Assessment of the environmental contamination with long-lived radionuclides around an operating RBMK reactor station

The presence of man-made gamma emitting radionuclides in the region within 32 km radius of the Ignalina NPP/Lithuania has been investigated during the period 2001-2004, prior to the closure of the first of the two operating RBMK 1500-type reactors. Gamma spectrometric measurements of various terrestrial and aquatic plants as well as of soil samples showed moderate environmental contamination with the fission product 137Cs and with the neutron activation products 60Co and 54Mn. Traces of the activation products 65Zn and 110mAg were found in the nearest vicinity of the NPP. Activity concentrations were inhomogeneously distributed in the area of interest. Moss and algae samples showed the highest uptake of radionuclides. In addition to the gamma spectrometric measurements, the levels of 14C were determined in the same bio-indicator samples using accelerator mass spectrometry.