Spatial and temporal evolution of the levels of tritium in the Tagus Riverin its passage through Caceres (Spain) and the Alentejo (Portugal)

This work is the result of a collaboration between Spanish and Portuguese l aboratories. The specific objective was to quantify the time evolution duri ng 1994, 1995 and 1996 of the radioecological impact of the liquid releases of H-3 from the Almaraz Nuclear Power Plant (ANPP) in the section of the T agus River corresponding to Caceres province in Spain and the Alentejo regi on in Portugal. We found that the temporal evolution of the levels of triti um depends on the management of the water held in the cooling reservoir of the ANPP and the presence of the dams that exist along the river. This mana gement regime has a 12-month period. Also the movement of the mass of triti ated water (HTO) downriver was much faster during 1996 than 1995 or 1994 du e to the hydrological differences between those years and consequently to t he different amounts of water transferred between the reservoirs of the dam s. From the hypothesis that hydrodynamically it is impossible to differenti ate tritiated water from non-tritiated water, a model was constructed that satisfactorily reproduces the temporal evolution of the 3H in the zone of t he Tagus River in which the exchange of water takes place, with the cooling reservoir of the Almaraz Nuclear Power Plant. (C) 2001 Elsevier Science Lt d. All rights reserved.