exposed to particles containing levels of alpha-emitting radionuclides that could pose health risks if inhaled or ingested.
Several states, including Texas, have enacted regulations regarding NORM identification and worker protection. While regulations vary from state to state, the general premise is to identify equipment that is contaminated with NORM, identify it in some cases or report it to the state in others, provide for the protection of workers and limit movement of the equipment.
Equipped with specialized detection meters, ESR personnel can help its clients identify and label equipment containing NORM, develop worker protection plans and provide notification to the state when required.