Some Transient Characteristics of PIUS

Transient characteristics of a process inherent ultimate safety (PIUS) reactor in typical accidental situations are investigated by using the plant dynamics analysis code THYDE-W. First, the modeling and steady-state adjustment for thermal hydraulics of a PIUS is described. Then the transient calculations are made for a pump coastdown, a steam generator feed-water trip, a flow blockage, and a boron dilution. They show that inherent safety of PIUS is ensured without control rod scram. The entrance of pool water to the primary loop, however, could give rise to a potential problem of thermal shock.