VARIATION OF FISSION PRODUCTS
AND NATURAL RADIOACTIVITY IN SURFACE AIR
P, F, GUSTAFSON, S. 5S, BRAR, and S, E, MUNIAK
Division of Biological and Medical Research, Argonne National Laboratory,
Argonne, Illinois
ABSTRACT
Collection of particulates in surface air by air filters has been in progress at Argonne, I]l., for a number of years. Measurement of the radioactivity in these filters has been done by gamma-ray spectrometry
with the use of large Nal crystals. The concentrations of various fission and activation products as well as 'Be were determined by computer analysis of the complex spectra. Variations in the concentration
of various nuclides, particularly of !°7Cs and “Mn, as well as in the ratio
between nuclides, are used to determine the sources of debris observed
in surface air. The differences in distribution as a function of time are
discussed for various sources.
VARIATION OF RADIOACTIVITY IN SURFACE AIR
Airborne particulates were collected on asbestos-base filter paper
having an efficiency of approximately 96% for particles of greater than
0.25 in diameter exposed on air pumps operated at flow rates of approximately 40 m*/hr. Three such pumps have been in continuous op-
eration since mid-1961, providing daily samples from some 3000 m? of
air for these studies. Prior to this date portions of the filters from the
Industrial Hygiene and Safety Division onsite and offsite monitoring net-
work were used for analysis. Since September 1961, gross gammaactivity in the daily or two-day filter collections was determined by a
spectral method discussed in Ref. 1, which takes into account the con497