An improved sup 222 Rn canister using a two-stage charcoal system
- Department of Energy, New York, NY (USA)
A prototype for an improved passive {sup 222}Rn canister (R-Canister) was designed and compared to conventional charcoal canisters for its adsorptive and desorptive characteristics following exposures to {sup 222}Rn at 23{degrees}C in the presence of water vapor. The R-Canister, containing a two-stage charcoal system, minimizes the adverse effects of water vapor by maintaining the amount of adsorbed water vapor in the primary Rn adsorbent below the break-point of the charcoal. This is achieved by the placement of a desiccant charcoal cartridge 6 cm above the primary Rn adsorbent. The optimal bed depth of the primary adsorbent, determined from a diffusion study, was found to be 2.3 cm. The measured value for the effective diffusion coefficient of RN in a peat-based charcoal at 15% humidity and 25{degrees}C is 7.97 x 10(-10) m2 s-1. Exposures to 70% humidity for 7 d increased the buildup time-constant of Rn in the R-Canisters by 33% as compared to R-Canisters exposed to 15% humidity. At relative humidities ranging from 15-70%, the {sup 222}Rn buildup time-constant of the R-Canister ranged from 43-94 h, whereas the desorption time-constant ranged from 46-64 h. Typical buildup time-constants and desorption time-constants for conventional fully-opened charcoal canisters currently in field use ranged from 30-43 h and 17-29 h, respectively, over the same range of humidities.
- OSTI ID:
- 5897282
- Journal Information:
- Health Physics; (USA), Vol. 60:2; ISSN 0017-9078
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RADIATION MONITORS
DESIGN
RADON 222
RADIATION MONITORING
CHARCOAL
INDOOR AIR POLLUTION
RADIOECOLOGICAL CONCENTRATION
ADSORBENTS
AIR POLLUTION
ALPHA DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
ECOLOGICAL CONCENTRATION
EVEN-EVEN NUCLEI
HEAVY NUCLEI
ISOTOPES
MEASURING INSTRUMENTS
MONITORING
MONITORS
NUCLEI
POLLUTION
RADIOISOTOPES
RADON ISOTOPES
540130* - Environment
Atmospheric- Radioactive Materials Monitoring & Transport- (1990-)