Empirical Understanding of the Dependency of Hydrogen Water Chemistry Effectiveness on BWR Designs

Abstract

Dependency of hydrogen water chemistry (H\VC) effectiveness on plant specifications and operational conditions has been studied for an empirical interpretation. The H\VC effectiveness was calculated exactly by employing a water radiolysis model requiring results of complex fiow analysis and dose distribution analysis as input, in addition to the plant specifications. It was found that decrease of oxygen concentration in the reactor water in the reactor recirculation system could be taken as an exponential function of H2 concentration added to the reactor water. Thus, the recombination factor p which was the coefficient of hydrogen concentration in the exponent could represent the recombination efficiency in the downcomer region. The p corresponded to the apparent reaction rate constant of the recombination reaction of H202 with H2, which included radical concentrations produced by irradiation, multiplied by the residence time in the downcomer. The dose rate index 'f of each plant was introduced as a measure of downcomer dose rate. Since the recombination efficiency was known to depend on the downcomer dose rate, functional dependence of p on ')' was found to be linear. The HWC effectiveness at the reactor pressure vessel bottom region could also be evaluated using p.

Formation of H2O2 in TiO2 Photocatalysis of Oxygenated and Deoxygenated Aqueous Systems: A Probe for Photocatalytically Produced Hydroxyl Radicals

“…18−21 The main reason for this is the importance of such processes in nuclear technological installations. 22 These studies have shown that hydrogen peroxide undergoes catalytic decomposition, primarily to form adsorbed hydroxyl radicals, on oxide surfaces of the type M x O y . 23 The overall process is described by reactions 4 and 5.…”

“…The reactivity of hydrogen peroxide toward metal oxide surfaces has received increasing attention during the past decade. − The main reason for this is the importance of such processes in nuclear technological installations . These studies have shown that hydrogen peroxide undergoes catalytic decomposition, primarily to form adsorbed hydroxyl radicals, on oxide surfaces of the type M x O y .…”

Effects of Hydrogen Peroxide on Corrosion of Stainless Steel, (II) Evaluation of Oxide Film Properties by Complex Impedance Measurement

“…Oxygen and hydrogen peroxide concentrations change along the recirculation flow path so that the corrosive conditions differ between locations in BWR primary cooling systems. 1) Several indexes for corrosive conditions have been proposed to evaluate the effects of hydrogen water chemistry (HWC) in BWR plants. [2][3][4][5] One of the most common indexes of corrosive conditions is electrochemical corrosion potential (ECP).…”

Evaluation of Effectiveness of Hydrogen Water Chemistry for Different Types of Boiling Water Reactors.

“…According to a previous study< 14 ) ( 15 ), the contribution of [H 2 0 2 ] to the [0 2 ]eff in the reactor water is often larger than [0 2 ] and the apparent recombination reaction of [H202] with [H2] is expressed as…”

“…The previous study< 15 ) has shown that the recombination factor can be expressed as a function of the average dose rate at the downcomer region, which can be obtained as a result of the radiation transport calculation. An approach to obtain an approximate value (designated as the dose rate factor, g) for the average dose rate at the downcomer region, I'd, is expressed as follows: In Table 4, major plant parameters are compared between Tsuruga-1 (BWR-2) and Tokai-2 (BWR-5).…”