Radium 08 : R226, one of the natural isotopes that as a trace element may incorporate into the matrix of naturally forming barium or strontium sulfate scale and make it a very low level radioactive material (NORM scale)
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}