1. Reactor Pressure Vessel Cladding
Gillemet

2. Ferenc Gillemot (1939) (PhD) studied Mechanical Engineering and continued it for a post-degree specialization in Welding Technology at Technical University of Budapest. He gained his PhD in low cycle fatigue. He is member of the Hungarian Academy of Engineering and several international organisation, member of the editorial board of two international journals. His professional fields are radiation embrittlement, fracture mechanics, RPV integrity. He is retired and working as a consultant for the Atomic Energy Research Institute Budapest, workpackage leader in the LONGLIFE FP7 project.

3. 1 What is the role of the RPV cladding?

4. Reactor pressure vessel The blue line outside is the vessel wall covered inside with cladding against corrosion.

5. 2. What type of material is used for RPV cladding?

6. The grain size of the welded austenitic cladding is large compared with the base material

7. Table 1. Chemical composition of different claddings
Type
Layer
Composition
WWER 440 C%
Si%
Mn% P% S%
Cr%
Mo%
Ni%
Cu%
Nb% 1
0,056
0,86
1,16
0,015
0,004
22,8 -
13,3
0,06 2
0,034
0,60
1,46
0,013
18,2
9,3
0,07
0,88
French
0.048
0.39
1.84
0.016
18.08
0.21
10.45
0.065
0.66
1.50
0.012
19.05
0.138
9.68
0.017
0.29
1.90
0.026
18.72
0.07
10.49
0.030
0.71
1.53
0.014
19.90
0.069
10.16

8. 3. What technology is used for clad a vessel?

9. Welding of the cladding with submerged arc welding using strip electrode

10. 4. What nondestructive testing methods can be applied for prove the integrity of the cladding?

11. Ultrasonic testing of cladding on blocks cut from a shut down WWER reactor

12. 5. Which destructive testing methods can be applied to study the ageing of cladding?

13. Paralell necking of the welded cladding due to the rough grain sizes

15. The effect of irradiation on the tensile properties of the first and second layer of WWER cladding

16. Paralell necking of the welded cladding due to the rough grain sizes

17. 6. What are the typical mechanical properties of the as-received and aged cladding?

18. Tensile diagrams of as received and irradiated cladding tested at room temperature and at 300°C.

19. The effect of irradiation on the tensile properties of the first and second layer of WWER cladding

20. The effect of irradiation on the elongation and reduction of area of the first and second layer of WWER cladding

21. Reduction of the Charpy upper shelf energy and increase of transition temperature as the effect of irradiation.
O= as received = 5.5*1021 n/cm2 irradiation at 325 °C ▲= 2.1*1022 n/cm2 E>0.5MeV irradiation at 265°C.[5]

22. Charpy impact test results on as-received and irradiated RPV cladding

23. 7. Effect of the chemical composition and delta ferrit on the irradiation embrittlement of the

24. Irradiation hardening of 308 type cladding in the function of the ferrite content

25. 8. How to calculate the thermal stresses caused by the cladding?

26. Finite element model of a clad RPV nozzle

27. 9. What is the role of the cladding in the RPV integrity assessments?

28. Thermal stresses during a PTS event in an RPV wall
Thermal stresses during a PTS event in an RPV wall. The maximum stresses are occur in the cladding

29. 10. Open Issues

30. 11. Consolidated Conclusions