The present report is a study of loss of coolant accidents transients in ITER. A whole bunch of analyses has been done with AINA 3.0, the safety code developed by Fusion Energy Engineering Laboratory (FEEL-UPC) on the basis of SAFALY. First a short introduction to the world of fusion energy is made. Next, a description of the ITER project and the characteristics of the reactor are done. A description of a LOCA event and an Overview of AINA code are following. Finally, the explanation and the analysis of the simulation results is explained. Several LOCA events are investigated: • LOCA accident with a size of 33% on every blanket module for 400MW, 500MW and 700MW fusion power operation of the reactor. • LOCA accident with different sizes on the most and the less affected module of the blanket for 500 MW fusion power operation of the reactor. • Scanning of different Delay Time multiplayer and initial beryllium fraction for a LOCA accident with a size of 33% on every blanket module for 500 MW fusion power operation of the reactor. A comparison between the results obtained with AINA 3.0 and the past versions of the code (AINA 1.0 and the previous AINA 3.0) is also performed with the objective of demonstrate the validity and the improvement of the code.