Direct measurement of multi-noncondensable and steam mixture under an accident condition of a Passive Containment Cooling System (PCCS)

The Passive Containment Cooling System (PCCS) has a function to remove the long-term decay heat following an accident by condensation. As an extension of the PCCS development program, its heat removal capability under a severe accident condition has been tested. The effect of the lighter noncondensable than steam on the PCCS heat transfer characteristics was clarified. Helium gas was used to simulate hydrogen gas which can be generated by metal-water reaction. In the final stage, multi-noncondensables (i.e. both nitrogen and helium) were simultaneously confined. The GIRAFFE measurement system was accordingly modified so that noncondensable gas concentration was directly measured. Due to installation of direct measurement system of noncondensable, the noncondensable transport mechanism was modeled so that the analytical code might be remarkably improved. (author)