Physico–statistical models based on the residual defectiveness of structural materials - Probabilistic Safety Assessment for Optimum Nuclear Power Plant Life Management (PLiM) - page 187

P f

5.53 Dependence of the probability of failure on D 0.5 .

P f

￿ ￿ ￿ ￿ ￿

5.54 Dependence of the probability of failure on a 0 .

elements of nuclear power plant. This kind of ageing is further explained
below.
At Russian nuclear power plants special attention is paid to experimental
studies of the ageing of structural steels during their operation. These
studies are performed on a regular basis every 100 000 hours of service,
including after 150 000 and 200 000 hours of operation, and in some cases
with a defect in the metal.
A list of major steel plants with VVER-440, VVER-1000 and RBMK-
1000 reactors and the extent of studies of these during operation are shown
in Table 5.11.
The results of investigation of the mechanical properties of the steel of
the main pipeline of the VVER-440 reactor - 0Kh18N12T - are given as
an example.