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Segregation of fission products to surfaces of UO(sub 2).

DE2001769009

Publication Date	2000
Personal Author	Stanek, C.
Page Count	9
Abstract	In order to predict the release rates of fission products from U02 nuclear fuel, it is necessary to determine the energetic associated with their segregation from the bulk to surfaces. Here segregation is determined by calculating the total energy of a simulation repeat unit which includes a fission product, as a function of the distance of the fission product from the surface. We have investigated the possibility that specific fission products segregate preferentially to Certain surfaces. In particular,Ce4+ and Zr4+ segregate to the (100) surface, while Ba2+ and Sr2+ Segregate to the (111) surface. Two issues make these calculations more complex. First, charged defects need to be compensated by oxygen vacancies. For example, divalent Ba2+ and Sr2+ substituting on uranium sites are compensated by a single oxygen vacancy. Second, certain surfaces, such as the (100), are inherently unstable, but can be stabilized by oxygen vacancies. Arrangements of these surface defects lead to complex surface structures that effect segregation energetic.
Keywords	Fission products Segregation Uraninites
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	77I - Reactor Fuels & Fuel Processing
Corporate Authors	Los Alamos National Lab., NM.; Department of Energy, Washington, DC.
Document Type	Conference Proceedings
NTIS Issue Number	200124
Contract Number	W-7405-ENG-36

Segregation of fission products to surfaces of UO(sub 2).

Segregation of fission products to surfaces of UO(sub 2).
DE2001769009

Publication Date	2000
Personal Author	Stanek, C.
Page Count	9
Abstract	In order to predict the release rates of fission products from U02 nuclear fuel, it is necessary to determine the energetic associated with their segregation from the bulk to surfaces. Here segregation is determined by calculating the total energy of a simulation repeat unit which includes a fission product, as a function of the distance of the fission product from the surface. We have investigated the possibility that specific fission products segregate preferentially to Certain surfaces. In particular,Ce4+ and Zr4+ segregate to the (100) surface, while Ba2+ and Sr2+ Segregate to the (111) surface. Two issues make these calculations more complex. First, charged defects need to be compensated by oxygen vacancies. For example, divalent Ba2+ and Sr2+ substituting on uranium sites are compensated by a single oxygen vacancy. Second, certain surfaces, such as the (100), are inherently unstable, but can be stabilized by oxygen vacancies. Arrangements of these surface defects lead to complex surface structures that effect segregation energetic.
Keywords	Fission products Segregation Uraninites
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	77I - Reactor Fuels & Fuel Processing
Corporate Authors	Los Alamos National Lab., NM.; Department of Energy, Washington, DC.
Document Type	Conference Proceedings
NTIS Issue Number	200124
Contract Number	W-7405-ENG-36