RADIOLOGICAL IMPACT OF USING DECORATIVE GRANITE AS AN ATTENUATOR OF IONIZING RADIATION.

Abstract

Granite is a widely available rock, which can be used as a shielding material, for bulk in the form of the aggregate in concrete. It has the weakness that it is more radioactive than many other rocks, which can be used in concrete. This paper looks at its properties as a shielding material and the activity level. Thus, the concentrations of 226Ra, 232Th and 40K, in granite were measured using a high pure germanium detector (HPGe). They were ranged from (15±4 to 49±5) Bq kg-1 for 226Ra, (22±4 to 78±4Bqkg-1) for 232Th and (791±13 to 1231±15Bqkg-1) for 40K. Radiological indices of radium equivalent concentration (Raeq), external (Hex), internal (Hin) and annual effective dose were less than worldwide recommended limits. The results emphasized, the granite samples had no radiation hazard. Nevertheless, the mass attenuation coefficients of granite samples were measured for the gamma rays of energy range 122-1408keV. The mass attenuation coefficients of the studied granite samples were ranged from 0.05 to 0.15cm2g-1. In addition, the average the half-value layer of granite was varied from 1.8cm for 122keV to 5.2cm for 1408keV. The results are that the attenuation characteristics are typical and match the values given by NIST for 'concrete' and that the activity levels of the samples examined are acceptable. Thus the granite may be used as an attenuator for ionizing radiation.