Radioactivity measurements in the aquatic environment using in-situ and laboratory gamma-ray spectrometry

The in-situ underwater gamma-ray spectrometry method is validated by inter-comparison with laboratory method. Deployments of the spectrometer KATERINA on a submarine spring and laboratory measurements of water samples with HPGe detector were performed. Efficiency calibrations, Monte Carlo simulations and the Minimum Detectable Activity (MDA) estimations were realized. MDAs varied from 0.19 to 10.4 (lab) and 0.05 to 0.35 (in-situ) Bq/L, while activity concentrations differed from 7% (for radon progenies) up to 10% (for 40K), between the two methods. - Highlights: • In-situ underwater gamma-ray spectrometry method is validated by the lab method. • MC simulations using MCNP5 reproduced experimental energy spectra and efficiency. • MDA of the in-situ method was an order of magnitude lower than the lab method. • The in-situ method was sensitive and cost-effective compared to the lab method