Professor V.I. Makhnenko, scientist A.S. Milenin - PowerPoint PPT Presentation

Title: Professor V.I. Makhnenko, scientist A.S. Milenin


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Remaining Time Assessment of the Steam Generator
Welding Joint ?111-1 of NPP VVER-1000 with
Respect to Detected Cracks.

• Professor V.I. Makhnenko, scientist A.S. Milenin
• E.O. Paton Electric Welding Institute
• of National Academy of Sciences of Ukraine

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• Fig. 1. Scheme of location of the welded joint ?
  111
• body of steam generator
• collector
• nipple ? 1200
• pipe conduit DU-850
• pocket
• A discontinuity (defect).

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• Fig. 2. Defectogram of the welded joint ?111-1 of
  hot collector 1PG-1 of Uzhno-Ukrainskaya
  nuclear power-plant in 1 year after first repair.

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• Fig. 3. Defectogram of ultrasonic inspection of
  the steam generator ? 3, power unit ? 4 of
  Zaporozhskaya nuclear power-plant.

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• Fig. 4. Cartogram of discontinuity ?3 of the
  welded joint ?111-1 (hot collector) PG-3 of
  power unit ?4 Zaporozhskaya nuclear power-plant
  according to the data of the Expert's report
  UkrTsNIITMASh of 13.01.2006.

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• Main Problem permissibility of exploitation of
  the steam generator 4PG-3 of Zaporozhskaya
  nuclear power-plant with a detected defect in
  the region of the welded joint ?111-1 until at
  least the next planned repair (about 1 year).

Questions are to be answered 1. What is the
degree of risk of the generation of the
through-wall crack within the mentioned
period of the exploitation, i.e. the leakage
in the region of the growing defect, that will
lead to the emergency stop of the power
unit? 2. What is the degree of risk of
the spontaneous destruction with the
unpredictable consequences?
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Chemical composition, weight percent. Chemical composition, weight percent. Chemical composition, weight percent. Chemical composition, weight percent. Chemical composition, weight percent. Chemical composition, weight percent. Chemical composition, weight percent. Mechanical properties. Mechanical properties. Mechanical properties. Mechanical properties.
? Si Mn Cr Ni Mo V s?, MPa (200?) s?, MPa (3500?) s0.2, MPa (200?) s0.2, MPa (3800?)
0.134 0.245 0.79 0.25 2.09 0.51 0.02 608 539 500-490 422

• Table 1. Chemical composition and mechanical
  properties of steel 10GN2MFA.

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• Fig. 5. Calculation data about the distribution
  of working stresses szz in the region of the
  pocket depending on pressure in the steam
  generator P6.4 MPa and in the collector PC16
  MPa.

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• Table 2. Stresses szz in the region of the defect
  depending on working pressure 6.4 MPa.

