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 313

Depth of defect, % to wall thickness

9.30 Results of evaluation of the detectability of ECT (eddy current
testing) and pneumo-hydraulic inspection (PHI) of PGV-1000 heat
exchanger tubes using the SPM-96 results: 1 - ECT in SPM-96;
2 - PHI; 3 - HT+PHI; 4 - ECT in SPM-98 (specified on the basis of
data from SPM-98).

Table 9.11 Comparison of the sizes of defects identified during ECT and MI
of HET of steam generator No. 2 at the Balakovo NPP

Number of HET
(according to AER)

Depth of defect a , %
of pipe thickness s

Inaccuracy

Steam
generator
No.

Location of
defect

( a ECT - a MI ), % of s

Row Column ECT MI

- 60

2 NR3; 000 94 53 +41

92 60 NR3; 000 80 ≈ 1 +79

92 60 NR6; 000

-

100

- 100

1

￿ ￿ ￿ ￿ ￿

1 61 NR2; 000

-

100

- 100

Between HP4-
HP5

- - 88 1 61 88

NR3; - 320

102 60 80 2 78

102 60 NR3; 000

-

100

- 100

3

- 60 NR3; - 290

96 100 100 0

- 60 - - 100 96 NR3; 000 100

Comment:
1. (+) and (-) in the last column indicate over-rejection and under-rejection,
respectively according to the result of eddy current testing (ECT).
2. NR3 (6;2) is the spacing lattice No. 3 (6;2); 320 (290) is the distance from the
lattice to the defect, to collector (-) and from collector (+)
3. AER is the organisation contracted to carry out ECI
4. MI - metallographic investigatons