Three reactor blocks of WWER-440 type have been put into operation at the Paks Hungary, nuclear power plant (NPP) from 1983. In the frame of the reactor vessel surveillance program accelerated capsules (LF > 10) have been used. Three surveillance sequences with the first reactor block and two sequences with the second have been evaluated to date.

Surveillance neutron dosimetry analysis and the results of related investigations (ex-vessel dosimetry, additional capsule irradiation) performed in order to improve the life-time assessment of the reactor pressure vessel are presented. Very good agreement between the dpa and fast neutron flux (E > 0.5 MeV) lead factors (LF) was found for the spectrum of interest. The results obtained to date show that the reactor can be safely operated until the end of its designed service life (40 years).