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 past accidents. In such circumstances there are a number of available countermeasure options, ranging from specific chemical treatment of lakes to bans on fish ingestion or on the use of water for crop irrigation. The potential actions can be broadly grouped into four main categories, chemical, biological, physical and social. In some cases a combination of actions may be the optimal strategy and a decision support system (DSS) like MOIRA-PLUS can be of great help to optimise a decision. A further option is of course not to take any remedial actions, although this may also have significant socio-economic repercussions which should be adequately evaluated. MOIRA-PLUS is designed to allow for a reliable assessment of the long-term evolution of the radiological situation and of feasible alternative rehabilitation strategies, including an objective evaluation of their social, economic and ecological impacts in a rational and comprehensive manner. MOIRA-PLUS 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 system are described summarily. Also the conclusions from end-user?s experiences with the system are discussed, including exercises involving the organizations responsible for emergency management and the affected services, as well as different local and regional stakeholders. MOIRAPLUS has proven to be a mature system, user friendly and relatively easy to set up. It can help to better decisionmaking by enabling a realistic evaluation of the complete impacts of possible recovery strategies. Also, the interaction with stakeholders has allowed identifying improvements of the system that have been recently implemented.

Assessment of the environmental and radiological consequences of a nuclear accident requires the management of a great deal of data and information as well as the use of predictive models. Computerised Decision Support Systems (CDSS) are essential tools for this kind of complex assessment and for assisting experts with a rational decision process. The present work focuses on the assessment of the main features of selected state-of-the-art CDSS for off-site management of freshwater ecosystems contaminated by radionuclides. This study involved both developers and end-users of the assessed CDSS and was based on practical customisation exercises, installation and application of the decision systems. Potential end-users can benefit from the availability of several ready-to-use CDSS that allow one to run different kinds of models aimed at predicting the behaviour of radionuclides in aquatic ecosystems, evaluating doses to humans, assessing the effectiveness of different kinds of environmental management interventions and ranking these interventions, accounting for their social, economic and environmental impacts. As a result of the present assessment, the importance of CDSS "integration" became apparent: in many circumstances, different CDSS can be used as complementary tools for the decision-making process. The results of this assessment can also be useful for the future development and improvement of the CDSS.

Entre las posibles secuelas de un accidente nuclear hay que contar con la contaminacion radiactiva a medio y largo plazo de los sistemas acuaticos de agua dulce. Frente a ese problema, es fundamental disponer de una evaluacion realista del impacto radiologico, ecologico, social y economico de las posibles estrategias de gestion, para poder adoptar las decisiones mas convenientes de forma racional. MOIRA es un sistema de ayuda a la decision desarrollado en el curso de los Programas Marco Europeos con participacion de la UPM, que ha sido mejorado y adaptado a los emplazamientos nucleares espanoles en los ultimos anos en el contexto del Proyecto ISIDRO, patrocinado por el Consejo de Seguridad Nuclear, con la participacion del CIEMAT y la UPM. El trabajo se centra en esos avances, principalmente relacionados con los sistemas hidraulicos complejos como los de los rios Tajo, Ebro y Jucar, en los que se ubican varias centrales nucleares espanolas.

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.

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.

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 an economic, ecological and social nature that must be carefully evaluated. MOIRA-PLUS is a PC-based user-friendly, computerised decision support system (DSS) that helps decision makers to choose optimal countermeasure strategies for different kinds of aquatic ecosystems and contamination scenarios.The DSS 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 contamination levels;(b) Models to assess the radiation dose to people and biota (fish) by relevant exposure pathways, the effect of countermeasures, and the associated economic impact;(c) A multi-attribute analysis (MAA) module to evaluate the effectiveness of different countermeasure strategies by accounting for the social, ecological and economic detriments and costs in relation to their benefits;(d) A software system consisting of: (1) software realisation of the mathematical models; (2) a Geographic Information System (GIS) and associated databases to select the aquatic system of interest and, if necessary, the default environmental data required to run the models: (3) a graphical user interface (GUI): (4) an operating system connecting all the above parts.The flexible structures of the environmental models implemented in MOIRA-PLUS DSS give the potential for the application of these models to several other types of pollutants, such as heavy metals. The DSS can be applied to complex water systems comprising lakes, reservoirs and rivers. In this paper, the main principles underpinning the functioning of the DSS MOIRA-PLUS are described and discussed. (C) 2008 Elsevier Ltd. All rights reserved.

EC computer systems in the field of hydrological dispersion modelling and aquatic radioecological research: state of the art, end-user experiences and recommendations for improvements

MOIRA: A Computerised Decision Support System for the Management of Radionuclide Contaminated Freshwater Ecosystems.

Eduardo Gallego, John E. Brittain, Lars Håkanson, Rudie Heling, Dmitry Hofman and Luigi Monte Dpto. Ingeniería Nuclear, Universidad Politécnica Madrid, José Gutiérrez Abascal 2, E-28006, Spain LFI, Zoological Museum, University of Oslo, Sars gate 1, N0562 Oslo, Norway Institute of Earth Sciences, University of Uppsala, Villav. 16, S-752 36 Uppsala, Sweden KEMA Nuclear, P.O. Box 9035, NL-6800 ET Arnhem, The Netherlands Studsvik Eco & Safety AB, S-611 82 Nyköping, Sweden ENEA, Casaccia, C.P. 2400, I-00100 Roma, Italy

The necessity and scope of remediation The accidental introduction of radioactive substances into the environment has caused high and persistent levels of environmental contamination. Aquatic ecosystems are of utmost importance in considering dose to man. In a Nordic perspective, drinking water and fish are the obvious examples. Aquatic systems are also a major pathway for the transport and dispersal of radionuclides from terrestrial fallout, as seen in the aftermath of the Chernobyl accident. Purely local contamination can, through the medium of aquatic systems, lead to widespread consequences. The necessity of reducing doses to man has lead to restrictions in the economical exploitation of the contaminated areas. Moreover, a variety of restoration strategies has been proposed to reduce these restrictions and thus the economic costs: