Structural Evolution of a Zr-2.5 Nb Alloy during Long-Term Low-Temperature Neutron Irradiation

摘要

The channel pipes of the control and safety systems of RBMK-1000 reactors are made of a Zr-2.5 Nb (E125) alloy and must operate for 45 years. The evolution of the alloy structure under the action of long-term low-temperature neutron irradiation is studied. The grain structure of the alloy is shown to be stable; annealing of initial dislocations and the formation of radiation-induced defect take place. Radiation-induced diffusion processes, which lead to a decrease in the niobium content in beta-Nd precipitates and the appearance of new fine-grained precipitates in the alloy matrix, are revealed.