I've got some experience of searching for a turbine disc which has gone walkabout. Olympus 301, No2 on Vulcan XM604, approx 1,200 feet over Rutland fields in January 68. The flight path of the aircraft was known precisely.
Dozens of us searched for days. Nothing was ever found. I also lived in Singapore for 14 years and know that a Rutland Field is as concrete compared to the soil on Batam Island.
I'll be amazed if more shrapnel is ever found.