RADIOCARBON IN THE ATMOSPHERE OF THE ZLKOVCE MONITORING STATION OF THE BOHUNICE NPP: 25 YEARS OF CONTINUOUS MONTHLY MEASUREMENTS

Radiocarbon variations in the atmosphere have been observed at the Zlkovce monitoring station of the Bohunice nuclear power plant (NPP), situated only 5 km ESE from the NPP. The observed C-14 levels provide unique evidence of a decreasing long-term impact of the Bohunice NPP on the region. Simultaneously, decreasing emissions of fossil fuel carbon dioxide in the atmosphere of the monitoring site have been found. The observed Delta C-14 variations with time have attenuating amplitudes and decreasing mean values, showing maxima in summer and minima in winter, the latter primarily caused by increased emission of fossil CO2 in winter months. Sporadic short-term releases of C-14 from the Bohunice NPP were observed at the Zlkovce station. The annual atmospheric Delta C-14 variations compared with tree-ring data collected at the Zlkovce village show reasonable agreement. The observed Delta C-14 levels after 2005 are close to the European clean-air levels as measured at the Jungfraujoch (3450 m asl) monitoring station.