HELIOS (Heavy Eutectic liquid metal Loop for the Integral test of Operability and Safety of PEACER) has been developed at NUTRECK (NUclear TRansmutation Energy research Center of Korea) in order to test the operability and safety of the liquid Pb-Bi cooled PEACER.
Main objectives of HELIOS are to verify the natural circulation feasibility and long-term operability of liquid LBE coolant in the PEACER system. The main design criterion for HELIOS was to obtain the maximum possible similarity of natural circulation capability between HELIOS and PEACER-300. Importance of the natural circulation ability continually increases in advanced nuclear energy systems because it assures passive safety features. In order to obtain the similarity, HELIOS was designed to have the same height and the same total pressure loss coefficient as the PEACER-300. The height of the HELIOS loop is 12-m and the thermal center difference is 7.4 m. HELIOS consists of the primary side with LBE and the secondary side with a single phase oil. The main components of HELIOS are a core, an expansion tank, a heat exchanger, a mechanical pump, an orifice, a gate valve, a tee junction, a 45¡£ elbow, a 90¡£ elbow, and straight pipes with 49.5 mm inner diameter. Four electric heating rods in the core are the principle heat source, yielding 60 kW maximum power. The heat exchanger on the top of HELIOS acts as a heat sink. The LBE flows downward in the shell side of the heat exchanger while the secondary fluid flows through upward on the tube side. The function of the expansion tank is to accommodate the level change and to control the oxygen activity in LBE. The centrifugal sump type mechanical pump with about 14 m of LBE head and 14 kg/s of flow rate was adopted in HELIOS.
With high expectation about HELIOS data, a multi-national systematic study on LBEwas proposed in 2007,which covers benchmarking of thermal hydraulic prediction models for Lead-Alloy Cooled Advanced Nuclear Energy System(LACANES). This international collaboration has been organized by OECD/NEA, and nine organizations – ENEA, RSE, GIDROPRESS, IAEA, IPPE, KIT/IKET, KIT/INR,NUTRECK, and RRC KI – contribute their efforts to LACANES benchmarking.