Car-borne Survey and Dose Assessment from External Radiation Exposure in Bangka Island

Abstract

Bangka Island with a history of more than 200 years of tin mining, has brought along the byproduct of heavy minerals which contain radionuclide elements. There are some concerns about this byproduct material contributing to natural radiation in the environment. In this study, a car-borne survey was conducted, to give an accurate assessment of natural background radiation in Bangka Island. The measurement of indoor and outdoor ambient dose rates in 146 houses was also conducted for the assessment of radiation dose from external exposure received by the public. The soil samples were collected and measured by a gamma spectroscopy system to find specific radionuclide contributions to external terrestrial exposure. From 3790 measurement points during the car-borne survey, the highest ambient dose equivalent rate was measured at 596 nSv h−1 found in Muntok area, while the mean value was 101 nSv h−1 and the median value was 95 nSv.h−1. The ambient dose equivalent rate distribution map shows a relatively higher value in the northern coastal area of the island, where the Pemali tin deposit was located. The annual effective doses received from external radiation in 146 houses of Bangka ranged from 0.44 mSv y−1 to 1.30 mSv y−1, with a median value of 0.66 mSv y−1. The soil contains a relatively higher amount of thorium (232Th) which contributes 75% to external radiation exposure in Bangka Island.