Merit Assessment of Nuclear Hydrogen Steelmaking with Very High Temperature Reactor

摘要

The merit assessment of the nuclear hydrogen steelmaking (NHS) was performed for reduction of CO_2 emissions from the steelmaking process which accounts for approximately 14% of the total emissions in Japan. The NHS process is composed of the steelmaking process by hydrogen reduction and hydrogen production process using nuclear energy. As for nuclear hydrogen production, the combination of a very high temperature reactor (VHTR) and the thermochemical water splitting method, namely IS process, can be said to be the optimal, considering economics, safety & reliability, nuclear proliferation resistance and so on. Especially, VHTR has the excellent safety features outstanding as compared with the other nuclear reactors that the reactor can be shut down inherently and cooled down passively using natural heat radiation from outside of the reactor pressure vessel even in a loss of coolant flow accident caused by loss of power and so on. Therefore, hydrogen can be supplied directly to a shaft furnace using piping from VHTR installed near the steelmaking plant. The NHS process with VHTR and IS process can decrease the CO_2 emissions by approximately 9% of those of the conventional blast furnace process, and be economically competitive to the blast furnace and the shaft furnace processes.