A passive radon dosemeter suitable for workplaces

The results obtained in different international intercomparisons on passive radon monitors have been analysed with the aim of identifying a suitable radon monitoring device for workplaces. From this analysis, the passive radon device, first developed for personal dosimetry in mines by the National Radiation Protection Board, UK (NRPB), has shown the most suitable set of characteristics. This radon monitor consists of a diffusion chamber, made of conductive plastic with less than 2 cm height, containing a CR-39 film (Columbia Resin 1939), as track detector. Radon detectors in workplaces may be exposed only during the working hours, thus requiring the storage of the detectors in low-radon zones when not exposed. This paper describes how this problem can be solved. Since track detectors are also efficient neutron dosemeters, care should be taken when radon monitors are used in workplaces, where they may he exposed to neutrons, such as on high altitude mountains, in the surroundings of high energy X ray facilities (where neutrons are produced by (gamma, n) reactions) or around high energy particle accelerators. To this end, the response of these passive radon monitors to high energy neutron fields has been investigated.