Use of three new SSNTD methods for evaluating thorium contents in different building materials and measuring thoron and its progeny concentrations inside dwellings

Three new methods based on using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) were used for measuring thorium concentrations (in 10−6 g/g (ppm)) inside different building materials and evaluating the resulting concentrations of thoron and its progenies in dwellings built by the studied materials.The first technique consists of determining the probabilities for α-particles emitted by the uranium and thorium series inside the building materials or by the radon and thoron groups inside the dwelling atmosphere to reach and be registered as tracks on the SSNTD utilized and exploiting the resulting track density rates. The second method consists of evaluating the mean critical angles of etching of the CR-39 and LR-115 II SSNTD and measuring the resulting track densities registered on the detectors utilized. The third technique is based on calculating the detection efficiencies of the CR-39 and LR-115 II SSNTD for α-particles emitted by the uranium and thorium series in the building materials or by the radon and thoron groups in air and measuring track density rates registered on these detectors. The influence of the building material''s nature and ventilation rate on the thoron and its decay products inside the dwelling rooms studied has been investigated. [Copyright &y& Elsevier]