Using probabilistic methods for solving the problem of ensuring leak tightness of heat exchanger tubes of nuclear power plant steam generators - Probabilistic Safety Assessment for Optimum Nuclear Power Plant Life Management (PLiM) - page 287

ISI, first cycle ( i = 1)

Crack repair Size and detection of

uncertainties

ISI, i i-th cycle

New cracks
- fromWeibull
function
- probable crack
growth rate

Undetected cracks
-define crack size
-probable crack
growth rate

Detected crack
-probable crack
growth rate

End of the i i-th cycle of ISI

9.12 Statistical analysis of the model of crack growth.

￿ ￿ ￿ ￿ ￿

Crack length, mm

9.13 ISI data for crack growth rate (for steam generators
model F).

equal to or greater than 4, the second-degree polynomial must be used. The
crack growth rate is determined by the slope of the regression curve to the
time axis.
Figure 9.16 shows the crack growth rate obtained from the results of
regression analysis. All data show positive crack growth. If there is a
relationship between crack length and its growth rate, the crack growth
rate can be represented as a function of crack size. To find the relationship