CHAPTER 3-PROCESS HEAT HTR APPLICATIONS

A.E.BOHÉ; H.E.P.NASSINI

Advances in Nuclear Power Process Heat Applications

International Atomic Energy Agency (IAEA)

Lugar: Viena Austria; Año: 2009;

Hydrogen can be produced by thermo-chemical and/or electrochemical processes using nuclear energy as the primary thermal energy source. Nuclear energy can be used in hydrogen production mainly in three ways: By using the electricity from the nuclear plant for conventional liquid water electrolysis (electricity + H2O [liquid] ¡æ H2 + O2). By using both the high-temperature heat and electricity from the nuclear plant for the high-temperature steam electrolysis (electricity + H2O [steam] ¡æ H2 + O2) or the hybrid processes (electricity + heat + H2O ¡æ [cyclic chemical reactions] ¡æ H2 + O2). By using the heat from the nuclear plant for thermo-chemical processes (heat + H2O ¡æ [cyclic chemical reactions] ¡æ H2 + O2). Even the conventional liquid water electrolysis is a commercially proven technology that can be driven by the present generation of low-temperature water-cooled nuclear power reactors, it may not present an energy-efficient hydrogen production method for the long term since higher process temperatures are required for more efficient thermo-chemical and electrochemical hydrogen production reactions. Consequently, nuclear technologies capable of producing reactor coolant temperatures on the order of 700¨¬C or higher are expected to be suitable for large-scale hydrogen production in the future. Since they can reach the required high temperatures, gas-cooled reactors, molten-salt-cooled reactors, and heavy-metal-cooled reactors, appear to be the most promising technologies to be coupled to the hydrogen plants for efficient production [1-3]. High-temperature operation of both the nuclear plant and the hydrogen plant imposes stringent heat transfer-associated design requirements that demand materials development as well as intricate design requirements for integrated plant layouts, which consequently affect the cost of each technology. Furthermore, the safety of the three components of the complex should be carefully analyzed: the hydrogen plant, the nuclear reactor and the coupling of the two. In the following, the main processes under development for hydrogen production using HTRs as a primary energy source, are analyzed: