Hydrogen peroxide studies at elevated temperatures

The objectives of the work were to: measure the decomposition rates of hydrogen peroxide; determine the effects of various surfaces on the decomposition; add the data to the boiling water reactor (BWR) radiolysis model; and measure the electrochemical potential (ECP) of stainless steel under various conditions. Tests were carried out in the GE Vallecitos all-purpose test loop. The decomposition rate of hydrogen peroxide increased with temperature as expected. In Teflon tubing, the decomposition rates were much lower than that measured in either stainless or titanium tubing. The much higher rates in stainless steel decreased with increasing tubing diameter. Small amounts of hydrogen had no effects on the kinetics. Sulfuric acid increased the rates slightly compared to sodium chloride and sodium hydroxide, especially at lower temperatures. Copper salts at a copper concentration of 20 ppb increased the decomposition rates about 1 1/2 orders of magnitude over the whole temperature range. The effect of copper was measured only in Teflon tubing. There is a preliminary discussion of the decomposition mechanisms. The observed activation energy for the decomposition of hydrogen peroxide is about 16 kcal/mol. In a reactor the decomposition rates are much lower than in laboratory tests. Preliminary ECPs with respect to platinum or copper/copper oxide were reported for 304 and 316 stainless steels in solutions containing hydrogen peroxide or oxygen. The data showed that the potentials for stainless steel were shifted more positively with the addition of hydrogen peroxide than with dissolved oxygen at a similar level of total oxidant