HELENA: A HEAVY LIQUID METAL MULTI-PURPOSE LOOP FOR THERMAL-HYDRAULICS, CORROSION AND COMPONENT TEST

摘要

Since the Lead-cooled Fast Reactor (LFR) has been conceptualized in the frame of GEN IV International Forum (GIF), ENEA is strongly involved on the HLM technology development. Currently ENEA has implemented large competencies and capabilities in the field of HLM thermal-hydraulic, coolant technology, material for high temperature applications, corrosion and material protection. In this frame, the HELENA facility is well instrumented and it represents a loop working in pure lead for experiments in the field of corrosion for LFR structural materials, component test, and thermal-hydraulic investigations. The components and the process of the facility has been also depicted in some details. The scheduled working activities has been described and the main steps focused. A prototypical mechanical pump has been designed and manufactured to properly work in pure lead at high temperatures. The long-run test on the component will be isothermal at 400°C with low oxygen content ＜10~(-8) % in weight; the oxygen content will be monitored continuously. The pump will be gradually driven to the reference mass flow rate 35 kg/s and this mass flow rate will be maintained for 1500 h, i.e. 2 months about. After this, the pump is stopped and the loop is drained. Then, the pump impeller is disassembled by the body and it is analyzed for corrosion. Then, a test on the ball valves is carried out for a few months. At the end of 2014, the facility is upgraded with the insertion of the FPS in the heating section and with the secondary side. A 19-pin wire-spaced Fuel Pin bundle Simulator (FPS) is installed to measure clad temperature and heat transfer coefficients in different conditions in the different ranks of subchannels of the MYRRHA bundle. Therefore a test matrix on the forced convection condition in the wire-spaced bundle will be carried out. A 7 tube/shell-and-tube Heat Exchanger couples the primary lead loop with the secondary side with water in pressure at 100 bar. The tube-in-tube technology with lead tube side, water shell side, steel powder in the gap is adopted. Bubble tubes with flowing Argon are adopted to measure pressure losses in the different branches of the loop. Several thermocouples monitor the loop in different points. An ancillary gas system ensures the cover gas The paper reports the description of the experiments, the proposed test matrix and description the technological solution adopted for the HELENA implementation.