NUKLEONIKA 2010, 55(4):529-533



Milko J. Križman1, Jože Rojc2, Josef E. Peter3

1 Slovenian Nuclear Safety Administration, 16 Železna Str., SI-1000 Ljubljana, Slovenia
2 Žirovski Vrh U-Mine, 1 Todraž Str., SI-4224 Gorenja vas, Slovenia
3 Federal Office for Radiation Protection,
Ingolstädter Landstrasse 1, D-85764 Oberschleissheim, Germany

The term “radon event” indicates here a sudden appearance of enhanced radon concentrations, observed like well expressed peaks in time series of radon concentrations. The peaks are superimposed on normal diurnal periodical curves. The characteristics of radon events are high peak values, a rather short duration and a low radon equilibrium factor. Since radon events appear only in the environment near significant radon emission sources, they were investigated in more detail in the case of the former Žirovski Vrh uranium mine (Slovenia), using the existing network of continuous radon progeny measuring devices. Eight different types of radon events were identified in the vicinity of the U-mine disposal sites, lasting for some hours and with the range of their peak levels of equilibrium equivalent concentrations (EEC) of radon from a few Bq·m–3 to over 200 Bq·m–3. Exposures to radon events in units of Bq·h·m–3 were estimated for adult individuals of the reference group. They resulted in relatively high effective doses of the range 1–5 µSv per a single event, thus exceeding, e.g. the total effective dose for the public due to radioactive discharges from most nuclear facilities during the whole year.

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