Evolution of the nanostructure OF VVER-1000 RPV materials under neutron irradiation and post irradiation annealing
- ORNL
- Russian Research Center, Kurchatov Institute, Moscow, Russia
A high nickel VVER-1000 (15Kh2NMFAA) base metal (1.34 wt% Ni, 0.47% Mn, 0.29% Si and 0.05% Cu), and a high nickel (12Kh2N2MAA) weld metal (1.77 wt% Ni, 0.74% Mn, 0.26% Si and 0.07% Cu) have been characterized by atom probe tomography to determine the changes in the microstructure during neutron irradiation to high fluences. The base metal was studied in the unirradiated condition and after neutron irradiation to fluences between 2.4 and 14.9 x 10{sup 23} m{sup -2} (E > 0.5 MeV), and the weld metal was studied in the unirradiated condition and after neutron irradiation to fluences between 2.4 and 11.5 x 10{sup 23} m{sup -2} (E > 0.5 MeV). High number densities of 2-nm-diameter Ni-, Si- and Mn-enriched nanoclusters were found in the neutron irradiated base and weld metals. No significant copper enrichment was associated with these nanoclusters and no copper-enriched precipitates were observed. The number densities of these nanoclusters correlate with the shifts in the {Delta}T{sub 41 J} ductile-to-brittle transition temperature. These nanoclusters were present after a post irradiOffice of Science (US)C, but had dissolved into the matrix after 24 h at 450 C. Phosphorus, nickel, silicon and to a lesser extent manganese were found to be segregated to the dislocations.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Shared Research Equipment Collaborative Research Center
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 949993
- Journal Information:
- Journal of Nuclear Materials, Vol. 385, Issue 3; ISSN 0022-3115
- Country of Publication:
- United States
- Language:
- English
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