Evaluation of radiation safety for ionization chamber smoke detectors containing Am-241

Abstract

The safety assessment was carried out for ionization chamber smoke detectors (ICSDs) containing 241Am under normal use and accident scenarios. The internal and external doses were estimated using dose coefficients and associated calculations. In normal use of the ICSDs with the activity in a range of 0.002-1 MBq per ICSD, the external doses to an individual for installation, use and maintenance were found to lie in the range of (0.01-4.17)×10-3 (0.017-6.76)×10-1 and (0.006-2.5)×10-2 μSv/y respectively. The activity of 241Am for domestic smoke detectors contains approximately 40 kBq per ICSD. The corresponding committed effective doses to a fire fighter during a fire and for cleanup operation after a fire via inhalation were found to be 6.1×10-5 and 0.024 μSv/y respectively. The committed effective dose equivalent to an infant via ingestion would be 148 μSv/y. The doses arising from normal use and incidents of ICSDs are less than 10 μSv/y and 1 mSv/y respectively which do not exceed the dose criteria for exemption from regulatory control. It could be concluded that the resultant radiological risk are estimated to be very low and lower than 1 mSv which is the annual dose limit to a member of the public for the safe use.