Effect of cover layer on radiological impact of landfill for TENORM waste from tin industry in Bangka Island

Abstract

Tin slag waste from the smelter facilities on Bangka Island contains TENORM and can pose radiation risks to workers and the environment. Thus, a landfill facility is needed to minimize the radiological impact of TENORM waste. One of the important components of the landfill facility is the cover layer part that retards the migration of radionuclides to the biosphere and the infiltration of rainwater. As time passes, its performance will decrease due to the degradation of the geomembrane part thereby clay layer becomes a crucial part of long-term safety of the facility. Thus this study aims to obtain an optimum thickness of clay layer by evaluating the radiological consequences (dose and cancer risk) and analyzing the critical pathways using RESRAD-ONSITE 7.2 software. A receptor is a person who works above the landfill facility after its closure. Climatological data, activity concentration of radionuclides, landfill design, and hydrological data are used as the input parameters on RESRAD. The exposure pathways considered include external gamma, inhalation, soil ingestion, and radon inhalation. From the simulation, the maximum total dose and cancer risk reached the minimum value by applying 6 meters layer of clay, with the value of 0.92 mSv/y and 2.14 ×10−3, respectively. The critical pathway is the inhalation of radon. Therefore, 6 meters of clay layer is proposed to ensure safety until thousands of years after closure.