Experimental and simulation methods to evaluate the alpha self-absorption factors for radioactive aerosol fiber filters

Abstract

Air sampling for particulate radioactive material involves collecting airborne particles on a filter in order to measure the radioactivity in the environment or in working areas. The amount of alpha radioactivity collected on the sampling filter is frequently determined by global alpha-particles measurements. Several factors can affect the alpha energy while passing through the filter to reach the detector. The most affecting factor on the alpha spectrum degradation is the absorption of alpha particle energies in the filter fibers. The fibers' density can range from 1 to 9 mg cm-2. The counting losses can accordingly be important, and the global activity in the filter can be underestimated. The complexity of the experiments and the diversity of the filter types, filtration conditions as well as detector types used for survey incite us to formulate a numerical model to simulate the correction factors of the degraded activity. Comparisons between experimental and simulated correction factors for a commonly used filter are presented. The good agreement found between experimental and calculated values validates the method in the studied conditions. © 2009 Elsevier Ltd. All rights reserved