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In this work the development results of the TRI-TIUM project is presented. The main objective of the project is the construction of a near real-time monitor for low activity tritium in water, aimed at in-situ surveillance and radiological protection of river water in the vicinity of nuclear power plants. The European Council Directive 2013/51/Euratom requires that the maximum level of tritium in water for human consumption to be lower than 100 Bq/L. Tritium levels in the cooling water of nuclear power plants in normal operation are much higher than the levels caused by the natural and cosmogenic components, and may easily surmount the limit required by the Directive. The current liquid-scintillation measuring systems in environmental radioactivity laboratories are sensitive to such low levels, but they are not suitable for real-time monitoring. Moreover, there is no currently available device with enough sensitivity and monitoring capabilities that could be used for surveillance of the cooling water of nuclear power plants. A detector system based on scintillation fibers read out by photomultiplier tubes (PMTs) or silicon photomultiplier (SiPM) arrays is under development for in-water tritium measurement. This detector will be installed in the vicinity of Almaraz nuclear power plant (Spain) in Spring 2019. An overview of the project development and the results of first prototypes are presented.

Different types of iron-or aluminium-based coagulants were used to study the influence of the key water potabilization processes of coagulation, flocculation, and decantation on the elimination of significant concentrations of uranium and radium. We first determined the physico-chemical and radiological characteristics of a natural water to use in the trials, to which we then added known activities of 233 U and 226 Ra. While the efficiency of the decontamination processes was found to be independent of coagulant dose, there was a clear dependence on the pH at which the coagulation was carried out, with the optimum for the elimination of uranium being pH 6 and for radium pH 10. Uranium elimination was independent of the type of coagulant used, but the best radium elimination was with the iron-based reagents.

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