[en] The US Department of Energy (DOE) Office of Remedial Action and Waste Technology has as one of its goals the standardization of field measurements made by its remedial action contractors throughout the country. In support of this goal, the Technical Measurements Center (TMC) was established at the DOE Grand Junction Projects Office (GJPO) Facility, and was tasked with developing and/or recommending measurement methods for use in support of remedial action programs. One aspect of this technical support is the provision of calibration facilities for standardization of field measurements. The report presents the results of the design, construction, and characterization of 14 calibration pads enriched in radium-226. The 14 pads comprise 7 sets with a high and low activity pad in each set. The pads are concrete cylinders, approximately 5 feet in diameter by 2 feet in height. They are intended for use in calibrating portable field instruments that are used by remedial action contractors to make direct, in situ measurements of radium-226, thorium-232, and potassium-40. 23 refs., 6 figs., 14 tabs