Structural characterization of nanoscale intermetallic precipitates in highly neutron irradiated reactor pressure vessel steels. (1st March 2016)

• Record Type: Journal Article
• Authors: Sprouster, D.J.; Sinsheimer, J.; Dooryhee, E.; Ghose, S.K.; Wells, P.; Stan, T.; Almirall, N.; Odette, G.R.; Ecker, L.E.
• Is Part Of: Scripta materialia. Volume 113(2016)
• Page Start: 18
• Page End: 22
• Publication Date: 2016-03-01
• Subjects: Reactor pressure vessels -- Precipitation -- Irradiation embrittlement -- X-ray diffraction -- Small angle x-ray scattering; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2015.10.019
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Massive, thick-walled pressure vessels are permanent nuclear reactor structures that are exposed to a damaging flux of neutrons from the adjacent core. The neutrons cause embrittlement of the vessel steel that grows with dose (fluence), as manifested by an increasing ductile-to-brittle fracture transition temperature. Extending reactor life requires demonstrating that large safety margins against brittle fracture are maintained at the higher neutron fluence associated with beyond 60 years of service. Here synchrotron-based x-ray diffraction and small angle x-ray scattering measurements are used to characterize highly embrittling nm-scale Mn–Ni–Si precipitates that develop in the irradiated steels at high fluence. These precipitates lead to severe embrittlement that is not accounted for in current regulatory models. Application of the complementary techniques has, for the very first time, successfully identified the crystal structures of the nanoprecipitates, while also yielding self-consistent compositions, volume fractions and size distributions. Graphical abstract: