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.

Effects of Hydrogen Peroxide on Corrosion of Stainless Steel, (IV) Determination of Oxide Film Properties with Multilateral Surface Analyses

“…1,2) To determine the effects of H 2 O 2 , O 2 and their mixture on electrochemical corrosion potential (ECP) of type 304 stainless steel, the authors fabricated a high temperature, high-pressure water loop with a polytetrafluoroethylene (PTFE) inner liner which minimized H 2 O 2 decomposition and lowered possible oxygen concentration. [3][4][5][6][7] From in situ measurements, i.e., ECP and frequency dependent complex impedance (FDCI), made in previous papers, [7][8][9] the authors confirmed the following.…”

Water chemistry technology – one of the key technologies for safe and reliable nuclear power plant operation

“…However, in the optimal hydrogen concentration deter- [16] [18][19][20]. The models were extended to understand 16 N behaviors in the reactor water and main steam line [21].…”

Numerical Simulation on Effect of Methanol Addition on Coolant Radiolysis in Pressurized Water Reactor

“…8) In high-temperature water, hydrogen peroxide is thermally decomposed into oxygen and water. Therefore, oxygen concentration should be discussed based on effective oxygen concentration, [O 2 ] eff , 19) which is defined as In Tables 8-11, [O 2 ] eff is listed. Methanol concentrations of 1 and 4 ppm are sufficient to lower [O 2 ] eff below 10 ppb for -ray dose rates of 1 Gy s À1 and 10 kGy s À1 , respectively.…”