ACTION LEVELS FOR RADON EXPOSURES CAUSED BY RADON EXHALATION FROM RELICS OF URANIUM MINING AND MILLING

摘要

Because the effect of the outdoor radon from mining relics occurs in houses, the logical conclusion is to treat it - from the radiological point of view - in the same manner as the indoor radon exposure caused by other geogenic or technogenic sources. For indoor radon the German Commission on Radiological Protection has defined a 'normal range' of concentration up to 250 Bq/m~3 [5] derived from the measured frequency distribution in German houses. Below this level, no remedial measures are considered necessary. From the same basic idea, i.e. orientation to the natural range of variation, the outdoor radon must be radiologically evaluated by setting the upper end of the regional natural range as a reference level, thus separating the 'no action' from the 'action' range. But a general problem remains with respect to outdoor radon emitted from mining relics: there is somebody responsible for this particular radon source and for the resulting exposure, and consequently for remedial measures at the source, if required. That makes it necessary to define a source related contribution to the outdoor concentration at the sites of houses which is acceptable from the radiological point of view and above which remedial measures must be considered. Taking into account all the aspects described, the following conclusions can be drawn with respect to radon exhaled from mining relics in the mining regions of Saxony and Thuringia: