A Study on Radioactivity Levels in Sedimentary and Igneous Rocks Used as Building Materials in and Around Tiruchirappall
The paper presents the results of the study on the activity concentrations of primordial radionuclides (238 U, 232 Th and 40 K) in the rock samples collected from eight sedimentary rocks and six igneous rocks which supply stones for construction of buildi
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Research Centre, J. J. College of Engineering and Technology, Tiruchirappalli 620009, Tamil Nadu, India e-mail: [email protected] K. Jeevarenuka Dept of Civil Engineering, Shivani Engineering College, Tiruchirappalli 620009, Tamil Nadu, India
S. Sathiyamoorthy et al. (eds.), Emerging Trends in Science, Engineering and Technology, Lecture Notes in Mechanical Engineering, DOI: 10.1007/978-81-322-1007-8_44, © Springer India 2012
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1 Introduction Human beings are continuously exposed in their homes and places of work to ionise radiation and external gamma radiations [1]. The building materials derived from rocks and soil contain the natural radionuclides such as uranium (238U) and thorium (232Th) and their daughter products and singly occurring potassium (40K). The internal radiation exposure, affecting respiratory tract, is due to radon and radon decay products which emanate from building materials [2]. Knowledge of radioactivity present in building materials enables one to assess any possible radiological risk to human health [3]. In order to assess the possible radiological hazards to human health, it is important to study the radioactivity levels emitted by the building materials. The worldwide average specific activity of 238U, 232Th and 40K in the earth’s crust is estimated at 32, 45 and 412 Bq kg−1, respectively UNSCEAR [4]. The main objective of the present study is to identify and determine natural radionuclide activity in different rocks (Sedimentary and Igneous rocks) which are used as building materials in and around Tiruchirappalli district and to evaluate the specific activity concentrations, absorbed and annual effective dose rate to human. This study would also be useful for establishing a baseline data on primordial radionuclides present in different rock samples from various quarries located in Tiruchirappalli district.
2 Materials and Methods 2.1 Study Area Tiruchirappalli city is located in central part of Tamil Nadu, South India (10º 48′ N: Lat. 78º 42′ E: Long.) on the northern bank of river Cauvery. It is the fourth largest city in Tamil Nadu and spread in an area of 5,114 km2. The population density of the city is 3,601 persons per km2. Tiruchirappalli district is naturally endowed with rich building material resources such as sand, stones, granites, cements and bricks which are avidly utilised by several adjacent districts also and the granites and cement are exported to other countries as well. In general, rocks are classified into three types namely igneous, metamorphic and sedimentary based on their formation from earth curst. However, igneous and sedimentary rocks are commonly found in Tiruchirappalli district.
2.2 Sample Collections The rock samples were collected from 14 stone quarries spread over various locations of Tiruchirappalli district Fig. 1. About 2 kg of the rock sample was collected from each quarry. The solid matrix of the samples was powdered and sieved through 500 μm mesh. The samples were air-dried for several days to remove moist
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