Seabed radioactivity based on in situ measurements and Monte Carlo simulations

• The KATERINA system was applied for marine sediments.
• MC simulations using MCNP5 reproduced experimental energy spectra and efficiency.
• The in-situ method provided quantitative measurements.
• The measurements were validated with lab-based methods.

Activity concentration measurements were carried out on the seabed, by implementing the underwater detection system KATERINA. The efficiency calibration was performed in the energy range 350–2600 keV, using in situ and laboratory measurements. The efficiency results were reproduced and extended in a broadened range of energies from 150 to 2600 keV, by Monte Carlo simulations, using the MCNP5 code. The concentrations of 40K, 214Bi and 208Tl were determined utilizing the present approach. The results were validated by laboratory measurements.