[en] Flow-induced vibrations in the fuel element assembly of a research reactor were monitored and it was established that long-term monitoring of liner plug vibration can be used to indicate the mechanical integrity of a fuel element if a sufficient case history is established. The vibrational behaviour of a number of fuel elements with different integral modifications were examined but only a relatively small change in vibration levels was obtained. The overall vibration levels were most effectively decreased by installing flow straighteners in the exit nozzles of the plenum chamber. (author)