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597 607 617 627 637 647 657 667 r, mm
z, mm
5 86.85 86.16 79.91 69.22 56.83 45.29 36.04 29.33
15 78.68 73.50 67.96 61.79 55.16 48.58 42.70 38.36
25 68.66 64.57 62.28 60.81 58.88 55.92 52.38 49.80
35 60.43 59.21 60.62 62.98 64.64 64.71 63.52 62.49
45 54.47 56.44 61.17 66.49 70.96 73.82 75.29 76.35
55 50.49 55.20 62.84 70.49 77.27 82.77 87.32 91.32
65 48.13 54.79 65.22 74.84 83.40 91.44 99.35 107.16
75 47.85 55.10 68.98 79.36 89.29 99.98 111.13 123.36
85 49.83 65.62 74.51 84.07 95.50 108.96 122.86 138.84
95 130.20 99.19 86.20 91.58 103.41 119.35 135.39 151.88
105 149.72 130.69 126.18 123.01 125.53 134.43 149.64 165.11
115 186.77 180.50 171.04 165.63 160.97 161.55 170.41 183.02
125 220.56 218.10 212.87 209.39 202.83 197.88 197.18 194.71 Seam ?111
135 225.94 224.91 222.37 314.19 210.05 204.41 200.93 196.45
145 168.58 156.43 149.18 153.81 160.58 171.71 182.66 194.74
155 157.85 145.07 145.82 154.03 164.00 175.81 191.44 202.23
165 149.36 139.96 139.98 145.89 158.92 178.75 197.08 212.97
175 140.76 132.79 132.63 141.22 157.36 179.27 203.90 220.17
185 129.27 121.76 123.57 132.08 148.67 173.68 206.78 229.28
195 115.26 108.45 107.98 113.02 126.15 151.31 198.05 249.03
205 100.57 93.09 87.86 85.61 86.63 69.35 86.97 47.65
215 86.60 77.67 69.64 61.95 53.59 40.48 14.86 -48.71
225 73.60 63.97 53.93 42.38 28.19 8.36 -24.61 -63.10
235 62.82 52.91 41.57 28.06 11.29 -10.67 -37.26 -68.46
245 55.26 45.35 33.47 19.13 1.78 -18.47 -41.81 -69.35
255 51.84 41.86 29.84 15.47 -1.39 -20.33 -41.67 -66.95
265 52.50 42.84 30.93 16.66 0.27 -17.83 -38.00 -61.50
275 57.95 48.35 36.39 22.10 5.83 -12.13 -31.81 -54.00
285 68.16 58.42 46.21 31.63 14.85 -3.83 -23.83 -45.07
295 83.11 73.00 60.38 45.24 27.06 6.80 -14.46 -35.42
305 102.56 92.08 79.19 62.15 42.36 20.35 -2.92 -25.70
315 126.93 116.79 103.69 87.15 67.68 46.29 24.70 3.41

• Table 3. Residual stresses sbb (MPa) in the
  region of the welded joint ?111.

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597 607 617 627 637 647 657 667 r, mm
z, mm
5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
25 -1.95 -2.22 -1.82 -1.44 -1.13 -0.94 -0.74 1.08
35 -4.00 -4.55 -3.61 -2.82 -2.36 -2.13 -1.65 0.45
45 -5.28 -5.54 -4.11 -3.38 -3.36 -3.60 -3.51 -2.53
55 -4.79 -4.29 -2.67 -2.92 -4.16 -5.59 -6.68 -8.01
65 -0.98 0.10 0.79 -1.75 -5.09 -8.22 -11.22 -15.72
75 9.25 8.48 5.54 -0.74 -6.46 -11.37 -17.05 -25.03
85 32.00 20.30 9.06 -0.62 -8.14 -14.73 -23.57 -35.33
95 77.13 25.73 10.57 -0.15 -9.62 -17.85 -29.56 -46.46
105 77.15 38.92 1674 2.45 -10.52 -21.20 -35.35 -56.82
115 72.34 55.81 24.91 6.80 -14.09 -30.21 -42.14 -60.70
125 75.02 58.64 31.26 7.83 -12.88 -30.98 -44.28 -70.82 Seam ?111
135 71.89 59.03 39.01 12.81 -8.29 -30.50 -50.93 -78.54
145 71.18 62.12 34.91 18.29 -4.80 -29.46 -57.14 -80.27
155 73.07 55.38 37.69 19.15 -3.37 -30.38 -56.17 -80.64
165 70.90 51.62 37.78 20.00 -2.80 -28.33 -56.96 -77.92
175 70.13 47.18 31.88 17.42 0.28 -24.37 -53.05 -75.94
185 64.36 41.92 28.38 15.90 2.36 -18.57 -48.92 -73.00
195 54.66 37.11 24.34 13.21 3.03 -10.10 -36.41 -74.85
205 45.79 31.68 19.44 8.44 -0.92 -7.59 -7.82 -79.78
215 38.92 26.40 16.02 7.04 -0.66 -10.18 -32.65 -37.64
225 31.55 20.91 11.88 3.72 -4.71 -15.71 -28.52 -9.33
235 23.90 14.94 7.02 -0.47 -8.05 -15.34 -14.46 2.01
245 16.37 9.09 2.42 -3.70 -8.89 -10.27 -4.54 7.53
255 9.65 4.00 -1.18 -5.41 -7.62 -5.51 1.66 10.68
265 4.36 0.13 -3.49 -5.86 -5.90 -2.12 5.18 12.71
275 0.80 -2.26 -4.58 -5.58 -4.41 -0.18 6.75 13.79
285 -0.86 -3.35 -4.65 -4.79 -3.33 0.42 6.62 13.80
295 -0.97 -3.38 -3.77 -3.57 -2.58 0.04 4.96 12.38
305 -0.25 -2.56 -2.11 -2.30 -1.91 -0.55 2.49 8.50
315 0.30 -0.76 -1.01 -1.10 -1.00 -0.35 1.30 -0.28

