A feasibility study is presented of fast tokamak plasma terminations by means of high-Z impurity liquid jet injections in order to reduce the technological requirements of such terminations. The calculation was carried out by combining models described for the jet ablation and the current termination and taking into account the ionization of the jet material exposed to generated runaway electrons. The liquid jet was assumed to fragment and thus to deposit more massive impurity ions in the plasma. Although argon or krypton jet injection generates the runaway electron current, it decays in several hundred milliseconds with ionization of the residual jet material. These high-Z impurity jet injections would also be applicable for terminating or reducing the runaway electron current tails generated by major plasma disruptions.