C studies in the vicinity of the Czech NPPs

The Czech Republic has two nuclear power plants (NPPs) equipped with light water pressurized reactors (LWPR). Annual sampling of biota for [sup.14]C activity monitoring by Nuclear Physics Institute in cooperation with the National Institute of Radiation Protection started in 2002. We present the results of biota monitoring covering two sampling periods 2002-2005 and 2007-2008. The considerable problem in the case of biota sampling for monitoring purpose is given by a relatively short period of biota accumulation for prevailing types of biota samples (leaves of deciduous trees or agricultural plants), which usually lasts from several weeks to 2 months. The short period of sample accumulation can also be partly overlapped by a service period of reactor outage in a given NPP. On the base of our several years' experiences we have changed a type of the sampled material to reduce variations of observed activities and to precise reference levels in the exposed and reference sites. Keywords Radiocarbon in biota * Nuclear power plants * [sup.14]C monitoring * Sampling material selection