Thermal Hydraulic Characteristics of the Integral Type Reactor: SMART-P for Variation in Heat Removal Capability

The SMART is an integral type reactor with new innovative design features aimed at achieving a highly enhanced safety and improved economics. This paper focuses on the thermal hydraulic experimental program for the development of SMART. Thermal hydraulic responses for the transient operations of the SMART-P are experimentally investigated by using an integral effect test facility. The test facility (VISTA) has been constructed to simulate the SMART-P, which is a pilot plant of the SMART. The VISTA facility is a full height and 1/96 volume scaled test facility with respect to the SMART-P with a power of 65 MWt. In the present study, the VISTA facility was subjected to various transient conditions in order to understand the thermal-hydraulic responses following transients and finally to verify the system design of the SMART-P. Several experiments, including a heatup, a main coolant pump (MCP) speed change, and a power change, have been performed to investigate the heat transfer characteristics and the natural circulation performance of the primary system and the Passive Residual Heat Removal System (PRHRS) of the SMART-P by using the VISTA facility. Performance tests of a passive residual heat removal system (PRHRS) have also been carried out for its design optimization. Besides, several design basis accidents, such as an increase or a decrease of the feedwater flow, a loss of coolant flow, a control rod withdrawal, and a limited case of a loss of coolant accident (LOCA) on the line to the gas cylinder are under investigation in order to understand the thermal-hydraulic responses and finally to verify the system design of the SMART-P. Especially, the details of the experimental results for a loss of feedwater accident and a power increase accident due to a control rod withdrawal are explored in the present study. (authors)