Ventilation rate values are calculated from track density measurements in solid state nuclear track detectors (SSNTD), both when ventilation is the main cause of radioactive disequilibrium in radon progeny, and when it shares importance with other agents. The method consists of exposing a SSNTD of high intrinsic efficiency (CR-39) in filtered and unfiltered conditions and, in addition, covered with a thin aluminum foil, to stop alpha particles from 218Po and 222Rn. No calibrations are required, but, when necessary, independent measurements of the loss rates of radioactivity to aerosol and to the walls have to be performed. Ventilation rates depend upon geometric detection efficiencies for alpha particles, obtained here by Monte Carlo simulation, taking into account the space distribution of emission positions. This may lead to sizeable corrections in ventilation and equilibrium factor values. Since geometric detection efficiencies depend upon alpha particle ranges in air, the influences of barometric variables are also discussed.
Thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) studies were carried out on samples of 237Np4+ doped CaSO4/SrCO4. TSL glow peaks with Tmax around 395 and 425 K in CaSO4, and 425 K in SrSO4, were observed on samples gamma-irradiated at 300 K. The prominent TSL around 425 K in CaSO4/SrSO4 was found to coincide with the temperature at which the EPR signals of SO4− radical ions diasappear. The trap depth value for this process has been determined from both TSL and EPR data. A comparison is made of the trap depth values obtained for “hole” detrapping at the sulphate site in various actinide doped CaSO4/SrSO4 lattices studied in our laboratory. The average activation energy was found to be in the range 0.8–0.9 eV.
