that of the unprocessed matrix; mass fraction is one of the factors used in assessing the suitability of the waste form. The extent of partitioning of these radioelements between the two intergrown phases has not been established.

The release rate for the cladding-metal waste form is a function of the matrix dissolution rate, the matrix surface area, and the mass fraction of nuclide within the metallic matrix. Standard techniques and test protocols for the measurement of matrix dissolution rates for nuclear waste forms are well established. The performance of this metal-matrix waste form has had only preliminary laboratory study, and a bulk dissolution rate of 5.0 g/m2 per yr has been reported.7 This value compares with a measured dissolution rate for the UO2 matrix of PWR spent fuel of about 3 g/m2 per yr under oxidizing conditions.8 The mass fraction of nuclides within the cladding waste form depends on the type of fuel, the fuel burnup, and the efficiency of the electrometallurgical separation.

7  

Ibid.

8  

W.J. Gray and D.M. Strachan, Mat. Res. Soc. Symp. Proc., Vol. 212, pp. 205-212, Materials Research Society, Pittsburgh, Penn., 1991.



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