Determination of the 14C activity level in the biota of the surroundings of NPPs

The results of 14C monitoring in the biota surrounding Czech NPPs (Temelin and Dukovany) are evaluated. The observed levels are compared with those in reference areas. Two types of area with different Suess effect load were selected as reference areas: clear sites ('A'), and sites where a medium local Suess effect is expected ('B'). The local Suess effect in the NPP areas is assumed to lie in between the 2 types of reference area. Statistical evaluation gave evidence of a significantly larger 14C activity in the biota surrounding the two NPPs in comparison with reference area B. The difference of 14C activity between the biota around Temelin and the biota in reference area A was found to be statistically significant and the interval of 14C activity increment could be determined. For Dukovany, only the upper limit of this interval (i.e., in comparison with reference area B) was demonstrable. The results of two linear samplings performed in the vicinity of Dukovany and Paks (Hungary) in 2006 are also outlined and discussed briefly.. The low 14C activity surplus in biota around those NPPs with PWR reactors is due to the low 14CO2 content of the gaseous effluents as compared to other reactor types. Other chemical species with 14C (with prevailing 14CH4) do not contribute to radiocarbon intake by photosynthesis in the surrounding biota. (orig.)