Integrating radon and WL meter

Two known measurement principles based on TL detectors were applied for design of RWLM-82 type instrument which enables simultaneous measurement of the average concentration of radon and of the working level over a few days. The instrument is a metal cylinder consisting of two parts. The upper one is a 3 liter compartment into which radon diffuses, and where 218Po originating from radon decay is collected electrostatically on the TL detector. The lower part contains an air pump sucking air trough a membrane filter where the radionuclides attached to aerosol particles are retained and undergo decay. The other TL detector facing the filter absorbs the part of alpha energy of the decayed nuclides. A third identical detector (0.1 mm teflon disc with 50% very fine CaSO4: Dy powder) serves as a gamma-ray background indicator. A 24-hr exposure at 30 Bq m-3 radon concentration and at 0.2 equilibrium factor is sufficient for obtaining a TL signal exceeding the detector background by a factor higher than 10. A special calibration chamber was constructed. It is equipped with a radon source ensured radon concentration in the chamber of 5 kBq m-3, an aerosol generator and appropriate measuring devices for monitoring the concentration of radon and its products. (author)