CR-39 and LR-115 plastic detectors were used in air volume of several sealed cylinderical plastic tubes (can-technique) for time integrated long term measurement of radon activity concentrations. Dried soil samples, collected from the Egyptian Nile delta, were used. The tubes, 3.8 cm inner diameter and 20–170 cm in heights, were filled at the bottom with the dry soil samples up to different thicknesses (10–160 cm). The registeration sensitivities of CR-39 and LR-115 nuclear plastic detectors in the sealed tube, taking into consideration the plated-out activity on the walls, are discussed. The porosity of the soil samples, the diffusion length, the effective and real radium-226 contents were estimated. The results showed that the sealed tube technique could be used as a useful tool for the measurement of the radium concentration with reasonable accuracy.