Kinematics and thermodynamics of non-stoichiometric oxidation phase transitions in spent fuel

Conference · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7051308

Stout, R B; Kansa, E J; Wijesinghe, A M

At low temperatures (<200[degree]C), spent fuel from power reactors oxidizes from its UO[sub 2] lattice to a U[sub 4]O[sub 9] lattice but with an oxygen-to-uranium (O/U) ratio of [approximately]2.4. Also, the weight gain time response has a plateau as the O/U approaches 2.4. Part of this response results from a geometrical dependency as a U[sub 4]O[sub 9] oxidation front propagates into grain volumes Of UO[sub 2] It may also be indicative of a metastable, non-stoichiometric U[sub 4]O[sub 9] phase whose existence may inhibit the transition kinetics to the next expected phase Of U[sub 3]O[sub 8]. To gain a mechanistic understanding and to plan future oxidation tests, lattice kinematic and thermodynamic models are developed for lattice deformations and energetics of lattice phase changes (UO[sub 2] [yields] U[sub 4]O[sub 9] [yields] U[sub 3]0[sub 7] [yields] U[sub 3]O[sub 8)] that include zeroth order influences on oxidation kinetics due to interstitial oxygen atoms and vacancies plus interstitial and substitutional actinides and fission decay products in spent fuel.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7051308
• Report Number(s): UCRL-JC-110678; CONF-921101--85; ON: DE93007502
• Country of Publication: United States
• Language: English

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