Operations using deuterium-tritium mixtures have been recently performed at JET during DTE2 (2021) and DTE3 (2023). These experiments will offer a unique possibility to study several open issues in support to ITER and DEMO, such as alpha particle heating, and to improve the plasma performance obtained in the previous DT campaign (DET1). During DT operation, each plasma discharge was a precious resource, being both T and neutron budget limited. It was thus mandatory to promptly detect and safely terminate those plasma discharges which did not achieve the expected target parameters. A real-time detector of underperforming discharges has been developed for this purpose and it is named the dud detector. The dud detector calculates and monitors the time evolution of plasma performance indicators, which can be used to trigger an alarm and a proper plasma termination. In this seminar, the experience gained on the algorithm’s behavior during DD and DT operations is presented.