Interaction layer growth correlations for (U-Mo)/A1 and Si-added (U-Mo)/A1 dispersion fuels.

The interaction layer (IL) growth correlation of (U-Mo)/Al dispersion fuel for in-reactor tests is considerably different from that for out-of-pile tests because it contains factors that enhance diffusion kinetics by fission damage in the IL. This enhancement during irradiation was formulated by a combination of the fission rate and fission-fragment damage factor in the IL. Using a computer code (TRIM), fission damage factors were obtained as a function of the thickness and Al-composition of the IL. As a result of data fitting, the model correlation was set as a function of four major factors: fission rate, fission-damage factors, temperature and time. One important change from the old model used in the PLATE code is that the new one has the squareroot dependence on the fission rate, whereas the old one has a linear dependence. The preliminary PIE results from RERTR-6 have shown a significant reduction in the IL thickness for the Si-added plates as well as prevention of pore formation. The reduction in IL growth followed an exponential decay function of the Si-content.