Wear in pressurized water reactors: rod cluster control assemblies

Several components of internal structures in PWRs are affected by the wear under flow induced vibration. For the rod cluster control assemblies (RCCAs), impact/sliding wear must be reduced to master its effects on safety and maintenance costs. Understanding the involved phenomena is based on a chain of models which allow to determine the hydraulic excitation sources, then to compute the vibrational behavior of the RCCA under this excitation and, finally, to estimate the wear volume of material lost under the contacts between the RCCA and its guides. The most efficient remedy to avoid wear consists in surface hardening, with the help of specific coatings or treatments. (authors)