The objective of the master thesis is to study the undesirable formation of fouling in the cooling system of hydroeletric generators of Fontes Nova Power Plant with the view to propose an alternatives techniques for its mitigation. more specifically, to assess the performance of an antifouling device that exposes the flow to the action of an external electric field. The research was motivated by the perspective of contributing to the understanding of the complex phenomenon associated with the formation and mitigation of fouling and by the challenge of proposin an alternate on-line, non-invasive method, of simple operation, contrasting to conventional of mechanical and chemical cleaning methods that normally offender the environment and requires interruption of the generation. Developed in the context of the project R and D light/aneel Ref. OKE 06-07 entitled Technology for treatment of refrigeration water of the Fontes Nova Power Plant, the research, of quantitative and experimental nature, was developed based on a methodology that assess the of hydrodynamic and thermal performance of the heat exchanger when submitted to the action of the antifouling device studied. The results of the work support the conclusion that the fouling is of a biological nature (biofouling) and that although the non-invasive device inhibits the formation of the unwanted microorganisms that block the exchanger and affect its effectiveness of operation it does not eliminate the problem. An alternative on-line cleaning technique that makes use of abrasive spheres was designed and engineered to clean the heat exchanger in operation.