Sains Malaysiana 39(4)(2010): 607–613

Penilaian Risiko Radiologi Bahan Binaan Konkrit di Semenanjung Malaysia

(Radiological Risk Assessment of Concrete Building Materials in Peninsular Malaysia)

Aznan Fazli Ismail*, Amran Ab. Majid, Muhamad Samudi Yasir

Redzuwan Yahaya & Ismail Bahari

Pusat Pengajian Fizik Gunaan, Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Diserahkan: 25 Ogos 2009 / Diterima: 17 November 2009

ABSTRAK

Penggunaan bahan binaan yang mengandungi bahan radioaktif tabii (NORM) yang tinggi boleh meningkatkan kadar dos dedahan kepada penghuni di dalam sesebuah bangunan. Kebimbangan terhadap impak radiologi kepada penghuni menyebabkan perlunya dilakukan penilaian hazard radiologi yang berpunca daripada bahan binaan. Sehubungan itu, objektif kajian ini adalah untuk menentukan aras keradioaktifan tabii dalam bahan binaan di Malaysia serta menilai risiko radiologi yang diterima oleh penghuninya. Sebanyak 46 sampel pasir, 43 sampel kerikil dan 13 sampel simen Portland telah dianalisis menggunakan sistem spektrometri sinar gama. Hasil kajian mendapati kepekatan aktiviti bagi ketiga-tiga sampel bahan binaan berada pada julat 4.4 Bq kg^-1 hingga 354.9 Bq kg^-1, 2.4 Bq kg^-1 hingga 263.9 Bq kg^-1 dan 15.1 Bq kg^-1 hingga 1931.7 Bq kg^-1 bagi masing-masing 226Ra, 232Th dan 40K. Pengiraan kadar dos dedahan dalam bangunan mendapati semua sampel menghasilkan dos di bawah nilai 1500 μSv tahun-1, iaitu jumlah had dos yang disyorkan bagi bahan binaan. Hasil analisis ke atas nilai indeks aras perwakilan sinar gama, indeks hazard luaran dan indeks hazard dalaman mendapati sebahagian sampel memberikan bacaan melebihi nilai satu, iaitu had yang ditetapkan bagi bahan binaan. Penilaian risiko radiologi kepada penghuni dengan menggunakan kod komputer Resrad-Build mendapati kadar dos dedahan yang berpunca daripada simen Portland, pasir dan batu kerikil meningkat pada setiap tahun sepanjang tempoh 50 tahun.

Kata kunci: Bahan binaan; bahan radioaktif tabii; risiko radiologi; Resrad-Build

ABSTRACT

The use of building materials containing high concentration of naturally occurring radioactive material (NORM) may result in the increase of radiation dose rate inside the building. The assessment of radiological hazard in building materials is necessary due to the concern of radiological impact to its dwellers. Thus, the objectives of this study were to determine the level of natural radioactivity in Malaysia’s building materials and to assess the associated radiological risk among dwellers. A total of 46 sands, 43 gravels and 13 Portland cement samples have been analysed using a gamma spectrometry system. Activity concentrations of 226Ra, 232Th and 40K were found to be in the range of 4.4 Bq kg^-1 to 354.9 Bq kg^-1, 2.4 Bq kg^-1 to 263.9 Bq kg^-1 and 15.1 Bq kg^-1 to 1931.7 Bq kg^-1, respectively. The indoor dose rates were found to be lower than 1500 μSv year^-1, which is the recommended limit for building materials. A few samples were found to have high values of the representative gamma level index, external hazard index and internal hazard index compared to the suggested value of one. The radiological risk assessments to dwellers using Resrad-Build computer code showed that the dose rates for the Portland cement, sand and gravel increased annually over a period of 50 years.

Keywords: Building materials; natural radioactivity; radiological risk; Resrad-Build

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*Pengarang untuk surat-menyurat; email: aznan_sn@yahoo.com