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3.4.2 Dose rate

External dose can be assessed by using passive devices, which integrate the gamma radiation over the measurement period, such as thermoluminescence dosimeters (TLDs), the film badge and track etch. A device that possesses both active and passive qualities is the electronic dosimeter.

A typical TLD can detect radiation level approximately at 0.005 uGy/h but, at least one month exposure time is necessary. If all infrastructures for performing TLD measurements exist, it is an inexpensive methodology since the detector itself is of low cost (and re-useable). Its disadvantage is the long period of exposure required and special care is needed so as not to lose the TLD during the exposure time in an unguarded area. Film badges have similar properties but are more sensitive to the environment in which they are deployed (temperature, humidity) and require greater care and a larger facility for preparation and analysis.