This paper presents an eResearch tool for evaluating and comparing Chemical, Biological, Radiological and Nuclear (CBRN) source-backtracking algorithms. The tool enables users to define a CBRN threat scenario to be simulated, which includes the geographical area of concern specified through a map, the simulated threat sources and their placement, and the configuration of sensors. Users can define multiple searchers who act as clients that interact with a central server and search for the simulated radiological source or sources. Based on the simulated measurements received from the searchers, and a chosen source backtracking algorithm, the central server updates the source estimates and issues control vectors to guide each searcher.