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Abstract
In Egypt, zirconium silicates are widely used in ceramic industries. This sector of industry imports about 42 k tons from these materials per year from different countries such as Italy, Spain, Germany. Holland and China. Zirconium silicate may contain significant levels of radioactivity. The processing of these materials can case significant increase in the exposure of workers and member of public above the natural radiation background.
The present work is aimed at assessing the occupational radiation exposure due to handling of raw materials and products in ceramic industry.
The radioactivity concentrations of 238U, 232Th and K in zirconium silicate as raw materials and glazed tile samples as products have been measured. The external dose equivalent and the internal dose due to dust and radon daughter inhalation inside some ceramic factories have been also measured. The annual effective dose for workers in these factories is calculated.
The average activity concentrations of 238U and 232Th in zirconium silicate samples were 1879, 324 Bq/kg respectively and for 40K were less than the detection limit. For glazed tile samples the average activity concentrations of 238U, 226Ra, 232Th and 4K were about 66, 60, 42 and 400 Bq/kg respectively.
The external dose equivalent, in average, is 0.49 mSv/a. The committed effective dose for dust inhalation, in average, is 0.3 mSv/a and for radon daughter inhalation is 0.33 mSv/a. The calculated annual effective dose, in average, is 1.18 mSv/a.
The hazard due to the handling of raw materials for accumulated dose is calculated, by WISE Uranium Project Calculators, and the results of the excess lifetime cancer risk was 0.0944% or (1:1059) through 20 years work.
For the glazed tiles, as product materials, the annual effective dose and the hazard indexes due to the handling of these materials are dosculated. The annual effective dose, in average, is d7mSv/a. The fesults of radium equivalent Raq founded in average 153.98 Bq/kg twhich is lower than the recommended maximum value of 370 Bq/kg for safe handling use. The external and internal hazard index (H Home) were calculated and founded less than unity which means that according to the OECD criterion; this type of ceramics is acceptable for use as a construction or building material.
According to the data obtained, we can concluded that:
the natural radioactivity contained zirconium silicate as raw materials and glazed tiles as products show remarkable radioactivity levels, the annual effective dose for worker at the investigated ceramic factories is equal to 1.18 mSv/a which is higher than the value recommended by IAEA for public (1 mSv/a) and less than that recommended for occupations (20 mSv/a),
the occupational effective doses have been differentiated according to the different tasks and contact time occurs.
from this study, we recommended that: In the case of potential exposure to raw materials (zircon silicates); additional measurements should be considered at the areas where the recommended total effective dose for occupational workers could be exceeded were their exposure time schedules to be increased significantly, the use of local ventilation systems,
* reducing time to be spent in storage and grinding areas.
* finally the urgent need to impose the radiation regulations and standard to keep the occupational exposure glazed tiles As Low As Reasonable Achievable (ALARA).