We are developing in situ diffusion measurements in solids using short-lived radioactive ion beams provided from an isotope separator on-line (ISOL). We examined the feasibility of a new in situ nanoscale diffusion measurement method using a radioactive 8Li tracer by computer simulations. Under moderate experimental conditions, we have found that the detection limit of lithium diffusion coefficient can be improved to a low value of 1×10-12cm2/s. Also, in situ sodium diffusion measurement in Na battery materials can be applicable using a radioactive 20Na tracer. We found Na diffusion coefficients can be measured, ranging from 10-6 to 10-10cm2/s by computer simulations.© 2013 Elsevier B.V. All rights reserved.