Rate Constant For The H˙ + H2O → ˙OH + H2 Reaction At Elevated ...

Rate constant for the H˙ + H2O → ˙OH + H2 reaction at elevated temperatures measured by pulse radiolysis

Y. Muroya, a S. Yamashita,b P. Lertnaisat,†c S. Sanguanmith,d J. Meesungnoen,d J.-P. Jay-Gerin d and Y. Katsumura ‡*bc Author affiliations

* Corresponding authors

a Department of Beam Materials Science, The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

b Nuclear Professional School, School of Engineering, The University of Tokyo, Shirakata-shirane 2-22, Tokai-mura, Naka-gun, Ibaraki, Japan E-mail: [email protected]

c Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, Japan

d Département de Médecine Nucléaire et de Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada

Abstract

Maintaining the structural integrity of materials in nuclear power plants is an essential issue associated with safe operation. Hydrogen (H2) addition or injection to coolants is a powerful technique that has been widely applied such that the reducing conditions in the coolant water avoid corrosion and stress corrosion cracking (SCC). Because the radiation-induced reaction of ˙OH + H2 → H˙ + H2O plays a crucial role in these systems, the rate constant has been measured at operation temperatures of the reactors (285–300 °C) by pulse radiolysis, generating sufficient data for analysis. The reverse reaction H˙ + H2O → ˙OH + H2 is negligibly slow at ambient temperature; however, it accelerates considerably quickly at elevated temperatures. Although the reverse reaction reduces the effectiveness of H2 addition, reliable rate constants have not yet been measured. In this study, the rate constants have been determined in a temperature range of 250–350 °C by pulse radiolysis in an aqueous I− solution.

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