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Title: Structural characterization of nanoscale intermetallic precipitates in highly neutron irradiated reactor pressure vessel steels

Here, 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 increases with dose (fluence or service time), as manifested by an increasing temperature transition from ductile-to-brittle fracture. Moreover, extending reactor life requires demonstrating that large safety margins against brittle fracture are maintained at the higher neutron fluence associated with 60 to 80 years of service. Here synchrotron-based x-ray diffraction and small angle x-ray scattering measurements are used to characterize a new class of highly embrittling nm-scale Mn-Ni-Si precipitates that develop in the irradiated steels at high fluence. Furthermore, these precipitates can lead to severe embrittlement that is not accounted for in current regulatory models. Application of the complementarity techniques has, for the very first time, successfully characterized the crystal structures of the nanoprecipitates, while also yielding self-consistent compositions, volume fractions and size distributions.
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Univ. of California, Santa Barbara, CA (United States)
Publication Date:
Report Number(s):
BNL-108275-2015-JA; BNL-111938-2016-JA
Journal ID: ISSN 1359-6462; R&D Project: LS001
Grant/Contract Number:
SC00112704; AC02-98CH10886; SC0012704
Accepted Manuscript
Journal Name:
Scripta Materialia
Additional Journal Information:
Journal Volume: 113; Journal Issue: C; Journal ID: ISSN 1359-6462
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC); BNL Program Development
Country of Publication:
United States
36 MATERIALS SCIENCE; reactor pressure vessels; precipitation; irradiation embrittlement; x-ray diffraction; small angle x-ray scattering
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1341516; OSTI ID: 1359850