HE-FUS3 Experimental Campaign far the Assessment of Thermal-Hydraulic Codes: Pre-Test Analysis and Test Specifications.

This report deals with the design of an experimental campaign to be conducted in the HE-FUS3 loop (CR BRASIMONE) in order to provide an experimental data base for the assessment of thermal-hydraulic codes used for HTR and VHTR design and safety analysis. In order to support the definition of the test matrix a pre-test activity has been carried out with the T/H system code RELAP5. To this aim a RELAP5 model of the loop (the related input deck is provided in attachment A of this report) has been developed taking advantage of the results ol previous assessment activities and already available experimental data. The pre-test activity has allowed defining a set of transients representative of operational and accident conditions that are of particular meaning for the assessment of T/H codes: the plant start-up by steps, 2 Loss of Flow Accidents with a different dynamic of the accidental event, 2 Loss of Coolant Accidents at different loop pressure. On the basis of the calculation results reported in the chapter 4 it has been possible to draw up the test specifications in attachment B taking into account the requirement for the operation of the HE-FUS3 loop and the actual conditions of the instrumentation implemented in the facility.