Radon and radon progeny in the Carlsbad Caverns
- Inhalation Toxicology Research Inst., Albuquerque, NM (United States)
- National Tsing Hua Univ., Hsinchu (Taiwan, Province of China)
- New Mexico Inst. of Mining and Technology, Socorro, NM (United States)
Measurements were made in July 1994 to determine air exchange rate, aerosol characteristics, radon concentrations, and radon progeny activity size distributions in the Carlsbad Caverns. The measured radon concentrations were stable at a level of 1821{+-}55 Bq m{sup -3}(mean {+-}SD). Using a SF{sub 6} trace gas method, it was determined that stagnant air in the Caverns was exchanged once every 18 days. The stagnant air was a key factor in maintaining stable environmental conditions and radon concentration. The low air exchange and few aerosol sources inside the Caverns also contributed to the low aerosol concentrations of between 200 and 400 cm{sup -3} - orders of magnitude lower than mining, indoor, and outdoor environments. The alpha spectrum showed radon progeny but no thoron progeny. The activity size distribution of radon progeny showed typical bimodal distributions with higher unattached fractions than other natural environments. The high unattached fraction was attributed to the extremely low aerosol concentration. Considering the seasonal variation in radon concentration, the estimated cumulative exposure of 1.65 working level months (WLMs) for a worker spending 2000 h in the Carlsbad Caverns with the observed radon concentration seems high, but it is still below the recommended occupational exposure limit for underground uranium miners. 43 refs., 11 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-76EV01013
- OSTI ID:
- 437743
- Journal Information:
- Aerosol Science and Technology, Journal Name: Aerosol Science and Technology Journal Issue: 1 Vol. 26; ISSN 0278-6826; ISSN ASTYDQ
- Country of Publication:
- United States
- Language:
- English
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