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Title:	Determination of long-term radiological hazard due to naturally occurring radioactive materials (NORM) in building materials in central area of Peninsular Malaysia
Authors:	Abdullahi Shittu (P87579)
Supervisor:	Aznan Fazli Ismail, Dr.
Keywords:	Radiation -- Dosage Radioactive pollution Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	15-May-2019
Description:	The building materials usually derived from soil and rock are known to contain naturally occurring radionuclides (NORM). Some of these materials may contain elevated concentrations of natural radionuclides and the use of them may result in the increase of radiation exposure to occupants. Any attempt to evaluate radiological hazard of building material can therefore be principally justified, especially considering that people spent 80% of their time indoors. For that reason, this study was carried out to determine the external and internal radiological risk attributed to building materials as well as to evaluate the potential factors influencing the indoor doses received by the occupant. A total of 102 samples of building materials were obtained from manufacturers or bought directly from local hardware stores in some region in Peninsular of Malaysia. The treated samples which have attained the secular equilibrium were analyzed using gamma spectrometry system for 12 hours. On the other hand, the Radon emanation coefficient (P) were determined up to 50 days at the interval of 2 days. The calculated activity concentrations and P were used as input parameter for RESRAD-BUILD computer code to evaluate long-term potential radiological hazards to the occupant. The results showed that the estimated P value and indoor 222Rn vary from 10.0 ± 0.4% to 30.0 ± 0.4% and 2.1 ± 0.1 to 53.6 ± 1.2 Bq m-3, respectively. The estimated P value of the building materials under investigation are in the order: cement brick > sand > Portland cement > red brick > gravel > tile. The external dose exposure, internal dose exposure and total effective dose equivalent (TEDE) in building were evaluated from 0 (initial year) up to 70 years. The simulation results were 92 ± 59, 689 ± 566 and 782 ± 569 μSv y-1 for indoor external, internal, and TEDE respectively. The variation of the indoor doses indicated a significant increase in the doses from 0 (initial year) to 30 years before became relatively constant up to 70 years. The results showed that the indoor doses received by the occupant were mostly contributed by walls of the building, contradictory to the common assumption that indoor doses are mostly originated from room floor or soil (foundation) beneath the building. Moreover, The calculated excess lifetime cancer risk (ELCR) due to indoor doses and TEDE were 4.8 ± 2.4 × 10-3 and 3.0 ± 2.3 × 10-3, respectively. The percentage of indoor radiation dose due to the walls based on the variation of wall thickness, room size, dweller position and ventilation were 51%, 60%, 56% and 56%, respectively. Meanwhile, the percentage indoor radiation dose due to room floor were 49%, 40%, 44% and 44%, espectively. In addition to that, the calculated external and internal radiological hazard indices found that all the values were below the recommended limit. The finding showed that the indoor doses were influenced by the wall thickness, room size, direction of measurement, dweller position and ventilation.Therefore, estimating indoor doses from the room floor and the foundation of the building are not sufficient to determine the total indoor doses received by the occupant. In general, the external and internal radiological hazard including long-term projection of indoor doses revealed that all the determined values were below the recommended limit (1500 μSv y-1). Hence, the study concluded that the radiological risk due to natural radionuclides in the studied building material were relatively low and does not pose significant radiological hazard to occupants.,Ph.D.
Pages:	234
Call Number:	QC475.S535 2019 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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