Vessel investigation program of "CHOOZ A" PWR reactor after shutdown

In October 1991 the CHOOZ A PWR plant, operated by the French and Belgian company SENA, was shut down after 24 years. It was the first PWR shutdown in France. According to the EDF life duration project it was decided to perform an examination program on samples taken from the wall of the vessel in order to complete the feedback. The results obtained show the following: The embrittlement measured by the pressure vessel surveillance program is representative of that of the Shell determined at different axial and angular locations for the 1/4 of the internal thickness. This observation is consistent with the relative homogeneity of the embrittling elements (Cu, P, Ni) throughout the entire Shell, The mechanical properties evolution through the wall thickness of the Shell measured after irradiation is interpreted in relation with fluence variation and unirradiated mechanical properties profile through the thickness, The comparison of direct toughness measurement with the French code RCCM evaluation confirms the safety nature of the conventional approach. For the weld, after an irradiation damage of 2 10(19) n.cm(-2) (E > 1MeV), a margin of the order of the irradiation effect seems to exist.