Round robin exercise of the candidate ATF cladding materials within the IAEA ACTOF project

The paper presents a summary of the round robin test activity organized within the IAEA ACTOF project. The test conditions and sample matrix were finalized during fall 2017 and the tests have been performed during the next 14 months. Two fundamental experimental tests related to normal operating conditions and accidental conditions of LWRs were defined: High-temperature steam oxidation and Long-term corrosion tests. Originally, four laboratories/institutes joined the round robin exercise - CTU in Prague, KIT, VTT, and INCT. Later, also MTA EK joined the activity. Zircaloy-2 substrate was provided by Westinghouse Electric Company and two institutes applied their protective coatings on its surface (CTU - pure Cr coating and INCT - ZrSi-Cr coating). KIT applied MAX phase coating on Zircaloy-4 substrate. Additionally, AISI 348 steel provided by USP, Brazil was tested. The geometry of the samples varied based on the needs of particular institutes. Long-term corrosion tests were performed by three laboratories in PWR and VVER chemistry for at least 63 cumulative days. High-temperature steam oxidation tests were performed by four institutes at three pre-defined conditions. Participants performed pre- and post-characterization of the material based on their standard procedures and available techniques. The paper summarizes motivation, plans, sample matrix, materials, testing conditions and preliminary results including lessons learnt. Full reports will be published in the ACTOF TECDOC under preparation.