title: Establishing a NORM based radiation calibration facility.
abstract: An environmental radiation calibration facility has been constructed by the Radiation and Nuclear Sciences unit of Queensland Health at the Forensic and Scientific Services Coopers Plains campus in Brisbane. This facility consists of five low density concrete pads, spiked with a NORM source, to simulate soil and effectively provide a number of semi-infinite uniformly distributed sources for improved energy response calibrations of radiation equipment used in NORM measurements. The pads have been sealed with an environmental epoxy compound to restrict radon loss and so enhance the quality of secular equilibrium achieved. Monte Carlo models (MCNP),used to establish suitable design parameters and identify appropriate geometric correction factors linking the air kerma measured above these calibration pads to that predicted for an infinite plane using adjusted ICRU53 data, are discussed. Use of these correction factors as well as adjustments for cosmic radiation and the impact of surrounding low levels of NORM in the soil, allows for good agreement between the radiation fields predicted and measured above the pads at both 0.15 m and 1 m.
authors.affiliation: Radiation & Nuclear Science Unit, Queensland Health, Australia. Electronic address: johnD_wallace@health.qld.gov.au.
authors.forename: J
authors.initials: J
authors.lastname: Wallace
mesh_terms: D002138:Calibration; D004867:Equipment Design; D008962:Models, Theoretical; D009010:Monte Carlo Method; D011793:Queensland; D011834:Radiation Monitoring / Q000295:instrumentation*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*
chemical_list: D012990:Soil Pollutants, Radioactive
keywords: Air Kerma; Calibration; Low density concrete; Monte Carlo; NORM; Semi-infinite sources