Experimental campaign on pressure wave propagation in LLE

Experimental facility THALLIUM was designed and installed at ENEA C.R. Brasimone to reproduce the geometry of the LLE (Lithium Lead Eutectic) loop of HCLL TBM. Within the framework of F4E-FPA-372, an experimental campaign was carried out in ITER relevant conditions. The experiments simulated a pipe rupture in a cooling plate of the HCLL TBM, injecting He from an injection valve connected to He-FUS3 loop. The aim was to study the release of high pressure He in LLE due to In- box LOCA. The fundamental phenomena to be observed are the pressure wave trend in the two pipes reproducing the pipe forest of the HCLL-TBM in ITER and the effectiveness of the mitigation strategy designed for HCLL-TBS. The main parameters that were varied during the experiments are: injection time, actuation of the isolation valves and opening pressure of the rupture disc. In the pipe forest mock-up, the pressure wave showed three distinct peaks, related to the water hammer, to the LLE oscillations in the expansion tank and to He which fills the loop. The isolation valves proved to have a deep influence on the pressure wave propagation also when they do not close, being able to damp the first pressure peaks.