Effect of Heat Flux on the Corrosion of Aluminum by Water. Part Iii. Final Report on Tests Relative to the High-Flux Isotope Reactor

Abstract

The effect of very high heat fluxes on the corrosion of 1100 and 6061 aluminum alloys by water was investigated. The purpose of the investigation was to determine whether aluminum would have adequate corrosion resistance for use as a fuel-element cladding material in the High-Flux Isotope Reactor; therefore the test conditions generally simulated those expected to exist during reactor operation. At heat fluxes between 1 and 2 x lo6 E3tu/hr*ft2 and with coolant temperatures and velocities in the ranges of 131 to 250°F and jl to 51 fps, respectively, a layer of boehmite (~A~~o~. H~o)

Oxidation of aluminum alloy cladding for research and test reactor fuel

“…Postirradiation micrographs [1,5,8,[11][12][13] revealed that thin oxide films were free of cracks or pores, which suggested that the thermal conductivity degradation of thin oxides is negligible. As the oxide film thickened further, however, its thermal conductivity decreased due to porosity increase (or crack development).…”

“…As the oxide film thickened further, however, its thermal conductivity decreased due to porosity increase (or crack development). After reviewing the data [1][2][3][4][5][8][9][10][11][12][13]18], the threshold thickness was tentatively set at 25 lm. The decrease was assessed by an empirical function of the oxide thickness at a rate giving k T = 1.85 W/m-K at x = 50 lm, which was deduced from the data reported by Griess [1].…”

“…The reaction temperature governing the Al oxidation reaction in steam is known to be the metal-oxide interface temperature [1,17]. In this situation, the oxidant transport through the oxide is the reaction controlling process.…”

“…There are oxide thickness prediction models based on out-ofpile data [1][2][3][4][5]. All of them are power law models and were developed for data from out-of-pile loop tests.…”

“…An empirical model [6] consisting of correlations predicting the oxide film thickness on aluminum alloy cladding for both out-ofpile and in-pile tests was developed several years ago as a function of test time, oxide-water interface temperature, heat flux at cladding surface, coolant water pH, and coolant flow rate for the relevant coolant channel using the measured data from out-of-pile [1][2][3][4][5]7] and from in-pile tests available in the literature [8][9][10][11][12]. After this empirical model was developed, oxide thickness measurements became available from the RERTR (reduced enrichment for research and test reactors) tests in the advanced test reactor (ATR).…”