Radioactivity Concentrations in Soil Surrounding Experimental Power Reactor Development Plan in Serpong of Indonesia

The evaluation of environmental radioactivities measurements data surrounding RDE (Reaktor Daya
Eksperimental/Experimental Power Reactor) development plan in Serpong Nuclear Area (KNS) along year 2015 is
presented. Measurements of environmental radioactivities were carried out from radius 0 km to 50 km. The environmental radioactivities of 226Ra, 232Th, 228Th, 40K and 137Cs were measured from the samples of soils with the deepness of 0-5 cm and 5-20 cm. The sampling strategy is done by dividing the area into seven circular zones over 16 angular sectors with the purpose of knowing the distribution of radioactivities in the environmental surrounding KNS, particularly 137Cs,in conducted to the investigation of the releasing radioactivities from GAS reactor stack. The results show that the average concentration of natural radioactivities of 226Ra, 232Th, 228Th and 40K in the soil with the deepness of 0–5 cm is
21.272.39, 32.223.46, 30.593.15 and 72.8917.38Bqkg-1, respectively as well as the deepness of 5–20 cm is 22.88 2.61, 33.64 3.71, 30.593.10 and 68.32 7.35 Bqkg-1, respectively. In comparing to other investigations in different locations in the world, it was found that the concentrations of natural radioactivity were lower than those of world
average values except the 232Th.The average concentration of 137Cs in soil with the deepness 0–5 and 5–20 cm viewed
over the angular sector is in range of <MDC –1.430.21 and <MDC –0.420.08 Bqkg-1, respectively while viewed over radius from KNS is in range of 0.150.05–0.860.21 and <MDC –0.250.18 Bqkg-1, respectively. The concentrations of 137Cs in soils, either in the deepness of 0–5 or 5–20 cm, are independent to the radius from KNS indicating that the distributed 137Cs in soil is not from KNS. In other side, the highest average concentration of 137Cs is to the south east direction from KNS while the dominant wind direction in that area was to the west. It confirms that the distributions of 137Cs in the soil are not from KNS.