US EPA

1432058 

Journal Article 

Radon (Thoron) Daughter Measurements with an Automated, Programmable, Radiation Monitor 

Bigu, J; Vandrish, G 

1986 

Yes 

Environmental Monitoring and Assessment
ISSN: 0167-6369
EISSN: 1573-2959 

NIOSH/00189888 

6 

1 

59-70 

English 

24254544 

10.1007/BF00394288 

A technical evaluation of an automatic programmable radiation monitor, the WL-1000C, was conducted under laboratory controlled conditions and in an uranium mine. The WL-1000C was an automated programmable grab sampler with alpha spectroscopy capabilities. It had three energy windows that could count alpha particles from radium-A and thorium-C in the first channel, radium-C in the second channel, and thorium-C in the third channel. Six methods for analyzing data were programmed into a self contained microprocessor. The alpha counting efficiency of the detectors and the sampling pump flow rate could be programed from the keyboard. The instrument was tested in a 26 cubic meter radon/thoron room of a radiation laboratory and in a uranium mine. The radon daughter containing atmospheres, radon daughter, and thoron daughter mixtures were monitored under constant or rapidly fluctuating radiation conditions. The radiation levels in the laboratory ranged from below 0.02 to 10 working levels (WL). Radiation levels in the mine ranged from 0.2 to 0.5WL. Radioactive aerosol concentrations in the radon/thoron room ranged from 1.0x10(3) to 2.0x10(3) per cubic centimeter (cc). Aerosol concentrations in the uranium mine were above 1.0x10(5)/cc. Parallel monitoring was performed with three conventional grab sampling methods and two automated radon daughter continuous monitoring systems, for comparison purposes. Good agreement was obtained between radon daughter WL data obtained by the WL-1000C and the other methods. When comparing the WLs for the radon/thoron daughter mixtures some discrepancies were noted. For example, the WLs obtained for radium-A by the WL-1000C were around 50 percent lower than those obtained by the grab sampling methods. The WLs for thorium obtained by the WL-1000C were usually higher than those obtained by the other techniques. The authors conclude that the major reason for the discrepancies is due to alpha/energy overlap between radium-A and thorium-C. 

DCN-186622; Analytical instruments; Radiation monitors; Radon daughters; Equipment design; Equipment reliability; Laboratory testing; Uranium mining; Alpha radiation