RRFM 2009 Transactions - European Nuclear Society

EFFECT OF Si ADDITION IN Al IN U-Mo/Al DISPERSION PLATES:
OBSERVATIONS FROM SIDE-BY-SIDE IRRADIATIONS
FROM RERTR-6, -7A, -9A AND -9B *
YEON SOO KIM, G.L. HOFMAN
Argonne National Laboratory
9700 S Cass Ave, Argonne, IL 60439 – USA
A.B. ROBINSON
Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-6188 – USA
ABSTRACT
The interaction layer (IL) thicknesses of four plate pairs with different Si content in the
matrix irradiated side-by-side from RERTR-6, -7A, -9A and -9B were compared. The
plate pairs from each test have the same fabrication and irradiation condition
(temperature, fission rate, burnup, etc). The pair from the RERTR-7A showed that a
pure-Al matrix plate (R0R010) had three times larger IL thickness on the hot side than
a 2% Si-added plate (R2R040). The Si addition also showed that pore formation was
effectively suppressed up to around full LEU burnup at typical RERTR test conditions.
However, the pair from RERTR-9B (8.5 gU/cm 3 ) with extremely high burnup (119%
LEU equiv.) showed that an initial stage of pore formation in plate regions with thick
ILs. The minimum as-fabrication Si content that needs to be added to provide the
beneficial effect is also assessed.
1. Introduction
The concept of adding Si in the Al matrix to reduce interaction layer (IL) growth and suppress the
formation of deleterious pores in the ILs has been tested extensively. The out-of-pile [1,2] and inpile
[3-5] tests showed generally consistent results with the theoretical predictions [6-8].
However, direct comparisons for the effect of Si addition using test plates with the same
irradiation conditions were not available.
In the RERTR program, the effect of Si has been in-pile tested extensively from the RERTR-6 to
the RERTR-9B. Some of the results from the RERTR-6 and RERTR-7A were reported
previously [3,4]. In the RERTR-7A, -9A and -9B, pairs of plates with different Si contents were
tested side-by-side. From these plates, we could examine more systematically the effect of Si
and the minimum Si content necessary to preserve its effectiveness on IL thickness reduction
and suppression of pore formation in ILs.
The plate pairs from the RERTR-7A have plate-average burnups of about 75% (LEU-equiv.) and
100% for those from the RERTR-9B. The maximum Si content tested in the RERTR program
was 5%. Because of the extremely high burnup for the RERTR-9, some plates showed evidence
that the as-fabrication Si content in the Al matrix was insufficient to sustain its effectiveness
throughout their lives.
* Work supported by US Department of Energy, Office of Global Threat Reduction, National Nuclear Security
Administration (NNSA), under Contract DE-AC-02-06CH11357. The submitted manuscript has been authored by a
contractor of the U. S. Government under contract NO.DE-AC-02-06CH11357. Accordingly, the U. S. government
retains a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others
to do so, for U.S. Government purposes.
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