A Monte Carlo investigation of the high power fundamental minority (D)T ICAF heating in JET is undertaken. The effects of the minority ion concentration, the location of the resonance layer, the symmetry of the wave field spectrum, the background ion temperature and the α-particle absorption of the ICRF power on the fusion yield are assessed in a projected reference discharge (ne(0) = 1020 m-3, Te(0) = 12 keV, Ti(0) = 10 keV, Prf = 25 MW, (PD + Pα)abs/Prf = 80%). Even with nD/ne approximately 30%, which is needed for high fusion yield, the finite orbit width and its related transport processes, such as the banana drift, and the RF induced diffusion and drift, are important and strongly reduce the attainable yield. However, as here the transferred power goes primarily to background ions, the increased target triton temperature can significantly improve the yield, and achieving Q( = Pfus/Prf) = 1 in JET would appear to be feasible. The use of the asymmetric wave field spectrum improves the confinement of the resonating ions and is shown to substantially enhance the yield and to extend the duration of its peak value. This effect, if also applied to tritons. could delay the characteristic deterioration of the peaked density profiles during the pellet enhanced performance modes, alpha -particle absorption of the RF power is found to be very small