Similarity Analysis of the VISTA Thermal-Hydraulic Integral Test Loop for a Small-Break LOCA of the SMART Design

A thermal-hydraulic integral effect test facility, VISTA ITL, for SMART design is being constructed by the Korea Atomic Energy Research Institute (KAERI). The VISTA ITL is a modified version of an existing VISTA facility to have the simulation capability of small break loss of coolant accident (SBLOCA) by installing steam pressurizer, safety injection system, steam generator bypass, pump discharge line, downcomer, PRHRS makeup tank, break simulator and break measuring system, etc. The VISTA ITL is a 1/2.77-height, 1/1310-volume scaled test facility based on the design features of SMART. The reference scale ratios of length (1/2.77) and area (1/472.9) are based on the elevation difference between core and steam generator centers and the core flow area, respectively. According to the scaling law, the reduced height scaling results in time-reducing results in the model as the time scale ratio is 1/1.664. The reference plant of the VISTA ITL is a 330-MW (thermal) class integral type reactor, SMART, which is being developed by the KAERI. The SMART reactor is characterized by the introduction of simplified and improved safety systems such as passive residual heat removal system (PRHRS) and its integral arrangement of the reactor vessel assembly. In this study, a pre-test analysis of a SBLOCA is performed to understand the general behavior of the VISTA ITL and to assess the similarity between the VISTA ITL and the SMART design. The analysis is performed by using a best-estimate system analysis code, MARS-KS which was developed by KAERI, with the same control logics, transient scenarios and nodalization scheme for both systems of VISTA ITL and SMART design. The analysis result can provide a good insight into unique design features of the VISTA ITL and the thermal-hydraulic characteristics of the SMART design