Passive Measurements of Thoron and its Progenyin some Dwellings in Ireland

摘要

In this paper , an account is given of the development ,calibration and field use of a passivealpha track detector sensitive to thoron as well as to radon. No database of thoron and thoron progenyconcentrations in dwellings in Ireland exists and, as a result, the level of exposure of the Irishpopulation to thoron and its progeny is unknown. As an initial or pilot stage in establishing such a database measurements of thoron and thoron progeny concentrations (the latter expressed in EquilibriumEquivalent Thoron Concentration (EETC)) were made in 40 randomly chosen Irish dwellings. TheEETC measurements were made using a passive thoron progeny deposition rate monitor designed andsupplied by NIRS (Japan). In addition standard unmodified SSI passive radon detectors were used tomeasure radon in these dwellings. The measured thoron concentrations ranged from below the levelof detection to 154 Bq/m~3while the radon gas ranged from 15 to 179 Bq/m~3. The thoron progenyEETC values for these dwellings ranged from 0.03 to 7.7 Bq/m~3An account is also given of thedosimetric implications of these measurements.