الفهرس 
COVEROnly 14 pages are availabe for public view
 |  | from | 286 |  |  |
| | | from | 286 | | |
Abstract
Naturally occurring radionuclides are present in many natural resources. Elevated concentrations of these radionuclides are often found in certain geological materials, namely igneous rocks and ores. Human activities that exploit these resources may lead to enhanced concentrations of radionuclides (often referred to as technologically enhanced naturally occurring radioactive material (TE-NORM). Enhanced levels of natural background radiation are encountered in many occupational industrial activities involving a large number of workers. Uncontrolled activities associated with TE-NORM can contaminate the environment and pose a risk to human health. This risk can be alleviated by the adoption of controls to identify where NORM is present; and cleaning the NORM-contaminated equipment and waste management while protecting workers. The main objective of this study is to investigate the natural radioactivity and the hazard parameters in the TE-NORM samples from different industrial activities. Also to describe the models and develop the computer codes that allow one to estimate the risk of cancer resulting from any specified dose of ionizing radiation for occupationally workers in different industrial activities. The present study deals with 50 different samples. This waste generated from petroleum fields, phosphate fertilizers samples, consumer product samples from China, ceramic and zircon samples. The radon exhalation rates calculated using solid state nuclear track detector (CR-39). The value of radon exhalation rate 58.82±5.3 x103, 4.28±0.49 x103 and 0.306± 0.025 x103 Bq/m2 h for scale, sludge and sand, respectively. The value of radon exhalation rate 82.67±7.98, 62.58 ± 5.7, 46.16 ± 3.91 and 198.51±18.68 Bq/m2 h for phosphate fertilizers samples, consumer product samples from China, ceramic and zircon samples, respectively. The 226Ra activity concentrations were 301.4±771.5, 52.1±438 and 2.56±55.37 kBq/kg for scale, sludge and sand, respectively. The 226Ra activity concentrations were 758.77±23.3, 744.47±57.4, 417.1±25.4 and 18317.4±26.9 Bq/kg for phosphate fertilizers samples, consumer product samples from China, ceramic and zircon samples, respectively.
The average activity concentrations of 238U, 232Th and 40K for TE-NORM samples are higher than the world wide average value. The worldwide average values (32, 35, 45 and 420) for 226R, 238U series, 232Th series and 40K, respectively.
The estimated hazard parameters in all TE-NORM samples are higher than the recommended values. The estimated average annual effective dose for both scale and sludge petroleum samples is higher than the recommended limits for occupationally worker while for the rest TE-NORM samples under investigation it is lower than the recommended values for workers.
The excess relative risk and excess absolute risk of cancer are computed by special computer codes which developed for this study and tested. The obtained results proved that the workers with TENORM, in particular of oil activities, are under inevitable threat of cancer. They should be classified as occupationally radiation workers. In this study the general principles of radiation protection are primarily implemented by means of good protective measures at the workplaces. Hence, exposure control and adequate dosimetry assessment are the most critical components of a health and safety program.