engleski

Influence of Refuelling of the Krško nuclear Power Plant on Environmental 14C levels

Monitoring 14C activity in the atmospheric CO2 and in biological samples (apples, corn, wheat, grass) in the close vicinity of the Krško Nuclear Power Plant (NPP) was performed regularly since 2006 to estimate the possible influence of the plant on environmental 14C levels and the possible contribution to the effective dose of local population through food chain. Atmospheric CO2 on two locations was collected regularly every two months. Biological samples were collected twice a year (in June/July and September/October) on several locations very close to the plant, in a radius of about 1 km from NPP, and on the control point at Dobova, 12 km from the plant. Increase of 14C activity in atmospheric CO2 was observed during and immediately after the refuelling of the power plant, performed every 18 months. It is more pronounced on the location in the SW-NE direction that coincided with the most pronounced wind directions. 14C activities in biological samples collected close to the Krško NPP are higher than the activities on the control point, and depend both on the distance from the plant ventilation exhaust system and on wind direction. Significantly higher activities were measured in biological samples collected after the spring refuelling (2006 and 2009). They can be explained by the influence of plant effluents on the photosynthesis process, while autumn effluents (2007 and 2010) do not significantly influence the 14C activity in biological samples. The increase of total annual effective dose to local population through ingestion in the years of spring refuelling was estimated to 0.015 %. However, this increase in the effective dose is much lower than the total uncertainty of the estimate, obtained by combined variations in 14C activity in biological samples, measurement uncertainties and uncertainties in the ingestion model, and thus it may be neglected.

14C monitoring ; atmospheric CO2 ; plants ; NEK

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