Preliminary Occupational Radiation Exposure evaluation related to NET/ITER tritium systems

Abstract

This paper presents the criteria adopted to evaluate Occupational Radiation Exposure (ORE) during normal operation and maintenance of NET/ITER and some results concerning the fuel cycle systems located in the tokamak and tritium buildings. Prompt radiation, activity concentration, and intake situations as well as number of workers, number of events, and exposure time are considered. Many systems and components, whose location in the plant can affect radiological protection during maintenance and/or surveillance, are identified together with the operations needed for each activity. Accidental conditions and equipment failures have been considered in the special maintenance activity when they are due to events with a high probability of occurrence so that such events might be expected during the life of the plant. Some results are reported showing the ORE figures with reference to the main activities. The total man-Sv/y for the systems and activities considered is about 0.5. Such a result, even if very preliminary and incomplete, means that ORE for the tritium systems of a machine like NET/ITER is not negligible and has to be continuously controlled during the design phase.