Physico–statistical approach taking defects into account and using binomial distribution - Probabilistic Safety Assessment for Optimum Nuclear Power Plant Life Management (PLiM) - page 102

Initial data

Division of structure into elements for
analysis of defect propagation

Division of structure into cells for
analysis of defect propagation

Collection of data for
investigated element

Collection of data for
investigated cell

Analysis of indeterminacy of initial data

Determination of probability of defect
nucleation on basis of fatigue-mechanical
and corrosion mechanisms in investigated
cell

Correction of size distribution
of defects for given elements
on basis of results of growth
of calculated defects

Distribution on basis of
mechanisms of critical defect
growth in relation to conditions in
which the element operates

Nucleation of new defects on basis of
cumulation of fatigue, mechanical and
corrosion damage

Critical
defect
growth acc.
to elastic-
plastic
failure
criterion

Corrosion-fatigue growth
of defects

Critical
defect
growth
acc. to
large-scale
failure
criterion

Critical
defect
growth acc.
to ductile
failure
criterion

Correction of size distribution of defects
for given elements onbasis of nucleation
of new defects
Correction of distribution of number of
defects for given elements onbasis of
nucleation of new defects

Ye s

No

Ye s

No

No

Ye s

Correction of size distribution of defects
for given elements on basis of results of
inspection of metal
Correction of distribution of number of
defects for given elements on basis of
results of inspection of metal

Determination of equivalent diameter nominal on basis
of size of continuous defects

￿ ￿ ￿ ￿ ￿

Determination of probability of leaks of
equivalent diameter nominal for a given
element taking indeterminacy into account

Determination of probability of large-scale failure
in given element taking indeterminacy of initial data
into account

Determination of probability of leaks of equivalent
diameter nominal for a given structure

Determination of probability of large-scale failure
of investigated structure

Determination of safety
indices

Determination of
maintainability parameter

Determination of endurance parameters

4.2 Enlarged flow diagram of the definition of the rate of failure
and the transition to the limiting state.