Engineering Scale Test on Sodium Leak and Fire Accident and Its Consequences in Auxiliary Building of Fast Breeder Reactors

Himeno, Yoshiaki; not registered  ; Morii, Tadashi*; not registered

Using sodium from 180kg to 3 metric tons, a series of tests has been conducted to develop the fire mitigation system and to study a design basis sodium leak accident and its consequences in the auxiliary building of the fast breeder reactor. In the test, flow pattern of a realistic leak from the sodium piping was investigated at first. Combustions of sodium in an open pool and a pool with a reduced opening were also studied together with combustion and flow of a sodium on an inclined steel liner and in a drain piping. Transient thermal conduction of a steel lined floor concrete during a sodium leak was tested and evaluated. In next, based on the results obtained, a fire mitigation system was developed and was mounted in a two storied concrete test rig. Then, a large scale test starting from a leak and ending by a self-extinguishment of a fire in the smothering tank was carried out. In final, consequences of sodium aerosols deposition on the reactor components and the electrical instruments have been experimentally studied.