The early SMART concept adopted an in-vessel pressurizer type with an inherent self-pressure regulating capability designed to operate via the thermo-pneumatic balance between the water, steam and nitrogen gas which are the three fluids that fill the pressurizer. In the event of a rupture of a pipe line connected to the pressurizer at a high system pressure, a mixture of water, steam and nitrogen is discharged through the break at critical flow conditions. The computer codes for the safety analysis of SMART need to use a verified and validated model for this critical flow. To investigate the thermal-hydraulic phenomena of the critical flow affected by the non-condensable gas entrained in the two-phase break flow, a separate effects test facility was designed and installed at the KAERI site. The test facility can be operated at a temperature of 323 °C and pressure of 12 MPa, with a maximum break size of 20 mm in diameter. A nitrogen gas flow-rate of up to 0.5 kg/s can be injected and mixed with a two-phase mixture in the test section to simulate the transient behavior expected during a LOCA. The test data from the facility were used for the development and verification of the critical break flow model for SMART.

Integral effect test

The SMART-P is a pilot plant of the integral type reactor SMART which has new innovative design features, aimed at achieving a highly enhanced safety and improved economics. An experimental verification by an integral simulation for a transient and accident (VISTA) facility has been constructed to simulate the various transient and events of an integral reactor. The VISTA facility (Figure 15.2) has been used to understand the thermal-hydraulic behavior including several operational transients and design basis accidents. During the past five years, several integral effect tests have been carried out and reported, including performance tests, reactor coolant pump (RCP) transients, power transients and heat-up or cool-down procedures, and safety-related design basis accidents. It contributes to verifying the system design of the reference plant.