Comprehensive modeling of hydrogen transport and accumulation in titanium and zirconium. (May 2020)

• Record Type: Journal Article
• Authors: Hamamoto, Yoshiki; Uchikoshi, Takeru; Tanabe, Katsuaki
• Is Part Of: Nuclear materials and energy. Volume 23(2020)
• Publication Date: 2020-05
• Subjects: Metal -- Hydride -- Kinetic model -- Adsorption -- Absorption -- Diffusion -- Desorption -- Hydrogen storage -- Nuclear reactor -- Fusion reactor; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2020.100751
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: The first hydrogen absorption model for Ti that accounts for the metal subsurface. The first hydrogen transport model for Zr for both absorption and desorption. Systematic analyses of the rate-determining steps on operational conditions. Maps of the effectiveness factors useful for designing practical nuclear equipment. Case studies for the fuel claddings to prevent hydrogen embrittlement. Abstract: We developed kinetic models of hydrogen absorption in Ti and Zr. The models comprise series connections of the hydrogen-transport processes of surface dissociative adsorption and recombinative desorption; subsurface transport; and bulk diffusion. Numerical calculations using the models quantitatively reproduce the results of experimental series of time-transient absorption curves at various temperatures, demonstrating the validity of our models. Experimental desorption curves at various temperatures are also reproduced by the same model equations and kinetic parameters, particularly for Zr, demonstrating the dual functionality of our single model for hydrogen-transport directions. We use an effectiveness factor defined as the ratio between the real absorption rate and the virtual rate neglecting bulk diffusion. The transitions of the rate-determining steps of hydrogen transport in Ti and Zr under various conditions – such as temperature, pressure, and metal object size and shape – are systematically analyzed. As a case study to test the applicability of our model, hydrogen accumulation in the fuel claddings of light-water nuclear reactors was simulated to determine the cladding thickness required to prevent hydrogen embrittlement during the practical operation period. Our versatile kinetic models could be a useful tool that can aid the structural design and optimization of nuclear materials and facilities.