Development of 3-pin fuel test loop MARS model

Fuel Test Loop(FTL) has been developed to meet the increasing demand on fuel irradiation and burn up test required the development of new fuels in Korea. It is designed to provide the test conditions of high pressure and temperature like the commercial PWR and CANDU power plants. And also the FTL have the cooling capability to sufficiently remove the thermal power of the in-pile test section for normal operation, Anticipated Operational Occurrences(AOOs), and Design Basis Accidents(DBAs). This report deals with the development of the 3-pin fuel test loop MARS model. The MARS model has been developed to predict the thermal-hydraulic transient behavior of the FTL on the AOOs and DBAs. The Main Cooling Water(MCW) system including the in-pile test section(IPS) and the Emergency Cooling Water(ECW) system are included in the model. The other systems connected to the MCW system are not included in the model. The test fuel is modeled as a heat structure component having 7 axial nodes and 11 radial meshes. The control systems of the pressure, temperature and flow rate for the MCW system are simplified and the protection systems of HANARO and the fuel test loop are implemented in the model. It is indicated that the steady state conditions of pressure, temperature, and flow rate for the thermal hydraulic transient analyses of the facility are obtained adequately by the FTL MARS model