rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Phase stability and thermodynamic assessment of the Np-Zr system
  name:
    name part: Bajaj, Saurabh.
    role:
      role term: creator
  name:
    name part: Cagin, Tahir
    role:
      role term: thesis advisor.
  name:
    name part: Arroyave, Raymundo
    role:
      role term: thesis advisor.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2012
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: remote
    extent: 1 online resource.
  abstract: Metallic fuels have an important role to play in "fast breeder" Gen-IV type nuclear reactors, and U-Pu-Zr is one of the prototypical systems. Because of the variability in fuel chemistry during burn-up, it is important to understand the effect of minor actinides and fission products on phase stability. Within this framework, we present a study on phase equilibria in the binary Np-Zr alloy system on which little work has been published. To resolve the contradictory reports on the ordering/ clustering trends of the bcc phase, a thermodynamic study is performed using the CALPHAD method. The calculated Np-Zr phase diagram is consistent with two sets of data: formation enthalpies of the bcc phase that are calculated with ab initio KKR-ASA-CPA electronic-structure method and lattice stabilities of solution phases obtained from first-principles technique. Another important feature in the Np-Zr alloy system is the non-stoichiometric delta-NpZr2 phase that forms in a hexagonal C32 structure similar to the delta-phase in the U-Zr system and the w-phase in pure Zr. An increase in the homogeneity range of the delta-phase when going from Pu to Np and to U is attributed to a lowering of its heat of formation that is caused by an increase in d-band occupation. Two different possibilities for the stability of the delta- and w- phases have been proposed in the present work. Additionally, calculated changes in enthalpy versus temperature are plotted for two alloy compositions of the Np-Zr system to guide future experimental work in resolving important issues in this system. Finally, an ab initio study, implemented with the L(S)DA U formalism, is performed for pure Np that reveals a transition from a non-magnetic to a magnetic state at a critical U parameter.
  note: by Saurabh Bajaj.
  note: "Major Subject: Mechanical Engineering"
  note: Electronic resource.
  note: Master of Science Texas A&M University 2010 http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8773
  note: Includes bibliographical references.
  note: Text (Thesis)
  subject:
    topic: Major mechanical engineering
  subject:
    topic: CALPHAD
  subject:
    topic: Metallic fuels
  subject:
    topic: phase diagram
  subject:
    topic: electronic-structure
  subject:
    topic: first-principles
  subject:
    topic: fast-breeder
  subject:
    topic: ab initio
  subject:
    topic: phase equilibria
  subject:
    topic: L(S)DA U
  identifier: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8773
  record info:
    record content source: TXA
    record creation date: 120307
    record change date: 20151202151705.0
    record identifier: in00002740604