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Description
ABSTRACT
As part of Phase V of the decommissioning of the A1 NPP in Jaslovské Bohunice, remedial actions are planned in response to radioactive contamination of the Manivier discharge canal banks, if it will be shown as necessary. The Manivier open channel was used as a discharge pathway for authorized and emergency liquid discharges from the A1 and V1 NPPs.
Nowadays, the riverbanks are coved by grass, bushes and trees and therefore some of them are hardly accessible or not reachable at all. To ensure proper full scanning access of the monitored area, partial or complete clearing of the channel banks is necessary by means of grass mowing and / or woody vegetation removal. The vegetation may contain some radioactivity due to root transfer. Root transfer factor is usually low according to the IAEA literature (TRS No. 472), but it desirable to confirm the assumption.
At banks of Manivier, screening monitoring was performed using portable dose rate monitors to identify and localize areas with elevated dose rates up to level 1 µSv/h relative to typical background levels (0.10 µSv/h). At locations where the increased dose rate values from soil were detected, samples of soil, wood, and leaves were collected. The samples were processed and analysed in the laboratory by gamma spectrometry.
Results of initial survey in generally shown that content of radionuclides in the vegetation is relatively low from point of view of radiation protection and the removed vegetation can be disposed by a conventional manner. Dose rate survey, sampling procedures as well as the results of the initial monitoring survey and laboratory analyses of samples will be in more detail summarized in the article.