engleski

14C in biological samples and in the atmosphere in the vicinity of the Krško Nuclear Power Plant (Slovenia)

Monitoring of 14C in biological material and in the atmospheric CO2 in the close environment of Krško Nuclear Power Plant (NEK) in Slovenia has been performed since 2006. Sampling campaigns of biological samples (apples, corn, cereals, grass) from the sites in the immediate vicinity of the plant, as well as at a control site 10 km away, were performed twice a year. Carbon 14C activity was measured by direct absorption technique in LSC Quantulus 1220. Atmospheric CO2 was collected in bimonthly periods at two locations inside the NEK area by absorption of CO2 in saturated NaOH. The CO2 recovered from the carbonate was used for benzene synthesis, used for subsequent measurement in LSC. Most of the locations in the immediate vicinity of NEK showed slightly higher 14C activities in plants than the control site. Spatial distribution of 14C activities around NEK showed the dependence on the distance and on the direction. In all campaigns the highest activities were obtained at the locations that coincided with the most pronounced wind directions. At the control site the measured activities were more-or-less constant. Different biological materials taken at the same location gave the same 14C activity. 14C activity in atmospheric CO2 at the location inside the NEK area, which lies in the dominant wind direction, was always higher than at the other location, where no evident deviation from natural 14C activities was observed during regular operation of NEK. However, during the refueling outage periods and 2-3 months after it, higher 14C activities were detected at both sites. Based on the measurements, an assessment of the effective dose to the public could be obtained. The dose received by ingestion of food (fruits and vegetables) grown in the vicinity of the Krško Nuclear Power Plant resulted in the contribution to the total dose of most exposed individual of less than 1 μ Sv.

14C monitoring; nuclear power plant; biological material

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