RRFM 2009 Transactions - European Nuclear Society

RERTR-9A and -9B. From the RERTR-9A, R3R108 (C2 with 5%Si) and R2R078 (C3 with 2%Si)
achieved plate-average fuel particle BU of 64% LEU Equiv. for 98 EFPD. From the RERTR-9B,
R2R088 (B6 with 2%Si) and R6R018 (B7 with 3.5%Si) have plate-average BU of 100% LEU
Equiv. for 115 EPFD.
3. Results
The effect of the Si addition to the matrix for suppressing IL growth is clearly distinguishable
when we compare the microstructures of the post-irradiation metallographs of pairs of plates
irradiated side-by-side. As shown in Fig. 2, the IL thickness and microstructure are remarkably
different between the left-hand-side plate and the right-hand-side plate. The low Si-content plate
on the left-hand-side consistently shows a thicker IL than the one with 2% Si-content on the
right-hand-side. For the RERTR-6 and -7A, the low Si-content plates consistently give
approximately three times thicker ILs than the 2% Si-content plates.
Fig. 2 Postirradiation metallographs of side-by-side test plates from RERTR-6, -7A, -9A
and -9B tests. The micrographs are from the hot side and the burnup is at the spot.
The ILs of Si-added plates are commonly uneven and the thicknesses are different among
neighboring particles. This is due to the local difference of the IL growth rate caused by the non-
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