Surface radioactivity resulting from the deposition of /sup 222/Rn daughter products
This paper describes the relationship between the /sup 222/Rn in air, and the level of surface radioactivity that results from the build-up and decay of the daughter isotope, /sup 210/Pb. Samples of /sup 222/Rn were collected from Mystery Cave, which is located in southeastern Minnesota and from the basement of a house in Minneapolis, MN. Lead-210 was measured on surfaces within the cave, on a rock removed from the cave, and on a basement window. Surface alpha activities were measured on the rock sample and on the window. Radon-222 concentrations in the cave air ranged from 3 to 13 kBq m-3. In the basement, /sup 222/Rn levels were between 0.2 and 0.4 kBq m-3. Virtually all the surface radioactivity resulted from the deposition and decay of airborne /sup 222/Rn daughter products and was not produced by the decay of U in the rock. Radon-222 concentrations in the cave air were almost 30 times higher than in the basement air; however, the surface /sup 210/Pb activity in the cave was 100 times higher than that in the basement. This suggests that in the cave air, /sup 222/Rn daughter products are more likely to reach the walls and decay to /sup 210/Pb. The measurements of surface alpha activity did not show a similar trend primarily because /sup 210/Pb had diffused further into the coating of dirt on the rock than into the glass of the window. The resulting surface activity of the rock was lower than expected based on the /sup 210/Pb concentration, because many of the alpha-emitting nuclei were at depths beyond the range of emitted alpha particles. On surfaces where the penetration range of alpha particles is greater than the diffusion depth of /sup 210/Pb atoms, either the /sup 210/Pb concentration or surface alpha-activity measurements should provide estimates of average long-term /sup 222/Rn concentrations.
- Research Organization:
- Minnesota Geological Survey, St. Paul
- OSTI ID:
- 6282142
- Journal Information:
- Health Phys.; (United States), Vol. 4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Natural radioelement solution by circulating ground waters in the Stripa granite
Preliminary study of the transport and distribution of radium, radon and their alpha-emitting daughters using nuclear emulsions and polonium-210. Final report
Related Subjects
BASEMENTS
RADIATION MONITORING
CAVES
LEAD 210
DEPOSITION
RADON 222
ALPHA PARTICLES
DAUGHTER PRODUCTS
GEOLOGY
INDOOR AIR POLLUTION
MINNESOTA
RADIOACTIVITY
SURFACE CONTAMINATION
AIR POLLUTION
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CAVITIES
CHARGED PARTICLES
CONTAMINATION
DAYS LIVING RADIOISOTOPES
EVEN-EVEN NUCLEI
FEDERAL REGION V
HEAVY NUCLEI
ISOTOPES
LEAD ISOTOPES
MONITORING
NORTH AMERICA
NUCLEI
POLLUTION
RADIOISOTOPES
RADON ISOTOPES
USA
YEARS LIVING RADIOISOTOPES
500300* - Environment
Atmospheric- Radioactive Materials Monitoring & Transport- (-1989)