1. Introduction

Assessing wear damage requires a thorough knowledge of the bodies present during contact, loading and kinematics. Investigations carried out at the Department of Mechanics and Component Technology make it possible to provide coefficients for wear laws relating to wear configurations affecting the components of nuclear power plants. A transient calculation by modal recombination, using the operator DYNA_TRAN_MODAL [U4.54.03], makes it possible to know the kinematics and dynamics of contact for wire structures such as control clusters and steam generator tubes that impact and slide against their guides.

To calculate the wear power, the Code_Aster wear post-processing module, (POST_USURE [U4.67.03]), uses, in a shock node, the generalized coordinate result (tran_gene) from DYNA_TRAN_MODAL. It combines normal forces and sliding velocities according to the method defined in the following paragraph. From the knowledge of the wear power, it is possible to go back to the volumes used by using one of the wear laws proposed in POST_USURE. The coefficients to be used are to be defined by the user or to be searched in a database integrated with the operator.

Secondly, knowledge of the geometry of the internal structures of nuclear power plants makes it possible to calculate the wear depths from the spent volumes.

The operator POST_USURE allows the game pattern to be divided into sectors in order to assign several wear coefficients to the same shock zone to take into account complex geometries. For example, edge contact leads to greater material losses than conformal contact in the case of control clusters.

The table generated by POST_USURE gives the value of the used volumes for several time values.