A reconsideration of the external dose assessment for the Techa river population.

A new methodology is employed to infer the time course of the external dose rate that affected the Techa riverside population. This was accomplished using information on the radionuclide composition of released radioactive waste and from earlier and current data on the degree of the river floodplain contamination with (137)Cs. The new approach is proposed for use in the dose reconstruction. Compared to current assumptions it indicates a considerably higher dose contribution due to short-lived fission products from the predominant peak of contamination in 1951. Relative to the present Techa river dosimetry system (TRDS-2000) this information may increase the external dose estimates several fold and correspondingly reduce the solid cancer risk estimate.