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Radon Off-gassing From Military Artifacts

Kelly, David G.; Mumby, Timothy1

doi: 10.1097/HP.0000000000001099
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Military historical artifacts found in museum displays and storage locations were analyzed for their 226Ra and 222Rn progeny activities to determine the fraction of 222Rn lost to the environment. Gamma-ray spectroscopy using high-purity germanium detectors was used to determine 226Ra activity and infer 222Rn activity based on 214Pb and 214Bi. Analyses were conducted without affecting the structural integrity of the artifacts. 226Ra was measured directly after correction for solid angle and finite sample-detector distance. Although 222Rn can be similarly analyzed, the collection in charcoal of 222Rn off-gassed from the artifact after the establishment of secular equilibrium was preferable. 222Rn off-gassing rates vary greatly between the six devices studied, with a maximum off-gassing rate of 1,850 ± 50 Bq h−1. Large variations in off-gassing rate were also observed between an additional 30 nominally identical dials, with a mean and standard deviation of 7.7 ± 7.1 Bq h−1. The work is not predictive of airborne 222Rn activity within museums, where building size and ventilation are significant and unique to each location. However, the significant off-gassing rates and their large variation suggest that 222Rn activities may be elevated in enclosed locations, such as aircraft cockpits and storage facilities.

1Department of Chemistry and Chemical Engineering, Royal Military College of Canada.

The authors declare no conflicts of interest.

For correspondence contact David G. Kelly, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada, K7K 7B4, or email at david.kelly@rmc.ca.

(Manuscript accepted 12 March 2019)

Online date: June 18, 2019

© 2019 by the Health Physics Society