Study on enhancement of heat transfer in the reactor vessel auxiliary cooling system of a fast breeder reactor

The reactor vessel auxiliary cooling system (RVACS) is one of the decay heat removal systems for the fast breeder reactor. This system is so simple that it can attain high reliability and plant cost reduction. However, the heat removal capacity of this system is small compared to that of an immersed type of decay heat exchanger, because the heat transfer coefficient at the outside of the reactor vessel is not large. The object of this study is to propose a new method which is able to use thermal radiation effectively. The tests reveal that the heat transfer coefficient, using high-porosity porous bodies as a heat collector, surpasses that with no collector, especially at the upper end. (author)