Simple relations are given, which could help to estimate the expected annual savings resulting from the application of radioisotope methods for the mixing time, segregation effect or residence time distribution determination. Criteria for estimation of benefit at optimum transition of the continuous production from one quality to another, criteria for estimate the benefits on basis of known holdup and for estimate of benefits resulting from knowledge of the distribution function of residence time and of the kinetics of chemical reaction are presented. Further are demonstrated two examples of evaluation of the economic effect of the results of a system analysis in chemical industry where beside the measurements od residence time distribution by help of radiotracers are used also results of other experimental methods and that practically without increasing production cost.