Research and Development on Hydrogen Production by Thermochemical Water-Splitting IS Process

A project using the High Temperature Engineering Test Reactor (HTTR) is being proceeded at the Japan Atomic Energy Agency (JAEA), which aims to develop technologies of nuclear production of hydrogen to meet its massive demand in future. The HTTR with thermal power of 30MW is the Japanese high-temperature gas-cooled reactor (HTGR), built and operated at the site of the Oarai Research & Development Center of JAEA. Under the HTTR project, JAEA has been conducting research and development on thermochemical IS process aiming to reach its final goal of demonstrating the nuclear hydrogen production by an HTTR-IS system. The IS process is a chemical process composed of three reactions, i.e. hydrogen iodide decomposition, sulfuric acid decomposition, and production of hydrogen iodide and sulfuric acid. JAEA completed one-week continuous hydrogen production using a glass-made bench-scale test apparatus equipped with an automatic control system in 2004, where the hydrogen production rate was about 30 NL/hr. Based on the successful test, present activity focuses on the development of components to be used in the corrosive process environments and, also, of technologies to realize high thermal efficiency of hydrogen production. This paper describes present status of the activities such as conceptual design of a test plant driven by sensible heat of helium gas heated by an electric heater simulating the HTTR, and component tests for service in the corrosive environments of high temperature sulfuric acid. Also, R&D results are described on glass lining technologies and a reliability evaluation of components made of SiC ceramics, which are promising candidates for application to, e.g. the sulfuric acid decomposer and the hydriodic acid distillation column.