The flow rate measurements of dual-phase pipe flow were conducted with a couple of sealed radioisotopes for the cross-correlation technology. The flow was produced in an acrylic tubing of which internal diameter is 8cm and into which pressurized nitrogen gas was periodically injected. Under the given conditions where the distance between two sources is four times of the diameter, N/S ratio ranges from 0.12 to 0.15 and the data sampling time is 4ms, the measured flow rates were estimated with the maximum relative error of 1.7%. From the subsequent experiments, it was proven that the closer the distance between the two sealed sources is, the higher the precision of measurement result is. It is anticipated that the industrial application of the technique for flow rate measurements in an in-service process can play an important role for monitoring multi-phase process media in petrochemical and refinery industries.