Thorium-232-Another TENORM Emerging as a Major Concern to Oil and Gas Industry

Few things make a community take notice more than the word “radioactive.” The oil and gas industry is familiar with technologically enhanced naturally occurring radioactive materials (TENORM), which have been known for decades.

By Donald Carpenter, Arcadis Senior Vice President and Chief Geochemist 

Few things make a community take notice more than the word “radioactive.” The oil and gas industry is familiar with technologically enhanced naturally occurring radioactive materials (TENORM), which have been known for decades. Thorium-232, a recently identified radionuclide considered to be another TENORM, is now considered an emerging contaminant as it is increasingly found in fracking-related operations. As more Thorium-232 instances arise with operations and maintenance related activities, the more risk oil and gas companies have with their social license to operate. Unintended and unexpected exposures have led to alarms at operational sites during maintenance and local landfills during disposal, causing shutdowns, external security responses and even litigation. It is the unintended and unexpected exposures that present the true problem. In order to minimize community alarm, the Thorium-232 contaminant must be identified and disposed of proactively. And now, we can do that, safely and cost-effectively. 

What is the Issue? 

TENORM that is present as radium-enriched barium (and other alkaline earth element) sulfate scale and Lead-210-dominated scale are commonly associated with oil and gas production and processing. These forms of TENORM form under established and predictable conditions during either handling of produced fluid brines or onward handling and processing of natural gas. Recent radiological sampling of shale-related fracking scales and sludge have found, quite unexpectedly, the presence of elevated activities of Thorium-232 (shown in the following table). 
The presence of this recently identified radionuclide has raised interest by state regulators as to potential threats and the acceptability of disposal of Thorium-232 scales and sludges in municipal landfills. Further, due to the elevated activities of Thorium-232, a federal statute pertaining to the prohibition of “source material,” may cause this form of TENORM to be regulated at the federal level, unlike the other forms of TENORM. 

Predictably Identifying TENORM to Prevent Alarm 

Upon identification of this new radionuclide associated with oil and gas production, Arcadis’ geochemists undertook an analysis as to its possible mobilization within produced fluid brines and processes leading to its potentially adverse concentration in scales and sludges. This analysis showed that, similar to naturally occurring radium, the high dissolved salt content within produced fluid brines, especially those formed within deep and “hot” production horizons increases the solubility of thorium to comparatively low, but nonetheless non-trivial concentrations. These brines then can transport dissolved phase thorium to the surface where upon cooling the precipitation of amorphous silica concentrates the thorium into a potentially actionable scale or sludge consistent with the measured activities reported in the above table. The presence of this form of TENORM can be especially problematic when found unexpectedly causing serious and costly project delays. Alternatively, when predictively identified through specialty geochemical modeling and focused investigations, these problems can be largely eliminated allowing for an “as-planned” project. These preliminary efforts can be completed expeditiously and cost effectively. While this form of TENORM is raising alarm today, we see a true opportunity to make the handling of Thorium-232 no more disconcerting than the disposal of lead-based paint – something that not too long ago was also a major concern. 

 For queries you may have related to this emerging TENORM issue or to discuss what optimal remedies may be applied to the same, please contact: 

 Donald Carpenter, Senior VP / Chief Geochemist 

+1 810 224 2159 


 Keith Dias, Client Director +

1 713 953 4860

Donald Carpenter

Environment Ask me a question