Abstract. The accidental release of radioactive substances into the environment leads to the necessity of applying suitable countermeasures for the restoration of the polluted environment. However, despite their obvious benefits, such interventions may result in detrimental effects of economic, ecological and social nature that must be carefully evaluated.MOIRA-PLUS is a PC-based user-friendly, Computerised Decision Support System (CDSS) that helps decision makers to choose optimal countermeasure strategies for different kinds of aquatic ecosystems and contamination scenarios.CDSS MOIRA-PLUS is based on: a) Validated models to evaluate the behaviour of radionuclides in contaminated water bodies and biota and to assess the effect of countermeasures on the contamination levels; b) Models to assess the radiation dose to people and biota (fish) by the relevant exposure pathways, the effect of countermeasures, and the associated economic impact; c) Multi-Attribute value Analysis (MAA) module to assess the effectiveness of different management strategies by accounting for the social, the ecological and economic detriments and costs in relation to their benefits.The flexible structures of the environmental models implemented in MOIRA-PLUS allow the application of these models to several other types of pollutants, such as heavy metals. The CDSS can be applied to complex water systems comprised of lakes, reservoirs and rivers. The main principles underpinning the functioning of the CDSS MOIRA-PLUS will be described and discussed.

Abstract. In the mid-long-term after a nuclear accident, the contamination of drinking water sources, fish and other aquatic foodstuffs, irrigation supplies and people's exposure during recreational activities may create considerable public concern, even though dose assessment may in certain situations indicate lesser importance than for other sources, as clearly experienced in the aftermath of accidents like Chernobyl. The MOIRA system is designed to allow for a reliable assessment of the long-term evolution of the radiological situation and of possible alternative rehabilitation strategies, including an objective evaluation of their social, economic and ecological impacts in a rational and comprehensive manner. MOIRA also features a decision analysis methodology, making use of multi-attribute analysis, which can take into account the preferences and needs of different types of stakeholders. A decision-making exercise regarding such problems, in which MOIRA has been be used as a decision support tool, was organised in Spain involving the organizations responsible for emergency management and the affected services, as well as local and regional stakeholders and several international observers. The system resulted very helpful in assessing the overall situation and the alternative management strategies and also facilitated the interaction between agencies which reached a better common understanding of all related issues.

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MOIRA-PLUS is a decision support system (DSS) designed to address the mid and long-term issues after nuclear accidents causing the contamination of freshwater bodies and catchments with radionuclides. It is designed to allow for a reliable assessment of the long-term evolution of the radiological situation and of possible alternative rehabilitation strategies, including an objective evaluation of their social, economic and ecological impacts in a rational and comprehensive manner. MOIRA also features a decision analysis methodology, making use of multi-attribute analysis, which can take into account the preferences and needs of different types of stakeholders. The main functions and elements of the MOIRA-PLUS DSS are described summarily, together with the conclusions from end-user's experiences with the system. MOIRA-PLUS has proven to be a mature system, user friendly and relatively easy to set up. It can help to reassure the public by enabling a realistic evaluation of the complete impacts of possible recovery strategies. However, the users also identified possibilities for further improvement of the DSS.

Abstract. The LIANA Model Integration System is the shell application supporting model integration and user interface functionality required for the rapid construction and run-time support of the environmental decision support systems (EDSS). Internally it is constructed as the framework of C++ classes and functions covering most common tasks performed by the EDSS (such as managing of and alternative strategies, running of the chain of the models, supporting visualisation of the data with tables and graphs, keeping ranges and default values for input parameters etc.). EDSS is constructed by integration of LIANA system with the models or other applications such as GIS or MAA software. The basic requirements to the model or other application to be integrated is minimal -it should be a Windows or DOS .exe file and receive input and provide output as text files. For the user the EDSS is represented as the number of data sets describing scenario or giving results of evaluation of scenario via modelling. Internally data sets correspond to the I/O files of the models. During the integration the parameters included in each the data sets as well as specifications necessary to present the data set in GUI and export or import it to/from text file are provided with MIL LIANA language. Visual C++ version of LIANA has been developed in the frame of MOIRA project and is used as the basis for the MOIRA Software Framework -the shell and user interface component of the MOIRA Decision Support System. At present, the usage of LIANA for the creation of a new EDSS requires changes to be made in its C++ code. The possibility to use LIANA for the new EDSS construction without extending the source code is achieved by substituting MIL LIANA with the object-oriented LIANA language.