Non-linear MHD simulation results of pellet injection show that MHD forces can accelerate large pellets injected on the high field side of a tokamak to the plasma centre. Magnetic reconnection can produce a reverse shear q profile. Ballooning instability caused by pellets is also reduced by high field side injection. Studies are also reported of the current quench phase of disruptions, which can cause 3-D halo currents and runaway electrons.