Diffusion behavior of Pu and Am in fuel

Sato, Isamu; Tanaka, Kosuke  ; Tanaka, Kenya

The diffusion coefficients of Pu and Am in UO fuel have been evaluated by use of a diffusion couple, in which a UO pellet and an Am containing MOX fuel contact each other. The heating temperature, time and atmosphere is 1650C 4.5h and Ar gas, respectively. We could catch the diffusion behavior of Pu and Am in UO. The value of diffusion coefficient of Pu and Am were evaluated to be 4-610m/sec. On the other hand, we try to estimate the tracer-diffusion coefficients with the molecular dynamics. Around 2000 K (close to the heating temperature), the coefficient was near 10m/sec, which was agree with the value from Matzke's evaluation. This indicates the possibility of molecular dynamics for estimation of the diffusion coefficient. The gap between the coefficient from the test and reference (or estimation) might result from the affection of grain boundaries.