Libro de resúmenes [revisión final, 172 páginas] - UGM

Geos, Vol. 27, No. 1, Octubre, 2007GEOLOGÍA Y GEOFÍSICA AMBIENTALPyramid radon levels were lower than in Sun Pyramid due to itshigher ventilation rate. Therefore the Equivalent Effective Dose(HE) calculated for the highest concentration, taking into accountthe conversion factors proposed by ICPR 65, was around 1 mSvy-1 (2000 h, work year and an equilibrium factor F=0.4). On theassumption that workers spent one fourth of the year (500 hy-1), HE= 0.279 mSv. All values are much lower than the actionlevel 3-10 mSv y-1. Thoron concentration was around 400 Bqm-3 similar to those found in China for cave dwellings. Gammaexposure rates measured by the thermoluminiscent dosimeters ofCaSO4: Dy + TFE were in the Sun and Moon pyramids of 2.59± 0.42 µR h-1 and 7.02 ± 0.07 µR h-1. Doses derived from themare very low. As a part of the Quality Assurance Program, theprecision in the field for different detection systems was evaluatedby the relative mean deviation of several sets of duplicate samplesand it was lower than 13%.73