Sains Malaysiana 39(4)(2010): 599–605
Statistical Prediction of
Environmental Gamma Radiation Doses, in Perak, Malaysia
(Ramalan
Statistik Dos Sinar Gama Sekitaran, Perak, Malaysia)
Zalina Rahmat*, Ismail Bahari, Muhammad Samudi Yasir, Redzuwan Yahaya & Amran Ab. Majid
School of Applied Physics, Faculty of
Science and Technology
Universiti Kebangsaan Malaysia, 43600
Bangi, Selangor, Malaysia
Diserahkan: 30 April 2009 / Diterima:
29 Januari 2010
ABSTRACT
The
concentrations of Naturally Occurring Radioactive Material (NORM) and their corresponding terrestrial gamma radiation have been
shown to be associated with certain lithology and soil types. A possible
relationships among gamma radiation levels, and the lithology and soil types
make it possible to predict ionizing radiation level of an area that cannot be
directly measured. A study was carried out to statistically predict and
validate environmental gamma radiation dose rates based on actual field
measurements using a sodium iodide detector. Results obtained showed that the
predicted dose rate (Dp) may be
determined using a multiple correlation regression equation, Dp = 0.35DL + 0.82 Ds – 0.02, that integrates dose rates contributed by different
lithological structures (DL) and soil
types (Ds). Statistical analysis on 32
different lithology and soil type combinations showed that more than 50% of the
predicted data were not significantly different from the data measured in the
field. A predicted isodose map was subsequently plotted base on 4 dose rate
classes ranging from 0.1 – 0.3 μSv h-1.
Keywords: GIS; isodose map; Malaysia; NORM
ABSTRAK
Kepekatan
bahan radioaktif tabii (NORM) yang
terdapat dalam tanih dan aras gama terestrial berkaitan dipengaruhi oleh
litologi dan jenis tanih. Kemungkinan wujudnya perhubungan antara aras sinar
gama dan litologi serta jenis tanih ini memungkinkan ia digunakan untuk meramal
aras sinaran mengion sesuatu kawasan yang tidak boleh diukur aras sinarannya
secara langsung. Satu kajian telah dilakukan untuk meramal dan mengesahkan
secara statistik kadar dos sinar gama sekitaran berdasarkan bilangan pengukuran
sebenar di lapangan dengan menggunakan pengesan natrium iodid. Hasil kajian
mendapati bahawa kadar dos ramalan (Dp) boleh ditentukan melalui persamaan regresi korelasi berganda,
Dp = 0.35DL + 0.82 Ds – 0.02,
yang menyepadukan kadar dos sumbangan struktur litologi (DL) dan jenis tanih (Ds) yang berlainan. Analisis statistik terhadap 32 kombinasi
litologi dan jenis tanih yang berlainan mendapati lebih daripada 50% data
ramalan adalah tidak berbeza secara signifikan dengan data yang diukur di
lapangan. Sebuah peta isodos ramalan telah dibangunkan berdasarkan 4 kelas
kadar dos antara 0.1 – 0.3 μSv h-1.
Kata kunci: GIS; Malaysia; NORM; peta isodos
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*Pengarang untuk surat-menyurat; email: zalinarahmat@gmail.com
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