PSI - Issue 28

L.A. Igumnov et al. / Procedia Structural Integrity 28 (2020) 2086–2098 L.A. Igumnov, I.A. Volkov/ Structural Integrity Procedia 00 (2019) 000–000

2094

9

At all stages, the load acting on the bottom of the reactor vessel from the hydrostatic effect of the meltdown was modelled. It is to be noted that, in constructing the analytical model, the effect of the zone of the elliptical bottom was taken into account, in which the material, due to heavy meltdown, practically does not resist deformation. For this reason, the thickness of the elliptical bottom in the analytical model was reduced by the depth of the meltdown zone (T > 1200 ◦C).

Fig. 8. Temperature field distribution in the reactor vessel in the condition of a serious accident.

Table 1 Physical–mechanical characteristics and material parameters of the MDM model of steel 15H2NMFA

T , °C

K , MPa

G , MPa

ω f

1 c g , MPa

2 c g , MPa

(0) c  , 1/MPa.hr 0.000045 0.00026 0.0002 0.00027

(1) c  , 1/MPa.hr 0.00009 0.00052 0.000053 0.00027

c C , MPa

W a , MJ/m 3

W f , MJ/m 3

600 800 900

138000

63500 16000 30800

110

30000

1000

26

11.2

0.8 0.8 0.8 0.8

34700 66700

29

3500 1000

350 300 100

7

3.7

9

2.6

1.24 0.21

1200

9170

4230

1.5

100

0.65

Fig. 9. Creep curves for temperature T 900 ◦ C and stresses σ 11 = 20; 22 and 26.5 MPa.

Fig. 10. Creep curves for temperature T = 1200 ◦ C and stresses σ 11 = 4 . 5; 5.4 and 6.3 MPa.