engleski

The occupational exposure during characterisation, conditioning and securing of radioactive sealed sources in Croatia – case study

In order to compare passive personal dosimeters to an active electronic one, a study of occupational exposure during decommissioning of an old temporary storage of radioactive sealed sources was conducted (the Storage project). All the workers involved in decommission (supervisors and those who actually worked with sources) were under specific (additional to regular surveillance) dosimetric surveillance using film dosimeters, TLD and active electronic personal dosimeters ALARA OD simultaneously. Gammaspectrometric measurements were carried out prior and upon the decommission, covering the area in front of the storage, where overall waste from the storage was inspected for any misplaced sources. Radon concentration measurements were conducted inside the storage after decommission. The whole work was finished in 10 working days. Total occupational doses received by individual workers during characterization, conditioning and securing of radioactive sealed sources were in range from 0 to 20 mSv in ten days. Results for accumulated dose and dose rates obtained by ALARA OD provided a new insight into an occupational exposure of workers due to the fact that ALARA OD AEPD (Active Electronic Personal Dosimeter) records the time when the fractioned external exposure occurred and the duration in seconds of the given exposure. That is important when dose was received within short-time interval during the characterization of the source, when the radiation source suffered technical failures or when the handling difficulties occurred while moving the source from its original sealed container to a new waste container. Occupational dose upgraded with the dose rate data obtained with active electronic dosimeters allows the specification of real occupational burden to workers and reconstruction of their occupational exposure (mode of operation – work regime) in time.

AEPD; sealed sources; occupational dosimetry; radiation protection; waste management

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