RRFM 2009 Transactions - European Nuclear Society

Figure 6: Distribution of oxide thickness along the length of the coolant channel (Inlet at 0 cm
and outlet at 31 cm) for the test with pre-filmed plates.
4. Discussion and conclusions
The development of the oxide in heat transfer conditions can be approximately adjusted by
one of the published models [4] with values of experimental parameters similar to those
nominally used in the tests. The correlation between both experimental and theoretical
curves should be checked with tests of longer duration.
The strong pH effect observed in 120 hours tests could be related to the stability of formation
of aluminium oxides, which is known to be maximum at pH=5.07 [7]. A layer grown in that
particular condition may be more compact, thereby more protective.
The tested pre-oxidation treatment does not provide any corrosion protection in the
conditions of the experiments. Te pre-filming temperature was chosen above 70 ºC, which is
the known limit for the bayerite-bohemite transition; bohemite is said to provide a better
protection. It is possible that a higher formation temperature may be needed for the layer to
show this quality.
5. References
[1] J. C. Griess et al., "Effect of heat flux on the corrosion of Aluminium by water. Part IV",
ORNL-3541 (1964).
[2] R. S. Ondrejcin, "Evaluation of Mark 22 cladding", Savannah River Laboratory DPST-83-
324 (1983).
[3] S. J. Pawel et al., "Influence of coolant pH on corrosion of 6061 Aluminium under reactor
heat transfer conditions", report ORNL/TM-13083 (1995).
[4] Yeon Soo Kim et al, “Prediction Model for Oxide Thickness on Aluminium Alloy Cladding
During Irradiation.”, 25th Int. Meeting on RERTR, Chicago (Illinois), October 5-10 (2003).
[5] R. Haddad et al, “Study of Al Fuel Plate Oxidation”, Proceedings of RRFM 2008,
Hamburg March 2-5 2008.
[6] “Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water, IAEA-TRS-418
(2003).
[7] M. Pourbaix, Atlas of Electrochemical Equilibria in Aqueous Solutions, Pergamon Press,
Oxford (1976).
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