[en] Transient testing of MYRRHA type fuel started at the TRIGA-ACPR Reactor. MYRRHA is a lead-bismuth cooled fast reactor under development by SCK-CEN. The goal of our project is to develop new testing methodologies and experimental devices for transient tests on Liquid Metal Fast Reactor type fuel, aimed to establish the fuel failure threshold (expressed in energy deposition) for cladding failure due to the Pellet Cladding Mechanical Interaction (PCMI). Based on the reactor physics assessment and the test fuel segment design, the design, fabrication and licensing of a new irradiation rig has been completed. Twenty uranium dioxide test fuel segments have been manufactured at SCK-CEN to be used in the tests. The un-irradiated test segments have been designed such that they resemble, as much as possible, a MYRRHA fuel pin at high burnup level. This is achieved by reducing the pellet-cladding gap size and a modification of the cladding cold-worked fraction. Fuel performance simulations have been carried out to evaluate expected values of energy deposition producing fuel failure. The paper presents a synthesis of the computational and experimental effort carried out, as well preliminary results and conclusions based on the first pulse experiments performed at the TRIGA-ACPR reactor. (authors)