Experimental Study for Conceptual Validation of SMART PCCS

There are several types of passive safety system equipped in the SMART, passive residual heat removal systems (PRHRS), passive safety injection system (PSIS) with automatic depressurization system (ADS), and passive containment cooling system (PCCS). The PCCS is essential to reduce not only the temperature and pressure of containment building, but also radioactive substance after accident. The previous design concept of PCCS in the version of SMART standard design approval (SDA) was using an external heat exchanger with atmosphere air and a spray on the top of containment to reduce the temperature and pressure, and radioactive substance. The condensed steam increases temperature and level of water in the IRWST. When the cooling capacity of IRWST reduced, emergency cool-down tank (ECT) of PRHRS is used as alternative heat sink in the system. It is important to define the cooling capacity of IRWST because it determines an operating time of PCCS. Although the effect of radioactive substance dissolving in the IRWST cannot be evaluated due to the problems concerned with regulation and safety, but the cooling capacity of IRWST should be validated. The objective of this study is a thermal-hydraulic validation of the newly suggested PCCS design concept with a scaled down test facility. The SISTA, SMART IRWST separated test apparatus, is a separated effect test facility to validate the new PCCS design concept during anticipated accidents. The design values of PCCS in the SMART were produced with MARS calculation by FNC. The SISTA was constructed according to the scaled down design values. The dry well and IRWST of SISTA were designed with scaled down volumes following the Ishii"s scaling method.