Absent a check valve in the pump discharge, the reservoir into which the pump is discharging will drive the pump backwards, the pump will drive the turbine backwards, and if liquid is introduced to the turbine again, the shock load of sudden reversal will break something. ... if the first reversal didn't.
... That is but one possible scenario that could be constructed around the insufficiently specified problem you have provided. A different set of assumptions than those I inserted could result in an entirely different outcome.
I.e., there may be an infinity of possible event sequences that intersect the sort of fuzzy data point you have provided. If you are only concerned with event sequences that are possible with specific turbines and specific pumps and specific fluids, none of which you have identified either, there may be only half an infinity of possible intersecting event sequences, depending on an infinity of design details of the specific devices that you have not specified, and the design details of specific devices interfaced thereto, that you have also not specified.
IOW, if we had some ham, we could have ham and eggs, if we had some eggs.
Mike Halloran
Pembroke Pines, FL, USA