Integral dosemeter as an indicator of external irradiation of organisms in water discharged from nuclear power plants

The results are discussed of experiments whose objective was to identify an indicator of external irradiation of organisms in water discharged from nuclear power plants and to measure doses in the water and in the sediments, or to assess external irradiation of organisms in conditions similar to natural conditions. The experiments proceeded in vats of 500 l each with water of a natural river composition and in tanks of 25 to 60 l in volume with water without sediments. CaSO4:Dy or Tm thermoluminescence detectors in lead filters of 0.3 mm or 0.5 mm in thickness and in a plastic cover, respectively, were found to be the most suitable dosemeters. The experimental results of dose measurement were compared to doses calculated from activities in water. The experiments also showed that for quick display of increased radionuclide contribution in water and/or for the determination of doses of external irradiation of moving water organisms it is appropriate to deploy detectors in water at a point remote from the sediment and in the sediment. (Z.M.). 3 tabs., 10 refs