Effectiveness of massive gas injection (MGI) for mitigation of disruptive wall damage has been investigated. Cross-reference analysis of the available JET experiments on MGI and their simulations with the TOKES code allow concluding that in JET conditions one can convert into radiation the electron thermal energy and the plasma current energy, but the ion thermal energy does not converted into radiation because of very ineffective excitation of injected noble gas (NG) ions by D ions and long equipartition time between D ions and electrons. Rough extrapolation of the result on ITER conditions shows that one can expect irradiation of 90% of plasma total energy if current quench (CQ) duration in ITER is not shorter as in JET.