Radioiodine Release into the Atmosphere during Normal Operation of Nuclear Power Plants

Abstract

The specific emission rates of iodine isotopes into the atmosphere during normal operation of European and Russian NPPs with different types of reactor facilities were analyzed. The probability distributions for the specific parameters are asymmetric, and their median values tend to decrease. Three categories of NPPs were distinguished: those with the best, worst, and stable practice of the 131I emission. The current global atmospheric release of 129I from all the NPPs in the world is estimated at 0.8 kBq year−1. With an increase in the total installed NPP capacity to 632 GW, the global release of 129I from the NPP emissions will increase to 1.4 kBq year−1, which is two times lower than the rate of natural production of this nuclide from atmospheric Xe isotopes under the action of cosmic rays. Based on the measurements performed at separate Russian NPPs, the contribution of the aerosol and gaseous iodine forms to the total volume activity of the released iodine isotopes was determined. Under the conditions of normal NPP operation, gaseous iodine compounds make the prevalent contribution to the radioiodine emissions (65–85%).