Hydrazine and Hydrogen Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors, (I) Temperature Dependence of Hydrazine Reactions

Abstract

Hydrazine and hydrogen co-injection into reactor water is considered a new mitigation method of stress corrosion cracking in BWRs. Fundamental data such as the thermal decomposition of hydrazine, the reaction of hydrazine with oxygen and with hydrogen peroxide at temperatures ranging from 150 to 280 C are needed to evaluate suitability of this method. Reactions in bulk water were studied in a polytetrafluoroethylene pipe to separate surface reaction effects. The results were as follows. (1) The orders of the apparent reaction rate of hydrazine with oxygen were 1 and 0.5 for hydrazine and oxygen concentrations, respectively (À . Based on these data, the applicability of hydrazine and hydrogen co-injection into BWRs was considered. Hydrazine introduction to reactor water was confirmed to be accompanied by only 1% decomposition. The concentration of oxygen, which is injected to suppress the flow-assisted corrosion of carbon steel in current BWR operation, would decrease due to the reaction of hydrazine with oxygen. However oxygen concentration in feed water could be maintained at the required level if the concentration of oxygen injected in condensate water was at most doubled compared to the current operating concentration.

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

“…For this, precise [O 2 ] control in the secondary cooling system is required to mitigate any impact on SG tube corrosion, which was supported by results obtained with the N 2 H 4 -O 2 reaction model [67]. Reaction constants of N 2 H 4 and O 2 were from basic research study for N 2 H 4 and H 2 co-injection into BWRs [68].…”

Hydrazine and Hydrogen Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors (IV)

“…Therefore, we selected hydrazine and hydrogen co-injection (HHC), [7][8][9] which is done as hydrazine injection into reactor water with a small amount of hydrogen though the FW system, in order to mitigate a crack growth rate (CGR) by reducing bulk reactor water concentrations of oxidants. Required fundamental characteristics of the HHC are as follows:…”

The Effect Of Hydrazine Addition On The Formation Of Oxygen Molecule By Fast Neutron Radiolysis

“…While Ishida et al (2006) have developed a selected method to mitigate stress corrosion cracking in boiling water reactors (BWRs) named hydrazine and hydrogen co-injection (HHC) [7], which is injected through feed water system. Hypothetically speaking, hydrazine could suppress the oxygen formation as a major of corrosion initiator.…”