Radioprotection optimisation during RCCA guide tubes pins replacement in a pressurized water reactor

Initially due to incidental occurrences (Japan in 1978, France in 1982), pins replacement became a systematic and repetitive operation. Between 1983 and 1991, more than 4000 pins has been replaced in France and abroad. The average dose per replacement pin has decreased with a ratio of approximately 8 (from 1,25 mSv/pin in 1982 to 0,14 mSv/pin in 1991). It is due, in a first step, to equipment modification and improvement and, in a second step, to highly skilled personnel, experience feed back and environmental conditions. (author)