The atmosphere-surface exchange of radionuclides at the Sellafield reprocessing plant

Abstract

A programme of field measurements has been undertaken in which the deposition rates of Pu and Cs have been measured around a nuclear reprocessing facility. Dry deposition velocities have been found to be typically in excess of 1 cm s −1 and were highest for Pu. On occasions, bulk deposition velocities for Pu averaged over a period of several weeks or longer were considerably in excess of 10 cm s −1. Such values can only be ascribed to the local resuspension and subsequent deposition of very large particles which have high deposition rates and which would not be efficiently collected by the air samplers used to determine the deposition velocities. Size fractionation measurements of radionuclides confirm a substantial presence of large particles. The overall study shows that the near-surface deposition flux is dominated by previous deposition rather than current atmospheric discharges.