Can We Pre-locate Shiel/Screen Defects in MV Cables Using TDR?

If your shield wires are grounded at some point or multiple points along its path, then grounding the far end and testing with a TDR will not yield the results you wish. The TDR will show only the paths to the nearest available grounded points. If the first corruption encountered is substantial enough, then you will only see that.

If you want to use a floating (secondary) ground with the test equipment and connect that to the far end you may have a chance at your goal. You have to control your return path through isolation.

I think I got lost when you switched from conductor, to shield, to screen.

If you know that the cable has a corrupted shield along its path, then I think you know the general health of the cable...it sucks.

TDR will tell you if/where there is a sudden change in impedance somewhere along the cable's length. If the impedance changes suddenly along the way, some fraction of the pulse's energy will be reflected back to the source. Knowing the propagation velocity will tell you where. The polarity of the reflection will tell you in which direction the impedance changed. Go back to your basic transmission-line theory and look at the problem from that angle. If the line is terminated in its characteristic impedance and there are no discontinuities, there will be no reflection, because the terminal impedance looks like just more transmission line. Think about your TDR set and how it works, and of your cable as a classic transmission line. Introduce various flaws in your model, one at a time, and analyse the results from a theoretical perspective. Therein lies your answer. Not only, but you'll be way ahead of everyone else who are content to merely follow a procedure.