The failure cause and solution for the position of fuelling machine ram B

Since pressurized heavy water reactor (PHWR) put into operation, fueling machine ram B had experienced failure for many times, which further cause fueling interruption, schedule change, even overpressure of fueling machine and D₂O leaking when the channel is closed. These article analyses the root cause of ram B failure, with emphasis on main components of bellow, speed reducer, mechanical counter, and potentiometer. Regarding the failure cause, improvement measures are put forward in this article, and thus position failure is reduced significantly. (author)