Construction of a Zircon-Cement Pad and Calibration of Portable Survey Meters for Environmental Radiation Measurements


Zircon sand, a by-product of tin mining was collected from N’gell valley Tin Mining Company at 42km along Barikin Ladi road in Plateau State. The sand was characterized for activity content using NaI(Tl) scintillation detector. The activity of thorium in the zircon sand was 9726.151±20.16Bq/kg, while that of radium-was 538.848±10.08Bq/kg. The activity of cement was found to be very minimal with radium being 23.124±1.636Bq/kg, potassium 4.648±1.446Bq/kg and thorium 34.845±1.655Bq/kg. A ratio of two parts zircon sand to one part cement was thoroughly mixed with water to construct the calibration slab. Measurement of the activity over the slab from equidistant positions from the center shows that activity was uniformly distributed. The theoretical dose-rates at different heights from the center were calculated and were used to derive the calibration factor for different detectors available. The calibration factors for the three detectors are LUDLUM NaI(Tl) survey meter 0.509, X-ray and Gamma radiation ATK1120 0.233 and RDS-120 survey meter .39. The slab can be used as a calibration pad for calibrating survey meters for environmental radiation level measurements.