[Exposure risk for workers and prevention measures in ordinary and emergency conditions].

The radiological risk assessment and the definition of the radioprotection physical surveillance program applied to a 250 kW (thermal power) research nuclear reactor operated by a large Italian public body. Useful elements for the prevention of personnel exposures, classification criteria for workers, risk reduction methods and optimization of exposures, most common criticalities in plant activities. Analysis of the main operations related to the activities of irradiation and scientific research with an eye to the needs of researchers and one to the indications of prevention. Consolidated intervention methods for ordinary activities and for emergency situations. Detailed examination of the possible unforeseen events or accidents initiators, stopping the assessment at the definition of the source terms related to emergencies inside the plant. Nuclear and conventional causes of accidents and analysis of the radiological consequences. Indications for in-depth-defense and long-term monitoring of the safety of workers, individuals of population and the environment.