[en] The decision support system for offsite nuclear emergency management RODOS (Real-time on-line decision support), developed under several EC RTD Framework Programs, contains many models related to support decision making in case of a nuclear or radiological emergency. Based on the request of the end users, it was re-engineered based on the JAVA technology and further named JRODOS. The consequences of the Fukushima Daiichi Nuclear Power Plant accident clearly demonstrated the importance of modeling tools predicting the radionuclide transport in marine and freshwater environment and assessing the doses to the public via the aquatic food chain to improve decision making in general. As a consequence, such an activity was launched as part of the European project PREPARE aiming to integrate the 3-dimensional model THREETOX for the radionuclide transport in coastal waters, estuaries, deep lakes, and reservoirs into hydrological model chain of JRODOS - JHDM (JRODOS Hydrological Dispersion Module). So far JHDM contains several aquatic radionuclide transport models describing the sequence of the processes 'atmospheric fallout to watershed' - 'radionuclide inflow to a river net' - 'radionuclide transport in river' - 'doses via aquatic pathways'. The implementation of the THREETOX model into this chain by developing also a user friendly interface will extend the applicability of JRODOS to deep fresh water bodies and marine coastal waters. This paper describes the assessment capabilities of this advanced model chain for two examples of the JRODOS implementation in Ukraine. JRODOS is installed in the emergency centers for two Ukrainian Nuclear Power Plants (NPP) - Zaporizzhya NPP (ZNPP) and Rivne NPP (RNPP). The different models of the JHDM were customized for these NPPs taking into account the characteristics of the water bodies in the surroundings of the NPPs. For the RNPP, located at the bank of the Sozh River which is a tributary of the Pripyat River, the modeling chain includes 'atmospheric fallout to watershed' - 'radionuclide inflow to river net using the RETRACE -R model' - 'radionuclide transport in river using the 1D model RIVTOX' - 'doses via aquatic pathways using the FDMA model', For the ZNPP, located close to the large (18 cub.km) Kakhovka Reservoir, the modeling chain consists of 'atmospheric fallout to reservoirs water surface' - 'radionuclide transport in the reservoir applying the 3D model THREETOX' - ' radionuclide transport in the Dnieper river downstream of the Kakhovka Reservoir applying the 1D model RIVTOX'- 'doses via aquatic pathways applying the FDMA model'. The above mentioned model chains have been tested for different accidental release scenarios for both NPPs. These dose assessments for potential major release accidents are extremely important to improve emergency preparedness and planning. Document available in abstract form only. (authors)