The microstructure and thermodynamic behavior of as-cast U-24Pu-15Zr: Unexpected results and recommendations for U-Pu-Zr fuel research methodology

Jacob Hirschhorn, Assel Aitkaliyeva, Cynthia Adkins, Michael Tonks

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Minor actinide transmutation fuels, of which U-Pu-Zr is one of the most promising, have been the subject of renewed interest for fast reactor applications. Unfortunately, we lack the understanding necessary to make quantitative, mechanistic predictions about the complex phase behaviors exhibited by U-Pu-Zr. This prevents the efficient development and implementation of U-Pu-Zr fuels. Herein, we use state of the art experimental and mesoscale simulation techniques to examine and predict the behavior of U-24Pu-15Zr (weight percent). Experimental and simulated microstructural and phase stability results are compared to one another and to accepted reference data. Experiments revealed a heterogeneous microstructure composed of αZr, ZrO 2 , δ βPu, and ζ at room temperature. The unexpectedly high ratio of βPu to ζ is believed to arise from non-equilibrium and surface effects, as both passivation and Pu and Zr segregation were observed in the samples. A modeling technique based on the overall bulk free energy is devised to estimate the extent of a microstructure's departure from equilibrium. Agreement between the datasets is used to justify a set of recommendations for the further study of U-Pu-Zr fuels. These address deficiencies in our fundamental knowledge, fuel fabrication and handling techniques, characterization methods and procedures, modeling capability, and use of coupled experiments and mesoscale simulations.

Original languageEnglish (US)
Pages (from-to)80-94
Number of pages15
JournalJournal of Nuclear Materials
Volume518
DOIs
StatePublished - May 2019

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

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