Abstract
The accident at Fukushima Daiichi nuclear power plant happened on March 11, 2011 revealed that the long station blackout causes a possibility of breakout of nuclear reactors. This accident may occur not only by tsunami or earthquake but also long term absence of operators. The author has proposed a cooling system that can continue cooling the nuclear reactor without external electric power supply or the support of operators. This system is composed of natural convection cooling tower and heat exchangers. Power required to operate the system is supplied by the decay heat of nuclear fuels. This paper describes the performances of natural convection cooling heat exchanger and feasibility of the system.
