Airborne RadioactivityBy Beth Harmony

Reasons for the experiment:Radiation is something that we are constantly being

bombarded with from all directions. By taking a sample of the air, using a piece of filter paper, the amount of radiation that we breathe in can be estimated. The most common radiation that we are bombarded with is from radon 222, which comes up from the ground. Lead 214 is

a byproduct of the decay of radon 222, and is also heavy enough to get caught in the filter paper, making it a good candidate to look at.

How the experiment was done:A 62 cpm vacuum, with a piece of filter paper in it, was placed

in three different rooms, and ran for an hour and 20 minutes. The filter paper was then placed over a germanium detector, which detects

gamma radiation. The detector was run for 20 minutes, and then the peaks were analyzed. Each peak is associated with a specific energy,

and, in most cases, is unique to a single element. By looking at the peaks that are associated with lead 214, the amount of micro Ci/ml, the

amount of radiation in each milliliter, could be determined.

Source: Los Alamos Science

Uranium 238 Decay Series

Source: Cutnell and Johnson

Source: Los Alamos Science

Source: Los Alamos Science

Low Level Lab Sample 2-24-05 Live time 1191 seconds

Chalk Hill Sample taken 3-3-05 live time 1218 seconds

Keck Laboratory Sample taken 3-3-05 live time 1218 sec.

isotope Pb-214

gamma energy Raw Counts micro Ci/m(keV) under peak

Low Level Lab Sample 351.9 1090 6.646240E-11

Chalk Hill Sample351.9 570 3.475560E-11

Keck Lab Sample351.9 195 1.189010E-11

Detector Efficiency = 2.93%

Lead-214

AtomicNo. Radionuclide Class

Table 1Occupational Values

Table 2Effluent Concentrations

Table 3Releases toSewers

Col. 1 Col. 2 Col. 3 Col. 1 Col. 2

OralIngestionALI(µCi)

Inhalation

Air(µCi/ml)

Water(µCi/ml)

MonthlyAverageConcentration(µCi/ml)

ALI(µCi)

DAC(µCi/ml)

82 Lead-2142 D, all compounds 9E+3 8E+2 3E-7 1E-9 1E-4 1E-3

NRC Limits on Lead-214

Source: Radiological Health Handbook

Germanium Detector (red cover)Air filter paper (on lab book – darker circle)

Air sampling tool with clean white filter paper