A phantom for the evaluation of electrokinetic remediation of radioactive species from water saturated concrete is described. The phantom has been designed to be a general analogue for environments where structural concrete is saturated by radioactive aqueous solutions and where electrokinetic remediation may be deployed. It is also a specific analogue for the walls of storage ponds for legacy spend nuclear fuel pins where the pond water comprises a large volume of hazardous active waste that may penetrate the pond wall. The fabricated phantom was evaluated using a fixed electrical potential to monitor the rate of cationic transport of K+ through concrete samples of different thickness (20 and 35 mm respectively). Results of the evaluation show K+ diffusion coefficients of 5.20 × 10−13 and 7.61 × 10−13 m2 s−1 for the 20 mm and 35 mm samples, consistent with those seen in literature for the transport of caesium through concrete of similar thickness. The phantom offers a means of experimental validation of computational electrokinetic models as well as providing a basis to test the effects of electrode material on ionic transport rates, to interrogate the effects of pH on all components of the system, and as a basis for instruction, education and training in nuclear decommissioning and waste treatment.