Evaluation of a radon-in-water pilot-proficiency test

A pilot proficiency test (PT) on measurements of the massic activity of ²²²Rn in drinking water was organised by JRC-Geel. Fourteen environmental radioactivity monitoring laboratories were invited to participate. The key aim of the study was to test, optimise and stream-line the complete process for conducting such a PT in order to perform a large scale Europe-wide PT in a robust manner. The process involved using all state-of-the art knowledge on sampling, transporting and measuring ²²²Rn in water. It was found that the majority of the participants' results (92%) were within the ±15% reference range. The pilot-PT showed that the applied process was suitable and can be used for the large scale European PT planned for the third quarter of 2018.

[Radon transfer and intracorporal deposition of radon decay products under balneotherapeutic conditions]

The intracorporal deposition of radon decay products was determined on four persons after 40 and 30 min respectively in radon water with about 1500 Bq/L by wholebody gamma spectrometry. The measurements started about 2 1/2 h after exposure. In addition, the radon activity concentration of inspiratory and expiratory air was measured on one person during and after exposure and the deposition of radon decay products on the skin was measured on another person. The radon activity leaving the body with the expiratory air during exposure in the water (called "radon transfer") amounts to about 800 Bq. An intracorporal radon activity immediately after therapeutic exposure of about 3000 Bq was obtained as a result of first measurements by extrapolation from measurements starting about 2 1/2 hours later. Additional studies are necessary. There are indications that both the radon transfer and the intracorporal deposition can be increased by exposure in mixed radon-CO2 water.

Large-area low-level gross alpha ZnS scintillation counting

An efficiency of (44+/-2)% is achieved for samples placed directly on a 5 in diameter ZnS scintillator plate, placed on top of a 5 in photomultiplier in a light-tight pot. Background count rate is as low as (9+/-3)h(-1), equivalent to (5+/-2)mBq on 95 cm(2) for a second scintillator face to face or for a high-purity copper disk. Results are displayed continuously and printed on-line. An automatic repetition of measurements permits a measurement of activity as a function of time. From such a function radionuclides such as radon and its decay products may be distinguished from other radionuclides by their half-life in a technically simpler way than by their energy.

Fast retrospective determination of radon exposure with a sensitive alpha scintillation probe

The background of a hand-held alpha ZnS scintillation probe of 44 cm(2) was reduced from the normal 50 counts per hour (cph) to 4 +/- 2 cph and the efficiency increased to 34%. The limit of detection for a 30 min measurement is now 5 Bq m(-2) Po-210 on glass surfaces, corresponding to about 200 Bq m(-3) indoor Rn-222 exposure for 20 years. The probe was successfully used for retrospective determination of radon exposure. The probe is simpler, faster and more convenient, and more economic than alpha spectrometry or nuclear track detectors currently used in the field of lung cancer epidemiology and long term radon exposure.