• Table 4. Residual stresses szz (MPa) in the
  region of the welded joint ?111.

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• Fig. 6. Total stresses szz at the plane of crack
  zconst.

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• Fig. 7. Scheme of the diagram of the static
  corrosive crack growth resistance of
  constructional material
• diagram lg v KI according to experimental data
• idealized diagram.

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Three main stages of the diagram of the static
corrosive crack growth resistance

• first stage (KIltKISCC), when the mechanism of
  the electrochemical corrosion in the growth of
  crack prevails, here the values of the crack
  growth rates are rather small and with reference
  to the case under consideration don't exceed 1-2
  mm/year
• second stage (KISCCltKIltKIC), when the mechanism
  of the hydrogen embrittlement in the growth of
  the corrosion crack prevails, here the values of
  crack growth rates are sufficient enough and for
  constructional steels in the environment of the
  feedwater they can mount to the values 50
  mm/year
• third stage (KIgtKIC) corresponds to the state
  of high risk of the spontaneous growth of crack.

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Steam generator Number of defect Size of defect, mm Size of defect, mm Equivalent crack Equivalent crack Equivalent crack Equivalent crack Scheme of semi-elliptical crack
Steam generator Number of defect Depth, H, mm Width, 2L, mm ?, mm ?, mm KI(G), MPa?m1/2 KI(D), MPa?m1/2 Scheme of semi-elliptical crack
1PG-1 UUNPP 1 63 65 51.2 51.2 59.24 41.18
1PG-1 UUNPP 2 64 85 59.0 59.0 70.18 45.20
1PG-1 UUNPP 3 50 50 40.0 40.0 45.11 35.50
1PG-1 UUNPP 4 40 15 19.6 19.6 26.75 24.34
1PG-1 UUNPP 5 53 70 48.7 48.7 55.75 39.90
1PG-1 UUNPP 6 3 10 3 5 10.60 12.15
1PG-2 UUNPP 1 8 15 8.8 8.8 17.82 16.34 a H, c L, if H ? L if H gt L
1PG-2 UUNPP 2 50 25 28.3 28.3 33.90 29.40 a H, c L, if H ? L if H gt L
1PG-2 UUNPP 3 40 15 19.6 19.6 26.75 24.34 a H, c L, if H ? L if H gt L
1PG-2 UUNPP 4 35 30 25.9 25.9 31.86 28.07 a H, c L, if H ? L if H gt L
1PG-2 UUNPP 5 10 25 10.0 12.5 19.29 19.63 a H, c L, if H ? L if H gt L
1PG-2 UUNPP 6 48 72 47 47 53.45 39.04 a H, c L, if H ? L if H gt L

• Table 6. Sizes of defects and equivalent crack,
  values of KI(G) and KI(D).

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597 607 617 627 637 647 657 667 r, mm
z, mm
5 86.85 86.16 79.91 69.22 56.83 45.29 36.04 29.33
15 75.50 75.63 69.26 64.49 58.55 52.14 46.05 41.63
25 68.20 68.45 64.91 64.39 63.14 60.68 57.95 56.80
35 62.37 63.09 64.14 67.36 69.84 70.84 71.40 72.87
45 58.23 60.14 64.93 71.25 76.84 81.11 85.30 89.65
55 55.09 58.14 65.85 74.87 83.20 90.84 99.05 107.00
65 52.18 56.35 66.10 77.29 88.64 99.82 112.32 124.65
75 51.57 49.30 62.62 78.52 93.53 108.63 124.87 142.11
85 47.39 40.48 66.29 82.29 98.54 116.13 134.80 165.01
95 117.31 88.58 92.87 98.57 112.42 131.06 151.54 168.18
105 143.70 126.20 126.75 129.24 134.88 146.46 165.17 185.42
115 185.38 180.93 175.51 172.17 169.85 172.52 185.24 198.97
125 221.57 220.81 215.14 214.53 210.43 207.71 208.86 205.93 Seam ?111
135 230.44 231.20 227.04 221.01 218.29 213.95 211.89 207.90
145 180.09 170.07 162.40 166.02 172.31 182.80 193.83 205.06
155 172.73 161.81 160.05 167.57 176.30 186.95 200.50 211.66
165 168.01 160.38 159.08 162.07 172.25 189.31 205.42 220.18
175 163.60 157.20 154.44 158.99 171.14 189.31 209.12 227.37
185 157.07 151.07 147.72 151.54 162.86 182.24 208.85 234.07
195 148.68 143.40 136.40 135.45 141.49 158.23 190.94 230.10
205 139.62 133.69 122.10 112.59 105.75 100.36 77.02 54.73
215 131.11 123.77 108.87 93.33 76.20 50.96 10.51 -82.48
225 123.25 115.25 98.03 79.44 57.88 31.75 -23.90 -62.06
235 116.81 108.54 90.09 70.27 47.48 18.45 -21.33 -49.95
245 112.88 104.61 85.88 66.14 43.55 18.15 -13.73 -38.77
255 112.31 104.20 85.90 67.09 46.21 23.71 -3.74 -26.53
265 115.78 107.87 90.44 72.87 53.64 33.22 8.37 -12.58
275 123.55 115.78 99.32 82.86 64.86 45.62 22.24 2.69
285 135.82 128.05 112.48 96.84 79.41 60.43 37.64 19.12
295 152.65 144.70 129.83 114.78 97.09 77.49 54.52 36.55
305 173.98 165.89 151.46 136.02 117.87 97.38 73.43 53.25
315 196.29 186.76 173.96 159.30 141.90 122.15 100.24 87.43

• Table 5. Total stresses sbb (MPa) in case of
  T3000C and working pressure in the region of the
  welded joint ?111-1

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Calculation of the coefficient of stress
intensity KI(D), KI(G) and sref for the
semi-elliptical crack a2c.
If (a/c)lt1.0 and (a/d)lt0.7
where
Sj is an equivalent stress
Here szz(i) is total stress szz according to the
diagram in Fig. 6 at the depth (a/20)i
(i0,1,2,,20) Ci, Di, Ei, Fi are tabulated
weighting functions,

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If (a/c)gt1.0 and 0.2lt(a/d)lt1.0
where







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Mathematical formulation of R6 approach.
, if Lr lt Lrmax
Kr0, if Lr Lrmax
where
sref is the stress that is determined with
external power load without taking into account
the residual stresses and that is able at some
level of the loading to cause the plastic
collapse in the region of the defect under
consideration.
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To calculate sref it was used
where
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(a)
(b)

• Fig. 8. Time dependences of a, c (a) and KI(D),
  KI(G) (b).

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• Fig. 9. Kinetics of reducing of the safety factor
  against spontaneous growth of crack a040 mm,
  c045 mm in time KISCC10 MPam1/2, vm44
  mm/year.

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• Conclusions 1. Numerical analysis of state of
  the steam generator 4PG-3 of
  Zaporozhskaya nuclear power-plant showed that the
  risk of leakage (through
  defect) in the course of year of its exploitation
  (with double time reserve) is
  obviously absent.
• 2. The kinetics of the changing of
  safety factor against the
  spontaneous propagation of crack showed that
  during a year of the exploitation
  the risk of such a spontaneous growth is
  minimal.

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