Depth distribution of H-3, C-14 and Co-60 in decommissioning of the biological Shielding concrete of KRR-2

The depth distributions of the gamma emitting nuclides, H-3 and C-14 activities were characterized for the activated biological shielding concrete from a decommissioning of Korea Research Reactor-2(TRIGA Mark-II) by using a commercially available tube furnace and a liquid scintillation counter. The HTO vapor and 14CO2 gas generated from the tube furnace were trapped in HNO3 and Carbosorb bubbler, respectively. The H-3 and C-14 activities were measured by the liquid scintillation counter. The specific activities of H-3 and C-14 were calculated by considering the concrete mass and the recovery factor of the tube furnace. The detection limits for H-3 and C-14 were 0.048 and 0.028 Bq/g respectively. The specific activity of the H-3 and C-14 tends to decrease exponentially as the depth of the concrete becomes deeper from the surface. In addition, the H-3 and C-14 activities were in good agreement with the Co-60 activities analyzed for the biological shielding concrete of KRR-2. (authors)