The efficiency of ICRH in TFR was limited in the 1981 experiments by an important influx ofmetallic impurities in the plasma core. Using carbon limiters and different materials for theantennas Faraday shield leads to a significant decrease of the metallic impurity content : incontrast with the previous results, the increase of temperature associated with the RF pulseremains now constant for more than 0.1 s. However, the power radiated by the metallic ions atthe end of the RF pulse still reaches an appreciable fraction of the total RF power,particularly when using an antenna generating the RF wave from the low magnetic field side ofthe plasma. This effect is attributed to an interaction of the RF wave with the low densityplasma located in the scrape off layer.