Characteristic of natural radionuclide in the rivers of palembang, pontianak and palangkaraya

River water is very beneficial for households and industries. River functions for households are include drinking, washing, bathing, transportation and tourism. River functions for the industry are electrical energy sources, irrigation, aquaculture, transportation of industrial products and others. Therefore, the characteristics of the Musi River in Palembang, the Kapuas River in Pontianak, and the Kahayan River in Palangkaraya, need to be researched, especially the natural radionuclide content. Water is taken 1 liter each with a plastic container at several sampling locations every 3 km along the river, especially water located near the industry. Samples were taken to the laboratory, allowed to stand for a month, put in Marinelli 1 Liter and measured by gamma spectrometry. The measured radionuclides were Pb-201, Th-230, Th-234, Ra-226, Th-232, Th-228, U-238, K-40 and Cs-137. Radionuclides found in the three river waters are Ra-226, Th-228 and K-40. The concentrations of Ra-226 radionuclide in Palembang, Pontianak and Palangkaraya are 0.06-3.09; 0.02-3.92; and 0.09-4.07 Bq/L respectively. Th-228 concentrations in Palembang, Pontianak and Palangkaraya are 0.03-0.60; 0.05-2.32; and 0.061.09 Bq/L respectively. K-40 concentrations in Palembang, Pontianak and Palangkaraya are 0.19-1.99; 0.19-58.41 and 0.69-1.95 Bq/L. The average concentration of natural radionuclides found in the three river waters is still below the limit value of environmental radioactivity, according to PERKA BAPETEN No. 7 of 2013 namely Ra-226 (1 Bq/L), Th-228 (0.35 Bq/L), Th-232 (0.73 Bq/L), Cs-137 (0.25 Bq/L) and K-40 (1.10 4 Bq/L).