Comparison of the high Ni VVER-1000 weld microstructure under the primary irradiation and re-irradiation

This paper presents the first comparative experimental assessment of the microstructures of the same surveillance specimens of VVER-1000 high Ni weld: after the primary irradiation, recovery annealing and re-irradiation in the same industrial NPP (Balakovo NPP unit 1) to assess the possibility of it...

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Bibliographic Details
Published in:Journal of nuclear materials 2020-11, Vol.540, p.152384, Article 152384
Main Authors: Kuleshova, E.A., Gurovich, B.A., Fedotova, S.V., Zhuchkov, G.M., Frolov, A.S., Maltsev, D.A., Saltykov, M.A., Dementyeva, M.M.
Format: Article
Language:English
Subjects:
Annealing
Atom probe tomography
Auger electron spectroscopy
Dislocation loops
Fast neutrons
Grain boundaries
Grain Boundary Segregation
High Ni weld
Irradiation
Lifetime extension
Light water reactor
Neutron irradiation
Precipitates
Radiation
Radiation effects
Radiation hardening
Radiation-induced precipitation
Re-irradiation
Reactor pressure vessel steel
Recovery
Recovery annealing
Surveillance specimens
Transmission electron microscopy
Welding
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Summary:This paper presents the first comparative experimental assessment of the microstructures of the same surveillance specimens of VVER-1000 high Ni weld: after the primary irradiation, recovery annealing and re-irradiation in the same industrial NPP (Balakovo NPP unit 1) to assess the possibility of its lifetime extension after annealing up to 60 years. Therein, studies of both the initial (carbides) and radiation-induced hardening phases (precipitates and dislocation loops), and the behavior of grain boundary segregation as well are presented. It has been shown that the microstructures of high Ni VVER-1000 weld after the primary irradiation and re-irradiation after recovery annealing up to the close values of fast neutron fluences are identical: the characteristics of both initial and radiation-induced hardening phases, as well as grain boundary segregation, are the same. •VVER-1000 high Ni weld is studied by APT, TEM, AES in primary and re-irradiated states.•parameters of hardening elements are equal in primary and re-irradiated states.•Grain boundary segregation level is the same in primary and re-irradiated states.•Re-embrittlement rate of high Ni VVER-1000 welds should not exceed the primary one.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2020.152384