In the framework of the OECD/NEA/CSNI/WGAMA group, a new activity on the "Status report on thermal-hydraulic passive systems design and safety assessment" has been started. University of Pisa is the Lead Organization. Within this regard a benchmark exercise, based on the experimental data developed in the Full Scale PERSEO (in-Pool Energy Removal System for Emergency Operation) component separate effect test facility, which was in operation at SIET, has been proposed and approved by the "WGAMA task group on TH passive system". An "OPEN" benchmark exercise is planned and it is hosted by ENEA. PERSEO is a full scale facility aimed at studying a new passive decay heat removal system operating in natural circulation. It was built at SIET laboratories in Piacenza (Italy) modifying the existing PANTHERS IC-PCC facility. The facility was conceived as an evolution of a previous CEA-ENEA proposal (thermal valve device) which moved the SBWR-IC primary side drain line valve to the low pressure pool side. Therefore, the main innovation in PERSEO facility is the presence of two pools connected by a line with a triggering valve. In this way it is possible to fill the pool, where the heat exchanger is located, only when needed for safety reasons. Among the four actual tests performed in the PERSEO experimental campaign, test number 7 has been chosen for its completeness. In fact it is a full pressure test (7 MPa) that investigates both the system stability and the long term cooling capability (system operation) of the system itself. The test is divided into two parts, both described in this report. Finally, the Fast Fourier Transform Based Method that will be used to evaluate quantitatively the accuracy of the simulation performed with system codes is described.