Based on the standard of the residual time distribution curve (RTD curve), the flow control devices in the slab tundish were optimized by numerical simulation method.

The quantitative token of the residual age index of DDT in soils was primarily discussed, and the normalized residual time index (NRTI) of DDT was designed as one of the methods.

This fallout material decays over a long period of time, and is the main source of residual nuclear radiation.