In:
Nuclear Energy and Technology, Pensoft Publishers, Vol. 7, No. 3 ( 2021-09-23), p. 239-244
Abstract:
Quantum-mechanical methods are used to assess the energy barriers to dissociation and recombination reactions of UF 6 ↔ UF 5 + F and UF 6 ↔ UF 4 + F 2 . The energy characteristics of these reactions are found to be strongly asymmetric: the dissociation reaction barriers exceed the recombination reactions barriers by more than 4 eV. The equilibrium atomic configurations of F 2 , UF 4 , UF 5 and UF 6 have been determined using precision quantum mechanical calculations. The U-F bond lengths obtained as a result of the calculations are in good agreement with experimental data. It was found that the decay reaction UF 6 → UF 5 + F is either barrier-free, or the energy barrier for such a reaction is less than the resolving power of the method (~ 0.1 eV). For the decay of UF 6 → UF 4 + F 2 , there is an energy barrier with a height of about 0.3 eV. An initial approximation was proposed for the arrangement of UF 6 atoms in order to find the saddle points of the UF 6 dissociation reactions. In this initial configuration, all 7 atoms of the UF 6 molecule are located in the same plane. The F atoms are located at the vertices of a regular hexagon, and the U atom is at the center of such a hexagon. The results of this work can be used to determine the constants of thermal reactions of dissociation and recombination UF 6 ↔ UF 5 + F и UF 6 ↔ UF 4 + F 2 . These constants are necessary for modeling the physicochemical processes occurring during the enrichment of spent nuclear fuel (SNF).
Type of Medium:
Online Resource
ISSN:
2452-3038
DOI:
10.3897/nucet.7.74152
DOI:
10.3897/nucet.7.74152.figure1
DOI:
10.3897/nucet.7.74152.figure2
DOI:
10.3897/nucet.7.74152.figure3
DOI:
10.3897/nucet.7.74152.figure4
DOI:
10.3897/nucet.7.74152.figure5
Language:
Unknown
Publisher:
Pensoft Publishers
Publication Date:
2021
detail.hit.zdb_id:
2858592-6