Results from visual inspection of heterogenic weld at SG16 from April 2002

In the period 2002-2003 we focused on the „Phase analyses of corrosion induced damage of feed water pipelines of SG 16 near the heterogenic weld". In frame of this study visual inspections as well as original "in situ" specimens scrapping was performed. Conclusions from visual inspections (performed at 19.4.2002 and 29.4.2002 at SG16) were the following:

SG16 was dried under the level of primary pipelines bundle and decontaminated. During the visual inspection of SG16 internal surface as well as hot and cold collectors (after 23 years of operation) no defects or cracks were identified. The SG16 was in excellent status with minimal thickness of corrosion layer or other deposits. For comparison to our previous experience from visual inspections from 1998, the SG16 was in better condition than SG35 or SG46 (14 and 13 years in operation, respectively). Moreover, the radiation situation after decommissioning procedures was two times better.

Visual inspection on 29.4.2002 was focused on heterogenic weld, which connects the feed water pipeline of carbon steel (GOST 20K) to a new feed water pipeline system designed from austenitic steel (CSN17248). Several samplese were taken for MS analyse from the weld as well as surrounding area in form of powder or small particles (samples description is in Table 5 and in Figs 8, 9). The heterogenic weld was well polished.

After visual inspection, the evaluation of corrosion phase composition of samples closed to heterogenic weld was performed. MS results are summarized in Table 6.

Number of samples

Samples description

2.11

Heterogenic weld

2.12

Feed water pipeline (GOST 20), 10 cm from heterogenic weld

2.13

Feed water pipeline (GOST 20), about 40 cm from heterogenic weld, just closed to the SG16 internal body surface.

2.14

Internal body surface, about 1 m under the place of feed water pipeline inlet

2.15

Internal body surface, about 50 cm over the place of feed water pipeline inlet

Table 5. Specimens description

Fig. 8. SG16 with marks and description of places, where MS specimens were taken

Fig. 9. SG16 cross section with indicated places where specimens were taken

Haematit

Magnetite

Mag.

Metalic iron

Dublet/ singlet

Sample

H1

QS1

IS1

Arel1

H2

IS2

Arel2

H3

IS3

Arel3

total

H4

IS4

Arel4

QS4

IS4

Arel4

(T)

(mm

/s)

(mm

/s)

(%)

(T)

(mm

/s)

(%)

(T)

(mm

/s)

(%)

(%)

(T)

(mm

/s)

(%)

(mm

/s)

(mm

/s)

(%)

2.11

51,9

-0,18

0,25

8,0

49,0

0,17

3,8

45,9

0,57

8,0

11,8

33,0

-0,11

12,8

-0,19

67,4

2.12

51,6

-0,21

0,26

75,9

49,0

0,16

9,1

45,8

0,56

14,1

23,2

0,40

0,21

0,9

2.13

51,6

-0,21

0,26

77,2

49,0

0,17

9,2

45,9

0,57

12,9

22,1

0,40

0,21

0,7

2.14

51,6

-0,21

0,26

41,1

49,0

0,16

22,0

45,8

0,55

36,9

58,9

2.15

51,8

-0,21

0,26

51,7

49,1

0,17

18,3

45,9

0,54

29,2

47,5

0,40

0,21

0,8

Accuracy

±0,1

±0,04

±0,04

±2

±0,1

±0,04

±0,1

±0,1

±0,04

±2

±2

±0,1

±0,04

±2

±0,04

±0,04

±2

Table 6. Mossbauer spectra parameters

Hematite

Magnetite

Dublet

Sample

H1

QS1

IS1

Arel1

H2

IS2

Arel2

H3

IS3

Arel3

Spolu

QS1

IS1

Arel1

(T)

(mm

/s)

(mm

/s)

(%)

(T)

(mm

/s)

(%)

(T)

(mm

/s)

(%)

(%)

(mm

/s)

(mm

/s)

(%)

2.16

51.6

-0.21

0.26

66.4

49.1

0.17

12.1

45.9

0.56

19.6

31.7

0.53

0.23

1.9

2.17

51.6

-0.21

0.26

80.8

49.1

0.16

6.6

46.0

0.55

11.5

18.1

0.47

0.21

1.1

2.18

51.6

-0.21

0.26

33.4

49.0

0.16

22.6

45.9

0.55

42.9

65.5

0.52

0.09

1.1

2.19

51.6

-0.21

0.26

40.3

49.0

0.16

20.5

45.9

0.56

38.0

58.5

0.52

0.13

1.2

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