Environmental Engineering Reference
In-Depth Information
5.2.3 Assessment of initial and residual
defectiveness and detectability of defects using
inspection results 
Equation [5.8] can be written in the form
A
{
}
[
]
N a
( )=
1
exp
−α −
(
aa
)
,
[5.21]
det
0
a
n
(action range for a a 0 ).
Equation [5.21] can be used to predict the results of flaw inspection if
the function of detectability of defects W ( a ) and the initial defectiveness
N in ( a ) are known.
The equations W ( a ) and N in ( a ) can be estimated, as shown above, on
the basis of analysis of defectiveness at the producer plant in conjunction
with the specific technology of production and direct experimental studies
of detectability of defects in test samples.
However, in most practical cases the equations N in ( a ) and W ( a ) are not
known. Equation [5.21] solves the inverse problem: from the known left-
hand side of equation [5.21] to determine the right-hand side, i.e. determine
the initial defectiveness N in and detectability W .
Indeed, the results of flaw inspection can be used to calculate the
function N det ( a ). This function can be defined as the envelope of the
histogram of inspection results (Fig. 5.37). The problem of determining
N det
￿ ￿ ￿ ￿ ￿
5.37 Curve N det plotted on the basis of inspection results. 
Table 5.9 Characteristics of initial defectiveness of equipment
and inspection methods for the detection of defects
Initial defect
Inspection methods
Equipment
A , mm n -1
n
a 0 , mm
α, mm -1
Cladding VVER-1000
reactor casing
1482
2.17
1
0.034
Parent and welds of
VVER-1000 MCL
241.7
1.58
2
0.114
 
Search WWH ::




Custom Search