Sains Malaysiana 52(1)(2023):
271-280
http://doi.org/10.17576/jsm-2023-5201-22
Penentuan Kepekatan Keradioaktifan Radionuklid Semula Jadi dan Indeks Bahaya Sinaran pada Musim Hujan dari Tanah di Kawasan Sekitar Kemudahan Simpanan Jangka Panjang (LTSF) Bukit Kledang,
Perak
(Determination of Natural
Radionuclide Radioactivity Concentration and Radiation Hazard Index during the
Rainy Season from the Soil in the Area Around the Long-Term Storage Facility (LTSF) Bukit Kledang, Perak)
MOHD IZWAN ABDUL ADZIZ1 & KHOO KOK SIONG1,2,*
1Jabatan Fizik Gunaan, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 UKM Bangi,
Selangor Darul Ehsan, Malaysia
2Pusat Penyelidikan Teknologi (NUKLEAR), Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 UKM Bangi,
Selangor Darul Ehsan, Malaysia
Recieved: 22 April 2022/Accepted: 30
September 2022
Abstrak
Kajian
dan pemantauan yang dilakukan terhadap taburan dan penentuan aktiviti keradioaktifan radionuklid semula jadi boleh dijadikan panduan dan rujukan serta amat berguna terutamanya ketika berlakunya dedahan sinaran yang tinggi dan tidak terancang daripada sumber antropogenik dan kemalangan nuklear global. Sampel tanah permukaan dari 12 lokasi yang telah dikenal pasti di sekitar kawasan kemudahan repositori telah diambil untuk dijalankan kajian analisis penentuan kepekatan keradioaktifan dan indeks bahaya sinaran. Pengukuran kepekatan radioaktif dalam sampel tanah dilakukan dengan menggunakan sistem pembilangan spektrometer gama yang dilengkapi dengan pengesan High Purity
Germanium (HPGe). Keputusan yang diperoleh menunjukkan kepekatan radioaktiviti 238U adalah berjulat antara 17.83 - 31.80 Bq kg-1, 234Th adalah berjulat antara 23.18 - 40.64 Bq kg-1, 226Ra adalah berjulat antara 20.09 - 32.80 Bq kg-1, 228Ra adalah berjulat antara 21.20 - 38.88 Bq kg-1 dan 40K adalah berjulat antara 9.11 - 51.39 Bq kg-1 dengan nilai purata masing-masing adalah 21.45 Bq kg-1,
28.17 Bq kg-1, 24.00 Bq kg-1, 27.43 Bq kg-1 dan 24.01 Bq kg-1. Nilai kepekatan radioaktiviti radionuklid tersebut didapati setara dengan nilai yang pernah dilaporkan dalam kajian terdahulu di Semenanjung Malaysia. Nilai purata yang diperoleh bagi keempat-empat parameter Indeks Bahaya Radiasi iaitu aktiviti bersamaan radium (Raeq), kadar dos luaran (D), dos berkesan tahunan dan indeks bahaya luaran (Hex) masing-masing adalah 66.37 Bq kg-1, 29.13 nGy j-1,
20.16 dan 0.18. Nilai yang diperoleh ini adalah rendah berbanding nilai purata dunia dan nilai piawaian yang diguna pakai secara global iaitu masing-masing adalah 370 Bq kg-1,
57nGy j-1, 480.00 μSv dan 1.0. Perbandingan dengan kajian sebelum ini juga mendapati nilai bagi keempat-empat parameter adalah rendah dan setara. Ini menunjukkan tahap bahaya radiasi di kawasan sekitar kajian adalah selamat untuk orang ramai.
Kata kunci: Bahan radioaktif semula jadi; kemudahan repositori; musim hujan; spektrometer gama; tanah
Abstract
Continuous research and monitoring
on the distribution and determination of these
natural radionuclides' activity as a guide and reference and are very useful,
especially in an accidental exposure. Surface soil samples from 12 locations
that have been identified around the repository facility area were taken for
the study. Radioactive concentrations in soil samples were measured using a
gamma spectrometer counting system equipped with an HPGe detector. The results obtained showed that the radioactivity concentration of 238U
ranged between 17.83 - 31.80 Bq kg-1, 234Th
ranged between 23.18 - 40.64 Bq kg-1, 226Ra
ranged between 20.09 - 32.80 Bq kg-1, 228Ra
ranged between 21.20 - 38.88 Bq kg-1 and 40K
ranged between 9.11-51.39 Bq kg-1 with
average values of 21.45 Bq kg-1,
28.17 Bq kg-1, 24.00 Bq kg-1, 27.43 Bq kg-1, and 24.01 Bq kg-1, respectively. The values obtained from
this study were low or equivalent to the values previously reported in previous
studies. It was also found that the mean/mean values obtained for the four
parameters of the Radiation Hazard Index, namely radium equivalent activity (Raeq), external dose rate (D), annual effective
dose and external hazard index (Hex) were 66.37 Bq kg-1, 29.13 nGy h-1, 20.16 μSv and 0.18, respectively. These obtained values are
low compared to the world average values and the values of globally applied
standards (370 Bq kg-1, 57nGy h-1, 480.00 μSv & 1.0, respectively). Comparison with previous studies also found
that the values for all four parameters were low and equivalent. This indicates
that the level of radiation hazard in the area around the study is safe for the
public.
Keywords: Gamma
spectrometer; natural radioactive material; soil; repository facility; wet
season
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*Corresponding author; email: khoo@ukm.edu.my
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