engleski

Interlaboratory comparison and OBT measurements in biota in the environment of NPPK

Slovenia and Croatia share the Nuclear Power Plant Krško (NPPK), situated on the left bank of the Sava River. Tritium in all types of water samples has been regularly monitored for decades. On some sampling points it shows measurable and slightly elevated concentration in comparison with environmental background but fairly below 100 BqL-1. Tritium in organic tissues has not been part of regular monitoring program yet. It has attracted our attention when the new Hydroelectric Power Plant Brežice (HPPB) few kilometres downstream of NPPK became the project under construction. The dam of HPPB came into operation in 2017 when the water surface area in the vicinity of NPPK enlarged for factor of 10, the groundwater level and its hydrodynamics changed and might affect also the local climate. First preliminary samplings of organic material and measurements of organically bound tritium (OBT) before the construction of HPPB dam were performed in 2016 (Krištof et al., 2017) when tissue free water tritium (TFWT) and OBT were determined. The observed trends correlate with the predicted modelled trends of NPPK emissions. The values and their ratios are in accordance with the similar studies worldwide (Korolevych et al., 2014). Two tritium laboratories in Slovenia (JSI) and Croatia (RBI) decided to introduce the measurements of OBT into the inventory of their laboratory methods, check them in the international inter-laboratory inter-comparisons (Sironić et al., 2019) and harmonize both laboratories. Both laboratories proved their competence in determination of OBT. Harmonized and confirmed methods were applied on agricultural produce, growing in the vicinity of NPPK. Samplings were performed in spring and autumn when the produce was in different growing stages. Samples were collected on 17 sampling points, before and after the fully operational dam. Samples from each sampling point were split between both laboratories. Results of both laboratories are compared. The OBT values are not uniform for the whole sampling field and show similar correlation with the predominant wind direction. Rather similar behaviour is known from the regular monitoring program of C-14 which is performed on regular basis since 2006 (Krajcar Bronić et al., 2017). The paper will focus on the OBT values, their correlation with C-14 values and therefore with predominant wind direction. The presented results cover the time period before and after the HPPB dam became operational. The differences and similarities observed in agricultural produce will be presented and discussed.

organically bound tritium (OBT) ; Nuclear Power PLant Krško (NPPK) ; agricultural products ; interlaborator comparison

Rad također objavljen u Proceedings, ENVIRA 2019 5th International Conference on Environmental Radioactivity ENVIRA 2019: Variations of Environmental Radionuclides, 8 – 13 September 2019, Praha, Czech Republic ; page 165 ; ISBN 978-80-01-06692-8 (electronic version) 978-80-01-06691-1 (printed version) DOI https://doi.org/10.14311/ENVIRA.2019