Physico–statistical models based on the residual defectiveness of structural materials - Probabilistic Safety Assessment for Optimum Nuclear Power Plant Life Management (PLiM) - page 160

performed, or the function of residual defectiveness if inspection is carried
out, ( a, c ) max is the maximum possible size of the defects in the structure; a
is the size of the defect in the direction of the wall thickness of the vessel,
a max = s , where s is the wall thickness. For c , the maximum value c max is
the value at which the probability of existence of a defect with c = c max
is equal to 0. For a circumferential defect c max may be equal to the length
of the perimeter of the pipe or the cylindrical part of the pressure vessel.
The denominator in [5.23] has the meaning of the normalisation factor. It
is natural to assume that the integral in the denominator is equal to 1 and
the boundary values ( a d , c d ) should be sought from the condition:
a)
b)
2c, mm
c)
￿ ￿ ￿ ￿ ￿
d)
a , mm
5.40 The probability function of the existence of defects in the
cladding of the casing (a, b) and MCP Du850 of the VVER-1000
reactor (c, d): 1) initial state, 2) after input control, 3) after first,
second, third inspection (a, b) and first (c, d) inspection.