Investigating Hydrogen Generation and Corrosion in the Treatment Tank and the Potential Formation of a Floating Layer in Neutralization Tank During Waste Tank Heel Chemical Cleaning

Treatment Tank Corrosion Studies for the Enhanced Chemical Cleaning Process

“…Similar shifts have been observed in PUREX wastes as well [1,18]. However, the shifts were observed after longer exposure times, perhaps indicating that a different chemistry with slower kinetics.…”

“…After bulk waste removal, the ECC process can be used to dissolve and remove much of the remaining sludge heel from Type I and II HLW tanks. The ECC process is similar to the previous chemical cleaning technology [1] in that oxalic acid is used for both, but the ECC process differs from the previous technology in the following ways: 1) The sludge heel will be washed with water rather than supernate; 2) dilute oxalic acid (i.e., 1 or 2 wt%) is used in place of concentrated oxalic acid (8 wt%); and 3) most of the resultant oxalate is decomposed by an Advanced Oxidation Process (AOP). Reducing the amount of oxalic acid used for dissolution of sludge and the subsequent oxidative destruction of oxalic acid will lead to a reduction of downstream impacts.…”

“…Observations from the results of the polarization scans suggest that the corrosion rates are very similar. OCP measurements in PUREX/8 wt.% oxalic acid stimulant were made previously [1] at temperatures of 50 °C and 75 °C. The OCP shift was clearly observed in these tests as well and the final OCP was in the range of -0.1 to 0.2 V vs. Ag/AgCl, similar to the results for sludge simulants in the 1 wt.% and 2.5 wt.% oxalic acid.…”

“…August 2011 Revision 1 100 of 112 The results from the present coupon tests were compared with the results of coupon tests conducted with Tank 5F sludge (PUREX) simulant in 8 wt.% oxalic acid [1]. These Tank 5F tests were conducted at a temperature of 50 and 75°C and the solutions were not agitated.…”

Alternative and Enhanced Chemical Cleaning: Basic Studies Results Fy2010

“…The corrosion rate for carbon steel in 0.75 M sulfuric acid at 45 °C is approximately 0.8 inches year (Craig, 1989). One of the reasons for selecting oxalic acid for chemical cleaning is that carbon steel corrodes at a relatively low general corrosion rate of approximately 0.06 inches per year (Herman, 2007). For a short contact time between the oxalic acid and the steel tank, on the order of two months, this corrosion rate results in a loss of approximately 0.01 inches from the tank wall.…”