Influence of major PWR radiochemical pollutants on dose rates and dosimetry - Importance of efficiency of retention techniques

摘要

The presence of some pollutions in the systems (Co 60, Ag 110m, Sb 124) leads to significant increase of shutdown dosimetry (10 to 30 %) in affected units. Early detection of pollutants, in operation as well as during shutdown, is the best way to set up appropriate solutions. The early replacement of possibly polluting materials, the implementation of a specific chemistry or the choice of specific resins or filters are among the available answers to minimise over-contamination risks in PWR units. At the present time, an optimisation of the chemical and physical properties of the environment during shutdown is being examined, in order to minimise contamination. Studies on filters and resins types and on the impact of purification flowrate are being performed. Minimising systems contamination by retaining pollutants such as Ag 110 m is of the major importance for EDF.